Properties of New WC-Co Base Hardmetal Prepared From Co_xW_yC_z Complex Carbide Powder Instead of WC+Co Mixed powder

摘要

In the previous papers, we have already reported that WC-Co base hardmetal (W+Graphite+Co alloy) prepared from W+Graphite mixed powder instead of conventional WC powder has a large amount of plate-like triangular prismatic WC grains with highly unidirectional orientation, and that it shows higher fracture toughness and transverse-rupture strength than the conventional hardmetal at an identical hardness. In this study, we prepared new WC-Co base hardmetal by using Co_2W_4C and Co_3W_9C_4 complex carbide powders as the main starting materials. It was confirmed that WC grains in the hardmetals are also plate-like triangular prismatic, but are not oriented, i.e., isotropic, differing from W+ Graphite+Co alloy. The fracture toughness, however, was higher by 10～15% than the conventional alloy at an identical hardness, although the transverse-rupture strength was nearly the same as that of the conventional alloy.