Spark plasma sintering of WC-VC0.5 composites with exceptional mechanical properties and high-temperature performance

Abstract

WC-based composites, especially WC-Co, are generally considered representative of cermets with widespread commercial applications. The remarkable toughening enhancement is achieved in WC-Co cermets, however, the incorporation of metallic binders invariably results in a serious deterioration of both hardness and thermal stability. Here we synthesized WC-VC0.5 composites with exceptional combination of high hardness and fracture toughness and high-temperature hardness. Conspicuously, the composite of WC with 5 wt.% VC0.5 sintered at 1750 °C shows superior comprehensive mechanical properties of high microhardness of 26.2 ± 0.5 GPa and toughness of 9.2 ± 0.2 MPa·m1/2. WC-VC0.5 composites possess excellent high-temperature hardness, and the hardness of WC-5 wt.% VC0.5 at 700 °C is still over 20 GPa. These excellent properties are attributed to high densification in addition to high-dose stacking faults caused by vacancy defects and twinned structure. Our study may offer a promising pathway towards the design and synthesis of next-generation advanced composites for applications in demanding industrial environments, especially high-temperature applications.