Molybdenum-containing alloys and associated systems and methods

Abstract

Molybdenum-containing alloys, and associated systems and methods, are generally described. In certain embodiments, secondary and/or tertiary elements can be included, along with molybdenum, to provide beneficial properties during the sintering of the molybdenum-containing alloy. The molybdenum-containing alloys are, according to certain embodiments, nanocrystalline. According to certain embodiments, the molybdenum-containing alloys have high relative densities. The molybdenum-containing alloys can be relatively stable, according to certain embodiments. Inventive methods for making molybdenum-containing alloys are also described herein.

1 - 43 . (canceled) 
     
     
         44 . A sintered metal alloy comprising:
 molybdenum (Mo) and chromium (Cr), wherein   Mo is the most abundant element by atomic percentage in the sintered metal alloy,   chromium (Cr) is present in an amount from 0.5 at. % to 40 at. % of the sintered metal alloy, and   the sintered metal alloy has a relative density of greater than 95%.   
     
     
         45 . The sintered metal alloy of  claim 44 , wherein:
 the Mo is present in an amount of at least about 55 at. % of the sintered metal alloy,   the amount of Cr is least about 7 at. % of the sintered metal alloy, and/or   the amount of Cr is less than or equal to 20 at. % of the sintered metal alloy.   
     
     
         46 . The sintered metal alloy of  claim 44 , further comprising an additional element selected from the group consisting of tungsten (W), palladium (Pd), tantalum (Ta), and combinations thereof,
 wherein the additional element is present in an amount from about 0.5 at. % to about 40 at. % of the sintered metal alloy.   
     
     
         47 . The sintered metal alloy of  claim 44 , wherein the sintered metal alloy has a relative density of greater than 98%. 
     
     
         48 . The sintered metal alloy of  claim 44 , wherein at least 50% of a volume of the sintered metal alloy is made up of grains having sizes greater than or equal to 1000 nm. 
     
     
         49 . The sintered metal alloy of  claim 44  comprising grains having a size of greater than or equal to 1000 nm. 
     
     
         50 . The sintered metal alloy of  claim 44  being at least substantially stable at a temperature of at least 700° C. 
     
     
         51 . The sintered metal alloy of  claim 44 , wherein grain boundaries of the sintered metal alloy are rich in Cr. 
     
     
         52 . The sintered metal alloy of  claim 44  having a structure including Mo-rich grains and Cr-rich precipitates. 
     
     
         53 . The sintered metal alloy of  claim 44  being a bulk metal alloy. 
     
     
         54 . A nuclear thermal propulsion system comprising the sintered metal alloy of  claim 44 . 
     
     
         55 . A nuclear reactor comprising the sintered metal alloy of  claim 44 . 
     
     
         56 . A metal alloy formed by:
 sintering a plurality of particles comprising chromium (Cr) and molybdenum (Mo), the particles comprising a supersaturated phase including the Cr dissolved in the Mo in an amount that exceeds a solubility limit,   wherein the metal alloy includes the Cr and Mo and has a relative density of greater than 98%.   
     
     
         57 . The metal alloy of  claim 56 , wherein at least 50% of a volume of the metal alloy is made up of grains having sizes greater than or equal to 1000 nm. 
     
     
         58 . The metal alloy of  claim 56  being at least substantially stable at a temperature of at least 700° C. 
     
     
         59 . The metal alloy of  claim 56 , wherein:
 the Mo is present in the metal alloy in an amount of at least about 55 at. %,   the Cr is present in the metal alloy in an amount of at least about 7 at. %, and/or   the Cr is present in the metal alloy in an amount less than or equal to 20 at. %.   
     
     
         60 . The metal alloy of  claim 56 , further comprising an additional element selected from the group consisting of tungsten (W), palladium (Pd), tantalum (Ta), and combinations thereof,
 wherein the additional element is present in an amount from about 0.5 at. % to about 40 at. % of the metal alloy.   
     
     
         61 . A metal alloy powder for sintering, the metal alloy powder comprising:
 particles comprising a supersaturated phase including molybdenum (Mo) and a second element, the supersaturated phase including the second element dissolved in the Mo in an amount that exceeds a solubility limit,   wherein the Mo is the most abundant element by atomic percentage in the metal alloy powder, and   wherein the second element is present in the metal alloy powder in an amount from 0.5 at. % to 40 at. %.   
     
     
         62 . The metal alloy powder of  claim 61 , wherein the second element comprises chromium (Cr). 
     
     
         63 . The metal alloy powder of  claim 62 , wherein:
 an amount of the Mo in the metal alloy powder is at least about 55 at. %,   the amount of Cr in the metal alloy powder is at least about 7 at. %, and/or   the amount of Cr in the metal alloy powder is less than or equal to 20 at. %.   
     
     
         64 . The metal alloy powder of  claim 61 , further comprising a third element different from the second element, the third element being present in the metal alloy powder in an amount from 0.5 at. % to 40 at. %. 
     
     
         65 . The metal alloy powder of  claim 64 , wherein the third element is selected from the group consisting of tantalum (Ta), palladium (Pd), tungsten (W), and combinations thereof. 
     
     
         66 . The metal alloy powder of  claim 61 , wherein at least 50% of the particles are polycrystalline. 
     
     
         67 . The metal alloy powder of  claim 61 , wherein at least 50 volume percent of the particles have maximum cross-sectional dimensions from 1 micron to 1 millimeter. 
     
     
         68 . The metal alloy powder of  claim 61  being formed by mechanical alloying. 
     
     
         69 . A metal alloy powder for sintering, the metal alloy powder comprising:
 particles comprising a supersaturated phase including molybdenum (Mo) and chromium (Cr), the supersaturated phase including the Cr dissolved in the Mo in an amount that exceeds a solubility limit,   wherein the Mo is the most abundant element by atomic percentage in the metal alloy powder, and   wherein at least 50 volume percent of the particles have maximum cross-sectional dimensions from 1 micron to 1 millimeter.   
     
     
         70 . The metal alloy powder of  claim 69 , wherein the Cr is present in the metal alloy powder in an amount from about 0.5 at. % to about 40 at. %. 
     
     
         71 . The metal alloy powder of  claim 69 , wherein:
 an amount of the Mo in the metal alloy powder is at least about 55 at. %,   an amount of Cr in the metal alloy powder is at least about 7 at. %, and/or   an amount of Cr in the metal alloy powder is less than or equal to 20 at. %.   
     
     
         72 . The metal alloy powder of  claim 69 , further comprising a third element present in the metal alloy powder in an amount from 0.5 at. % to 40 at. %. 
     
     
         73 . The metal alloy powder of  claim 69 , wherein at least 50% of the particles are polycrystalline.