WO2019245922A1

WO2019245922A1 - Feedstocks for additively manufacturing aluminum alloy products and additively manufactured products made from the same

Info

Publication number: WO2019245922A1
Application number: PCT/US2019/037337
Authority: WO
Inventors: Lynette M. Karabin; Zhi Tang; Andreas Kulovits; Men Glenn Chu; Yijia GU
Original assignee: Arconic Inc
Current assignee: Howmet Aerospace Inc
Priority date: 2018-06-20
Filing date: 2019-06-14
Publication date: 2019-12-26
Anticipated expiration: 2020-12-20

Abstract

The present disclosure relates to feedstocks for additively manufacturing aluminum alloys. The new feedstocks may be capable of, for instance, producing grain refiners in-situ, whether during the feedstock manufacturing process, or the additive manufacturing process. Such in-situ production of grain refiners may, for instance, facilitate production of crack-free additively manufactured aluminum alloy products. The present disclosure also relates to additively manufactured products where in-situ grain refining may occur.

Description

FEEDSTOCKS FOR ADDITIVELY MANUFACTURING ALUMINUM ALLOY PRODUCTS AND ADDITIVELY MANUFACTURED PRODUCTS MADE FROM

THE SAME

FIELD OF THE DISCLOSURE

[001] The present disclosure generally relates to feedstocks for additively manufacturing aluminum alloys, and additively manufactured products made from such feedstocks.

BACKGROUND

[002] Aluminum alloy products are generally produced via either shape casting or wrought processes. Shape casting generally involves casting a molten aluminum alloy into its final form, such as via pressure-die, permanent mold, green- and dry-sand, investment, and plaster casting. Wrought products are generally produced by casting a molten aluminum alloy into ingot or billet. The ingot or billet is generally further hot worked, sometimes with cold work, to produce its final form.

SUMMARY OF THE INVENTION

[003] Broadly, the present disclosure relates to feedstocks for additively manufacturing aluminum alloys, and additively manufactured products made from such feedstocks. The new feedstocks may be capable of, for instance, producing grain refiners in-situ, whether during the feedstock manufacturing process or the additive manufacturing process. Such in- situ production of grain refiners may, for instance, facilitate production of crack-free additively manufactured aluminum alloy products.

[004] In one approach, and referring now to FIG. la, a method (100) may include one or more of the steps of (a) forming a molten liquid comprising an aluminum alloy and one or more grain refiner precursors (20), and (b) forming an additive manufacturing feedstock from the molten liquid (40). The method (100) may also include (c) using the additive manufacturing feedstock to produce an additively manufactured product (60). The forming an additive manufacturing feedstock step (40) may include reacting (43) the one or more grain refiner precursors with the aluminum of the aluminum alloy to form one or more aluminum-containing grain refiners. The aluminum-containing grain refmer(s) may facilitate production of crack-free additively manufacturing aluminum alloy products.

[005] As noted above, a method may include (a) forming a molten liquid comprising an aluminum alloy and one or more grain refiner precursors (20). For instance, and with reference now to FIG. 4a, a container (505) may include a molten liquid (510). In the illustrated embodiment of FIG. 4a, the molten liquid comprises a homogenous distribution of the aluminum alloy and the grain refiner precursor. The aluminum alloy of the molten liquid (520) may be any suitable aluminum alloy for production of additive manufacturing feedstocks for aluminum alloys. In one embodiment, and referring now to FIG. lb, the aluminum alloy (22) is generally one of a lxxx aluminum alloy, 2xxx aluminum alloy, 3xxx aluminum alloy, 6xxx aluminum alloy, 7xxx aluminum alloy, and 8xxx aluminum alloy. The Definitions section, below defines these aluminum alloys. Such alloys may be crack-prone due to, for instance, their hot tearing susceptibility. The 4xxx and 5xxx aluminum alloys (defined below), are generally not crack-prone, so, in some embodiments, the present disclosure does not relate to the in-situ production of grain refiners in either a 4xxx aluminum alloy or a 5xxx aluminum alloy.

[006] With continued reference to FIGS lb and 4a, the grain refiner precursor(s) of the molten liquid (510) may be any metal capable of reacting (43) with aluminum to form a grain refiner. Non-limiting examples of grain refiner precursor(s) include Sc, Ti, V, Cr, Zr, Nb, Mo, Lu, Hf, Ta, W and combinations thereof. The grain refiner precursor(s) may be in elemental form in the molten liquid (510) (e.g., to facilitate formation of the aluminum- containing grain refiners). Feedstocks containing grain refiner precursor(s) may include such grain refiner precursor(s) in elemental or compound form.

[007] Referring now to FIG. lb, the forming an additive manufacturing feedstock step (40) may include first cooling (42) the molten liquid to a temperature below its liquidus. This first cooling step (42) may at least partially facilitate the reacting step (43). In one embodiment, the first cooling step (42) comprises reacting (43) aluminum with the one or more grain refiner precursors to form the one or more aluminum-containing grain refiners. This in-situ formation of aluminum-containing grain refiners may facilitate the production of additive manufacturing feedstocks having a homogenous distribution of aluminum-containing grain refiners therein.

[008] The forming an additive manufacturing feedstock step (40) may include second cooling (44) the molten liquid to a temperature below its solidus, thereby forming at least a portion of the additively manufactured feedstock. The additively manufacturing aluminum alloy feedstock may comprise a homogenous distribution (46) of the one or more aluminum- containing grain refiners within an aluminum alloy matrix of the additive manufacturing feedstock. This feedstock may be in the form of a wire (47) or a powder (49).

[009] In one approach the molten liquid (510) is used to produce a powder feedstock. One embodiment of a system for producing a powder feedstock is shown in FIG. 4b, where an additively manufactured feedstock having a homogenous distribution of grain refiner therein may be produced by gas atomization. In the illustrated embodiment, the molten liquid (510) of FIG. 4a is provided to a tundish (515), such as by pouring the molten liquid (510) from a container (505). As illustrated in FIG. 4c, the molten liquid may comprise a homogenous distribution of the aluminum (Al) and the grain refiner precursor metal(s) (M). While the illustrated embodiment of FIGS. 4a-4b shows the production of an additive manufacturing feedstock (537) via gas atomization, other suitable methods may be used. For instance, an additive manufacturing feedstock (e.g., a powder) may be produced via any one or plasma atomization, gas atomization, or impingement of a molten liquid (e.g., solidification of an impinging molten metal droplet on a cold substrate), among others.

[0010] Referring back to FIG. 4a, the molten liquid (510) is provided from the tundish (515) to a gas atomization chamber (525) via atomization fluid (520). Droplets form in the chamber (525) as the molten liquid cools from its liquidus to its solidus temperature, ultimately forming an additive manufacturing feedstock powder (537). Although the liquidus is shown at the top of the chamber (525) and the solidus is shown at the bottom of the chamber (525), the liquidus and solidus points may vary.

[0011] Referring now to FIG. 4d, the droplets (535) formed from the molten liquid (510) in the chamber (525) generally include aluminum-containing grain refmer(s) (540) that formed due to the reaction (43) of the aluminum (Al) and the grain refiner precursor metal(s) (M). As illustrated, the droplets (535) generally comprise a homogenous distribution of the aluminum-containing grain refmer(s) within the aluminum alloy.

[0012] Referring now to FIG. 4e, solid particles (545) form from the droplets (535). The solid particles (545) at least partially make-up the additive manufacturing feedstock (537). The solid particles (545) may comprise aluminum grains (550) and the aluminum-containing grain refmer(s) (540). The solid particles (545) generally comprise a homogenous distribution of the aluminum-containing grain refmer(s) relative to the grains (550). The aluminum-containing grain refmer(s) (540) may be located within the grains (550) and/or along the boundaries of the grains (550), for instance.

[0013] FIG. 4f shows one embodiment of a Scheil solidification curve, wherein aluminum- containing grain refiners (540) are formed. In the illustrated embodiment, the aluminum (Al) reacts with the grain refiner precursor metal (M) to form Al₃M type intermetallics. Other aluminum-containing grain refiners types may be formed.

[0014] As noted above, the molten liquid generally comprises an aluminum alloy and one or more grain refiner precursors. The molten liquid may also comprise one or non-aluminum grain refiners. The one or non-aluminum grain refiners may remain solid material in the molten liquid.

[0015] Such non-aluminum grain refiners may further facilitate grain refining and/or production of crack-free additively manufactured aluminum alloy products. In one approach, the molten liquid (and thus the feedstock and/or thus the final additively manufactured product) contains an amount of the non-aluminum grain refiners to at least partially assist with grain refining. In another approach, a molten liquid and/or an additive manufacturing feedstock and/or a final additively manufactured product contains low amounts of non aluminum grain refiners (e.g., to achieve improved properties), such as not greater than 1.0 wt. % of non-aluminum grain refiners. In one embodiment, a molten liquid and/or an additive manufacturing feedstock and/or a final additively manufactured product contains not greater than 0.75 wt. % of non-aluminum grain refiners. In another embodiment, a molten liquid and/or an additive manufacturing feedstock and/or a final additively manufactured product contains not greater than 0.75 wt. % of non-aluminum grain refiners. In yet another embodiment, a molten liquid and/or an additive manufacturing feedstock and/or a final additively manufactured product contains not greater than 0.50 wt. % of non-aluminum grain refiners. In another embodiment, a molten liquid and/or an additive manufacturing feedstock and/or a final additively manufactured product contains not greater than 0.35 wt. % of non aluminum grain refiners. In yet another embodiment, a molten liquid and/or an additive manufacturing feedstock and/or a final additively manufactured product contains not greater than 0.25 wt. % of non-aluminum grain refiners. In another embodiment, a molten liquid and/or an additive manufacturing feedstock and/or a final additively manufactured product contains not greater than 0.15 wt. % of non-aluminum grain refiners. In yet another embodiment, a molten liquid and/or an additive manufacturing feedstock and/or a final additively manufactured product contains not greater than 0.10 wt. % of non-aluminum grain refiners. In another embodiment, a molten liquid and/or an additive manufacturing feedstock and/or a final additively manufactured product contains not greater than 0.08 wt. % of non aluminum grain refiners. In yet another embodiment, a molten liquid and/or an additive manufacturing feedstock and/or a final additively manufactured product contains not greater than 0.05 wt. % of non-aluminum grain refiners. In another embodiment, a molten liquid and/or an additive manufacturing feedstock and/or a final additively manufactured product contains not greater than 0.03 wt. % of non-aluminum grain refiners. In yet another embodiment, a molten liquid and/or an additive manufacturing feedstock and/or a final additively manufactured product contains not greater than 0.01 wt. % of non-aluminum grain refiners. In another embodiment, a molten liquid and/or an additive manufacturing feedstock and/or a final additively manufactured product contains not greater than 0.007 wt. % of non aluminum grain refiners. In yet another embodiment, a molten liquid and/or an additive manufacturing feedstock and/or a final additively manufactured product contains not greater than 0.005 wt. % of non-aluminum grain refiners. In another embodiment, a molten liquid and/or an additive manufacturing feedstock and/or a final additively manufactured product contains not greater than 0.003 wt. % of non-aluminum grain refiners. In yet another embodiment, a molten liquid and/or an additive manufacturing feedstock and/or a final additively manufactured product contains not greater than 0.001 wt. % of non-aluminum grain refiners.

[0016] Referring back to FIG. la, the formed additive manufacturing feedstock may be used (60) in an additive manufacturing apparatus to produce one or more additively manufactured products. The aluminum-containing grain refmer(s) may facilitate production of crack-free additively manufacturing aluminum alloy products (e.g., in the as-built condition). In one embodiment, and referring now to FIG. 2, during the additive manufacturing, at least a portion of the feedstock is heated above its liquidus, thereby forming a melt pool. In other words, a method (200) may comprise forming, in an additive manufacturing apparatus, a molten liquid in the form of a melt pool (210). Due to being heated above its liquidus temperature, this melt pool may comprise the aluminum and the one or more grain refiner precursors of the feedstock. During the additive manufacturing process, this melt pool may rapidly cool, during which at least some of the grain refiner precursor(s) react with the aluminum to form aluminum-containing grain refiners, which aluminum-containing grain refiners may facilitate grain formation / nucleation. In other words, the method (200) may comprise first cooling the molten liquid/melt pool to a temperature below its liquidus (220), and second cooling the molten liquid/melt pool to a temperature below its solidus (230). The first cooling (220) may comprise reacting the one or more grain refiner precursors with aluminum to form one or more aluminum-containing grain refiners (222). The second cooling (230) may comprise forming at least a portion of an additively manufactured product. Due to the first cooling (220) and second cooling (230), the portion of the additively manufactured product may comprise a homogenous distribution of the one or more aluminum-containing grain refiners within the aluminum alloy matrix of the portion of the additively manufactured product (232). In one embodiment, during at least one of the first cooling step (b) and the second cooling step (c), one or more grains of the additively manufactured product may be nucleated via the one or more aluminum-containing grain refiners. In other words, the method (200) may comprise nucleating one or more grain grains of the additively manufactured product via the one or more aluminum-containing grain refiners during at least one of the first cooling step (b) and the second cooling step (c). Thus, in-situ grain refining during additive manufacturing may be achieved. In other words, at least partially due to the nucleating, in-situ grain refining is accomplished. In turn, a final additive manufactured product may include a plurality of grains and the aluminum-containing grain refiners may be homogenously distributed within the final additive manufactured products (e.g., in the as-built condition). At least partially due to the aluminum-containing grain refiners, the final additive manufactured product may be crack-free (234) (e.g., in the as-built condition).

[0017] In one embodiment, the aluminum-containing grain refiners facilitate production of final additive manufactured products having equiaxed grains. Equiaxed grains may facilitate production of crack-free additively manufactured aluminum alloy products. In one embodiment, an additively manufactured aluminum alloy product comprises grains and wherein at least 50 vol. % of the grains are equiaxed grains. In another embodiment, an additively manufactured aluminum alloy product comprises at least 60 vol.% equiaxed grains. In yet another embodiment, an additively manufactured aluminum alloy product comprises at least 70 vol.% equiaxed grains. In another embodiment, an additively manufactured aluminum alloy product comprises at least 80 vol.% equiaxed grains. In yet another embodiment, an additively manufactured aluminum alloy product comprises at least 90 vol.% equiaxed grains. In another embodiment, an additively manufactured aluminum alloy product comprises at least 95 vol.% equiaxed grains. In yet another embodiment, an additively manufactured aluminum alloy product comprises at least 97 vol.% equiaxed grains. In another embodiment, an additively manufactured aluminum alloy product comprises at least 99 vol.% equiaxed grains. In yet another embodiment, an additively manufactured aluminum alloy product consists essentially of equiaxed grains.

[0018] In one embodiment, an average grain size of the equiaxed grains is from 0.5 - 50 micrometers (e.g., in the as-built condition). In one embodiment, the average size of the equiaxed grains of the additively manufactured aluminum alloy product in the as-built condition is generally not greater than 50 microns. In one embodiment, the average size of the equiaxed grains of the additively manufactured aluminum alloy product in the as-built condition is not greater than 40 microns. In another embodiment, the average size of the equiaxed grains of the additively manufactured aluminum alloy product in the as-built condition is not greater than 30 microns. In yet another embodiment, the average size of the equiaxed grains of the additively manufactured aluminum alloy product in the as-built condition is not greater than 20 microns. In another embodiment, the average size of the equiaxed grains of the additively manufactured aluminum alloy product in the as-built condition is not greater than 10 microns. In yet another embodiment, the average size of the equiaxed grains of the additively manufactured aluminum alloy product in the as-built condition is not greater than 5 microns. In another embodiment, the average size of the equiaxed grains of the additively manufactured aluminum alloy product in the as-built condition is not greater than 4 microns. In yet another embodiment, the average size of the equiaxed grains of the additively manufactured aluminum alloy product in the as-built condition is not greater than 3 microns. In another embodiment, the average size of the equiaxed grains of the additively manufactured aluminum alloy product in the as-built condition is not greater than 2 microns, or less.

[0019] In one embodiment, the final additively manufactured product is built from a crack- prone aluminum alloy. In one embodiment, the crack-prone aluminum alloy is a lxxx aluminum alloy. In another embodiment, the crack-prone aluminum alloy is a 2xxx aluminum alloy. In yet another embodiment, the crack-prone aluminum alloy is a 3xxx aluminum alloy. In another embodiment, the crack-prone aluminum alloy is a 6xxx aluminum alloy. In yet another embodiment, the crack-prone aluminum alloy is a 7xxx aluminum alloy. In another embodiment, the crack-prone aluminum alloy is a 8xxx aluminum alloy.

[0020] Referring now to FIG. 3, in one embodiment a method (300) may include determining which alloys of a group of aluminum alloys are prone to cracking (5) during additive manufacturing. For instance, computer modeling or testing may be conducted on multiple (two or more) aluminum alloys to determine if such alloys are crack-prone. If an alloy is determined (5) to be crack-prone, the method may further include determining an amount of grain refiner precursor and/or aluminum-containing grain refiner to utilize in a crack-prone alloy to additively manufacture / produce a crack-free version of the aluminum alloy product. The method (300) may further include the forming a molten liquid step (20), as previously described, and based on the determined amount of grain refiner precursor and/or the determined amount of aluminum-containing grain refiner, wherein the molten metal includes a determined amount of the grain refiner precursor. The grain refiner precursor may be dissolved in the molten liquid to facilitate production of the additive manufacturing feedstock. In one embodiment, testing and/or modeling is conducted on a selected group of aluminum alloys to determine which alloys of the group are crack-prone. In one embodiment, the selected group of aluminum alloys is a group of 2xxx aluminum alloys. In another embodiment, the selected group of aluminum alloys is a group of 3xxx aluminum alloys. In yet another embodiment, the selected group of aluminum alloys is a group of 6xxx aluminum alloys. In another embodiment, the selected group of aluminum alloys is a group of 7xxx aluminum alloys. In yet another embodiment, the selected group of aluminum alloys is a group of 8xxx aluminum alloys.

[0021] The method (300) may further include forming the additive manufacturing feedstock (30) and the using the feedstock steps, as previously described, wherein a crack-free additively manufactured product is produced from a crack-prone aluminum alloy using a determined amount of grain refiner precursor and/or the determined amount of aluminum- containing grain refiner.

[0022] In one embodiment, the amount of grain refiner precursor to use in one or more crack- prone aluminum alloys is determined. In one embodiment, the amount of grain refiner precursor is at least 0.20 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 0.25 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 0.30 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 0.35 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 0.40 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 0.45 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 0.50 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 0.55 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 0.60 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 0.65 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 0.70 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 0.75 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 0.80 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 0.85 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 0.90 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 0.95 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 1.00 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 1.10 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 1.20 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 1.30 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 1.40 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 1.50 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 1.60 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 1.70 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 1.80 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 1.90 wt. % relative to the final additively manufactured aluminum alloy product. In another embodiment, the amount of grain refiner precursor is at least 2.0 wt. % relative to the final additively manufactured aluminum alloy product, or more. In any of these embodiments, the aluminum alloy may be a lxxx aluminum alloy. In any of these embodiments, the aluminum alloy may be a 2xxx aluminum alloy. In any of these embodiments, the aluminum alloy may be a 3xxx aluminum alloy. In any of these embodiments, the aluminum alloy may be a 4xxx aluminum alloy. In any of these embodiments, the aluminum alloy may be a 5xxx aluminum alloy. In any of these embodiments, the aluminum alloy may be a 6xxx aluminum alloy. In any of these embodiments, the aluminum alloy may be a 7xxx aluminum alloy. In any of these embodiments, the aluminum alloy may be a 8xxx aluminum alloy. In any of these embodiments, the grain refiner precursor may be selected from the group consisting of Sc, Lu, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W and combinations thereof. In any of these embodiments, the grain refiner precursor may be selected from the group consisting of Sc, Ti, Zr, Nb, Hf, Ta and combinations thereof. In any of these embodiments, the grain refiner precursor may be selected from the group consisting of Sc, Ti, Zr and combinations thereof. In one embodiment, the determined grain refiner precursor is a determined amount of titanium. In one embodiment, the determined grain refiner precursor is a determined amount of zirconium. In one embodiment, the determined grain refiner precursor is a determined combined amount of titanium and zirconium.

[0023] In one embodiment, the amount of aluminum-containing grain refiner is determined. In one embodiment, a final additively manufactured aluminum alloy product comprises at least 0.275 wt. % of the aluminum-containing grain refiners. In another embodiment, a final additively manufactured aluminum alloy product comprises at least 0.35 wt. % of the aluminum-containing grain refiners. In yet another embodiment, a final additively manufactured aluminum alloy product comprises at least 0.5 wt. % of the aluminum- containing grain refiners. In another embodiment, a final additively manufactured aluminum alloy product comprises at least 0.8 wt. % of the aluminum-containing grain refiners. In yet another embodiment, a final additively manufactured aluminum alloy product comprises at least 1.0 wt. % of the aluminum-containing grain refiners. In another embodiment, a final additively manufactured aluminum alloy product comprises at least 1.2 wt. % of the aluminum-containing grain refiners. In yet another embodiment, a final additively manufactured aluminum alloy product comprises at least 1.4 wt. % of the aluminum- containing grain refiners. In another embodiment, a final additively manufactured aluminum alloy product comprises at least 1.6 wt. % of the aluminum-containing grain refiners. In yet another embodiment, a final additively manufactured aluminum alloy product comprises at least 1.8 wt. % of the aluminum-containing grain refiners. In another embodiment, a final additively manufactured aluminum alloy product comprises at least 2.0 wt. % of the aluminum-containing grain refiners. In yet another embodiment, a final additively manufactured aluminum alloy product comprises at least 2.2 wt. % of the aluminum- containing grain refiners. In another embodiment, a final additively manufactured aluminum alloy product comprises at least 2.4 wt. % of the aluminum-containing grain refiners. In yet another embodiment, a final additively manufactured aluminum alloy product comprises at least 2.6 wt. % of the aluminum-containing grain refiners. In another embodiment, a final additively manufactured aluminum alloy product comprises at least 2.8 wt. % of the aluminum-containing grain refiners. In yet another embodiment, a final additively manufactured aluminum alloy product comprises at least 3.0 wt. % of the aluminum- containing grain refiners. In another embodiment, a final additively manufactured aluminum alloy product comprises at least 3.25 wt. % of the aluminum-containing grain refiners. In yet another embodiment, a final additively manufactured aluminum alloy product comprises at least 3.5 wt. % of the aluminum-containing grain refiners. In another embodiment, a final additively manufactured aluminum alloy product comprises at least 3.75 wt. % of the aluminum-containing grain refiners. In yet another embodiment, a final additively manufactured aluminum alloy product comprises at least 4.0 wt. % of the aluminum- containing grain refiners. In another embodiment, a final additively manufactured aluminum alloy product comprises at least 4.25 wt. % of the aluminum-containing grain refiners. In yet another embodiment, a final additively manufactured aluminum alloy product comprises at least 4.5 wt. % of the aluminum-containing grain refiners. In another embodiment, a final additively manufactured aluminum alloy product comprises at least 4.75 wt. % of the aluminum-containing grain refiners. In yet another embodiment, a final additively manufactured aluminum alloy product comprises at least 5.0 wt. % of the aluminum- containing grain refiners. In another embodiment, a final additively manufactured aluminum alloy product comprises at least 5.25 wt. % of the aluminum-containing grain refiners. In any of these embodiments, the aluminum alloy may be a lxxx aluminum alloy. In any of these embodiments, the aluminum alloy may be a 2xxx aluminum alloy. In any of these embodiments, the aluminum alloy may be a 3xxx aluminum alloy. In any of these embodiments, the aluminum alloy may be a 4xxx aluminum alloy. In any of these embodiments, the aluminum alloy may be a 5xxx aluminum alloy. In any of these embodiments, the aluminum alloy may be a 6xxx aluminum alloy. In any of these embodiments, the aluminum alloy may be a 7xxx aluminum alloy. In any of these embodiments, the aluminum alloy may be a 8xxx aluminum alloy. In any of these embodiments, the aluminum-containing grain refiners may comprise Al-RE-type, Al-TM- type, AhX-type compounds, and combinations thereof. In one embodiment, the aluminum- containing grain refiners comprise AhX-type compounds, where X is selected from the group consisting of Sc, Lu, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W and combinations thereof. In any of these embodiments, the aluminum-containing grain refiner may comprise AhX-type compounds, where X is selected from the group consisting of Sc, Ti, Zr, Nb, Hf, Ta and combinations thereof. In any of these embodiments, the aluminum-containing grain refiner may comprise AhX-type compounds, where X is selected from the group consisting of Sc, Ti, Zr and combinations thereof. In one embodiment, the determined aluminum-containing grain refiner is a determined amount of AhTi. In one embodiment, the determined aluminum-containing grain refiner is a determined amount of AhZr. In one embodiment, the determined aluminum-containing grain refiners are a determined combined amount of Al₃Ti and AhZr.

[0024] The new aluminum alloy products / bodies of the new aluminum alloys described herein may be suitable in aerospace and/or automotive applications. Non-limiting examples of aerospace applications may include heat exchangers and turbines. In one embodiment, a new aluminum alloy product / body is in the form of a compressor component (e.g., turbocharger impeller wheels). Non-limiting examples of automotive applications may include interior or exterior trim/appliques, pistons, valves, and/or turbochargers. Other examples include any components close to a hot area of the vehicle, such as engine components and/or exhaust components, such as the manifold. A new aluminum alloy product may be in the form of an engine component for an aerospace or automotive vehicle, wherein the method comprises incorporating the engine component into the aerospace or automotive vehicle. A method may include operating such an aerospace or automotive vehicle. In any of the above embodiments, the final aluminum alloy product may be a compressor wheel for a turbocharger. In any of the above embodiments, the final aluminum alloy product may be one of a heat exchanger and a piston.

[0025] Aside from the applications described above, the new aluminum alloy bodies of the present disclosure may also be utilized in a variety of consumer products, such as any consumer electronic products, including laptops, cell phones, cameras, mobile music players, handheld devices, computers, televisions, microwave, cookware, washer/dryer, refrigerator, sporting goods, or any other consumer electronic product requiring durability and selective visual appearance. In one embodiment, the visual appearance of the consumer electronic product meets consumer acceptance standards.

[0026] In some embodiments, the new aluminum alloy bodies of the present disclosure may be utilized in a variety of products including non-consumer products including the likes of medical devices, transportation systems and security systems, to name a few. In other embodiments, the new aluminum alloy bodies may be incorporated in goods including the likes of car panels, media players, bottles and cans, office supplies, packages and containers, among others.

Definitions

[0027] As used herein, “homogenous distribution” means a mixture having a generally uniform distribution of matter. As noted in“ Chemistry” by Zumdahl, S. S. (1989), D.C. Heath and Co, page 24: “A homogenous mixture is called a solution. Air is a solution consisting of a mixture of gases. Wine is a complex liquid solution. Brass is a solid solution of coper and zinc.”

The molten liquids / melt pools described herein comprising the aluminum and the grain refiner precursors are liquid solutions of aluminum and the grain refiner precursors, and thus comprise a homogenous distribution of the aluminum and grain refiner precursors. See, e.g., FIG. 4c. The solid materials made from these molten liquids / melt pools may also have a uniform distribution of the aluminum and the aluminum-containing grain refiners (e.g., when rapidly solidified), and thus may comprise a homogenous distribution of the aluminum- containing grain refiners within the aluminum matrix of the solid material. See, e.g, FIGS. 4d-4e.

[0028] As used herein,“additive manufacturing” means“a process of joining materials to make objects from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing methodologies”, as defined in ASTM F2792-l2a entitled “Standard Terminology for Additively Manufacturing Technologies”. Non-limiting examples of additive manufacturing processes useful in producing crack-free aluminum alloy products include, for instance, DMLS (direct metal laser sintering), SLM (selective laser melting), SLS (selective laser sintering), and EBM (electron beam melting), among others. Any suitable feedstocks may be used, including one or more powders, one or more wires, and combinations thereof. In some embodiments the additive manufacturing feedstock is comprised of one or more powders. Shavings are types of particles. In some embodiments, the additive manufacturing feedstock is comprised of one or more wires. A ribbon is a type of wire.

[0029] As used herein, a "lxxx aluminum alloy" is an aluminum alloy comprising at least 99.00 wt. % Al, as defined by“International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys” (2015) (a.k.a.,“the Teal Sheets”), optionally comprising tolerable levels of oxygen (e.g., from about 0.01 to 0.20 wt. % O) therein due to normal additive manufacturing processes. The“lxxx aluminum alloy” compositions include the lxx aluminum casting and ingot compositions, as defined by the Aluminum Association document“Designations and Chemical Composition Limits for Aluminum Alloys in the Form of Castings and Ingot” (2009) (a.k.a.,“the Pink Sheets”), incorporated herein by reference in its entirety. The term "lxxx aluminum alloy" includes pure aluminum products (e.g., 99.99% Al products). As used herein, the term “lxxx aluminum alloy” only refers to the composition and not any associated processing, i.e., as used herein a lxxx aluminum alloy product does not need to be a wrought product to be considered a lxxx aluminum alloy composition/product described herein,

[0030] A“2xxx aluminum alloy” is an aluminum alloy comprising copper (Cu) as the predominate alloying ingredient, except for aluminum, optionally comprising tolerable levels of oxygen (e.g., from about 0.01 to 0.20 wt. % O) therein due to normal additive manufacturing processes. The 2xxx aluminum alloy compositions include the 2xx alloy compositions of the Pink Sheets. Also, as used herein, the term“2xxx aluminum alloy” only refers to the composition and not any associated processing, i.e., as used herein a 2xxx aluminum alloy product does not need to be a wrought product to be considered a 2xxx aluminum alloy composition/product described herein.

[0031] A“3xxx aluminum alloy” is an aluminum alloy comprising manganese (Mn) as the predominate alloying ingredient, except for aluminum, optionally comprising tolerable levels of oxygen (e.g., from about 0.01 to 0.20 wt. % O) therein due to normal additive manufacturing processes. Also, as used herein, the term“3xxx aluminum alloy” only refers to the composition and not any associated processing, i.e., as used herein a 3xxx aluminum alloy product does not need to be a wrought product to be considered a 3xxx aluminum alloy composition/product described herein.

[0032] A“4xxx aluminum alloy” is an aluminum alloy comprising silicon (Si) as the predominate alloying ingredient, except for aluminum, optionally comprising tolerable levels of oxygen (e.g., from about 0.01 to 0.20 wt. % O) therein due to normal additive manufacturing processes. The 4xxx aluminum alloy compositions include the 3xx alloy compositions and the 4xx alloy compositions of the Pink Sheets. Also, as used herein, the term “4xxx aluminum alloy” only refers to the composition and not any associated processing, i.e., as used herein a 4xxx aluminum alloy product does not need to be a wrought product to be considered a 4xxx aluminum alloy composition/product described herein.

[0033] A“5xxx aluminum alloy” is an aluminum alloy comprising magnesium (Mg) as the predominate alloying ingredient, except for aluminum, optionally comprising tolerable levels of oxygen (e.g., from about 0.01 to 0.20 wt. % O) therein due to normal additive manufacturing processes. The 5xxx aluminum alloy compositions include the 5xx alloy compositions of the Pink Sheets. Also, as used herein, the term“5xxx aluminum alloy” only refers to the composition and not any associated processing, i.e., as used herein a 5xxx aluminum alloy product does not need to be a wrought product to be considered a 5xxx aluminum alloy composition/product described herein. [0034] A “6xxx aluminum alloy” is an aluminum alloy comprising both silicon and magnesium, and in amounts sufficient to form the precipitate Mg₂Si, optionally comprising tolerable levels of oxygen (e.g., from about 0.01 to 0.20 wt. % O) therein due to normal additive manufacturing processes. Also, as used herein, the term“6xxx aluminum alloy” only refers to the composition and not any associated processing, i.e., as used herein a 6xxx aluminum alloy product does not need to be a wrought product to be considered a 6xxx aluminum alloy composition/product described herein.

[0035] A “7xxx aluminum alloy” is an aluminum alloy comprising zinc (Zn) as the predominate alloying ingredient, except for aluminum, optionally comprising tolerable levels of oxygen (e.g., from about 0.01 to 0.20 wt. % O) therein due to normal additive manufacturing processes. The 7xxx aluminum alloy compositions include the 7xx alloy compositions of the Pink Sheets. Also, as used herein, the term“7xxx aluminum alloy” only refers to the composition and not any associated processing, i.e., as used herein a 7xxx aluminum alloy product does not need to be a wrought product to be considered a 7xxx aluminum alloy composition/product described herein.

[0036] A“8xxx aluminum alloy” is any aluminum alloy that is not a lxxx-7xxx aluminum alloy. Examples of 8xxx aluminum alloys include alloys having iron or lithium as the predominate alloying element, other than aluminum, optionally comprising tolerable levels of oxygen (e.g., from about 0.01 to 0.20 wt. % O) therein due to normal additive manufacturing processes. The 8xxx aluminum alloy compositions include the 8xx alloy compositions and 9xx alloy compositions of the Pink Sheets. As noted in ANSI H35.1 (2009), referenced by the Pink Sheets, the 9xx alloy compositions are aluminum alloys with“other elements” other than copper, silicon, magnesium, zinc, and tin, as the major alloying element. Also, as used herein, the term“8xxx aluminum alloy” only refers to the composition and not any associated processing, i.e., as used herein an 8xxx aluminum alloy product does not need to be a wrought product to be considered an 8xxx aluminum alloy composition/product described herein.

[0037] As used herein, a“grain refiner” is a compound that facilitates aluminum alloy crystal formation. In one embodiment, a“grain refiner” is an aluminum-containing grain refiner.

[0038] As used herein, an “aluminum-containing grain refiner” means a grain refiner compound comprising aluminum. Examples of aluminum-containing grain refiners include aluminum-rare earth type compounds (“Al-RE-type”), aluminum-transition metal type compounds (“Al-TM-type”), and AhX-type compounds, among others. [0039] As used herein,“Al-RE-type compound” means a compound comprising aluminum and at least one rare earth metal. In one embodiment, an Al-RE-type compound comprises at least one of Sc and Lu. In one embodiment, an Al-RE-type compound consists essentially of aluminum and scandium. In one embodiment, an Al-RE-type compound consists essentially of aluminum and lutetium.

[0040] As used herein,“Al-TM-type compounds” means a compound comprising aluminum and at least one transition metal. In one embodiment, an Al-TM-type compound comprises at least one of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and W. In one embodiment, an Al-TM-type compound consists essentially of aluminum and titanium. In another embodiment, an Al- TM-type compound consists essentially of aluminum and vanadium. In yet another embodiment, an Al-TM-type compound consists essentially of aluminum and chromium. In another embodiment, an Al-TM-type compound consists essentially of aluminum and zirconium. In yet another embodiment, an Al-TM-type compound consists essentially of aluminum and niobium. In another embodiment, an Al-TM-type compound consists essentially of aluminum and molybdenum. In yet another embodiment, an Al-TM-type compound consists essentially of aluminum and hafnium. In another embodiment, an Al- TM-type compound consists essentially of aluminum and tantalum. In yet another embodiment, an Al-TM-type compound consists essentially of aluminum and tungsten.

[0041] As used herein,“AhX-type compound” means a compound comprising aluminum and one or more metals, where the compound has a stoichiometric ratio of three aluminum atoms to the one or more metals. An AhX-type compound may include one or more rare earth metals and thus may be a species of an Al-RE-type compound. Similarly, an AhX-type compound may include one or more transition metals and thus may be a species of an Al- TM-type compound. In one embodiment, AhX-type compounds may form where X is one or more metals. In one embodiment, X is a single metal. In another embodiment, X includes multiple metals. For instance, Ah(Sc,Zr) compounds may form, where the stoichiometric relationship exists between the aluminum and scandium plus zirconium in combination. In one embodiment, X is selected from the group consisting of Sc, Lu, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and combinations thereof. In another embodiment, X is selected from the group consisting of Sc, Ti, Zr and combinations thereof. In one embodiment, X is Ti. In another embodiment, X is Sc. In another embodiment, X is Zr. AhX-type compounds may realize a crystal structure of at least one of a Ll₂ structure, a D0₂₂ structure, or a D0₂₃ structure, among others. [0042] As used herein,“non-aluminum grain refiner” means grain refiner materials that do not contain aluminum. Suitable non-aluminum grain refiners include, for instance, ceramic materials. Ceramics include oxide materials, boride materials, carbide materials, nitride materials, silicon materials, carbon materials, and/or combinations thereof. Some additional examples of ceramics include metal oxides, metal borides, metal carbides, metal nitrides and/or combinations thereof. Additionally, some non-limiting examples of ceramics include: TiB, TiB₂, TiC, SiC, BC, BN, Si₃N₄, their suitable equivalents, and/or combinations thereof.

[0043] As used herein,“grain” takes on the meaning defined in ASTM El 12 §3.2.2, i.e.,“the area within the confines of the original (primary) boundary observed on the two-dimensional plane of-polish or that volume enclosed by the original (primary) boundary in the three- dimensional object”.

[0044] As used herein, the“grain size” is calculated by the following equation:

. AAL

v/ = square root (— )

• wherein A i is the area of the individual grain as measured using commercial software Edax OIM version 8.0 or equivalent; and

• wherein vi is the calculated individual grain size assuming the grain is a circle. Grain size is determined based on a two-dimensional plane that includes the build direction of the additively manufactured product.

[0045] As used herein, the“area weighted average grain size” is calculated by the following equation

v-bar

• wherein A i is the area of each individual grain as measured using commercial software Edax OIM version 8.0 or equivalent;

• wherein vi is the calculated individual grain size assuming the grain is a circle; and

• wherein v-bar is the area weighted average grain size.

[0046] As used herein,“equiaxed grains” means grains having an average aspect ratio of less than 4: 1 as measured in the XY, YZ, and XZ planes. The“aspect ratio” is determined using commercial software Edax OIM version 8.0 or equivalent. The commercial software fits an ellipse to the perimeter points of the grain. As used herein,“aspect ratio” is the inverse of: the length of the minor axis of the ellipse divided by the length of the major axis of the ellipse as determined using commercial software. In one embodiment, an additively manufactured aluminum alloy part comprises equiaxed grains having an average aspect ratio of not greater than 4: 1. In one embodiment, an additively manufactured aluminum alloy part comprises equiaxed grains having an average aspect ratio of not greater than 3: 1. In one described embodiment, an additively manufactured aluminum alloy part comprises equiaxed grains having an average aspect ratio of not greater than 2: 1. In one embodiment, an additively manufactured aluminum alloy part comprises equiaxed grains having an average aspect ratio of not greater than 1.5: 1. In one embodiment, an additively manufactured aluminum alloy part comprises equiaxed grains having an average aspect ratio of not greater than 1.1 : 1. The amount (volume percent) of equiaxed grains in the additively manufactured product in the as- built condition may be determined by EBSD (electron backscatter diffraction) analysis of a suitable number of SEM micrographs of the additively manufactured product in the as-built condition. Generally at least 5 micrographs should be analyzed.

[0047] In some embodiments, the additively manufactured product is a crack-free product. In some embodiments,“crack-free” means that the product is sufficiently free of cracks such that it can be used for its intended, end-use purpose. The determination of whether a product is“crack-free” may be made by any suitable method, such as, by visual inspection, dye penetrant inspection, and/or by non-destructive test methods. In some embodiments, the non destructive test method is a computed topography scan (“CT scan”) inspection (e.g., by measuring density differences within the product). In one embodiment, an aluminum alloy product is determined to be crack-free by visual inspection. In another embodiment, an aluminum alloy product is determined to be crack-free by dye penetrant inspection. In yet another embodiment, an aluminum alloy product is determined to be crack-free by CT scan inspection, as evaluated in accordance with ASTM E1441. In another embodiment, an aluminum alloy product is determined to be crack-free during an additive manufacturing process, wherein in-situ monitoring of the additively manufactured build is employed.

[0048] As used herein, the “as-built condition” means the condition of the additively manufactured aluminum alloy product after production and absent of any subsequent mechanical, thermal or thermomechanical treatments.

[0049] As used herein,“crack-prone aluminum alloy” means an aluminum alloy that is prone to cracking during solidification (e.g., during rapid solidification (e.g., during additive manufacturing; during shape casting); during ingot production). In one embodiment, a crack- prone aluminum alloy is an aluminum alloy having a hot cracking susceptibility index of at least 2000°C, wherein the hot cracking susceptibility index is the maximum absolute value of the derivative of temperature (in °C) versus the square root of the weight fraction of solids (Vf_s) for the particular aluminum alloy in question as calculated using the Scheil solidification model (complete diffusion in the liquid; no diffusion in the solid) implemented in commercial software PANDAT^®, for the interval of 0.97 < f_s < 0.99. This method is also described in the following journal article: S. Kou.“A Simple Index for Predicting the Susceptibility to Solidification Cracking,” Welding Journal, v.94, 2015, p. 374-s.

[0050] Throughout the specification and claims, the following terms take the meanings explicitly associated herein, unless the context clearly dictates otherwise. The phrases“in one embodiment” and“in some embodiments” as used herein do not necessarily refer to the same embodiment s), though they may. Furthermore, the phrases“in another embodiment” and“in some other embodiments” as used herein do not necessarily refer to a different embodiment, although they may. Thus, as described below, various embodiments of the invention may be readily combined, without departing from the scope or spirit of the invention.

[0051] In addition, as used herein, the term“or” is an inclusive“or” operator, and is equivalent to the term“and/or,” unless the context clearly dictates otherwise. The term “based on” is not exclusive and allows for being based on additional factors not described, unless the context clearly dictates otherwise. In addition, throughout the specification, the meaning of“a,”“an,” and“the” include plural references, unless the context clearly dictates otherwise. The meaning of“in” includes“in” and“on”, unless the context clearly dictates otherwise.

[0052] While a number of embodiments of the present invention have been described, it is understood that these embodiments are illustrative only, and not restrictive, and that many modifications may become apparent to those of ordinary skill in the art. Further still, unless the context clearly requires otherwise, the various steps may be carried out in any desired order, and any applicable steps may be added and/or eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] FIG. la is flow chart showing one embodiment of a method for producing additive manufacturing feedstocks.

[0054] FIG. lb is flow chart showing additional embodiments of FIG. la.

[0055] FIG. 2 is a flow chart showing one embodiment of a method for producing crack-free aluminum alloy products by additive manufacturing. [0056] FIG. 3 is a flow chart showing another embodiment of a method for producing crack- free aluminum alloy products by additive manufacturing.

[0057] FIG. 4a is a schematic side view of a container having a molten liquid therein.

[0058] FIG. 4b is a schematic side view of a system for producing an additive manufacturing feedstock in the form of a powder.

[0059] FIG. 4c is a schematic, close-up view of a molten liquid showing a homogenous distribution of grain refiner precursor metal(s) in the molten liquid.

[0060] FIG. 4d is a schematic, close-up view of a droplet showing a homogenous distribution of aluminum-containing grain refiners in the droplet.

[0061] FIG. 4e is a schematic, close-up view of a solid particle showing a homogenous distribution of aluminum-containing grain refiners in the particle.

[0062] FIG. 4f is a graph showing a hypothetical embodiment of a Scheil solidification curve.

[0063] FIG. 5a is an SEM image of a laser remelted specimen of conventional alloy 2219 (conventional composition).

[0064] FIG. 5b is an SEM image of a laser remelted specimen of an experimental version of alloy 2219 (experimental composition having an additional 2 wt. % Ti (approx.)).

[0065] FIG. 5c is close-up view of the SEM image of 5b.

[0066] FIG. 5d is an SEM image of the conventional 2219 laser remelted specimen, showing cracking.

[0067] FIG. 5e is an SEM image of the experimental 2219 laser remelted specimen, showing no cracking.

[0068] FIG. 6a is an EBSD image of a laser remelted specimen of conventional alloy 2219 (conventional composition).

[0069] FIG. 6b is an EBSD image of a laser remelted specimen of an experimental version of alloy 2219 (experimental composition having an additional 1 wt. % Zr (approx.)).

[0070] FIG. 6c is an EBSD image of a laser remelted specimen of an experimental version of conventional alloy 2219 (experimental composition having an additional 1 wt. % Zr (approx.)).

[0071] FIG. 7a is an EBSD image of a laser remelted specimen of conventional alloy 7050 (conventional composition).

[0072] FIG. 7b is an EBSD image of a laser remelted specimen of an experimental version of alloy 7050 (experimental composition having an additional 1 wt. % Zr (approx.)). DETAILED DESCRIPTION

[0073] Example 1

[0074] Several versions of alloys 2219 and 7050 were cast as book mold ingots, both with and without grain refiner precursors. A portion of each book mold ingot was then re-melted and solidified to simulate an additive manufacturing process. After the re-melting, metallographic images of the re-melted portion were prepared and visually analyzed for cracking.

i. Alloy 2219

[0075] Metallographic images of the re-melted portion of commercial alloy 2219 (Alloy 1) and an experimental version of aluminum alloy 2219 (Alloy 2) are shown in FIGs. 5a-5e. Alloy 2 was prepared as a book mold ingot by casting the 2219 aluminum alloy composition with an additional 2 wt. % Ti (approximately) as a grain refiner precursor. The composition was cast such that the titanium was homogenously mixed within the alloy. The grain structure of the re-melted portion of Alloy 1 is shown in FIGS. 5a and 5d. In this regard, FIG. 5a shows Alloy 1 realized a columnar grain structure. Further, Alloy 1 exhibited cracking as shown in FIG. 5d. Conversely, Alloy 2 realized an equiaxed grain structure as shown in FIGS. 5b and 5c. FIG. 5c shows homogenously distributed Al₃Ti particles having an approximate size of 20-500 nm in the micro structure. While not being bound by any theory, the AF,Ti particles are believed to have formed first from the melt during solidification (i.e., the AF,Ti particles are primary particles) to facilitate the formation of the equiaxed grains. The equiaxed grains are estimated to have an average grain size of around 1-4 micrometers. As shown in FIG. 5e, the re-melted portion of Alloy 2 was crack-free. While not being bound by any theory, it is believed that the AhTi particles facilitated the production of the crack-free microstructure (e.g., via the formation of equiaxed grains).

[0076] Metallographic images of the re-melted portion of commercial alloy 2219 (Alloy 3) and an additional experimental version of aluminum alloy 2219 (Alloy 4) are shown in FIGs. 6a-6c. Alloy 4 was prepared as a book mold ingot by casting the 2219 aluminum alloy composition with an additional 1 wt. % Zr (approximately) as a grain refiner precursor. The composition was cast such that the zirconium was homogenously mixed within the alloy. The conventional alloy without the additional zirconium realized a coarse grain structure (FIG. 6a). Conversely, as shown in FIG. 6b, Alloy 4 with 1 wt. % Zr as the grain refiner precursor realized an equiaxed grain structure and was free of cracks. While not being bound by any theory, it is believed that a homogenous distribution of AhZr particles (not shown) formed first from the melt during solidification to facilitate the formation of the equiaxed grains. Further, it is believed that the Al₃Zr particles facilitated the production of the crack- free microstructure (e.g., via the formation of equiaxed grains). As shown in FIG. 6c, the re- melted portion realized a generally equiaxed grain structure.

ii. Aluminum Alloy 7050 (Alloys 5-6)

[0077] Metallographic images of the re-melted portion of commercial alloy 7050 (Alloy 5) and an additional experimental version of aluminum alloy 7050 (Alloy 6) are shown in FIGs. 7a- 7b. Alloy 6 was prepared as a book mold ingot by casting the 7050 aluminum alloy composition with 1 wt. % Zr (approximately) as a grain refiner precursor. The composition was cast such that the zirconium was homogenously mixed within the alloy. In this regard, FIG. 7a shows Alloy 5 realized a coarse grain structure. Further, as also shown in FIG. 7a, Alloy 5 exhibited cracking. Conversely, as shown in FIG. 7b, Alloy 6 realized an equiaxed grain structure that was free of cracks. While not being bound by any theory, it is believed that a homogenous distribution of Al₃Zr particles (not shown) formed first from the melt during solidification to facilitate the formation of the equiaxed grains. Further, it is believed that the Al₃Zr particles facilitated the production of the crack-free microstructure (e.g., via the formation of equiaxed grains).

[0078] While various embodiments of the present disclosure have been described in detail, it is apparent that modifications and adaptations of those embodiments will occur to those skilled in the art. However, it is to be expressly understood that such modifications and adaptations are within the spirit and scope of the present disclosure.

Claims

CLAIMS What is claimed is:

1. A method comprising:

(a) forming a molten liquid comprising an aluminum alloy and one or more grain refiner precursors;

wherein the aluminum alloy is one of a lxxx aluminum alloy, 2xxx aluminum alloy, 3xxx aluminum alloy, 6xxx aluminum alloy, 7xxx aluminum alloy, and 8xxx aluminum alloy;

(b) forming an additive manufacturing feedstock from the molten liquid, wherein the forming the additive manufacturing feedstock comprises:

(i) first cooling the molten liquid to a temperature below its liquidus;

wherein the first cooling comprises reacting aluminum with the one or more grain refiner precursors to form one or more aluminum-containing grain refiners;

(ii) second cooling the molten liquid to a temperature below its solidus; and wherein the additive manufacturing feedstock comprises a homogenous distribution of the one or more aluminum-containing grain refiners within an aluminum alloy matrix of the additive manufacturing feedstock.

2. The method of claim 1, comprising:

(c) using the additive manufacturing feedstock to produce an additively manufactured product;

(i) wherein, at least partially due to the one or more aluminum-containing grain refiners, the additively manufactured product is crack-free.

3. A method comprising:

(a) forming, in an additive manufacturing apparatus, a molten liquid in the form of a melt pool, wherein the molten liquid comprises an aluminum alloy and one or more grain refiner precursors;

(b) first cooling the molten liquid to a temperature below its liquidus;

wherein the first cooling comprises reacting aluminum with the one or more grain refiner precursors to form one or more aluminum-containing grain refiners; (c) second cooling the molten liquid to a temperature below its solidus, thereby forming at least a portion of an additively manufactured product, wherein the portion of the additively manufactured product comprises a homogenous distribution of the one or more aluminum-containing grain refiners within an aluminum alloy matrix of the portion of the additively manufactured product;

wherein at least partially due to the one or more aluminum-containing grain refiners, the additively manufactured product is crack-free.

4. The method of claim 3, comprising:

during at least one of the first cooling step (b) and the second cooling step (c), nucleating one or more grains of the additively manufactured product via the one or more aluminum-containing grain refiners.

5. The method of claim 4, wherein at least partially due to the nucleating, in-situ grain refining is accomplished.

6. The method of any of the preceding claims, wherein the aluminum alloy is a crack-prone aluminum alloy.

7. The method of any of the preceding claims, wherein the method comprises:

determining which aluminum alloys of a group of aluminum alloys are crack-prone; wherein the aluminum alloy comprises a crack-prone aluminum alloy selected from the group of crack-prone aluminum alloys.

8. The method of claim 7, wherein the method comprises:

determining an amount of the one or more grain refiner precursors to utilize in the crack-prone aluminum alloy such that a crack-free additively manufactured version of the crack-prone aluminum alloy may be produced;

wherein the one or more grain refiner precursors comprise the determined amount of grain refiner precursors.

9. The method of any of the preceding claims, wherein the forming the molten liquid comprises:

dissolving the one or more grain refiner precursors in the molten liquid.

10. The method of any of the preceding claims, wherein the forming a molten liquid comprises:

forming a molten liquid comprising the aluminum alloy, the one or more grain refiner precursors, and one or more non-aluminum grain refiners.

11. The method of claim 10, wherein, at least partially due to the one or more aluminum- containing grain refiners and the one or more non-aluminum grain refiners, the additively manufactured product is crack-free.

12. A crack-free additively manufactured aluminum alloy product; wherein the crack-free additively manufactured aluminum alloy product comprises one of a lxxx, 2xxx, 3xxx, 6xxx, 7xxx, and 8xxx aluminum alloy; wherein the crack-free additively manufactured aluminum alloy product comprises at least one aluminum-containing grain refiner; wherein the crack- free additively manufactured aluminum alloy product comprises at least 0.275 wt. % of the aluminum-containing grain refiner.

13. The crack-free additively manufactured aluminum alloy product of claim 12, wherein the crack-free additively manufactured aluminum alloy product comprises at least 0.35 wt. % of the aluminum-containing grain refiners, or at least 0.5 wt. % of the aluminum-containing grain refiners, or at least 0.8 wt. % of the aluminum-containing grain refiners, or at least 1.0 wt. % of the aluminum-containing grain refiners, or at least 1.2 wt. % of the aluminum- containing grain refiners, or at least 1.4 wt. % of the aluminum-containing grain refiners, or at least 1.6 wt. % of the aluminum-containing grain refiners, or at least 1.8 wt. % of the aluminum-containing grain refiners, or at least 2.0 wt. % of the aluminum-containing grain refiners, or at least 2.2 wt. % of the aluminum-containing grain refiners, or at least 2.4 wt. % of the aluminum-containing grain refiners, or at least 2.6 wt. % of the aluminum-containing grain refiners, or at least 2.8 wt. % of the aluminum-containing grain refiners, or at least 3.0 wt. % of the aluminum-containing grain refiners, or at least 3.25 wt. % of the aluminum- containing grain refiners, or at least 3.5 wt. % of the aluminum-containing grain refiners, or at least 3.75 wt. % of the aluminum-containing grain refiners, or at least 4.0 wt. % of the aluminum-containing grain refiners, or at least 4.25 wt. % of the aluminum-containing grain refiners, or at least 4.5 wt. % of the aluminum-containing grain refiners, or at least 4.75 wt. % of the aluminum-containing grain refiners, or at least 5.0 wt. % of the aluminum-containing grain refiners, or at least 5.25 wt. % of the aluminum-containing grain refiners.

14. The crack-free additively manufactured aluminum alloy product of any of the preceding claims, wherein the aluminum alloy is a 2xxx aluminum alloy.

15. The crack-free additively manufactured aluminum alloy product of any of the preceding claims, wherein the aluminum alloy is a 6xxx aluminum alloy.

16. The crack-free additively manufactured aluminum alloy product of any of the preceding claims, wherein the aluminum alloy is a 7xxx aluminum alloy.

17. The crack-free additively manufactured aluminum alloy product of any of the preceding claims, wherein the aluminum alloy is a 8xxx aluminum alloy.

18. The crack-free additively manufactured aluminum alloy product of any of the preceding claims, wherein the aluminum-containing grain refiner comprises at least one of Al₃Ti, Al₃Zr and combinations thereof.

19. An automotive of aerospace component made from the additively manufactured product of any of claims 2-18.