SEGREGATION OF VANADIUM AT THE WC CO INTERFACE IN VC-DOPED WC-CO/

Morphology of carbide grain in WC-12 wt.% Co-0.5 wt.% VC was examined by HREM and EDS with a special interest in the segregation of V at the WC/Co interfaces. A small addition of VC in WC-Co is effective to sup press the grain growth of carbide grains. HREM observation revealed th at the WC/Co interfaces are faceted and consist of mainly two kinds of habit planes, (10 (1) over bar 0) and (0001), respectively. EDS analy ses clearly showed the segregation of doped V along the interfaces. In addition, the concentration of segregated V is higher at the (0001) t ype habit plane than (10 (1) over bar 0) one. The retardation of the g rain growth of carbide grains in the VC-doped WC-Co is closely related to the formation of the faceted WC/Co interface.