Influence of γʹ volume fraction on creep of Ni-based superalloy through phase-field simulations

γʹ volume fraction (f_v) plays a critical role in the mechanical properties of Ni-based single-crystal superalloys. A creep phase-field model is utilized to simulate the microstructure evolution and creep performance during creep under different f_v conditions. The influence mechanism of f_v on creep properties is investigated based on the analysis of evolutions of internal stress and strain fields. As f_v increases, the morphology of γʹ rafts changes from discontinuous to continuous, while the morphological change of γ channels is opposite, the inclination of γ channels from the [010] direction to 〈011〉 directions during tertiary creep first decreases and then increases, the creep life first increases and then decreases, and the main distribution of creep damage shifts from γʹ to γʹ/γ interfaces and γ channels. The longest creep life under f_v of 0.65 can be attributed to the stable γʹ raft structure, the lowest stress and strain in γ channels, and the slowest damage accumulation.