Medium to high entropy alloys and methods of making the same

Abstract

Medium to high entropy alloys and methods for producing the same are disclosed herein. In accordance with a first aspect, provided is a method for producing a medium to high entropy alloy. The method may comprise 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 carth 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.

1 . A method for producing a medium to high entropy alloy, the method 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;   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.   
     
     
         2 . The method according to  claim 1 , wherein the feed composition comprises four or more metal oxides 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. 
     
     
         3 . (canceled) 
     
     
         4 . The method according to laim  1  further comprising:
 milling the metal oxide mixture prior to heat treatment for about 1 to about 30 hours. 
 
     
     
         5 . The method according to  claim 1 , wherein the temperature is about 900 to about 1,500° C. and the annealing time is about 20 to about 180hours. 
     
     
         6 . (canceled) 
     
     
         7 . The method according to  claim 1 , wherein the atmosphere for the heat treatment is non-flammable and comprises of about 1 to 4.5 mol. % of hydrogen and about 95.5 mol. % or more of argon, nitrogen, or a combination thereof. 
     
     
         8 . The method according to  claim 1 , wherein the temperature is about 1200° C. or less, and the medium to high entropy alloy comprises a microstructure having about 2 mol. % to about 16 mol. % of a Mn metal phase. 
     
     
         9 . The method according to  claim 1  further comprising:
 forming a pellet from the metal oxide mixture prior to the heat treatment. 
 
     
     
         10 . The method according to  any foregoing claim 1 , wherein the medium to high entropy alloy has a microstructure comprising a metal phase, a metal oxide phase, or a combination thereof. 
     
     
         11 - 14 . (canceled) 
     
     
         15 . A medium to high entropy alloy comprising:
 a composition comprising a plurality of metals comprising four or more metals present in a mass fraction of about 0.05 or more; and   a microstructure comprising a metal phase, a metal oxide phase, or a combination thereof.   
     
     
         16 . The medium to high entropy alloy of  claim 15 , wherein the mass fraction of each of the four or more metals is from about 0.05 to about 0.35. 
     
     
         17 . (canceled) 
     
     
         18 . The medium to high entropy alloy according to  claim 15 , wherein the medium to high entropy alloy has a first section comprising a first microstructure and a second section comprising a second microstructure, the second microstructure being different than the first microstructure. 
     
     
         19 . The medium to high entropy alloy according to  claim 18 , wherein the first microstructure has a larger volumetric fraction of a FCC metal phase than the second microstructure and wherein the second microstructure phase has a large volumetric fraction of metal oxide phases than the first microstructure. 
     
     
         20 . (canceled) 
     
     
         21 . (canceled) 
     
     
         22 . The medium to high entropy alloy according to  claim 18 , wherein the first section is a shell layer and the second section is a core, wherein the first shell layer at least partially surrounds the core. 
     
     
         23 . The medium to high entropy alloy according to  claim 18 , wherein the medium to high entropy alloy comprises metal oxide layer and metal layer. 
     
     
         24 . (canceled) 
     
     
         25 . (canceled) 
     
     
         26 . The medium to high entropy alloy according to  claim 1 , wherein the first section has an average thickness of about 100 to about 300 μm. 
     
     
         27 . The medium to high entropy alloy according to  claim 15 , wherein the microstructure comprises a FCC metal phase having a lattice parameter of about 3.3 to about 3.9 Å. 
     
     
         28 . (canceled) 
     
     
         29 . (canceled) 
     
     
         30 . A method for producing a medium to high entropy alloy, the method 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.   
     
     
         31 . (canceled) 
     
     
         32 . The method according to  claim 30 , wherein the metal oxide mixture is completely reduced. 
     
     
         33 . The method according to  claim 30 , wherein the metal oxide mixture comprises a manganese oxide, wherein the metal oxide mixture is reduced by annealing at an annealing temperature that less than the melting temperature of the manganese oxide. 
     
     
         34 - 36 . (canceled) 
     
     
         37 . The method according to  claim 30 , wherein the metal oxide mixture comprises a chromium oxide, wherein the metal oxide mixture is reduced by annealing at an annealing temperature that less than the melting temperature of the chromium oxide.