Cemented carbide - metallic alloy composites

Abstract

A method of making a composite sintered powder metal article includes providing a first powder comprising hard particles and a powdered binder in a first region of a mold. Providing a second powder comprising a metal or metal alloy powder in a second region of the mold, wherein the second powder contacts the first powder and comprises at least one of a metal powder and a metallic alloy powder. The first powder and the second powder are consolidated in the mold to provide a green compact. The green compact is sintered to provide a composite sintered powder metal article comprising a cemented hard particle region formed from the first powder and metallurgically bonded to a metallic second region formed from the second powder.

1 . A method of making a composite sintered powder metal article, comprising:
 providing a first powder in a first region of a mold, the first powder comprising hard particles and a powdered binder;   providing a second powder in a second region of the mold, wherein the second powder contacts the first powder and comprises at least one of a metal powder and a metallic alloy powder selected from a steel powder, a nickel powder, a nickel alloy powder, a molybdenum powder, a molybdenum alloy powder, a titanium powder, a titanium alloy powder, a cobalt powder, a cobalt alloy powder, a tungsten powder, and a tungsten alloy powder;   consolidating the first powder and the second powder in the mold to provide a green compact; and   sintering the green compact to provide a composite sintered powder metal article comprising a cemented hard particle region formed from the first powder and metallurgically bonded to a metallic second region formed from the second powder.   
     
     
         2 . The method of  claim 1 , wherein a thermal conductivity of the metallic second region is less than a thermal conductivity of the cemented hard particle region. 
     
     
         3 . The method of  claim 2 , wherein a thermal conductivity of the metallic second region is less than 100 W/mK. 
     
     
         4 . The method of  claim 1 , wherein a melting point of the metallic second region is greater than 1200° C. 
     
     
         5 . The method of  claim 1 , wherein the metallic second region comprises up to 50 percent by volume of one or more hard particles selected from the group consisting of a carbide, a nitride, a boride, a silicide, an oxide, and solid solutions thereof. 
     
     
         6 . The method of  claim 1 , wherein the metallic second region comprises up to 50 percent by volume of tungsten carbide particles. 
     
     
         7 . The method of  claim 1 , wherein the cemented hard particle region comprises hard particles dispersed in a continuous binder phase. 
     
     
         8 . The method of  claim 7 , wherein the hard particles comprise one or more hard particles selected from a carbide, a nitride, a boride, a silicide, an oxide, and solid solutions thereof, and the binder phase comprises at least one of cobalt, a cobalt alloy, molybdenum, a molybdenum alloy, nickel, a nickel alloy, iron, and an iron alloy. 
     
     
         9 . The method of  claim 7 , wherein the hard particles comprise carbide particles of at least one transition metal selected from titanium, chromium, vanadium, zirconium, hafnium, tantalum, molybdenum, niobium, and tungsten. 
     
     
         10 . The method of  claim 1 , wherein the cemented hard particle region comprises tungsten carbide particles. 
     
     
         11 . The method of  claim 10 , wherein the tungsten carbide particles have an average grain size of 0.3 to 10 μm. 
     
     
         12 . The method of  claim 7 , wherein the binder phase comprises cobalt. 
     
     
         13 . The method of  claim 1 , wherein the cemented hard particle region comprises from 2 to 40 volume percent of a continuous binder phase and from 60 to 98 volume percent of hard particles dispersed in the continuous binder phase. 
     
     
         14 . The method of  claim 1 , wherein the cemented hard particle region comprises particles of a hybrid cemented carbide. 
     
     
         15 . The method of  claim 14 , wherein the hybrid cemented carbide particles comprise:
 a cemented carbide continuous phase; and   a cemented carbide dispersed phase dispersed in the cemented carbide continuous phase;   
       wherein the contiguity ratio of the cemented carbide dispersed phase in the hybrid cemented carbide particles is less than or equal to 0.48. 
     
     
         16 . The method of  claim 15 , wherein the volume fraction of the cemented carbide dispersed phase in the hybrid cemented carbide particles is less than 50 volume percent and a contiguity ratio of the cemented carbide dispersed phase in the hybrid cemented carbide particles is less than or equal to 1.5 times the volume fraction of the dispersed phase in the hybrid cemented carbide particles. 
     
     
         17 . The method of  claim 1 , wherein metallic second region has a thickness of at least 100 microns.