WO2023091595A1 - Alliages à entropie moyenne à élevée et leurs procédés de fabrication - Google Patents

Alliages à entropie moyenne à élevée et leurs procédés de fabrication Download PDF

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WO2023091595A1
WO2023091595A1 PCT/US2022/050295 US2022050295W WO2023091595A1 WO 2023091595 A1 WO2023091595 A1 WO 2023091595A1 US 2022050295 W US2022050295 W US 2022050295W WO 2023091595 A1 WO2023091595 A1 WO 2023091595A1
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high entropy
oxide
medium
entropy alloy
metal
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PCT/US2022/050295
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English (en)
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Helen M. Chan
Animesh Kundu
Madison GIANELLE
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Lehigh University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/16—Making metallic powder or suspensions thereof using chemical processes
    • B22F9/18—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds
    • B22F9/20—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds
    • B22F9/22—Making metallic powder or suspensions thereof using chemical processes with reduction of metal compounds starting from solid metal compounds using gaseous reductors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/04—Making non-ferrous alloys by powder metallurgy
    • C22C1/0433—Nickel- or cobalt-based alloys
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C30/00—Alloys containing less than 50% by weight of each constituent
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/04—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling
    • B22F2009/043—Making metallic powder or suspensions thereof using physical processes starting from solid material, e.g. by crushing, grinding or milling by ball milling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
    • B22F2998/10—Processes characterised by the sequence of their steps

Definitions

  • High entropy alloys also known as multi-principal elemental alloys (MPEAs) or multicomponent alloys (MCAs)
  • MPEAs multi-principal elemental alloys
  • MCAs multicomponent alloys
  • a high entropy alloy often refer to a multi-component single phase alloys formed by the reduction of total free energy of the solid solution single phase due to a significant increase in configuration entropy of the multi- component system, prohibiting the formation of intermetallic compounds.
  • a high- entropy alloy refers not to an intermetallic compound or an amorphous alloy, but to a stable single- phase multi-component alloy.
  • high entropy alloys differ from conventional alloys in that they incorporate a high number of elemental components in significant (near equiatomic) proportions. Study of high entropy alloys, therefore, represents a radical departure from conventional alloy design strategies, which focus on a single primary component, with the addition of minor quantities of other elements. It is clear that one significant consequence of the HEA concept is the astronomically high number of possible compositions.
  • High entropy alloys are typically produced by arc-melting, although methods for forming a layer of high entropy alloy using a laser beam have been a recent focus of developed.
  • the arc- melting process has merits in that it is easy to form a homogenous solid solution, the generation of contaminant elements, such as oxides and voids, is minimized compared to a sintering process, and the ductility-brittleness transition temperature (DBTT) of the composition is relatively lower in the arc-melting process than in the sintering process, thus increasing the rupture time.
  • DBTT ductility-brittleness transition temperature
  • Another method for producing high entropy alloys includes casting processes, in which the raw-material metal is melted, and high temperature/high pressures are used for sintering, such as spark plasma sintering or hot isostatic pressing of raw materials.
  • the raw material for casting processes are typically highly pure metal powders.
  • a method for producing a medium to high entropy alloy comprising mixing a feed composition to obtain a metal oxide mixture, wherein the feed composition comprises four or more metal oxides selected from alkali metal oxides, alkaline earth metal oxides, lanthanoid oxides, actinoid oxides, transition metal oxides, and post-transition metal oxides; and heat treating of the metal oxide mixture by annealing at a temperature of about 900 to about 1600 °C for an annealing time of about 10 to about 260 hours in an atmosphere comprising hydrogen and at least one of nitrogen, argon, or a combination thereof.
  • a medium to high entropy alloy having a composition comprising a plurality of metals; and a micro structure comprising a metal phase, a metal oxide phase, or a combination thereof.
  • the plurality of metals of the composition comprises four or more metals present in a mass fraction of about 0.05 or more.
  • a method for producing a medium to high entropy alloy comprising mixing a feed composition to obtain a metal oxide mixture, wherein the feed composition comprises four or more metal oxides selected from alkali metal oxides, alkaline earth metal oxides, lanthanoid oxides, actinoid oxides, transition metal oxides, post-transition metal oxides, or a combination of two or more thereof; and reducing the metal oxide mixture to produce a medium to high entropy alloy.
  • FIG. 1A is an image of the microstructure of an example medium to high entropy alloy in accordance with aspects of the invention
  • FIG. IB is an image of the microstructure of another example medium to high entropy alloy having a metal layer and a metal oxide layer according to aspects of the invention.
  • FIG. 2 is an image of a compositional Energy Dispersive X-ray Spectroscopy map of a further example medium to high entropy alloy in accordance with aspects of the invention
  • FIG. 3 is a graph of a representative X-ray diffraction spectra obtained from two example medium to high entropy alloys having a metal layer and a metal oxide layer according to aspects of the invention.
  • FIG. 4 is an image of a compositional Energy Dispersive X-ray Spectroscopy map of an example medium to high entropy alloy in accordance with aspects of the invention.
  • any reference to direction or orientation is merely intended for convenience of description and is not intended in any way to limit the scope of the present invention.
  • Relative terms such as “lower,” “upper,” “horizontal,” “vertical,” “above,” “below,” “up,” “down,” “top,” and “bottom” as well as derivative thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description only and do not require that the apparatus be constructed or operated in a particular orientation.
  • ranges are used as shorthand for describing each and every value that is within the range. Any value within the range can be selected as the terminus of the range. Thus, a range from 1-5, includes specifically 1, 2, 3, 4 and 5, as well as subranges such as 2-5, 3-5, 2-3, 2-4, 1-4, etc.
  • the term “about” when referring to a number means any number within a range of 10% of the number.
  • the phrase “about 2 wt.%” refers to a number between and including 1.8 wt.% and 2.2 wt.%.
  • any member in a list of species that are used to exemplify or define a genus may be mutually different from, or overlapping with, or a subset of, or equivalent to, or nearly the same as, or identical to, any other member of the list of species. Further, unless explicitly stated, such as when reciting a Markush group, the list of species, compounds, components, and/or elements that define or exemplify the genus is open, and it is given that other species may exist that define or exemplify the genus just as well as, or better than, any other species listed.
  • D, E, and F can be included.
  • it is equivalent to the phrase “one or more elements selected from the group consisting of A, B, C, D, E, F, and a mixture of any two or more of A, B, C, D, E, and F.”
  • the term “an oxide thereof’ also relates to “oxides thereof.”
  • the disclosure refers to “an element selected from the group consisting of A, B, C, D, E, F, an oxide thereof, and a mixture thereof,” it indicates that that one or more of A, B, C, D, and F may be included, one or more of an oxide of A, an oxide of B, an oxide of C, an oxide of D, an oxide of
  • E, and an oxide of F may be included, or a mixture of any two of A, B, C, D, E, F, an oxide of A, an oxide of B, an oxide of C, an oxide of D, an oxide of E, and an oxide of F may be included.
  • the medium to high entropy alloys of the instant disclosure can be free or essentially free of all components and elements positively recited throughout the instant disclosure.
  • the medium to high entropy alloys of the present disclosure may be substantially free of non-incidental and/or non-trace amounts of the ingredient(s) or compound(s) described herein.
  • a non-incidental and/or non-trace amount of an ingredient or compound is the amount of that ingredient or compound that is added into the composition of the medium to high entropy alloys by itself.
  • Some of the various categories of components identified may overlap. In such cases where overlap may exist and the medium to high entropy alloy includes both components (or the composition includes more than two components that overlap), an overlapping compound does not represent more than one component.
  • High entropy alloy conventionally applies to alloys having a high level of internal disorder that occurs when the principal elements of such alloys are mixed. Typically, when several metals are combined, enthalpy drives them towards forming intermetallic compounds that are hard and brittle. By increasing the relative proportions of the elements and introducing more internal entropy, the formation of such compounds becomes energetically much less favorable, which is conventionally believed to give the resultant alloys improved physical properties without the drawbacks of conventional mixtures.
  • certain methods can reduce feed compositions comprising a manganese metal oxide at processing conditions that would be expected to be unable to reduce such manganese metal oxide.
  • certain methods can reduce feed compositions comprising a chromium metal oxide at processing conditions that would be expected to be unable to reduce such chromium metal oxide.
  • a medium to high entropy alloy refers to an alloy comprising four or more metal components, where none of the metal components comprise more than 50 wt.% of the alloy and at least four of the metal components are present in an amount of more than 5 wt.%, based on the total weight of the medium to high entropy alloy.
  • a method for producing a medium to high entropy alloy comprising mixing a feed composition to obtain a metal oxide mixture, wherein the feed composition comprises four or more metal oxides selected from alkali metal oxides, alkaline earth metal oxides, lanthanoid oxides, actinoid oxides, transition metal oxides, post-transition metal oxides, or a combination of two or more thereof; and heat treating of the metal oxide mixture by annealing at a temperature of about 900 to about 1600 °C for an annealing time of about 10 to about 260 hours in an atmosphere comprising hydrogen and at least one of nitrogen, argon, or a combination thereof.
  • a medium to high entropy alloy having a composition comprising a plurality of metals, the plurality of metals comprising four or more metals present in a mass fraction of about 0.05 or more; and a micro structure comprising a metal phase, a metal oxide phase, or a combination thereof.
  • a method for producing a medium to high entropy alloy comprising mixing a feed composition to obtain a metal oxide mixture, wherein the feed composition comprises four or more metal oxides selected from alkali metal oxides, alkaline earth metal oxides, lanthanoid oxides, actinoid oxides, transition metal oxides, post-transition metal oxides or a combination of two or more thereof; and reducing the metal oxide mixture to produce a medium to high entropy alloy.
  • the feed composition of the method typically comprises four or more metal oxides selected from alkali metal oxides, alkaline earth metal oxides, lanthanoid oxides, actinoid oxides, transition metal oxides, post-transition metal oxides, and a combination of two or more thereof. While the feed composition typically comprises four or more metal oxides, in some embodiments the feed composition includes a plurality of metal oxides comprising five, six, seven, eight, nine, or any range or subrange formed therefrom, of metal oxides.
  • the feed composition may comprise a plurality of metal oxides comprising from 4 to 9, 4 to 8, 4 to 7, 4 to 6, 4 or 5; from 5 to 9, 5 to 8, 5 to 7, 5 or 6; from 6 to 9, 6 to 8, or 6 or 7 of metal oxides.
  • the feed composition may be comprised of about 50 wt.% or more of metal oxides, based on the total weight of the feed composition.
  • the feed composition may be comprised of about 60 wt.% or more, about 70 wt.% or more, about 80 wt.% or more, about 85 wt.% or more, about 88 wt.% or more, about 90 wt.% or more, about 92 wt.% or more, about 94 wt.% or more, about 96 wt.% or more, or about 98 wt.% or more of metal oxides, based on the total weight of the feed composition.
  • the feed composition comprises about 99 wt.% or about 100 wt.%, with or without trace elements, of metal oxides.
  • the feed composition may include a plurality of metal oxides of four or more metal oxides selected from alkali metal oxides, alkaline earth metal oxides, lanthanoid oxides, actinoid oxides, transition metal oxides, post-transition metal oxides, and a combination of two or more thereof.
  • One or more of the metal oxides may be selected from the same group of earth metal oxides, lanthanoid oxides, actinoid oxides, transition metal oxides, or post-transition metal oxides.
  • at least two, at least three, or at least four of the plurality of metal oxides may be selected from same group of earth metal oxide, lanthanoid oxide, actinoid oxide, transition metal oxide, or post-transition metal oxide.
  • two or more of the metal oxides may be selected from a different groups of earth metal oxides, lanthanoid oxides, actinoid oxides, transition metal oxides, or post-transition metal oxides. In some embodiments, at least three, at least four, at least five of the plurality of metal oxides may be selected from different groups of earth metal oxides, lanthanoid oxides, actinoid oxides, transition metal oxides, or post-transition metal oxides.
  • the plurality of metal oxides of the feed composition may include at least one metal oxide of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), francium (Fr), or a combination of two or more thereof.
  • the plurality of metal oxides may include at least one metal oxide of Na, K, Rb, Cs, Fr, or a combination of two or more thereof.
  • the plurality of metal oxides may include at least one metal oxide of beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), or a combination of two or more thereof.
  • the plurality of metal oxides may include at least one metal oxide of Mg, Sr, Ba, Ra, or a combination of two or more thereof.
  • the plurality of metal oxides may include at least one metal oxide of lanthanum (Ln), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), or a combination of two or more thereof.
  • Ln lanthanum
  • Ce cerium
  • Pr praseodymium
  • Nd neodymium
  • Pm promethium
  • Sm samarium
  • Eu europium
  • Gd gadolinium
  • Tb terbium
  • Dy dysprosium
  • Ho holmium
  • Er erbium
  • Tm thulium
  • Yb lute
  • the plurality of metal oxides may, additionally or alternatively, include at least one metal oxide of actinium (Ac), thorium (Th), protactinium (Pa), uranium (U), neptunium (Np), plutonium (Pu), americium (Am), curium (Cm), berkelium (Bk), californium (Cf), einsteinium (Es), fermium (Fm), mendelevium (Md), nobelium (No), lawrencium (Lr), or a combination of two or more thereof.
  • the plurality of metal oxides may include at least one metal oxide of Ac, Th, Pa, Np, Am, Cm, Bk, Cf, Es, Fm, Md, No, Lr, or a combination of two or more thereof.
  • the plurality of metal oxides may include at least one metal oxide of scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (O
  • the plurality of metal oxides may include at least one metal oxide of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, W, Pt, Au, Hg, Rf, Mt, Ds, Rg, Cn, or a combination of two or more thereof.
  • the plurality of metal oxides may include at least one metal oxide of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Rh, Pd, Ag, Hf, W, Pt, Au, or a combination of two or more thereof.
  • the plurality of metal oxides may include at least one metal oxide of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Pd, Ag, W, Pt, Au, or a combination of two or more thereof.
  • the plurality of metal oxides may include at least one metal oxide of indium (In), aluminum (Al), lead (Pb), gallium (Ga), bismuth (Bi), Thallium (TI), tin (Sn), polonium (Po), or a combination of two or more thereof.
  • the plurality of metal oxides may include at least one metal oxide of In, Al, Pb, Ga, TI, Sn, or a combination of two or more thereof. In some cases, the plurality of metal oxides may include at least one metal oxide of Al, Pb, Sn, or a combination of two or more thereof.
  • the method may include a feed composition having certain metal oxides depending on the desired application of the medium to high entropy alloy and/or the desired properties thereof.
  • the plurality of metal oxides of the feed composition may comprise 4 and 9 metal oxides selected from metal oxides of Co, Ni, Fe, Cr, Mn, Ti, V, Zn, Cu, Mg, Al, Mo, Ir, Nb, Ga, Ge, Sr, Y, Zr, Rh, Pd, Ag, Sn, Sb, Hf, Ta, Pt, Au, and a combination of two or more thereof.
  • the feed composition comprises 4 and 9 metal oxides chosen from oxides of Cr, Fe, V, Al, Si, Mn, Mo, Ti, Ni, and a mixture of two or more thereof.
  • the feed composition comprises a plurality of metal oxides selected from oxides of Co, Ni, Cu, Rh, Ir, Zr, and a combination of two or more thereof.
  • the four or more metal oxides are selected from a cobalt oxide, a nickel oxide, an iron oxide, a chromium oxide, a manganese oxide, a titanium oxide, a vanadium oxide, a zinc oxide, a copper oxide, a magnesium oxide, and a combination of two or more thereof.
  • the feed composition may comprise a chromium oxide, a manganese oxide, a cobalt oxide, a nickel oxide, an iron oxide, or a combination of two or more thereof.
  • the feed composition may comprise cobalt oxide, chromium oxide, iron oxide, nickel oxide, niobium oxide, or a combination of two or more thereof.
  • the manganese oxides may be selected from MnO, Mn 2 O 3 , Mn 3 O 4 , MnO 2 , Mn 5 O 8 , or a combination of two or more thereof.
  • chromium oxides include CrO, Cr 2 O 3 , CrO 2 , CrO 3 , CrO 5 , Cr 8 O 21 , or a combination of two or more thereof.
  • nickel oxide include NiO, Ni 2 O 3 , or a combination of two or more thereof.
  • cobalt oxides include CoO, CO 2 O, CO 3 O, or a combination of two or more thereof.
  • iron oxides include FeO, Fe 3 O 4 , Fe 4 O 5 , Fe 5 O 6 , Fe 5 O 7 , Fe 25 O 32 , Fe 13 O 19 , ⁇ -Fe 2 O 3 , ⁇ -Fe 2 O 3 , ⁇ -Fe 2 O 3 , ⁇ -Fe 2 O 3 , or a combination of two or more thereof.
  • the metal oxides may individually be present in the feed composition in an amount from about 5 to about 35 wt.%, based on the total weight of the feed composition.
  • the metal oxides may be individually present in the feed composition in an amount from about 5 to about 35 wt.%, about 5 to about 32 wt.%, about 5 to about 29 wt.%, about 5 to about 27 wt.%, about 5 to about 25 wt.%, about 5 to about 23 wt.%, about 5 to about 21 wt.%, about 5 to about 19 wt.%, about 5 to about 17 wt.%; from about 10 to about 35 wt.%, about 10 to about 32 wt.%, about 10 to about 29 wt.%, about 10 to about 27 wt.%, about 10 to about 25 wt.%, about 10 to about 23 wt.%, about 10 to about 21 wt.%, about 10 to about 19 wt.%, about 10 to about 17 wt.%
  • each of the plurality of metal oxides in the feed composition is present in an amount from about 5 to about 35 wt.%, including any of the ranges discussed in above, based on the total weight of the feed composition.
  • the feed composition may be formulated to have a plurality of metal oxides in certain weight ratios.
  • the feed composition may be formulated such that each metal oxide has a weight ratio of about 1:3 to about 3:1, relative to any other individual metal oxide.
  • the weight ratio of each metal oxide to any other individual metal oxide of the plurality of metal oxides is about 1:3 to about 3:1, about 1:2 to about 3:1, about 1:1 to about 3:1; about 1:3 to about 2:1, about 1:3 to about 1:1, or any range or subpage thereof.
  • the methods for producing a medium to high entropy alloy typically comprise mixing a feed composition to obtain a metal oxide mixture.
  • the feed composition may be mixed by milling, blending, and/or stirring the feed composition.
  • the feed composition may be mixed by milling, including ball milling.
  • the methods may further comprise reducing the metal oxide mixture.
  • the metal oxide mixture may be reduced completely or partially.
  • the method may be adapted to produce a medium to high entropy alloy having a micro structure comprising a metal oxide, whereby the method is adapted to partially reduce the metal oxide mixture.
  • the method is adapted to completely reduce the metal oxide mixture and produce a medium to high entropy alloy having a micro structure that is free or essentially free of metal oxides.
  • the methods may be adapted to partially reduce the metal oxide mixture, such about 30 to about 95%, of the metal oxides in the metal oxide mixture is reduced.
  • the method may partially reduce the metal oxide mixture, such that about 40 to about 95%, about 50 to about 95%, about 60 to about 95%, about 70 to about 95%; about 40 to about 85%, about 50 to about 85%, about 60 to about 85%; about 40 to about 75%, about 50 to about 75%, about 60 to about 75%; about 40 to about 65%, about 50 to about 65%, or any range or subrange formed therefrom, of the metal oxides in the metal oxide mixture is reduced.
  • the metal oxide mixture may be reduced by heat treating of the metal oxide mixture.
  • the heat treatment is an isothermal heat treatment, such that the method comprises isothermal heat treating of the metal oxide mixture.
  • the methods may include heat treating of the metal oxide mixture by annealing at a temperature of about 900 to about 1600 °C for an annealing time of about 10 to about 260 hours in an atmosphere comprising hydrogen and at least one of nitrogen, argon, or a combination thereof.
  • the annealing may be at a temperature of about 900 to about 1600 °C, about 900 to about 1500 °C, about 900 to about 1400 °C, about 900 to about 1300 °C, about 900 to about 1200 °C, about 900 to about 1100 °C; from about 1,000 to about 1600 °C, about 1,000 to about 1500 °C, about 1,000 to about 1400 °C, about 1,000 to about 1300 °C, about 1,000 to about 1200 °C, about 1,000 to about 1100 °C; from about 1,050 to about 1600 °C, about 1,050 to about 1500 °C, about 1,050 to about 1400 °C, about 1,050 to about 1300 °C, about 1,050 to about 1200 °C, about 1,050 to about 1100 °C; from about 1,100 to about 1600 °C, about 1,100 to about 1500 °C, about 1,100 to about 1400 °C, about 1,100 to about 1300 °C, about 1,050 to
  • the method may include annealing at a temperature of about 900 to about 1,500 °C, about 1,000 to about 1,400 °C, about 1,000 to about 1,300 °C, about 1,100 to about 1600 °C, about 1150 to about 1300 °C, or about 1180 to about 1600 °C.
  • the annealing may occur for an amount of time that may vary, but typically in the range of from about 10 to about 260 hours, including terminal endpoints.
  • the method includes an annealing time of about 10 to about 260 hours, about 10 to about 220 hours, about 10 to about 180 hours, about 10 to about 140 hours, about 10 to about 120 hours, about 10 to about 100 hours, about 10 to about 80 hours, about 10 to about 60 hours, about 10 to about 48 hours, about 10 to about 36 hours, about 10 to about 24 hours; from about 20 to about 260 hours, about 20 to about 220 hours, about 20 to about 180 hours, about 20 to about 140 hours, about 20 to about 120 hours, about 20 to about 100 hours, about 20 to about 80 hours, about 20 to about 60 hours, about 20 to about 48 hours, about 20 to about 36 hours; from about 30 to about 260 hours, about 30 to about 220 hours, about 30 to about 180 hours, about 30 to about 140 hours, about 30 to about 120 hours, about 30 to about 100 hours, about 30 to about 30
  • the method typically includes annealing of the metal oxide mixture in an atmosphere comprising hydrogen and at least one of nitrogen, argon, or a combination thereof.
  • the atmosphere for annealing consists of one or more of hydrogen and at least one of nitrogen, argon, or a combination thereof, with or without trace elements.
  • the method includes annealing of the metal oxide mixture in an atmosphere comprising about 1 to 4.5 mol.% of hydrogen and about 95.5 mol.% or more of argon and/or nitrogen.
  • the annealing of the metal oxide mixture may be in an atmosphere having from about 1 to 4 mol.%, about 1 to 3.5 mol.%, about 1 to 3 mol.%, about 1 to 2.5 mol.%; from about 1.5 to 4.5 mol.%, about 1.5 to 4 mol.%, about 1.5 to 3.5 mol.%, about 1.5 to 3 mol.%, about 1.5 to 2.5 mol.%; from about 2 to 4.5 mol.%, about 2 to 4 mol.%, about 2 to 3.5 mol.%, about 2 to 3 mol.%; from about 2.5 to 4.5 mol.%, about 2.5 to 4 mol.%, about 2.5 to 3.5 mol.%; from about 3 to 4.5 mol.%, about 3 to 4 mol.%, or any range or subrange thereof, of hydrogen, based on the total composition of the atmosphere for annealing of metal oxide mixture, with the remainder being argon and/or nitrogen, with or without trace elements.
  • the annealing of the metal oxide mixture may be in an atmosphere having about 95.5 mol.% or more, about 96 mol.% or more, about 96.5 mol.% or more, about 97 mol.% or more, about 97.5 mol.% or more, about 98 mol.% or more, about 98.5 mol.% or more of argon and/or nitrogen, with or without trace elements.
  • the atmosphere for annealing consists of hydrogen in any of the amounts discussed above and argon in any of the amount discussed above, with or without trace elements.
  • the atmosphere for annealing generally includes hydrogen and at least one of argon, nitrogen, or a combination thereof, in some embodiments the atmosphere consists of hydrogen.
  • the methods disclosed herein may optionally include shaping the metal oxide mixture prior to heat treating.
  • the method may include disposing the metal oxide mixture into a container having a predetermined shape prior to the heat treatment to ultimately produce a medium to high entropy alloy having a form corresponding to the predetermined shape.
  • the metal oxide can be positioned in a container having a shape that is substantially geometric or geometric (e.g., as a square, rectangle, orthogonal, rhombus, trapezoid, spherical, or the like) or a shape corresponding to a pellet, a bar, a sheet, or the like.
  • the method is adapted to produce a medium to high entropy alloy in the form of a pellet, a bar, a sheet, a powder, or the like.
  • the methods disclosed herein may include sintering at least a section of the metal material during the heat treatment.
  • the method may include a heat treatment that sinters a section (e.g., a layer) of the metal oxide material undergoing heat treatment, e.g., such that the medium to high entropy alloy includes at least one section that underwent sintering.
  • the method includes sintering the whole metal oxide material during heat treatment to produce a medium to high entropy alloy that underwent sintering.
  • the section and/or amount of the medium to high entropy alloy that was sintered during the method may depend on the form/shape of the material during heat treatment.
  • the method may include producing a medium to high entropy alloy having a first section and a second section that is different from the first section.
  • the method may include producing a medium to high entropy alloy in the form of a sheet, wherein the medium to high entropy alloy has a first layer and a second layer that is different from the first layer.
  • the first section and/or first layer has a microstructure comprising a metal phase and the second section and/or second layer has a microstructure comprising a metal oxide phase.
  • a medium to high entropy alloy may be produced according to the methods described herein.
  • the medium to high entropy alloys disclosed herein, including those produced according to the methods described herein, may be adapted for aerospace materials, nuclear reactor materials, electronic components and/or materials, circuitry components and/or materials, biomedical components, and the like.
  • the medium to high entropy alloy typically comprises a composition having a plurality of metals comprising four or more metals present in a mass fraction of about 0.05 or more.
  • the medium to high entropy alloy typically comprises four or more metal
  • the composition of the medium to high entropy alloy comprises five, six, seven, eight, nine, or any range or subrange formed therefrom, of metals.
  • the composition may comprise a plurality of metal comprising from 4 to 9, 4 to 8, 4 to 7, 4 to 6, 4 or 5; from 5 to 9, 5 to 8, 5 to 7, 5 or 6; from 6 to 9, 6 to 8, or 6 or 7 metals.
  • the medium to high entropy alloy may have a composition including a plurality of metals selected from alkali metals, alkaline earth metals, lanthanoids, actinoids, transition metals, post- transition metal, oxides thereof, a carbide thereof, a nitride thereof, or a combination of two or more thereof.
  • the medium to high entropy alloy may comprise one or more (e.g., at least two, at least three, or at least four) of the metals selected from the same group of earth metals, lanthanoids, actinoids, transition metals, post-transition metals, an oxide thereof, a carbide thereof, a nitride thereof, or a combination of two or more thereof.
  • the medium to high entropy alloy may comprise two or more of the metals selected from a different group of earth metals, lanthanoids, actinoids, transition metals, post-transition metals, oxides thereof, or a mixture of two or more thereof.
  • the composition of the medium to high entropy alloy may include one or more metal selected from Li, Na, K, Rb, Cs, Fr, an oxide thereof, a carbide thereof, a nitride thereof, and a combination of two or more thereof.
  • the medium to high entropy alloy includes at least one metal selected from Na, K, Rb, Cs, Fr, an oxide thereof, a carbide thereof, a nitride thereof, and a combination thereof.
  • the medium to high entropy alloy may include at least one metal selected from Be, Mg, Ca, Sr, Ba, Ra, an oxide thereof, a carbide thereof, a nitride thereof, and a combination thereof.
  • the medium to high entropy alloy includes at least one of Mg, Sr, Ba, Ra, an oxide thereof, a carbide thereof, a nitride thereof, or a combination thereof.
  • the composition of the medium to high entropy alloy may include a metal selected from Ln, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, an oxide thereof, a carbide thereof, a nitride thereof, and a combination of two or more thereof.
  • the composition of the medium to high entropy alloy may include one or more metals selected from Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, Lr, an oxide thereof, a carbide thereof, a nitride thereof, and a combination of two or more thereof.
  • the medium to high entropy alloy includes at least one metal selected from Ac, Th, Pa, Np, Am, Cm, Bk, Cf, Es, Fm, Md, No, Lr, an oxide thereof, a carbide thereof, a nitride thereof, and a combination of two or more thereof.
  • the composition of the medium to high entropy alloy may include one or more metals selected from Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, Ta, W, Re, Os, lr, Pt, Au, Hg, Rf, Db, Sg, Bh, Hs, Mt, Ds, Rg, Cn, an oxide thereof, a carbide thereof, a nitride thereof, and a combination of two or more thereof.
  • the medium to high entropy alloy may include at least one metal of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, Hf, W, Pt, Au, Hg, Rf, Mt, Ds, Rg, Cn, an oxide thereof, a carbide thereof, a nitride thereof, or a combination of two or more thereof.
  • the medium to high entropy alloy includes at least one metal selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Rh, Pd, Ag, Hf, W, Pt, Au, an oxide thereof, a carbide thereof, a nitride thereof, and a combination of two or more thereof.
  • the medium to high entropy alloy includes at least one metal of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Pd, Ag, W, Pt, Au, an oxide thereof, a carbide thereof, a nitride thereof, or a combination of two or more thereof.
  • the medium to high entropy alloy may include at least one metal selected from In, Al, Pb, Ga, Bi, TI, Sn, Po, an oxide thereof, a carbide thereof, a nitride thereof, and a combination of two or more thereof.
  • the medium to high entropy alloy may include at least one metal selected from In, Al, Pb, Ga, TI, Sn, an oxide thereof, a carbide thereof, a nitride thereof, and a combination of two or more thereof.
  • the medium to high entropy alloy includes at least one metal selected from Al, Pb, Sn, an oxide thereof, a carbide thereof, a nitride thereof, and a combination of two or more thereof.
  • the composition of the medium to high entropy alloy includes one or more metals selected from Co, Ni, Fe, Cr, Mn, Ti, V, Zn, Cu, Mg, Al, Mo, Ir, Nb, Ga, Ge, Sr, Y, Zr, Rh, Pd, Ag, Sn, Sb, Hf, Ta, Pt, Au, an oxide thereof, a carbide thereof, a nitride thereof, and a combination of two or more thereof.
  • the composition of the medium to high entropy alloy comprises 4 and 9 metals chosen from Cr, Fe, V, Al, Si, Mn, Mo, Ti, Ni, an oxide thereof, a carbide thereof, a nitride thereof, and a mixture of two or more thereof.
  • the medium to high entropy alloy comprises one or more metals selected from Co, Ni, Cu, Rh, Ir, Zr, an oxide thereof, a carbide thereof, a nitride thereof, and a combination of two or more thereof.
  • the medium to high entropy alloy includes one or more metals selected from Co, Ni, Fe, Cr, Mn, Ti, V, Zn, Cu, Mg, an oxide thereof, a carbide thereof, a nitride thereof, and a combination of two or more thereof.
  • the composition of the medium to high entropy alloy may comprise Cr, Mn, Co, Ni, Fe, an oxide thereof, a carbide thereof, a nitride thereof, or a combination of two or more thereof.
  • the medium to high entropy alloy may comprise Co, Cr, Fe, Mo, Nb, an oxide thereof, a carbide thereof, a nitride thereof, or a combination of two or more thereof.
  • the composition of the medium to high entropy alloy typically comprises a composition having a plurality of metals comprising four or more metals present in a mass fraction of about 0.05 or more.
  • the four or more metal present in a mass fraction of about 0.05 or more are sometimes referred to herein as principal metals.
  • the mass fraction of the four or more principal metals may be from about 0.05 to about 0.35.
  • At least one of the four or more principal metals may be present in a mass fraction amount from about 0.05 to about 0.35, about 0.05 to about 0.33, about 0.05 to about 0.31, about 0.05 to about 0.29, about 0.05 to about 0.27, about 0.05 to about 0.25, about 0.05 to about 0.23, about 0.05 to about 0.21, about 0.05 to about 0.19; from about 0.1 to about 0.35, about 0.1 to about 0.33, about 0.1 to about 0.31, about 0.1 to about 0.29, about 0.1 to about 0.27, about 0.1 to about 0.25, about 0.1 to about 0.23, about 0.1 to about 0.21, about 0.1 to about 0.19; from about 0.13 to about 0.35, about 0.13 to about 0.33, about 0.13 to about 0.31, about 0.13 to about 0.29, about 0.13 to about 0.27, about 0.13 to about 0.25, about 0.13 to about 0.23, about 0.13 to about 0.21, about 0.13 to about 0.19; from about 0.16 to about 0.35, about 0.16
  • the mass fraction of at least two of the four or more principal metal is from about 0.10 to about 0.35, optional from about 0.15 to about 0.3, or optionally from about 0.2 to about 0.3.
  • each of the four principal metals are present in the medium to high entropy alloy in a mass fraction of about 0.05 to about 0.35, including any of the ranges listed above with respect to at least one of the four or more principal metals.
  • the medium to high entropy alloys typically includes a micro structure comprising a metal phase, a metal oxide phase, or a combination thereof.
  • the micro structure may include a metal that is a BCC metal phase or an FCC metal phase.
  • the micro structure may comprise a plurality of phases selected from metal phases, metal oxide phases, or combinations thereof.
  • the microstructure may comprise two, three, four, five, six, seven, eight, nine, ten, or any range or subrange formed therefrom of phases.
  • the medium to high entropy alloy comprises from 2 to 9, 2 to 8, 2 to 7, 2 to 6, 2 to 5, 2 to 4; from 3 to 9, 3 to 8, 3 to 7, 3 to 6; from 4 to 9, 4 to 8, 4 to 7, 4 to 6, 4 or 5; from 5 to 9, 5 to 8, 5 to 7, 5 or 6; from 6 to 9, 6 to 8, or 6 or 7, of phases in the micro structure.
  • the medium to high entropy alloys may comprise one or more microstructures
  • the medium to high entropy alloy may comprise a single micro structure.
  • the components, particles, and/or phases of the microstructure may be uniformly or substantially uniformly dispersed throughout the medium to high entropy alloy.
  • substantially uniform dispersion and substantially uniformly dispersed refer to a component (e.g., metal and/or metal oxide) being dispersed within 10% of a uniform dispersion.
  • the uniformity of the microstructure may be measured using devices including, e.g., X-ray fluorescence (XRF) analyzers, scanning electron microscopes (SEM), and/or energy dispersive X-ray spectroscopy (EDS) apparatuses.
  • XRF X-ray fluorescence
  • SEM scanning electron microscopes
  • EDS energy dispersive X-ray spectroscopy
  • the medium to high entropy alloy may be configured to have a form, preferably adapted for the desired use and/or application.
  • the medium to high entropy alloy may be configured to have a form and/or shape that is geometric or substantially geometric (e.g., such as a square, rectangle, orthogonal, rhombus, trapezoid, spherical, or the like).
  • the medium to high entropy alloy is configured to have the form and/or shape of a pellet, a bar, a sheet, or the like.
  • the medium to high entropy alloys may comprise a first section comprising a first micro structure and optionally a first composition and a second section comprising a second microstructure and optionally a second composition.
  • the second microstructure when present, is different from the first microstructure.
  • the medium to high entropy alloy may include a first section having a first micro structure comprising a metal phase and a second section having a second microstructure comprising a metal oxide phase.
  • the first microstructure may have a larger volumetric fraction of an FCC and/or BCC metal phase than the second micro structure.
  • the first micro structure of the first section may have a total volume fraction of metal phase(s) that is larger than the total volume of metal phases of the second micro structure of the second section by about 7 % or more, about 14 % or more, about 21 % or more, about 28 % or more, about 35 % or more, about 45 % or more, about 55 % or more, about 75 % or more, about 100 % or more, about 140 % or more, or about 180 % or more.
  • the medium to high entropy alloy has a first section having a first microstructure and a second section having a second microstructure, where the first microstructure has a total volume fraction of metal phase(s) that is larger than the total volume of metal phases of the second microstructure by about 7 % to about 140%, about 7 % to about 100%, about 7 % to about 75 %, about 7 % to about 55 %, about 7 % to about 45 %, about 7 % to about 35 %, about 7 % to about 25 %, about 7 % to about 15 %; from about 17 % to about 140%, about 17 % to about 100%, about 17 % to about 75 %, about 17 % to about 55 %, about 17 % to about 45 %, about 17 % to about 35 %; from about 27 % to about 140%, about 27 % to about 100%, about 27 % to about 75 %, about 27 % to about 55 %, about 27 % to about 45 %; from about 47
  • the second micro structure phase may have a larger volumetric fraction of metal oxide phases than the first microstructure.
  • the second micro structure of the second section of the medium to high entropy alloy may have a total volume fraction of metal oxide(s) that is larger than the total volume fraction of metal oxide(s) of the first micro structure of the first section by about 7 % or more, about 14 % or more, about 21 % or more, about 28 % or more, about 35 % or more, about 45 % or more, about 55 % or more, about 75 % or more, about 100 % or more, about 140 % or more, or about 180 % or more.
  • the medium to high entropy alloy has a first section having a first micro structure and a second section having a second microstructure, where the second microstructure has a total volume fraction of metal oxide phase(s) that is larger than the total volume of metal oxide phases of the first micro structure by about 7 % to about 140%, about 7 % to about 100%, about 7 % to about 75 %, about 7 % to about 55 %, about 7 % to about 45 %, about 7 % to about 35 %, about 7 % to about 25 %, about 7 % to about 15 %; from about 17 % to about 140%, about 17 % to about 100%, about 17 % to about 75 %, about 17 % to about 55 %, about 17 % to about 45 %, about 17 % to about 35 %; from about 27 % to about 140%, about 27 % to about 100%, about 27 % to about 75 %, about 27 % to about 55 %, about 27 % to about 45 %; from about 27
  • the medium to high entropy alloy has a first section that is in the form of a first layer and a second section that is in the form of a second layer.
  • the medium to high entropy alloy may be configured to have a first section (e.g., a first layer) adapted for bonding, coupling, and/or attachment to a metal substrate and a second section (e.g., a second layer) adapted for bonding, coupling, and/or attachment to a ceramic substrate.
  • the medium to high entropy alloy may be configured to have a metal layer adapted for coupling to a metal substrate and a metal oxide layer adapted for coupling to ceramic substrate.
  • the medium to high entropy alloy may be configured to have a first section (e.g., a first layer) that has an electrical resistance that is different from the electrical resistance of a second section (e.g., a second layer) of the medium to high entropy alloy.
  • the medium to high entropy alloy has a first section that is in the form of a shell layer and a second section that is in the form of a core, wherein the first shell layer at least partially surrounds the core.
  • the shell layer may completely surround or encapsulate the core in some embodiments.
  • the medium to high entropy alloy may be configured such that the first section and/or the second section have an average thickness of about 100 to about 300 ⁇ m.
  • the average thickness of the first section, the second section, or both the first and the second section is about 100 to about 280 ⁇ m, 115 to about 280 ⁇ m, 115 to about 270 ⁇ m, about 130 to about 270 ⁇ m, about 130 to about 260 ⁇ m, about 160 to about 260 ⁇ m, about 160 to about 240 ⁇ m, about 170 to about 240 ⁇ m, about 170 to about 220 ⁇ m, or any range or subrange formed therefrom.
  • Examples A-F Six non-limiting example high entropy alloys (Examples A-F) were prepared in accordance with aspects of the invention.
  • Examples A-F were prepared from the following feed oxide powders: Co(OH)2 (99.9%), Cr2O3 (99.0%), Fe2O3 (99.998%), NiO (99.998%), and MnO2 (99.9%). While Co(OH)2 was used as the source of Co in this Example, it is contemplated that medium to high entropy alloys can be prepared using CoO. The powders were weighed and mixed together in the proportion, such that assuming complete reduction, the high entropy alloy composition would be an equimolar Cantor composition, CoCrFeNiMn.
  • the feed oxide powders were mixed together and ball milled for a minimum of 12 hours in 200 proof ethanol with alumina milling media to ensure homogeneous mixing of the component oxides. After milling, the mixture of feed oxide powders were sieved to remove the milling media, washed using ethanol, and subsequently dried under vacuum. The dried mixture of feed oxide powders was then compacted in steel dies to cylindrical pellets ( ⁇ 20 x 7 mm) by uniaxial pressing at 2500 psi.
  • Example A-F The pellets were embedded in graphite powder and subjected to isothermal reduction heat treatment at various temperatures ranging from 1000 °C to 1185 °C for different time periods from 24 to 120 hours in a flowing 3 mol.% H 2 balanced argon atmosphere to produce Examples A-F, which were in the form of a pellet.
  • the gas atmosphere used in this Example was forming gas (5 mol.% H 2 - N 2 ) to circumvent the possible formation of nitrides.
  • Table 1 A summary of the reduction heat treatments used in the production of Examples A-F is shown in Table 1.
  • Phase identification for the pellets of Examples A-F was carried out utilizing powder X- ray diffraction (XRD, Malvern Panalytical Empyrean, Bragg -Brentano geometry, Cu-K ⁇ source, 1.54184 A, 40 kV, 45 mA).
  • XRD powder X-ray diffraction
  • Each data set was calibrated with a NIST silicon standard where the X-ray diffraction (XRD) patterns of the silicon and the samples were collected at the same time under identical conditions.
  • the XRD patterns were acquired at high resolution, with a 29 step size of -0.01°. XRD patterns from the surfaces as well as the cores of the samples were collected.
  • the cores were exposed by grinding off the surface layers.
  • Cross-sections of the samples of Examples A-F were prepared for further characterizations using standard metallographic techniques.
  • the microstructures of the samples were characterized using scanning electron microscopy (SEM, Hitachi S-4300 FESEM, FEI Scios FIB). Elemental maps of selected regions of the samples were collected with the aid of Energy Dispersive X-ray Spectroscopy (EDS, FEI Scios FIB equipped with an EDAX-Ametek silicon drift detector). These results were complemented by electron microprobe analysis (JEOL JXA-8900) of regions of interest in the samples. The microprobe was operated at 15 kV accelerating voltage and 30 nA current to obtain accurate measurements of the samples.
  • FIG. 1A shows the microstructure (back-scattered electron contrast) of a sample of the pellet of Example A, which was heat-treated for 24 hours at a temperature of 1000 °C (3 mol.% H 2 -Ar).
  • the metallic regions exhibit bright contrast (due to their higher average atomic number) and are distributed throughout the sample. It can be seen that in some areas, coarsening has occurred, resulting in larger metallic grains.
  • Sample pellets of Examples D-F which had a higher reduction temperatures (e.g., 1150 or 1185 °C), developed a core-shell microstructure having a core comprising a mixture of oxide and metallic phases and a metallic outer shell layer.
  • the outer shell layer exhibited significantly less porosity than the core, and based on EDS compositional maps, was determined to be primarily metallic in nature.
  • the pellet of Example D which underwent reduction at a temperature of 1150 °C for 24 hours, had an outer shell layer that was discontinuous.
  • the pellet of Example E which underwent reduction at a temperature of 1185 °C for 24 hours, had an outer shell layer that was continuous.
  • the outer shell layer of the pellet of Example E had a thickness ranging from 11 pm to 147 ⁇ m as seen in FIG. IB).
  • the volume fraction of metallic phase is clearly much higher in the sample of the pellet of Example E than for the sample of the pellet of Example A, which was reduced at the temperature of 1000°C. Without being limited to any particular theory, it is believed that increasing the duration of annealing time to 120 hours, promoted the formation of a shell layer having a thickness that was more uniform and increased the thickness of the shell layer to about 194 pm.
  • FIG. 2 is an image of the X-ray EDS elemental maps of the sample of the pellet of Example F.
  • the X- ray EDS elemental map was of an area that encompassed both the core and shell layer regions of the sample of the pellet of Example F.
  • the dense outer shell layer of the sample of the pellet of Example F contains iron, cobalt, nickel, chromium and manganese, and is essentially devoid of oxygen.
  • the core of the sample of the pellet of Example F contained a mixture of oxide and metallic phases similar to the observations of Example E in FIG. IB. As seen most clearly in the coarsened regions, the metal is enriched in Fe, Co and Ni, and deficient in Cr and Mn. From the Mn map it is also apparent that the core of the sample of the pellet of Example F had a higher concentration of Mn rich oxide phases.
  • X-ray diffraction (XRD) spectra were obtained from both the near surface and interior of the samples of the pellets of Examples A-F. Three distinct phases were detected from the XRD spectra, namely an FCC phase, a manganese chromate (MnCr 2 O 4 ) phase, and a chromium (III) oxide (Cr 2 O 3 ) phase. The relative fraction of the different phases was estimated from the area of the XRD peaks, and the results are presented in Table 3 for the sample pellets that had undergone reduction for 24 hours at different temperatures.
  • XRD X-ray diffraction
  • the shell is formed, it is believed that the reduction of the interior regions can only take place if there is inward diffusion of hydrogen, and the outward transport of H 2 O; of these two processes, the latter is most likely the rate limiting due to steric considerations.
  • the shell formation thus results in a local increase in the pO 2 in the core region. Due to the resulting slowing of the reduction kinetics, there is increased time for the residual MnO and Cr 2 O 3 to react to form MnCr 2 CO 4 . Additionally, one of the factors that determines whether a core-shell structure develops is the relative kinetics of sintering of the metallic product versus oxide reduction.
  • the WDS results showed that the composition of the shell layer was fairly homogeneous at any given depth in the pellets.
  • the concentrations of Fe and Mn exhibited a slight compositional gradient through the thickness of the shell of the pellets. More specifically, the manganese concentration varied from 0.079 atom fraction at the surface to 0.085 atom fraction at a depth of about 100 ⁇ m, while the iron concentration varied from 0.254 at the surface to 0.250 atom fraction.
  • the average composition of the shell layer of the pellet samples of Example F was determined to be Co 0.25 Cr 0.19 Fe 0.25 Ni 0.23 Mn 0.08 .
  • the processed high entropy alloy of Example F was deficient in manganese, with corresponding excess of iron, cobalt and nickel.
  • the reduction of manganese oxides in the samples of the pellets of Examples A-F was further evaluated in view of the difficulty of reducing manganese oxides.
  • the reduction of manganese (IV) oxide (MnO 2 ) is a complex process, whereby a series of intermediate oxides is formed with progressively lower oxygen content: MnO 2 ⁇ Mn 2 O 3 ⁇ Mn 3 O 4 ⁇ MnO ⁇ Mn. Whereas reduction from MnO 2 to MnO can be achieved relatively easily at pO 2 values of approximately 10 -4 , MnO is very stable.
  • the comparative sample prepared from the MnO 2 powder contained a MnO phase. Moreover, for the comparative sample, no other phases were identified in the powder x-ray diffraction measurements. Thus, the MnO 2 powder was only reduced to MnO for the comparative sample.
  • the example high entropy alloy developed a core-shell structure with a metallic shell containing a phase of Mn. This result strongly suggests that there is a synergistic effect that promotes the reduction of MnO to its metallic state for the example high entropy alloy prepared according to the methods described in this Example and Example 1.

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Abstract

L'invention concerne des alliages à entropie moyenne à élevée et des procédés de production de ceux-ci. Selon un premier aspect, l'invention concerne un procédé de production d'un alliage à entropie moyenne à élevée. Le procédé peut consister à mélanger une composition d'alimentation pour obtenir un mélange d'oxyde métallique, la composition d'alimentation comprenant quatre oxydes métalliques ou plus choisis parmi les oxydes de métaux alcalins, des oxydes de métaux alcalino-terreux, des oxydes de lanthanides, des oxydes d'actinides, des oxydes de métaux de transition, des oxydes de métaux de post-transition, ou une combinaison de deux ou plus de ces oxydes ; et à réduire le mélange d'oxydes métalliques pour produire un alliage à entropie moyenne à élevée.
PCT/US2022/050295 2021-11-18 2022-11-17 Alliages à entropie moyenne à élevée et leurs procédés de fabrication WO2023091595A1 (fr)

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CN116855113A (zh) * 2023-07-06 2023-10-10 中国科学院合肥物质科学研究院 一种高熵复合氧化物阻氢涂层及制备方法

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US5348592A (en) * 1993-02-01 1994-09-20 Air Products And Chemicals, Inc. Method of producing nitrogen-hydrogen atmospheres for metals processing
US20170209908A1 (en) * 2016-01-27 2017-07-27 David B. Smathers Fabrication of high-entropy alloy wire and multi-principal element alloy wire
WO2020142125A2 (fr) * 2018-10-09 2020-07-09 Oerlikon Metco (Us) Inc. Oxydes à entropie élevée pour revêtements supérieurs de revêtement de barrière thermique (tbc)
US20200392613A1 (en) * 2017-12-11 2020-12-17 Korea Institute Of Machinery & Materials High-entropy alloy, and method for producing the same

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US5348592A (en) * 1993-02-01 1994-09-20 Air Products And Chemicals, Inc. Method of producing nitrogen-hydrogen atmospheres for metals processing
US20170209908A1 (en) * 2016-01-27 2017-07-27 David B. Smathers Fabrication of high-entropy alloy wire and multi-principal element alloy wire
US20200392613A1 (en) * 2017-12-11 2020-12-17 Korea Institute Of Machinery & Materials High-entropy alloy, and method for producing the same
WO2020142125A2 (fr) * 2018-10-09 2020-07-09 Oerlikon Metco (Us) Inc. Oxydes à entropie élevée pour revêtements supérieurs de revêtement de barrière thermique (tbc)

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CN116855113B (zh) * 2023-07-06 2024-05-31 中国科学院合肥物质科学研究院 一种高熵复合氧化物阻氢涂层及制备方法

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