Effect of varying carbon content on microstructural evolution and mechanical properties of (TiZrHf)Cx–Ni cermets

A series of (TiZrHf)C_x–10 wt.% Ni multi-component carbide-based cermets with varying carbon contents was successfully fabricated by spark plasma sintering under temperatures of 1450°C and 1550°C utilizing carbide composite powders prepared via carbothermal reduction reaction at 1600°C. The effects of carbon content on the phase composition, microstructural evolution, and mechanical properties of (TiZrHf)C_x–Ni cermets were systematically investigated. A certain amount of carbon vacancies is beneficial to promote the densification process and solid solution formation. With the decline in carbon content, the average grain size gradually increases, while TiC segregation tends to diminish until a single-phase hard phase is achieved. Both the Vickers hardness and fracture toughness exhibit a similar declining trend with decreasing carbon contents. The (TiZrHf)C–10 wt.% Ni cermet demonstrates the best overall performance, achieving the Vickers hardness and fracture toughness values of 17.5 GPa and 7.9 MPa·m^1/2, respectively.