Polycrystalline diamond constructions & methods of making same

A polycrystalline diamond construction has a body of polycrystalline diamond(PCD) material bonded at an interface to a cemented carbide substrate. The cemented carbide substrate comprises 70-95 % by weight of tungsten carbide particles bonded together by a binder material which comprises cobalt. The cemented carbide further comprises 0.1-3 % by volume of free carbon, SP2-hybridised carbon or SP3-hybridised carbon (e.g. diamond) with a largest average dimension of less than 40 microns. The construction can be made by milling tungsten carbide powder, binder which comprises cobalt, and graphite or amorphous carbon in an amount where the carbon equivalent content to the milled tungsten carbide powder is more than 6.2 % by weight. The milled powder is compacted and sintered, followed by adding a layer of diamond particles and then sintering a temperature and pressure where the diamond particles corm a PCD material.