Additive Friction Stir Deposition onto Cold-Sprayed Barrier Layers

Abstract

A method of manufacturing an article is described. In S102, the method comprises obtaining a first layer having a first surface and an opposing second surface, where the first layer comprises and / or is the first metal, the first metal being a heat-treatable first aluminum alloy. In S104, the method comprises providing a second layer on the first surface of the first layer by cold spraying particles thereon comprising a second metal, where the second metal is a second aluminum alloy. In S106, the method comprises depositing a third layer on the second layer by additive friction stir deposition using a third metal, where the third metal is a third aluminum alloy.

Description

[Technical field]

[0001] The present invention relates to additive friction stir deposition. [Background technology]

[0002] Deposition of high strength non-heat treatable alloys, e.g. Scalmalloy (RTM), onto Al-Zn alloy plates (i.e. substrates), e.g. 7xxx plates such as 7050 T7651, using additive friction stir deposition (also known as MELD) results in high levels of thermal softening of the plate, even though the as-deposited strength of the Scalmalloy deposit is good. The challenge is therefore to avoid thermal degradation at the interface and into the 7xxx substrate. Reduction options include pre-cooling the substrate and / or depositing the substrate in a freshly solution treated state. Both of these options are seen to improve rather than solve the problem and are very difficult to achieve. Cooling the substrate involves significant expense and introduces thermal strain / stress issues with subsequent temperature normalization. Deposition in either the T351 or W51 state (2xxx or 7xxx alloys, respectively) provides only limited relaxation at the heat affected zone boundary, which would otherwise result in overaging. The primary softening directly adjacent to the deposit would likely only be slightly reduced. For the 7xxx options, the W51 condition is also unstable, so the plate will likely need to be refrigerated after solution treatment / drawing (at the plate mill) and then shipped at <-40°C, possibly between North America and Europe. Also, pre-processing under refrigeration prior to additive friction stir deposition would be extremely difficult and costly.

[0003] Nevertheless, there is a need to improve additive friction stir deposition. Summary of the Invention

[0004] According to a first aspect of the present invention there is provided a method of manufacturing an article, the method comprising the steps of: obtaining a first layer having a first surface and an opposing second surface, wherein the first layer comprises and / or is a first metal, the first metal being a heat-treated first aluminum alloy; providing a second layer on the first surface of the first layer by cold spraying particles having a second metal thereon, wherein the second metal is a second aluminum alloy; depositing a third layer on the second layer by additive friction stir deposition using a third metal, wherein the third metal is a third aluminum alloy; Equipped with.

[0005] According to a second aspect of the present invention, a first layer, wherein the first layer comprises and / or is a first metal, the first metal being a heat-treatable first aluminum alloy; a second layer on the first layer, wherein the second layer comprises cold sprayed particles comprising a second metal thereon, the second metal being a second aluminum alloy; a third layer on the second layer, wherein the third layer comprises and / or is a third metal of the additive friction stir deposition, the third metal being a third aluminum alloy; An article is provided comprising:

[0006] According to a third aspect of the invention, there is provided the use of a cold-sprayed layer of an Al-Mg-(Sc,Zr) based alloy on a heat-treatable aluminium alloy as a barrier layer.

[0007] According to a fourth aspect of the present invention there is provided a method of manufacturing an article, the method comprising the steps of: obtaining a first layer having a first surface and an opposing second surface, wherein the first layer comprises and / or is a first metal, the first metal being a heat-treated first aluminum alloy; providing a second layer on the first surface of the first layer by cold spraying particles having a second metal thereon, wherein the second metal is a second aluminum alloy; depositing a third layer on the second barrier layer by additive friction stir deposition using a third metal, wherein the third metal is a third aluminum alloy, the second layer is a barrier layer, and the heat treatable first aluminum alloy is heat treated to a T or W temper designation prior to applying the second layer thereon. Equipped with.

[0008] According to a fifth aspect of the present invention, there is provided the use of a cold sprayed layer of an Al-Mg-(Sc,Zr) based alloy on a heat treatable aluminium alloy as a barrier layer, wherein the barrier layer is between the heat treatable aluminium alloy and the additive friction stir deposited aluminium alloy. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] According to a first aspect of the present invention there is provided a method of manufacturing an article, the method comprising the steps of: obtaining a first layer having a first surface and an opposing second surface, wherein the first layer comprises and / or is a first metal, the first metal being a heat-treated first aluminum alloy; providing a second layer on the first surface of the first layer by cold spraying particles having a second metal thereon, wherein the second metal is a second aluminum alloy; depositing a third layer on the second layer by additive friction stir deposition using a third metal, wherein the third metal is a third aluminum alloy; Equipped with.

[0010] In this manner, the second layer provides a thermal barrier between the relatively hot but solid state additive friction stir deposition process and the heat treated first aluminum alloy of the first layer, thereby mitigating or avoiding its thermal softening. In this manner, the relatively high deposition rates of additive friction stir deposition can be utilized without degrading the properties of the first layer. The second layer is incorporated (i.e., integral) into the article and can be the same aluminum alloy as the third layer. The method is a method for manufacturing an article. In one example, the article comprises and / or is an aerospace part, such as an airframe part, a vehicle part, such as an engine part, or a medical part, such as an implantable medical device.

[0011] The method comprises obtaining a first layer having a first surface and an opposing second surface, where the first layer comprises and / or is a first metal. In one example, the first layer comprises and / or is a plate or extrusion that undergoes controlled stretching during its manufacture, for example. It should be understood that the first layer provides or is a substrate for cold spraying, as described below.

[0012] The first metal is a heat-treatable first aluminum alloy. In one example, the heat-treatable first aluminum alloy is a 2XXX, 6XXX, 7XXX, or 8XXX series forged aluminum alloy. 2XXX, 6XXX, 7XXX, or 8XXX series forged aluminum alloys are known.

[0013] In one example, the first aluminum alloy of heat treatable type is heat treated in a T or W temper designation (i.e., to a T or W temper designation) before applying the second layer thereon. In one example, the method comprises heat treating the first aluminum alloy of heat treatable type in a T or W temper designation before applying the second layer thereon. In this manner, the first aluminum alloy of heat treatable type is heat treated in a T or W temper designation before applying the second layer thereon by cold spray. That is, the T or W temper designation is not adversely affected or affected by the cold spray. In one example, the first layer comprises and / or is and / or is formed from a plate, and the T designation is T351 (e.g., 2024, 2014, 2014A, 2050, etc.), T651, T851, T7651, T7451, or T77351. In one example, the first layer comprises and / or is and / or is formed from a plate, and the W designation is W51 (e.g., for a 7XXX alloy). In one example, the first layer comprises and / or is and / or is formed from an extrusion, and the T designation is T3511, T6511, T8511, T76511, T74511, or T73511 (the final "1" here referring to straightening after drawing). In one example, the first layer comprises and / or is and / or is formed from an extrusion, and the W designation is W511 (e.g., for a 7XXX alloy).

[0014] The method comprises providing a second layer on a first surface of the first layer by cold spraying thereon particles including a second metal, hi one example, the particles are of the second metal (i.e., the particles consist essentially of or consist of the second metal).

[0015] Cold spray (also known as gas dynamic cold spray) is a known deposition process. Particles (typically with a particle size in the range of 1-50 μm diameter, preferably 10-40 μm diameter) are all sprayed with a supersonic gas jet (typically He and / or N2) over a period of 1200 ms from an injection nozzle. -1 The particles are accelerated to velocities of up to 1000 rpm and impact a substrate, such as a second surface. Upon impact, the particles are plastically deformed and bond to it. A uniform layer is achieved by scanning or rastering the spray nozzle. Relatively thick layers can be achieved by repeated cold spraying, and deposition rates can be relatively high. High pressure cold spray (HPCS) is used with pressures of over 1.5 MPa, 2 m 3 It uses nitrogen or helium at flow rates exceeding 1 / min and a firing power of about 15-20 kW. HPCS is typically used to spray metal particles with diameters of 5-50 μm. Low pressure cold spray (LPCS) uses pressures of 0.5-1.0 MPa, a flow rate of 0.5-2 m 3 It uses compressed gas with a flow rate of 100000 / min, and a firepower of 3-5 kW. LPCS may be used to spray a mixture of metal and ceramic particles. By including a ceramic component in the mixture, a high quality coating is obtained with relatively low energy consumption. Unlike thermal spraying (such as plasma spraying, arc spraying, flame spraying, or high velocity oxy-fuel spraying), the particles do not melt during cold spraying. Rather, the heat input during cold spraying is relatively low, thereby reducing or eliminating residual stresses in the substrate and / or its deformation. Additionally, cold sprayed layers have low porosity, which is typically closed (i.e., not interconnected).

[0016] In one example, the cold spray comprises cold spray using helium. In one example, the cold spray comprises cold spray using, for example, a pressure of more than 1.5 MPa, 2 m 3 It is equipped with a high-pressure cold spray using He with a flow rate of over 1 / min and a thermal power of approximately 15 to 20 kW.

[0017] In one example, providing a second layer on a first surface of the first layer by cold spraying particles having a second metal thereon comprises providing a second layer only on the first surface of the first layer by cold spraying particles having a second metal thereon on the first surface of the first layer, i.e., the method excludes cold spraying a second layer on an opposing second surface of the first layer, i.e., cold spraying on one surface.

[0018] In one example, the method comprises providing a second layer on a second surface opposite the first layer by cold spraying particles having a second metal thereon, i.e., the method includes cold spraying the second layer on a second surface opposite the first layer, i.e., cold spraying on both sides.

[0019] In one example, providing a second layer on the first surface of the first layer by cold spraying particles having a second metal thereon comprises selectively cold spraying the first surface, e.g., selectively cold spraying on selected areas of the first surface. In this manner, the second surface may be selectively cold sprayed, e.g., to provide the second layer in desired areas, e.g., to provide the second layer only in desired areas.

[0020] In one example, cold spraying particles comprising a second metal onto the first surface comprises cold spraying particles comprising a second metal onto at least 50%, 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, or 99% of the area of ​​the first surface. In one example, cold spraying particles comprising a second metal onto the first surface comprises cold spraying particles comprising a second metal onto the entire first surface.

[0021] In one example, cold spraying particles comprising a second metal onto the first surface comprises cold spraying particles comprising a second metal directly onto the first surface, i.e., without an intermediate layer therebetween. In one example, cold spraying particles including a second metal onto the first surface comprises cold spraying particles comprising a second metal indirectly onto the first surface, i.e., with an intermediate layer therebetween.

[0022] The second metal is a second aluminum alloy. In one example, the second aluminum alloy is a heat-treatable second aluminum alloy. In one example, the heat-treatable second aluminum alloy is a 2XXX, 6XXX, 7XXX, or 8XXX series wrought aluminum alloy. In one example, the second aluminum alloy is a non-heat-treatable second aluminum alloy. In one example, the non-heat-treatable first aluminum alloy is a 5XXX series aluminum alloy. In one example, the non-heat-treatable second aluminum alloy is an Al-Mg-Sc alloy, such as 5028, an Al-Mg-Zr alloy, an Al-Mg-Sc-Zr alloy, or an Al-Mg-Zr-Sc alloy, generally Al-Mg-(Zr,Sc) containing one or both of Zr and Sc, and optionally containing Er. In general, the addition of scandium (typically 0.1% to 0.5% by weight) to aluminum alloys results in the precipitation of nanoscale Al3Sc precipitates. The nanoscale Al3Sc precipitates increase the yield strength of the alloy by 50 to 70 MPa. The nanoscale Al3Sc precipitates limit excessive grain growth in the heat-affected zone of welded aluminum alloy components. This has two beneficial effects: the nanoscale Al3Sc precipitates are smaller than other precipitates that form in other aluminum alloys, reducing the width of the precipitate-free zones that are normally present at the grain boundaries of age-hardenable aluminum alloys. Scandium is also a strong grain refiner in cast aluminum alloys and, atomically, is the most powerful strengthener in aluminum, both as a result of grain refinement and precipitation strengthening. The nanoscale Al3Sc precipitates are resistant to coarsening at relatively high temperatures (around 350°C), in contrast to typical commercial 2xxx and 6xxx alloys, which lose strength rapidly at temperatures above 250°C due to the rapid coarsening of their strengthening precipitates. The addition of erbium and zirconium has been shown to increase the coarsening resistance of Al-Sc alloys up to around 400°C. This is accomplished by forming a slowly diffusing zirconium-rich shell around a scandium- and erbium-rich precipitate core, forming strengthening precipitates with the composition Al3(Sc,Zr,Er).Further improvements in coarsening resistance allow these aluminum alloys to be used at increasingly higher temperatures. In a preferred example, the non-heat-treatable second aluminum alloy is Scalmalloy (RTM) (available from APWORKS GmbH, Germany), e.g., CT PR SCALMALLOY F. Scalmalloy is typically made by nitrogen gas atomization and supplied as a powder with a typical composition as summarized in Table 1 and a typical particle size distribution as summarized in Table 2.

[0023] [Table 1]

[0024] [Table 2]

[0025] In one example, the particles comprising the second metal have a particle size range (i.e., distribution) of 1-500 μm, preferably at least 46, 51, 61, 64, 101 or 151 μm, for example, preferably 64-250 μm or 101-250 μm. Typical particle size ranges for melting or sintering additive manufacturing processes are: selective laser melting (SLM), also known as laser PBF, LPBF, or L-PBF: 20-60 μm; selective laser sintering (SLS): 15-45 μm; directed energy deposition (DED): 50-150 μm; electron beam melting (EBM): 50-150 μm; laser beam melting (LBM) 10-60 μm; spray deposition 5-50 μm. Skalmalloy is typically available in particle size ranges of 20-63 μm and 20-100 μm. That is, preferably, the particles comprising the second metal are too large compared to typical particle size ranges for such melting or sintering additive manufacturing processes, e.g., LPBF, so that the particles comprising the second metal can be sourced as a by-product of typical fabrication.Generally, particle size ranges may be determined in accordance with ASTM F3049 - 14 Standard Guide for Characterizing Properties of Metal Powders Used for Additive Manufacturing Processes and standards referenced therein; ASTM E2651 - 19 Standard Guide for Powder Particle Size Analysis; ASTM B214 - 16 Standard Test Method for Sieve Analysis for Metal Powders; ASTM B822 - 20 Standard Test Method for Particle Size Distribution of Metal Powders and Related Compounds by Light Scattering; ISO / ASTM52907 - 19 Additive manufacturing - Feedstock materials - Methods to characterize metallic powders. It is understood that most particle size analysis techniques report particle size in terms of the "equivalent spherical diameter."

[0026] In one example, the thickness of the second layer is determined, at least in part, by the heat input during deposition of the third layer.

[0027] In one example, the ratio of the respective thicknesses of the second layer and the third layer is in the range of 1:2 to 2:1.

[0028] In one example, the thickness of the second layer is in the range of 1 mm to 20 mm, preferably in the range of 3 mm to 15 mm, and more preferably in the range of 7 mm to 10 mm.

[0029] Generally, cold spray deposit thickness is at least 3mm, and likely 10-12mm, or even more. Optimum thickness is expected to be around 7mm-10mm, based on the depth of the HAZ seen on 7050 plates. MELD deposit thickness can be thicker than cold spray, and in some cases, depending on many factors, can actually be very thick, with almost no limit (e.g., several 100mm). Thus, in a typical application, we would see 10mm cold spray deposits and MELD deposits that could range from as little as 10mm to perhaps >200mm, and even >>200mm.

[0030] The method comprises depositing a third layer on the second layer by additive friction stir deposition using a third metal, where the third metal is a third aluminum alloy.

[0031] It is understood that the second metal and the third metal are mutually compatible such that the third metal can be deposited on the second metal by additive friction stir deposition. It is understood that mutual compatibility does not require compositional and / or chemical compatibility because additive friction stir deposition is a solid state process, as described below.

[0032] It should be understood that depositing a third layer on a second layer excludes fusion deposition.

[0033] Additive friction stir deposition (AFSD) (also known as friction stir deposition or MELD (RTM)) is a known deposition process based on friction stir welding. Additive friction stir deposition is a low-temperature solid-state process. This solid-state deposition process shares some similarities with other high-shear and high-temperature solid-state processes, such as shear extrusion or friction stir welding and processing (FSW / P), but differs significantly in that the feedstock material (i.e., the third metal) is fed through a rotating hollow tool and deposited onto a substrate (i.e., the second layer) while the feedstock remains entirely in a solid state. The feedstock, which can be in rod (typically round or square) or powder form, is extruded through a non-consumable rotating cylindrical tool. The rotation and feeding generates heat and plastically deforms the feedstock under controlled pressure from the tool while successive layers are deposited onto the substrate. Once a layer is added, the tool is lifted to begin deposition of successive layers on top of it, creating a strong metallurgical bond between the layers. Benefits of additive friction stir deposition include grain refinement, homogenization, and reduced porosity. Typically, additive friction stir deposition results in a wrought microstructure. The deposited material is dense enough that de-binding, sintering, or HIPing is not required. Because additive friction stir deposition is a solid-state process, problems such as porosity, hot cracking, elemental segregation, and dilution (typically associated with fusion-based processes) are reduced or eliminated, since the material(s) do not solidify from a liquid phase. During additive friction stir deposition processing, the temperature is similar to that in the stir zone (SZ) of FSW and is estimated to be 0.6-0.9 Tm, where Tm is the melting point of the material(s). Additive friction stir deposition is a highly scalable process, with temperatures reaching temperatures of up to 1000 cm for aluminum alloys. 3It has a relatively high deposition rate of over 10000 sq. m / h, allowing for the repair, coating, and / or building of fully dense materials, including relatively large articles in three dimensions. Because additive friction stir deposition is a solid-state process, it avoids the controlled atmosphere chambers and powder beds of fused deposition processes such as laser powder bed fusion bonding. Because additive friction stir deposition is a solid-state process, residual stresses are reduced.

[0034] In one example, the third aluminum alloy is a heat-treatable third aluminum alloy. In one example, the heat-treatable third aluminum alloy is a 2XXX, 6XXX, 7XXX, or 8XXX series forged aluminum alloy. In one example, the third aluminum alloy is a non-heat-treatable third aluminum alloy. In one example, the non-heat-treatable first aluminum alloy is a 5XXX series aluminum alloy. In one example, the non-heat-treatable third aluminum alloy is an Al-Mg-Sc alloy such as 5028, an Al-Mg-Zr alloy, an Al-Mg-Sc-Zr alloy, or an Al-Mg-Zr-Sc alloy, generally an Al-Mg-(Zr,Sc) alloy containing one or both of Zr and Sc, and optionally containing Er. In a preferred example, the non-heat-treatable second aluminum alloy is a skalmalloy. The third aluminum alloy may be as described for the second aluminum alloy.

[0035] In one example, depositing a third layer onto the second layer by additive friction stir deposition using a third metal includes depositing the third layer onto the second layer by additive friction stir deposition of successive (i.e., multiple) layers using the third metal.

[0036] In one example, depositing a third layer on the second layer by additive friction stir deposition using a third metal includes depositing a third layer on the second layer by additive friction stir deposition using particles of the third metal. In one example, the particles are of the third metal (i.e., the particles consist essentially of or consist of the third metal). In one example, the particles of the third metal have a particle size range (i.e., distribution) of 1 to 500 μm, preferably at least 46, 51, 61, 64, 101 or 151 μm, such as, preferably, 64 to 250 μm or 101 to 250 μm. Typical particle size ranges for melting or sintering additive manufacturing processes are: selective laser melting (SLM), also known as laser PBF, LPBF, or L-PBF: 20-60 μm; selective laser sintering (SLS): 15-45 μm; directed energy deposition (DED): 50-150 μm; electron beam melting (EBM): 50-150 μm; laser beam melting (LBM) 10-60 μm; spray deposition 5-50 μm. Skarmalloi is typically available in particle size ranges of 20-63 μm and 20-100 μm. That is, preferably, the particles of the third metal may be supplied as a by-product of a typical fabrication, since the particles of the third metal are too large compared to the typical particle size ranges for such melting or sintering additive manufacturing processes, e.g., LPBF. The particles of the third metal may be as described for the particles of the second metal.

[0037] In one example, the method comprises aging before and / or after providing the second and / or third layers, in this way the mechanical properties of the layers can be improved.

[0038] In one example, the ratio of the respective hardnesses of the first layer before and after depositing the third layer, e.g., before and after providing the second layer and depositing the third layer, is in the range of 1:0.50 to 1:1.50, preferably in the range of 1:0.75 to 1:1.25, more preferably in the range of 1:0.90 to 1:1.10. That is, the hardness of the first layer is not substantially affected by depositing the third layer because of the presence of the second layer in between. It should be understood that the change in hardness is related to the deposition of the third layer, not, for example, aging and / or heat treatment. For example, if the first layer is, for example, 7050 W51 before deposition, and the cold spray deposition completely protects the first layer from the heat of the third layer, the hardness should not change, and therefore the ratio is about 1:1. However, W51 is, by definition, unstable, so the hardness increases after a long time from solution processing and controlled stretching. Conversely, the hardness may actually increase after deposition, but simply due to the passage of time, as the hardness is relatively low over short time intervals and increases with time, and not as a result of the deposition. Alternatively, the treatment could be applied to, for example, a 2014A plate in the T351 condition, then age hardened to the T851 condition after cold spray and MELD deposition, and an increase in hardness could be seen, but again, the hardness of the substrate plate should not be affected by the deposition treatment.

[0039] In one example, the method comprises: providing a fourth layer on a second surface opposite the first layer by cold spraying particles having a second metal thereon, wherein the second metal is a second aluminum alloy; depositing a fifth layer on the fourth layer by additive friction stir deposition using a third metal, wherein the third metal is a third aluminum alloy; Equipped with.

[0040] That is, the cold spray layer and the additive friction stir deposited layer are applied on both sides (i.e., both sides). Applying the fourth layer and depositing the fifth layer may be as described for applying the second layer and depositing the third layer, respectively, mutatis mutandis.

[0041] According to a second aspect of the present invention, a first layer, wherein the first layer comprises and / or is a first metal, the first metal being a heat-treatable first aluminum alloy; a second layer on the first layer, wherein the second layer comprises cold sprayed particles comprising a second metal thereon, the second metal being a second aluminum alloy; a third layer on the second layer, wherein the third layer comprises and / or is a third metal of the additive friction stir deposition, the third metal being a third aluminum alloy; An article is provided comprising:

[0042] According to a third aspect of the invention, there is provided the use of a cold-sprayed layer of an Al-Mg-(Sc,Zr) based alloy on a heat-treatable aluminium alloy as a barrier layer.

[0043] Throughout this specification, the terms "comprising" or "comprises" mean including the specified component(s) but not excluding the presence of other components. The terms "consisting essentially of" or "consists essentially of" mean including the specified components but excluding other components, except for materials present as impurities, unavoidable materials present as a result of processes used to provide the component, and components added for purposes other than achieving the technical effect of the invention, such as colorants.

[0044] The terms "consisting of" or "consists of" mean the inclusion of the specified components, but the exclusion of other components.

[0045] Wherever appropriate and depending on the context, use of the terms "comprises" or "comprising" may be interpreted to include the meanings "consisting essentially of" or "consisting essentially of," as well as "consists of" or "consisting of."

[0046] The optional features described herein may be used individually or in combination with each other, where appropriate, in particular in the combinations described in the appended claims. The optional features of each aspect or exemplary embodiment of the invention described herein are also applicable to all other aspects or exemplary embodiments of the invention, where appropriate. In other words, a person skilled in the art reading this specification should consider the optional features of each aspect or exemplary embodiment of the invention to be interchangeable and combinable between different aspects and exemplary embodiments. [Brief description of the drawings]

[0047] Embodiments of the present invention will now be described, by way of example only, with reference to the drawings, in which: [Figure 1] FIG. 1 illustrates a method according to an example embodiment. [Diagram 2] FIG. 2 illustrates a method according to an exemplary embodiment in more detail. [Diagram 3] FIG. 3 illustrates the method of FIG. 2 in more detail. [Figure 4] FIG. 4 illustrates the method of FIG. 2 in more detail. [Diagram 5] FIG. 5 illustrates an article according to an exemplary embodiment. Detailed Description of the Drawings

[0048] 1 illustrates a method 100 according to an exemplary embodiment. The method is a method for manufacturing an article.

[0049] At S102, the method comprises obtaining a first layer having a first side and an opposing second side, where the first layer comprises and / or is a first metal, the first metal being a heat-treatable first aluminum alloy.

[0050] At S104, the method comprises providing a second layer on the first surface of the first layer by cold spraying particles having a second metal thereon, where the second metal is a second aluminum alloy.

[0051] At S106, the method comprises depositing a third layer on the second layer by additive friction stir deposition using a third metal, where the third metal is a third aluminum alloy.

[0052] The method may include any of the steps described in relation to the first aspect.

[0053] 2 illustrates in more detail a method according to an exemplary embodiment. The method is a method of manufacturing an article. The method comprises obtaining a first layer 10 having a first side 11 and an opposing second side 12, where the first layer 10 comprises and / or is a first metal, the first metal being a heat-treatable first aluminum alloy.

[0054] Figure 3 shows in more detail the method of Figure 2. The method comprises providing a second layer 20 on the first surface 11 of the first layer 10 by cold spraying particles 23 having a second metal thereon, where the second metal is a second aluminum alloy.

[0055] Figure 4 illustrates in more detail the method of Figure 2. The method comprises depositing a third layer 30 on the second layer 20 by additive friction stir deposition 34 using a third metal, where the third metal is a third aluminum alloy.

[0056] FIG. 5 shows an article 5 according to a comparative example.

[0057] More specifically, Figure 5 shows a photograph of a Rockwell "B" hardness survey of an Al-Mg-Sc alloy (i.e., third layer) deposited (i.e., directly) on a 7050 substrate (i.e., first layer) by additive friction stir deposition. Although no scale is shown and the interface location must be inferred, the HAZ appears to be approximately 10 mm deep.

[0058] The solution identified is to deposit an intermediate layer of scale malloy (i.e. the second layer between the first and third layers) by cold spraying directly from the powder state. This intermediate layer forms a thermal barrier between the (high temperature) MELD process and the (room temperature) 7xxx substrate. The thickness of the intermediate layer is 5-10 mm.

Claims

1. 1. A method of manufacturing an article, comprising the steps of: obtaining a first layer having a first surface and an opposite second surface, wherein the first layer comprises and / or is a first metal, the first metal being a heat-treated first aluminum alloy (102); providing a second layer on the first surface of the first layer by cold spraying particles having a second metal thereon, wherein the second metal is a second aluminum alloy (104); depositing a third layer on the second layer by additive friction stir deposition using a third metal, wherein the third metal is a third aluminum alloy (106); the second layer is a barrier layer; the heat-treatable first aluminum alloy is heat-treated to a T or W temper designation prior to providing the second layer thereon; A method comprising:

2. 2. The method of claim 1, wherein the heat treatable first aluminum alloy is a 2XXX, 6XXX, 7XXX, or 8XXX series wrought aluminum alloy.

3. The method according to claim 1 or 2, wherein the second aluminum alloy is a non-heat-treatable second aluminum alloy.

4. 4. The method according to claim 3, wherein the second aluminum alloy of non-heat-treatable type is an Al-Mg-Sc based alloy, an Al-Mg-Zr based alloy, an Al-Mg-Sc-Zr based alloy, or an Al-Mg-Zr-Sc based alloy.

5. 5. The method of claim 1, wherein the thickness of the second layer is determined, at least in part, by the heat input during deposition of the third layer.

6. The method of claim 5, wherein a ratio of the respective thicknesses of the second layer and the third layer is in the range of 1:2 to 2:

1.

7. The method according to claim 5 or 6, wherein the thickness of the second layer is in the range of 1 mm to 20 mm.

8. 8. The method of claim 1, wherein the cold spraying comprises cold spraying with helium.

9. 9. The method according to claim 1, wherein the third aluminum alloy is a non-heat-treatable third aluminum alloy.

10. The method of claim 7, wherein the third aluminum alloy is an Al-Mg-Sc based alloy, an Al-Mg-Zr based alloy, an Al-Mg-Sc-Zr based alloy, or an Al-Mg-Zr-Sc based alloy.

11. 11. The method of any one of claims 1 to 10, comprising ageing before and / or after providing the second layer and / or the third layer.

12. 12. The method according to any one of the preceding claims, wherein the ratio of the respective hardnesses of the first layer before and after depositing the third layer is in the range of 1:0.75 to 1:1.

25.

13. 1. Use of a cold sprayed layer of an Al-Mg-(Sc,Zr) based alloy on a heat treatable aluminium alloy as a barrier layer, said barrier layer being between said heat treatable aluminium alloy and an additive friction stir deposited aluminium alloy.

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