Polycrystalline compacts having material disposed in interstitial spaces therein, cutting elements and earth-boring tools including such compacts, and methods of forming such compacts

A polycrystalline compact, comprising:

• a first plurality of grains of hard material having a first average grain size;
• and
• at least a second plurality of grains of hard material having a second average grains size that is at least about one hundred and fifty (150) times larger than the first average grain size of the first plurality of grains, the first plurality of grains and the at least a second plurality of grains being interspersed and interbonded to form a polycrystalline hard material,
• wherein the polycrystalline hard material further comprises an interstitial material disposed in at least some interstitial spaces between the first plurality of grains and the at least a second plurality of grains of the polycrystalline hard material, the interstitial material comprising at least one of a boride, a carbide, a nitride, a metal carbonate, a metal bicarbonate, and a non-catalytic metal.

A cutting element, comprising:

• a substrate;
• and
• a polycrystalline compact on the substrate, the polycrystalline compact comprising:
• a plurality of interspersed and interbonded grains of hard material forming a polycrystalline hard material, wherein the grains of the plurality of interspersed and interbonded grains comprise a first plurality of grains having a first average grain size and at least a second plurality of grains having a second average grain size at least one hundred and fifty (150) times larger than the first average grain size;
• and
• an interstitial material disposed in at least some interstitial spaces between the interbonded grains of the polycrystalline hard material, the interstitial material comprising at least one of a boride, a carbide, a nitride, a metal carbonate, a metal bicarbonate, and a non-catalytic metal.

An earth-boring drill bit, comprising:

• a bit body;
• and
• a plurality of cutting elements attached to the bit body, at least one cutting element of the plurality of cutting elements comprising a hard polycrystalline material including:
• a first plurality of grains having a first average grain size;
• at least a second plurality of grains having a second average grain size at least one hundred and fifty (150) times larger than the first average grain size of the first plurality of grains, the first plurality of grains and the second plurality of grains being interspersed and interbonded with one another to form a polycrystalline hard material;
• and
• an interstitial material disposed in at least some interstitial spaces between the interspersed and interbonded grains of the polycrystalline hard material, the interstitial material comprising at least one of a boride, a carbide, a nitride, a metal carbonate, a metal bicarbonate, and a non-catalytic metal.

A method of forming a polycrystalline compact, comprising:

• at least partially coating each particle of a first plurality of particles of hard material having a first average particle size with a coating material comprising at least one of a boride, a carbide, a nitride, a metal carbonate, a metal bicarbonate, and a non-catalytic metal;
• dispersing the first plurality of particles among at least a second plurality of particles of hard material having a second average particle size larger than the first average particle size of the first plurality of particles;
• sintering the first plurality of particles and the at least a second plurality of particles to form a polycrystalline hard material comprising a first plurality of grains formed from the first plurality of particles and a second plurality of grains formed from the second plurality of particles, the first plurality of grains and the second plurality of grains being interspersed and interbonded to form the polycrystalline hard material;
• and
• selecting the first average particle size of the first plurality of particles and the second average particle size of the second plurality of particles to cause the second plurality of grains to have a second average grain size at least about one hundred and fifty (150) times larger than a first average grain size of the first plurality of grains.