Processing and characterization of spark plasma sintered TZM alloy

TZM is one of the most important molybdenum based alloys having a nominal composition of Mo–0.5 Ti–0.1 Zr–0.02 C (wt. %). This alloy possesses high temperature strength, high creep resistance, low coefficient of thermal expansion, and high thermal conductivity. TZM alloy processed contains TiC, ZrC and complex carbides which inhibit recrystallization at high temperatures improving its performances at harsh conditions. In this study pre-alloyed TZM powder was sintered by spark plasma sintering (SPS) at various sintering temperatures, holding times and pressures to investigate the effect of sintering conditions on densification, microstructure and hardness. In all cases, TiC and ZrC precipitations was observed throughout the microstructure. The average sizes of precipitates were measured as 7.5 and 3.5 μm for TiC and ZrC, respectively. The sample sintered at 1450 °C under 80 MPa for 150 s showed optimum properties as 95.5% of relative density, 8.5 ± 2 μm of average grain size, 2.04 ± 0.03 GPa of hardness, and 25.95 ± 3 MPa m^1/2fracture toughness.