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Ultrafine WC–Co–VC cemented carbides are used extensively in a variety of industrial environments due to their excellent mechanical properties and outstanding wear resistance. Co content affects the service performance of the cemented carbides. In the present study, the influences of Co content on microstructure, physical, and mechanical properties were investigated systematically. Ultrafine WC–Co–VC cemented carbides with Co content varying from 4 wt% and 7 wt% and assistance of VC (0.35 wt%) as inhibitor of WC grain growth were prepared. The physical and mechanical properties were tested and the microstructure characteristics were observed by optical microscope (OM) and scanning electron microscopy (SEM). From the results, it is found that with Co content increasing, both the cobalt magnetism and bending strength increase, while the coercive force, Rockwell hardness, density, and abrasive wear resistance decrease. In addition, the OM and SEM results show that the increase of Co content in WC–Co–VC cemented carbides tends to reduce the quantity and size of micro-pores, and make the fracture mode change from brittle fracture to ductile fracture. [ABSTRACT FROM AUTHOR]

The initial WC grain-size distribution, as one of the most important factors influencing the properties of alloys, has been focused on for a long time in some fields other than cemented carbides. In the present work, five groups of WC-6Ni cemented carbides were prepared and the effect of initial WC grain-size distribution on the microstructure and properties of the hard alloys was studied. The results indicate that initial WC grain-size distribution has significant influence on the microstructure and properties of WC-6Ni cemented carbides, except density. When the mass ratio of coarse-WC and fine-WC is 7:3, WC-6Ni cemented carbide samples with initial WC grain-size distribution of WC-1(4.8 μm) and WC-4(0.7 μm) show a relatively good combination properties, while the cemented carbide samples with WC-5(0.4 μm) as the fine-WC component exhibit higher values on some properties, mainly hardness and immersion corrosion resistance in acid and alkali. [ABSTRACT FROM AUTHOR]