Preparation of WC–xVC composite powders and the effect of high content VC on microstructure and mechanical properties of WC–Co based cemented carbides

The WC–xVC composite powders were synthesized by two-step carbothermal reduction process, and the WC–Co–VC cemented carbides with different mass fraction of Co (6% and 10%) were prepared by vacuum sintering method using the WC–xVC composite powders as the raw materials. The effect of sintering temperature (1420 ℃, 1440 ℃, and 1460 ℃) on the densification process of the cemented carbides was studied. Meanwhile, the effects of Co and VC content on the grain size, hardness, and fracture toughness of the WC samples were investigated. The experimental results show that the relative density of the alloys increases with the increase of sintering temperature. When the sintering temperature is 1460 ℃, the relative density of each sample is greater than 98.5%. With the increase of VC addition amount, the average grain size of WC decreases, which leads to the increase of hardness and the decrease of fracture toughness. When the VC mass fraction is 6%, the hardness of the WC–6Co cemented carbides and the WC–10Co cemented carbides reaches the maximum as HV₃₀ 1941 and HV₃₀ 1838, respectively. In addition, under the certain condition of sintering temperature and VC content, the fracture toughness of the samples increases with the increase of Co content, and the hardness of the samples decreases.