Planar flow casting melt-delivery arrangement for producing metallic foils

Abstract

A planar flow casting melt-delivery arrangement (220, 220A) configured for the production of metallic foils from a metallic material, the melt-delivery arrangement (220, 220A) comprising a high temperature receptacle (124, 124A) that includes: at least one chamber (240, 240A, 242, 242A) configured to hold a metallic melt therein; a nozzle (222, 222A) having at least one nozzle aperture (227, 227A) configured for the egress of the metallic melt from the at least one chamber (240, 240A, 242, 242A) for foil formation; and at least one filter (246, 246A, 246B) located within the at least one chamber (240, 240A, 242, 242A), each filter (246, 246A, 246B) configured to remove impurities from the metallic melt flowing therethrough.

Description

PLANAR FLOW CASTING MELT-DELIVERY ARRANGEMENT FOR PRODUCING METALLIC FOILSTECHNICAL FIELD

[0001] This disclosure broadly relates to a new melt-delivery arrangement configured for planar flow casting production of metallic foils, a planar flow casting system incorporating the melt-delivery arrangement, an associated planar flow casting method of forming metallic foils, and resultant metallic foils including shape memory alloy foils. The melt-delivery arrangement and associated planar flow casting method and system is particularly applicable for producing foils formed from precision thin metal and alloys, amorphous metals and alloys, or shape memory alloys, for example foils formed from non-ferrous metals and alloys. However, it is to be appreciated that this disclosure should not be limited to that application and may be used to produce other types of foils and / or thin metallic products using planar flow casting.BACKGROUND

[0002] The following discussion of the background is intended to facilitate an understanding of the invention. However, it should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was published, known or part of the common general knowledge as at the priority date of the application.

[0003] Precision Thin Metals are a group of thin (for example 0.01 to 1.5 mm) and ultra-thin (for example 0.00175 to 0.015 mm) amorphous and crystalline metals and alloys including (but not limited to) electrical steel, stainless steel (Fe) and nonferrous metals / alloys made from or alloyed with titanium (Ti), nickel (Ni), zirconium (Zr), vanadium (V), cobalt (Co), copper (Cu), aluminium (Al), neodymium (Nd) or the like. These types of metals enable end-users to design lighter, smaller and more efficient high-value products in a wide range of industrial applications, such as aerospace, defence, medical devices, renewable energy, and industrial processes. As a result of the complexity and variety of working conditions in these applications, precision thin alloys are required to have both a thin gauge and a precision of properties. The latter is predominantly dependenton the accuracy of the alloy chemistry and the precision control of fabrication conditions.

[0004] Shape memory alloys (SMAs) are smart materials that can recover their original shape under thermal stimulus such up being heated to a higher temperature - past the transformation temperature. One example of a SMA is Nickel-Titanium (Ni-Ti), which can also be characterised as a precision thin metal. The transformation temperature of SMA alloys can decrease about 100 °C from +50 °C to -50 °C if the alloy composition increases by 1 atomic (at) % from 50 to 51 at% as can be seen when studying the alloy composition versus transformation temperature. The accuracy of the alloy chemistry is therefore important for the proper functioning of these alloys.

[0005] The preservation of alloy composition of precision thin metals and shape memory alloys is therefore important, particularly when the alloys are molten. This requires a manufacturing process in which contamination or other compositional altering processes such as oxidation are minimised, and preferably prevented, during processing. However, manufacturing precision thin alloys and shape memory alloys into foils can be difficult using existing ingot casting and rolling routes due to poor formability of these metals and alloys at room temperature and a tendency to become contaminated at high temperatures. Traditionally these characteristics have limited their fabrication route to repetitive cold rolling with extensive intermediate vacuum annealing between rolling passes. However, the numerous rolling passes and vacuum anneals are extreme energy intensive and the repetitive vacuuming treatment at high temperature can also change the alloy composition by depleting alloying elements from the based alloys. Such traditional fabrication routes therefore have a high production cost to provide contamination-free and chemistry-precision alloys foils. For example, a typical supplier in Europe or US usually charges more than $17000 per kg or more for Grade 1 and Grade 2 Ti-containing or based foils of less than 0.1 mm thickness (circa August 2023). Consequently, existing fabrication technology are mainly used to manufacture thicker and lower grade foils and sheets, for example foils having a 0.2 mm or larger thickness.

[0006] Alternate fabrication techniques are thus desired. One fabrication technology under development is planar flow casting, which solidifies metallic melt into solid foils directly. Here, metallic melt flows through a wide and narrow slit held in close proximity to a casting or chilling wheel such that a metallic melt liquid puddle is able to bridge the narrow gap spacing between the nozzle and the wheel. Rapid solidification process occurs that quenches metallic melt into solid foils at a cooling rate in a range of 103to 107K / s. A solidified ribbon leaves the liquid puddle region. Planar flow casting therefore eliminates intermediate processing steps such rolling steps, pointing towards a low-cost and large volume manufacturing process for precision thin alloy foils.

[0007] However, whilst there have been many attempts to fabricate precision thin alloy foils, difficulties have prevented a wide adoption of the technology for the foil production. When fabricating shape memory alloy foils using planar flow casting methods, only narrow (less than 2 to 8 mm) width and short-length foils (shorter than 300 mm length) have been produced using conventional planar flow casting techniques. The limited foil dimension has been thought to be the result of various foil quality and processing failures that are originated by the presence of chemistry impurities, including brittleness, pinholes in foils, partially formed foils, blocked melt-delivery nozzles and the like.

[0008] When planar flow casting amorphous alloy foils, the precision control of the process, instead of the chemistry, is a key difficulty. Amorphous steels, such as based on Fe-B based alloys, can be advantageous over the traditional crystalline silicon steels in increasing energy efficiency of electrical distribution transformers and electric motors, as a result of their advanced magnetic permeability and low core loss properties. The transition from crystalline to amorphous microstructures can only be enabled at high cooling rate up to 107K / s, which is equivalent to planar flow casting (PFC) at very high speed e.g. up to 30 to 50 meter / second, reducing foil thickness to 25 to 30 pm or less.

[0009] It would therefore be desirable to provide an improved planar flow manufacturing technique capable of producing foils, for example foils formed using precision thin metals and alloys.SUMMARY

[0010] It has been found that one challenge in planar flow casting of precision thin metals foils and shape memory alloys arise from the fact that these metals alloys are highly reactive with oxygen either in air or from oxides present in surrounding materials when the metal is molten at high temperature. The resultant oxide films and / or inclusions in the molten metal often block the nozzle opening, impeding and / or preventing foil formation, and even fracturing the nozzle if these impurities become jammed between the casting or chilling wheel and the bottom of the nozzle. It has been identified that oxygen contamination may also be responsible the presence of a number of foil defects, for example pinhole defects, and poor foil ductility.

[0011] Another challenge in planar flow casting of precision thin metals foils and shape memory alloys arise from fluctuations in cooling rate due to a lack of precision control of the metallic melt flows travelling from the melting-holder crucible directly toward a narrow nozzle aperture. In the fast-paced operation of planar flow casting, the precision control of the metallic flows by measuring the metallic melt head in a crucible in a traditional nozzle is extremely challenging if not impossible. Consequently, this lack of precision control of the metallic melt flow may lead to a fluctuation in cooling rate when the molten metal is in contact after existing the nozzle. This fluctuation introduces an instability in solidification, which has much stronger detrimental effects on the quality of thin foils (e.g. 20 to 30 pm thickness) than of thicker foils (e.g. 40um or greater thickness). These amplified effects result in inconsistency in thickness, microstructures and properties of thin metal foils produced, including the amorphous steel thin foils of 20 to 30 pm or less.

[0012] This new development assists in addressing at least some of the above challenges with planar flow casting of metallic foils, particularly planar flow casting of large-width foils formed from precision thin metals and alloys foils, e.g. amorphous steels and shape memory alloys.

[0013] A first aspect provides a planar flow casting melt-delivery arrangement configured for the production of metallic foils from a metallic material. The melt-delivery arrangement may comprise a high temperature receptacle, which may include at least one chamber configured to hold a metallic melt therein. The receptacle may comprise a nozzle having at least one nozzle aperture configured for the egress of the metallic melt from the at least one chamber for foil formation.

[0014] The arrangement (e.g., at least one chamber) may be configured to remove impurities from the metallic melt, before feeding to the nozzle. In similar words, the arrangement may be configured to retain impurities (e.g., originating from or associated with the metallic melt) within the at least one chamber, before feeding to the nozzle. In some examples, the arrangement may comprise at least one filter located within the at least one chamber. The at least one filter may be configured to remove impurities from the metallic melt flowing therethrough (e.g., and retain those impurities at the filter).

[0015] This first aspect provides a new melt-delivery arrangement for the scalable precision-production of metallic foils by planar flow casting. In some examples, the arrangement may include at least one filter that acts as an impurity filter for metallic melt flowing therethrough.

[0016] When metallic melt flow through the filter, selected impurities are removed as a filtride from the metallic melt, whilst the filtered metallic melt forms the filtrate that passes through the filter. This provides a specified melt treatment (i.e., filtering impurities) in the planar flow casting (PFC) process enabling the meltdelivery arrangement to remove impurities from the metallic melt prior to being cast as a foil.

[0017] This functionality can assist in the fabrication of quality metallic foils, in particular from precision thin metal and alloys and / or shape memory alloys, such as stainless steel, high-melting-temperature nonferrous alloys like titanium (Ti) based or containing alloys, or crystalline or amorphous metals or alloys (for example crystalline and amorphous steels, crystalline and amorphous, Zr, Mg, Ti, Cu, or the like based or containing alloys).

[0018] Advantageously, this new melt-delivery arrangement can assist in (1) producing large-width (e.g., 200 to 300 mm for amorphous steel foils, >30 mm fornon-ferrous alloys such as Ti-Ni) metallic foils by planar flow casting that are defect-free and (2) producing thin foils of less than 40 um thickness (e.g. 20-30 um thick amorphous steel foils) with improved control of foils thickness and consistence of properties.. It should be understood that by defect-free, the foil does not have defects such as pin holes, oxide inclusions and / or other impurities, or similar defects. These types of defects can for example be included in the foil from the metallic melt when the foil is formed.

[0019] It should be appreciated that what may be considered to be a large-width metallic foil is dependent on the composition of that metallic foil. For example, for stainless steel foils a width of 200 to 300 mm may be considered to be a large- width foil produced by planar flow casting. For nonferrous alloys like titanium (Ti) based or containing alloys (e.g. Ti-Ni alloys) a width of >30 mm may be considered to be a large-width foil.

[0020] It should be appreciated that impurities in the metallic melt may include, but are not limited to, films, skins and / or inclusions, for example of a metal and / or an oxide that form from oxidation of the melt. In this regard, an oxide film (skin) can still form within the high temperature receptacle that envelops the outer surface of the molten metal therein, as well as resultant oxides formation in the melt.

[0021] In those examples that include a filter, the filter may be configured to remove impurities of a selected size relating to the sizing of the filter, for example the pore size or aperture size of that filter. In this sense, the filter functions to remove impurities from the metallic melt before the metallic melt egresses through the nozzle aperture. The filter separates these impurities (e.g. oxide skin, film, and / or inclusions as noted above) from the metallic melt flowing through the filter, preventing this material from being included in the formed metallic film which could otherwise result in defects such as pinholes, and / or blocking the nozzle aperture. The impurities are left behind as a filtride on the flow entry side (e.g. upper) of the filter.

[0022] The filter may have various configurations which are permeable to the metallic melt but filter selected materials from the molten material. Inembodiments, the filter may comprise a separator body that facilitates fluid flow through the filter via at least one pore, aperture, permeable structure, or the like. In some embodiments, each filter may comprise a separator body that includes at least one aperture, preferably a plurality of apertures. In embodiments, the separator body comprises a solid body, for example a plate or sheet, such as a ceramic plate, or a ceramic coated plate, which includes said at least one aperture. Nevertheless, it should be appreciated that other filter embodiments may be possible, for example a strainer or sieve configuration, or high temperature materials that have a selected permeability and / or porosity.

[0023] The apertures in the filter may comprise through-apertures or through- holes that form a fluid passage through the filter. The apertures may have any suitable configuration for example, slots, circular, oval, square, rectangular or other polygonal shapes, preferably regular polygonal shapes. In some embodiments, the apertures in the filter comprise circular through-holes. The apertures can play an important role in determining flow and thermal distribution of the metallic melt when passing therethrough. In embodiments, at least one of the size, location and number of apertures in the filter are configured to provide a substantially uniform flow of metallic melt when metallic melt flows through the at least one aperture.

[0024] The size and the number of the apertures in the filter can be designed to maximise flow rate of the metallic melt flowing through the filter (reducing time of heat loss), while ensuring retention of filtride. The locations of the apertures may be configured to deliver the incoming metallic melt uniformly into the chamber or space into which the metallic melt flows into. In this regard, the metallic material may not be fully melted if the size of the apertures is too large. However, the metallic melt may be overheated if the size of the apertures is too small. In some embodiments the size of each aperture is from 3 mm to 5.5 mm. For example, in a melt-delivery arrangement for fabricating Ni-Ti shape memory alloy foils, there are 9 holes evenly distributed across the planar surface of a 30 mm diameter filter. The size of each hole may be from 3 mm to 5.5 mm. The cross-sectional shape of the apertures may have any suitable shape which enable uniformdelivery of the metallic melt through each filter. Examples of cross-sectional shapes of the apertures may include circular, oval, square, rectangular or the like.

[0025] A uniform flow distribution of metallic melt through the filter may be facilitated by configuring the filter with apertures that are substantially evenly distributed across the planar area perpendicular to the longitudinal axis of each filter. In embodiments, the apertures may be substantially evenly distributed across the lateral or planar area that is perpendicular to the longitudinal axis of each filter when the filter is located within the at least one chamber. This substantially even / even distribution of apertures across the filter assists in providing a uniform temperature distribution of the metallic melt to the nozzle, and thus minimising and preferably preventing cold spots around the nozzle opening in the nozzle.

[0026] The filter may be located between fluid holding spaces of the at least one chamber and facilitates fluid transfer (i.e. , of the metallic melt) between those fluid holding spaces via the at least one aperture of each filter. Embodiments of the high temperature receptacle can include two, three, four, or more chambers as will be described in more detail below.

[0027] The melt delivery arrangement may not necessarily be limited to having a single filter. In some examples, the high temperature receptacle may comprise at least two filters located within the at least one chamber. The use of two or more filters may allow these filters to have different filter structures, such as different aperture sizes, different porosity, different permeability or the like.

[0028] For example, where each filter comprises a separator body that includes at least one aperture, the apertures of each filter of the at least two filters may have different aperture sizes. In this respect, the filters may be configured to include different sized apertures, with the first filter having larger apertures to the second filter. The first filter may therefore remove impurities and inclusions from the metallic melt of a certain size. The second filter (or filters if there are more than two) may have apertures that may be sized to remove any smaller impurities and / or inclusions from the metallic melt that may have passed through the first filter. As noted above, where two or more filters are used, an intermediary filterchamber may be included which defines a space between axially adjacent filters, providing a space where the metallic melt can pass, and a space where the filtride e.g. the separated impurities such as inclusions, films etc., are held which do not pass through the at least one aperture of the relevant filter. In some embodiments, the intermediary filter chamber may be a temperature-controlled chamber.

[0029] The metallic material within the at least one chamber of the high temperature receptacle may be heated above the melting point of that metallic material using a heating arrangement. The nozzle may also be pre-heated using the same or different heating arrangement. The melt-delivery arrangement may therefore further comprise at least one heating arrangement operatively associated with the high temperature receptacle, configured to heat the metallic material within the high temperature receptacle to at least the melting point of that metallic material. Again, the at least one heating arrangement may also pre-heat the nozzle to a selected temperature.

[0030] A variety of heating arrangements may be used. In many planar flow casting arrangements, inductive heating may be used to heat the metallic material in the melt delivery arrangement. One or more of the at least one heating arrangements can therefore preferably comprises an induction heating unit. Thus, in embodiments, one or each of the heating arrangements may comprise at least one heating or induction coil which extends over the high temperature receptacle. The at least one heating or induction coil may extend to the nozzle. The length of the nozzle and the induction coil may be designed in such way that the nozzle can be inside the hot zone of the coil, so it can be sufficiently preheated while being empty. It is noted that excessive heat loss at the nozzle aperture, where the temperature is the lowest, would solidify the melt partially or fully blocking the nozzle opening.

[0031] In embodiments, oxidation of the high-temperature (e.g. non-ferrous) metallic melt within the melt-delivery arrangement may be aimed to be mitigated and minimised. The high temperature receptacle may be configured to be flushed and filled with an inert gas atmosphere. This may be achieved in embodimentsby the melt-delivery arrangement being configured to be operated housed within an atmosphere-controlled chamber which may be configured to flush and / or fill the high temperature receptacle with an inert gas atmosphere. A number of inert gases may be used in this arrangement. For example, the inert gas atmosphere may comprise at least one of nitrogen, or a noble gas. In embodiments, the inert gas atmosphere is formed from one of nitrogen, argon, or neon. Preferably, the oxygen content of the inert gas atmosphere may be 50 ppm or less, preferably 30 ppm or less. The atmosphere-controlled chamber may be configured to substantially extract the gaseous atmosphere within the high temperature receptacle, and backfill with the inert gas atmosphere. In some embodiments, the melt-delivery arrangement may be located within a vacuum chamber configured to substantially extract the gaseous atmosphere within the high temperature receptacle, and backfill with the inert gas atmosphere. The inert gas atmosphere may be included within the high temperature receptacle any suitable pressure. In embodiments, the inert gas atmosphere may be included within the high temperature receptacle at a pressure of at least 0.3 bar, preferably at least 0.5 bar. However, it should be appreciated that other suitable pressures could be used depending on the desired operating conditions.

[0032] Metallic melt may be restricted from leaking through the nozzle before an ejection pressure is applied by establishing a static metallic melt over the whole width of the nozzle aperture. This static metallic melt may be produced through a combination of nozzle aperture sizing and temperature of the metallic melt therein to provide the required surface tension (skin friction) across the nozzle aperture. This stationary metallic melt enables the metallic melt to uniformly exit the nozzle when being ejected onto the surface of the rotating wheel, rapidly uniformly solidifying into defect-free full-width foils (i.e. foils which do not have defects such as pinhole defects or similar). This control may be realised by having a narrow width of the nozzle opening within fixed parameters.

[0033] The width of the nozzle aperture may influence the foil thickness. In some embodiments, the at least one nozzle aperture may comprise at least one slot or opening having a width from 0.1 to 1.2 mm, preferably from 0.2 to 1.2 mm, more preferably from 0.2 to 1.0 mm. In some embodiments, the at least one nozzleaperture comprises at least one slot or opening having a width from 0.4 to 1.2 mm, preferably from 0.5 to 1.0 mm. In preferred embodiments, the nozzle aperture may comprise a slot or slit, preferably an elongate slot. In embodiments, the nozzle aperture comprises elongate (lengthwise) narrow slit. The elongate slot or slit may have a width (perpendicular to the length) from 0.4 to 1.2 mm, preferably from 0.5 to 1.0 mm.

[0034] The length of the nozzle aperture may correspond with the width of the metallic film that is being cast. As can be appreciated, this can be any suitable length. In embodiments (e.g. forTi based alloys), the length of the nozzle aperture may be at least 10 mm, preferably at least 20 mm. In some embodiments, the length of the nozzle aperture may be from 15 to 40 mm, preferably from 20 to 30 mm. In other embodiments (e.g. for amorphous ferrous based alloys, such as amorphous steel), the length of the nozzle aperture may be from 100 to 500 mm, preferably 200 to 300 mm.

[0035] In some examples, the high temperature receptacle may include any number of chambers. Embodiments of the high temperature receptacle may include one, two, three, four, or more chambers. In some embodiments, a single main metallic melt holding chamber may be provided which fluidly links to the at least one filter, and through to the nozzle. In other embodiments, the high temperature receptacle may include two or more chambers which are separated by a filter. In embodiments, the high temperature receptacle may include at least two chambers separated by the at least one filter and a longitudinal axis extending therethrough, said at least two chambers including: a melt chamber comprising a fluid holding space configured to hold a metallic melt therein; and a distribution chamber located axially below the melt chamber relative to the longitudinal axis, which includes a fluid holding space configured to hold a metallic melt therein, and a base that includes the nozzle, wherein the at least one filter is located between the melt chamber and the distribution chamber.

[0036] In these embodiments, the melt-delivery arrangement may merge a melting crucible (the melt chamber) and a separate nozzle (the distribution chamber) into a single receptacle. The two-chamber arrangement may enable a two-step - melting and melt-delivery - process to be conducted in a single meltdelivery arrangement. Here, the melt chamber may be configured to allow the metal or alloy to melt and / or become molten when heated in that chamber above the melting point. The distribution chamber may function to deliver and substantially evenly distribute a filtered molten material through the nozzle aperture / slot onto a foil formation surface to form the metallic foil.

[0037] The filter in these embodiments may be located between the fluid holding spaces of the melt chamber and the distribution chamber, and facilitates fluid transfer (i.e., of molten metal) between the fluid holding spaces of the melt chamber and the distribution chamber via the at least one aperture of each filter. It should be noted that the fluid holding space in the distribution chamber may be defined between the base of that chamber and the at least one filter. The fluid holding space in the melt chamber may extend axially above the at least one filter relative to the longitudinal axis of the high-temperature receptacle.

[0038] The planar flow casting melt-delivery arrangement may be configured to control melt flows within the distribution chamber and / or nozzle. This control may include the re-distribution of the melt from the melt chamber to and through the distribution chamber with the aim to distribute the metallic melt flows across (preferably in a uniform flow across) the entirety of the at least one nozzle aperture. In particular configurations, the melt chamber may have a narrower dimension, for example width, compared to the distribution chamber and the nozzle (and the at least one nozzle aperture) at the base of that distribution chamber. In such embodiments, it may be advantageous to control melt flows through the distribution chamber and nozzle to assist a uniform flow to be distributed across the width the distribution chamber, and to distribute the metallic melt so that it flows across the entirety, for example whole length, of the at least one nozzle aperture. This then may be used to minimise non-uniform metallic flows when the metallic melt exits the nozzle aperture.

[0039] In some embodiments, the at least one filter may be configured to provide a flow distribution function. In other embodiments, the arrangement may also include at least one flow distributer which may be configured to distribute or otherwise control the flow within the at least chamber so that the metallic melt flows across the entirely, for example whole length, of the at least one nozzle aperture. In some examples, the planar flow casting melt-delivery arrangement may further comprise at least one flow distributor located between the filter and the at least one nozzle aperture. The at least one flow distributor may be configured to re-distribute the metallic melt flows and minimise their nonuniformity and variation. In embodiments, the at least one flow distributor may be located within the distribution chamber, preferably spaced apart from the at least one nozzle aperture.

[0040] In those embodiments that include at least a flow distributor, the flow distributor may be configured to control the flow related to the foil width. For example, the number of apertures, the position of the apertures, and the size of the apertures in each flow distributor may be varied and optimised. The combination of these features may be used to distribute (and thus provide control) the metallic melt so that the metallic melt flows across (preferably in a uniform flow across) the entirely, for example whole length, of the at least one nozzle aperture. This control may be utilised to deliver a selected (and controlled) flow rate and temperature of the melt at the nozzle aperture that may be designed to form quality thin foils, thereby minimising the inconsistency of thickness and properties of the produced foil. In embodiments, the flow distributor may be configured to allow the metallic melt to flow from the melt chamber, to the at least one flow distributor, where the metallic melt travels on or over the top of the at least one flow distributors before passing through the at least one aperture in the flow distributor, towards the at least one nozzle aperture.

[0041] In embodiments, large widths foils may be produced using a planar flow casting melt-delivery arrangement of this first aspect in a configuration where the width of the distribution chamber and the at least one nozzle aperture may be greater than the width of the melt chamber. In other words, the at least nozzle aperture, for example configured as a slit or slot type aperture, may be wider thanthe width of the melt chamber. The width of the at least one nozzle aperture may be selected to provide the desired dimension of the desired large width foil. In these embodiments, the distribution chamber may comprise at least two sections of different widths, said widths of the at least two sections providing a channel between x the melt chamber to the at least one nozzle aperture that transitions to that larger width size.

[0042] For large-width foils (for example foils having a width of 30 mm or more, such as 30 to 300 mm or more), the distribution chamber may be formed in two sections, with each section separated by the flow distributor. In some embodiments, the distribution chamber may include an upper section located above the flow distributor relative to the at least one nozzle aperture having a first cross-sectional shaped chamber (e.g. circular or other polygon shaped crosssection) and a lower section located below the flow distributor relative to the at least one nozzle aperture which comprises a second cross-sectional shaped chamber that has a different cross-section to the first cross-sectional shaped chamber, that second cross-sectional shaped chamber may be configured to conform with and / or extends around the shape of the at least one nozzle aperture. That lower section may comprise a nozzle section (forming part of the nozzle), configured as a funnel which directs flow towards the at least one nozzle aperture. The function of the lower section of the distribution chamber (or nozzle section) in such embodiments may be to provide a flow distributor and / or funnel for the flow to be distributed across the entire extended length of the at least one aperture. In embodiments, the lower section may comprise a funnel that is configured to direct flow (e.g. of the metallic melt) toward the final shape, for example elongated shape (e.g. elongate slot for a large-width foil nozzle aperture), of the at least one nozzle at the base of the distribution chamber.

[0043] In those embodiments where the at least one nozzle aperture comprises an elongate slot or slit, and the length of that elongate slot is greater than the width of the melt chamber, the lower section of the distribution chamber (nozzle section) may be configured to transition from a first cross-section (e.g. circular or other polygon shaped cross-section) corresponding to the upper section of the distribution chamber to a second cross-section that may be configured to conformwith and / or extends around the shape of the at least one nozzle aperture. In some embodiments, that transition may be a sharp transition, for example, the lower section may comprise that second cross-section immediately after the flow distributor. In other embodiments, that transition may be progressive, with the change in cross-sectional area being staged, stepped or otherwise sloped following the flow distributor moving axially towards the at least one nozzle aperture. Again, the function of the lower section of the distribution chamber in such embodiments may be to provide a funnel for the flow to be distributed across the entire extended length of the at least one aperture. This may be particularly advantageous when the at least one aperture comprises an elongate slot or slit.

[0044] In some embodiments, the distribution chamber, preferably the lower section of the distribution chamber (or nozzle), may comprise at least two tiered sections of different widths, said widths of the at least two tiered sections providing a progressively larger width size from the melt chamber to the at least one nozzle aperture. Each tiered section may include at least one flow distributor. In this configuration, the flow distributor in each tiered section may be configured to control and distribute melt flows through that tiered section of the distribution chamber, to assist a uniform flow to be distributed across the expanded width of that tier of the distribution chamber, and may thereby distribute the metallic flow across the whole length of the at least one nozzle aperture. Again, this may be used minimise non-uniform metallic flows when the metallic melt exits the nozzle aperture.

[0045] In some embodiments, the distribution chamber may include an upper section above the flow distributor comprising a cylindrical (circular cross-section) or other polygonal cross-sectional shaped chamber and a lower section which comprises different cross-sectionally shaped chamber, for example an elongate chamber, such as a generally rectangular shaped chamber, that may extend around and may lead to the at least one nozzle aperture. Melt flows into this lower section (the nozzle), through the flow distributor into the lower section which may be shaped to funnel or otherwise direct the melt towards the elongate (slot) nozzle aperture. In those embodiments with tiered sections, each tiered section may itself be configured, and / or have a lower chamber that may be shaped tofunnel or otherwise direct the melt towards the following section in the distribution chamber.

[0046] The at least one flow distributor may have various configurations which are permeable to the metallic melt but filter selected materials from the molten material. In embodiments, the flow distributor may comprise a separator body that facilitates fluid flow through the filter via at least one pore, aperture, permeable structure, or the like. In some embodiments, each flow distributor may comprise a separator body that includes at least one aperture, preferably a plurality of apertures. In embodiments, the separator body may comprise a solid body, for example a plate or sheet, such as a ceramic plate, or a ceramic coated plate, which includes said at least one aperture. Nevertheless, it should be appreciated that other flow distributor embodiments may be possible, for example a strainer or sieve configuration, or high temperature materials that have a selected permeability and / or porosity.

[0047] In embodiments, the at least one flow distributor may comprise a separator body, for example a ceramic plate or sheet, that includes at least one aperture. The at least one aperture may be configured to be aligned or otherwise positioned in a location that is favourably positioned relative to the alignment of the at least one nozzle aperture within the high temperature receptacle. For example, the at least one aperture of each flow distributor may be aligned with the at least one nozzle aperture. In those embodiments comprising at least two apertures, those apertures may be linearly aligned with the at least one nozzle aperture. In these embodiments, the apertures may be aligned in a configuration that distributes the metallic melt flows across (preferably in a uniform flow across) the whole length of the at least one nozzle aperture.

[0048] The apertures in the at least one flow distributor may comprise through- apertures or through-holes that form a fluid passage through the flow distributor. The apertures may have any suitable configuration for example, slots, circular, oval, square, rectangular or other polygonal shapes, preferably regular polygonal shapes. In some embodiments, the apertures in the flow distributor may comprise circular through-holes. The apertures may play an important role indetermining flow and thermal distribution of the metallic melt when passing therethrough. In embodiments, at least one of the size, location and number of apertures in the distributor are configured to provide a substantially uniform flow of metallic melt when metallic melt flows through the at least one aperture. Again, the apertures may be aligned in a configuration that distributes the metallic melt flows across (preferably in a uniform flow across) the whole length of the at least one nozzle aperture.

[0049] A uniform flow distribution of metallic melt through the flow distributor may be facilitated by configuring the flow distributor with apertures that are substantially evenly distributed across the planar area perpendicular to the longitudinal axis of each flow distributor. In embodiments, the apertures may be substantially evenly distributed across the lateral or planar area that is perpendicular to the longitudinal axis of each flow distributor when the distributor is located within the distribution chamber. This substantially even / even distribution of apertures across the flow distributor assists in providing a uniform temperature distribution of the metallic melt to the nozzle, and thus minimising and preferably preventing cold spots around the nozzle opening in the nozzle.

[0050] The melt delivery arrangement may not necessarily be limited to having a single flow distributor. The planar flow casting melt-delivery arrangement may have any number of flow distributors. In some embodiments, the planar flow casting melt-delivery arrangement / high temperature receptacle may include at least two flow distributors. Each flow distributor may be spaced apart within the distribution chamber between the filter and the at least one nozzle aperture. The use of two or more flow distributors may allow these flow distributors to have different structures or configurations, such as different aperture sizes, different porosity, different permeability or the like. In some embodiments, the at least two flow distributors may be configured to assist in a progressive flow distribution where there is a large change in width or dimension from the melt chamber to the at least one nozzle aperture.

[0051] For example, where each flow distributor comprises a separator body that includes at least one aperture, the aperture of each flow distributor of the at leasttwo distributors have different aperture sizes, positions and number of apertures. The first flow distributor may have a greater width than the melt chamber but smaller width than the width of the at least one nozzle aperture, and the second flow distributor may have a greater width than the first flow distributor and be close in width / dimension to the width of the at least one nozzle aperture. The increase in the distributor width enables to distribute the melt flow smoothly to the full size of the foil width when the width of the at least one nozzle aperture is significantly larger than the width of the melt chamber.

[0052] Where a heating arrangement is provided, the heating arrangement may be configured to heat the metallic material within the high temperature receptacle, and more particularly the melt chamber and / or the distribution chamber to at least the melting point of that metallic material. Where the heating arrangement comprises at least one heating or induction coil, the at least one heating or induction coil may extend over the melt chamber to the distribution chamber, and in in those embodiments that include a nozzle, may extend to the nozzle of the distribution chamber. The length of the nozzle and the induction coil may be designed in such way that the distribution chamber of the nozzle can be inside the hot zone of the coil, so it may be sufficiently pre-heated while being empty. The at least one heating arrangement may be configured to heat the metallic material within one or both of the melt chamber and the distribution chamber to at least the melting point of that metallic material. In most embodiments, the heating arrangement may be configured to heat both the melt chamber and the distribution chamber. The at least one heating arrangement may preferably be configured to heat the metallic material within the melt chamber and the distribution chamber to at least the melting point of that metallic material.

[0053] In some embodiments, the at least one heating arrangement may be configured to independently heat the melt chamber and the distribution chamber. Here, the at least one heating arrangement may comprise at least two heating arrangements including a first heating arrangement operatively associated with the melt chamber, and a second heating arrangement operatively associated with the distribution chamber. Each of the melt chamber and the distribution chamber may have separate heating arrangements configured to heat the metallic materialthat chamber to at least the melting point of that metallic material. The use of separate heating arrangements may allow independent control of heating of the melt and distribution chambers and thus, where necessary, control of the heating temperature, which may be required or desired to be different.

[0054] It should be appreciated in those embodiments where the distribution chamber includes an upper section and a lower section comprising a nozzle providing a flow distributor and / or funnel for the metallic melt, the least one heating arrangement may comprise at least two heating arrangements including a first heating arrangement operatively associated with the melt chamber and optionally with the upper section of the distribution chamber, and a second heating arrangement operatively associated with the lower section of the distribution chamber - the nozzle. Those at least two heating sections may be configured / shaped to conform with the configurations of the melt chamber and lower section of the distribution chamber - i.e. nozzle. For example, where the nozzle (lower section of the distribution chamber) has a rectangular cross- sectional shape and the melt chamber has a circular cross-sectional shape, the at least two heaters may comprise a circular heater used for the melt chamber cylinder and a separate rectangular heater for the rectangular shape nozzle.

[0055] In some embodiments, the melt delivery arrangement may include two chambers, comprising the melt chamber and the distribution chamber. In other embodiments the at least two chambers may include two or more melt chambers, two or more parallel distribution chambers, or further chambers, such as intermediary filter chambers that are included where two or more filters may be included between fluidly connected melt chambers and distribution chambers.

[0056] The high temperature receptacle may have any suitable shape and / or configuration. In some embodiments, the high temperature receptacle comprises a cylindrical shaped container. However, it should be appreciated that the high temperature receptacle may have any shape, including cube, cuboid, prism (such as a triangular prism), or other shapes having a polygonal cross-section including (but not limited to) square, rectangular, hexagonal, or other polygonal, preferably regular polygonal shapes.

[0057] The high temperature receptacle may be any suitable high temperature metallic melt holding container. In many embodiments, the high temperature receptacle may comprise a crucible, preferably a carbonaceous, refractory or high-temperature ceramic crucible. The material of construction of the high temperature receptacle may typically be chosen to withstand high temperatures and thermal shock, and to preferably not react with the molten metals. Suitable materials may include quartz, boron nitride, aluminium oxide, graphite and other refractory materials. In embodiments, the high temperature receptacle may be formed from aluminium oxide or graphite, preferably including an inner coating or lining of an inert refractory material (see below); AIN; shock resistant refractory metals such as Ta, W, Mo coated with inert materials (such as Y2O3); or ceramic composites like BaZrCh and CaO-doped BaZrOs. It should be appreciated that the selection of a suitable high temperature material includes considerations of melting point compared to the metallic material to be melted therein, reactivity, temperature stability and mechanical properties. These factors would be understood by those skilled in the art, who would be able to specify a suitable high temperature material, for example from the materials noted above. In embodiments, the high temperature receptacle comprises a carbonaceous based container, and preferably a graphite crucible.

[0058] The high temperature receptacle can be formed from a combination of materials. For example, the at least one chamber may include an inner high- temperature ceramic layer in some embodiments. In applicable embodiments, at least the melt chamber, and preferably both the melt chamber and the distribution chamber may include an inner high-temperature ceramic layer. This high- temperature ceramic layer may be used as a protective layer, separating the out layer or shell from the molten metal. A protective layer of this type may be advantageous as many molten metals, particularly molten metals containing Ti, tend to react with a carbonaceous based crucible, producing reaction products that could cause the formation of pinhole defects in the foils, or even lead to blockage of the nozzle aperture of the melt delivery arrangement.

[0059] In many embodiments, the high-temperature ceramic layer may be selected to have low wetting properties to the metallic melt. In this sense, the high-temperature ceramic materials used for the inner layer may be selected to be less wetting to the metallic melt compared to a non-wetting material used in the receptacle (for example carbonaceous materials, such as graphite), thus minimising the reaction between the molten metals and the containment materials. It is to be understood that low wetting properties refer to the wettability of that surface to the metallic melt i.e., the character of a given material, that allows liquids to adhere to its surface. A low wetting material has higher adherence of the liquid to the material, promoting droplet formation thereon, as opposed to the material spreading out over the surface.

[0060] The inner high-temperature ceramic layer may have any suitable configuration. For example, the high-temperature ceramic layer may comprise one of a coating, lining, cladding or insert. Thus, in some embodiments, the high temperature receptacle may comprise a carbonaceous based outer wall, for example a graphite material and an inner high-temperature ceramic coating, layer or lining. In some embodiments, the ceramic layer may comprise a coating that may be applied to a base material forming the high temperature receptacle. In other embodiments, the ceramic layer may comprise an insert that may be fitted into the base material forming the high temperature receptacle.

[0061] The inner high-temperature ceramic layer may have any suitable composition. In embodiments, the high-temperature ceramic layer comprises at least one high temperature ceramic, preferably selected from at least one of: aluminium oxide (AI2O3), quartz, boron nitride (BN), or yttrium oxide (Y2O3), AINi or, a refractory oxide. In some embodiments, the high-temperature ceramic layer may comprise at least one of: boron nitride (BN), or yttrium oxide (Y2O3), preferably at least one boron nitride (BN) layer and at least one layer of yttrium oxide (Y2O3), and more preferably at least two boron nitride (BN) layers and at least one layer of yttrium oxide (Y2O3).

[0062] Heat loss efficiencies within the high temperature receptacle may be made through heat loss design considerations of the structure and material thereof. For example, the base of the high temperature receptacle (which may include thenozzle) may be constructed with a lower heat capacity compared to the sidewalls of the high temperature receptacle. Practically, this may be embodied in the high temperature receptacle by designing the base of the high temperature receptacle with a thinner wall thickness to sidewalls of the high temperature receptacle. For example, the bottom of the high temperature receptacle can be designed to have thin wall thickness, for example be only 1 mm thick, mitigating the possibility that a thick nozzle bottom may act as a heat sink absorbing heat from the molten metal, and therefore solidifying metal within the nozzle.

[0063] The melt-delivery arrangement may be used to produce a large variety of metallic foils of various compositions. Exemplary metallic materials that may benefit from planar flow casting using the the melt-delivery arrangement include (but are not limited to) precision thin metal and alloys, shape memory alloys, or crystalline or amorphous metals and / or alloys. These metallic materials may comprise one or more high-melting-temperature nonferrous alloy. Specific examples include stainless steels; crystalline and amorphous steels, crystalline and amorphous, Zr, Mg, Ti, Cu, or the like based or containing alloys; or a nonferrous or ferrous alloy made from or alloyed with at least one of: titanium (Ti), nickel (Ni), vanadium (V), cobalt (Co), copper (Cu), aluminium (Al), Zirconium (Zr), neodymium (Nd) or other rare earth elements. One exemplary example of a suitable nonferrous alloy is titanium (Ti) based alloys and / or Ti containing alloys.

[0064] In embodiments, the melt-delivery arrangement may be used to produce metallic foils using and / or from recycled metals or metal alloys. In these embodiments, the metallic material may comprise at least one recycled metal or metal alloy. Use of the melt-delivery arrangement for forming foils using recycled metal or alloy may be advantageous given the potential to remove oxides and other inclusions from the melt prior to forming the foil.

[0065] The melt-delivery arrangement may be utilised in any suitable planar flow casting machine. In many embodiments, the planar flow casting machine may include a casting / chill wheel, an induction heating unit, and an atmosphere- controlled chamber which houses the melt-delivery arrangement therein.

[0066] A second aspect provides a planar flow casting system comprising:a planar flow casting melt-delivery arrangement according to the first aspect; and a foil formation surface operatively associated with the planar flow casting melt-delivery arrangement onto which the metallic melt is distributed from the nozzle of the melt-delivery arrangement for foil formation.

[0067] It should be appreciated that this second aspect can take all the features described above for the first aspect.

[0068] The foil formation surface may comprise any suitable chill arrangement (also known as a quenching arrangement) that is configured to form a foil via planar flow casting. In embodiments, the foil formation surface may comprise a chill surface (also known as a quenching surface). Here, the foil formation surface typically forms the outer surface of a movable chill surface, or alternatively the outer surface of a rotatable cylinder or belt. The chill surface may be substantially flat, such as a belt, preferably endless belt, or it may be an annular chill roll. In embodiments, the rotatable cylinder may comprise a quenching / chilling wheel.

[0069] As described above for the first aspect, the high temperature receptacle of the planar flow casting melt-delivery arrangement may be housed within an atmosphere-controlled chamber that is configured to flush and / or fill the high temperature receptacle with an inert gas atmosphere. A number of inert gases can be used in this arrangement. For example, the inert gas atmosphere can comprise nitrogen and / or a noble gas. In embodiments, the inert gas atmosphere may be formed from one of nitrogen, argon, or neon.

[0070] In embodiments, the method may further comprise passing the metallic melt through at least one flow distributor located within the high temperature receptable to redistribute the filtered metallic melt within the high temperature receptable. As described for the first aspect, the at least one flow distributor may be configured to minimise non-uniformity and variation of the metallic flow prior to passing through the at least one nozzle aperture.

[0071] A third aspect provides a planar flow casting method of forming a metallic foil. The method may comprise forming a metallic melt of a metallic material within a high temperature receptable. The method may comprise removing impurities from the formed metallic melt. The method may comprise then feeding the metallic melt through at least one nozzle aperture of the high temperature receptable for foil formation on a foil formation surface. In some examples, the method may comprise passing the metallic melt through at least one filter located within the high temperature receptable to remove impurities from the metallic melt flowing therethrough, e.g. so as to produce a filtered metallic melt to feed through at least one nozzle aperture of the high temperature receptable.

[0072] This third aspect provides a method of forming a metallic foil on a foil formation surface using the planar flow casting system of the second aspect. The system utilises a melt delivery arrangement, for example a melt delivery arrangement as described above for the first aspect, in a planar flow casting arrangement to distribute a metallic melt heated within that melt delivery arrangement onto a foil formation surface. As outlined in the second aspect, that foil formation surface may be a chill surface such as the outer surface of a rotatable cylinder or belt.

[0073] The metallic melt may be formed within the high temperature receptable using a number of means and methods. In embodiments, the metallic material may be heated within the high temperature receptable to at least the melting point of the metallic material, to form the metallic melt. In these embodiments, the metallic melt may be heated in the at least one chamber of the high temperature receptacle using a heating arrangement operative associated with the meltdelivery arrangement. As explained for the first aspect, examples of the planar flow casting melt-delivery arrangement may include at least one heating arrangement operatively associated with the high temperature receptacle, configured to heat the metallic material within the high temperature receptacle to at least the melting point of that metallic material to form the metallic melt. A variety of heating arrangements may be used. Inductive heating may be used in many planar flow casting arrangements to heat the metallic material in the hightemperature receptacle. The at least one heating arrangement may therefore comprise an induction heating unit.

[0074] An overheat may be desired to keep the alloy molten when flowing through the apertures of the filter, and remain molten once the metallic melt has passed through the filter. The required overheat may be related to the melting point of the metallic material, and the size, number and distribution of the apertures in filter. For example, 3 mm diameter holes may be adequate to achieve a required superheat for high-temperature alloys having a melting point between 1300 °C and 1800 °C. In embodiments, heat loss in the nozzle section of the high temperature receptacle may be optimised / minimised which can be utilised to enable the metallic melt within the at least one chamber of the the high temperature receptacle to have a small superheat - i.e., leading to lower oxidation contamination. The metallic material in the high temperature receptacle may be preferably heated to a temperature of at least 5 degrees (in Celsius), preferably at least 10 degrees above the melting point of the metallic material. In many cases, a 5 to 20 degree C overheat may be sufficient.

[0075] That metallic melt may be supplied into the high temperature receptacle as a molten melt, or more typically the metallic melt may be formed within the high temperature receptacle by melting a solid material, such as metallic ingot or other metallic body therein. In these embodiments, the metallic material may comprise a solid prior to heating in the high temperature receptacle. In those embodiments that include a melting chamber, the melt chamber of the meltdelivery arrangement may be used to form and / or hold that metallic melt prior to passing through the filter or filters.

[0076] As described above for the first embodiment, the high temperature receptacle may be filled with an inert gas prior to forming a metallic melt. The inert gas atmosphere reduces the amount of oxygen within the high temperature receptacle, so to reduce oxidation of the metallic melt held therein. In these embodiments, the method of this second aspect may further comprises the step of:forming an inert gas atmosphere within the high temperature receptacle prior to forming the metallic melt within the high temperature receptable.

[0077] As with the first embodiment, the high temperature receptacle may be housed within an atmosphere-controlled chamber which is operated to form an inert gas atmosphere, with an oxygen content of 50 ppm or less, preferably 30 ppm or less. This reduces, mitigates and / or minimises oxidation of the metallic melt within the high temperature receptacle. The inert gas atmosphere may comprise at least one of nitrogen, or a noble gas, preferably nitrogen, argon, or neon. The inert gas atmosphere may be formed with a pressure of at least 0.3 bar, preferably at least 0.5 bar. As with the first aspect, the atmosphere- controlled chamber may be configured to substantially extract the gaseous atmosphere within the high temperature receptacle, and backfill with the inert gas atmosphere. In some embodiments, the melt-delivery arrangement may be located within a vacuum chamber configured to substantially extract the gaseous atmosphere within the high temperature receptacle, and backfill with the inert gas atmosphere. In embodiments, the atmosphere-controlled chamber may be operated to remove the atmosphere in the high temperature receptacle to 200 millitorr (3x1 O'4bar), and then introduce an inert gas atmosphere. For example, that inert gas atmosphere may comprises a high purity argon (Ar) atmosphere or other inert gas, and has a pressure of between 0.3 and 0.4 bar, preferably about 0.34 bar. However, it should be appreciated that other pressures may equally be used.

[0078] As an example, in some embodiments, this may involve three cycles of firstly vacuuming the atmosphere-controlled chamber to 3x1 O'4bar and then back-filling of high purity argon (Ar), to 0.5 bar to reduce the oxygen level inside the atmosphere-controlled chamber to 30 ppm or less. Once a low oxygen level is achieved7the atmosphere-controlled chamber is backfilled one last time with high purity Ar to about 0.34 bar being ready for commencing heating the metallic material to at least the melting point of that metallic material.

[0079] Once the metallic melt is at or slightly above (for example a 5 to 20 degree overheat as indicated above) its melting temperature, the metallic melt may beallowed to flow through the filter. The control of this metallic melt flow through the at least one aperture of the filter may be through at least one of: temperature control; or pressure control. In some embodiments, the metallic melt may be allowed to flow through the at least one aperture of the filter which may be controlled by surface tension in the metallic melt across the aperture(s) in the filter. When the metallic melt reaches a certain temperature, typically the overheat temperature, the arrangement may be designed to allow the metallic melt (also known as a molten alloy) to flow through the at least one aperture of the filter (as indicated above). In other embodiments, an overpressure may be required to enable the metallic melt to flow through the at least one aperture of the filter (depending on the aperture size and distribution). This can be achieved for example by increasing the pressure in the high temperature receptacle, such as by increasing the pressure in the vacuum chamber by at least 0.05 bar, more preferably at least 0.10 bar.

[0080] The completion of the melt transferring may be indicated by the melt temperature become flat or even decreases, signalling the start of the second step of the melting process in the lower nozzle chamber. This melt temperature may be measured by various means, for example using a pyrometer or other temperature sensor.

[0081] Heat loss in the system may be mitigated through a number of heat transfer considerations. In some embodiments, the method may further comprise preheating the nozzle and surrounding sections of the high temperature receptacle to at least the melting temperature of the metallic material prior to the metallic melt flow through the at least one aperture of the filter. In this sense, heat loss in the nozzle and surrounding sections of the high temperature receptacle may be minimised by the nozzle and surrounds being pre-heated uniformly to a higher temperature, minimising heat sinking.

[0082] In addition, heat loss in the melt-delivery arrangement of some embodiments may be reduced or minimised compared to conventional meltdelivery arrangements through the use of a dual chamber configuration of the high temperature receptacle, which merges the melting crucible (melt chamber inthe two chamber embodiment) and traditional separate nozzle (the distribution chamber in the two chamber embodiment) into a single receptacle. The elimination of the mass of a separate nozzle by this design may therefore play an advantageous role in minimising the heat loss and heat sinking. It should however be appreciated that this may not be applicable to all embodiments, for example when casting foils of >30 to 50 mm in width.

[0083] A step (e.g., the final step) before foil formation on the foil formation surface is egress of the metallic melt from the high temperature receptacle through the nozzle aperture onto the foil formation surface. This process usually requires an overpressure or ejection pressure to be applied to force the metallic melt through that nozzle aperture. The pressure may be created by the metallic melt head or pressurised inert gas. In embodiments, the metallic melt may be fed from the at least one chamber of the high temperature receptacle, through the at least one nozzle aperture for foil formation on the foil formation surface though the application of an ejection pressure. The ejection pressure may comprise any suitable pressure differential. In some embodiments, the ejection pressure may comprise 0.4 to 0.7 bar, preferably 0.5 to 0.6 bar. In other embodiments, the ejection pressure may comprise 4 to 7 bar, preferably 5 to 6 bar.

[0084] Prior to metallic metal egress through the nozzle aperture, the metallic melt may be held for a short holding time within the high temperature receptacle. In embodiments, the metallic melt may be held within the high temperature receptacle for a holding time of between 4 to 15 seconds, preferably 4 to 10 seconds before being fed through the at least one nozzle aperture for foil formation on the foil formation surface. As explained above, the metallic melt may be held from egress through the nozzle aperture by surface tension and / or pressure. A short holding time within the high temperature receptacle enables the temperature distribution of the metallic melt to be uniform to prevent cold spots around the nozzle aperture in the bottom of the nozzle. The section of the high temperature receptacle around the nozzle may be heated or not heated by the at least one heating arrangement during that short holding time. In some embodiments, the metallic melt may not be heated when being held within thehigh temperature receptacle before being fed onto the foil formation surface. The melt-delivery arrangement may be lowered to the foil formation surface whilst the metallic melt is held within the high temperature receptacle, with the nozzle opening being spaced apart a selected deposition distance from the foil formation surface, for example from 0.1 to 1.0 mm (e.g. 0.7 mm). As-the nozzle is positioned at the selected deposition distance from the foil formation surface (a small gap), the argon pressure in the high temperature receptacle is increased to the ejection pressure, for example set at 0.50 bar (compared to the vacuum chamber pressure of about 0.34 bar (i.e. , 0.16 pressure difference)).

[0085] The planar flow arrangement of the second aspect and the method of the third aspect may be used to produce a large variety of metallic foils of various compositions. Exemplary metallic materials that can benefit from the disclosed planar flow casting system and method include (but are not limited to) precision thin metal and alloys, shape memory alloys, or crystalline or amorphous metals and / or alloys. These metallic materials may comprise one or more high-melting- temperature nonferrous alloy. Specific examples include stainless steels; crystalline and amorphous steels, crystalline and amorphous, Zr, Mg, Ti, Cu, etc based or containing alloys; or nonferrous alloys or ferrous alloys made from or alloyed with at least one of: titanium (Ti), nickel (Ni), vanadium (V), cobalt (Co), copper (Cu), aluminium (Al), Zirconium (Zr), neodymium (Nd), or other rare earth elements. One exemplary example of a suitable nonferrous alloy is titanium (Ti) based or containing alloys.

[0086] The planar flow arrangement of the second aspect and the method of the third aspect may be used to produce metallic foils using and / or from recycled metals or alloys. In these embodiments, the metallic material may comprise at least one recycled metal or metal alloy. Use of the melt-delivery arrangement for forming foils using recycled metal or alloy may be advantageous given the potential to remove oxides and other inclusions from the melt prior to forming the foil.

[0087] The planar flow arrangement of the second aspect and the method of the third aspect may be used to produce metallic foils with a width and / or length that could not be previously produced by conventional planar flow cast methods. Afourth aspect provides a metallic foil produced by the method according to the third aspect. In embodiments, the produced metallic foil has a width of at least 10 mm, preferably at least 20 mm, more preferably at least 30 mm. In some embodiments, the planar flow cast metallic foil may have a width of at least 75 mm, preferably at least 100 mm, more preferably at least 250 mm. In some embodiments, the planar flow cast metallic foil may have a width of at least 300 mm. In embodiments, the metallic foil has a length of at least 300 mm, preferably a length of at least 500 mm, and more preferably a length of at least 1000 mm. In embodiments, the metallic foil has a length of from 1000 to 3000 mm. It should be appreciated that the length may have any suitable length depending on the rolling capability of the planar flow casting apparatus / arrangement, and may in some cases be 1 m, 5 m or 10 m, or more in length. In embodiments, e.g. stainless steel and non-ferrous alloys, the metallic foil may be produced with a thickness of less than 1.5 mm. In embodiments, the metallic foil has a thickness of from 10 to 200 pm, preferably 20 to 150 pm. In other embodiments, for example amorphous metal or alloy foils (e.g. amorphous steel), the metallic foil may be produced with a thickness of less than 5 mm, for example from 1 to 5 mm. In alternate embodiments, for example amorphous metal or alloy foils (e.g. amorphous steel), the metallic foil may be produced with a thickness of than 0.5 mm, for example from 0.01 to 0.5 mm, preferably less than 0.03 mm.

[0088] In embodiments, the planar flow cast metallic foil may be defect-free. As noted above, defect-free refers to a foil which does not have defects such as pin holes, oxide inclusions and / or other impurities, or similar defects. These type of defects can for example be included in the foil from the metallic melt when the foil is formed. For example, the planar flow cast metallic foil may be free of pinholes (and oxide inclusions) across the area of the foil.

[0089] In embodiments, the metallic foil may comprise a shape memory alloy foil, preferably a large-width shape memory alloy foil, for example a Nickel-Titanium (NiTi) shape memory alloy foil. Nickel-Titanium (NiTi) shape memory alloys (SMAs) are smart materials able to recover their original shape under thermal stimulus. SMA applications are possible in various areas, for example aerospace and defence, space technology, automotive, sensing and actuating, andbiomedical devices, renewable energy, industrial processing, and transport. The use of Ni-Ti SMAs is also possible in sensors, actuators, and other types of electronics.

[0090] In embodiments, the metallic foils may comprise an amorphous alloy thin foil, for example an amorphous steel thin foils which can be used for high efficiency electrical distribution transformer and electric motors.

[0091] The disclosed planar flow arrangement may advantageously produce planar flow cast metallic foil that could not be produced by conventional methods, particularly from particular metallic materials. A fifth aspect provides a planar flow cast metallic foil comprised of at least one of: a precision thin metal or alloy; a shape memory alloy; a stainless steel; a crystalline or amorphous metal or alloy (for example crystalline and amorphous steels, crystalline and amorphous, Zr, Mg, Ti, Cu, or the like based or containing alloys); or a nonferrous or ferrous alloy made from or alloyed with at least one of: titanium (Ti), nickel (Ni), vanadium (V), cobalt (Co), copper (Cu), aluminium (Al), Zirconium (Zr), neodymium (Nd) or other rare earth elements.

[0092] The planar flow cast metallic foil may, in embodiments, comprise at least one recycled metal or metal alloy.

[0093] In embodiments, the planar flow cast metallic foil may be defect-free. As noted above, defect-free refers to a foil which does not have defects such as pin holes, oxide inclusions and / or other impurities, or similar defects. These type of defects can for example be included in the foil from the metallic melt when the foil is formed. For example, the planar flow cast metallic foil may be free of pinholes (and oxide inclusions) across the area of the foil.

[0094] In embodiments, the planar flow cast metallic foils may have minimised variation in foil thickness and properties.

[0095] The planar flow cast metallic foil can be advantageously produced with a width and / or length that could not be previously produced by conventional planar flow cast methods. In embodiments, the planar flow cast metallic foil has a width of at least 10 mm, preferably at least 20 mm, more preferably at least 30 mm. In some embodiments, the planar flow cast metallic foil may have a width of at least 75 mm, preferably at least 100 mm, more preferably at least 250 mm. In some embodiments, the planar flow cast metallic foil may have a width of at least 300 mm. In embodiments, the planar flow cast metallic foil has a length of at least 300 mm, preferably a length of at least 500 mm, and more preferably a length of at least 1000 mm. It should be appreciated that the length may have any suitable length depending on the rolling capability of the planar flow casting apparatus / arrangement, and may in some cases be 1 m, 5 m or 10 m, or more in length. In embodiments, the planar flow cast metallic foil has a length of from 1000 to 3000 mm. In embodiments, e.g. steel and non-ferrous alloys, the metallic foil may be produced with a thickness of less than 1.5 mm. In embodiments, the metallic foil has a thickness of from 10 to 200 pm, preferably 20 to 150 pm. In other embodiments, for example amorphous metal or alloy foils (e.g. amorphous steel), the metallic foil may be produced with a thickness of less than 5 mm, for example from 1 to 5 mm. In alternate embodiments, for example amorphous metal or alloy foils (e.g. amorphous steel), the metallic foil may be produced with a thickness of less than 0.5 mm, for example from 0.01 to 0.5 mm, preferably less than 0.03 mm.

[0096] In examples, the disclosed planar flow cast metallic foil may comprise: a width of at least 75 mm; and a length of at least 1000 mm. In other examples, the disclosed planar flow cast metallic foil may comprise: a width of at least 100 mm; and a length of at least 1000 mm. As above, the planar flow cast metallic foil may be produced with a thickness of less than 1 .5 mm or 5 mm depending on the foil composition. In embodiments, the planar flow cast metallic foil may have a thickness of from 10 to 200 pm, preferably 20 to 150 pm. In other embodiments, for example amorphous metal or alloy foils (e.g. amorphous steel), the metallic foil may be produced with a thickness of less than 5 mm, for example from 1 to 5 mm. In alternate embodiments, for example amorphous metal or alloy foils (e.g. amorphous steel), the metallic foil may be produced with a thickness of than 0.5mm, for example from 0.01 to 0.5 mm, preferably less than 0.03 mm. In some embodiments, the planar flow cast metallic foil may have a width of at least 250 mm, or in other embodiments of at least 300 mm. Again, it should be appreciated that the length may have any suitable length depending on the rolling capability of the planar flow casting apparatus / arrangement, and may in some cases be 1 m, 5 m, 10 m, or more in length.

[0097] In embodiments, the planar flow cast metallic foil comprises a shape memory alloy foil, for example a Nickel-Titanium (NiTi) shape memory alloy foil. These have the advantages and applications noted above for the fourth aspect.

[0098] A sixth aspect provides a planar flow casting melt-delivery arrangement configured for the production of metallic foils from a metallic material, the meltdelivery arrangement comprising a high temperature receptacle that includes: at least one chamber configured to hold a metallic melt therein; a nozzle having at least one nozzle aperture configured for the egress of the metallic melt from the at least one chamber for foil formation; and at least one filter located within the at least one chamber, each filter configured to remove impurities from the metallic melt flowing therethrough.

[0099] It should be appreciated that this sixth aspect can take all the features described above for the first and second aspects.

[0100] A seventh aspect provides a planar flow casting melt-delivery arrangement configured for the production of metallic foils from a metallic material, the meltdelivery arrangement comprising a high temperature receptacle having a longitudinal axis extending therethrough, the high temperature receptacle comprising at least two chambers separated by at least one filter, said at least two chambers including: a melt chamber comprising a fluid holding space configured to hold a metallic melt therein; and a distribution chamber located axially below the melt chamber relative to the longitudinal axis, which includes a fluid holding space configured to hold a metallic melt therein, and a base that includes a nozzle having at least one nozzleaperture configured for the egress of metallic melt from the distribution chamber for foil formation, wherein the at least one filter is located between the melt chamber and the distribution chamber, each filter configured to remove impurities from the metallic melt flowing therethrough.

[0101] It should be appreciated that this seventh aspect can take all the features described above for the first and second aspects.

[0102] An eighth aspect provides a planar flow casting method of forming a metallic foil comprising: forming a metallic melt of a metallic material within a high temperature receptable; passing the metallic melt through at least one filter located within the high temperature receptable to remove impurities from the metallic melt flowing therethrough, to produce a filtered metallic melt; and feeding the filtered metallic melt through at least one nozzle aperture of the high temperature receptable for foil formation on a foil formation surface.

[0103] It should be appreciated that this eighth aspect can take all the features described above for the first, second, and third aspects.

[0104] The metal foils produced by the disclosed melt-delivery arrangement and associated planar flow casting method and system finds advantageous application as semi-finish feed materials in one or more of the following nonlimiting areas:(A) Aerospace and Defence (e.g. Ti alloys):• Aero structures.• Self-deploying mechanisms for solar panels, antenna, sensors system, or the like.• Robots.• lens shutter, shielding.(B) Biomedical devices and implants:• Miniaturised sensors and actuators.• Implants and drug delivery systems.• Anti-dust (e.g. amorphous metals and alloy foils)• Surgical tools.(C) Energy (e.g. steels, Ni, V, or the like based alloys):• Hydrogen separation membranes.• Solar panel.• Battery separators.• Fuel cell.• Electrodes.(D) Industrial processes:• Irradiation equipment.• Reactor vessels.• Sterilization of packaging.BRIEF DESCRIPTION OF THE DRAWINGS

[0105] Examples of the present invention will now be described with reference to the figures of the accompanying drawings, which, with the exception of Figure 1, wherein:

[0106] Figure 1 illustrates a schematic representation of a conventional (prior art) planar flow casting arrangement.

[0107] Figure 2 illustrates the forces and dimensions that control the formation of a foil from the melt that is dispensed through a melt-delivery nozzle in a planar flow casting arrangement - both conventional (prior art) and in accordance with embodiments of the present invention.

[0108] Figure 3 provides a front cross-sectional view of a melt-delivery arrangement according to one embodiment of the present invention having a single filter that may function as both a filter and a flow distributor.

[0109] Figure 3A provides a front cross-sectional view of a melt-delivery arrangement according to second embodiment of the present invention having two filters.

[0110] Figure 4 provides a photograph of a melt-delivery arrangement according to third embodiment of the present invention.

[0111] Figure 5 illustrates a schematic representation of a planar flow casting arrangement according to one embodiment of the present invention including a melt-delivery arrangement as shown in Figure 3.

[0112] Figure 6 provides a photograph of a planar flow casting arrangement according to one embodiment of the present invention.

[0113] Figure 7 provides a photograph of foils of NiTi alloy formed using a planar flow casting arrangement according to one embodiment of the present invention.

[0114] Figure 8 provides a front cross-sectional view of three examples of a meltdelivery arrangement according to embodiments of the present invention having a filter and a separate flow distributor, configured to produce foils having (a) 30 mm width; (b) 30 to 100 mm width; and (c) 100 to 300 mm width.

[0115] Figure 8A provides side cross-sectional views of the melt-delivery arrangements shown in Figure 8 that have a filter and a separate flow distributor, configured to produce foils having (a) 30 mm width; (b) 30 to 100 mm width; and (c) 100 to 300 mm width.

[0116] Figure 9 provides photographic images of sections of an example embodiment of the 30 mm foil width melt-delivery arrangement shown in Figure 8(a) showing (a) a front cross-sectional view similar to Figure 8(a); (b) the outercrucible configuration; (c) the filter configuration; (d) the nozzle aperture from within the distribution chamber; and (e) the flow distributor configuration.DETAILED DESCRIPTION

[0117] A new melting and melt-delivery system for scalable precision-production of metallic foils, preferably defect-free large-width metallic foils, by planar flow casting is disclosed.Planar Flow Casting

[0118] Planar flow casting (PFC) is a rapid solidification process which can produce thin metallic alloy foils and other planar products by ejecting metallic melt through a nozzle and quenching the melt into solid thin foils on the surface of a deposition surface, typically a chilled surface. The schematic of a conventional (prior art) planar flow casting system 100 for forming metallic foils is provided in Figure 1. This planar flow casting system 100 comprises:(A) a movable chill surface 105 formed on the outer surface of casting wheel 110; and(B) a melt-delivery arrangement 120 comprising a slotted nozzle 122 in communication with a high temperature receptacle 124 comprising a crucible holding metallic melt 125 in a reservoir 126, and a pressure means (not shown) for pressurizing the metallic melt 125 therein by gas over-pressure, head pressure of metallic melt or the like for causing egress of the metallic melt 125 from the reservoir 126 through the slot 127 in nozzle 122 onto the moving chill surface 105. Metallic melt in reservoir 126 is heated by a heating means, shown in Figure 1 as an electrical induction heating coil 128 which extends around the high temperature receptacle 124. Figure 1 illustrates that the high temperature receptacle 124 and nozzle 122 form a unitary (single) metallic melt distribution chamber.

[0119] Referring now to Figure 2, a foil is formed on chill surface 105, by locating the slotted nozzle 122 in close proximity to the chill surface 105, with the slot 127 oriented perpendicular to the direction of movement of the chill surface of the casting wheel 110. The slot 127 typically has a width B of about 0.2 to 1 mm, measured in the direction of movement of the chill surface (arrow W in Figures 1and 2). The length of the slot (not illustrated) determines the width of the strip, sheet or foil being cast. The gap G between the slot 127 and the chill surface 105 is at least about 0.1 times the width B of the slot 127, but may be large enough to equal the width B of the slot, depending on the thickness of the strip, sheet or foil being cast.

[0120] The casting wheel 110 typically comprises an annular wheel rotatably mounted on its longitudinal axis. However, it should be appreciated that other forms are possible, for example a belt arrangement or the like. The chill surface 105 may be formed from any metal or similar material having relatively high thermal conductivity, such as copper. Preferred materials of construction include beryllium copper and oxygen-free copper. If desired, the chill surface 105 may be highly polished or may be provided with a highly uniform surface, such as chrome plate, to enhance the bottom surface smoothness of the ribbon. To provide protection against erosion, corrosion or thermal fatigue, the chill surface 105 may be coated with a suitable resistant or high-melting coating. For example, a ceramic coating or a coating of corrosion-resistant high-melting metal may be applied by known procedures, provided that in each case the wettability of the metallic melt on the chill surface 105 is adequate.

[0121] In operation, metallic melt 125 in reservoir 126 is heated to at least the melting temperature of that metal in the single chamber melt-delivery arrangement 120. Once molten, the metallic melt 125 from the reservoir 126 is pressurized (equating to overpressure AP) to force it through the slot 127 of width (breadth) B in the nozzle 122. The nozzle 122 is held a gap G above the chill surface 105 of the casting wheel 110. An overpressure AP used to feed the metallic melt 125 through the slot 127 in nozzle 122 comprises the static head of the metallic melt 125 in the high temperature receptacle 124 and an applied gas pressure onto the metallic melt 124 that is preferably controlled to be constant as liquid is fed through nozzle 122. The flow is restricted in the gap G, and the metallic melt 125 forms a puddle of metallic melt 125A having a length L which is held by surface tension when it comes into contact with the chill surface 105. With sufficient contact between the chill surface 105 and molten puddle 125A, heat is removed from the metallic melt 125 and solidification occurs. This solidificationfront moves at an average velocity, V. The puddle 125 extends a short distance upstream, forming a meniscus extending between the chill surface 105 and the first edge 138 of the nozzle. Rotation of the casting wheel 100 extends the puddle 125 into a strip which solidifies as a metallic sheet, strip or foil 130 on the chill surface 105, as shown in Figure 1. The final cast thickness, T, of the sheet, strip or foil 130 is primarily controlled by the parameters B, G, AP and II. The casting wheel 110 moving with linear velocity, II, continually removes the solidified product from the metal deposition zone between the casting wheel 110 and nozzle 12. The formed solid sheet, strip or foil 130 can then be separated from the chill surface 105 (as shown in Figure 1).

[0122] As best shown in Figures 3 and 4, the planar flow casting arrangement of the present invention 200 follows a generally similar configuration as the conventional planar flow casting arrangement 100 illustrated in Figure 1 , generally comprising:(A) a movable chill surface 105 formed on the outer surface of casting wheel 210; and(B) a melt-delivery arrangement 220 comprising a slotted nozzle 222.However, compared to conventional arrangements (for example as shown in Figure 1), the planar flow casting arrangement illustrated in Figures 3 and 4 includes a new advantageous new melt-delivery arrangement 220 configuration which includes at least one filter 246 for filtering impurities such as oxide film, skin and / or inclusions from the metallic melt prior to casting the product metallic film. The new melting and melt-delivery arrangement 220 can be advantageously utilised to assist in producing defect-free (i.e. foils which do not have defects such as pinhole defects or similar) large-width metallic foils by planar flow casting.

[0123] Figures 3 and 4 illustrate examples of two embodiments of the meltdelivery arrangement 220 that include a single filter 246 therein. The illustrated melt-delivery arrangement 220 comprises a high temperature receptacle 124 comprising a crucible formed from a high temperature material, typically a carbonaceous material, such as graphite (see below). The crucible is divided into an upper chamber, comprising the melt chamber 240 which provides a fluid (metallic melt) holding space configured to hold and form a metallic melt of ametallic material therein; and the distribution chamber 242 which is located in this embodiment axially below the melt chamber 240 relative to a longitudinal axis L. The distribution chamber 242 also forms a fluid (metallic melt) holding space which can receive the metallic melt from the melt chamber 240. The distribution chamber 242 has a base that includes a nozzle 222 having at least one nozzle aperture 227 configured for the egress of metallic melt for foil formation. As best shown in Figure 4, that nozzle aperture 227 comprises elongate slot. That elongate slot typically has a width from 0.1 to 1.2 mm, preferably from 0.2 to 1.2 mm, more preferably from 0.2 to 1.0 mm. In some embodiments, the elongate slot typically has a width from 0.4 to 1.2 mm, and preferably from 0.5 to 1.0 mm. Similarly, the elongate slot typically has a length of 15 to 40 mm, preferably from 20 to 30 mm, particularly for Ti-based alloys. In other embodiments, the length of the nozzle aperture may be from 100 to 500 mm, preferably 200 to 300 mm, particularly for amorphous ferrous based alloys, such as amorphous steel. However, it should be appreciated that width and / or length of the nozzle aperture may be configured to correspond with the desired width of the metallic film that is being planar flow cast.

[0124] In some embodiments, the nozzle 222 may have a wide width (e.g. 0.5 to 1.2 mm). In these embodiments, the base or bottom plate of the nozzle 222 may be configured to have an equiangular shape. The distance of the aperture to the four side surfaces can be controlled.

[0125] In particular examples, for instance Ti alloy foils, the nozzle aperture 227 may comprises an elongate slot that typically has a width from 0.4 to 1.2 mm, and preferably from 0.5 to 1.0 mm, for example around 0.5 mm. For forming amorphous steel of a specific thickness such as 20 to 25 urn, nozzle aperture 227 may comprises an elongate slot that typically has a width of 0.1 to 0.6 mm, for example 0.2 to 0.5 mm, or around 0.2 mm in some forms. For example, for amorphous steel foils, the operation conditions in some embodiments may comprise an nozzle aperture 227 having a width of 0.25 mm for 25 to 30 pm thickness, (other parameters for this set up may comprise 1600 rpm, of 296 mm diameter wheel, melting temperature 1100 °C, ejection pressure 0.1 bar, and 0.7 mm gap between wheel and nozzle (rubbing)).

[0126] The melt chamber 240 and the distribution chamber 242 in the embodiments shown in Figures 3 and 4 (and not Figure 3A) are separated by a single filter 246. The filter 246 in this embodiment functions as an impurity filter (as described below) and also as a flow distributor for the metallic melt. The filter 246 comprises a plate or sheet, formed from a high temperature material, such as ceramic, or a ceramic coated plate, which in this embodiment functions both as a flow distributor and filter for the metallic metal that flows between the melt chamber 240 and distribution chamber 242. This flow distribution and impurity filter function is provided by the inclusion of one of more fluid flow apertures 250 in the body of the filter 246. The fluid flow apertures 250 are configured to allow a selected fluid flow of metallic melt to flow therethrough in a desired flow distribution (equating to the spacing and configuration of the fluid flow apertures 250 in the filter 246) from the melt chamber 240 to the distribution chamber 242. The size and the number of the apertures 250 in the filter 246 can be designed to maximise flow rate of the metallic melt filling the distribution chamber 242 (reducing time of heat loss) while ensuring retention of filtride. The locations of the apertures 250 are preferably configured to deliver the incoming metallic melt uniformly into the distribution chamber 242 - as will be discussed in more detail below. The impurity filtering function enables melt-delivery arrangement 220 to remove films and / or inclusions of oxide impurities from the molten high- temperature nonferrous alloy, preventing this oxide material from blocking the nozzle aperture 227 and from forming oxidation defects (e.g., pinholes) in the formed foil.

[0127] The filter 246 in the illustrated embodiment is seated on an annular seat 245 formed in the sidewall of the high temperature receptable 224. This arrangement may allow removal of the filter top-wise through the melt chamber 240 without full disassembly of the high temperature receptacle 124. This can also enable the high temperature receptacle 124 to be configured with removable / replaceable filters for different applications, for example using filters configured for different metals or metal alloys. However, it should be appreciated that the filter can be included in the high temperature receptable 224 in other manners and arrangements.

[0128] It should be appreciated that the two chambers of this embodiment merges a melting crucible (melt chamber 240) and a traditional separate nozzle (distribution chamber 242) into a single receptacle that is separated by the filter 246. This arrangement enables a two-step - melting and melt-delivery - process to be conducted in a single melt-delivery arrangement 220. Here, the melt chamber 240 is configured to allow the metal or alloy to melt and become molten when heated in that chamber above the melting point. The distribution chamber 242 functions to deliver and substantially evenly distribute the filtered molten material through the nozzle aperture 227 (an elongate slot) onto a foil formation surface to form the metallic foil.

[0129] The melt delivery arrangement 220 can include two or more filters 246 in some embodiments. Figure 3A illustrates one melt delivery arrangement 220A that includes two spaced apart filters 246A and 246B, separated by a filter space 247A. This filter space 247A can have any suitable volume, but typically is not used as a metallic melt holding space, but rather forms a space where unwanted inclusions and other impurities are captured and held whilst the metallic melt flows between the melt chamber 240A to the distribution chamber 242A. However, it should be appreciated that in some embodiments, this filter space 247A can have any suitable volume, may be used as a metallic melt holding space. In some embodiments, that filter space 247A may define an intermediate chamber, which may be temperature controlled. As shown in Figure 3A, each filter 246A and 246B are designed with different sized apertures 250A and 250B, with the upper filter 246A having larger apertures 250A compared to the apertures 250B of the lower filter 246B. The upper filter 246A will therefore remove impurities and inclusions from the metallic melt of a certain size. The lower filter 246B (or filters if there are more than two) have apertures 250B that are sized to remove any smaller impurities and / or inclusions from the metallic melt that may have passed through the upper filter 246B. This melt delivery arrangement 220A otherwise functions the same as described for the melt delivery arrangement 220 shown and described in relation to Figures 3, 4 and 5. It should be understood that like features have been provided the same reference numerals as shown and described in relation to Figure 3 plus 0A.

[0130] The high temperature receptacle 224 is typically a generally cylindrical crucible formed from a carbonaceous based material such as graphite, or from aluminium oxide, preferably including an inner coating or lining of an inert refractory material (see below). Although, it should be appreciated that other materials are possible such as AIN; shock resistant refractory metals such as Ta, W, Mo coated with inert materials (such as Y2O3); or ceramic composites like BaZrOs and CaO-doped BaZrOs. It should also be appreciated that other shapes and / or configurations could equally be used. The interior surfaces 255A and 255B of the melt chamber 240 and distribution chamber 242 can also include an optional inner high temperature ceramic layer, lining or material selected to have low wetting properties to the metallic melt, and to minimise the reaction between the molten metals and the containment materials. Suitable examples of a ceramic coating, layer or lining comprises at least one high temperature ceramic, preferably selected from at least one of: aluminium oxide (AI2O3), quartz, boron nitride (BN), or yttrium oxide (Y2O3), AINi or, a refractory oxide. In exemplary embodiments, this ceramic coating, layer or lining comprises at least one boron nitride (BN) layer and at least one layer of yttrium oxide (Y2O3), and more preferably at least two boron nitride (BN) layers and at least one layer of yttrium oxide (Y2O3).

[0131] The ceramic coating or layers formed in the internal surfaces 255A and 255B of the melt chamber 240 to the distribution chamber 242 can be included in a variety of ways. In some embodiments, layers or sheets of ceramic can be included in the appropriate sections or surfaces 255A and 255B of the melt chamber 240 and the distribution chamber 242 in the high temperature receptacle 224. For example, as illustrated in the embodiments shown in Figures 3, 3A and 4, a purpose-built ceramic insert 257, for example a boron nitride insert, is fitted into an outer / base graphite crucible 258 to form the overall structure of the high temperature receptacle 220. In other embodiments, a ceramic coating or lining can be applied to the appropriate sections or surfaces 255A and 255B of the melt chamber 240 and the distribution chamber 242 in the high temperature receptacle 224.

[0132] One example of applying a ceramic coating to the appropriate internals surfaces 255A and 255B of the melt chamber 240 and the distribution chamber 242 is where these internal surfaces 255A and 255B are coated (e.g., brush coated) with two boron nitride (BN) layers of total 0.3 to 0.4 mm thickness, followed by a coating (e.g., spray coating) of yttrium oxides (Y2O3). Each of these coating layers are dried at 90 °C after application, and before applying the subsequent coating. The advantage of using one or both of these coatings is to prevent the molten metals containing Ti reacting with the underlying graphite used in the high temperature receptacle 220, which could result in the formation of pinhole defects in the formed foils, or nozzle 222 blockage.

[0133] The bottom or base 264 of the distribution chamber 242 is preferably designed to have lower heat capacity relative to the sidewalls of the distribution chamber 242 and / or the sidewalls of the high temperature receptacle 124. Practically, this can be embodied in the high temperature receptacle 124 by designing the bottom or base 264 of the distribution chamber 242 to be thinner the sidewalls of the high temperature receptacle 124. For example, the bottom or base 264 of the distribution chamber 242 could be designed to be only 1 mm thick, to mitigate any excessive heat sink properties from the metallic melt that would otherwise occur with a thicker base. However, it should be appreciated that this could also be achieved using other means, such as different materials with selected thermal performance.

[0134] As shown in Figure 5, the melt-delivery system 200 is located within a heating arrangement 228, in this case an inductive heating coil unit, configured to heat the metallic material within the high temperature receptacle, and more particularly the melt chamber 240 and / or the distribution chamber 242 to at least the melting point of that metallic material. Again, it should be appreciated that any suitable heating arrangement or system could be used. As shown in Figure 5, the heating arrangement 228 comprises an induction coil unit that is configured to extend over the melt chamber 240 to the distribution chamber 242, extending to the nozzle 222 of the distribution chamber 242. The length of the nozzle 222 and the induction coil of heating arrangement 228 are preferably designed in suchway that the distribution chamber 242 and the nozzle 222 thereof can be inside the hot zone of the coil, so it can be sufficiently pre-heated while being empty.

[0135] The heating arrangement 228 can be configured to heat the metallic material within the melt chamber 240 and the distribution chamber 242 to at least the melting point of that metallic material. In some embodiments, the heating arrangement 228 is configured to heat both the melt chamber 240 and the distribution chamber 242. However, in other embodiments, the heating arrangement 228 can be configured to independently heat the melt chamber 240 and the distribution chamber 242, for example using two separately controlled heating units.

[0136] The melt-delivery system 220 is housed within an atmosphere-controlled chamber 260 which is configured to flush and / or fill the high temperature receptacle with an inert gas atmosphere, such as nitrogen, argon, or neon. In many forms the atmosphere-controlled chamber 260 is a vacuum chamber. The atmosphere-controlled chamber 260 is configured to substantially extract the gaseous atmosphere within the high temperature receptacle, and backfill with an inert gas atmosphere. The aim is to reduce the oxygen content in the chamber to 50 ppm or less, and preferably 30 ppm or less and introduce an inert gas atmosphere within the high temperature receptacle 220 at a pressure of at least 0.3 bar, preferably at least 0.5 bar. The atmosphere-controlled chamber 220 is also used to produce an overpressure AP used to feed the metallic melt from the distribution chamber 242 through the nozzle aperture 227 in nozzle 222.

[0137] It should be appreciated that a suitable a control system and / or control method could be used for control various parameters of the system including of the heating arrangement 228, and the atmospheric pressure and inert gas flow within the atmosphere-controlled chamber 260, including the produced overpressure AP.Non-Converging Nozzles

[0138] The planar flow casting melt-delivery arrangement may be configured to control melt flows within the nozzle. Figures 8 (front cross-sectional view) and 8A (side cross-sectional view) provides three examples of a melt delivery system320, 320A, 320B that include a flow distributor 349, 349A1, 349A2, 349B1, 349B2, 349B3 that functions to redistribute the melt from the melt chamber 340, 340A, 340B to and through the distribution chamber 342, 342A, 342B so that the metallic melt flows across (preferably in a uniform flow across) the whole length of the nozzle aperture 327, 327A, 327B.

[0139] It should be appreciated that the melt delivery system 320, 320A, 320B illustrated in Figure 8 and 8A have similar features and function to the melt delivery system 220 illustrated and described in relation to Figures 3 to 5, and that the description of like features of that embodiment equally applies to these embodiment. In this regard, like features of the melt delivery system 320, 320A, 320B have been given the same reference numeral as the features of the melt delivery system 220 (Figures 3 to 5) PLUS 100, 100A and 100B respectively.

[0140] Referring to firstly to the melt delivery system 320 illustrated in Figures 8(A) (front view) and 8A(A) (side view). This melt delivery system 320 has been configured to produce metallic foils having a width of around 30 mm. The melt delivery system 320 and high temperature receptacle (crucible) 324 have a similar configuration as described for the melt delivery system 220, with the addition of a flow distributor 349 between the filter 346 and the nozzle aperture 327, which is located within the distribution chamber 342, spaced apart from the nozzle aperture 327. The flow distributor 349 may be configured to re-distribute the metallic melt flows and minimise their non-uniformity and variation.

[0141] This flow distributor 349 may be configured to control the flow related to the foil width, by distributing the metallic melt (and thus providing control of the metallic melt) so that it flows across (preferably in a uniform flow across) the whole length of the nozzle aperture 327. This control may be utilised to deliver a selected (and controlled) flow rate and temperature of the melt at the nozzle aperture 327 that may be designed to form quality thin foils, thereby minimising the inconsistency of thickness and properties of the produced foil.

[0142] As best shown in Figure 8A(A), the high temperature receptacle (crucible) 324 has a cylindrical shape, and is divided into a melt chamber 340, comprising a cylindrical chamber containing a filter 346 configured and functioning asprevious described for the melt delivery system 220 illustrated in Figures 3 to 5. The distribution chamber 342 is formed in two parts in this embodiment, separated by the flow distributor 349. The upper section 351 above the flow distributor 349 comprises a cylindrical chamber. The lower section 353 below the flow distributor 349 (on the nozzle aperture 327 side) comprises an extended nozzle which provides a substantially rectangular shaped chamber spaced around and leading to at the base the elongate (slot) nozzle aperture 327. In this embodiment, the transition from the circular cross-section upper section 351 to the rectangular cross-section lower section 353 (nozzle 322) is a sharp transition separated by the flow distributor 349. The lower section 353 may be designed as a flow distributor / funnel, to direct the metallic melt flow from the flow distributor 349 into a smaller volume chamber which essentially funnels or otherwise directs the melt in this elongate shaped space towards the elongate (slot) nozzle aperture 327.

[0143] In the embodiment illustrated in Figure 8(A), the front width W1 (inner dimension) of the melt chamber 340 is similar to the front width W2 (inner dimension) of the two sections (upper section 351 and lower section 352) of the distribution chamber 342 and the width of the nozzle 322. However, as shown in Figure 8A(A), the side dimensions show that this lower section 352 (nozzle 322) of the distribution chamber 342 has a significantly narrower dimension W4 compared to the width W1 of the melt chamber 340.

[0144] In other embodiments, for example as shown in Figures 8(A), 8(A), the front width W1 of the melt chamber 340A, 340B may have a narrower dimension, for example width, compared to the front width W2 of the lower section 352B of the distribution chamber 342A, 342B and the nozzle 222A, 222B at the base of that distribution chamber 342A, 342B. In such embodiments, it may be advantageous to control melt flows through the distribution chamber 342A, 342B and nozzle 322A, 322B to assist a uniform flow to be distributed across the width the distribution chamber 342A, 342B. This then may be used to minimise non- uniform metallic flows when the metallic melt exits the nozzle aperture 327A, 327B.

[0145] Figures 8(B) (front view) and 8A(B) (side view) illustrates one example of a melt delivery system 320A configured to produce 30 to 100 mm wide foils. As shown in Figure 8(B) the front width W2 of the distribution chamber 342A (and the nozzle aperture 327A therein) is greater than the front width W1 (inner dimension) of the melt chamber 340A. However, as shown in Figure 8A(B), the side dimensions show that this lower section 352A (nozzle 322A) of the distribution chamber 342A has a significantly narrower dimension W4 (inner dimension) compared to the width W1 of the melt chamber 340A.

[0146] In this embodiment, the lower section 352A (nozzle 322A) of the distribution chamber 342A may be configured to distribute the metallic flow outwardly from the axis X along the wider width W2 of this lower section 352A. To assist in this transition, the lower section 352A (nozzle 322A) of the distribution chamber 342A may include a sloped transition surface 343A (forming a sloped transition zone within the distribution chamber 342A) when transitioning from width W1 (inner dimension) of the melt chamber 340A to the width W2 (inner dimension) of the distribution chamber 342A. Each flow distributor 349A1 and 349A2 may assist in distributing a flow laterally relative to the axis X, such that a uniform flow may be distributed across the width the distribution chamber 342A following that increase in width / cross-sectional area of the distribution chamber 342A. As the melt progressively axially downwardly, this may assist in distributing the metallic melt (and thus providing control of the metallic melt) through that entire extended width so that it flows across (preferably in a uniform flow across) the whole length of the nozzle aperture 327A.

[0147] Similar to the embodiment illustrated in Figure 8A and 8A(A), the lower section 353A below the flow distributor 349A (on the nozzle aperture 327A side) may comprise an extended nozzle which provides a substantially rectangular shaped chamber spaced around and leading to at the base the elongate (slot) nozzle aperture 327A. The narrowing of dimension to width W4 (inner dimension) may funnel the metallic melt flow through this elongate shaped space towards the elongate (slot) nozzle aperture 327A, and may assist melt flow to be distributed outwardly from axis X along the front expanded width dimension W2 (inner dimension).

[0148] Figures 8(C) (front view) and 8A(C) (side view) illustrates an example of a melt delivery system 320A configured to produce 100 mm to 300 mm wide foils. In this embodiment, the lower section 352B (nozzle 322B) of the distribution chamber 342B has a tiered structure comprising two tiered sections 365A and 364B which provide a progressively larger width size W2 (inner dimension) and W3 (inner dimension) from the melt chamber 340B to the nozzle aperture 327B. Like the previous embodiment, the front widths W2 and W3 (inner dimension) of the lower section 352B of the distribution chamber 342B is greater than the front width W1 (inner dimension) of the melt chamber 340B. Again, as shown in Figure 8A(C), the side dimensions shows that this lower section 352B (nozzle 322B) of the distribution chamber 342B has a significantly narrower dimension W4 (inner dimension) compared to the width W1 of the melt chamber 340B.

[0149] In this embodiment, the lower section 352B of the distribution chamber 342B may be configured to progressively distribute the metallic flow outwardly from the axis X along the wider widths W2 and W3 of each tier 365A and 365B of this lower section 352A. To assist in this transition, each tiered section 365A and 365B may include a sloped transition surface 343B and 343C (forming a sloped transition zone within the distribution chamber 342B) when transitioning from width W1 (inner dimension) of the melt chamber 340A to the width W2 (inner dimension) and from width W2 (inner dimension) to width W3 (inner dimension) respectively of the distribution chamber 342A.

[0150] The distribution chamber 342B of this embodiment includes three flow distributors 343B1 , 343B2 and 343B3 - two positioned at the width transition positions (343B1 and 343B2) and one located at a position axially above the aperture 327B. Whilst each tiered section 365A and 365B includes an initial flow distributor 349B1 and 349B2, it should be appreciated that each tiered section 365A and 365B may include more than one flow distributor where desired and / or appropriate. In this configuration, each flow distributor may be configured to control and distribute melt flows through that tiered section of the distribution chamber, to assist a uniform flow to be distributed across the expanded width of that tiered 343A and 343B of the distribution chamber 342B. Each flow distributor 349B1 , 349B2 and 349B3 may assist in distributing a flow laterally relative to theaxis X, such that a uniform flow may be distributed across the width the distribution chamber 342B following that increase in width / cross-sectional area of the distribution chamber 342B. Flow distributor 343B3 may be included as a final control to distribute the metallic melt so that it flows across (preferably in a uniform flow across) the whole length of the nozzle aperture 327B. Again, this may be used minimise non-uniform metallic flows when the metallic melt exits the nozzle aperture 327B.

[0151] Similar to the embodiment illustrated in Figure 8A and 8A(A), the lower section 353B below the flow distributor 349B (on the nozzle aperture 327B side) may comprise an extended nozzle which provides a substantially rectangular shaped chamber spaced around and leading to at the base the elongate (slot) nozzle aperture 327B (best illustrated in Figure 8A(C)). The narrowing of dimension to width W4 (inner dimension) may funnel the metallic melt flow through this elongate shaped space towards the elongate (slot) nozzle aperture 327B, and assists melt flow to be distributed outwardly from axis X along the front expanded width dimension W2 (inner dimension).

[0152] For all of the above embodiments, the flow distributor 349, 349A1 , 349A2, 349B1 , 349B2, 349B3 may have various configurations which are permeable to the metallic melt but filter selected materials from the molten material. In embodiments, the flow distributor 349, 349A1 , 349A2, 349B1 , 349B2, 349B3 may comprise a separator body that facilitates fluid flow through the filter via at least one pore, aperture, permeable structure, or the like. In some embodiments, each flow distributor 349, 349A1 , 349A2, 349B1 , 349B2, 349B3 may comprise a separator body, for example a solid body, such as a plate or sheet (e.g. a ceramic plate, or a ceramic coated plate), that includes at least one aperture, preferably a plurality of apertures. Nevertheless, it should be appreciated that other flow distributor embodiments may be possible, for example a strainer or sieve configuration, or high temperature materials that have a selected permeability and / or porosity.

[0153] The apertures in the flow distributor 349, 349A1 , 349A2, 349B1 , 349B2, 349B3may comprise through-apertures or through-holes that form a fluidpassage through the flow distributor 349, 349A1 , 349A2, 349B1 , 349B2, 349B3. The apertures may have any suitable configuration for example, slots, circular, oval, square, rectangular or other polygonal shapes, preferably regular polygonal shapes. In some embodiments, the apertures in the flow distributor 349, 349A1 , 349A2, 349B1 , 349B2, 349B3may comprise circular through-holes. The apertures may play an important role in determining flow and thermal distribution of the metallic melt when passing therethrough. In embodiments, at least one of the size, location and number of apertures in the flow distributor 349, 349A1 , 349A2, 349B1 , 349B2, 349B3are configured to provide a substantially uniform flow of metallic melt when metallic melt flows through each aperture.

[0154] A uniform flow distribution of metallic melt through the flow distributor 349, 349A1 , 349A2, 349B1 , 349B2, 349B3may be facilitated by configuring the flow distributor with apertures that are substantially evenly distributed across the planar area perpendicular to the longitudinal axis of each flow distributor 349, 349A1 , 349A2, 349B1 , 349B2, 349B3. In embodiments, the apertures may be substantially evenly distributed across the lateral or planar area that is perpendicular to the longitudinal axis of each flow 349, 349A1 , 349A2, 349B1 , 349B2, 349B3when the flow distributor 349, 349A1 , 349A2, 349B1 , 349B2, 349B3is located within the distribution chamber 342, 342A, 342B. In each case, the apertures may be configured to distribute the metallic melt so that it flows across (preferably in a uniform flow across) the whole length of the nozzle aperture 327, 327A, 327B.

[0155] One particular example of a flow distributor 349 is illustrated in Figure 9. Figure 9 provides photographic images of sections of an example embodiment of the 30 mm foil width melt-delivery arrangement shown in Figure 8(a) showing (a) a front cross-sectional view similar to Figure 8(a); (b) the outer crucible 324 configuration; (c) the filter 346 configuration; (d) the nozzle aperture 327 from within the distribution chamber 342; and (e) the flow distributor 349 configuration. As shown in Figure 9, the high temperature receptacle (crucible) 324 has a cylindrical shape, formed of materials as previously described, and is divided into a melt chamber 340, comprising a cylindrical chamber containing a filter 346 configured and functioning as previous described for the melt delivery system220 illustrated in Figures 3 to 5. As previously described, the distribution chamber 342 is formed in two parts in this embodiment, separated by the flow distributor 349. The upper section 351 above the flow distributor 349 comprises a cylindrical chamber having a slightly smaller width that the melt chamber 340. The lower section 353 comprises an elongate chamber, substantially rectangular shaped chamber spaced around and leading to at the base the elongate (slot) nozzle aperture. Melt flows into this lower section 353, through the flow distributor 349 into a smaller volume chamber which essentially funnels or otherwise directs the melt in this elongate shaped space towards the elongate (slot) nozzle aperture 327.

[0156] As best shown in Figure 9(e), the flow distributor 349 comprises a separator body, for example a ceramic plate or sheet, that includes apertures 359. In this example, the separator body includes five linearly aligned apertures 359. These apertures 359 may be configured to be aligned or otherwise positioned in a location on the separator body, and within the distribution chamber 342 that is favourably positioned relative to the alignment of the nozzle aperture 327 located in this case in the nozzle 322 positioned at the base of the lower section 353. In the illustrated example, this results in the apertures 359 being linearly aligned with the slot shaped nozzle aperture 327, so to distribute the metallic melt to flows across (preferably in a uniform flow across) the whole length of the nozzle aperture 327.

[0157] The melt delivery arrangement may not necessarily be limited to having a single flow distributor. The planar flow casting melt-delivery arrangement may have any number of flow distributors. In some embodiments, for example as shown in Figure 8(B) the planar flow casting melt-delivery arrangement / high temperature receptacle may include two flow distributors 349A1 and 349A2; or for example as shown in Figure 8(C) the planar flow casting melt-delivery arrangement / high temperature receptacle may include three flow distributors 349B1 , 349B2 and 349B3. In each embodiment shown in Figure 8(B) and Figure 8(C), multiple flow distributors (349A1 and 349A2 in Figure 8(B) and 349B1 , 349B2 and 349B3 in Figure 8(C)) are configured to assist in a progressive flow distribution where there is a large change in width or dimension from the meltchamber 340A and 340B to the nozzle aperture 227A and 227B. The use of two or more flow distributors may also allow these flow distributors to have different structures or configurations, such as different aperture sizes, different porosity, different permeability or the like.Planar Flow Casting Operation

[0158] In this example, the melt-delivery arrangement 220 is described as being utilised with a planar flow casting machine that includes a casting wheel 210 having a chill surface 205, a heating arrangement 228 (an induction heating unit), and an atmosphere-controlled chamber 260 which houses the melt-delivery arrangement 220 therein. Accordingly, operation of the planar flow casting system 200 generally follows the same overall operational steps as described for the conventional system 100 described above, with the exception of the new configuration of the melt-delivery arrangement 220. Operation of the illustrated planar flow casting system 200 is as follows:

[0159] Firstly, ingots of the metallic material, for example high-temperature nonferrous alloy, are placed in the melt chamber 240, and in this example on the top of the filter 246. The assembled melt-delivery arrangement 220 is positioned in the heating arrangement 228 (e.g., in the centre) - an induction heating unit having an induction coil - which is located inside the atmosphere-controlled chamber 260 (see Figure 5). In this particular example, the length of the high temperature receptacle 124 and the induction coil of the heating arrangement 228 are designed in such way that the distribution chamber 242 and the nozzle 222 can be inside the hot zone of the induction coil, so it can be sufficiently preheated while being empty.

[0160] With the completion of the melt-delivery arrangement 220 and heating arrangement 228, the atmosphere within the atmosphere-controlled chamber 260 is replaced with an inert gas, for example high purity argon, to reduce the oxygen content in the chamber to 50 ppm or less, and preferably 30 ppm or less and introduce an inert gas atmosphere within the melt-delivery arrangement 220. An excessive presence of oxygen in the atmosphere of the atmosphere-controlled chamber 260 will contribute to the increasing of the oxygen level in the moltenmetals, forming extremely brittle foils if up to 1000 to 2000 ppm. In some embodiments, this can involve three cycles of firstly vacuuming the chamber to 200 millitorr (2.66x1 O'4bar) and then back-filling of high purity argon (Ar) to 0.5 bar. Once the low oxygen level is achieved, the atmosphere-controlled chamber 260 is backfilled with high purity Ar to about 0.34 bar being ready to commence heating and melting of the ingots of the metallic material within the melt chamber 240.

[0161] The illustrated melt-delivery arrangement 220 enables a two-step - melting and melt delivery - process to be undertaken within a single high-temperature receptacle 224. Though it should be appreciated that other configurations of the high-temperature receptacle 224 in accordance with the invention could equally be used.

[0162] At the first step of the melting process, the alloy becomes molten in the melt chamber 240 when temperature increase above the melting point of the metallic material. During this phase, only a moderate heating power (e.g., 30% of the 130 kW power unit) is preferably used as faster heating could create hot spots in the alloy ingots leading to only partially melting alloy ingots. When the melt temperature is slightly above the alloy melting point, the metallic melt with a minimum overheat is allowed to flow through the apertures 250 in the filter 246 and into the distribution chamber 242. This is controlled by surface tension in the metallic melt across the aperture(s) 250 in the filter 246, which can be overcome by increasing the temperature of the metallic metal to a certain overheat temperature, and / or through the application of an overpressure (if needed). An overheat is desired to keep the alloy molten when flowing through the apertures 250 of the filter 246, and remain molten in the distribution chamber 242, and thus is related to alloy melting points and the size, number and distribution of the apertures 250 in filter 246.

[0163] When the desired overheat temperature is reached, the pressure head from the weight of metallic melt in combination with the molten fluid properties at that temperature overcomes the surface tension across the apertures 250 in the filter 246 allowing the metallic melt to flow through the apertures 250. In manycases, a 5 to 20 degree overheat is sufficient. Furthermore, 3 mm diameter apertures 250 have been found to be adequate to achieve a required superheat for the high-temperature alloys with a melting point between 1300 °C and 1800 °C.

[0164] While the oxygen level is low (typically 50 ppm or less as noted above) within atmosphere-controlled chamber 260, an oxide skin can still form that envelops the metallic melt in the melt chamber 240. The formation of the reduced oxide skin is desirable since it acts as the addition resistance to the reaction between the metallic melt and the internal surfaces of the melt chamber 260, the filter 246 and the distribution chamber 242. After the melt chamber 240 is empty of the molten metal, oxide skin and inclusions in the metallic melt are left behind on the top surface of the filter 246 in the melt chamber 240. As indicated above, the filter 246 separating the nozzle chambers advantageously acts as a filter removing the oxide films and / or inclusions from the molten metal, preventing these from blocking the nozzle aperture 227 and forming oxidation defects (e.g., pinholes) when the foil is formed on the chill surface 205 (Figure 5).

[0165] The completion of melt transference from the melt chamber 240 to the distribution chamber 242 through the apertures 250 of the filter 246 can be indicated by the absence of melt in the melt chamber 240. Due to the high temperature, this can be measured using a pyrometer or another suitable temperature sensor to measure a change in the melt temperature within the melt chamber 240. That change can be the measured temperature becoming flat or even decreasing. This signals the start of the second step of the melting process in the distribution chamber 242. As noted above a control system may be used in top control and operate the heating arrangement 228, and the atmospheric pressure and inert gas flow within the atmosphere-controlled chamber 260. That control system may also use the output from the pyrometer as a control parameter.

[0166] During this second melting step, one or more of the following three factors are used to assist in planar flow casting full-width foils:

[0167] Firstly, the loss of the melt heat in the distribution chamber 242 is minimised, in particular, around the nozzle aperture 227. Excessive heat loss at the nozzle 222, and in particular in the nozzle aperture 227 where the temperature is the lowest, would solidify the melt partially or fully blocking the nozzle aperture 227. In addition, the minimised heat loss in the distribution chamber permits the metallic melt in the melt chamber 240 to have a small superheat - and thus having a lower oxidation contamination. This minimization of the loss of the melt heat can be achieved by:1. Reducing heat sinking inside the distribution chamber 240 through the above described dual-chamber design of the melt-delivery arrangement 220. This design merges the conventional separate melting crucible and nozzle distribution arrangement, thereby eliminating of the additional heat sink mass of a separate nozzle.2. Optimally positioning the nozzle aperture 247 together with the distribution chamber 242 in the hot zone of the heating arrangement 228 (illustrated as an induction coil), thus being pre-heated uniformly to a higher temperature, and thus reducing less heat sinking between the melt chamber 420 and distribution chamber 242. It should be noted that this high-temperature pre-heating is possible without the risk that the metallic melt prematurely leaks from the nozzle aperture 227 because the alloy ingots are initially melted in the melt chamber 240 rather than in the distribution chamber 242 (which is fluidly linked to the nozzle 222).3. Designing the area and the number of the apertures 250 in the filter 246 to maximise flow rate of the metallic melt filling the distribution chamber fast (reducing time of heat loss), while ensuring retention of filtride.4. Designing the bottom or base 264 of the distribution chamber 242 to have a lower heat capacity to the remaining parts of the high temperature receptacle, for example being only 1mm thick, thus mitigating the possibility that a thick base may act as a heat sink absorbing heat from the molten metal.

[0168] Secondly, the metallic melt within the distribution chamber 242 can be restricted from flowing out from the nozzle aperture 227 before an ejection pressure is applied by configuring the nozzle aperture 227 to establish a static metallic melt over the whole width of the nozzle aperture 227. The static metallicmelt is formed over the width of the nozzle aperture 227 through combination of the nozzle aperture 227 dimensions and the temperature of the metallic melt within the distribution chamber 242 bearing on the required surface tension of the molten metal. This stationary metallic melt will allow a uniform egress of the metallic melt when ejected onto the chill surface 205 of the casting wheel 210, thus assisting in the rapid and uniform solidification of the metallic foil. The inventors have established that this control is possible by designing the nozzle aperture 227 as a slot having a width of 0.5 to 1.0 mm. The length of the slot is dependent on the width of film produced, but typically can be 10 mm to 40 mm, for example 30 mm.

[0169] Thirdly, the temperature distribution of the metallic melt within the distribution chamber is preferably substantially uniform to prevent cold spots around the nozzle aperture 227 in the bottom of the nozzle 222. The temperature distribution of the metallic melt is related to:(1) the incoming flows of the metallic melt through the apertures 250 in the filter 246; and(2) the time in which the stationary metallic melt is held in the distribution chamber 242 before being ejected onto the chill surface 205.

[0170] A uniform thermal distribution can be initially achieved within the distribution chamber 242 by designing the locations of the apertures 250 of the filter 246 to deliver the incoming metallic melt uniformly into the distribution chamber 242. The arrangement of the apertures 250 is configured in conjunction with the size of the apertures 250 as this combination affects heat sinking - as described above. For example, for a melt-delivery arrangement used to fabricating Ni-Ti shape memory alloy foil, the inventors have used a 30 mm diameter ceramic plate for the filter 246 that has 9 evenly distributed apertures 250 with an aperture size of from 3 mm to 5.5 mm.

[0171] Finally, the evolution of the melt temperature from the initial to the final distribution is influenced by the time the stationary metallic melt is held within the distribution chamber 242. Whilst the heating arrangement can be operated to maintain the melt temperature whilst the metallic melt is in the distributionchamber 242, there is an option to turn the heating on or off during this holding time. In embodiments, a short holding time (e.g. 5 to 10 seconds) can be used without the induction power is suitable for producing quality metallic foil, in particular Nickel-Titanium (Ni-Ti) shape memory alloys (SMAs). However, it should be appreciated that this step could equally be conducted with heating on if desired.

[0172] For those embodiments that include at least one flow distributor, for example as illustrated in Figures 8 and 9, the melt within the distribution chamber 342, 342A1 , 349A3, 342B passes through one or more flow distributors 349, 349A1 , 349A2, 349B1 , 349B2, 349B3 prior to passing through the nozzle aperture 327, 327A, 327B. As previously described, the flow distributors 349, 349A1 , 349A2, 349B1 , 349B2, 349B3 may be configured to control the flow in relation to the desired produced foil width, and may therefore be configured to distribute the metallic melt (and thus providing control of the metallic melt) so that it may flow across (preferably in a uniform flow across) the whole length of the nozzle aperture 327, 327A, 327B. In these embodiments, operation of the melt delivery arrangement further comprises passing the metallic melt through at least one flow distributor 349, 349A1 , 349A2, 349B1 , 349B2, 349B3 located within the high temperature receptable 324, 324A, 324B to redistribute the filtered metallic melt within the high temperature receptable so that it flows across (preferably in a uniform flow across) the whole length of the nozzle aperture 327, 327A, 327B.

[0173] Operation of the planar flow casting apparatus then follows the process as described above in relation to Figure 1. In this respect, like components in the planar flow casting system shown in Figure 5 have been provided the same reference numeral PLUS 100.

[0174] For foil formation, the nozzle assembly is lowered to the rotating casting wheel 210 during the short holding time (e.g. 5 to 10 seconds as above) the metallic melt is held in the distribution chamber 242, to a distance almost touching the chill surface 205 of the casting wheel 210 - typically about 0.1 to 1 mm, for example 0.7 mm. Once the nozzle 222 is positioned to provide this small gap, the argon pressure in the atmosphere-controlled chamber 260 (and thus within themelt chamber 240 and distribution chamber 242) is increased to the ejection pressure, comprising overpressure AP (Figure 2) discussed above. However, it should be appreciated that this may vary for long-length casting. For example, high pressure to let the molten metal to preheat the nozzle and then reduced to maintain stability. In some experimental runs, this overpressure is set at 0.50 bar against the vacuum chamber pressure of about 0.34 bar (i.e., 0.16 pressure difference). As described above, the overpressure AP is used to feed the metallic melt 225 through the nozzle aperture 227. The flow is restricted in the gap G (Figure 2) between the chill surface 205 and the nozzle 222, and the metallic melt forms a puddle of metallic melt 225A having a length L (Figure 2) which is held by surface tension when it comes into contact with the chill surface 205. With sufficient contact between the chill surface 205 and molten puddle 225A, heat is removed from the metallic melt in the molten puddle 225A and solidification occurs. The casting wheel 210 rotates to continually remove the solidified product from the contact-zone forming a foil of solidified metal 230. The formed foil 230 can then be separated from the chill surface 205 (as shown in Figure 5).Applications

[0175] The above described examples of the melt delivery arrangement and associated planar flow casting process and system can be used to produce metallic foils from a variety of metal and metal alloys. Exemplary examples include:1. Precision Thin Metals

[0176] The above described examples of the melt delivery arrangement and associated planar flow casting process and system can be used to produce foils from precision thin metals. As discussed previously, Precision Thin Metals are a group of thin (for example 0.01 to 1.5 mm) and ultra-thin (for example 0.00175 to 0.015 mm) metals and alloys including (but not limited to) stainless steel (Fe) and nonferrous metals / alloys made from or alloyed with titanium (Ti), nickel (Ni), vanadium (V), cobalt (Co), copper (Cu), aluminium (Al), neodymium (Nd) or the like. Precision thin alloys are generally required to have both a thin gauge and a precision of properties.

[0177] It should be appreciated that high-temperature nonferrous alloy foils are a subset of precision thin metals.2. Advanced shape memory performance

[0178] The above described examples of the melt delivery arrangement and associated planar flow casting process and system can be used to produce foils from shape memory alloys (SMAs), such as Nickel-Titanium (Ni-Ti) SMAs. Nickel-Titanium SMAs are smart materials able to recover their original shape under thermal stimulus. The shape-memory special behaviours of NiTi SMAs are due to the martensitic-to-austenitic transformation and its reversion, which can be activated by increasing and decreasing its temperature, respectively

[0179] Most of the commercial SMAs foils produced by the rolling route have a fixed basic microstructure across section of the foils, as a result repetitive thermomechanical processing steps. These SMAs can reliably perform a singlepoint, mostly one-way, actuation - i.e. one-direction and non-reversible motion at one fixed temperature. Consequently, the lack of an effective, reversible actuation ability has limited the use of the SMA actuators to very few simple applications, such as one-off release in QWKNLIT® and Low-Force Nut (LFN), locking or deploying mechanisms for truss mounting folding structures, and deployable hinges of solar panels.

[0180] The PFC foils, however, have exhibited large-degree reversable actions even without training. Different from the thermomechanical process in the rolling manufacturing route, the planar flow casting is a rapid solidification process that quenches metallic melt into solid foils at a high cooling rate between 104°C and 107°C per second, which is the highest at the wheel-side and lowest at the free- side surface of the foil. These characteristics of the cooling rate induce to two type microstructural variations: the formation of additional metastable phase as the result of the high cooling rate and the microstructural transformation from the solution or finer cells to coarser equation grains across section of the foil from the wheel-side to the air-side surface. The variety of the microstructures is considered to the cause for the larger reversible actuation performance by the PFC SMA foils.

[0181] The most common forms of the SMA produced by the existing manufacturing route are wires. Thin SMA foils produced by the PFC process, however, have many advantages over SMA wires, such as generating a large actuation force, a large area that can be formed into various component shapes, etc. In addition, these foils can be used as the feed material to manufacture a greater thickness ranger of foils and sheet materials, such as pack-rolling of multiple layer foils for increasing the thickness to larger than 150 pm or conducting further finish rolling to reduce the thickness to less than 20 pm.

[0182] SMA applications are possible in various areas, for example aerospace and defence, space technology, automotive, sensing and actuating, and biomedical devices, renewable energy, industrial processing, and transport. The use of Ni-Ti SMAs is also possible in miniaturised sensors, actuators and other types of electronics.3. Amorphous metallic foils

[0183] The above described examples of the melt delivery arrangement and associated planar flow casting process and system can be used to produce crystalline or amorphous metallic foils from crystalline or amorphous metals and / or alloys. These metallic materials may comprise one or more high-melting- temperature nonferrous alloy. Specific examples include crystalline and amorphous steels, and crystalline and amorphous, Zr, Mg, Ti, Cu, or the like based or containing alloys.EXAMPLE 1 - Shape Memory Alloy Foil Formation

[0184] A Ni-Ti shape memory alloy (SMA) foil was produced using a planar flow casting apparatus as illustrated in Figure 6. The designated chemistry of the shape memory alloy (SMA) was Ni55.25Ti44.75 (weight %) with a temperature range of 1240 to 1310 °C.

[0185] The source metallic material for the SMA foil was a Ni-Ti alloy ingot which was made by melting Ni and Ti metals of 99.99% purity (4N) in an arc melter.

[0186] A planar flow casting machine (manufactured by PSI Ltd UK), as illustrated in Figure 6, and operated as described above, was used to cast the Ni-Ti SMA foil. The planar flow casting machine used a planar flow casting melt-delivery arrangement 220 following the configuration described and illustrated in relation to Figure 3. This planar flow casting melt-delivery arrangement 220 included a high temperature receptacle 224 made from G347 crucible-grade carbon materials. The nozzle aperture 227 at the bottom of the nozzle 222 was 29 mm long and 0.45 mm wide. A disk filter 246 was positioned 15 mm above the bottom of the nozzle 222. The filter 246 had a 9 mm diameter and 3 mm thickness. The filter 246 included 9 circular filter apertures 250 of 5.5 mm diameter which were uniformly distributed across the disk. Both the filter 246 and internal surfaces of the high temperature receptacle (i.e. both the melting chamber 240 and distribution chamber 242) were spray-coated with BN and then YO2 to provide a ceramic coating thereover.

[0187] The 75 g of Ni-Ti alloy was cut from the Ni-Ti alloy ingot and placed inside the melt chamber 240 of the high temperature receptacle 224. The unit was then assembled inside an atmosphere control chamber 260 (see Figure 5 for schematic view) of the planar flow casting machine (Figure 6). The atmosphere control chamber 260 was operated to remove the oxygen atmosphere using a vacuum pump (not illustrated) and then backfilled with argon. A pyrometer was set up outside of the atmosphere control chamber 260 to monitor the temperature of the top of the nozzle 222 through a glass window set in the planar flow casting machine (not illustrated) which correlated with the temperature of the Ni-Ti alloy within the melt chamber 240 of the high temperature receptacle 224. It should be noted that the actual temperature reading of the pyrometer was only used as a relative indication of the melting temperature during the heating operation once melting starts, as the actual temperature can vary due to the emission changes associated with transformation from solid to liquid.

[0188] The planar flow casting machine included a heating arrangement 228 - an inductive coil - which heated the Ni-Ti alloy within the melt chamber 240 of the high temperature receptacle 224. During the heating, the temperature reading of the pyrometer was found to reach 1000 °C in about 1.5 min. After then, the rateof increase of the temperature reading slowed as a result of ingot melting. In response to this slower heating rate, the heating power supplied by the inductive coil was increased to increase the melting rate - though it should be appreciated that this can be an optional step. Once the temperature reading increased from 1000 °C to 1180 to 1200 °C (typically taking about 1 minute), the heating power was maintained for about 20 seconds. The estimated superheat of the molten alloy at this point was about 50 to 150 °C, before lowering the planar flow casting melt-delivery arrangement 220 into the position for ejection and casting operation.

[0189] The bottom of the nozzle 222 bottom was then lowered to about 0.8 mm above casting wheel 210 rotating at 700 RPM with casting parameters of wheel diameter 296 mm; wheel-nozzle gap: 1.0 mm nozzle slit sizes: 26 mm long and 0.5 mm wide; casting temperature 1194 °C. A pressure of 0.5 bars was applied to eject the molten alloy onto the chilled surface 205 of the casting wheel 210 to produce the shape memory alloy foils of 70 mm width and 80 pm thickness.

[0190] Figure 7 shows one example of Nickel-Titanium (Ni-Ti) shape memory alloy (SMA) foils (Figure 7) formed using a planar flow casting system incorporating a melt delivery arrangement as illustrated in Figure 4, and described above.

[0191] The above example demonstrates that Nickel-Titanium (Ni-Ti) shape memory alloy (SMA) foils of at least 10 mm width (typically 20 to 30 mm), 20 to 150 pm thickness and 1000 to 3000 mm length can be routinely produced by this method at high production rates of 500 to 700 meter length per minute with a precision chemistry and low oxygen level (100 ppm or less). Assuming a PFC machine is equipped with 10 kg melting capability, an estimated cost for producing the high-grade foils of 0.1 mm thickness is about less than 2-3% of the high end of the market price and around 10% of the price offered by the lowest- cost supplier (circa August 2023).EXAMPLE 2 - Amorphous metallic foils

[0192] 30 mm wide and 20 to 30 pm thick Fe amorphous foils may be cast using the methodology set out in example 1 with the following changes in parameters:1. For forming amorphous steel of a specific thickness, such as 20 to 25 pm thickness and 30 mm foils, the width of the nozzle aperture is reduced to 0.2 mm. Different from casting Ti alloy foils of that the thickness, reduction is achieved by increasing speed while keeping aperture width the same at 0.5 mm.2. For the 25 to 30 pm amorphous steel foils, the operation conditions the width of nozzle opening is increased from 0.2 mm to 0.25 mm, while other parameters at, 1600 rpm, of 296 mm diameter, wheel, melting temperature 1100 °C, ejection pressure 0.1 bar, and 0.7 mm gap between wheel and nozzle (rubbing).Example 3 - Zr based amorphous alloy foils

[0193] Planar flow casting Zr based amorphous alloy foils, wheel speed 1050 rpm, wheel-nozzle gap 0.7 mm, ejection pressure 0.4 bar, nozzle aperture (slit) width 0.6 mm and length 30 mm; casting temperature 980 °C, resultant foils of 100 pm thickness.

[0194] Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is understood that the invention includes all such variations and modifications which fall within the spirit and scope of the present invention.

[0195] Where the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification (including the claims) they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the presence of one or more other feature, integer, step, component or group thereof.

Claims

CLAIMS1. A planar flow casting melt-delivery arrangement configured for the production of metallic foils from a metallic material, the melt-delivery arrangement comprising a high temperature receptacle that includes: at least one chamber configured to hold a metallic melt therein; a nozzle having at least one nozzle aperture configured for the egress of the metallic melt from the at least one chamber for foil formation; and at least one filter located within the at least one chamber, each filter configured to remove impurities from the metallic melt flowing therethrough.

2. A planar flow casting melt-delivery arrangement according to claim 1 , wherein the at least one filter comprises a separator body that includes at least one aperture, preferably a ceramic plate or sheet which includes said at least one aperture.

3. A planar flow casting melt-delivery arrangement according to claim 2, wherein at least one of the size, location and number of apertures in the at least one filter is configured to provide a substantially uniform flow of metallic melt when the metallic melt flows through the filter.

4. A planar flow casting melt-delivery arrangement according to claim 2 or 3, wherein the apertures in the at least one filter is substantially evenly distributed across the planar area perpendicular to the longitudinal axis of each filter.

5. A planar flow casting melt-delivery arrangement according to any one of the preceding claims, comprising at least two filters located in the at least one chamber.

6. A planar flow casting melt-delivery arrangement according to claim 5, wherein each filter comprises a separator body that includes at least one aperture, and the apertures of each filter have different aperture sizes.

7. A planar flow casting melt-delivery arrangement according to any one of the preceding claims, wherein the high temperature receptacle comprises a carbonaceous based container.

8. A planar flow casting melt-delivery arrangement according to any one of the preceding claims, wherein the at least one chamber includes an inner high- temperature ceramic layer, and wherein the high-temperature ceramic layer optionally comprises at least one high temperature ceramic selected from at least one of: aluminium oxide (AI2O3), quartz, boron nitride (BN), yttrium oxide (Y2O3), AINi, or a refractory oxide.

9. A planar flow casting melt-delivery arrangement according to any one of the preceding claims, wherein the base of the high temperature receptacle has a lower heat capacity relative to the sidewalls of the high temperature receptacle.

10. A planar flow casting melt-delivery arrangement according to any one of the preceding claims, further comprising at least one heating arrangement operatively associated with the high temperature receptacle, configured to heat the metallic material within the high temperature receptacle to at least the melting point of that metallic material.

11. A planar flow casting melt-delivery arrangement according to any one of the preceding claims, further comprising at least one flow distributor located between the filter and the at least one nozzle aperture.

12. A planar flow casting melt-delivery arrangement according to any one of the preceding claims, wherein the high temperature receptacle includes at least two chambers separated by the at least one filter and a longitudinal axis extending therethrough, said at least two chambers including: a melt chamber comprising a fluid holding space configured to hold a metallic melt therein; and a distribution chamber located axially below the melt chamber relative to the longitudinal axis, which includes a fluid holding space configured to hold a metallic melt therein, and a base that includes the nozzle,wherein the at least one filter is located between the melt chamber and the distribution chamber.

13. A planar flow casting melt-delivery arrangement according to claim 12, wherein the width of the distribution chamber and the at least one nozzle aperture is greater than the width of the melt chamber.

14. A planar flow casting melt-delivery arrangement according to claim 12 or 13, wherein the at least one flow distributor is located in the distribution chamber.

15. A planar flow casting melt-delivery arrangement according to claim 14, further including at least two flow distributors, each flow distributors being spaced apart within the distribution chamber between the filter and the at least one nozzle aperture.

16. A planar flow casting melt-delivery arrangement according to claim 15, wherein the distribution chamber comprises at least two tiered sections of different widths, said widths of the at least two tiered sections providing a progressively larger width size from the melt chamber to the at least one nozzle aperture, and wherein each tiered section optionally includes at least one flow distributor.

17. A planar flow casting melt-delivery arrangement according to any one of claims 11 to 16, wherein the at least one flow distributor comprises a separator body, preferably a ceramic plate or sheet, that includes at least one aperture.

18. A planar flow casting melt-delivery arrangement according to claim 17, wherein the at least one aperture of each flow distributor is aligned with the at least one nozzle aperture, optionally comprising at least two apertures which are linearly aligned with the at least one nozzle aperture, and wherein optionally the apertures may be aligned in a configuration that distributes the metallic melt flows across, preferably in a uniform flow across, the whole length of the at least one nozzle aperture.

19. A planar flow casting melt-delivery arrangement according to any one of claims 12 to 18, wherein the distribution chamber includes an upper section above the flow distributor relative to the at least one nozzle aperture having a first cross-sectional shaped chamber and a lower section below the flow distributor relative to the at least one nozzle aperture which comprises a second cross- sectional shaped chamber that has a different cross-section to the first cross- sectional shaped chamber, that second cross-sectional shaped chamber being configured to conform with and / or extends around the shape of the at least one nozzle aperture, wherein the lower section is optionally configured as a funnel to direct flow towards of the at least one nozzle at the base of the distribution chamber.

20. A planar flow casting melt-delivery arrangement according to any one of the preceding claims, wherein the metallic material comprises at least one of: a precision thin metal or alloy; a shape memory alloy; a stainless steel; a crystalline or amorphous metal or alloy; or a nonferrous or ferrous alloy made from or alloyed with at least one of: titanium (Ti), nickel (Ni), vanadium (V), cobalt (Co), copper (Cu), aluminium (Al), Zirconium (Zr), neodymium (Nd) or other rare earth elements.

21. A planar flow casting melt-delivery arrangement according to any one of the preceding claims, wherein the metallic material comprises at least one recycled metal or metal alloy.

22. A planar flow casting system comprising: a planar flow casting melt-delivery arrangement according to any one of the preceding claims; and a foil formation surface operatively associated with the planar flow casting melt-delivery arrangement onto which metallic melt is distributed from the nozzle of the melt-delivery arrangement for foil formation.

23. A planar flow casting system according to claim 22, wherein the foil formation surface comprises a chill surface.

24. A planar flow casting method of forming a metallic foil comprising: forming a metallic melt of a metallic material within a high temperature receptable; passing the metallic melt through at least one filter located within the high temperature receptable to remove impurities from the metallic melt flowing therethrough, to produce a filtered metallic melt; and feeding the filtered metallic melt through at least one nozzle aperture of the high temperature receptable for foil formation on a foil formation surface.

25. A method of forming a metallic foil according to claim 24, using a planar flow casting system according to any one of claims 22 or 23.

26. A method of forming a metallic foil according to claim 24 or 25, further comprising passing the metallic melt through at least one flow distributor located within the high temperature receptable to redistribute the filtered metallic melt within the high temperature receptable.

27. A metallic foil produced by the method according to any one of claims 24 to 26.

28. A planar flow cast metallic foil, preferably which is defect free, comprised of at least one of: a precision thin metal or alloy; a shape memory alloy; a stainless steel; a crystalline or amorphous metal or alloy; or a nonferrous or ferrous alloy made from or alloyed with at least one of: titanium (Ti), nickel (Ni), vanadium (V), cobalt (Co), copper (Cu), aluminium (Al), Zirconium (Zr), neodymium (Nd), or other rare earth elements.

29. A planar flow cast metallic foil according to claim 28, comprising at least one of:a width of at least 10 mm; a length of at least 300 mm; a thickness of from 10 to 200 pm; or a thickness of from 0.01 to 0.5 mm.

30. A planar flow cast metallic foil according to claim 28, comprising at least one of: a width of at least 75 mm; and a length of at least 1000 mm.

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