Anisothermal creep behavior at very high temperature of a Ni-based superalloy single crystal

Nickel-based superalloy single crystal specimens have been tested under anisothermal creep conditions using two different routes, both including an overheating stage. In the first route, the material is tested under creep conditions at 1050 °C, then submitted to an overheating regime at 1200 °C, and tested again at 1050 °C until fracture. In the second route, the specimens are cooled down to room temperature right after the overheating step, before creep testing at 1050 °C. The residual lives of the specimens tested using the first route are dramatically decreased compared to those obtained using the second. Surprisingly, in the last case, the longer the overheating stage, the longer the residual life. This behavior is related to the microstructural evolution occurring during the overheating stage.