Oxidation-induced recrystallization and damage mechanism of a Ni-based single-crystal superalloy during creep

The creep tests for Ni-based single-crystal superalloy are carried out under 980 °C, and the microstructure at the crack tip is characterized at micro- and nano- scales. Numerous γ’ phase dissolution, nucleation and growth of fine grains are observed near the crack. In addition, γ’ phase did not effectively hinder the nucleation and growth of recrystallization grains at the oxidation-affected zone. Instead, recrystallization promoted the degradation of the γ’ phase to dissolve along the recrystallized grain boundaries. Combining the sub-grain boundary growth model proposed by Winning et al. and the discontinuous recrystallization model suggested by D.G. Cram, a recrystallization and oxidative damage model for Ni-based single-crystal superalloy is proposed.