Methods of forming a polycrystalline diamond compact for use in an earth-boring tool include forming a body of polycrystalline diamond material including a first material disposed in interstitial spaces between inter-bonded diamond crystals in the body, removing the first material from interstitial spaces in a portion of the body, selecting a second material promoting a higher rate of degradation of the polycrystalline diamond compact than the first material under similar elevated temperature conditions and providing the second material in interstitial spaces in the portion of the body. Methods of drilling include engaging at least one cutter with a formation and wearing a second region of polycrystalline diamond material comprising a second material faster than the first region of polycrystalline diamond material comprising a first material. Polycrystalline diamond compacts and earth-boring tools including such compacts.

Methods of forming a polycrystalline diamond compact for use in an earth-boring tool include forming a body of polycrystalline diamond material including a first material disposed in interstitial spaces between inter-bonded diamond crystals in the body, removing the first material from interstitial spaces in a portion of the body, selecting a second material promoting a higher rate of degradation of the polycrystalline diamond compact than the first material under similar elevated temperature conditions and providing the second material in interstitial spaces in the portion of the body. Methods of drilling include engaging at least one cutter with a formation and wearing a second region of polycrystalline diamond material comprising a second material faster than the first region of polycrystalline diamond material comprising a first material. Polycrystalline diamond compacts and earth-boring tools including such compacts.

Zonal heating and cooling during the production of matrix drill bits may be achieved with a system that includes a cavity defined within a mold assembly having a central axis; reinforcing particles and a binder material disposed within the cavity; and a plurality of induction coils about a periphery of the mold assembly, each induction coil being spaced from each other along the height of the mold assembly, wherein a first induction coil of the plurality of induction coils is arranged proximal to a portion of mold assembly containing a portion of the reinforcing particles and a second induction coil of the plurality of induction coils is arranged proximal to a portion of the mold assembly containing a portion of the binder material.

A method of forming a super hard polycrystalline construction comprises forming a liquid suspension of a first mass of nano-ceramic particles and a mass of particles or grains of super hard material having an average particle or grain size of 1 or more microns, dispersing the particles or grains in the liquid suspension to form a substantially homogeneous suspension, drying the suspension to form an admix of the nano-ceramic and super hard grains or particles, and forming a pre-sinter assembly comprising the admix. The pre-sinter assembly is then sintered to form a body of polycrystalline super hard material comprising a first fraction of super hard grains and a second fraction, the nano-ceramic particles forming the second fraction.

The super hard grains are spaced along at least a portion of the peripheral surface by one or more nano-ceramic grains, the super hard grains having a greater average grain size than that of the grains in the second fraction which have an average size of less than around 999 nm.

A method of forming a super hard polycrystalline construction comprises forming a liquid suspension of a first mass of nano-ceramic particles and a mass of particles or grains of super hard material having an average particle or grain size of 1 or more microns, dispersing the particles or grains in the liquid suspension to form a substantially homogeneous suspension, drying the suspension to form an admix of the nano-ceramic and super hard grains or particles, and forming a pre-sinter assembly comprising the admix. The pre-sinter assembly is then sintered to form a body of polycrystalline super hard material comprising a first fraction of super hard grains and a second fraction, the nano-ceramic particles forming the second fraction.

The super hard grains are spaced along at least a portion of the peripheral surface by one or more nano-ceramic grains, the super hard grains having a greater average grain size than that of the grains in the second fraction which have an average size of less than around 999 nm.

A tip (20) for a rotary machine tool comprising a superhard structure (12) joined to a cemented carbide substrate 14 by means of at least one intermediate layer (161, 62, 163) disposed between the superhard structure (12) and the cemented carbide substrate (14), the intermediate layer or layers (161, 162, 163) comprising grains of superhard material and grains of a metal carbide material dispersed in a metal binder material.

A tip (20) for a rotary machine tool comprising a superhard structure (12) joined to a cemented carbide substrate 14 by means of at least one intermediate layer (161, 62, 163) disposed between the superhard structure (12) and the cemented carbide substrate (14), the intermediate layer or layers (161, 162, 163) comprising grains of superhard material and grains of a metal carbide material dispersed in a metal binder material.

A cutting element may include a substrate and a volume of polycrystalline diamond material affixed to the substrate at an interface. The volume of polycrystalline diamond may include a front cutting face with at least one substantially planar portion and at least one recess. The at least one recess may extend from a plane defined by the at least one substantially planar portion a first depth into the volume of polycrystalline diamond material in an axial direction parallel to a central axis of the cutting element. The volume of polycrystalline diamond material may comprise a region including a catalyst material. At least one region substantially free of the catalyst material may extend from the at least one substantially planar portion of the front cutting face a second depth into the volume of polycrystalline diamond in the axial direction. Methods of forming cutting elements.

A method of forming a super hard polycrystalline construction comprises forming a liquid suspension of nano-sized super hard particles and particles of super hard material having an average particle or grain size of 1 or more microns, dispersing the particles in the liquid suspension to form a substantially homogeneous suspension which is then dried and sintered to form a body of polycrystalline super hard material comprising a first and second fractions of super hard grains, the nano-sized particles forming the second fraction. The super hard grains in the first fraction are bonded along at least a portion of the peripheral surface(s) thereof to at least a portion of a plurality of nano-sized grains in the second fraction, the grains in the first fraction having a greater average grain size than that of the grains in the second fraction which is less than 999 nm, the average grain size of the first fraction being around 1 micron or more

A method of forming a super hard polycrystalline construction comprises forming a liquid suspension of nano-sized super hard particles and particles of super hard material having an average particle or grain size of 1 or more microns, dispersing the particles in the liquid suspension to form a substantially homogeneous suspension which is then dried and sintered to form a body of polycrystalline super hard material comprising a first and second fractions of super hard grains, the nano-sized particles forming the second fraction. The super hard grains in the first fraction are bonded along at least a portion of the peripheral surface(s) thereof to at least a portion of a plurality of nano-sized grains in the second fraction, the grains in the first fraction having a greater average grain size than that of the grains in the second fraction which is less than 999 nm, the average grain size of the first fraction being around 1 micron or more