Patent ID: 7939013

Claim:
Method of making a coated cemented carbide comprising WC, a binder phase based on Co, Ni or Fe and a gamma phase with a surface zone essentially free of gamma phase by powder metallurgical methods known in the art wherein the powders forming the gamma phase are added as a cubic mixed carbide (Ti,Nb,Ta,W)C alloyed with an amount of WC given by the mol fraction of WC, x WC , such that the ratio between x WC and the equilibrium gamma phase WC content at the sintering temperature expressed as mol fraction WC, xe WC , f WC =x WC /xe WC is from about 0.6 to about 1.0, where the WC solubility at the sintering temperature is given by the relation xe WC =(0.383 *x TiC +0.117 *x NbC +0.136 *x TaC )/( x TiC +x NbC +x TaC ).