Enhanced mechanical properties and thermal stability of hot-rolled Mo-0.5%ZrC alloy

Mo-0.5 wt%ZrC alloy plate with enhanced mechanical properties and thermal stability was manufactured by powder metallurgy and hot rolling. The as-rolled Mo-0.5%ZrC plate shows an ultimate tensile strength (UTS) of 725 MPa and a total elongation (TE) of 24.1% at room temperature. After annealing at 1300 °C, the UTS of Mo-0.5%ZrC alloy decreased to 676 MPa while the TE increased to 32.8%. After 1600 °C annealing, the UTS of Mo-0.5%ZrC alloy is 507 MPa and the TE increased significantly to 56.4%. Additionally, Mo-0.5%ZrC alloy exhibits a high recrystallization start temperature of about 1300 °C. The addition of nanoscale ZrC particles can enhance the strength and high temperature stability by pining dislocations and grain boundaries. Meanwhile, ZrC nanoparticles can also react with the impurity oxygen to form Zr–C–O or ZrO2 particles, and thus alleviate the oxygen embrittlement of Mo alloy. However, the oxide particles tend to grow into larger particles at high temperatures, leading to decreased number density of dispersoids and lower dispersion-strengthening effect.