POWDER PRETREATMENT PROCESS FOR ADDITIVE MANUFACTURING

Abstract

A method of processing a powder starting material (21) including a plurality of particles to form a product, the product having a plurality of grains with a nominal grain size, the method comprising: Atomizing a base material to produce the powder material; Heat treating a powder material at a temperature in the range up to 1400°C for a period of up to 100 hours to form the powder starting material (21), wherein the plurality of particles of the powder starting material (21) includes a collection of phase particles arranged in a matrix material, the collection of phase particles having a first nominal size distribution, wherein heat treating the powder material to form the powder starting material (21) comprises nucleating the phase within the powder material and growing a phase within the powder material to form the collection of phase particles; wherein the matrix material comprises one of the following: an Al-based alloy, a Co-based alloy, an Fe-based alloy, a Ni-based alloy and a Ti-based alloy, wherein the collection of phase particles comprises one or more of the following: carbides, borides, nitrides, oxides, intermetallics and topographically close packed (TCP) phases, Forming a solid component (28) from the powder starting material (21) in an additive manufacturing process; and Producing the article of manufacture from the solid component (28), wherein the first nominal size distribution of the collection of phase particles is such that at least a portion of the collection of phase particles persists throughout the additive manufacturing process and is present as a processed collection of phase particles in the solid component (28), and wherein the processed collection of phase particles has a second nominal size distribution effective to produce the nominal grain size of the article of manufacture.

Description

BACKGROUND

[0001] The field of the disclosure relates generally to additive manufacturing systems and more specifically to systems and methods for powder pretreatment to influence the microstructure of components manufactured in an additive system using a powder feedstock.

[0002] At least some additive manufacturing systems involve the accumulation of a material processed into a powder to produce a component. This process can produce complex components from expensive materials at reduced cost and with improved manufacturing efficiency. At least some known additive manufacturing systems, such as DMLM systems, produce components using a laser device, a manufacturing platform, and a powder material, such as, without limitation, a metal powder having a fine arrangement of second-phase precipitates, such as carbides, oxides, borides, and topologically close-packed (TCP) phases. The laser device generates a laser beam that melts the powder material on the manufacturing platform in and around the area where the laser beam encounters the powder material, resulting in a melt pool.The melt pool cools rapidly, resulting in a fine array of second-phase precipitates within the fabricated component. This fine array of precipitates can lead to finite grain size, difficulty recrystallizing the alloys, and impaired mechanical performance, such as creep resistance, compared to alloys produced in a cast mold.

[0003] AT 015 102 U1 describes a process for the layer-by-layer production of a hard metal body using 3D printing. A hard metal powder consisting of particles with a sintered tungsten carbide (WC) binder metal structure is applied layer by layer and locally solidified at defined locations using a directed energy beam until the finished hard metal body is formed.

[0004] US 2016 / 0 375 493 A1 discloses additive manufacturing processes for the production of sintered cemented carbide articles based on metal carbide powders (e.g., tungsten carbide and a metallic binder phase). First, a green compact is produced from sintered cemented carbide powder using additive processes. The green compact has a density of less than 50% of the theoretical density. Subsequent sintering produces articles with densities exceeding 90% of the theoretical full density, comparable to cemented carbide articles produced using conventional powder metallurgy.

[0005] WO 2015 / 030 879 A2 describes a method for producing a ceramic turbine component, in which a ceramic powder is mixed with a powder mixture containing a metallic binder. This powder mixture is then formed into a turbine component, which is subsequently densified by partial transient liquid-phase sintering.

[0006] DE 10 2011 120 540 A1 describes a method for producing a sinter powder consisting of ceramic reinforcement particles coated with a melt of a hypereutectic AlSi metal matrix alloy. Melt droplets and ceramic particles are selectively brought together in an impact zone so that the particles are enveloped by the melt upon impact. The sinter powder is formed by the solidification of these coated particles. The resulting sinter powder and a sintered body produced therefrom are also disclosed.

[0007] DE 10 2004 029 759 A1 also discloses a process for producing WC-Co composite powder with a thin cobalt coating. The starting point is a conventionally agglomerated WC-6Co powder. Plasma treatment in a circulating fluidized bed under an argon-hydrogen atmosphere evenly distributes the cobalt within the agglomerates, resulting in temporary cobalt melting and oxide reduction, which improves cobalt wetting of the WC grains.

[0008] EP 2 799 179 A1 describes an additive manufacturing process (laser cladding) for producing a final microstructure with a precisely adjustable grain size and intermetallic phase. For this purpose, various powder layers consisting of mixtures of two powder components (A and B) are successively applied and fused.

[0009] US 5 803 992 A also describes a process for producing a permanent magnet from a melt with a base alloy of rare earths (RE), iron and / or cobalt and boron. In addition, transition metals (TR, e.g. Ti, Zr, Mo) and carbon and / or nitrogen are added in stoichiometric amounts to form stable compounds such as carbides, nitrides or carbonitrides.

[0010] Based on this, the object of the invention is to provide an improved method for processing a powder starting material that eliminates the disadvantages of the prior art. In particular, it should prevent a fine arrangement of second-phase precipitates within the product. SHORT DESCRIPTION

[0011] The object of the invention is achieved with the method for processing a powder starting material according to claim 1. The method according to the invention for processing a powder starting material including a plurality of particles serves to form a product. The product includes a plurality of grains having a nominal grain size. The method comprises atomizing a base material to produce the powder material and heat treating a powder material at a temperature in the range up to 1400°C for a period of up to 100 hours to form the powder starting material (21), wherein the plurality of particles of the powder starting material include a collection of phase precipitates arranged within a matrix material. The collection of phase precipitates has a first nominal size distribution.Heat treating the powder material to form the starting material (21) comprises nucleating the phase within the powder material and growing a phase within the powder material to form the collection of phase particles. The matrix material comprises one of the following: an Al-based alloy, a Co-based alloy, an Fe-based alloy, a Ni-based alloy, and a Ti-based alloy. The collection of phase particles comprises one or more of the following: carbides, borides, nitrides, oxides, intermetallics, and topographically close packed (TCP) phases. The method further comprises forming a solid component from the powder starting material in an additive manufacturing process and producing the article from the solid component.The first nominal size distribution of the phase particle aggregate is sized such that at least a portion of the phase particle aggregate persists throughout the additive manufacturing process and is present as a processed phase particle aggregate in the solid component. Furthermore, the processed phase particle aggregate has a second nominal size distribution effective to produce the nominal grain size of the product.

[0012] Embodiments of the method in accordance with one aspect may further comprise, for example, at least one or more of the following features:

[0013] Embodiments of the method may include heat-treating a powder material to form the powder starting material. In the method, heat-treating the powder material to form the powder starting material may include growing a phase within the powder material to form the collection of phase particles. The method may include nucleating the phase within the powder material.

[0014] Embodiments of the method may include atomizing a base material to produce the powder material. Atomizing the base material may include processing the base material using inert gas atomization, water atomization, oil atomization, vacuum atomization, plasma atomization, or centrifugal atomization.

[0015] In embodiments of the method, the matrix material may comprise one or more of the following materials: aluminum (Al), cobalt (Co), iron (Fe), nickel (Ni), and titanium (Ti).

[0016] In embodiments of the method, the matrix material may comprise one of the following: an aluminum-based alloy, an Fe-based alloy, a Ni-based alloy, and a Ti-based alloy.

[0017] In embodiments of the method, the collection of phase particles may comprise one or more of the following: carbides, borides, nitrides, oxides, intermetallics, and topographically close packed (TCP) phases.

[0018] In embodiments of the method, producing the fabricated component from the solid component may comprise heat treating the solid component.

[0019] In another aspect, a method is provided for forming a solid component including a plurality of grains having a nominal grain size. The method includes atomizing a metal alloy to produce a powder material including a matrix material and a collection of phase particles disposed within the matrix material. The first collection of phase particles has a first nominal size distribution. The method also includes increasing the first nominal size distribution of the population of phase particles to a second nominal size distribution disposed within the matrix material. Additionally, the method includes directing an energy beam output from an energy device onto a layer of powder material, and creating a molten pool in the powder material layer with the energy beam to produce a solid component.The energy beam applies energy to the powder material that is insufficient to completely melt the cluster of phase particles. Additionally, the second nominal size distribution of the cluster of phase particles is effective in generating the nominal grain size of the solid component.

[0020] Embodiments of the method in accordance with the other aspects may additionally comprise, for example, one or more of the following features:

[0021] In embodiments of the method, increasing the first nominal size distribution of the collection of phase particles may comprise heat-treating the powder material. Heat-treating the powder material may comprise heat-treating the powder material to a temperature in a range between and including about 800°C and about 1200°C.

[0022] In embodiments of the method, increasing the first nominal size distribution may comprise establishing a second nominal size distribution that is at least 10% larger than the first nominal size distribution.

[0023] In embodiments of the method, atomizing the metal alloy may comprise processing the metal alloy using inert gas atomization, water atomization, oil atomization, vacuum atomization, plasma atomization, or centrifugal atomization.

[0024] In embodiments of the method, sputtering the metal alloy may comprise sputtering one of the following: Al-based alloy, Co-based alloy, Fe-based alloy, Ni-based alloy, and Ti-based alloy.

[0025] In embodiments of the method, the matrix material may comprise one or more of the following materials: aluminum (Al), cobalt (Co), iron (Fe), nickel (Ni), and titanium (Ti).

[0026] In embodiments of the method, the collection of phase particles may comprise one or more of the following: carbides, borides, nitrides, oxides, intermetallics, and topographically close packed (TCP) phases.

[0027] Embodiments of the method may include manufacturing a fabricated component from a solid component. Manufacturing the fabricated component from the solid component may include heat treating the solid component. DRAWINGS

[0028] These and other features, aspects, and advantages of the present disclosure will be better understood when the following detailed description is read with reference to the accompanying drawings, in which like reference numerals represent like parts throughout the drawings, wherein: Fig. 1 is a schematic view of an exemplary additive manufacturing system including a pretreatment heating system; Fig. 2 a schematic view of an exemplary additive manufacturing facility including the additive manufacturing system shown in Fig. 1, is; and Fig. 3 two micrographs of the microstructure of particles of a powder starting material for use in the additive manufacturing system shown in Fig. 1, is.

[0029] Unless otherwise indicated, the drawings provided herein are intended to illustrate the features of embodiments of this disclosure. These features are believed to be applicable in a wide variety of systems incorporating one or more embodiments of this disclosure. As such, the drawings are not intended to include all conventional features known to those skilled in the art to be necessary for practicing the embodiments disclosed herein. DETAILED DESCRIPTION

[0030] In the following description and claims, reference is made to a number of terms which shall be defined to have the following meaning.

[0031] The singular forms “einer”, “eine” and “der, die, das” include plural references unless the context clearly indicates otherwise.

[0032] "Optional" or "Optional" means that the event or circumstance described below may or may not occur and that the description includes examples where the event occurs and examples where it does not.

[0033] Approximate language, as used throughout the description and claims, may be applied to modify any quantitative statement that can permissibly vary without altering the basic function to which it relates. Accordingly, values modified by a term or terms such as "about," "approximately," and "substantially" are not intended to be specified to the precise value stated. In at least some examples, the approximate language may correspond to the precision of an instrument for measuring the value. Here and throughout the description and claims, range limitations may be combined and / or interchanged; such ranges are identified and include all subranges encompassed therein, unless the context or language indicates otherwise.

[0034] As used herein, the terms "processor" and "computer" and related terms, e.g., "processing device" and "computing device," are not limited to those integrated circuits referred to in the art as computers, but refer generally to a microcontroller, a microcomputer, a programmable logic controller (PLC), an application-specific integrated circuit, and other programmable circuits, and these terms are used interchangeably herein. In the embodiments described herein, memory may include, but is not limited to, a computer-readable medium such as random access memory (RAM) and a computer-readable non-transitory medium such as flash memory.Alternatively, a floppy disk, a compact disc read-only memory (CD-ROM), a magneto-optical disk (MOD), and / or a digital versatile disc (DVD) may also be used. Also, in the embodiments described herein, additional input channels may include, but are not limited to, computer peripherals connected to a user interface, such as a mouse and keyboard. Alternatively, other computer peripherals may be used, including, but not limited to, a scanner. Furthermore, additional output channels in the exemplary embodiments may include, but are not limited to, a user interface monitor.

[0035] As used herein, the term "non-transitory computer-readable media" is intended to be representative of any tangible computer-based device used in any method or technology for short-term and long-term storage of information, such as computer-readable instructions, data structures, program modules and submodules, and other data in any device. Therefore, the methods described herein are encoded as executable instructions embodied in a tangible, non-transitory computer-readable medium, including, without limitation, a storage device and / or a memory device. Such instructions, when executed by a processor, cause the processor to perform at least a portion of the methods described herein.

[0036] In addition, the term “non-transitory computer-readable media” as used herein includes all tangible computer-readable media, including, without limitation, non-transitory computer storage devices, including, without limitation, volatile and non-transitory media, removable and non-removable media, and firmware, physical and virtual memory, CD-ROMs, DVDs, and any other digital source such as a network or the Internet, and digital means yet to be developed, with the sole exception of a transient propagating signal.

[0037] Embodiments of a powder material pretreatment heating system, for example, for use in an additive manufacturing system, preheat a powder feedstock prior to manufacturing a component from the heat-treated powder feedstock. The pretreatment heating system applies heat to a powder feedstock before the powder feedstock is formed into a component to facilitate converting the powder feedstock to a state where one or more phases exist as a dispersion within the microstructure of the powder particles of the powder feedstock. Heat treatment of the powder feedstock in the pretreatment heating system activates a predetermined degree of second-phase particle coarsening and / or generation. Coarsening includes combining at least some of the second-phase particles with other second-phase particles to increase the second-phase particle size.The second-phase particles have a composition and size such that, when processed, for example, in an additive manufacturing system to produce a consolidated article, the second-phase particles persist throughout the consolidation process and are present within the consolidated article. The second-phase particles may be altered during the additive manufacturing process (for example, they may partially melt or dissolve, so that the particles in the consolidated article are, on average, smaller than in the powder starting material), but the particles are present within the consolidated article and have a second-phase particle size that is largely responsible for the grain size of the material (via Zener anchoring) after post-heat treatment.Smaller size distributions of, for example, oxides and carbides often result in finer grain sizes in the solid component after heat treatment. By coarsening and / or generating such second-phase particles within the powder feedstock prior to powder consolidation, the final microstructure of the solid component can be controlled in a manner that results in increased grain sizes, improved alloy recrystallization, and comparable creep behavior compared to alloys processed in a cast mold, which is typically unattainable with typical additive manufacturing systems.

[0038] Fig. 1 is a schematic view of an exemplary additive manufacturing system 10. In the exemplary embodiment, the additive manufacturing system 10 is a direct metal laser melting (DMLM) system. Although embodiments are described herein with reference to a DMLM system, it is noted that the additive manufacturing system 10 may be any powder consolidation process that enables the additive manufacturing system 10 to manufacture a component using at least one powder material. For example, and without limitation, the additive manufacturing system 10 may be a direct metal laser sintering (DMLS) system, a selective laser sintering (SLS) system, a selective laser melting (SLM) system, an electron beam melting (EBM) system, a binder jet system, or any other additive manufacturing system that requires a metal powder feedstock.

[0039] To produce the powder material, powder particles are first prepared from a starting material. Several powder production techniques are known. In inert gas atomization, for example, the starting material to be powdered is melted, and a jet of inert gas is directed against a jet of molten metal. Droplets of the molten metal are produced, and these droplets solidify to produce the powder particles. Other atomization methods include water atomization, oil atomization, vacuum atomization, plasma atomization, and centrifugal atomization, including processes such as rotating electrode, rotating cup, and rotating disc methods. However produced, powder particles are then processed to form the component.

[0040] In the exemplary embodiment, the additive manufacturing system 10 includes a manufacturing platform 12, a pre-treatment heating system 13, an energy device 14 configured to generate an energy beam 16, a first scanning device 18 configured to selectively direct the energy beam 16 across the manufacturing platform 12, an energy beam 16, and a post-treatment heating system 15. The exemplary additive manufacturing system 10 further includes a computing device 24 and a controller 26 configured to control one or more components of the additive manufacturing system 10, as described in greater detail herein.

[0041] A powder feedstock 21 includes a matrix material including a plurality of particles and a collection of phase particles disposed within the particles of the matrix material. The particles include materials suitable for forming a consolidated or solid component 28, including, without limitation, atomized alloys of cobalt (Co), iron (Fe), aluminum (Al), titanium (Ti), nickel (Ni), and combinations thereof. In other embodiments, the powder feedstock 21 includes any suitable type of powder feedstock that enables the additive manufacturing system 10 to function as described herein, including, for example, and without limitation, ceramic powders, metal-coated ceramic powders, and thermosetting or thermoplastic resins.In one embodiment, the collection of phase particles of powder starting material 21 includes a plurality of small second-phase particles embedded within the particles of the matrix material. In the exemplary embodiment, the plurality of small second-phase particles includes any carbides, borides, nitrides, oxides, intermetallics, or topographically close-packed (TCP) phases that enable the additive manufacturing system 10 to function as described herein. In other embodiments, the small second-phase particles may be nucleated and / or formed during a heat treatment process.

[0042] In the exemplary embodiment, the pretreatment heating system 13 includes a furnace 20 configured to heat the powder starting material 21 and, in some embodiments, mix the powder starting material 21 during the heat treatment process. Mixing the powder starting material 21 during the heat treatment process facilitates preventing sintering of the powder starting material 21 and / or partial combining. In exemplary embodiments, the furnace 20 includes, for example, and without limitation, a rotary kiln, a tube kiln, a fluidized bed kiln, a cyclone kiln, and / or an ultrasonic kiln. However, the furnace 20 includes any heating device that enables the additive manufacturing system 10 to function as described herein.In another embodiment, the starting material 21 may be at least partially sintered by the furnace 20 and subsequently crushed or reduced back into a powder material. For example, and without limitation, the sintered starting material 21 may be subjected to post-heat treatment separation using one or more of milling, breakboxing, molding, and / or other separation processes.

[0043] In the exemplary embodiment, the powder feedstock 21 is placed in a pretreatment heating system 13 and heated to a predetermined temperature for a predetermined time by the furnace 20. In one embodiment, the pretreatment heating system 13 heats, for example, a Co, Fe, Ni, and Ti-based alloy powder feedstock to a temperature in the range between and including 700 degrees Celsius (°C) (1292 degrees Fahrenheit (°F)) to 1400°C (2552°F). Additionally, the pretreatment heating system 13 maintains such a powder feedstock within this temperature range for a duration of up to 100 hours.More specifically, the pretreatment heating system 13 can be used to heat nickel- and Co-based alloys to a temperature in the range between and including 800°C (1472°F) to 1200°C (2192°F) for a period of up to 72 hours to facilitate the formation and / or growth of, for example, a plurality of small second-phase particles including carbides, oxides, and TCP phases. Iron-containing alloys or iron-based alloys can be heated to a temperature in the range between and including 700°C (1292°F) to 1350°C (2462°F) for a period of up to 100 hours to facilitate the formation and / or growth of, for example, a plurality of small second-phase particles including carbides, oxides, and TCP phases.In addition, Ti-based alloys can be heated to a temperature in the range between and including 900°C (1652°F) to 1400°C (2552°F) for a period of up to 100 hours to enable the formation and / or growth of, for example, a variety of small second-phase particles including carbides and borides.

[0044] In another embodiment, the pretreatment heating system 13 heats an Al-based alloy powder feedstock to a temperature in the range between and including 100°C (212°F) and 550°C (1022°F) for a period of up to 1000 hours to enable the formation and / or growth of, for example, a plurality of small second-phase particles including oxides and borides. Additionally, in another embodiment, the pretreatment heating system 13 heats a refractory powder feedstock, such as a ceramic powder material, to a temperature greater than 2000°C (3632°F) for a period of up to 1000 hours.

[0045] The heat treatment of the powder starting material 21 in the pretreatment heating system 13 causes the plurality of small second-phase particles to coarsen into a plurality of large second-phase particles and / or produces a plurality of second-phase particles having a selected first nominal size distribution and substantially uniformly distributed throughout the powder starting material 21. As described herein, the plurality of large second-phase particles improves the physical properties of the solid component 28.

[0046] In another embodiment, the pretreatment heating system 13 is configured to heat-treat the powder starting material 21 in a selected atmosphere configured to facilitate coarsening and / or the generation of the plurality of second-phase particles. For example, the powder starting material 21 may be heat-treated in an atmosphere including, for example, and without limitation, an inert, reducing, or oxidizing atmosphere to facilitate manipulation of the volume fraction of the second-phase particles on the surface and within the metal powder particles. In one embodiment, the powder starting material 21 may be heat-treated in an inert environment, such as a vacuum or argon-filled environment.In another embodiment, the powder starting material 21 may be heat treated in a reactive environment, such as a carbonizing atmosphere (e.g., a gas including methane, carbon monoxide, and / or carbon dioxide).

[0047] In some embodiments, the pretreatment heating system 13 is configured to selectively select heat treatment temperatures and durations to coarsen one or more second-phase precipitates more than others, enabling fine-tuning of the final microstructure of the component 28. That is, the pretreatment heating system 13 selectively selects heat treatment temperatures and durations to enable coarsening of carbides while maintaining the particle size of oxides. In another embodiment, the pretreatment heating system 13 is configured to heat powder feedstock 21 to precipitate topologically close-packed (TCP) phases, which may be more stable at higher temperatures than conventional strengthening phases such as gamma prime and gamma two-prime.In other embodiments, the pretreatment heating system 13 is configured to heat powder feedstock 21 as a purification procedure to develop adsorbed species shortly before consolidation to enable improvement of the manufacturability and / or physical properties of the component 28, such as, without limitation, strength, toughness, ductility, hardness, corrosion resistance, high / low temperature performance, and / or wear resistance.

[0048] In the exemplary embodiment, the powder starting material 21 is transferred from the pretreatment heating system 13 to the exemplary manufacturing platform 12 by means of a material transfer system 23. The transfer system 23 includes a container 25 configured to transfer the powder starting material 21. In one embodiment, the powder starting material 21 is transferred within the container 25 in an inert environment. In the exemplary embodiment, the powder starting material 21 is transferred to the container 25 from the pretreatment heating system 13 as indicated by arrow 9 and then from the container 25 to the manufacturing platform 12 as indicated by arrow 11.In another embodiment, the transfer system 23 includes a series of conduits, tubes, or belts (not shown) configured to automatically transfer powder feedstock 21 from the pretreatment heating system 13 to the manufacturing platform 12. In the exemplary embodiment, powder feedstock 21 is at least partially melted and resolidified during the additive manufacturing process to form a solid component 28, for example, on the manufacturing platform 12. In the exemplary embodiment, the manufacturing platform 12 remains stationary during the formation process.However, in another embodiment, the manufacturing platform 12 is configured to mix the powder starting material 21 to prevent sintering of the powder starting material 21, for example, when heat-treated powder starting material 21 is transferred to the manufacturing platform 12 at an elevated temperature.

[0049] As in Fig. 1, the energy device 14 is configured to generate the energy beam 16 of sufficient energy to at least partially melt the powder starting material 21. However, the energy beam 16 applies insufficient energy to the powder starting material 21 to completely melt the plurality of large second-phase particles. As such, at least a portion of the plurality of large second-phase particles exists during the manufacture of the solid component 28 and is present as a processed collection of phase particles in the solid component 28. The processed collection of phase particles has a second nominal size distribution effective to produce a selected (or nominal) grain size of the solid component 28.Therefore, the second nominal size distribution of the large second-phase particles present in the solid component 28 enables an altered microstructure that allows, for example, large grain sizes and improved recrystallization of the alloy after post-heat treatment and comparable creep behavior compared to alloys produced in a cast mold.

[0050] In the exemplary embodiment, the energy device 14 is a laser device, such as a neodymium-doped yttrium aluminum garnet (Nd:YAG) solid-state laser, that emits the energy beam 16. In alternative embodiments, the additive manufacturing system 10 includes an energy device 14 that enables the additive manufacturing system 10 to function as described herein, such as a continuous wave, a modulated wave, a pulsed wave laser, a carbon dioxide laser, or an electron beam generator. Furthermore, although the additive manufacturing system 10 is shown and described as including a single energy device 14, in some embodiments, the additive manufacturing system 10 includes more than one laser device.For example, in one embodiment, the additive manufacturing system 10 includes a first laser device having a first power and a second laser device having a second power different from the first laser power, or at least two laser devices having substantially the same power output. In yet another embodiment, the additive manufacturing system 10 includes any combination of laser devices that enable the additive manufacturing system 10 to function as described herein.

[0051] In the exemplary embodiment, the energy device 14 is optically coupled to optical elements 30 and 32, which enable the focusing of the energy beam 16 onto the manufacturing platform 12. The optical elements 30 and 32 include a beam collimator 30 disposed between the energy device 14 and a scanning device 18, and in some embodiments, an F-theta lens 32 disposed between the scanning device 18 and the manufacturing platform 12. In other embodiments, the additive manufacturing system 10 includes any suitable type and arrangement of optical elements that provide a collimated and / or focused energy beam onto the manufacturing platform 12.

[0052] The first scanning device 18 is configured to direct the energy beam 16 across selected portions of the manufacturing platform 12 to create the solid component 28. In the exemplary embodiment, the scanning device 18 is a galvanometer scanning device including a mirror 34 coupled to a galvanometer-controlled motor 36 (generally an actuator). The motor 36 is configured to move (specifically, rotate) the mirror 34 in response to signals received from the controller 26, thereby deflecting the energy beam 16 across selected portions of the manufacturing platform 12. In some embodiments, the mirror 34 includes a reflective coating having a reflectance spectrum corresponding to the wavelength of the energy beam 16.

[0053] Although the scanning device 18 is illustrated with a single mirror 34 and a single motor 36, the scanning device 18 includes any suitable number of mirrors and motors that enable the scanning device 18 to function as described herein. For example, in one embodiment, the scanning device 18 includes two mirrors and two galvanometer-controlled motors, each coupled to one of the mirrors. In yet another embodiment, the scanning device 18 includes any suitable scanning device that enables the additive manufacturing system 10 to function as described herein, such as two-dimensional (2D) scanning galvanometers, three-dimensional (3D) scanning galvanometers, and dynamic focusing galvanometers.

[0054] The computing device 24 includes a computer system having at least one processor (not shown) in Fig. 1 that executes executable instructions to operate the additive manufacturing system 10. The computing device 24 includes, for example, a calibration model of the additive manufacturing system 10 and an electronic computer manufacturing file associated with a component, such as component 28. The calibration model includes, for example and without limitation, an expected or desired melt pool size and temperature under a given set of operating conditions (e.g., a power output of the energy device 14) of the additive manufacturing system 10. The manufacturing file includes manufacturing parameters used to control one or more components of the additive manufacturing system 10. Manufacturing parameters include, without limitation, a power output of the energy device 14, a scanning speed of the scanning device 18, and a position and orientation of the scanning device 18 (specifically, mirror 34).In the exemplary embodiment, the computing device 24 and the controller 26 are shown as separate devices. In other embodiments, the computing device 24 and the controller 26 are combined into a single device that functions as both the computing device 24 and the controller 26, each as described herein.

[0055] The controller 26 includes any suitable type of controller that enables the additive manufacturing system 10 to function as described herein. In one embodiment, the controller 26 is a computer system including at least one processor and at least one memory device that execute executable instructions to control the operation of the additive manufacturing system based at least in part on instructions from human operators. For example, the controller 26 includes a 3D model of the component 28 to be manufactured by the additive manufacturing system 10. Executable instructions executed by the controller 26 include controlling the power output of the energy device 14 and controlling a position and scanning speed of the scanning device 18.

[0056] The controller 26 is configured to control one or more components of the additive manufacturing system 10 based on the manufacturing parameters associated with a stored manufacturing file, for example, within the computing device 24. In the exemplary embodiment, the controller 26 is configured to control the scanning device 18 based on a manufacturing file associated with a component to be manufactured with the additive manufacturing system 10. More specifically, the controller 26 is configured to control the position, movement, and scanning speed of the mirror 24 using the motor 36 based on a predetermined path defined by a manufacturing file associated with the component 28. The controller 26 is also configured to control other components of the additive manufacturing system 10, including, without limitation, the energy device 14.For example, in one embodiment, the controller 26 controls the energy output of the energy device 14 based on manufacturing parameters associated with a manufacturing file.

[0057] In the exemplary embodiment, the additive manufacturing system 10 also includes a post-treatment heating system 15. The solid component 28 is transferred from the manufacturing platform 12 to the post-treatment heating system 15 by the transfer system 13 as indicated by arrow 17. In the exemplary embodiment, the post-treatment heating system 15 includes a furnace 22 configured to heat and / or stress relieve the solid component 28 to produce a fabricated component. Stress relieve includes slowly cooling the solid component to reduce internal stresses. During the stress relieve process, the component 28 is placed in the post-treatment heating system 15 at a predetermined temperature. The temperature of the post-treatment heating system 15 is slowly reduced, allowing the fabricated component to cool slowly.Stress relieving improves the properties of the fabricated component made from the solid component 28. In certain embodiments, rapid cooling from stress relieving temperatures may be preferred.

[0058] Fig. 2 is a schematic view of an exemplary additive manufacturing facility 200. In the exemplary embodiment, the additive manufacturing facility 200 includes a centralized pretreatment heating system 202, a plurality of additive manufacturing systems 210, and a centralized posttreatment heating system 204. The centralized pretreatment heating system 202 includes a furnace 216 configured to heat multiple batches of powder feedstock 21 and mix the powder feedstock 21 during the heating process. Mixing the powder feedstock 21 during the heating process prevents the powder feedstock 21 from sintering. Heating and mixing multiple batches of powder feedstock 21 at the same time improves the efficiency of the additive manufacturing facility 200 and reduces the manufacturing cost of the solid component 28.In the exemplary embodiment, the furnace 216 includes, for example, without limitation, a rotating furnace, a tube furnace, a fluidized bed furnace, a cyclone furnace, and / or an ultrasonic applicator. However, in alternative embodiments, the furnace 216 includes any heating device that enables the additive manufacturing system 10 to function as described herein.

[0059] In the exemplary embodiment, a powder feedstock 21 is placed in the centralized pretreatment heating system 202 and heated to a predetermined temperature for a predetermined period of time. The centralized pretreatment heating system 202 heats, for example, a Co-, Fe-, Ni-, and Ti-based alloy powder feedstock to a temperature in the range between and including 700 degrees Celsius (°C) (1292 degrees Fahrenheit (°F)) and 1400°C (2552°F). Additionally, the centralized pretreatment heating system 202 maintains such a powder feedstock within this temperature range for a period of up to 100 hours.More specifically, the centralized pretreatment heating system 202 can be used to heat Ni- and Co-based alloys to a temperature in the range between and including 800°C (1472°F) to 1200°C (2192°F) for a period of up to 72 hours to enable the formation and / or growth of, for example, a plurality of small second-phase particles including carbides, oxides, and TCP phases. Iron-containing alloys or iron-based alloys can be heated to a temperature in the range between and including 700°C (1292°F) to 1350°C (2462°F) for a period of up to 100 hours to enable the formation and / or growth of, for example, a plurality of small second-phase particles including carbides, oxides, and TCP phases.In addition, Ti-based alloys can be heated to a temperature in the range between and including 900°C (1652°F) to 1400°C (2552°F) for a period of up to 100 hours to enable the formation and / or growth of, for example, a plurality of small second-phase particles including carbides and borides.

[0060] In another embodiment, the centralized pretreatment heating system 202 heats an aluminum-based alloy powder feedstock to a temperature in the range between and including 100°C (212°F) and 550°C (1022°F) for a period of up to 1000 hours to enable the formation and / or growth of, for example, a plurality of small second-phase particles including oxides and borides. Additionally, in another embodiment, the centralized pretreatment heating system 202 heats a refractory powder feedstock, for example, a powder ceramic material, to a temperature >2000°C (3632°F) for a period of up to 1000 hours.

[0061] Heating the powder feedstock 21 in the centralized pretreatment heating system 202 causes the plurality of small second-phase particles to coarsen and / or combine into a plurality of large second-phase particles and / or produces a plurality of large second-phase particles having a selected first nominal size distribution and substantially uniformly distributed throughout the powder feedstock 21. As described herein, the plurality of large second-phase particles improves the physical characteristics of solid components 28.

[0062] The powder starting material 21 is transferred from the centralized pretreatment heating system 202 to at least one of the additive manufacturing systems 210 through the transfer system 206. In the exemplary embodiment, the transfer system 206 includes a container 208 configured to transfer the powder starting material 21. In some embodiments, the powder starting material 21 is transferred through the container 208 in an inert environment. In the exemplary embodiment, the powder starting material 21 is transferred to the container 208, which is transferred to the additive manufacturing system 210, as indicated by arrows 212.

[0063] After powder starting material 21 is processed in the additive manufacturing system 210 to produce the solid component 28, the solid component 28 is transferred from the additive manufacturing system 210 to the centralized post-treatment heating system 204 by the transfer system 206 as indicated by arrow 214. In the exemplary embodiment, the centralized post-treatment heating system 204 includes a furnace 218 configured to heat and / or destress the solid component 28 to produce a fabricated component. Destressing includes slowly cooling the solid component 28 to reduce internal stresses. During the destressing process, the solid component 28 is placed in the centralized post-treatment heating system 204 at a predetermined temperature.The temperature of the centralized post-treatment heating system 204 is slowly reduced, allowing the solid component 28 to cool slowly. The stress-relieving process improves the properties of the manufactured component made from the solid component 28. Stress-relieving multiple solid components 28 at the same time improves the efficiency of the additive manufacturing facility 200 and reduces the manufacturing cost of the manufactured component.

[0064] Fig. Figure 3 shows two micrographs of the microstructure of particles 300 and 302 of powder starting material 21. View 1 shows an approximately 10,000x magnification of particle 300 of powder starting material 21 before pretreatment heating system 13 has heat-treated powder starting material 21. View 2 shows an approximately 10,000x magnification of particle 302 of powder starting material 21 after pretreatment heating system 13 has heat-treated powder starting material 21. In the illustrated embodiment, the microstructure of particle 300 includes a plurality of small second-phase particles 304, represented by the small particle shown in View 1, distributed throughout the microstructure of particle 300.In View 2, the microstructure of particle 302 of powder starting material 21 includes a plurality of second-phase particles 306, represented by the smaller particles drawn in View 2, distributed within the microstructure of particle 302. In the illustrated embodiment, second-phase particles 304 and 306 are carbide particles. However, in alternative embodiments, second-phase particles 304 and 306 include any carbide, oxide, nitrite, intermetallic compound, or TCP phase particles that allow additive manufacturing system 10 to operate as described herein.

[0065] As in Fig.3, the second-phase particles 304 in view 1 are smaller than the second-phase particles 306 in view 2. In the exemplary embodiment, the powder starting material 21 is placed in the pretreatment heating system 13 and heated to a predetermined temperature for a predetermined period of time. Heating the powder starting material 21 in the pretreatment heating system 13 enables the second-phase particles 304 to be created and / or coarsened into larger second-phase particles 306. Additionally, in some embodiments, heating the powder starting material 21 in the pretreatment heating system 13 enables the second-phase particles 304 to be nucleated within the powder starting material.For example, in one exemplary embodiment, the powder starting material 21 is placed in the pretreatment heating system 13 and heated to produce an average second-phase particle 306 size (or nominal size distribution) that is at least 10% larger than the second-phase particles 304. The second-phase particles 306 are well-shaped and larger (e.g., at least 10% larger) than the second-phase particles 304. Coarser and larger second-phase particles 306 are included to improve the physical properties of the solid component 28, such as strength, toughness, ductility, hardness, corrosion resistance, high / low temperature performance, and / or wear resistance.

[0066] Embodiments of the additive manufacturing system with a pretreatment heating system, as described herein, heat a powder feedstock before a component is manufactured from the powder feedstock. The additive manufacturing system includes a pretreatment heating system, a manufacturing platform, and an energy device. The pretreatment heating system applies heat to a powder feedstock before the powder feedstock is transferred to the manufacturing platform. The energy device generates an energy beam that is directed at the powder feedstock of the manufacturing platform. The energy beam melts the powder material on the manufacturing platform in and around the area where the energy beam impacts the powder material, resulting in a molten puddle. The molten puddle cools to form a layer of the component.Preheating the powder feedstock in the pretreatment heating system coarsens the small second-phase particles into large second-phase particles, for example, particles at least 10% larger. In the preferred embodiment, the energy beam applies energy to the powder feedstock that is insufficient to completely melt the large second-phase particles, resulting in a plurality of large second-phase particles with a second nominal size distribution that are substantially uniformly distributed throughout the powder feedstock, resulting in a microstructure that exhibits large grain sizes, improved alloy recrystallization, and comparable creep behavior compared to alloys produced in a cast mold.

[0067] An exemplary technical effect of the method and system as described herein includes (a) preheating a powder feedstock; (b) generating large second-phase particles within the powder feedstock; (c) retaining at least a portion of the large second-phase particles throughout the additive manufacturing process; (d) postheating a component; (e) increasing grain sizes within a component; (f) enhancing recrystallization of an alloy within a component; and (g) improving creep behavior within a component.

[0068] Such embodiments include the use of one or more electronic or computing devices. Such devices typically include a processor, processing device, or controller, such as a general-purpose central processing unit (CPU), a graphics processing unit (GPU), a microcontroller, a reduced instruction set computer (RISC) processor, an application-specific integrated circuit (ASIC), a programmable logic circuit (PLC), a field-programmable gate array (FPGA), a digital signal processing (DSP) device, and / or any other circuit or processing device capable of performing the functions described herein. The methods described herein may be encoded as executable instructions embodied in a computer-readable medium, including, without limitation, a storage device and / or a memory device.Such instructions, when executed by a processing device, cause the processing device to perform at least part of the method described herein. The above examples are exemplary only and are therefore not intended to limit the definition and / or meaning of the terms processor and processing device.

[0069] Example embodiments of the additive manufacturing system include a pretreatment heating system, which is described in detail above. The devices, systems, and methods are not limited to the specific embodiments described herein; rather, the operations of the method and components of the system may be used independently and separately from other operations or components described herein. For example, the systems, methods, and devices described herein may have other industrial or consumer applications and are not limited to interoperability with additive manufacturing systems as described herein. Rather, one or more embodiments may be implemented and used in connection with other industries.

[0070] Although certain features of various embodiments of the disclosure may be shown in some drawings and not in others, this is for convenience only. Consistent with the principles of the disclosure, any feature of one drawing may be referenced or claimed in combination with any feature of any other drawing.

[0071] This written description uses examples to disclose the embodiments, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims and may include other examples that occur to those skilled in the art. Such other examples are intended to be included within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

[0072] A method of processing a powder starting material to form a manufactured component is provided. The manufactured component includes a plurality of grains having a nominal grain size. The method includes providing the powder starting material having a collection of phase particles with a first nominal size distribution distributed in a matrix material. The method includes forming a solid component from the powder starting material in an additive manufacturing process and manufacturing the article of manufacture from the solid component. The first nominal size distribution of the collection of phase particles is sized such that at least a portion of the collection of phase particles persists throughout the additive manufacturing process and is present as a processed collection of phase particles in the solid component.In addition, the processed collection of phase particles has a second nominal size distribution which is effective to produce the nominal grain size of the product. LIST OF REFERENCE SYMBOLS 9 Arrow 10 Additive Manufacturing System 11 Arrow 12 Manufacturing platform 13 Pretreatment heating system 14 Energy device 15 Aftertreatment heating system 16 Energy beam 17 Arrow 18 scanner 20 oven 21 Source material 22 Oven 23 Transfer system 24 Calculation device 25 containers 26 Control 28 Fixed component 30, 32 Optical element 34 mirrors 36 engine 200 additive manufacturing facilities 202 Pretreatment heating system 204 Aftertreatment heating system 206 Transfer system 208 containers 210 additive manufacturing system 212, 214 arrows 218 Oven 300, 302 particles 304, 306 Second-phase particles

Claims

[1] A method of processing a powder starting material (21) including a plurality of particles to form a product, the product having a plurality of grains with a nominal grain size, the method comprising: Atomizing a base material to produce the powder material; Heat treating a powder material at a temperature in the range up to 1400°C for a period of up to 100 hours to form the powder starting material (21), wherein the plurality of particles of the powder starting material (21) includes a collection of phase particles arranged in a matrix material, the collection of phase particles having a first nominal size distribution, wherein heat treating the powder material to form the powder starting material (21) comprises nucleating the phase within the powder material and growing a phase within the powder material to form the collection of phase particles; wherein the matrix material comprises one of the following: an Al-based alloy, a Co-based alloy, an Fe-based alloy, a Ni-based alloy and a Ti-based alloy, wherein the collection of phase particles comprises one or more of the following: carbides, borides, nitrides, oxides, intermetallics and topographically close packed (TCP) phases, Forming a solid component (28) from the powder starting material (21) in an additive manufacturing process; and Producing the article of manufacture from the solid component (28), wherein the first nominal size distribution of the collection of phase particles is such that at least a portion of the collection of phase particles persists throughout the additive manufacturing process and is present as a processed collection of phase particles in the solid component (28), and wherein the processed collection of phase particles has a second nominal size distribution effective to produce the nominal grain size of the article of manufacture. [2] The method of claim 1, wherein atomizing the base material comprises processing the base material using inert gas atomization, water atomization, oil atomization, vacuum atomization, plasma atomization, or centrifugal atomization. [3] A method according to any one of the preceding claims, wherein the powder starting material (21) is mixed during the heat treatment process to prevent sintering of the powder starting material (21). [4] A method according to any one of the preceding claims, comprising the steps of: Directing an energy beam (16) output by an energy device (14) onto a layer of the powder starting material (21); and Creating a melt pool in the powder material layer with the energy beam (16) to produce a solid component (28), wherein the energy beam (16) applies energy to the powder starting material (21) that is insufficient to completely melt the collection of phase particles, and wherein the second nominal size distribution of the collection of phase particles is effective to produce the nominal grain size of the solid component (28).

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