Manufacture of high entropy carbide (HEC) feedstock

Abstract

Methods for preparing high entropy carbides (HECs), and powders thereof, are provided. One method includes spray-drying a base carbide feedstock and consolidating. Another method includes cold crucible induction of a base carbide feedstock. The HECs produced are of a quality suitable for use in industry. The methods are scalable in size, and suitable for use on an industrial scale. Also included are HEC feedstocks produced by the methods, and articles, such as coatings, produced from the HECs.

Description

[0001]P73350 Manufacture of High Entropy Carbide (HEC) Feedstock Cross-Reference to Related Applications This Application is an International Application claiming the benefit of priority of U.S. Provisional Application No.63 / 654,450, filed May 31, 2024, the disclosure of which is expressly incorporated by reference herein in its entirety. Field of the Invention The subject matter relates to high entropy carbides and methods of manufacturing them, especially on an industrial scale. The manufacturing processes include, but are not limited to, spray drying, sintering, cold crucible, milling, and plasma spheroidization, or a combination of such manufacturing techniques. Background of the Invention High Entropy Alloys and Ceramics (i.e., High Entropy Materials) are a class of materials with performance that frequently deviate from Rule of Mixtures (T.J. Harrington, et al., Acta Materialia, 166:271-280 (March 2019); J. Gild et al., Ceramics Int., vol.26, No.5, 6906-6913 (April 2020)). High entropy carbides (HECs) are generally single-phase solid solutions comprising at least 5 metallic cation species, each present in at least 5 atom% with respect to the metallic cations. The high entropy state is obtained when the cations are homogeneously and randomly distributed within the carbon lattice. HECs tend to exhibit a high degree of stability across a wide temperature range. The high entropy state is theorized to result in thermodynamic stability, especially at high temperatures. Kinetics-based properties, such as diffusion, have been demonstrated to be slower for the disordered lattice of high entropy materials, which is also suggested by the thermodynamic equation ΔG=ΔH˗TΔS. The relative difficulty for cations to diffuse within the high entropy carbide lattice leads to kinetic stability, especially at low temperatures. HECs generally have single-phase face-centered cubic (FCC) structures of two interspersed sublattices (i.e., rocksalt B1 structure). The carbon atoms form an anionic sublattice while the cations collectively form a cationic sublattice. The high entropy state is obtained when the five or more cations in the cationic sublattice are sufficiently randomly{P7335006585093.DOCX}-1-(v1.1) P73350 distributed. Due to the various radii among the combination of cations, the lattice is distorted, which is believed to contribute to the strength and hardness of HEC materials. Like binary carbides, HECs exhibit high melting points, high strength, and high chemical stability. However, the high entropy state of HECs is theorized to result in high temperature stability that exceeds that of binary carbides. HECs are currently made by researchers in batches on a laboratory scale. Current methods for synthesizing HEC feedstock typically only produce a few grams of feedstock and utilize high energy ball milling, planetary ball milling, or carbothermal reduction not suited for industrial use to manufacture powder feedstock to produce a high entropy material product. Furthermore, the feedstocks produced are not suitable for use in many industrial techniques such as thermal spray methods including but not limited to, high velocity oxygen fuel (HVOF), atmospheric plasma spray (APS), and vacuum plasma spray. The feedstocks are not suitable for HVOF, APS, and other spray techniques owing to the low-flowability induced primarily by the morphology (e.g., non-spherical agglomerations or granular particles). The complex nature of multi-component high entropy materials and the differing melting temperatures, vaporization pressures, and solubility of individual species between each of the components create further challenges which do not permit scaling up laboratory- scale HEC manufacturing methods to an industrial scale. Thus, despite much interest in HEC materials and their potential industrial uses, development of a manufacturing method capable of operating on an industrial scale has been challenging, and so far, unproductive. High entropy materials have unique performance characteristics making them interesting for a variety of applications. However, there is still a need to develop technology for the manufacture of high entropy materials feedstocks in cost-effective industrial processes. Summary of the Invention A method is provided for manufacturing a high entropy carbide comprising obtaining a base feedstock comprising carbides of at least five metals and semi-metals selected from Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Ni, Cu, Zn, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Be, Mg, Ca, Sr, Ba, Al, Ga, Sn, Sb, Tl, Pb, Bi, B, Si, Ge, As, Sb, Te, and Po; wherein each of at least five members of the at least five metals and semi-metals comprises at least 5 atom% based on the total amount of metals and semi-metals; and (A) agglomerating the base feedstock, and optionally consolidating the agglomerated{P7335006585093.DOCX}-2-(v1.1) P73350 feedstock; or (B) cold crucible processing the base feedstock to obtain a melt, and solidifying the melt. Also provided is a high entropy carbide powder containing C, or a carbon source, and at least 5 metals or semi-metals selected from Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Ni, Cu, Zn, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Be, Mg, Ca, Sr, Ba, Al, Ga, Sn, Sb, Tl, Pb, Bi, B, Si, Ge, As, Sb, Te, and Po; wherein each of at least five members of the at least five metals and semi-metals comprises at least 5 atom% based on the total amount of metals and semi-metals; the carbon has a content of at least 50 atom% based on the selected metals and semi-metals; and the high entropy carbide powder has a particle size distribution of 1 µm to 4000 µm. Also provided is a spray dried powder comprising at least five metals and semi-metals selected from Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Ni, Cu, Zn, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Be, Mg, Ca, Sr, Ba, Al, Ga, Sn, Sb, Tl, Pb, Bi, B, Si, Ge, As, Sb, Te, and Po; wherein each of at least five members of the at least five metals and semi-metals comprises at least 5 atom% based on the total amount of metals and semi-metals; a carbon source; and optionally comprising at least one additive comprising a binding agent, a rheological modifier, or a surfactant; wherein the carbon source includes one or more of (a) one or more carbides of the at least five metals and semi-metals, (b) a carbon allotrope, or (c) the additive. Also provided is a composition comprising carbides of at least five metals and semi- metals selected from Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Ni, Cu, Zn, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Be, Mg, Ca, Sr, Ba, Al, Ga, Sn, Sb, Tl, Pb, Bi, B, Si, Ge, As, Sb, Te, and Po; wherein each of at least five members of the at least five metals and semi-metals comprises at least 5 atom% based on the total amount of metals and semi-metals; and wherein the composition is in the form of a cold crucible bar. In some aspects, the cold crucible bar comprises a high entropy carbide. Also provided is a method of manufacturing a high entropy carbide coating comprising obtaining a coating feedstock comprising the high entropy carbide, and applying the coating feedstock to a substrate with a thermal spray method. In some aspects, the thermal spray method comprises at least one of high velocity oxygen fuel, atmospheric plasma spray, or vacuum plasma spray. In some aspects, the base feedstock comprises carbides of at least five transition metals selected from Mo, Nb, Ti, V, W, Cr, Hf, Ta, and Zr. In some aspects, the at least 5{P7335006585093.DOCX}-3-(v1.1) P73350 metals or semimetals comprise at least five transition metals selected from Mo, Nb, Ti, V, W, Cr, Hf, Ta, and Zr. In some aspects, obtaining the high entropy carbide comprises (A). In some aspects, the agglomerating comprises spray drying. In some aspects, the agglomerating comprises consolidating, wherein the consolidating comprises sintering or plasma spheroidization. In some aspects, obtaining the high entropy carbide comprises (B). In some aspects, cold crucible processing is performed in an inert environment. In some aspects, the solidified melt is ground, milled, crushed, EIGA, or otherwise processed to obtain granules or powder. In some aspects, the high entropy carbide may be sized to obtain granules or powder. In some aspects, the powder has a particle size distribution is 2 µm to 1000 µm, or preferably 15 µm to 150 µm. In some aspects, the powder has a morphology that is spherical, angular, or a mix of spherical and angular. In some aspects, the HEC has a compositional homogeneity of ±20 at% for each of the at least 5 metals and semi-metals, and / or a compositional homogeneity of ±20 at% across any grains. In some aspects, the HC powder comprises particles having a compositional homogeneity of ±20 at% for each of the at least 5 metals and semi-metals, and / or a compositional homogeneity of ±20 at% across any grains present within the powder particles. Brief Description of the Drawings Figure 1 is an image of an HEC powder prepared with spray drying. Figure 2 is an image of another HEC powder prepared with spray drying. Figure 3 shows a HEC bar prepared by a cold crucible induction melting process, along its length (Figure 3a), from an end (Figure 3b), and a cross section (Figure 3c). Figure 4 is an X-ray diffraction pattern of a single-phase FCC HEC material. Figure 5 shows EDS scans of a bulk HEC material consolidated from spray dried HEC feedstock. Figure 5a is an overall scan of the product. Figures 5b to 5f are EDS scan results for Mo, Nb, Ti, V, and W, respectively. Dark regions are porosity in the material. Figure 6 shows EDS scans of a bulk HEC material consolidated from spray dried HEC feedstock. Figure 6a is an overall scan of the product. Figures 6b to 6f are EDS scan results for Mo, Nb, Cr, V, and W, respectively. Dark regions are porosity in the material. Figure 7 shows nanoindentation hardness measurements of the HEC feedstock with equiatomic Mo, Nb, Ti, V, and W cations. Figure 7a compares the HEC feedstock hardness, and Figure 7b plots the individual nanoindentation hardness measurements.{P7335006585093.DOCX}-4-(v1.1) P73350 Figure 8 shows nanoindentation modulus measurements of the HEC feedstock with equiatomic Mo, Nb, Ti, V, and W cations. Figure 8a compares the HEC feedstock modulus, and Figure 8b plots the individual nanoindentation modulus measurements. Figure 9 shows EDS scans of an HEC material from cold crucible induction melting process before further processing into a powder feedstock. Figure 9a is a representative electron image of the product. Figures 9b-9f are EDS linescan results for Mo, Nb, Ti, V, and W, respectively. Detailed Description Manufacturing methods such as agglomeration / sintering and cold crucible have been used to manufacture other materials. However, it had been thought that these methods were inapplicable for manufacturing HECs. (1) High Entropy Carbides: A ceramic high entropy material is represented by general formula MxDy, where M is chosen from among at least five different metallic or semi-metallic cations in an amount greater than 5 at% and D is chosen from among anions. The subscripts x and y are used to denote the ratio between cations and anions. MxDyis standard metallurgical shorthand. For example, the carbide (Cr,Mo,W,Fe)23C6 is commonly referred to as M23C6 and (TiNbTaZrHf)C is referred to as MC. As used herein, when the anion D is carbide, or is mostly carbide, e.g., at least 50% of the anion lattice, the high entropy ceramic is considered an HEC. A high entropy material contains at least 5 cationic elements in at least 5 atomic percent each. The elemental components of a high entropy material must be combined to achieve a configurational entropy of at least 1.5 times the ideal gas constant, R (8.314 J∙K-1∙mol-1), on at least one sublattice. In some embodiments, the feedstock can be a metallic material in several forms such as spherical or angular powder. In other embodiments, the powder feedstock can be composed partially or entirely of ceramics or carbides. In other embodiments, the feedstock can be a mix of ceramic and metallic materials. In of any these processing embodiments a feedstock for high entropy carbides of the form MxCy, where M represents a combination of at least 5 different carbide-forming cations, C is the anion carbon, and x and y denote the ratio of cations to anion is fabricated. Suitable carbide-forming cations include metals and semi-metals, such as Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Ni, Cu, Zn, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Be, Mg, Ca, Sr, Ba, Al, Ga, Sn, Sb, Tl, Pb, Bi, B, Si, Ge, As, Sb,{P7335006585093.DOCX}-5-(v1.1) P73350 Te, or Po. Each cation is optionally present in amounts 0-80 at% and more preferably 0-50 at%. For cations present in the base feedstock, it is more preferably 5-30 at% each. At least 5 of the metal / semi-metal cations are present in at least 5 atom% each. A carbon source may be included in the base feedstock, e.g., to account for carbon off-stoichiometry of components such as, e.g., Cr3C2 or Mo2C. A carbon source can include carbon already present in a carbide, a carbon allotrope, or carbon present in an additive. Carbon allotropes include graphite, fullerene, diamond, graphene, lonsdaleite, amorphous carbon, glassy carbon, or nanotubes, and preferably includes graphite. Additives that can act as carbon sources include a binding agent, a rheological modifier, or a surfactant. Some examples of HEC cation chemistry, with at.% based on total cation content, include: Mo 5-50 at.%, preferably 15-25 at.%; Nb 5-50 at.%, preferably 15-25 at.%; Ti 5-50 at.%, preferably 15-25 at.%; V 5-50 at.%, preferably 15-25 at.%; and W 5-50 at.%, preferably 15-25 at.%. Another example includes: Cr 5-50 at.%, preferably 15-25 at.%; Mo 5-50 at.%, preferably 15-25 at.%; Nb 5-50 at.%, preferably 15-25 at.%; V 5-50 at.%, preferably 15-25 at.%; W 5-50 at.%, preferably 15-25 at.%. Yet another example includes: Cr 0-80 at.%, preferably 0-50 at.%, more preferably 5-30 at.%; Hf 0-80 at.%, preferably 0-50 at.%, more preferably 5-30 at.%; Mo 0-80 at.%, preferably 0-50 at.%, more preferably 5-30 at.%; Nb 0-80 at.%, preferably 0-50 at.%, more preferably 5-30 at.%; Ta 0-80 at.%, preferably 0-50 at.%, more preferably 5-30 at.%; Ti 0-80 at.%, preferably 0-50 at.%, more preferably 5-30 at.%; V 0-80 at.%, preferably 0-50 at.%, more preferably 5-30 at.%; W 0-80 at.%, preferably 0-50 at.%, more preferably 5-30 at.%; and Zr 0-80 at.%, preferably 0-50 at.%, more preferably 5-30 at.%; provided that at least 5 of the cations are present in at least 5 at.% each.{P7335006585093.DOCX}-6-(v1.1) P73350 HECs preferably have a face-centered cubic (FCC) crystal structure. The crystal structure can be determined by an ordinary practitioner by methods such as X-ray diffraction (XRD). Samples of (CrMoNbVW)C and (MoNbTiVW)C produced from the feedstock as disclosed herein exhibit an FCC crystal structure. (2) Manufacturing HECs: Methods of manufacturing HECs described below can be performed on a laboratory (e.g., small batch) scale. Unlike other methods of manufacturing, methods described below are amenable to scaling up to an industrial scale, permitting HEC powders and articles to be economically produced for use in industry. (2-A) Agglomeration and Consolidation Agglomeration (e.g., by spray drying) optionally followed by consolidation (e.g., by sintering or plasma spheroidization) involves two stages. First, the components, such as metal carbides, are obtained or prepared in the form of powders, combined, and then agglomerated to form a plurality of agglomerates, the agglomerates comprising all of the feedstock components. Second, the particulate agglomerate can be consolidated into a spherical HEC powder that can then be further processed. Further processing can include aspects such as but not limited to further homogenization or a forming operation to produce a bulk HEC article. When spray drying is used, a binding agent may be used to cause or assist with agglomeration. Other optional additives may be used, such as a rheological modifier, and / or surfactant. Procedures for preparing an HEC feedstock by the spray drying method can be designed by an ordinary practitioner using the present disclosure as a reference. When used, each of these additional ingredients can be present in an amount of 0.01 to 10 vol% each in the slurry to be spray dried. For example, when the agglomeration is done by spray drying, the agglomeration feedstocks may be mixed with carrier fluid (e.g., water or volatile organic liquid) to create a slurry. A binding agent or other optional component may be included or added to the slurry. The spray dryer equipment is turned on and the drying gas is allowed to reach an appropriate temperature for evaporation of the carrier fluid. The slurry is fed through the atomization nozzle into the heated drying gas (e.g. argon or nitrogen) environment. The slurry will atomize through the nozzle and the base feedstock will agglomerate together into individual particles. Particle size can be controlled with proper selection of, e.g., nozzle diameter, slurry feed rate, and other parameters, as is known to ordinary practitioners. The carrier fluid (e.g., water or organic) will evaporate while mixing with the heated drying gas. Cyclones may be{P7335006585093.DOCX}-7-(v1.1) P73350 used to separate the particulate powder from the drying gas. The spray dried powder is optionally spheroidized and / or densified and / or sieved to a desired particle size distribution. The spray-dried powder (optionally spheroidized and / or densified) can be of any size desired. As a general matter, such powders can have particle sizes of 1 µm to 4000 µm, though most procedures and recipes will result in particle sizes in the range of 10 to 500µm (as determined by e.g., sieving, dynamic light scattering, MicroTrac, multi-laser nanoparticle tracking analysis, scanning electron microscopy, or other standard measuring techniques. The particle size distribution can be altered by tuning the spray drying parameters and / or methods of separating the powder particles such as sieving. The desired particle size distribution of the powder depends on the use for which the powder is intended, and can be determined by a person of ordinary skill in the art. Since sintering takes place below melting temperatures, the sintering process generally does not result in a significant amount of diffusion except at the particle surfaces and interfaces. Thus, it had been thought that sintering or forming an agglomerate of binary carbides that had not undergone significant particle size reduction to reduce the diffusion lengths or been mechanically alloyed (e.g., by high energy ball milling) would produce an article consisting of islands of binary carbides, with possible intermingled carbides at particle interfaces. Because little diffusion had been expected to take place, the resulting product was expected to be a low entropy carbide product. However, it has been surprisingly found that in a sintering process of binary carbide agglomerates (i.e., an HEC feedstock), much more diffusion of the cations takes place than had been expected. Indeed, it has been unexpectedly found that sufficient cation diffusion takes place to form a high entropy carbide bulk article when, for example, the HEC feedstock is formed using Field Assisted Sintering Technique (FAST). Thus, it has been unexpectedly found that sintering a base HEC feedstock (e.g., spray-dried and optionally densified material) is an effective way of forming a bulk HEC article. In some embodiments, the base feedstock for the HEC can be formed using industrial processes such as FAST, also known as Spark Plasma Sintering (SPS), into a bulk high entropy material article. For example, the base HEC feedstock can be formed using the FAST technique with a sintering temperature in the range of 800°C-5000°C, more preferably in the range of 1200°C-3000°C, and still more preferably in the range 1500°C-2300°C. In some embodiments, the base feedstock for the HEC can be applied as a high entropy carbide coating using industrial processes such as thermal spray techniques. (2-B) Cold Crucible{P7335006585093.DOCX}-8-(v1.1) P73350 The HEC feedstock product can also be produced by consolidating the material in the cold crucible induction melting process. Cold crucible induction melting is known in the art, but is believed has not to have been previously used to prepare HECs because, e.g., it would have been expected to produce multi-phase low entropy carbides and potentially result in the formation of oxide contaminants. Figure 3 shows an example of an HEC bar produced by cold crucible induction melting, and before further processing (e.g., grinding or crushing) to produce a powder feedstock. The product of the cold crucible induction melting process is preferably prepared to a desired particle size distribution, such as by electrode induction melting gas atomization (EIGA) or milling or grinding. The result of the milling and / or grinding process is preferably a powder. The desired particle size distribution of the powder depends on the use for which the powder is intended, and can be determined by a person of ordinary skill in the art. Some possible size distributions include 1 µm to 500 µm, or 15 µm to 150 µm, as measured by, e.g., MicroTrac, sieving, or dynamic light scattering. In some embodiments, the particle size distribution is more narrow. In some embodiments, the milled and or ground powder is then spheroidized. Specific procedures for preparing an HEC by the cold crucible method can be designed by an ordinary practitioner using the present disclosure as a reference. General guidelines include determining blend ratios for the powders to be combined. If the powders are coarse (e.g., greater than or about 45 micrometers), it may be advantageous to blend them. If the powders are fine (e.g., less than or about 45 micrometers), it may be advantageous to pelletize them to 45 to 3000 micrometers. The blended powder or pellets are added to the CCI reaction chamber. The process is preferably performed in an inert environment, such as argon, to reduce or prevent oxidation. The initial material is allowed to melt, preferably fully melt. More powder or pellets are then fed in while removing the melted material from the melt zone. Each material generally will require a different feeding rate based on its melting behavior. For carbides, a feed rate of about 100 g / min is generally suitable, though this can be modified. The feed rate can be adjusted by an ordinary practitioner based on a number of factors, such as crucible size and temperature, powder / pellet size, and specific materials used. As the material is moved out of the melt zone, the melted material cools and solidifies to form, e.g., a bar. The process is continued until the desired amount of powder / pellets are used, or the desired bar length is achieved. A full bar is a bar with a diameter determined by the diameter{P7335006585093.DOCX}-9-(v1.1) P73350 of the melting crucible and a length allowed by equipment setup, and the precise dimensions are not critical. A typical diameter can be 30 to 50 mm, and a typical bar length can be about 600 mm. Other diameters and lengths can be obtained depending on, e.g., equipment used and plant set-up. Potentially, the diameter could be up to about 80 mm (or more) and a length could be several meters. For ease of processing, the length is preferably not so great that the bar breaks during the cold crucible induction part of the manufacturing process. Once the bar cools sufficiently to safely handle, e.g., about room temperature, it can be retrieved, then further processed based on the intended use. Thus, the bar could be left as is; broken into several large pieces; cut or shaped into pieces, milled to, e.g., submicron size particles; or anything in between. Typically, however, the bar will be advantageously broken into chunks, then crushed and milled to obtain a desired particle size distribution. Variations of the above procedures can be devised without departing from the scope of the present disclosure. (3) Material Properties HEC materials encompassed within this disclosure include HEC feedstocks which can be used to prepare articles such as coatings. Also included are HEC articles made from the HEC feedstocks, such as coatings. As opposed to a carbide that is not a high entropy material, an HEC is characterized by homogeneity of the 5+ cation material, particularly of the cations or cation sublattice. In some embodiments, when measured by, e.g., EDS, an HEC feedstock or article should exhibit compositional homogeneity (±20 at% per cation, preferably ±10 at%, and still more preferably ±5 at%) across the sample, and / or within grains that may be present. Compositional homogeneity can be determined by any suitable method, such as energy- dispersive X-ray spectroscopy (EDS), such as demonstrated in T.J. Harrington, et al., Acta Materialia, 166:271-280 (March 2019). The configurational entropy of an HEC material can be determined by methods known in the art, such as described in Dippo et al. (“A universal configurational entropy metric for high-entropy materials,” Scripta Materialia 201 (2021) 113974). The HEC material preferably has a configurational entropy of at least 1.5 times the ideal gas constant, R (8.314 J∙K-1∙mol-1), on at least one sublattice, e.g., the cation sublattice. HEC articles prepared from HEC feedstocks exhibit high indentation hardness and modulus. Nanoindentation hardness and modulus can be measured by an ordinary practitioner with any suitable method, such as ISO 14577 or ASTM E 2546. Some preferred{P7335006585093.DOCX}-10-(v1.1) P73350 hardness values include 5-60 GPa and more preferably 15-40 GPa. Some preferred modulus values are 300-600 GPa. Examples Example 1 Examples of HEC feedstock produced by spray drying are shown in Figures 1 and 2. Figure 1 shows the spray dried powder example with chemistry (MoNbTiVW)C and Figure 2 shows the spray dried powder example with chemistry (MoNbCrVW)C. Each example was prepared applying the following recipe. Binary carbide powders of about 3µm size were blended together and mixed with a carrier fluid and binding agent. A peristaltic pump fed the slurry into the spray drying equipment where it was picked up by a carrier gas with inlet temperature of 200°C and outlet temperature of 130°C. Agglomerated particles of HEC feedstock were collected using a cyclone. Figures 5 and 6 is an EDS of a bulk HEC product made from spray dried HEC feedstock (feedstock shown in Figures 1 & 2; respectively). Each feedstock was consolidated into a bulk using the FAST technique to demonstrate homogeneity achieved in a product produced from this powder. Example 2 An example of an HEC bar produced using cold crucible induction is shown in Figure 3. This example using (MoNbTiVW)C as an example chemistry was produced using the following manufacturing procedures. The individual binary carbide powders were sieved to a preferred size distribution of 10 to 18 µm and then pelletized. A 50mm dovetail graphite was utilized as the starter in the cold crucible process. Argon was used to keep the chamber inert. Pellets were fed into the cold crucible induction equipment with intermittent pulling on the graphite starter until the bar reached about 18 inches length. Figure 9a, an electron image, and Figures 9b-9f, example EDS linescans of the CCI bar shown in Figure 3 before being ground into a powder, illustrates the bar’s homogeneity within and between grains. Nanoindentation hardness values for (MoNbTiVW)C cold crucible feedstock are shown in Figure 7. Figure 7a compares the HEC feedstock hardness, marked with a five- pointed star, to the nanoindentation hardness and Rule of Mixtures (ROM) reported in T.J.{P7335006585093.DOCX}-11-(v1.1) P73350 Harrington, et al., Acta Materialia, 166:271-280 (March 2019). Figure 7b plots the individual nanoindentation hardness measurements. Nanoindentation modulus values for (MoNbTiVW)C cold crucible feedstock are shown in Figure 8. Figure 8a compares the HEC feedstock modulus, and marked with a five- pointed star, to the nanoindentation modulus of binary and high entropy carbides as reported in W. M. Mellor, et al., Journal of the European Ceramic Society, 41:5791-5800 (September 2021). Figure 7b plots the individual nanoindentation modulus measurements. The VEC values in Figures 7a and 8a indicate the nominal number of valence electrons per formula unit for each composition. The five-pointed stars in Figures 7a and 8a are the material properties measured for the CCI bar (Figure 3), and the remaining data are from values reported in literature (~4g “bulk” samples consolidated by FAST from high energy ball milled powder). Figures 7b and 8b show the approximately 170 individual measurements for the respective property. Hardness and modulus measurements are performed at room temperature in accordance with ISO standard 14577 with 300 mN applied force. The nanoindentation indents are spaced 50 µm apart to avoid stress effects from nearby indents. Sample surfaces were prepared for nanoindentation testing using standard metallographic procedures and can be modified by an ordinary practitioner using the present disclosure as a reference: grinding using SiC papers from 80 to 1200 grit, polishing using 3μm and 1μm diamond suspensions, and final polishing with a 0.04μm colloidal silica solution. Samples can be vibratory polished using 0.05 µm colloidal silica for 12 h to further minimize surface roughness.{P7335006585093.DOCX}-12-(v1.1)

Claims

P73350 Claims 1. A method of manufacturing a high entropy carbide comprising: obtaining a base feedstock comprising carbides of at least five metals and semi-metals selected from Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Ni, Cu, Zn, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Be, Mg, Ca, Sr, Ba, Al, Ga, Sn, Sb, Tl, Pb, Bi, B, Si, Ge, As, Sb, Te, and Po; wherein each of at least five members of the at least five metals and semi-metals comprises at least 5 atom% based on the total amount of metals and semi-metals; and (A) agglomerating the base feedstock, and optionally consolidating the agglomerated feedstock; or (B) cold crucible processing the base feedstock to obtain a melt, and solidifying the melt.

2. The method of claim 1, wherein the base feedstock comprises carbides of at least five transition metals selected from Mo, Nb, Ti, V, W, Cr, Hf, Ta, and Zr.

3. The method of claim 1, wherein the obtaining of the high entropy carbide comprises (A).

4. The method of claim 3, wherein the agglomerating comprises spray drying.

5. The method of claim 3, comprising the consolidating, wherein the consolidating comprises sintering or plasma spheroidization.

6. The method of claim 1, wherein the obtaining of the high entropy carbide comprises (B).

7. The method of claim 6, comprising the cold crucible processing in an inert environment.

8. The method of claim 6, wherein the solidified melt is ground, milled, crushed, EIGA, or otherwise processed to obtain granules or powder.{P7335006585093.DOCX}-13-(v1.1)P73350 9. The method of claim 1, further comprising sizing the high entropy carbide to obtain granules or powder.

10. A method of manufacturing a high entropy carbide coating comprising obtaining a coating feedstock comprising the high entropy carbide of claim 1, and applying the coating feedstock to a substrate with a thermal spray method.

11. The method of claim 10, wherein the thermal spray method comprises at least one of high velocity oxygen fuel, atmospheric plasma spray, or vacuum plasma spray.

12. A high entropy carbide powder containing C, or a carbon source, and at least 5 metals or semi-metals selected from Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Ni, Cu, Zn, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Be, Mg, Ca, Sr, Ba, Al, Ga, Sn, Sb, Tl, Pb, Bi, B, Si, Ge, As, Sb, Te, and Po; wherein each of at least five members of the at least five metals and semi-metals comprises at least 5 atom% based on the total amount of metals and semi-metals; the carbon has a content of at least 50 atom% based on the selected metals and semi- metals; and the high entropy carbide powder has a particle size distribution of 1 µm to 4000 µm.

13. The powder of claim 12 wherein the particle size distribution is 2 µm to 1000 µm, or preferably 15 µm to 150 µm.

14. The powder of claim 12 wherein the powder has a morphology that is spherical, angular, or a mix of spherical and angular.

15. The powder of claim 12 wherein the at least 5 metal or semi-metals are selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W.

16. The powder of claim 12 wherein the powder comprises particles having a compositional homogeneity of ±20 at% for each of the at least 5 metals and semi-metals, and / or a compositional homogeneity of ±20 at% across any grains present within the powder particles.

17. A spray dried powder comprising:{P7335006585093.DOCX}-14-(v1.1)P73350 at least five metals and semi-metals selected from Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Ni, Cu, Zn, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Be, Mg, Ca, Sr, Ba, Al, Ga, Sn, Sb, Tl, Pb, Bi, B, Si, Ge, As, Sb, Te, and Po; wherein each of at least five members of the at least five metals and semi-metals comprises at least 5 atom% based on the total amount of metals and semi-metals; a carbon source; and optionally comprising at least one additive comprising a binding agent, a rheological modifier, or a surfactant; wherein the carbon source includes one or more of (a) one or more carbides of the at least five metals and semi-metals, (b) a carbon allotrope, or (c) the additive.

18. A composition comprising: carbides of at least five metals and semi-metals selected from Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Re, Fe, Ru, Co, Ni, Cu, Zn, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Be, Mg, Ca, Sr, Ba, Al, Ga, Sn, Sb, Tl, Pb, Bi, B, Si, Ge, As, Sb, Te, and Po; wherein each of at least five members of the at least five metals and semi-metals comprises at least 5 atom% based on the total amount of metals and semi-metals; and wherein the composition is in the form of a cold crucible bar.

19. The composition of claim 18, wherein the cold crucible bar comprises a high entropy carbide.{P7335006585093.DOCX}-15-(v1.1)

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