Effects of (ZrHfNbTaTiMo)C addition on microstructure and mechanical properties of WC-10Co cemented carbides

The WC-10Co cemented carbides containing (ZrHfNbTaTiMo)C high-entropy carbide with satisfactory comprehensive mechanical properties were successfully manufactured by conventional vacuum sintering. The influences of (ZrHfNbTaTiMo)C contents (0, 0.5, 1, 5, 10 wt.%) on the densification degree, microstructure, grain size and mechanical properties were investigated. The results showed that the addition of (ZrHfNbTaTiMo)C deteriorated the wettability between Co and WC, leading to a decline in relative density. (ZrHfNbTaTiMo)C inhibited the growth of WC grains, and the average grain size of WC continued to decrease with the increase of (ZrHfNbTaTiMo)C content. After adding (ZrHfNbTaTiMo)C, the hardness and toughness rose first and then descended. When the content of (ZrHfNbTaTiMo)C was 1 wt.%, the hardness and toughness reached the maximum value of 16.77 GPa and 10.45 MPa·m1/2, respectively. Moreover, the structure was a dual-grain structure, with many high-aspect-ratio rectangular grains in the sintered samples added by 0.5 wt.% and 1 wt.% (ZrHfNbTaTiMo)C. This special structure not only enhanced the hardness, but also compensated the loss of toughness. After doping 0.5 wt.% CeO2, the hardness decreased slightly, while the toughness increased to 12.42%.