Microstructure and mechanical properties of WC-CoCrFeNi cemented carbides fabricated by spark plasma sintering process

WC–CoCrFeNi cemented carbides were fabricated using high-energy ball milling and spark plasma sintering to explore the use of CoCrFeNi as a low-cobalt binder for WC-based cemented carbides. The effects of sintering temperature (1200 °C–1350 °C) and binder content (5 wt.–20 wt%) on phase constitution, microstructure, densification, hardness, fracture toughness, and transverse rupture strength (TRS) were systematically examined. Increasing the sintering temperature improved densification but also promoted WC grain growth, resulting in reduced hardness and a non-monotonic variation in fracture toughness. Increasing the CoCrFeNi content refined WC grains and reduced porosity; however, excessive binder addition (20 wt%) reduced hardness and TRS because an increased soft-phase fraction and weakened hard-phase skeleton offset the benefits of further densification. For the composite containing 15 wt% CoCrFeNi binder, 1300 °C provided the most favorable property balance within the investigated temperature range. Among the compositions evaluated at 1300 °C, the specimen containing 15 wt% CoCrFeNi exhibited the best overall performance, with a hardness of 1883 HV 30 , a fracture toughness of 12.6 MPa·m 1/2 , and a TRS of 1416 MPa. The improved property balance is attributed to enhanced densification, restrained WC coarsening, reduced effective defect size, and more effective crack deflection. These results indicate that CoCrFeNi represents a promising low-cobalt binder design strategy for WC-based cemented carbides.