Cermet microstructure and mechanical properties: Influence of metallic additives (Mo, Si, Ti, V) in WC-5wt%co composites fabricated via spark plasma sintering

Abstract

This study examined the impact of metallic additives (Mo, Si, Ti, and V) on the microstructure and mechanical properties of WC-5wt%Co cermets prepared via spark plasma sintering. Four different batches of WC-5 wt% Co each supplemented with 5 wt% metallic additive powders were mixed through a high-energy mixing/short-time process to obtain a uniform distribution of the binder phase and each of the additives. Spark plasma sintering was primarily conducted at 1350 °C for all the prepared samples, but the WC-Co-Si sample required a lower temperature of 1200 °C due to binder phase melting. XRD analysis revealed WC as the dominant phase, with additional carbide compounds detected, except in the Mo-doped sample, which formed Co₆Mo₆C. The Ti-doped specimen exhibited the best mechanical properties, including a bending strength of 1078 MPa, Vickers hardness of 2547, and fracture toughness of 11.96 MPa·m^1/2, attributed to solid solution formation between WC and TiC. The study highlights the role of additive-induced reactions in enhancing mechanical properties and controlling grain growth.