Structure and properties of bulk nano-structured WC–CO alloy by mechanical alloying

Abstract

Mixtures of elemental powders of nominal composition WC–6wt%Co and WC–6wt%Co–1wt%VC were prepared using 99.5% purity tungsten, graphite, cobalt and vanadium powders with particle sizes smaller than 75 μm. Mechanical alloying (MA) was performed in a QM-1 planetary ball mill. The structural evolution and the crystallite size changes of the powders during MA were monitored by X-ray diffraction. The results show that cemented carbides of WC–Co powder with crystalline sizes of about 10 nm were directly synthesized from elemental powders by mechanical alloying. Cold compacting was carried out at a pressure of 800 MPa using a manual uniaxial press with carbide insert dies. The hardness and sintered density of sintered samples were measured. The effects of small VC additions on the grain size, density and hardness of sintered samples were also investigated.