Embodiments relate to polycrystalline diamond compacts (PDCs) including a substrate and a polycrystalline diamond (PCD) table mounted to the substrate. The PCD table includes an upper surface and one or more recesses extending inwardly from the upper surface of the PCD table. The one or more recesses may help prevent, stop, or limit crack propagation and may redistribute, breakup, or relieve stresses in the PCD table. In some embodiments, the one or more recesses exhibit, in plain view, a generally rectangular geometry, a generally circular geometry, or a generally triangular geometry. In some embodiments, the PCD table includes one or more channels that extend from a vertex of the one or more recesses. In some embodiments, the one or more channels and the one or more recesses may be at least partially filled with a sacrificial material. Methods for forming such PDCs are also discussed.

Bearings for earth-boring tools may include a first bearing member including a first bearing pad having a first contact surface and a second bearing member including a second bearing pad having a second contact surface in sliding contact with at least a portion of the first contact surface. At least one of the first bearing member and the second bearing member may include a polycrystalline table attached to a portion of a first substrate on which the polycrystalline table was formed. Another substrate may be attached to the portion of the first substrate, the portion of the first substrate interposed between the polycrystalline table and the other substrate. The portion of the first substrate may include a first volume percentage of the first matrix material and the other substrate may include a second, different volume percentage of the second matrix material

A method of processing a superabrasive element includes providing a superabrasive element including a polycrystalline diamond table that includes a metallic material disposed in interstitial spaces defined within the polycrystalline diamond table. The method also includes leaching the metallic material from at least a volume of the polycrystalline diamond table to produce a leached volume in the polycrystalline diamond table.

Methods of forming a polycrystalline compact using at least one metal salt as a sintering aid. Such methods may include forming a mixture of the at least one metal salt and a plurality of grains of hard material and sintering the mixture to form a hard polycrystalline material. During sintering, the metal salt may melt or react with another compound to form a liquid that acts as a lubricant to promote rearrangement and packing of the grains of hard material. The metal salt may, thus, enable formation of hard polycrystalline material having increased density, abrasion resistance, or strength. The metal salt may also act as a getter to remove impurities (e.g., catalyst material) during sintering. The methods may also be employed to form cutting elements and earth-boring tools.

Methods for manufacturing a matrix tool body comprising placing a first matrix material within a first region of a mold cavity proximate a surface of the mold. A second matrix material may be placed within a second region of the mold cavity positioned inwardly of the first matrix material. The first matrix material and the second matrix material comprise a plurality of hard particles. The plurality of hard particles of the second matrix material have a median particle size that is less than the median particle size of the first matrix material. The plurality of hard particles of the first matrix material and the second matrix material are infiltrated with an infiltration binder to form the tool body. Also included are tool bodies having one or more regions proximate a surface of the tool body comprising an erosion resistant matrix material and/or a wear resistant matrix material.

A superhard polycrystalline construction comprises a body of polycrystalline superhard material comprising a structure comprising superhard material, the structure having porosity greater than 20% by volume and up to around 80% by volume. A method of forming such a superhard polycrystalline construction comprises forming a skeleton structure of a first material having a plurality of voids, at least partially filling some or all of the voids with a second material to form a pre-sinter assembly, and treating the pre-sinter assembly to sinter together grains of superhard material to form a body of polycrystalline superhard material comprising a first region of superhard grains, and an interpenetrating second region; the second region being formed of the other of the first or second material that does not comprise the superhard grains; the superhard grains forming a sintered structure having a porosity greater than 20% by volume and up to around 80% by volume.

A polycrystalline diamond compact (PDC), which is attached or bonded to a substrate to form a cutter for a drill bit, is comprised of sintered polycrystalline diamond interspersed with a seed material which has a hexagonal close packed (HCP) crystalline structure. A region of the sintered polycrystalline diamond structure, near one or more of its working surfaces, which has been seeded with an HCP seed material prior to sintering, is leached to remove catalyst. Selectively seeding portions or regions of a sintered polycrystalline diamond structure permits differing leach rates to form leached regions with differing distances or depths and geometries.

A superabrasive cutter and a method of making the superabrasive cutter are disclosed. The superabrasive cutter may comprise a plurality of polycrystalline superabrasive particles and about 0.01% to about 4% by weight of the superabrasive particles of a dopant as evaluated prior to a high pressure/high temperature process. The dopant may be immiscible with a catalyst for forming the polycrystalline superabrasive particles.

Methods of forming a polycrystalline compact using at least one metal salt as a sintering aid. Such methods may include forming a mixture of the at least one metal salt and a plurality of grains of hard material and sintering the mixture to form a hard polycrystalline material. During sintering, the metal salt may melt or react with another compound to form a liquid that acts as a lubricant to promote rearrangement and packing of the grains of hard material. The metal salt may, thus, enable formation of hard polycrystalline material having increased density, abrasion resistance, or strength. The metal salt may also act as a getter to remove impurities (e.g., catalyst material) during sintering. The methods may also be employed to form cutting elements and earth-boring tools.

Cutting elements include at least one metal diffused into interbonded grains of diamond. Earth-boring tools include at least one such cutting element. Methods of forming cutting elements may include forming a mixture of the at least one metal salt and a plurality of grains of hard material and sintering the mixture to form a hard polycrystalline material. During sintering, the metal salt may melt or react with another compound to form a liquid that acts as a lubricant to promote rearrangement and packing of the grains of hard material. The metal salt may, thus, enable formation of hard polycrystalline material having increased density, abrasion resistance, or strength. The metal salt may also act as a getter to remove impurities (e.g., catalyst material) during sintering. The methods may also be employed to form cutting elements and earth-boring tools.