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, nickel and/or chromium. 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, nickel and/or chromium, 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.