(Ti,W)C–Ni cermet prepared by high-energy ball milling and subsequent carbothermal reduction of TiO2–Ti–WO3–C mixture

A single-phase (Ti,W)C solid solution was prepared by high-energy ball milling of TiO2–Ti–WO3–C powder mixtures with various TiO2/Ti ratios and subsequent carbothermal reduction. Thermodynamic calculations suggest that the reaction pathways would follow the sequences WO3→WC, TiO2→Ti2O3, Ti(CO)→TiC, Ti2O3→TiC, and TiC+WC→(Ti,W)C. The reaction pathways were substantiated by measuring CO gas evolution and heat flow using QMS and DSC, respectively. The 80(Ti,W)C–20Ni powders were sintered in vacuum at 1510 °C and their mechanical properties were evaluated. The toughness values of (Ti,W)C–Ni cermet were significantly higher than those of TiC–Ni cermet owing to the alloying effect of W in TiC. The composition of raw powder mixture also affected the mechanical properties of (Ti,W)C–Ni after sintering. The toughness was improved when TiO2/Ti ratio was 2 in the raw powder mixture than when pure Ti or TiO2 was used. The enhanced toughness is attributed to larger (Ti,W)C grain size.