Degassing of nano-phase separating powders in a hydrogen containing atmosphere

Abstract

Removal of gas-evolving species from powders can be achieved before sintering occurs, reducing or eliminating gas evolution in a dense body that can lead to swelling, or lowering of density.

1 . A method of reducing gas production during metal alloy powder sintering comprising:
 providing a mechanically alloyed metal alloy powder;   annealing the metal alloy powder at an annealing temperature below a sintering temperature, the annealing of the metal alloy powder being in an atmosphere including hydrogen or the metal alloy powder including an oxygen getter, or both; and   sintering the metal alloy powder at a sintering temperature to reduced gas production during the sintering.   
     
     
         2 . The method of  claim 1 , further comprising pressing the annealed metal alloy powder to form a green body prior to sintering. 
     
     
         3 . The method of  claim 1 , further comprising pressing the annealed metal alloy powder to form a green body prior to annealing. 
     
     
         4 . The method of  claim 1 , wherein the metal alloy powder is a nano-phase separating powder. 
     
     
         5 . The method of  claim 1 , wherein the metal alloy powder includes an additive. 
     
     
         6 . The method of  claim 5 , wherein the additive includes an organic material. 
     
     
         7 . The method of  claim 1 , wherein the metal alloy powder includes nickel. 
     
     
         8 . The method of  claim 1 , wherein the metal alloy powder includes chromium. 
     
     
         9 . The method of  claim 1 , wherein the metal alloy powder includes iron. 
     
     
         10 . The method of  claim 1 , wherein the metal alloy powder includes copper. 
     
     
         11 . The method of  claim 1 , wherein the metal alloy powder includes vanadium. 
     
     
         12 . The method of  claim 1 , wherein the metal alloy powder includes molybdenum. 
     
     
         13 . The method of  claim 1 , wherein the metal alloy powder includes tungsten. 
     
     
         14 . The method of  claim 1 , wherein the metal alloy powder includes silver. 
     
     
         15 . The method of  claim 1 , wherein the metal alloy powder includes zirconium. 
     
     
         16 . The method of  claim 1 , wherein the metal alloy powder includes a ternary nano-phase separating powder. 
     
     
         17 . The method of  claim 1 , wherein the oxygen getter includes an alloying element having a strong preference to form an oxide. 
     
     
         18 . The method of  claim 17 , wherein the oxygen getter includes zirconium, chromium, vanadium, manganese or combinations thereof. 
     
     
         19 - 22 . (canceled) 
     
     
         23 . A metal alloy powder for sintering comprising:
 a mechanically alloyed powder having a reduced amount of gas-evolving species compared to the amount of gas-evolving species in the mechanically alloyed powder prior to annealing in a hydrogen atmosphere.   
     
     
         24 - 28 . (canceled) 
     
     
         29 . A method of forming a sintered alloy, comprising:
 annealing a nano-phase separating metal alloy powder in the presence of hydrogen; and   sintering the nano-phase separating metal alloy powder to form a sintered alloy product including nickel and having a relative density of at least 80%.   
     
     
         30 - 32 . (canceled)