Interplay of Carbon Content and Sintering Temperature on Microstructure and Mechanical Behavior in Ultrafine-Grained...

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.