Methods for forming polycrystalline materials including providing material with superabrasive grains prior to HPHT processing

A method of forming a polycrystalline compact, comprising:

• mixing grains of superabrasive material with particles of a material that exhibits a negative thermal expansion coefficient over at least a range of temperatures between room temperature and about 1000° C.;
• depositing at least two layers of material on the grains of superabrasive material in a chemical vapor infiltration process, the at least two layers having differing compositions, a first layer of the at least two layers of material comprising a carbon based material, a second layer of the at least two layers of material comprising at least one of cobalt, iron, and nickel;
• infiltrating the grains of superabrasive material having the at least two layers of material deposited thereon and the particles with a molten metal alloy at a temperature of about 1200° C. or less and cooling and solidifying the molten metal alloy within interstitial spaces between the grains of superabrasive material and the particles to form a solid metal alloy having the grains of superabrasive material and the particles embedded therein, wherein infiltrating the grains of superabrasive material and the particles with the molten metal alloy comprises infiltrating the grains of superabrasive material and the particles at atmospheric pressure;
• and
• after forming the solid metal alloy, subjecting the solid metal alloy having the grains of superabrasive material and the particles embedded therein to a high pressure and high temperature process and forming inter-granular bonds between the grains of superabrasive material.

A method of forming a cutting element comprising a polycrystalline compact, comprising:

• depositing material on surfaces of grains of superabrasive material in a chemical vapor infiltration process and forming a three-dimensional solid porous body comprising the grains of superabrasive material bonded to one another by the material deposited on the surfaces of the grains of superabrasive material, wherein the grains of superabrasive material are free of inter-granular bonds directly between the grains of superabrasive material;
• disposing loose grains of superabrasive material over a substrate;
• disposing the three-dimensional solid porous body over the loose grains of superabrasive material such that the loose grains of superabrasive material are disposed between the three-dimensional solid porous body and the substrate;
• and
• subjecting the three-dimensional solid porous body, the loose grains of superabrasive material, and the substrate to a high pressure and high temperature process to form inter-granular bonds between the grains of superabrasive material.

A method of forming a cutting element comprising a polycrystalline compact for an earth-boring tool, comprising:

• depositing material on surfaces of grains of superabrasive material in a chemical vapor infiltration process and forming a three-dimensional solid porous body comprising the grains of superabrasive material bonded to one another by the material deposited on the surfaces of the grains of superabrasive material, wherein the grains of superabrasive material are free of inter-granular bonds directly between the grains of superabrasive material;
• infiltrating the three-dimensional solid porous body with a molten metal alloy at a temperature of about 1200° C. or less and solidifying the molten metal alloy to provide a first metal alloy within pores of the three-dimensional solid porous body;
• removing at least a portion of the first metal alloy from the pores of the three-dimensional solid porous body;
• disposing loose grains of superabrasive material over a substrate;
• disposing the three-dimensional solid porous body over the loose grains of superabrasive material such that the loose grains of superabrasive material are disposed between the three-dimensional solid porous body and the substrate;
• and
• subjecting the three-dimensional solid porous body, the loose grains of superabrasive material, and the substrate to a high pressure and high temperature process to form inter-granular bonds between the grains of superabrasive material after removing the at least a portion of the first metal alloy from the pores of the three-dimensional solid porous body, subjecting the three-dimensional solid porous body to a high pressure and high temperature process comprising providing a second metal alloy within interstitial spaces between inter-bonded grains of superabrasive material.