Uniform foil homogenization for light alloy metal parts

Abstract

A method for manufacturing an object, the method comprising the steps of receiving a desired alloy composition for the object, depositing 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 together, and applying heat to the stack at a second temperature to homogenize the composition of the stack. The homogenized stack has a desired alloy composition. A method for manufacturing an object, the method comprising the steps of receiving a desired alloy composition for the object, depositing a plurality of foils having at least two constituent compositions in a stack to form the object, applying heat to the stack at a first temperature to bond the plurality of foils together, and applying heat to the stack at a second temperature to homogenize the composition of the stack, the homogenized stack having the desired alloy composition.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of and priority to U.S. Provisional Patent Applications Nos. 63 / 131,285 and 63 / 257,091, filed December 28, 2020 and October 18, 2021, respectively, 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 by reference herein as if set forth in their entirety herein.

[0002] Technical Field The embodiments described herein relate to methods and systems for manufacturing objects, and more particularly, but not exclusively, to methods and systems for manufacturing objects 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 multiple foils of at least two layers of alloys and bonding the foils together to produce 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 be equivalent to 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, depositing 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 a 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 application of heat at a first temperature occurs in a first processing unit and the application of heat at a 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 description of the drawings]

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

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

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

[0021] [Figure 4] 4A-D illustrate various configurations of foils according to several embodiments.

[0022] [Diagram 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 diagrammatically a method for additive manufacturing of an object by brazing according to one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Detailed Description Various embodiments are described more fully below with reference to the accompanying drawings, which form a part hereof and which show certain exemplary embodiments. However, the concepts of the present disclosure may be implemented in many different forms and should not be construed as being limited to the embodiments described 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, a system or a device. Thus, the embodiments may take the form of a hardware implementation, a fully software implementation, or an implementation combining software and hardware aspects. Thus, 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. The appearances of the phrase "in one embodiment" in various places in the specification do not necessarily all refer to the same embodiment.

[0031] Moreover, the language used herein has been selected primarily for ease of reading and instructional purposes, and may not have been selected 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 a method used to homogenize the composition of lightweight alloyed laminated components. These laminated components may be the product of a LOM process. In some embodiments, the components may include a plurality of foils bonded together by a process, each foil comprising at least one core layer and at least one intermediate layer. In other embodiments, the components may include a plurality of foils bonded together by a process, the plurality of foils including alternating foils of uniform core layers and uniform intermediate layers. In some embodiments, the method comprises applying heat for a predetermined processing time to promote solid-state diffusion of alloying elements throughout a majority of the component. In some embodiments, the solid-state diffusion homogenizes the composition of alloying elements throughout a majority of the component to improve the mechanical properties of the LOM produced components. In embodiments of the method, no significant amount of material is added to the component.

[0033] In some embodiments, both the composition and relative ratios of the constituent layers that make up the foil are selected so that the fully homogenized part has an average composition that corresponds 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 stack of layers. The foil may include one or more sublayers, of which at least one layer and optionally a number of intermediate layers include a different metal alloy than the first layer. In some embodiments, the foil has a thickness in one dimension between 10 μm and 10 mm. In some embodiments, the foil has a thickness in one dimension between 25 μm and 1000 μm. In further embodiments, the foil may have a thickness in one dimension between 50 μm and 500 μm. In some embodiments, the foil may be patterned to correspond to the design of the object and its support 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 rare earth metals. 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 stack of layers. The composition of the alloys 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, at the outer surface of the foil. In some embodiments, the thickness of the interlayer is less than the thickness of the core layer. The composition of the alloys used in the interlayer is described in terms of the primary alloying elements.

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

[0038] A "stack of layers" 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. A "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 further processing. This holder or jig formed as a combination of multiple support regions may be referred to as a "support area." The combination of object regions may be referred to as an "object area." The process of combining may be referred to as "bonding."

[0039] The term "aluminum" refers to any material that contains aluminum. For example, a material that contains aluminum can refer to a material that is made of 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 a plurality of the alloy compositions are of the same specific metal. 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 layers, and instead use high-strength metallurgical bonds between the constituent layers to form the object. For aluminum parts, some embodiments may use bonding methods such as diffusion bonding, transient liquid phase diffusion bonding, and / or brazing. The specific configuration of materials, such as alloy composition, alloy structures, including composites of two or more sublayers with different compositions, and processing conditions, such as applied temperature and pressure, may 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 stack of foils 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, such that one layer has an excess of one element and an adjacent layer has a lack 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 side cross-sectional view of a metal laminate object 100 produced according to one embodiment. In some embodiments, the object 100 may be produced on a print bed 105. In some embodiments, a foil 110 may be deposited on the surface of the print bed 105. In some embodiments, multiple foils may be either deposited directly on the surface of the first foil 110 or may be later added on top of the first foil 110.

[0043] Figure 2 illustrates a triangular 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 that may be removed after object area 225 is formed and finishing of the metal laminate object is completed, 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 the 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 being selected for a particular set of properties that are compatible with its joining method, such as surface oxidation resistance on the core layer, surface oxide destruction, liquid state properties such as optimum melting temperature and 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 thickness of the core layer to the thickness of the intermediate layer, are varied and optimized for a particular bonding method.

[0049] In some embodiments, the particular composition of the intermediate layer is selected such 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 different subsets 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 such that the final mechanical properties of the object are those of the desired composition. In some embodiments, the desired composition may be within the tolerance of the composition of the core material if the components of the intermediate layer are only a small portion of the overall foil.

[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 that is clad on one surface with an intermediate layer 404a. Figure 4B illustrates a foil 400b according to another embodiment. The foil 400b includes a single core layer 402b that is clad on both surfaces with an intermediate layer 404b.

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

[0053] The intermediate layers 404a and 404b may include some combination of aluminum, copper, magnesium, silicon, and zinc, or other materials previously discussed. The 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 1-50% 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 the 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 a higher or lower concentration 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 also have a higher or lower concentration of one or more elements.

[0056] The compositions of the core layer and the 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 layers 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 an oven. The oven can apply heat to the part, elevating the part and maintaining the temperature of the part at a certain temperature or range of temperatures for a period of time. In particular, 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 may then be quenched.

[0060] In some embodiments, the bonded parts may be transferred to a separate furnace processing unit, which performs the homogenization step. The parts may be moved, for example, together with a support structure. In other embodiments, a chamber may protect the parts during the transfer to protect the surfaces from oxidation. In some embodiments, the chamber may be under vacuum or may be a shielded gas chamber with an inert or non-oxidizing gas present around the parts. In some embodiments, these steps may further include a polishing step, in which case 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 lower than 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. lower than 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 the part to be heated more evenly and continuously during the processing steps, allowing finer control over the rate at which elements diffuse within the part without melting the part. This improves the diffusion rate and reduces the chance of forming defects 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 is seen to include multiple core layers 402c and multiple intermediate layers 404c.

[0065] During the homogenization process, a foil such as foils 400a-c is held at a processing temperature for a period of time to allow interdiffusion of elements in the intermediate layer and the 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. Since 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 slower than elements with higher diffusion coefficients at the same concentration gradient, temperature, and other environmental conditions. Thus, the slowest diffusing element is the element with the lowest diffusion coefficient. Once the slowest diffusing element is present in both the regions previously occupied by the core and intermediate layers, the foil can be considered to be homogenous, and the peak composition of the slowest diffusing element is within the standard tolerance for the alloy composition in a published standard, such as TEAL sheet, as specified.

[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 progression series 508, 510, and 512 represent the concentrations of alloying elements at various times throughout the homogenization process. Series 508 represents the alloying element concentration at time t1, series 510 represents the alloying element concentration at time t2, series 512 represents the alloying element concentration at time t3, and t1 < t2 < t3. From t1 to t3, as the composition of the alloying 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 alloying elements in the core layer 504 increases. Series 514 represents the concentration of the alloying elements at the end of the homogenization process. As can be seen in profile 500, the concentration of the alloying 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 of 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 having a thinner intermediate layer does not require as much time for homogenization.

[0074] Similarly, the rate at which the diffusing element moves 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 to cool the part, 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 any of the constituent alloys. In some cases, the composition of the alloys 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 total 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 meets 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 those elements in the final homogenized part.

[0078] Step 702 includes receiving a desired alloy composition for the object. The desired alloy composition 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 a plurality of foils in a stack to form an object. As part of step 704, the type of foils deposited in the stack 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 where one of the core layer or 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 such that when spread using the methods 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 following table 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 can be alternated to produce the same grooved layer structure of alternating core and clad layers that can be produced by a stack of clad foils.

[0086] Step 706 includes applying heat at a first temperature to the stack to bond the foils together. The stack may include foils made up of multiple layers. Each layer may include, for example, an aluminum alloy, a magnesium alloy, or a titanium alloy. The alloy material may be aluminum, chromium, copper, lithium, magnesium, manganese, titanium, nickel, silicon, or zinc. The first temperature required to bond the foils together may 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 is about the solidus temperature of the foils or the desired alloy composition. In some embodiments, the second temperature may be the same as the first temperature.

[0088] Step 710 is optional and includes quenching the laminate after homogenization. This quenching step may be performed in the same processing unit where the homogenization step occurs, or may be performed at a separate processing unit from where the homogenization step occurs. An 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, the platen 805 may be at least one of a pressure plate or a heating plate. In some embodiments, the platen 805 may be configured to apply at least one of heat or pressure to an opposite side of the stack of layers 815. In some embodiments, the application of at least one of heat or pressure increases the temperature of the stack of layers 815 to a temperature below the melting temperature of the core layer of the foil 810, such that the at least one of heat or pressure bonds a first foil to a second foil in the stack of layers 815.

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

[0092] In some embodiments, the support regions 825, 830 are configured to conduct at least one of heat or pressure from the plate 805 through the stack of layers 815. Such conduction of heat or pressure facilitates bonding of the foil 810 to form the bonded object region 820. In some embodiments, the plate 805 applies at least one of heat or pressure to the support regions 825, 830, which in turn conducts at least one of heat or pressure to the object region 820. In some embodiments, the support regions 825, 830 may have flat surfaces, thus allowing the plate 805 to apply at least one of pressure or heat evenly across the surface. In some embodiments, the support region is a single support region surrounding the object region 820, which may be used to create a negative of the object. In some embodiments, the bonding process of the object region 820 may be performed under an oxidizing atmosphere, such as air. In some embodiments, the bonding process of the 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] FIG. 9 illustrates a schematic of a method 900 for additive manufacturing of an object by diffusion bonding according to one embodiment. The method 900 includes applying heat to a stack of foils to bring 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 raised to a bonding temperature and optional pressure (step 915) and held at the bonding temperature and optional pressure (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 part 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, pressure is released and another foil is added (step 920).

[0097] In some embodiments, the temperature can facilitate diffusion and bonding between elements of the added foil core layer and the body to effect 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 generate a temperature gradient across the object for the purpose of selectively promoting diffusion bonding in some regions of the object. In some embodiments, the diffusion process can be repeated until the object is complete.

[0099] 10 illustrates a schematic of 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 under oxidizing or non-oxidizing atmospheres 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 include between 20% and 100% aluminum. In some embodiments, the aluminum alloy foil may include 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 include more than 50% Cu. In some embodiments, the aluminum alloy foil may include more than 40% Fe. In some embodiments, the aluminum alloy foil may include more than 40% Mg. In some embodiments, the aluminum alloy foil may include more than 40% Ni. In some embodiments, the aluminum alloy foil may include more than 40% Zn. In some embodiments, the aluminum alloy foil may include 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 rare earth metals. 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 the energy costs and mechanical complexity of the process. 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 comprising at least one of Cu, Mg, Zn, or Si. In some embodiments, the intermediate layer may comprise at least 0.2% Cu. In some embodiments, the diffusible element may comprise at least 1% Cu. In some embodiments, the diffusible element may comprise at least 2% Cu. In some embodiments, the diffusible element may comprise up to 4% Cu. In some embodiments, the diffusible element may comprise up to 5% Cu. In some embodiments, the diffusible element may comprise up to 6% Cu. In some embodiments, the diffusible element may comprise up to 6.3% Cu.

[0107] In some embodiments, the method includes bringing the stack of foils 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 stack of foils 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 of the core layer into the intermediate layer and the rate of diffusion of elements of the intermediate layer into the core layer (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 foils changes to resemble the final average composition of the body, and the melting temperature increases in response to the composition change, hi some embodiments, new bonds are formed between the metallic components.

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

[0112] In some embodiments, the constituent interlayers of the previously deposited layers are already interdiffused and bonded to the core layer, so that the previously deposited layers are not affected by the process and, as a result, the part does not melt at the applied bonding temperature.

[0113] 11 illustrates 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 surface. 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 raised to a bonding temperature, step 1120. In some embodiments, the bonding temperature is greater than the melting temperature of the intermediate layer, but less than the melting temperature of the core layer of the foil.

[0116] In some embodiments, the foil may be held at the bonding temperature for a fixed period of time, step 1125. In some embodiments, holding the foil at the bonding temperature may melt the intermediate layer, which increases the diffusion rate of elements of the core layer into the intermediate layer, and correspondingly increases the diffusion rate of elements of 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 that includes 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 raised to a joining temperature, which 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 held at this bonding temperature for a fixed period of time (step 1125), which causes the intermediate layer of the applied foil to melt and the bonding process described above to occur.

[0121] In some embodiments, the constituent interlayers of the previously deposited layers are already melted and interdiffused with the core layer to bond the previously deposited layers, so that the previously deposited layers cannot be affected by this process, and as a result, the body does 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 wires, or a combination of the two powder compositions. These can then be joined and when diffused using the processes described above, the result is an object with a uniform composition that matches the desired composition, which may not be 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 procedures 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 a particular configuration 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 thus many of the elements are examples and do not limit the scope of the disclosure or claims.

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

[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 the example configurations (including implementation). However, the 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 is merely intended to present example configurations and is not intended to limit the scope, applicability or scope of the claimed configurations. Rather, the foregoing description of the configurations provides one skilled in the art with an enabling description for implementing the described techniques. Various changes may be made in the function and arrangement of elements without departing from the spirit or scope of the present disclosure.

Claims

1. 1. A method for manufacturing an object, comprising: receiving a desired alloy composition for the object; depositing a plurality of foils having at least two constituent compositions in a stack to form the object; applying heat at a first temperature to the laminate to bond the plurality of foils together; and applying heat to the laminate at a second temperature to homogenize the composition of the laminate. Including, The homogenized laminate has the desired alloy composition. method.

2. The method of claim 1 , wherein the plurality of foils are patterned.

3. The method of claim 1 , wherein the plurality of foils comprises sheets having at least two different compositions.

4. The method of claim 1 , wherein each foil comprises multiple layers.

5. The method of claim 4 , wherein each layer comprises an aluminum alloy, a magnesium alloy, or a titanium alloy.

6. The method of claim 1, wherein at least one of the constituent compositions includes at least one of aluminum, chromium, copper, lithium, magnesium, titanium, nickel, silicon, and zinc.

7. The method of claim 4 , wherein a first layer forms a core of the foil and a second layer forms a cladding of the foil.

8. The method of claim 1, wherein each foil is between 25 and 1000 micrometers thick.

9. The method of claim 1 , wherein the second temperature is below a melting point of the plurality of foils.

10. The method of claim 1, wherein each of the constituent compositions has a solidus temperature, and the second temperature is approximately equal to or lower than the lowest solidus temperature of the constituent compositions.

11. The method of claim 1 , wherein the first temperature and the second temperature are the same.

12. The method of claim 1 , wherein the application of heat at the first temperature occurs in a first processing unit and the application of heat at the second temperature occurs in a second processing unit.

13. The method of claim 12, wherein the laminate is maintained at the first temperature during movement from the first processing unit to the second processing unit.

14. The method of claim 1 further comprising the step of quenching the laminate after homogenizing.

15. The method of claim 12 , wherein the quenching step is performed in the second processing unit used to homogenize the laminate.

16. The method of claim 1 , wherein pressure is applied to the laminate during the application of heat at the first temperature, the application of heat at the second temperature, or both.

17. The method of claim 1 , wherein the desired alloy composition is a uniform composition that is not the same as the composition of the plurality of foils.

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