Method for making tungsten-refactory metal alloy powder and tungsten-refractory metal alloy powders made by the method

Abstract

A method for forming tungsten-refractory metal alloy powders, and tungsten-refractory metal alloy powders formed by the method. The method includes mixing a majority portion by weight of a base tungsten powder with a minority portion by weight of a base refractory metal powder to form a mixture, which is then milled for a period of time sufficient to at least partially mechanically alloy the base tungsten powder and base refractory metal powder together to form at-least-partially-mechanically-alloyed particles, which are then heat treated to a temperature sufficient to promote diffusion between tungsten and the refractory metal and obtain agglomerations of particles having only a tungsten phase, which are then milled to break up the agglomerations of particles and obtain the tungsten-refractory metal alloy powder.

1 - 29 . (canceled) 
     
     
         30 . A method for forming a tungsten-refractory metal alloy powder, the method comprising the steps of:
 (a) mixing a majority portion by weight of a base tungsten powder with a minority portion by weight of a base refractory metal powder to form a mixture, said base refractory metal powder being formed of a refractory metal other than tungsten;   (b) milling the mixture from step (a) for a period of time sufficient to at least partially mechanically alloy the base tungsten powder and base refractory metal powder together to form at-least-partially-mechanically-alloyed particles;   (c) heat treating the at-least-partially-mechanically-alloyed particles from step (b) to a temperature sufficient to promote diffusion between tungsten and the refractory metal other than tungsten and obtain agglomerations of particles having only a tungsten phase; and   (d) milling the agglomerations of particles having only a tungsten phase from step (c) to break up the agglomerations of particles and obtain the tungsten-refractory metal alloy powder.   
     
     
         31 . The method according to  claim 30 , wherein the base refractory metal powder in step (a) is rhenium powder, and wherein the rhenium powder in step (a) comprises from about 20% to about 25.75% of the mixture by weight. 
     
     
         32 . The method according to  claim 31 , further comprising adding hafnium carbide powder to the mixture in step (a), and wherein the amount of the hafnium carbide powder added to the mixture in step (a) is such that the hafnium carbide powder comprises up to 4% of the mixture by weight. 
     
     
         33 . The method according to  claim 30 , wherein the base refractory metal powder in step (a) is molybdenum powder, and wherein the molybdenum powder in step (a) comprises from about 20% to about 40% of the mixture by weight. 
     
     
         34 . The method according to  claim 33 , further comprising adding zirconium oxide powder to the mixture in step (a), and wherein the amount of zirconium oxide powder added to the mixture in step (a) is such that the zirconium oxide powder comprises up to 2% of the mixture by weight. 
     
     
         35 . The method according to  claim 30 , wherein the milling in step (b) is performed using a planetary ball mill that uses stainless steel jars and stainless steel and/or tungsten carbide balls as milling media. 
     
     
         36 . The method according to  claim 30 , wherein the period of time in step (b) is less than 24 hours. 
     
     
         37 . The method according to  claim 30 , wherein the period of time in step (b) is less than 8 hours. 
     
     
         38 . The method according to  claim 30 , wherein the at-least-partially-mechanically-alloyed particles have an average particle size (D 50 ) of less than about 20 microns after step (b). 
     
     
         39 . The method according to  claim 30 , wherein the at-least-partially-mechanically-alloyed particles from step (b) are heated at a temperature of from about 1,000° C. to about 1,700° C. for about 1 hour to about 12 hours in step (c). 
     
     
         40 . The method according to  claim 30 , wherein the milling in step (d) is performed using a planetary ball mill that uses stainless steel jars and stainless steel and/or tungsten carbide balls as milling media. 
     
     
         41 . The method according to  claim 30 , wherein the milling in step (d) is performed for a period of time less than 24 hours. 
     
     
         42 . The method according to  claim 30 , wherein the milling in step (d) is performed for a period of time less than 8 hours. 
     
     
         43 . The method according to  claim 30 , wherein the tungsten-refractory metal alloy powder has an average particle size (D 50 ) of less than about 20 microns after step (d). 
     
     
         44 . The method according to  claim 30 , wherein:
 (i) the base refractory metal powder in step (a) is rhenium powder;   (ii) the rhenium powder in step (a) comprises from about 25±1% of the mixture by weight;   (iii) the period of time in step (b) is less than 8 hours;   (iv) the at-least-partially-mechanically-alloyed particles have an average particle size (D 50 ) of less than about 20 microns after step (b);   (v) the at-least-partially-mechanically-alloyed particles from step (b) are heated at a temperature of from about 1,600° C. to about 1,700° C. for about 1 hour to about 12 hours in step (c);   (vi) the milling in step (d) is performed for a period of time less than 8 hours; and   (vii) the tungsten-refractory metal alloy powder has an average particle size (D 50 ) of less than about 16 microns after step (d).   
     
     
         45 . The method according to  claim 44 , further comprising adding hafnium carbide powder to the mixture in step (a) such that the hafnium carbide powder comprises up to 2% of the mixture by weight. 
     
     
         46 . The method according to  claim 30 , wherein:
 (i) the base refractory metal powder in step (a) is molybdenum powder;   (ii) the molybdenum powder in step (a) comprises from about 30±1% of the mixture by weight;   (iii) the period of time in step (b) is less than 8 hours;   (iv) the at-least-partially-mechanically-alloyed particles from step (b) have an average particle size (D 50 ) of less than about 20 microns after step (b);   (v) the at-least-partially-mechanically-alloyed particles from step (b) are heated at a temperature of from about 1,600° C. to about 1,700° C. for about 1 hour to about 12 hours in step (c);   (vi) the milling in step (d) is performed for a period of time less than 8 hours; and   (vii) the tungsten-refractory metal alloy powder has an average particle size (D 50 ) of less than about 16 microns after step (d).   
     
     
         47 . The method according to  claim 46 , further comprising adding zirconium oxide powder to the mixture in step (a) such that the zirconium oxide powder comprises up to 2% of the mixture by weigh. 
     
     
         48 . The method according to  claim 30 , further comprising forming spherical particles comprising the tungsten-refractory metal alloy powder obtained after step (d) by spray freeze drying. 
     
     
         49 . A tungsten-refractory metal alloy powder formed according to the method of  claim 30 .