Polycrystalline diamond, methods of forming same, cutting elements, and earth-boring tools

Abstract

A method of forming polycrystalline diamond includes providing an alloy over at least portions of a plurality of diamond particles, and subjecting the plurality of diamond particles to a high-temperature, high-pressure process to form a polycrystalline diamond material having inter-granular bonds between adjacent diamond particles. The alloy includes iridium and nickel, and a volume of the diamond particles is at least about 92% of a total volume of the alloy and the diamond particles. The polycrystalline diamond material includes at least about 92% diamond by volume. A polycrystalline diamond compact includes grains of diamond bonded to one another by inter-granular bonds and an alloy disposed within interstitial spaces between the grains of diamond. The grains of diamond occupy at least 94% by volume of the polycrystalline diamond compact. An earth-boring tool may include a bit body and such a polycrystalline diamond compact.

What is claimed is: 
     
         1 . A method of forming polycrystalline diamond, comprising:
 providing an alloy over at least portions of a plurality of diamond particles, wherein the alloy comprises iridium and nickel, and wherein a volume of the diamond particles is at least about 92% of a total volume of the alloy and the diamond particles; and   subjecting the plurality of diamond particles to a high-temperature, high-pressure process to form a polycrystalline diamond material having inter-granular bonds between adjacent diamond particles, wherein the polycrystalline diamond material comprises at least about 92% diamond by volume.   
     
     
         2 . The method of  claim 1 , wherein providing an alloy over at least portions of a plurality of diamond particles comprises covering at least 30% of a surface area of the diamond particles with the alloy. 
     
     
         3 . The method of  claim 1 , wherein providing an alloy over at least portions of a plurality of diamond particles comprises forming a layer of the alloy having a thickness from about 1 nm to about 50 nm over the diamond particles. 
     
     
         4 . The method of  claim 1 , wherein providing an alloy over at least portions of a plurality of diamond particles comprises providing the alloy comprising about 5 mol % iridium to about 40 mol % iridium. 
     
     
         5 . The method of  claim 4 , wherein providing an alloy over at least portions of a plurality of diamond particles comprises providing the alloy comprising about 10 mol % iridium to about 35 mol % iridium. 
     
     
         6 . The method of  claim 1 , wherein providing an alloy over at least portions of a plurality of diamond particles comprises formulating the alloy to consist essentially of iridium and nickel. 
     
     
         7 . The method of  claim 1 , wherein providing an alloy over at least portions of a plurality of diamond particles comprises formulating the alloy to exhibit a liquidus of less than about 1,600° C. at atmospheric pressure. 
     
     
         8 . The method of  claim 1 , wherein providing an alloy over at least portions of a plurality of diamond particles comprises providing the alloy over a plurality of diamond particles having a multi-modal particle size distribution. 
     
     
         9 . The method of  claim 1 , wherein providing an alloy over at least portions of a plurality of diamond particles comprises providing the alloy over a plurality of diamond nanoparticles. 
     
     
         10 . The method of  claim 1 , wherein subjecting the plurality of diamond particles to a high-temperature, high-pressure process comprises subjecting the plurality of diamond particles to a temperature of at least about 1,400° C. and a pressure of at least about 5.0 GPa. 
     
     
         11 . The method of  claim 1 , wherein subjecting the plurality of diamond particles to a high-temperature, high-pressure process comprises subjecting the plurality of diamond particles to a pressure between about 6.5 GPa and 10 GPa. 
     
     
         12 . The method of  claim 1 , wherein providing an alloy over at least portions of a plurality of diamond particles comprises providing an alloy over at least portions of a plurality of diamond particles by a physical vapor deposition process. 
     
     
         13 . The method of  claim 1 , wherein subjecting the plurality of diamond particles to a high-temperature, high-pressure process comprises forming the polycrystalline diamond material defining at least one void without leaching the alloy therefrom. 
     
     
         14 . A polycrystalline diamond compact, comprising:
 a plurality of grains of diamond bonded to one another by inter-granular bonds, wherein the grains of diamond occupy at least 92% by volume of the polycrystalline diamond compact; and   an alloy disposed within interstitial spaces between the grains of diamond, the alloy comprising iridium and nickel, wherein the alloy comprises from about 1 mol % iridium to about 99 mol % iridium.   
     
     
         15 . The polycrystalline diamond compact of  claim 14 , wherein the alloy exhibits a liquidus of less than about 1,600° C. at atmospheric pressure. 
     
     
         16 . The polycrystalline diamond compact of  claim 14 , wherein the alloy is substantially free of iron and cobalt. 
     
     
         17 . The polycrystalline diamond compact of  claim 14 , wherein the alloy occupies from about 10% to about 90% of a total volume of the interstitial spaces. 
     
     
         18 . The polycrystalline diamond compact of  claim 14 , wherein the alloy further comprises carbon. 
     
     
         19 . The polycrystalline diamond compact of  claim 14 , wherein the polycrystalline diamond compact is unleached. 
     
     
         20 . An earth-boring tool comprising:
 a bit body; and   the polycrystalline diamond compact of  claim 14 .