Polycrystalline cubic boron nitride composite material

A polycrystalline cubic boron nitride, PCBN, composite material consisting of:

• between 60 and 90 vol. % cubic boron nitride, cBN, particles and between 40 and 10 vol. % binder matrix material in which the cBN particles are dispersed, the cBN particles having an average grain size lying in the range 8 to 20 μm, the binder matrix material comprising between 90 and 99 wt. % an alloy of the refractory metals tungsten (W) and rhenium (Re) and which further comprises aluminium (Al) in a form other than as an oxide, the binder phase including an interface layer on the cBN grains, said interface layer comprising borides or nitrides of Al, characterised in that said aluminium (Al) is present in a quantity between 2 and 10 wt. % of the binder matrix material and the interface layer has an average thickness which lies in the range 100-250 nm.