Performance enhancement of ultra-coarse cemented carbide by boride additives

Abstract The ultra-coarse WC-Co cemented carbides with additives of WB and WCoB have been developed. The effects of WB and WCoB additions on the microstructure and mechanical properties of the prepared cemented carbides were studied in detail. It was found that the additions have slight influence on the mean grain size of the cemented carbides. The addition of WB caused an inhomogeneous distribution of its reaction product WCoB in the cemented carbide. In contrast, direct addition of WCoB avoided this problem, leading to its relatively homogeneous distribution at the WC/WC and WC/Co interfaces. As a result, both the hardness and transverse rupture strength were enhanced in the cemented carbide with WCoB additive. The main reason for such a behavior is that the WCoB phase, with intrinsic high hardness, can form the WCoB/WC and WCoB/Co interfaces with high bonding strength, which is beneficial to both the toughness and fracture strength of the cemented carbide.