Abstract: Spinodally-decomposing mixed crystals of zirconium and titanium carbides, possibly including carbonitrides and optionally including one or more carbides of metals of Group Vb of the Periodic Table of the Elements, are used in making sintered hardmetals based on tungsten carbide. One or more iron group metals or alloys, preferably cobalt or a nickel alloy, is or are used as a binder. The sintered hardmetals are made by a 2-stage process, mixed crystal material comprising zirconium and titanium carbides being formed in the first stage and being combined with the binder and tungsten carbide in the second stage. Process variations which encourage spinodal decomposition of the mixed crystal material are also disclosed.

Abstract: Mixed crystals of zirconium and hafnium carbides, possibly including the carbonitrides, are used in place of tantalum carbide in sintered hard metals. The new products contain one or more hard metals of Groups IV to VI of the Periodic Table of the Elements other than the mixed crystals, in particular, titanium and tungsten carbides, possibly with carbides of vanadium, niobium, molybdenum or chromium, and one or more iron group metals or alloys, preferably cobalt, is or are used as a binder. The sintered hard metals are made essentially by a 2-stage process, mixed crystal material comprising zirconium and hafnium carbides being formed in the first stage and being combined with the binder in the second stage, the one or more other hard metals of Groups IV to VI being incorporated in one or both stages. Any tendency to microporosity, shown particularly by products having a nitrogen content, is avoided by hot isostatic pressing.