Patent ID: 8261632

Claim:
A method of forming an earth-boring rotary drill bit, the method comprising: providing a first powder mixture comprising a plurality of hard particles and a plurality of particles comprising a matrix material within a region of a container configured to form a bit body; providing a second powder mixture comprising a plurality of hard particles and a plurality of particles comprising a matrix material exhibiting a different material composition than a material composition of the first powder mixture within another region of the container configured to form a pin; pressing the first and second powder mixtures within the container to form a green unitary structure; machining a tapered surface into a portion of the green unitary structure comprising the second powder mixture; partially sintering the green unitary structure to form a brown unitary structure; machining threads into the tapered surface of the brown unitary structure-, placing the brown unitary structure in a mold; at least substantially filling a space defined between the brown unitary structure and the mold with metal or metal alloy particles; and infiltrating the brown unitary structure with a metal or a metal alloy by melting the metal or metal alloy particles to form the earth-boring rotary drill bit comprising the bit body and the pin secured to and integrally formed with the bit body.