Homogenizing non-uniform foils for light-weight alloy metal parts

Abstract

A method for manufacturing an object. The method includes receiving a desired alloy composition for the object; stacking a plurality of foils in a stack to form the object; applying heat to the stack at a first temperature to bond the plurality of foils to one another; and applying heat to the stack at a second temperature to homogenize the composition of the stack. The homogenized stack has the desired alloy composition. In some embodiments, the plurality of foils are patterned. In some embodiments, the plurality of foils includes foils having at least two different compositions.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. Patent Application No. 18 / 482,866, filed October 7, 2023, which is itself a divisional of U.S. Patent Application No. 18 / 131,340, filed April 5, 2023, which is itself a continuation-in-part of International (PCT) Patent Application No. PCT / US2021 / 065196, filed December 27, 2021, which is a continuation-in-part of U.S. Provisional Application Nos. 18 / 482,866, filed October 7, 2023, and 18 / 131,340, filed December 27, 2021, respectively. This application claims the benefit of and priority to International (PCT) Patent Application Nos. 63 / 131,285 and 63 / 257,091, and International (PCT) Patent Application Nos. PCT / US2021 / 030879 and PCT / US2021 / 036770, filed May 5, 2021 and June 10, 2021, respectively, the entire disclosures of each of which are incorporated herein by reference as if set forth in their entirety.

[0002] Technical Field The embodiments described herein relate to methods and systems for manufacturing an object, and more particularly, but not exclusively, to methods and systems for manufacturing an object having a desired alloy composition from a stack of foils having a composition different from the desired alloy composition. [Background technology]

[0003] background Laminated object manufacturing (LOM) techniques generally involve stacking foils composed of layers of at least two alloys and bonding the foils together to create a solid object. Parts assembled by conventional LOM techniques have different compositions at the foil-to-foil bond regions and at the structural components of the foils, alternating throughout the bulk of the part. Due to these compositional gradients throughout the part, the mechanical properties of composite parts assembled by LOM may not equal those predicted by the average composition of the alloys.

[0004] Therefore, there is a need for improved LOM techniques. Summary of the Invention [Means for solving the problem]

[0005] overview This Summary is presented to introduce a selection of concepts in a simplified form that are further described in the Detailed Description section below. This Summary is not intended to identify or exclude key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

[0006] According to one aspect, an embodiment relates to a method for manufacturing an object, the method including receiving a desired alloy composition for the object; stacking a plurality of foils in a stack to form the object; applying heat to the stack at a first temperature to bond the plurality of foils to one another; and applying heat to the stack at a second temperature to homogenize the composition of the stack, wherein the homogenized stack has the desired alloy composition.

[0007] In some embodiments, the plurality of foils are patterned.

[0008] In some embodiments, the plurality of foils includes foils having at least two different compositions.

[0009] In some embodiments, each foil comprises multiple layers. In some embodiments, each layer comprises an aluminum alloy, a magnesium alloy, or a titanium alloy. In some embodiments, the alloy material is aluminum, chromium, copper, lithium, magnesium, titanium, nickel, silicon, or zinc. In some embodiments, a first layer forms the core of the foil and a second layer forms the cladding of the foil.

[0010] In some embodiments, each foil is between 25 and 1000 micrometers thick.

[0011] In some embodiments, the second temperature is below the melting point of the plurality of foils.

[0012] In some embodiments, the second temperature is about equal to or less than the solidus temperature of the plurality of foils of the desired alloy composition.

[0013] In some embodiments, the first temperature and the second temperature are the same.

[0014] In some embodiments, the heating at the first temperature occurs in a first processing unit and the heating at the second temperature occurs in a second processing unit, hi some embodiments, the laminate is maintained at the first temperature during movement from the first processing unit to the second processing unit.

[0015] In some embodiments, the method further comprises quenching the laminate after homogenization, hi some embodiments, the quenching is performed in the same processing unit used to homogenize the laminate.

[0016] In some embodiments, the desired alloy composition is a uniform composition that is not the same as the composition of the multiple foils.

[0017] Non-limiting and non-exhaustive embodiments of the present disclosure are described with reference to the following drawings, in which like reference numerals refer to like parts throughout the various drawings unless otherwise specified. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 illustrates a cross-sectional view of a metal laminate body produced according to one embodiment.

[0019] [Figure 2] FIG. 2 illustrates a triangular view and an object view of the metal laminate object of FIG. 1 according to one embodiment.

[0020] [Figure 3] FIG. 3 illustrates a cross section of an individual foil according to one embodiment.

[0021] [Figure 4A] 4A-D illustrate various configurations of foils according to several embodiments. [Figure 4B] Same as above. [Figure 4C] Same as above. [Figure 4D] Same as above.

[0022] [Figure 5] FIG. 5 illustrates the concentration profile of the interface between the intermediate layer and two core layers, according to one embodiment.

[0023] [Figure 6] FIG. 6 illustrates an operational profile of the homogenization process according to one embodiment.

[0024] [Figure 7] FIG. 7 illustrates a flow diagram of a method for manufacturing an object, according to one embodiment.

[0025] [Figure 8]FIG. 8 illustrates an additive manufacturing system including two plates configured to apply at least one of heat and pressure to a layer stack to bond layers in the layer stack, according to one embodiment.

[0026] [Figure 9] FIG. 9 illustrates a schematic of a method for additive manufacturing of an object by diffusion bonding according to one embodiment.

[0027] [Figure 10] FIG. 10 illustrates a schematic of a method for additive manufacturing of an object by transient liquid phase (TLP) diffusion bonding according to one embodiment.

[0028] [Figure 11] FIG. 11 illustrates a schematic diagram of a method for additive manufacturing of an object by brazing according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0029] Detailed Description Various embodiments are described more fully below with reference to the accompanying drawings, which form a part hereof and which show specific exemplary embodiments. However, the concepts of the present disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are presented as part of a thorough and complete disclosure to fully convey the scope of the concepts, techniques, and implementations of the present disclosure to those skilled in the art. The embodiments may be implemented as a method, system, or device. Thus, the embodiments may take the form of a hardware implementation, an entirely software implementation, or an implementation combining software and hardware aspects. Therefore, the following detailed description should not be taken in a limiting sense.

[0030] References herein to "one embodiment" or "embodiments" mean that the particular features, structures, or characteristics described in connection with these embodiments are included in at least one example implementation or technique according to this disclosure. Appearances of the phrase "in one embodiment" in various places in this specification do not necessarily all refer to the same embodiment.

[0031] Furthermore, the language used herein may have been selected primarily for ease of reading and instructional purposes, and not to outline or limit the disclosed subject matter. Thus, the present disclosure is intended to illustrate, but not limit, the scope of the concepts discussed herein.

[0032] Embodiments of the present invention include methods used to homogenize the composition of lightweight alloy laminate components. These laminate components may be the product of a LOM process. In some embodiments, the component may include multiple foils joined together by a process, each foil having at least one core layer and at least one interlayer. In other embodiments, the component may include multiple foils joined together by a process, with alternating foils having uniform core layers and uniform interlayers. In some embodiments, the process comprises applying heat for a predetermined processing time to promote solid-state diffusion of alloying elements throughout the bulk of the component. In some embodiments, solid-state diffusion homogenizes the composition of alloying elements throughout the bulk of the component to improve the mechanical properties of components produced by LOM. In embodiments of the method, material is added to the component in insignificant amounts.

[0033] In some embodiments, both the composition and relative ratios of the constituent layers making up the foil are selected so that a fully homogenized part has an average composition corresponding to the target alloy. Two or more layers of different alloys combined and homogenized using this method can produce a third alloy, depending on the composition and thickness of the constituent layers. In some embodiments, the target alloy has a composition and material properties similar to commonly produced commercially available aluminum alloys.

[0034] The term "foil" refers to a metal sheet used to form each layer in a layer stack. The foil may include one or more sublayers, at least one of which, and optionally a number of intermediate layers, includes a different metal alloy than the first layer. In some embodiments, the foil has a linear thickness between 10 μm and 10 mm. In some embodiments, the foil has a linear thickness between 25 μm and 1000 μm. In further embodiments, the foil may have a linear thickness between 50 μm and 500 μm. In some embodiments, the foil may be patterned to correspond to the design of the object and its supporting structure. In some embodiments, the foil can include at least one of Al, Sb, Ba, Be, Bi, B, Cd, Ca, C, Cr, Co, Cu, Gd, Ga, H, Fe, Pb, Li, Mg, Mn, Mo, Nd, Ni, Nb, N, O, Pd, P, K, S, Si, Ag, Na, Sr, S, Ta, Th, Sn, Ti, V, Y, Zn, Zr, or a rare earth metal. In some embodiments, the foil can include at least one of aluminum, magnesium, titanium, an aluminum alloy, a magnesium alloy, or a titanium alloy.

[0035] The term "core" or "core layer" refers to the foil or portion of the foil that comprises the majority of the layer stack. The composition of the alloy used in the core layer material is described in terms of the primary alloying elements.

[0036] The term "interlayer" refers to a foil or portion of a foil that allows adjacent foils to be joined. In some embodiments, the interlayer may be applied to at least one side of the core layer, on the outside of the foil. In some embodiments, the thickness of the interlayer is less than the thickness of the core layer. The composition of the alloy used in the interlayer is described in terms of the primary alloying elements.

[0037] The term "clad layer" or "clad" refers to an interlayer material that is bonded to a core layer prior to the beginning of the bonding and homogenization process. In some embodiments, the thin interlayer of one composite roll bonded to the core layer is described as a "clad foil."

[0038] A "layer stack" refers to at least two foils. In some embodiments, a single foil can include at least one support region and at least one object region. "Support" refers to non-object components of the foils that, when joined together, form a holder or jig that fits onto the outside of an object and can be used after subsequent processing. This holder or jig formed as a combination of multiple support regions is sometimes referred to as a "support area." The combination of object regions is sometimes referred to as an "object area." The process of combining is sometimes referred to as "bonding."

[0039] The term "aluminum" refers to any material containing aluminum. For example, a material containing aluminum can refer to pure molecular aluminum, aluminum pure to standard industrial grades, an alloy of aluminum with at least one other element, or any combination thereof. When an alloy contains a specific metal, such as aluminum, at least some of the alloy compositions are of the same specific metal. Any secondary alloying elements present are listed below.

[0040] Some embodiments herein relate to methods for producing metal objects from constituent metal layers with comparable mechanical properties. In some embodiments, these methods avoid the use of adhesives between the layers and instead form the object using high-strength metallurgical bonds between the constituent layers. For aluminum parts, some embodiments may use joining methods such as diffusion bonding, transient liquid phase diffusion bonding, and / or brazing. Specific configurations of materials, such as alloy composition, alloy structures including composites of two or more sublayers with different compositions, and process conditions, such as applied temperature and pressure, can result in strong metallurgical bonds in shorter, more robust processes useful for producing aluminum parts.

[0041] In some embodiments, the manufacturing methods described herein first receive the desired alloy composition for the object. These embodiments then apply heat to a foil stack including at least one core layer and at least one intermediate layer to homogenize the composition of the stack. The resulting product is a homogenized object with the desired alloy composition. The foils in the stack can be selected, for example, so that one layer has an excess of one element and an adjacent layer has a deficiency of the same element, so that the resulting object has the desired ratio of elements. This can also be true for multiple elements that form the desired composition for the object.

[0042] 1 illustrates a cross-sectional view of a metal laminate object 100 produced according to one embodiment. In some embodiments, object 100 may be produced on a print bed 105. In some embodiments, a foil 110 may be deposited on print bed 105. In some embodiments, multiple foils may be either deposited directly on a first foil 110 or may be subsequently added on top of the first foil 110.

[0043] Figure 2 illustrates a triangle view 205 and an object view 210 of the metal laminate object of Figure 1 according to one embodiment. The object may be surrounded by support areas 215, 220, which may be removed after object area 225 is formed and finishing of the metal laminate object is complete, as described in more detail below.

[0044] 3 illustrates a cross section of individual foils 305, 315, 325, according to one embodiment. In some embodiments, at least one foil (not shown) in the stack of foils may consist entirely of core layer 310. In some embodiments, foil 315 may include core layer 330 and a separate intermediate layer 335 on one surface. In some embodiments, intermediate layer 335 may be present on top of core layer 330. In some embodiments, intermediate layer 335 may be present on the bottom of core layer 330. In some embodiments, foil 325 may include core layer 350 and two intermediate layers 335 on either side of the foil.

[0045] In some embodiments, the core layer may comprise aluminum, hi some embodiments, the core layer may be an aluminum alloy.

[0046] In some embodiments, the intermediate layer may comprise a metal or alloy having a lower melting point than the core layer. In some embodiments, the intermediate layer material may comprise at least one of aluminum, copper, chromium, iron, magnesium, manganese, silicon, titanium, and zinc. In some embodiments, the metal elements may be present in several different combinations, with each composition selected for a specific set of properties compatible with the joining method, such as surface oxidation resistance on the core layer, surface oxide breakdown, optimal melting temperature, and liquid-state properties such as wettability. In some embodiments, the two intermediate layers may comprise different materials. In some embodiments, the two intermediate layers may be identical.

[0047] In some embodiments, the thickness of the intermediate layer may be 1-50% of the thickness of the core layer. In some embodiments, the thickness of the intermediate layer may be 0-5% of the thickness of the core layer 330. In some embodiments, the thickness of the intermediate layer in the case of a single clad foil may be 1-25% of the thickness of the core layer 330. In some embodiments, the thickness of the intermediate layer in the case of a double clad foil may be 2-50% of the thickness of the core layer.

[0048] In some embodiments, the thickness of the intermediate layer is less than the thickness of the core layer. In some embodiments, the total thickness of the foil is greater than 25 μm. In other embodiments, the total thickness of the foil is less than 1000 μm. In some embodiments, the thicknesses of the core layer and intermediate layer, and the ratio of the core layer thickness to the intermediate layer thickness, can vary and be optimized for a particular bonding method.

[0049] In some embodiments, the particular composition of the intermediate layer is selected so that the intermediate layer material melts at a lower temperature than the core layer. In some embodiments, the intermediate layer material is selected to minimize the melting temperature. In some embodiments, the melting temperature of the intermediate layer material may be greater than 500°C and less than 590°C. In some embodiments, the melting temperature of the intermediate layer material may be less than 500°C. In a different subset of these embodiments, the melting temperature of the intermediate layer material may be less than 490°C. In some embodiments, the ratio of the intermediate layer material to the core layer material and their compositions are selected so that the final mechanical properties of the object are those of a desired composition. In some embodiments, if the components of the intermediate layer are only a small portion of the overall foil, the desired composition may be within the tolerance of the core material composition.

[0050] In some embodiments, the composition of the foils in the stack is selected so that, once heated, the finished object will have a desired composition. For example, if the finished object is to have a desired composition compatible with a particular alloy, the individual sheets may each have excesses or deficiencies of various elements, but when heated, the finished article will have a substantially uniform composition that matches the desired composition.

[0051] For example, Figure 4A illustrates a foil 400a according to one embodiment. The foil 400a includes a single core layer 402a clad on one side with an intermediate layer 404a. Figure 4B illustrates a foil 400b according to another embodiment. The foil 400b includes a single core layer 402b clad on both sides with an intermediate layer 404b.

[0052] The core layers 402a and 402b may comprise a majority of aluminum or magnesium, and additional alloying elements may be present, such as, but not limited to, copper, silicon, zinc, or other materials previously discussed.

[0053] Intermediate layers 404a and 404b may include some combination of aluminum, copper, magnesium, silicon, and zinc, or other materials previously discussed. Intermediate layers 404a and 404b may alternatively include a uniform layer of any single element in the above list.

[0054] In some embodiments, the intermediate layer comprises between 1 and 50% of the total foil thickness. In some embodiments, such as those in which the intermediate layer comprises a single element, the intermediate layer may comprise a thin layer that is less than 5% of the total foil thickness.

[0055] The specific composition of the core layer or intermediate layer can match that of a commercially available aluminum alloy. For example, the core layer may include 2024, 5182, 6061, or another alloy. Custom alloys that largely match the commercially available alloy composition but have either higher or lower concentrations of one or more elements present in the intermediate layer may also be used. The intermediate layer may include 2024, 4004, 5182, 6061, 7075, or another commercially available aluminum alloy. The intermediate layer may also include a custom alloy that matches the commercially available alloy composition but may additionally have higher or lower concentrations of one or more elements.

[0056] The compositions of the core layer and intermediate layer may vary from one another, for example, in some embodiments, an element present in excess in the intermediate layer may be present in a lower concentration in the core layer to achieve a desired composition after homogenization.

[0057] Alternatively, elements present in excess in the core layer may be present in lower concentrations in the intermediate layer to achieve the desired composition after homogenization. The relative thicknesses of the layers may also be selected to match the average composition of the alloy to 2024, 6061, 7075, or another desired composition.

[0058] As another example, the core layer may include a magnesium alloy with a high melting point. The intermediate layer may include a low melting point magnesium alloy and a custom alloy with a high or low concentration of alloying elements. In some embodiments, the intermediate layer may include elements that lower the melting point of magnesium.

[0059] In operation, a user or system can subject a part to a heated environment, such as a furnace. The furnace can apply heat to the part to raise the temperature of the part and maintain the temperature of the part at a particular temperature or range of temperatures for a period of time. Specifically, techniques according to embodiments herein can include a bonding stage in which layers are heated and bonded together, followed by a homogenization stage in which the bonded layers are heated to produce a homogenized product. The homogenized product can then be quenched.

[0060] In some embodiments, the bonded parts may be transferred to a separate furnace processing unit where a homogenization step is performed. The parts may be moved, for example, with a support structure. In other embodiments, a chamber may protect the parts during transfer to protect the surfaces from oxidation. In some embodiments, the chamber may be under vacuum or may be a shielded gas chamber in which an inert or non-oxidizing gas is present around the parts. In some embodiments, these steps may further include a polishing step, in which the parts may be polished or otherwise modified before or after the homogenization process.

[0061] During the heating stage, the furnace may apply heat to the part to raise the temperature of the part to the processing temperature, i.e., heat may be applied to the part until the temperature of the part reaches the processing temperature.

[0062] In some embodiments, the processing temperature is below the solidus temperature of the intermediate layer and the core layer. For example, the furnace may be configured to set the processing temperature between 5°C and 100°C below the solidus temperature of the intermediate layer.

[0063] In some embodiments, the part can be in a hot press during the homogenization process to increase or improve heat transfer to the part. Better controlled heat transfer allows for more even and sustained heating of the part during the processing stage, allowing for finer control of the rate at which elements diffuse into the part without melting the part. This improves the diffusion rate and reduces the chance of defect formation in the part.

[0064] 4C illustrates a foil or part 406 produced by stacking foils, such as foil 400a or 400b. For example, part 406 appears to include multiple core layers 402c and multiple intermediate layers 404c.

[0065] During the homogenization process, a foil such as foils 400a-c is maintained at a processing temperature for a period of time to allow interdiffusion of elements in the intermediate layer and core layer, thereby forming a substantially uniform composition in both regions. This interdiffusion process involves two simultaneous phenomena: elements present in the intermediate layer diffuse into the core layer region, and elements present in the core layer diffuse into the intermediate layer region. Because the thickness of the core layer can be at least several times thicker than the thickness of the intermediate layer, the slowest-diffusing elements are constituents present in at least one of the core layer and intermediate layer that diffuse into the complementary layer.

[0066] Furthermore, elements with lower diffusion coefficients will diffuse more slowly than elements with higher diffusion coefficients at the same concentration gradient, temperature, and other environmental conditions. Therefore, the slowest-diffusing element is the element with the lowest diffusion coefficient. Once the slowest-diffusing element is present in both the core and intermediate layers, the foil can be considered homogenized, and the peak composition of the slowest-diffusing element is within the standard tolerance for the alloy composition in published standards, such as specified TEAL sheet.

[0067] 4D illustrates a part 408 produced from the homogenization process, according to one embodiment. As can be seen in FIG. 4D, the part 408 has at least a portion that is completely homogenized and uniform in composition.

[0068] 5 illustrates a concentration profile 500 of the interface surrounding the intermediate layer 502 and bordering the two core layers 504 as a function of time during the homogenization process. In this example, there are alloying elements initially (i.e., before the homogenization process begins) that are present in the intermediate layer 502 but not in either of the core layers 504.

[0069] Series 506 represents the initial concentration of this alloying element before the homogenization process begins. As can be seen in Figure 5, the concentration of this alloying element is high in intermediate layer 502 but zero in core layer 504. That is, the composition of core layer 504 does not contain any alloying element before the homogenization process begins.

[0070] The three progressive series 508, 510, and 512 represent the concentrations of alloy elements at various points in time throughout the homogenization process. Series 508 represents the alloy element concentration at time t1, series 510 represents the alloy element concentration at time t2, series 512 represents the alloy element concentration at time t3, and t1 < t2 < t3. From t1 to t3, as the composition of the alloy elements in the intermediate layer 502 diffuses from the region previously occupied by the intermediate layer 502, it decreases. When this occurs, the composition of the alloy elements in the core layer 504 increases. Series 514 represents the concentration of alloy elements at the end of the homogenization process. As seen in profile 500, the concentration of alloy elements decreases in the intermediate layer 502 and increases in the core layer 504.

[0071] Figure 6 illustrates an operation profile 600 for a homogenization process as a function of time according to one embodiment. The homogenization process associated with profile 600 in Figure 6 may be similar to the process described in connection with Figure 5, for example.

[0072] The temperature 602 is initially at room temperature or ambient temperature 604 before starting the homogenization process. The temperature 602 can be heated to a temperature lower than the solidus temperature 606 of the intermediate layer. The solidus temperature 606 of the intermediate layer is lower than the solidus temperature 608 of the core layer.

[0073] The time required for the homogenization process is partly determined by the thicknesses of the core layer and the intermediate layer. For example, the time required for the homogenization process increases or decreases according to the layer thickness. Specifically, a foil with a thinner intermediate layer requires less time for homogenization.

[0074] Similarly, the rate at which the diffusing elements move increases with an increase in temperature. Therefore, the time required for the homogenization process is also a function of temperature and decreases as the processing temperature increases.

[0075] The temperature 602 may be reduced back to room or ambient temperature 604 after a period of time sufficient to facilitate the equalization process. The cooling step may include quenching the part in water, oil or another fluid, using a fan, or otherwise blowing air onto the part to cool it, natural cooling, etc.

[0076] 7 illustrates a flow diagram of a method 700 for manufacturing an object, according to one embodiment. A homogenized part produced from two or more different constituent alloys may exhibit mechanical properties superior to either of the constituent alloys. In some cases, the alloy composition selected for the constituent layers may have weaker mechanical properties than the final homogenized part.

[0077] For example, the core and intermediate layers may alternatively contain higher percentages of magnesium and silicon than the 2:1 stoichiometric ratio. This ratio would normally produce a weak, soft material. However, the overall percentages of magnesium and silicon are present in a ratio such that the homogenized part is a high-strength, hardened 6000 series alloy with a magnesium-to-silicon ratio that satisfies the desired alloy composition. This allows the alloy to have processing conditions, such as melting temperature, fine-tuned by the selective presence of magnesium and silicon without the negative consequences of an excess of one of these elements in the final homogenized part.

[0078] Step 702 includes receiving a desired alloy composition for the object, which may be a copper-rich aluminum alloy in the 2000 series, a silicon-rich aluminum alloy in the 4000 series, a magnesium-rich aluminum alloy in the 5000 series, a magnesium- and silicon-rich aluminum alloy in the 6000 series, a zinc-rich aluminum alloy in the 7000 series, etc.

[0079] Step 704 includes depositing multiple foils in a stack to form the object. The type of foils deposited in the stack as part of step 704 may depend on the desired alloy composition specified in step 702.

[0080] For example, if the desired alloy composition is a 6000 series aluminum alloy, a core layer of a 6000 series alloy and an intermediate layer of a 2000 series alloy may be used, where copper from the copper-rich 2000 series intermediate layer diffuses into the 6000 series alloy core layer to produce a low copper 6000 series alloy, such as 6061, which is a high strength machinable alloy.

[0081] If the desired alloy composition is a 5000 series magnesium-rich aluminum alloy, a core layer of a 1000, 3000, or 1000 series alloy and an intermediate layer of a 5000 series alloy may be used. If the desired alloy composition is a 4000 series silicon-rich aluminum alloy, a core layer of a 6000 series alloy and an intermediate layer of a 4000 series alloy may be used. If the desired alloy composition is a 7000 series zinc-rich aluminum alloy, a core layer of at least one of a 2000, 5000, 6000, or 7000 series alloy and an intermediate layer of a 7000 series alloy may be used.

[0082] In some embodiments, when the homogenizing component is an X000 series aluminum alloy, both the intermediate layer and the core layer may be the same X000 series alloy. In other embodiments, when the homogenizing component is an X000 series aluminum alloy, both the intermediate layer and the core layer may be custom alloys that match the X000 series composition, except that either the core layer or the intermediate layer has an excess of at least one element and the complementary alloy has a deficiency of at least one of the same elements.

[0083] In some embodiments, the composition of the individual foil layers in the stack can be selected so that when spread using the processes described above, the result is an object with a uniform composition that matches a desired composition that is not the same as the composition of the constituent foils. The table below identifies some alloys and the constituent foils that can be used to achieve those alloys. [Table 1] [Table 2] [Table 3] [Table 4] [Table 5] [Table 6] [Table 7] [Table 8] [Table 9] [Table 10]

[0084] Each table specifies various compositions for the core and cladding layers (i.e., intermediate layers), while the table labels specify the desired alloy series. The entry numbers correspond to the weight fraction of each of the major alloying elements, with the remainder being aluminum (Al). These compositions above are merely exemplary, and other compositions may be realized according to embodiments herein.

[0085] The foils may be clad on one or both sides, and the total thickness of the foils may be between 25 μm and 1,000 μm. The thickness of the core layer is typically greater than the thickness of the intermediate layer. In some embodiments, the foils are "all-core" or "all-clad" for each instance. In these embodiments, the foils may be alternated to produce a striped layer structure of alternating core and clad layers, similar to that produced by a stack of clad foils.

[0086] Step 706 includes applying heat to the stack at a first temperature to bond the foils together. The stack can include multiple layers of foil. Each layer can include, for example, an aluminum alloy, a magnesium alloy, or a titanium alloy. The alloy material can be aluminum, chromium, copper, lithium, magnesium, manganese, titanium, nickel, silicon, or zinc. The first temperature required to bond the foils together can depend on the materials used.

[0087] Step 708 includes applying heat to the stack at a second temperature to homogenize the composition of the stack. As previously discussed, the stack (e.g., foils) can be heated to achieve a desired level of interdiffusion. In some embodiments, the second temperature is below the melting point of the foils. In some embodiments, the second temperature can be about the solidus temperature of the foils or the desired alloy composition. In some embodiments, the second temperature can be the same as the first temperature.

[0088] Step 710 is optional and involves quenching the laminate after homogenization. This quenching step may occur in the same processing unit where the homogenization step occurs, or may occur at a separate processing unit from where the homogenization step occurs. The optional quenching step may be used depending on the desired alloy properties.

[0089] 8 illustrates an additive manufacturing system 800 comprising two plates 805′, 805″ (collectively, “805”) configured to apply at least one of heat and pressure to a layer stack 815 to bond foils 810, according to one embodiment. Some embodiments may use at least one bonding method to bond at least two foils 810 in the layer stack 815.

[0090] In some embodiments, platen 805 may be at least one of a pressure plate or a heating plate. In some embodiments, platen 805 may be configured to apply at least one of heat or pressure to opposite sides of layer stack 815. In some embodiments, applying at least one of heat or pressure raises the temperature of layer stack 815 to a temperature below the melting temperature of the core layer of foil 810, such that at least one of heat or pressure bonds a first foil to a second foil in layer stack 815.

[0091] In some embodiments, plate 805 may apply even pressure to layer stack 815 to bond object region 820. In some embodiments, layer stack 815 may include a complete enclosure of object region 820. The complete enclosure may include at least two support regions 825, 830, such that object region 820 is completely surrounded by support regions 825, 830.

[0092] In some embodiments, support regions 825, 830 are configured to conduct at least one of heat or pressure from plate 805 through layer stack 815. Such conduction of heat or pressure facilitates bonding of foil 810 to form bonded object region 820. In some embodiments, plate 805 applies at least one of heat or pressure to support regions 825, 830, which in turn conducts at least one of heat or pressure to object region 820. In some embodiments, support regions 825, 830 may have flat surfaces such that plate 805 can apply at least one of pressure or heat evenly across the entire surface. In some embodiments, the support region is a single support region surrounding object region 820, which can be used to create a negative of the object. In some embodiments, the bonding process of object region 820 may be performed in an oxidizing atmosphere, such as air. In some embodiments, the bonding process of foil 810 may be enclosed in a vacuum or inert gas chamber.

[0093] In some embodiments, the system may use at least one of diffusion bonding, transient liquid diffusion bonding, and / or brazing, hi some embodiments, the alloy composition and processing conditions are optimized for efficient diffusion bonding.

[0094] 9 schematically illustrates a method 900 for additive manufacturing of an object by diffusion bonding, according to one embodiment. Method 900 includes applying heat to a stack of foils to raise the foils to a bonding temperature (step 905). In some embodiments, the bonding temperature may be below the melting temperature of the core layer of foils and high enough to promote diffusion and bonding between adjacent foils. In some embodiments, the bonding temperature may be below the temperature of the intermediate layer of foils. In some embodiments, at least one plate may apply heat to the foils.

[0095] In some embodiments, the foil stack may be brought up to a bonding temperature and optionally pressure applied (step 915), and the bonding temperature and optionally pressure may be maintained (step 925) until elements from adjacent core layers diffuse into each other, bonding the foil stack to the object region (step 930).

[0096] In some embodiments, the method may include a sequential diffusion bonding process. In a sequential diffusion bonding process, the method may include adding a foil to the object or portion of the object at a bonding temperature (step 920). In some embodiments, the bonding temperature may be below the melting temperature of the core layer material. Alternatively, the foil may be added to a cold foil stack, or the stack with additional foil may be brought to the bonding temperature. In some embodiments, the foil is added to an already heated stack, and pressure is applied to the stack. In some embodiments, after pressure is applied, the pressure is released and another foil is added (step 920).

[0097] In some embodiments, the temperature can promote diffusion and bonding between elements of the added foil core layer and the object, thereby enabling the bonding process.

[0098] In some embodiments, the object or at least one of its components can act as a heat sink. In some embodiments, the heat sink can create a temperature gradient across the object to selectively promote diffusion bonding in some regions of the object. In some embodiments, the diffusion process can be repeated until the object is complete.

[0099] 10 schematically illustrates a method 1000 for additive manufacturing of objects by transient liquid phase (TLP) diffusion bonding, according to one embodiment. Some embodiments can optimize alloy compositions and processing conditions for efficient bonding by transient liquid phase (TLP) diffusion bonding in an oxidizing or non-oxidizing atmosphere, or under vacuum.

[0100] In some embodiments, the core material is aluminum or an aluminum alloy. In some embodiments, the core material may include at least one of aluminum, magnesium, titanium, copper, silicon, or zinc. The alloying element may include at least one of magnesium or zinc. In some embodiments, the clad interlayer may include at least one of an aluminum-magnesium alloy, a magnesium-zinc alloy, an alloy of at least two of aluminum, copper, magnesium, silicon, or zinc, or any combination thereof. In some embodiments, at least one of the alloying elements of these interlayers may act as an oxide getter, preferentially binding oxygen at a rate greater than aluminum.

[0101] In some embodiments, the aluminum alloy foil may comprise between 20% and 100% aluminum. In some embodiments, the aluminum alloy foil may comprise at least one of Sb, Ba, Be, Bi, B, Cd, Ca, C, Cr, Co, Cu, Ga, Fe, Pb, Li, Mg, Mn, Ni, O, P, K, Sc, Si, Ag, Na, Sr, Sn, Ti, V, Zn, or Zr. In some embodiments, the aluminum alloy foil may comprise more than 50% Cu. In some embodiments, the aluminum alloy foil may comprise more than 40% Fe. In some embodiments, the aluminum alloy foil may comprise more than 40% Mg. In some embodiments, the aluminum alloy foil may comprise more than 40% Ni. In some embodiments, the aluminum alloy foil may comprise more than 40% Zn. In some embodiments, the aluminum alloy foil may comprise more than 60% Si.

[0102] In some embodiments, the magnesium alloy foil may include between 45% and 100% magnesium. In some embodiments, the magnesium alloy foil may include at least one of Al, Be, Ca, Ch, Cu, Gd, Fe, Li, Mn, Nd, Ni, Si, Ag, Th, Y, Zn, Zr, or a rare earth metal. In some embodiments, the magnesium alloy foil may include more than 40% Al.

[0103] In some embodiments, the titanium alloy foil can include between 70% and 100% titanium. In some embodiments, the titanium alloy foil can include at least one of Al, B, C, Cr, Cu, H, Fe, Mn, Mo, Ni, Nb, N, O, Pd, Si, S, Ta, Sn, V, Y, or Zr.

[0104] In some embodiments, the melting temperature of the intermediate layer may be at least 10°C lower than the melting temperature of the core layer. The melting temperature of the intermediate layer may be minimized to reduce energy costs and mechanical complexity of processing. In some embodiments, the melting temperature of the intermediate layer may be less than 500°C.

[0105] In some embodiments, the total foil thickness is generally between 25 μm and 1000 μm. Each intermediate layer may be up to 50% of the thickness of the core material and may be between 1 μm and 50 μm thick. The intermediate layer material may be deposited on either one or both sides of the core material to form a single foil.

[0106] In some embodiments, the method may use a diffusible element including at least one of Cu, Mg, Zn, or Si. In some embodiments, the intermediate layer may include at least 0.2% Cu. In some embodiments, the diffusible element may include at least 1% Cu. In some embodiments, the diffusible element may include at least 2% Cu. In some embodiments, the diffusible element may include up to 4% Cu. In some embodiments, the diffusible element may include up to 5% Cu. In some embodiments, the diffusible element may include up to 6% Cu. In some embodiments, the diffusible element may include up to 6.3% Cu.

[0107] In some embodiments, the method includes raising the foil stack up to a bonding temperature (step 1005), which is higher than the melting temperature of the intermediate layer but lower than the melting temperature of the core layer of the constituent foils.

[0108] In some embodiments, the method may include compressing the foil stack by applying pressure (step 1010). In some embodiments, the pressure may be between approximately 0.1 and 100 MPa.

[0109] In some embodiments, application of at least one of temperature or pressure may melt the intermediate layer and increase the rate of diffusion of elements from the core layer into the intermediate layer, and vice versa (step 1015). In some embodiments, the applied pressure may promote intermixing of elements between the core and intermediate layers of adjacent foils.

[0110] In some embodiments, as elements of the intermediate and core layers interdiffuse, the average composition of the laminated foil changes to resemble the final average composition of the body, and the melting temperature increases corresponding to the composition change, hi some embodiments, new bonds are formed between the metallic components.

[0111] In some embodiments, this process can be performed sequentially. In a sequential process, a foil can be applied to the parts at a bonding temperature that is above the melting temperature of the interlayer material, or a new foil can be applied to a cold laminate, which is then brought up to the bonding temperature. In some embodiments, the applied interlayer of foil can be melted (step 1015) to continue the bonding process.

[0112] In some embodiments, previously deposited layers are unaffected by this process because the constituent interlayers of the previously deposited layers have already interdiffused with the core layer and bonded such that the parts do not melt at the applied bonding temperatures.

[0113] 11 shows a schematic of a method 1100 for additive manufacturing of an object by brazing, according to one embodiment. In some embodiments, brazing is used to optimize alloy composition and processing conditions for joining.

[0114] In some embodiments, the method includes depositing a first foil (step 1105). In some embodiments, the first foil may be deposited on a print bed. In some embodiments, the first foil may be deposited on a foil. In some embodiments, the method further includes depositing a second foil (step 1115). In some embodiments, the foil may include at least one intermediate layer and at least one core layer.

[0115] In some embodiments, the foil may be brought up to a bonding temperature (step 1120), which in some embodiments is above the melting temperature of the intermediate layer, but below the melting temperature of the core layer of the foil.

[0116] In some embodiments, the foil may be maintained at this bonding temperature for a fixed period of time (step 1125). In some embodiments, maintaining the foil at the bonding temperature may cause the intermediate layer to melt, which increases the rate of diffusion of elements from the core layer into the intermediate layer and correspondingly increases the rate of diffusion of elements from the intermediate layer into the core layer.

[0117] This process causes the formation of metallurgical bonds between adjacently stacked foils to form an object (step 1130).

[0118] In some embodiments, the brazing process may be performed sequentially. In a sequential brazing process, foils may be added to a subassembly or object comprising several joining foils. In some embodiments, additional liquid flux may be applied to the void space between the additional foils and the object.

[0119] In some embodiments, the added foil and component may be brought up to a bonding temperature that is higher than the melting temperature of the intermediate layer of the added foil, but lower than the melting temperature of the core layer of the added foil and lower than the melting temperature of the alloy that makes up the component (step 1120).

[0120] In some embodiments, the applied foil and component may be maintained at this bonding temperature for a fixed period of time (step 1125), which causes the interlayer of the applied foil to melt and the bonding process described above to occur.

[0121] In some embodiments, previously deposited layers may be unaffected by this process because the constituent interlayers of the previously deposited layers have already melted and interdiffused with the core layer and bonded such that the bodies do not melt at the applied bonding temperature.

[0122] In some embodiments, the alloy compositions of the core and intermediate layers may be used in other form factors, such as core-structured powders or core-structured wires, or a combination of two powder compositions, which may then be joined and, when diffused using the processes described above, the result is an object with a uniform composition that matches a desired composition that is not the same as the composition of the constituent inputs.

[0123] The methods, systems, and devices discussed above are examples. Various configurations may omit, substitute, or add various steps or components, as appropriate. For example, in alternative configurations, the methods may be performed in an order different from that described, and various such steps may be added, omitted, or combined. Similarly, features described with respect to particular configurations may be combined in various other configurations. Different aspects and elements of the configurations may be combined in a similar manner. Similarly, technology evolves, and therefore, many of the elements are examples and do not limit the scope of the disclosure or claims.

[0124] For example, embodiments of the present disclosure have been described above with reference to block diagrams and / or operational illustrations of methods, systems, and computer program products according to embodiments of the present disclosure. The functions / acts specified in the blocks may occur out of the order shown in any flow diagram. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, and the blocks may sometimes be executed in the reverse order, depending on the functions / acts involved. Additionally or alternatively, not all of the blocks shown in any flow diagram need to be implemented and / or performed. For example, if a given flow diagram has five blocks containing functions / acts, only three of the five blocks may be implemented and / or performed. In this example, any three of the five blocks may be implemented and / or performed.

[0125] A statement that a value exceeds (or is greater than) a first threshold is equivalent to a statement that the value meets or exceeds a second threshold that is slightly greater than the first threshold, e.g., the second threshold is a value higher than the first threshold at the resolution of the relevant system. A statement that a value is less than (or is within) a first threshold is equivalent to a statement that the value is less than or equal to a second threshold that is slightly less than the first threshold, e.g., the second threshold is a value lower than the first threshold at the resolution of the relevant system.

[0126] Specific details are set forth in the description to provide a thorough understanding of example configurations (including implementations). However, configurations may be practiced without these specific details. For example, well-known circuits, processes, algorithms, structures, and techniques are shown without unnecessary detail to avoid obscuring the configurations. This description merely presents example configurations and does not limit the scope, applicability, or configuration of the claims. Rather, the foregoing description of the configurations provides one of ordinary skill in the art with an enabling description for practicing the described techniques. Various changes can be made in the function and arrangement of elements without departing from the spirit or scope of the present disclosure.

Claims

1. a core comprising the balance Al, and between 0.2 and 0.4 wt. % Si, between 0.15 and 0.4 wt. % Cu, between 0.8 and 1.2 wt. % Mg, and between 0.04 and 0.35 wt. % Cr; and The remaining amount of Al, and a clad containing between 1.5 and 4.5 wt.% Si, between 0.15 and 0.4 wt.% Cu, between 0.4 and 1.2 wt.% Mg, and between 0.04 and 0.35 wt.% Cr. Including, clad foil.

2. 2. The clad foil of claim 1, wherein the trace elements in the core and clad compositions comprise between 0 and 0.3 wt. % Fe, between 0 and 0.1 wt. % Mn, between 0 and 0.25 wt. % Zn, and between 0 and 0.15 wt. % Ti, with any other element being less than 0.05 wt. % and the sum of all other elements being less than 0.15 wt. %.

3. 10. The clad foil of claim 1, wherein each foil is between 25 μm and 1000 μm thick.

4. The clad foil of claim 1 , wherein the core is a first layer of the foil and the clad is a second layer of the foil.

5. 10. The clad foil of claim 1, wherein a first layer forms a first cladding of the foil, a second layer forms the core of the foil, and a third layer forms a second cladding of the foil.

6. The clad foil of claim 1, wherein the cladding is between 8% and 45% of the total thickness of the clad foil.

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