Articles comprising metal, hard material, and an inoculant, and related methods
View Patent ↗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.
1. A partially formed earth-boring tool, comprising:
a body comprising a generally homogenous solution cast within a mold, wherein the generally homogeneous solution comprises:
a metal comprising between about 75% and about 90% by weight of the generally homogeneous solution;
an inoculant, and
particulate matter comprising a hard material, the hard material comprising a material having a Vickers Hardness of at least about 1200.
2. The partially formed earth-boring tool of claim 1 , wherein the inoculant comprises at least one material selected from the group consisting of transition metal aluminates, transition metal metasilicates, and transition metal oxides.
3. The partially formed earth-boring tool of claim 1 , wherein the inoculant comprises at least one material selected from the group consisting of cobalt aluminate, cobalt metasilicate, and cobalt oxide.
4. The partially formed earth-borin tool of claim 1 , wherein the metal comprises cobalt or a cobalt-based alloy, and the hard material comprises tungsten carbide.
5. The partially formed earth-boring tool of claim 1 , wherein the partially formed earth-boring tool comprises at least a portion of partially formed earth-boring rotary drill bit.
6. The partially formed earth-boring tool of claim 1 , comprising at least one mixed metal carbide phase comprising at least one of an M 6 C phase and an M 12 C phase, wherein M is at least one metal element, and C is carbon.
7. The partially formed earth-borin tool of claim 1 , wherein the at least one mixed metal carbide phase comprises an eta phase of W x Co y C, wherein X is from about 0.5 to about 6 and y is from about 0.5 to about 6.
8. The partially formed earth-boring tool of claim 1 , wherein the metal comprises cobalt or a cobalt-based alloy, wherein the generally homogenous solution comprises from about 75% to about 90% by weight the cobalt or cobalt-based alloy and from about 0.5% to about 3.8% carbon by weight, and wherein a balance of the generally homogenous solution comprising the particulate matter is at least substantially comprised of tungsten.
9. A method of forming an earth-boring tool, comprising:
intermixing a metal comprising between about 75% and about 90% by weight of a generally homogenous solution, particulate matter comprising a hard material, the hard material comprising a material having a Vickers Hardness of at least about 1200, and an inoculant; and
forming a cast, molten body comprising the generally homogenous solution, the generally homogeneous solution comprising the metal, the particulate matter, and the inoculant.
10. The method of claim 9 , further comprising disposing the generally homogenous solution within a cavity defined by a mold.
11. The method of claim 10 , wherein disposing the generally homogenous solution within a cavity comprises disposing the solution within a cavity defined by a mold comprising at least one material selected from the group consisting of graphite and ceramics.
12. The method of claim 9 , further comprising forming a solid comprising the metal, the hard material, and the inoculant by permitting the cast, molten body to solidify.
13. The method of claim 9 , further comprising forming a metal phase and a hard material phase.
14. The method of claim 13 , wherein forming a metal phase and a hard material phase comprises forming a carbide phase.
15. The method of claim 13 , further comprising heating the metal phase and the hard material phase to a temperature between 800° C. and about 1225° C.
16. The method of claim 13 , further comprising subjecting the metal phase and the hard material phase to a vacuum.
17. The method of claim 13 , further comprising exposing the metal phase and the hard material phase to an atmosphere comprising hydrogen and methane.
18. The method of claim 10 , further comprising vibrating the mold after intermixing the metal, the particulate matter, and the inoculant, and before forming the generally homogenous solution.
19. The method of claim 10 , further comprising providing excess particulate matter over the cavity defined by the mold before forming the generally homogenous solution.