As a crucial component of cemented carbide, the binder phase exerts a profound influence on its microstructure and mechanical properties. In this study, ultrafine-grained WC-10CoNiFe and WC-10Co cemented carbides, with grain sizes ranging from 0.25 to 0.4 μm, were fabricated via powder mixing, forming, and sintering processes utilizing 0.4 μm WC powder as the starting material. The effects of carbon content (5.44–5.50 wt%) and sintering temperatures (1410–1500 °C) on the grain organization and mechanical properties of these cemented carbides were systematically investigated. The results revealed that WC-10CoNiFe achieved its optimal mechanical properties at a carbon content of 5.46 wt% and a sintering temperature of 1450 °C, exhibiting a flexural strength of 2999 MPa and a hardness of 1765 HV. Likewise, WC-10Co attained its peak performance at a carbon content of 5.48 wt% and a sintering temperature of 1410 °C, with a flexural strength of 3598 MPa and a hardness of 1853 HV. Remarkably, the finer grain size of the WC-10CoNiFe alloy (0.261 µm), compared to that of WC-10Co (0.294 µm), can be ascribed to the suppression of the dissolution–reprecipitation process by the multi-principal-element alloy binder. This study demonstrated the synergistic regulation of microstructure and mechanical properties in ultrafine-grained cemented carbides through the incorporation of a multi-principal-element alloy binder. This innovative strategy not only effectively refines the grain size but also endows the alloy with exceptional mechanical properties, offering a valuable new perspective for the research and development of high-performance cemented carbides.

The development and research of physically superior multi-principal element alloy (MPEA) binders as cemented carbide binders is a hot topic. In this work, we fabricated a new type of MPEA binder-cemented carbide using the powder metallurgy method and investigated the effects of ball milling parameters and sintering temperature on the microstructure and mechanical properties of the cemented carbide. The results are compared with those of cobalt binder samples under the same conditions. The results show that the ball milling parameters for low-speed long ball milling time are superior to those for high-speed low ball milling time. Compared with the pure cobalt binder, MPEA binder-cemented carbide significantly slows down the growth of WC grains, improves the mechanical properties of cemented carbide, and achieves a combination of TRS of 2741.5 MPa and Rockwell hardness of 91.1 HRA. The multi-principal element alloy (MPEA) binder has the potential to become an excellent substitute for Co.