Polycrystalline diamond cutting elements having improved thermal resistance

A polycrystalline diamond construction comprising:

• a polycrystalline diamond body having a material microstructure comprising a plurality of bonded-together diamond crystals forming a polycrystalline matrix phase, and an intermetallic compound interposed within a boundary phase between the bonded-together diamond crystals, wherein the intermetallic compound comprises a combination or reaction product of one or more materials selected from Group VIII of the Periodic Table, with Cr, Mn, Ti, Zr, Hf, V, Nb, Mo, W, Ta, and alloys thereof, wherein the polycrystalline diamond body is substantially free of a material consisting exclusively of a Group VIII element of the Periodic table;
• and
• a substrate attached to the polycrystalline diamond construction, wherein the substrate is formed from a material selected from the group consisting of ceramics, metals, cermets, and combinations thereof that are substantially free of a Group VIII element of the Periodic table;
• wherein the polycrystalline diamond construction is prepared by the process of:
• placing the diamond powder within a container that is sealed off from the atmosphere;
• sintering the diamond powder in the presence of the materials used to form the intermetallic compound under high pressure conditions of greater than about 55 Kbar, and under high temperature conditions to form the polycrystalline diamond construction, wherein some or all of the materials used to form the intermetallic compound is present in the diamond grains forming the diamond powder;
• and
• attaching the polycrystalline diamond construction to the substrate.

A polycrystalline diamond construction comprising:

• a polycrystalline diamond body having a material microstructure comprising a plurality of bonded-together diamond crystals forming a polycrystalline matrix phase, and an intermetallic compound interposed within a boundary phase between the bonded-together diamond crystals, wherein the intermetallic compound comprises a combination or reaction product of one or more materials selected from Group VIII of the Periodic Table, with Cr, Mn, Ti, Zr, Hf, V, Nb, Mo, W, Ta, and alloys thereof, wherein the polycrystalline diamond body is substantially free of a material consisting exclusively of a Group VIII element of the Periodic table, and has a diamond volume content of greater than about 96 percent;
• and
• a substrate attached to the polycrystalline diamond construction, wherein the substrate is formed from a material selected from the group consisting of ceramics, metals, cermets, and combinations thereof;
• wherein the polycrystalline diamond construction comprises a diamond content of about 96 percent by volume or more and is prepared by the process of:
• graphitizing part or all of a precursor diamond powder used to form the polycrystalline diamond body;
• placing the diamond powder within a container that is sealed off from the atmosphere;
• sintering the diamond powder in the presence of the materials used to form the intermetallic compound under high pressure conditions of greater than about 55 Kbar, and under high temperature conditions to form the polycrystalline diamond construction, wherein the materials used to form the intermetallic compound are combined with the diamond powder to form a mixture prior to sintering;
• and
• attaching the polycrystalline diamond construction to the substrate.

An earth boring drill bit comprising:

• a body and a number of cutting elements attached thereto, one or more of the cutting elements comprising a polycrystalline diamond construction that is formed from a plurality of bonded-together diamond crystals, wherein the polycrystalline diamond construction comprises:
• a polycrystalline diamond body having a diamond volume content of greater than about 94 percent;
• and
• a substrate attached to the polycrystalline diamond body, wherein the substrate is formed from a material selected from the group consisting of ceramics, metals, cermets, and combinations thereof;
• wherein the polycrystalline diamond construction is prepared by the process of:
• graphitizing part or all of a precursor diamond powder used to form the polycrystalline diamond construction;
• combining the graphitized diamond powder with a sintering agent comprising Pd and one or more further material selected from the group consisting of Fe, Co, Ni, to form a diamond powder mixture, wherein the Pd is disposed on a surface of diamond grains in the diamond powder and the one or more further material is disposed on the Pd, and wherein the Pd and one or more further materials are distributed homogeneously within the diamond powder mixture;
• sintering the diamond powder mixture under a high pressure condition of greater than about 55 Kbar and a high temperature condition;
• and
• attaching the diamond body to the substrate to form the polycrystalline diamond construction.

An earth boring drill bit comprising:

• a body having a number of cutting attached thereto, one or more of the cutting elements comprising a polycrystalline diamond construction comprising:
• a polycrystalline diamond body comprising a plurality of bonded-together diamond crystals;
• and
• a substrate attached to the polycrystalline diamond body, wherein the substrate is formed from a material selected from the group consisting of ceramics, metals, cermets, and combinations thereof;
• wherein the polycrystalline diamond construction is prepared by the process of:
• graphitizing part or all of a precursor diamond powder used to form the polycrystalline diamond body;
• combining the graphitized diamond powder with a sintering aid comprising a compound having one or more elements selected from the group consisting of Fe, Co, Ni, Mn, Ti, TiO2, Si, Alkali earth metals, Alkaline earth metals, rare earth elements, and O, wherein the compound is selected from the group consisting of silicates, titanates, and oxides, and wherein the diamond powder and the sintering aid is disposed within a container that is sealed off from the atmosphere;
• sintering the diamond powder and sintering aid under high pressure conditions of greater than about 70 Kbar, and under high temperature conditions to form the polycrystalline diamond body;
• and
• attaching the polycrystalline diamond body to the substrate.