WO2019191056A1

WO2019191056A1 - Additively manufactured aluminum alloy products having nanoscale grain refiners

Info

Publication number: WO2019191056A1
Application number: PCT/US2019/024018
Authority: WO
Inventors: Yijia GU; Lynette M. Karabin
Original assignee: Arconic Inc.
Priority date: 2018-03-29
Filing date: 2019-03-26
Publication date: 2019-10-03

Abstract

New additively manufactured aluminum alloy products having nanoscale grain refiners and methods for making the same are disclosed. The new additively manufactured aluminum alloy products may include an aluminum alloy matrix having an fcc crystalline microstructure and grain refiner particles dispersed within the aluminum alloy matrix. The grain refiner particles may have an average particle size of not greater than 500 nanometers and an area density of at least 0.0008 nanoscale grain refiner particle per 64 square micrometers. Further, the additively manufactured aluminum alloy products may include at least 50 vol. % of equiaxed grains having an area weighted average grain size of not greater than 50 micrometers.

Description

ADDITIVELY MANUFACTURED AUUMINUM AUUOY PRODUCTS HAVING

NANOSCAUE GRAIN REFINERS

FIEUD OF THE INVENTION

[001] This patent application relates to methods of additively manufacturing aluminum alloy products using nanoscale grain refiners, and additively aluminum alloy products made from the same.

BACKGROUND

[002] Additive manufacturing is defined as“a process of joining materials to make objects from 3D model data, usually layer upon layer, as opposed to subtractive manufacturing methodologies”, in ASTM F2792-l2a entitled “Standard Terminology for Additively Manufacturing Technologies.” Cracking of additively manufactured metal alloy products is a problem. See, e.g., Martin, John H. et al.“3D printing of high-strength aluminium alloys,” Nature volume 549, pages 365-369 (21 September 2017).

SUMMARY

[003] Broadly, the patent application relates to methods of additively manufacturing aluminum alloy products using nanoscale grain refiners, and additively manufactured aluminum alloy products made from the same. As used herein,“nanoscale” means materials having an average size of less than 1 micron, and generally 500 nanometers or less. It has been surprisingly found that nanoscale grain refiner particles are effective in producing additively manufactured aluminum alloy products having, for instance, one or more of equiaxed grains and/or crack-free additive manufacturing products, among others. Such products may also employ less grain refiner materials as compared to conventional additive manufacturing processes employing conventional grain refiner materials. These and other aspects of the new additively manufactured aluminum alloy products, including microstructure, compositions, methods of additive manufacturing, product applications and properties, are described in further detail below. i. Microstructure

[004] In one approach, an additively manufactured product comprises an aluminum alloy matrix having an fee crystalline microstructure and grain refiner particles. The grain refiner particles may be dispersed within the aluminum alloy matrix. In one embodiment, the nanoscale grain refiner particles have an average particle size of less than 1 micrometer, such as an average particle size of not greater than 500 nanometers. In one embodiment, an area density of the nanoscale grain refiner particles within the aluminum alloy matrix is at least 0.0008 nanoscale grain refiner particle per 64 square micrometers of the aluminum alloy matrix. Due to at least the size and density of these nanoscale grain refiner particles, an additively manufactured aluminum alloy product with a high amount of equiaxed grains in the as-built condition may be produced. In one embodiment, an additively manufactured aluminum alloy product comprises grains and at least 50 vol. % of the grains are equiaxed grains. In one embodiment, the equiaxed grains have an average size of not greater than 50 micrometers (e.g., not greater than 10 micrometers).

a. Nanoscale Grain Refiner Particles

[005] As noted above, the new additively manufactured aluminum alloy products may include nanoscale grain refiner particles. As used herein,“nanoscale grain refiner particles” means grain refiners particles having a size of less than 1 micrometers.

[006] As used herein,“grain refiner” means a nucleant or nucleants that facilitates alloy matrix crystal formation (e.g., fee crystals/grains). Suitable grain refiners include ceramic materials, intermetallic particles, and combinations thereof, among others.

[007] In one embodiment, the average particle size of the nanoscale grain refiner particles is not greater than 500 nanometers. In another embodiment, the average particle size of the nanoscale grain refiner particles is not greater than 400 nanometers. In yet another embodiment, the average particle size of the nanoscale grain refiner particles is not greater than 350 nanometers. In another embodiment, the average particle size of the nanoscale grain refiner particles is not greater than 300 nanometers. In yet another embodiment, the average particle size of the nanoscale grain refiner particles is not greater than 250 nanometers. In another embodiment, the average particle size of the nanoscale grain refiner particles is not greater than 200 nanometers. In yet another embodiment, the average particle size of the nanoscale grain refiner particles is not greater than 175 nanometers. In another embodiment, the average particle size of the nanoscale grain refiner particles is not greater than 150 nanometers. In yet another embodiment, the average particle size of the nanoscale grain refiner particles is not greater than 125 nanometers. In another embodiment, the average particle size of the nanoscale grain refiner particles is not greater than 100 nanometers, or less.

[008] In one embodiment, the average particle size of the nanoscale grain refiner particles is at least 1 nanometers. In another embodiment, the average particle size of the nanoscale grain refiner particles is at least 5 nanometers. In yet another embodiment, the average particle size of the nanoscale grain refiner particles is at least 7.5 nanometers. In another embodiment, the average particle size of the nanoscale grain refiner particles is at least 10 nanometers. In yet another embodiment, the average particle size of the nanoscale grain refiner particles is at least 15 nanometers. In another embodiment, the average particle size of the nanoscale grain refiner particles is at least 20 nanometers. In yet another embodiment, the average particle size of the nanoscale grain refiner particles is at least 30 nanometers. In another embodiment, the average particle size of the nanoscale grain refiner particles is at least 40 nanometers. In yet another embodiment, the average particle size of the nanoscale grain refiner particles is at least 50 nanometers. In another embodiment, the average particle size of the nanoscale grain refiner particles is at least 60 nanometers. In yet another embodiment, the average particle size of the nanoscale grain refiner particles is at least 70 nanometers. In another embodiment, the average particle size of the nanoscale grain refiner particles is at least 80 nanometers. In yet another embodiment, the average particle size of the nanoscale grain refiner particles is at least 90 nanometers, or higher. Any of the average particle size upper limits of the nanoscale grain refiner particles described in the preceding paragraph may be combined with any of the lower average particle size limits of the nanoscale grain refiner particles described in this paragraph.

[009] In some embodiments, an additively manufactured aluminum alloy product has a grain size of from about 1 micrometer to about 10 micrometers. Some non-limiting examples of embodiments of aluminum alloys having amounts of nanoscale grain refiner particles for such additively manufactured aluminum alloy products are given in Table 1, below.

Table 1: Non-Limiting, Example Grain Refiner Content

[0010] As shown, in some embodiments, the new aluminum alloys described herein may have, for instance, from 0.0008 to 44 nanoscale grain refiner particles per 64 square micrometers and may have an average grain size of from about 1 micrometer to about 10 micrometers. As shown, in some embodiments, the new aluminum alloys described herein may have, for instance, from about 1.0 x 1 O ⁷ to about 14 volume percent of nanoscale grain refiner particles and may have an average grain size of from about 1 micrometer to about 10 micrometers.

[001 1] In some embodiments, an area density of the nanoscale grain refiner particles within the aluminum alloy matrix is at least 0.0008 nanoscale grain refiner particle per 64 square micrometers of the aluminum alloy matrix. In one embodiment, an area density of the nanoscale grain refiner particles within the aluminum alloy matrix is at least 0.01 nanoscale grain refiner particle per 64 square micrometers of the aluminum alloy matrix. In another embodiment, an area density of the nanoscale grain refiner particles within the aluminum alloy matrix is at least 0.1 nanoscale grain refiner particle per 64 square micrometers of the aluminum alloy matrix. In yet another embodiment, an area density of the nanoscale grain refiner particles within the aluminum alloy matrix is at least 1 nanoscale grain refiner particle per 64 square micrometers of the aluminum alloy matrix. In some embodiments, an area density of the nanoscale grain refiner particles within the aluminum alloy matrix is not greater than 44 nanoscale grain refiner particles per 64 square micrometers of the aluminum alloy matrix. In one embodiment, an area density of the nanoscale grain refiner particles within the aluminum alloy matrix is not greater than 30 nanoscale grain refiner particles per 64 square micrometers of the aluminum alloy matrix. In another embodiment, an area density of the nanoscale grain refiner particles within the aluminum alloy matrix is not greater than 17 nanoscale grain refiner particles per 64 square micrometers of the aluminum alloy matrix.

[0012] In some embodiments, an aluminum alloy comprises at least 1 x 10 ⁷ vol. % nanoscale particles. In another embodiment, an aluminum alloy comprises at least 0.0001 vol. % nanoscale particles. In another embodiment, an aluminum alloy comprises at least 0.001 vol. % nanoscale particles. In yet another embodiment, an aluminum alloy comprises at least 0.01 vol. % nanoscale particles. In some embodiments, an aluminum alloy comprises not greater than 14 vol. % nanoscale particles. In one embodiment, an aluminum alloy comprises not greater than 10 vol. % nanoscale particles. In another embodiment, an aluminum alloy comprises not greater than 5 vol. % nanoscale particles. In yet another embodiment, an aluminum alloy comprises not greater than 1 vol. % nanoscale particles.

[0013] The average particle size, area density and/or volumetric percentage of the nanoscale grain refiner particles may be determined via an SEM image analysis of a suitable number of SEM micrographs of the additively manufactured product in the as-built condition. Generally, at least 5 micrographs (e.g., at least 10 micrographs) should be analyzed. 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.

[0014] As noted above, the nanoscale grain refiner particles are generally distributed within the aluminum alloy matrix. In one embodiment, the nanoscale grain refiner particles are homogenously distributed within the aluminum alloy matrix. In other embodiments, the nanoscale grain refiner particles are non-homogenously distributed relative to the aluminum alloy matrix.

[0015] As noted above, the nanoscale grain refiner particles may comprise one or more ceramic materials. Examples of 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, T1B2, TiC, SiC, AI2O3, BC, BN, S13N4, AI4C3, A1N, their suitable equivalents, and/or combinations thereof.

[0016] As noted above, the nanoscale grain refiner particles may comprise one or more intermetallic particles. For instance, the aluminum alloy compositions described herein may include materials that may facilitate the formation of intermetallic particles (e.g., during solidification). In this regard, non-limiting examples of such materials that may be used include titanium, zirconium, scandium, hafnium, vanadium, molybdenum, niobium, tantalum and tungsten, optionally in elemental form, among others. b. Equiaxed Grains

[0017] As noted above, employing a suitable number density of nanoscale grain refiner particles may facilitate production of additively manufactured aluminum alloy products having a high amount of equiaxed grains in the as-built condition. In one embodiment, an additively manufactured aluminum alloy product in the as-built condition comprises grains and at least 50 vol. % of the grains are equiaxed grains. In another embodiment, an additively manufactured aluminum alloy product in the as-built condition comprises at least 60 vol. % of equiaxed grains. In yet another embodiment, an additively manufactured aluminum alloy product in the as-built condition comprises at least 70 vol. % of equiaxed grains. In another embodiment, an additively manufactured aluminum alloy product in the as-built condition comprises at least 80 vol. % of equiaxed grains. In yet another embodiment, an additively manufactured aluminum alloy product in the as-built condition comprises at least 90 vol. % of equiaxed grains. In another embodiment, an additively manufactured aluminum alloy product in the as-built condition comprises at least 95 vol. % of equiaxed grains. In yet another embodiment, an additively manufactured aluminum alloy product in the as-built condition comprises at least 99 vol. % of equiaxed grains, or more.

[0018] The area weighted average grain 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 area weighted average grain 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 area weighted average grain 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 area weighted average grain 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 area weighted average grain 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 area weighted average grain 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 area weighted average grain 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 area weighted average grain 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 area weighted average grain 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] 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”.

[0020] As used herein, the“grain size” is calculated by the following equation:

4Ai

vz = square root (— )

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

• wherein vz 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.

[0021] As used herein, the“area weighted average grain size” is calculated by the following equation:

v-bar

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

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

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

[0022] 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. ii. Composition

[0023 ] The new additively manufactured aluminum alloy products may be made from any suitable aluminum alloy composition. In one embodiment, the aluminum alloy is one of a lxxx, 2xxx, 3xxx, 4xxx, 5xxx, 6xxx, 7xxx, and 8xxx aluminum alloy, as defined by the Aluminum Association document ANSI H35.1 entitled,“American National Standard Alloy and Temper Designation Systems for Aluminum” (2009), pages 4-5, modified to have the nanoscale grain refiners disclosed herein. In another embodiment, the aluminum alloy is one of a lxx, 2xx, 3xx, 4xx, 5xx, 7xx, 8xx and 9xx aluminum casting and ingot alloy, as defined by the Aluminum Association document ANSI H35.1 entitled,“American National Standard Alloy and Temper Designation Systems for Aluminum” (2009), pages 6-7, modified to have the nanoscale grain refiners disclosed herein. In one embodiment, the aluminum alloy is one of a lxxx, 2xxx, 3xxx, 4xxx, 5xxx, 6xxx, 7xxx and 8xxx aluminum alloy composition of the Aluminum Association document “International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys” (2015) (a.k.a., the“Teal Sheets”), modified to have the nanoscale grain refiners disclosed herein. In another embodiment, the aluminum alloy is one of a lxx, 2xx, 3xx, 4xx, 5xx, 7xx, 8xx and 9xx aluminum alloy composition of 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”), modified to have the nanoscale grain refiners disclosed herein. iii. Additive Manufacturing

a. Addi tive Manufacturing Processes

[0024] As used herein,“additive manufacturing” means“a process of j oining 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.” The additively manufactured aluminum alloy products described herein may be manufactured via any appropriate additive manufacturing technique described in this ASTM standard, such as binder jetting, directed energy deposition, material extrusion, material jetting, powder bed fusion, or sheet lamination, among others. Non-limiting examples of additive manufacturing processes useful in producing additively manufactured 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.

[0025] Additive manufacturing techniques may facilitate the selective heating of additive manufacturing feedstock(s) above the liquidus temperature of the particular aluminum alloy to be formed, thereby forming a molten pool, followed by rapid solidification of the molten pool. For instance, in one embodiment, a method comprises (a) selectively heating at least a portion of an additive manufacturing feedstock (e.g., via a laser) to a temperature above the liquidus temperature of the particular aluminum alloy to be formed, (b) forming a molten pool, and (c) cooling the molten pool to form a solidified mass. Steps (a)-(c) may be repeated as necessary until the additively manufactured alloy product is completed.

[0026] In one embodiment, an additive manufacturing process includes depositing successive layers of one or more powders and then selectively melting and/or sintering the powders to create, layer-by-layer, an additively manufactured aluminum alloy product. In one embodiment, a method comprises (a) dispersing a powder in a bed, (b) selectively heating a portion of the powder (e.g., via a laser) to a temperature above the liquidus temperature of the particular aluminum alloy product to be formed, (c) forming a molten pool and (d) cooling the molten pool to form a solidified mass. Steps (a)-(c) may be repeated as necessary until the additively manufactured alloy product is completed.

[0027] In one embodiment, an additive manufacturing process uses an EOSINT M 280 Direct Metal Laser Sintering (DMLS) additive manufacturing system, or comparable system, available from EOS GmbH (Robert-Stirling-Ring 1, 82152 Krailling/Munich, Germany). [0028] In one embodiment, a method comprises (a) dispersing a powder in a bed, (b) selectively binder jetting the powder, and repeating steps (a)-(b), as appropriate, until a green additively manufactured part is completed. The green additively manufactured part may be further processed, such as by sintering and/or hot isostatic pressing (“HIP’ing”).

[0029] In one embodiment, directed energy deposition techniques are utilized. In one embodiment, a method comprises spraying one or more additive manufacturing feedstock powders in a controlled environment, and concomitant to the spraying, a laser is used to melt and/or solidify the sprayed additive manufacturing feedstock powder(s). This spraying and concomitant energy deposition may be repeated, as necessary to facilitate production of an additively manufactured aluminum alloy product.

[0030] In one embodiment, electron beam (EB) or plasma arc techniques are utilized. Electron beam techniques may facilitate production of larger parts than readily produced via laser additive manufacturing techniques. For instance, in one embodiment, a method comprises feeding a wire (e.g., < 2.54 mm in diameter) to the wire feeder portion of an electron beam gun. The wire may comprise any of the alloys described above. The electron beam heats the wire or tube, as the case may be, above the liquidus point of the alloy to be formed, followed by rapid solidification of the molten pool to form the deposited material.

[0031 ] In one or more of the described embodiments, the cooling the molten pool comprises cooling at a cooling rate of at least l000°C per second. In one or more of the described embodiments, the cooling the molten pool comprises cooling at a cooling rate of at least l0,000°C per second. In one or more of the described embodiments, the cooling the molten pool comprises cooling at a cooling rate of at least l00,000°C per second. In one or more of the described embodiments, the cooling the molten pool comprises cooling at a cooling rate of at least l,000,000°C per second.

[0032] Due to the amount and size of the nanoscale grain refiner particles, crack-free aluminum alloy products in the as-built condition may be produced and realized. 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 an ultrasonic inspection. 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 El 441. 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.

b. Additive Manufacturing Feedstocks

[0033 ] The additive manufacturing processes described above may employ any suitable feedstock, including one or more powders, one or more wires, one or more sheets, and combinations thereof.

[0034] In some embodiments the additive manufacturing feedstock is comprised of one or more powders. Powders for use in additive manufacturing may be produced with or without the nanoscale grain refiner particles therein. For instance, an additive manufacturing powder feedstock may be comprised of any combination of metallic powders, alloy powders, and non- metalbc powders (e.g., ceramic powders). For instance, any combination of metallic powders, alloy powders, and/or non-metallic powders may be used to realize an aluminum alloy composition described above. Furthermore, an additive manufacturing feedstock powder may comprise metallic powders and/or alloy powders, where the particles comprise the metallic powders and/or alloy particles having grain refining material therein (e.g., ceramic materials). By way of non-limiting example, an additive manufacturing feedstock powder may be comprised of alloy particles, and the alloy particles may include a plurality of non-metallic particles therein, wherein the non-metallic particles have a smaller size than the alloy particles. The applicable powders may be blended or used separately to make the additively manufactured aluminum alloy product.

[0035] As used herein,“powder” means a material comprising a plurality of particles suited to produce an aluminum alloy product via additive manufacturing. In the context of additive manufacturing powder feedstocks,“particle” means a minute fragment of matter having a size suitable for use in the powder of the powder bed (e.g., a size of from 5 microns to 100 microns). Shavings are types of particles. Suitable methods for producing powders include, for instance, atomization (e.g., gas atomization, plasma atomization), and impingement of a molten liquid (e.g., solidification of an impinging molten metal droplet on a cold substrate), among others.

[0036] In some embodiments, the additive manufacturing feedstock is comprised of one or more wires. A ribbon is a type of wire. The wires may be produced, for instance, via melt spinning to produce a ribbon. Powder cored wires may also be used (e.g., per commonly owned U.S. Patent Publications US20170014937A1 and/or US 20170120386A1).

[0037] In some embodiments, the additive manufacturing feedstock is comprised of one or more sheets. Foil is a type of sheet. Sheets may be used in additive manufacturing processes such as sheet lamination, per ASTM F2792-l2a.

c. Optional Post-Processing

[0038] After their production, the new additively manufactured aluminum alloys may be subjected to one or more deforming (e.g., working) steps and/or one or more thermally treating steps. Deforming may occur, for instance, before, after or during (e.g., concomitant to) any thermally treating steps.

[0039] In one embodiment, deforming an additively manufactured aluminum alloy product comprises hot isostatic pressing (“HIP’ing”). In another embodiment, deforming an additively manufactured aluminum alloy product comprises working. Working may include hot working and/or cold working. The working may include working all of the product, or a portion of the product. The working may include, for instance, rolling, extruding, forging, and other known methods of working aluminum alloy products. In one embodiment, the working comprises die forging the final additively manufactured product into the final worked product, wherein the final worked product is a complex shape (e.g., having a plurality of non-planar surfaces).

[0040] As noted above, the new additively manufactured aluminum alloy products may be thermally treated. Thermally treating an additively manufactured aluminum alloy may comprise one or more of solution heat treating and quenching, precipitation hardening (aging), and annealing.

[0041] The terms“solution heat treating” and the like (e.g.,“solutionizing”), means heating an alloy body to a suitable temperature, generally above a solvus temperature, and holding at that temperature long enough to allow at least some soluble element(s) to enter solid solution. Quenching may optionally be employed after a solution heat treatment. The quenching may comprise cooling rapidly enough to hold at least some dissolved element(s) in solid solution. The quenching may facilitate production of a supersaturated solid solution. A subsequent precipitation hardening step may facilitate the production of precipitate phases from a supersaturated solid solution, as discussed in greater detail below.

[0042] In one embodiment, thermally treating an aluminum alloy comprises precipitation hardening. A precipitation hardening step may be employed after production of an aluminum alloy product and/or after solution heat treating and quenching of an aluminum alloy product. For instance, an additively manufactured aluminum alloy product may realize a supersaturated solid solution in the as-built condition (e.g., due to high cooling rates of at least l000°C/s). Precipitation hardening of the new aluminum alloys may occur at room temperature (sometimes referred to as a“natural age”) and/or at one or more elevated temperatures (sometimes referred to as an“artificial age”). Certain aluminum alloys (e.g., 2xxx, 6xxx, 7xxx, 2xx, 3xx, and 7xx aluminum alloys) may be precipitation hardened (e.g., to increase strength). The precipitation hardening may be performed for a time sufficient and at a temperature sufficient to facilitate the production of one or more precipitates. Various combinations of (1) solution heat treating and quenching and (2) aging steps may be performed. For instance, an aluminum alloy may be processed to one of a Tl, T2, T3, T4, T6, T7, T8, T9 or T10 temper, as defined in ANSI H35.1 (2009). Any other tempers of ANSI H35.1 (2009), or others known in the art, may be utilized. For instance, the new additively manufactured aluminum alloy products may be processed to one of an H, F, O or W temper, among others. iv. Product Applications

[0043 ] The new additively manufactured aluminum alloy products described herein may be used in a variety of product applications. In one embodiment, a new additively manufactured aluminum alloy product is utilized in an elevated temperature application, such as in an aerospace (e.g. engines or structures), automotive vehicle (e.g. piston, valve, among others), defense, electronics (e.g. consumer electronics) or space application. In one embodiment, a new aluminum alloy product is used in a ground transportation application. In one embodiment, a new additively manufactured aluminum alloy product is utilized as an engine component in an aerospace vehicle (e.g., in the form of a blade, such as a compressor blade incorporated into the engine). In another embodiment, a new additively manufactured aluminum alloy product is used as a heat exchanger for the engine of the aerospace vehicle. The aerospace vehicle including the engine component / heat exchanger may subsequently be operated. In one embodiment, a new additively manufactured aluminum alloy product is an automotive engine component. The automotive vehicle including the engine component may subsequently be operated. For instance, a new additively manufactured aluminum alloy product may be used as a turbocharger component (e.g., a compressor wheel of a turbocharger, where elevated temperatures may be realized due to recycling engine exhaust back through the turbocharger), and the automotive vehicle including the turbocharger component may be operated. In another embodiment, anew additively manufactured aluminum alloy product may be used as a blade in a land based (stationary) turbine for electrical power generation, and the land based turbine included the aluminum product may be operated to facilitate electrical power generation.

[0044] In one aspect, the new additively manufactured aluminum alloy products may be utilized in a structural application. In one embodiment, a new additively manufactured aluminum alloy product is utilized in an aerospace structural application. For instance, the new additively manufactured aluminum alloy product may be formed into various aerospace structural components, including floor beams, seat rails, fuselage framing, bulkheads, spars, ribs, longerons, and brackets, among others. In another embodiment, the new additively manufactured aluminum alloy products are utilized in an automotive structural application. For instance, the new additively manufactured aluminum alloy products may be formed into various automotive structural components including nodes of space frames, shock towers, and subframes, among others.

[0045 ] In one aspect, the new additively manufactured aluminum alloy products 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.

[0046] Aside from the applications described above, the new additively manufactured aluminum alloy products 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 additively manufactured aluminum alloy products may be incorporated in goods including the likes of car panels, media players, bottles and cans, office supplies, packages and containers, among others. v. Properties

[0047] Due to the nanoscale grain refiner particles, the additively manufactured aluminum alloy products may realize an improved combination of properties over conventional additively manufactured aluminum alloy products. Conventional additively manufactured aluminum alloy products generally use grain refiners having an average size of more than 1 micrometers. In one embodiment, a new additively manufactured aluminum alloy product realizes an improved combination of at least two of strength, fracture toughness, corrosion resistance, fatigue resistance, and fatigue crack growth resistance as compared to a compositionally equivalent conventional additively manufactured aluminum alloy product having an average grain refiner particle size of greater than 1 micrometer. In another embodiment, a new additively manufactured aluminum alloy product realizes an improved combination of at least three of strength, fracture toughness, corrosion resistance, fatigue resistance, and fatigue crack growth resistance as compared to a compositionally equivalent conventional additively manufactured aluminum alloy product having an average grain refiner particle size of greater than 1 micrometer. In another embodiment, a new additively manufactured aluminum alloy product realizes an improved combination of at least four of strength, fracture toughness, corrosion resistance, fatigue resistance, and fatigue crack growth resistance as compared to a compositionally equivalent conventional additively manufactured aluminum alloy product having an average grain refiner particle size of greater than 1 micrometer. In another embodiment, a new additively manufactured aluminum alloy product realizes an improved combination of all of strength, fracture toughness, corrosion resistance, fatigue resistance, and fatigue crack growth resistance as compared to a compositionally equivalent conventional additively manufactured aluminum alloy product having an average grain refiner particle size of greater than 1 micrometer. vi. Miscellaneous

[0048] The figure constitutes a part of this specification and include illustrative embodiments of the present disclosure and illustrate various objects and features thereof. In addition, any measurements, specifications and the like shown in the figure are intended to be illustrative, and not restrictive. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.

[0049] Among those benefits and improvements that have been disclosed, other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying figure. Detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely illustrative of the invention that may be embodied in various forms. In addition, each of the examples given in connection with the various embodiments of the invention is intended to be illustrative, and not restrictive. [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 herein, 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.

BRIEF DESCRIPTION OF THE DRAWING

[0052] FIG. 1 is a micrograph of an aluminum alloy product having a nanoscale T1B2 grain refiner particle (10).

DETAILED DESCRIPTION

Example 1

[0053] An aluminum alloy was produced using additive manufacturing solidification conditions and using nanoscale T1B2 grain refiner particles. FIG. 1 shows a micrograph of the product. A nanoscale T1B2 particle (10) is circled. The TiB2 particle (10) has a size of about 20 nanometers and facilitated grain refinement.

[0054] Aspects of the invention will now be described with reference to the following numbered clauses:

Clause 1. An additively manufactured aluminum alloy product comprising:

(a) an aluminum alloy matrix having an fee crystalline microstructure;

(b) nanoscale grain refiner particles dispersed within the aluminum alloy matrix, wherein:

(i) the nanoscale grain refiner particles have an average particle size of not greater than 500 nanometers; (ii) an area density of the nanoscale grain refiner particles within the aluminum alloy matrix is at least 0.0008 nanoscale grain refiner particle per 64 square micrometers; and

wherein the additively manufactured aluminum alloy product comprises grains and wherein at least 50 vol. % of the grains are equiaxed grains, and wherein the equiaxed grains have an area weighted average grain size of not greater than 50 micrometers.

Clause 2. The additively manufactured aluminum alloy product of clause 1, wherein the nanoscale grain refiner particles have an average particle size of at least 1 nanometers, or at least 5 nanometers, or at least 7.5 nanometers, or at least 10 nanometers, or at least 15 nanometers, or at least 20 nanometers, or at least 30 nanometers, or at least 40 nanometers, or at least 50 nanometers, or at least 60 nanometers, or at least 70 nanometers, or at least 80 nanometers, or at least 90 nanometers.

Clause 3. The additively manufactured aluminum alloy product of any of the preceding clauses, wherein the nanoscale grain refiner particles have an average particle size of not greater than 400 nanometers, or not greater than 350 nanometers, or not greater than 300 nanometers, or not greater than 250 nanometers, or not greater than 200 nanometers, or not greater than 175 nanometers, or not greater than 150 nanometers, or not greater than 125 nanometers, or not greater than 100 nanometers.

Clause 4. The additively manufactured aluminum alloy product of any of the preceding clauses, wherein the area density of the nanoscale grain refiner particles within the aluminum alloy matrix is not greater than 44 nanoscale grain refiner particles per 64 square

micrometers, or not greater than 30 nanoscale grain refiner particles per 64 square micrometers, or not greater than 17 nanoscale grain refiner particles per 64 square micrometers.

Clause 5. The additively manufactured aluminum alloy product of any of the preceding clauses, wherein the area density of the nanoscale grain refiner particles within the aluminum alloy matrix is at least 0.01 nanoscale grain refiner particles per 64 square micrometers, or at least 0.1 nanoscale grain refiner particles per 64 square micrometers, or at least 1 nanoscale grain refiner particles per 64 square micrometers.

Clause 6. The additively manufactured aluminum alloy product of any of the preceding clauses, wherein a volumetric percentage of the nanoscale grain refiner particles within the aluminum alloy matrix is at least 0.0001, or at least 0.001, or at least 0.01. Clause 7. The additively manufactured aluminum alloy product of any of the preceding clauses, wherein a volumetric percentage of the nanoscale grain refiner particles within the aluminum alloy matrix is not greater than 10, or not greater than 5, or not greater than 1. Clause 8. The additively manufactured aluminum alloy product of any of the preceding clauses, wherein at least 60 vol. % of the grains are equiaxed grains, or at least 70 vol. % of the grains are equiaxed grains, or at least 80 vol. % of the grains are equiaxed grains, or at least 90 vol. % of the grains are equiaxed grains, or at least 95 vol. % of the grains are equiaxed grains, or at least 99 vol. % of the grains are equiaxed grains.

Clause 9. The additively manufactured aluminum alloy product of any of the preceding clauses, wherein the equiaxed grains have an area weighted average grain size of not greater than 40 microns, or not greater than 30 microns, or not greater than 20 microns, or not greater than 10 microns, or not greater than 5 microns, or not greater than 4 microns, or not greater than 3 microns, or not greater than 2 microns.

Clause 10. The additively manufactured aluminum alloy product of any of the preceding clauses, wherein the equiaxed grains have an average aspect ratio not greater than 4: 1, or not greater than 3 : 1 , or not greater than 2 : 1 , or not greater than 1.5 : 1 , or not greater than 1.1: 1. Clause 11. The additively manufactured aluminum alloy product of any of the preceding clauses, wherein the nanoscale grain refiner particles comprise at least one of ceramic materials and intermetallic particles.

Clause 12. The additively manufactured aluminum alloy product of clause 11, wherein the nanoscale grain refiner particles comprise at least ceramic materials, and wherein the ceramic materials comprise oxide materials, boride materials, carbide materials, nitride materials, silicon materials, carbon materials, and combinations thereof.

Clause 13. The additively manufactured aluminum alloy product of clause 12, wherein the ceramic materials comprise at least one of TiB, T1B2, TiC, SiC, AI2O3, BC, BN, S13N4, AI4C3, and A1N.

Clause 14. The additively manufactured aluminum alloy product of clause 13, wherein the ceramic materials comprise at least T1B2.

Clause 15. The additively manufactured aluminum alloy product of clause 11, wherein the nanoscale grain refiner particles at least comprise intermetallic particles, and wherein the intermetallic particles comprise at least one of titanium, zirconium, scandium, hafnium, vanadium, molybdenum, niobium, tantalum and tungsten. Clause 16. The additively manufactured aluminum alloy product of any of the preceding clauses, wherein the nanoscale grain refiner particles are homogenously distributed throughout the aluminum alloy matrix.

Clause 17. The additively manufactured aluminum alloy product of any of the preceding clauses, wherein the additively manufactured aluminum alloy product is in an as-built condition.

Clause 18. The additively manufactured aluminum alloy product of any of the preceding clauses, wherein the additively manufactured aluminum alloy product is crack-free.

Clause 19. The additively manufactured aluminum alloy product of any of the preceding clauses, wherein the additively manufactured aluminum alloy product realizes an improved combination of at least two of strength, fracture toughness, corrosion resistance, fatigue resistance, and fatigue crack growth resistance, as compared to a compositionally equivalent conventional additively manufactured aluminum alloy product, wherein the compositionally equivalent conventional additively manufactured aluminum alloy product has grain refiner particles having an average size of more than 1 micrometers.

[0055] Other clauses based on any of the above paragraphs of the specification and the attached drawings are contemplated and apply to the present patent application.

[0056] 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.

Claims

CLAIMS What is claimed is:

1. An additively manufactured aluminum alloy product comprising:

(a) an aluminum alloy matrix having an fee crystalline microstructure;

(i) the nanoscale grain refiner particles have an average particle size of not greater than 500 nanometers;

(ii) an area density of the nanoscale grain refiner particles within the aluminum alloy matrix is at least 0.0008 nanoscale grain refiner particle per 64 square micrometers; and

2. The additively manufactured aluminum alloy product of claim 1, wherein the nanoscale grain refiner particles have an average particle size of at least 1 nanometers, or at least 5 nanometers, or at least 7.5 nanometers, or at least 10 nanometers, or at least 15 nanometers, or at least 20 nanometers, or at least 30 nanometers, or at least 40 nanometers, or at least 50 nanometers, or at least 60 nanometers, or at least 70 nanometers, or at least 80 nanometers, or at least 90 nanometers.

3. The additively manufactured aluminum alloy product of claim 1, wherein the nanoscale grain refiner particles have an average particle size of not greater than 400 nanometers, or not greater than 350 nanometers, or not greater than 300 nanometers, or not greater than 250 nanometers, or not greater than 200 nanometers, or not greater than 175 nanometers, or not greater than 150 nanometers, or not greater than 125 nanometers, or not greater than 100 nanometers.

4. The additively manufactured aluminum alloy product of claim 1, wherein the area density of the nanoscale grain refiner particles within the aluminum alloy matrix is not greater than 44 nanoscale grain refiner particles per 64 square micrometers, or not greater than 30 nanoscale grain refiner particles per 64 square micrometers, or not greater than 17 nanoscale grain refiner particles per 64 square micrometers.

5. The additively manufactured aluminum alloy product of claim 4, wherein the area density of the nanoscale grain refiner particles within the aluminum alloy matrix is at least 0.01 nanoscale grain refiner particles per 64 square micrometers, or at least 0.1 nanoscale grain refiner particles per 64 square micrometers, or at least 1 nanoscale grain refiner particles per 64 square micrometers.

6. The additively manufactured aluminum alloy product of claim 1, wherein a volumetric percentage of the nanoscale grain refiner particles within the aluminum alloy matrix is at least 0.0001, or at least 0.001, or at least 0.01.

7. The additively manufactured aluminum alloy product of claim 6, wherein a volumetric percentage of the nanoscale grain refiner particles within the aluminum alloy matrix is not greater than 10, or not greater than 5, or not greater than 1.

8. The additively manufactured aluminum alloy product of claim 1, wherein at least 60 vol.

% of the grains are equiaxed grains, or at least 70 vol. % of the grains are equiaxed grains, or at least 80 vol. % of the grains are equiaxed grains, or at least 90 vol. % of the grains are equiaxed grains, or at least 95 vol. % of the grains are equiaxed grains, or at least 99 vol. % of the grains are equiaxed grains.

9. The additively manufactured aluminum alloy product of claim 8, wherein the equiaxed grains have an area weighted average grain size of not greater than 40 microns, or not greater than 30 microns, or not greater than 20 microns, or not greater than 10 microns, or not greater than 5 microns, or not greater than 4 microns, or not greater than 3 microns, or not greater than 2 microns.

10. The additively manufactured aluminum alloy product of claim 1, wherein the equiaxed grains have an average aspect ratio not greater than 4 : 1 , or not greater than 3 : 1 , or not greater than 2 : 1 , or not greater than 1.5 : 1 , or not greater than 1.1: 1.

11. The additively manufactured aluminum alloy product of claim 1, wherein the nanoscale grain refiner particles comprise at least one of ceramic materials and intermetallic particles.

12. The additively manufactured aluminum alloy product of claim 11, wherein the nanoscale grain refiner particles comprise at least ceramic materials, and wherein the ceramic materials comprise oxide materials, boride materials, carbide materials, nitride materials, silicon materials, carbon materials, and combinations thereof.

13. The additively manufactured aluminum alloy product of claim 12, wherein the ceramic materials comprise at least one of TiB, T1B2, TiC, SiC, AI2O3, BC, BN, S13N4, AI4C3, and A1N.

14. The additively manufactured aluminum alloy product of claim 13, wherein the ceramic materials comprise at least T1B2.

15. The additively manufactured aluminum alloy product of claim 11, wherein the nanoscale grain refiner particles at least comprise intermetallic particles, and wherein the intermetallic particles comprise at least one of titanium, zirconium, scandium, hafnium, vanadium, molybdenum, niobium, tantalum and tungsten.

16. The additively manufactured aluminum alloy product of claim 1, wherein the nanoscale grain refiner particles are homogenously distributed throughout the aluminum alloy matrix.

17. The additively manufactured aluminum alloy product of claim 1, wherein the additively manufactured aluminum alloy product is in an as-built condition.

18. The additively manufactured aluminum alloy product of claim 1 or 17, wherein the additively manufactured aluminum alloy product is crack-free.

19. The additively manufactured aluminum alloy product of claim 1, wherein the additively manufactured aluminum alloy product realizes an improved combination of at least two of strength, fracture toughness, corrosion resistance, fatigue resistance, and fatigue crack growth resistance, as compared to a compositionally equivalent conventional additively

manufactured aluminum alloy product, wherein the compositionally equivalent conventional additively manufactured aluminum alloy product has grain refiner particles having an average size of more than 1 micrometers.