Effect of Mo on the thermal stability of γ′ precipitate in Inconel 740 alloy

The effect of Mo on gamma prime (γ′) coarsening kinetics of Ni-25Cr-20Co-1.8Ti-0.9Al-2Nb-0.03C-xMo (x = 0.5, 3, 6 wt.%) alloys was investigated with respect to the activation energy for γ′ precipitate coarsening. The coarsening rates were measured at temperatures of 760 °C, 780 °C, and 810 °C up to 500 h. Coarsening rate decreased with increasing Mo, and the activation energies for coarsening were determined to be 245 kJ/mol, 261 kJ/mol, and 278 kJ/mol for 0.5 wt.% Mo, 3 wt.% Mo, and 6 wt.% Mo, respectively.