Methods for manufacturing downhole tools and downhole tool parts

1. A method of manufacturing a downhole tool part for drilling subterranean material, comprising:

fabricating a model having an external peripheral shape of a downhole tool part;

positioning at least one bit body element at the external periphery of the model;

applying a mold material to at least a portion of the external periphery of the model and at least a portion of the at least one bit body element;

permitting the mold material to harden to form a mold about the model;

eliminating the model from within the mold and leaving the at least one bit body element within the mold; and

casting a composite matrix material within the mold to form the downhole tool part and incorporate the at least one bit body element into the downhole tool part.

2. The method as recited in claim 1 , further comprising providing a particulate material within the mold prior to casting the composite matrix material within the mold.

3. The method as recited in claim 2 , further comprising selecting the particulate material to comprise at least one constituent selected from the group consisting of:

monotungsten carbide (WC), ditungsten carbide (W 2 C), macro-crystalline tungsten carbide, cobalt, titanium carbide, tantalum carbide, metal borides, metal oxides, metal nitrides, polycrystalline diamond compact (PDC), thermally stable polycrystalline diamond (TSP), cubic boron nitride (CBN), polycrystalline cubic boron nitride (PCBN), tungsten, iron, nickel, titanium and boron carbide.

4. The method as recited in claim 3 , further comprising selecting the particulate material to increase at least one of wear resistance, strength and toughness of a selective surface of the downhole tool part formed from casting the composite matrix material within the mold.

5. The method as recited in claim 1 , wherein eliminating the model from within the mold includes at least one of burning, melting, vaporizing and dissolving the model.

6. The method as recited in claim 1 , further comprising selecting the composite matrix material to comprise tungsten carbide and cobalt.

7. The method as recited in claim 6 , further comprising selecting the composite matrix material to have a tungsten carbide content of about 25 atomic percent and a cobalt content of about 75 atomic percent.

8. The method as recited in claim 6 , further comprising selecting the composite matrix material to have a cobalt content equal to or greater than about 70 atomic percent.

9. The method as recited in claim 1 , further comprising selecting the at least one bit body element to comprise at least one of a cutting element, a bearing structure, a gage trimmer, a nozzle and a cutting control structure.

10. The method as recited in claim 9 , further comprising selecting the at least one bit body element to comprise tungsten carbide and cobalt.

11. The method as recited in claim 10 , further comprising selecting the at least one bit body element to have a cobalt content less than 20 weight percent.

12. The method as recited in claim 1 , further comprising casting the composite matrix material under vacuum conditions.

13. The method as recited in claim 1 , further comprising casting the composite matrix material in a protective atmosphere.

14. The method as recited in claim 13 , further comprising selecting the protective atmosphere to comprise one of an inert atmosphere and a reducing atmosphere.

15. The method as recited in claim 1 , further comprising casting the composite matrix material in air.

16. The method as recited in claim 1 , further comprising selecting the composite matrix material to comprise a eutectic composition of at least two constituents selected from the group consisting of monotungsten carbide (WC), ditungsten carbide (W 2 C), cobalt, tungsten, iron, nickel, titanium and boron carbide.

17. The method as recited in claim 16 , further comprising casting the composite matrix material at or above a eutectic temperature of the eutectic composition of the composite matrix material.

18. A method of manufacturing a downhole tool part for drilling subterranean material, comprising:

fabricating a model having an external peripheral shape of a downhole tool part;

positioning at least one bit body element at the external periphery of the model;

applying a mold material to at least a portion of the external periphery of the model and at least a portion of the at least one bit body element;

permitting the mold material to harden to form a mold about the model;

eliminating the model from within the mold and leaving the at least one bit body element within the mold; and

casting a composite matrix material within the mold to form the downhole tool part and incorporate the at least one bit body element into the downhole tool part, the composite matrix material comprising a eutectic composition of at least two constituents selected from the group consisting of monotungsten carbide (WC), ditungsten carbide (W 2 C), cobalt, tungsten, iron, nickel, titanium, and boron carbide.

19. The method as recited in claim 18 , further comprising casting the composite matrix material at or above a eutectic temperature of the eutectic composition of the composite matrix material.

20. The method as recited in claim 18 , further comprising forming the downhole tool part to comprise a drill bit body.

21. The method as recited in claim 18 , further comprising forming the downhole tool part to comprise a roller cone.

22. The method as recited in claim 21 , further comprising selecting the at least one bit body element to comprise at least one of a cutting insert and a bearing element.

23. The method as recited in claim 22 , further comprising selecting the at least one bit body element to comprise a cutting insert including tungsten carbide and cobalt.

24. The method as recited in claim 23 , further comprising selecting the cutting insert to have a cobalt content less than 20 weight percent.