Abstract: This disclosure relates to a two-piece friction stir welding (FSW) tool insert. The tool insert has a longitudinal axis of rotation and comprises a stirring pin and an annular shoulder coaxially mounted about the stirring pin. The stirring pin and annular shoulder each comprise polycrystalline cubic boron nitride. The annular shoulder is a thin disc with a thickness of 1 to 12 mm and the shoulder comprises a tapered, central aperture, through which the stirring pin protrudes.

Abstract: This disclosure relates a polycrystalline cubic boron nitride, PCBN, composite material for use in friction stir welding. The PCBN composite material comprises tungsten (W), rhenium (Re) and aluminium (Al) in the binder matrix material.

Abstract: PCBN material consisting of cBN grains dispersed in a matrix, the content of the cBN grains being in the range of about 35 to about 70 volume % of the PCBN material. The matrix comprises at least one kind of chemical compound that includes aluminium (Al) and at least one kind of chemical compound that includes titanium (Ti). The size distribution of the cBN grains exposed at a surface of the PCBN material is such that at least about 50% per cent of the total equivalent circle area (ECA) arises from cBN intercept lengths up to 5 microns. At least about 20 per cent of the total ECA arises from cBN intercept lengths greater than about 5 microns.

Abstract: A method of making a body of polycrystalline superhard material comprising placing an aggregated mass of grains of superhard material into a canister, placing a ceramic layer either in direct contact with the aggregated mass of grains of superhard material or in indirect contact therewith, the ceramic layer being spaced from the grains by an interlayer of material when present, the ceramic layer having a surface with surface topology, the surface topology imprinting a pattern in the aggregated mass of grains of superhard material complementary to the surface topology, the ceramic material and the material of the interlayer being such that they do not react chemically with the superhard material and/or a sinter catalyst material for the grains of superhard material. The aggregated mass of grains of superhard material and ceramic layer are subjected to a pressure of greater than 5.