A cBN sintered compact includes a binder phase that contains a TiAl alloy containing at least one of the Si, Mg, and Zn elements, Ti.sub.2CN, TiB.sub.2, AlN, and Al.sub.2O.sub.3; the ratio I.sub.Ti2CN/I.sub.TiAl is 2.0 or more and 30.0 or less, wherein I.sub.Ti2CN represents the intensity of the Ti.sub.2CN peak appearing at 2? from 41.9? to 42.2? and I.sub.TiAl represents the intensity of the TiAl alloy peak appearing at 2? from 39.0? to 39.3? in XRD; and, in the mapped image of each element of Ti, Al, Si, Mg, and Zn by Auger electron spectroscopy, the ratio S.sub.TiAlM/S.sub.TiAl, is 0.05 or more and 0.98 or less wherein S.sub.TiAlM represents the average area of the portions wherein Ti, Al and at least one selected from the group consisting of Si, Mg, and Zn overlap and S.sub.TiAl represents the average area of the portions where Ti and Al overlap.

A composite sintered material includes: a plurality of diamond grains having an average grain size of less than or equal to 10 m; a plurality of cubic boron nitride grains having an average grain size of less than or equal to 2 m; and a plurality of aluminum oxide grains having an average grain size of less than or equal to 0.5 m; and a remainder of a binder phase, wherein at least parts of adjacent diamond grains are bound to one another, the binder phase includes cobalt, in the composite sintered material, a content of the diamond grains is from 30 to 92 volume %, a content of the cubic boron nitride grains is from 3 to 40 volume %, a content of the aluminum oxide grains is from 2 to 15 volume %, and a content of the cobalt is from 3 to 30 volume %.

Polycrystalline diamond may include a working surface and a peripheral surface extending around an outer periphery of the working surface. The polycrystalline diamond includes a first volume including an interstitial material and a second volume having a leached region that includes boron and titanium. A method of fabricating a polycrystalline diamond element may include positioning a first volume of diamond particles adjacent to a substrate, the first volume of diamond particles including a material that includes a group 13 element, and positioning a second volume of diamond particles adjacent to the first volume of diamond particles such that the first volume of diamond particles is disposed between the second volume of diamond particles and the substrate, the second volume of diamond particles having a lower concentration of material including the group 13 element than the first volume of diamond particles.

A composite sintered material includes: a plurality of diamond grains having an average grain size of less than or equal to 10 m; a plurality of cubic boron nitride grains having an average grain size of less than or equal to 2 m; and a remainder of a binder phase, wherein at least parts of adjacent diamond grains are bound to one another, the binder phase includes cobalt, in the composite sintered material, a content of the diamond grains is more than or equal to 30 volume % and less than or equal to 94 volume %, a content of the cubic boron nitride grains is more than or equal to 3 volume % and less than or equal to 40 volume %, and a content of the cobalt is more than or equal to 3 volume % and less than or equal to 30 volume %.

A polycrystalline diamond compact includes a polycrystalline diamond material having a plurality of grains of diamond bonded to one another by inter-granular bonds and an intermetallic gamma prime () or -carbide phase disposed within interstitial spaces between the inter-bonded diamond grains. The ordered intermetallic gamma prime () or -carbide phase includes a Group VIII metal, aluminum, and a stabilizer. An earth-boring tool includes a bit body and a polycrystalline diamond compact secured to the bit body. A method of forming polycrystalline diamond includes subjecting diamond particles in the presence of a metal material comprising a Group VIII metal and aluminum to a pressure of at least 4.5 GPa and a temperature of at least 1,000 C. to form inter-granular bonds between adjacent diamond particles, cooling the diamond particles and the metal material to a temperature below 500 C., and forming an intermetallic gamma prime () or -carbide phase adjacent the diamond particles.

A thixotropically molded product includes: a matrix portion containing Mg as a main component; and a first particle portion dispersed in the matrix portion and containing c-BN or w-BN as a main component. An average particle diameter of the first particle portion in a cross section is 10.0 ?m or less, and an area fraction of the first particle portion in the cross section is 2.0% or more and 20.0% or less.

An aluminum-diamond composite that exhibits both high thermal conductivity and a coefficient of thermal expansion close to that of semiconductor devices, and that can suppress the occurrence of swelling, etc., of a surface metal layer portion even in actual use under a high load. An aluminum-diamond composite includes 65-80 vol % of a diamond powder having a roundness of at least 0.94, for which a first peak in a volumetric distribution of grain size lies at 5-25 m, and a second peak lies at 55-195 m, and a ratio between the area of the volumetric distribution of grain sizes of 1-35 m and the area of the volumetric distribution of grain sizes of 45-205 m is from 1:9 to 4:6; the balance being composed of a metal containing aluminum.

A polycrystalline diamond compact includes a polycrystalline diamond material having a plurality of grains of diamond bonded to one another by inter-granular bonds and an intermetallic gamma prime () or -carbide phase disposed within interstitial spaces between the inter-bonded diamond grains. The ordered intermetallic gamma prime () or -carbide phase includes a Group VIII metal, aluminum, and a stabilizer. An earth-boring tool includes a bit body and a polycrystalline diamond compact secured to the bit body. A method of forming polycrystalline diamond includes subjecting diamond particles in the presence of a metal material comprising a Group VIII metal and aluminum to a pressure of at least 4.5 GPa and a temperature of at least 1,000 C. to form inter-granular bonds between adjacent diamond particles, cooling the diamond particles and the metal material to a temperature below 500 C., and forming an intermetallic gamma prime () or -carbide phase adjacent the diamond particles.

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 drilling tip according to the disclosure has a tip body which is provided with a tip portion tapered toward a tip side of the tip body; and a hard layer which is formed on a surface of the tip portion of the tip body, an outermost layer of the hard layer is a cBN sintered material having 70 to 95 vol % of cBN grains, and when a cross-sectional structure of the outermost layer is observed, a binder phase having a width of 1 nm or greater and 30 nm or less and containing Al, B, and N, and in which a ratio of an O content to an Al content is 0.1 or less exists between neighboring cBN grains.