A method of manufacturing a rotary drill bit includes forming a mold having an inner surface and an outer surface, locating a metal mandrel within the mold, packing the mold around at least part of the mandrel with particulate matrix-forming material and installing an insulating material around at least an upper portion of the outer surface. The material is infiltrated in a furnace with a molten binding alloy and the mold including the insulating material is removed from the furnace, directionally solidifying the material and binding alloy in portion of the bit, wherein the directional solidification proceeds from the lower portion of the outer surface in an upward and outward direction to form a solid infiltrated matrix bonded to the mandrel by cooling of the mold with the insulating material disposed around at least the upper portion of the outer surface of the mold.

A method of manufacturing a rotary drill bit includes forming a mold having an inner surface and an outer surface, locating a metal mandrel within the mold, packing the mold around at least part of the mandrel with particulate matrix-forming material and installing an insulating material around at least an upper portion of the outer surface. The material is infiltrated in a furnace with a molten binding alloy and the mold including the insulating material is removed from the furnace, directionally solidifying the material and binding alloy in portion of the bit, wherein the directional solidification proceeds from the lower portion of the outer surface in an upward and outward direction to form a solid infiltrated matrix bonded to the mandrel by cooling of the mold with the insulating material disposed around at least the upper portion of the outer surface of the mold.

A method of forming an earth-boring tool includes introducing metal into a die, rotating the die to generate centrifugal forces on the metal, and cooling the metal in the rotating die. A rotary drill bit may include a unitary, centrifugally cast bit body including an integral shank, at least one blade, and at least one cutting element on the blade. A rotary drill bit or a roller cone may include a first centrifugally cast material and a second centrifugally cast material. Another rotary drill bit includes a bit body comprising a maraging steel alloy. A method of forming a rotary drill bit may include disposing cutting elements on a rotary drill bit comprising maraging steel and aging the rotary drill bit to form at least one intermetallic precipitate phase. Methods of repairing a rotary drill bit include annealing and aging at least a portion of a rotary drill bit.

A method of forming an earth-boring tool includes introducing metal into a die, rotating the die to generate centrifugal forces on the metal, and cooling the metal in the rotating die. A rotary drill bit may include a unitary, centrifugally cast bit body including an integral shank, at least one blade, and at least one cutting element on the blade. A rotary drill bit or a roller cone may include a first centrifugally cast material and a second centrifugally cast material. Another rotary drill bit includes a bit body comprising a maraging steel alloy. A method of forming a rotary drill bit may include disposing cutting elements on a rotary drill bit comprising maraging steel and aging the rotary drill bit to form at least one intermetallic precipitate phase. Methods of repairing a rotary drill bit include annealing and aging at least a portion of a rotary drill bit.

An example system for fabricating an infiltrated downhole tool includes a mold assembly having one or more component parts and defining an infiltration chamber to receive and contain matrix reinforcement materials and a binder material used to form the infiltrated downhole tool. One or more thermal conduits are positioned within the one or more component parts for circulating a thermal fluid through at least one of the one or more component parts and thereby placing the thermal fluid in thermal communication with the infiltration chamber.

An example system for fabricating an infiltrated downhole tool includes a mold assembly having one or more component parts and defining an infiltration chamber to receive and contain matrix reinforcement materials and a binder material used to form the infiltrated downhole tool. One or more thermal conduits are positioned within the one or more component parts for circulating a thermal fluid through at least one of the one or more component parts and thereby placing the thermal fluid in thermal communication with the infiltration chamber.

A metal matrix composite to high tolerate wear as a property has been produced by infiltration casting of a Fe Alloy and a spinel ceramic by using a material design for i) metal transport phenomena conditions, ii) predefined wetting and capillarity and iii) processing child insert/mother casting methodology to produce a final casting in shape and form to meet the needs of a mining end user.

Methods of forming at least a portion of an earth-boring tool include providing particulate matter including a hard material in a mold cavity, melting a metal and the hard material to form a molten composition comprising a eutectic or near-eutectic composition of the metal and the hard material, casting the molten composition to form the at least a portion of an earth-boring tool within the mold cavity, and providing an inoculant within the mold cavity. Methods of forming a roller cone of an earth-boring rotary drill bit include forming a molten composition, casting the molten composition within a mold cavity, solidifying the molten composition to form the roller cone, and controlling grain growth using an inoculant as the molten composition solidifies. Articles including components of earth-boring tools are fabricated using such methods.

Methods of forming at least a portion of an earth-boring tool include providing particulate matter including a hard material in a mold cavity, melting a metal and the hard material to form a molten composition comprising a eutectic or near-eutectic composition of the metal and the hard material, casting the molten composition to form the at least a portion of an earth-boring tool within the mold cavity, and providing an inoculant within the mold cavity. Methods of forming a roller cone of an earth-boring rotary drill bit include forming a molten composition, casting the molten composition within a mold cavity, solidifying the molten composition to form the roller cone, and controlling grain growth using an inoculant as the molten composition solidifies. Articles including components of earth-boring tools are fabricated using such methods.

An example mold assembly system includes a mold assembly including a mold forming a bottom of the mold assembly, a funnel operatively coupled to the mold, and an infiltration chamber defined at least partially by the mold and the funnel, the infiltration chamber being used for forming an infiltrated downhole tool. A mold assembly cap is positionable on the mold assembly and including a sidewall extendable about an outer periphery of the mold assembly at least partially along a height of the mold assembly. The sidewall exhibits a horizontal cross-sectional shape that accommodates a shape of the mold assembly and the sidewall is made of a thermal material that promotes directional solidification of the infiltrated downhole tool during fabrication.