Polycrystalline compacts including interbonded nanoparticles, cutting elements and earth-boring tools including such polycrystalline compacts, and related methods

1. A polycrystalline compact, comprising:

a polycrystalline hard material comprising interbonded grains of hard material; and

interbonded nanoparticles of non-carbide-forming material within interstitial spaces between the interbonded grains of the hard material, at least a portion of the interbonded nanoparticles of non-carbide-forming material interbonded with the interbonded grains of hard material.

2. The polycrystalline compact of claim 1 , further comprising at least one of cobalt, nickel, and iron at least partially surrounding the interbonded nanoparticles of non-carbide-forming material within at least a portion of the interstitial spaces.

3. The polycrystalline compact of claim 2 , wherein the at least one of cobalt, nickel, and iron is substantially absent from a portion of the polycrystalline hard material.

4. The polycrystalline compact of claim 1 , wherein substantially all of the interstitial spaces are substantially free of cobalt, nickel, and iron.

5. The polycrystalline compact of claim 1 , wherein the polycrystalline hard material comprises diamond.

6. The polycrystalline compact of claim 1 , wherein the interbonded nanoparticles of non-carbide-forming material comprise one or more of elemental rhenium, elemental molybdenum, elemental osmium, elemental ruthenium, elemental rhodium, elemental iridium, elemental platinum, alloys thereof, scandium tungstate, and zirconium tungstate.

7. A cutting element, comprising:

a substrate; and

the polycrystalline compact of claim 1 over and attached to the substrate.

8. An earth-boring tool, comprising:

a body; and

cutting elements carried by the body, at least one of the cutting elements comprising the polycrystalline compact of claim 1 .

9. A polycrystalline compact, comprising:

a polycrystalline hard material comprising interbonded grains of hard material; and

interbonded nanoparticles of non-carbide-forming material comprising rhenium within interstitial spaces between the interbonded grains of the hard material, at least a portion of the interbonded nanoparticles of non-carbide-forming material interbonded with the interbonded grains of hard material.

10. The polycrystalline compact of claim 9 , wherein at least a portion of the interbonded nanoparticles of non-carbide-forming material further comprise at least one of molybdenum, osmium, ruthenium, rhodium, iridium, platinum, scandium tungstate, and zirconium tungstate.

11. A polycrystalline compact, comprising:

a polycrystalline hard material comprising interbonded grains of diamond; and

interbonded nanoparticles comprising one or more elemental rhenium, elemental molybdenum, elemental osmium, elemental ruthenium, elemental rhodium, elemental iridium, elemental platinum, and an alloy thereof within interstitial spaces between the interbonded grains of diamond, at least a portion of the interbonded nanoparticles interbonded with the interbonded grains of diamond.

12. A method of forming a polycrystalline compact, comprising:

forming a polycrystalline hard material comprising interbonded grains of hard material; and

forming interbonded nanoparticles of non-carbide-forming material within interstitial spaces between the interbonded grains of the hard material, at least a portion of the interbonded nanoparticles of non-carbide-forming material interbonded with the interbonded grains of hard material.

13. The method of claim 12 , wherein forming a polycrystalline hard material comprises:

forming nanoparticles of the non-carbide-forming material on particles of the hard material; and

sintering the nanoparticles of the non-carbide-forming material and the particles of the hard material.

14. The method of claim 13 , wherein forming nanoparticles of the non-carbide-forming material on particles of the hard material comprises functionalizing surfaces of at least one of the nanoparticles of the non-carbide-forming material and the particles of the hard material.

15. The method of claim 12 , wherein forming a polycrystalline hard material comprises:

forming an admixture comprising nanoparticles of the non-carbide-forming material and particles of the hard material; and

sintering the admixture.

16. The method of claim 12 , further comprising forming at least one of cobalt, nickel, and iron within at least a portion of the interstitial spaces.

17. The method of claim 16 , wherein forming at least one of cobalt, nickel, and iron within at least a portion of the interstitial spaces comprises:

forming nanoparticles of the non-carbide-forming material on particles of the at least one of cobalt, nickel, and iron to form coated particles;

combining the coated particles with particles of the hard material; and

sintering the coated particles and particles of the hard material.

18. The method of claim 12 , wherein forming interbonded nanoparticles of non-carbide-forming material comprises forming the interbonded nanoparticles of non-carbide-forming material to comprise one or more of elemental rhenium, elemental molybdenum, elemental osmium, elemental ruthenium, elemental rhodium, elemental iridium, elemental platinum, alloys thereof, scandium tungstate, and zirconium tungstate.

19. A method of forming a cutting element, comprising:

forming a polycrystalline compact according to the method of claim 12 ; and

attaching the polycrystalline compact to a substrate.

20. A method of forming an earth-boring tool, comprising:

forming at least one cutting element according to the method of claim 19 ; and

attaching the at least one cutting element to a body.