Effects of Dwell Time on Thermo-Mechanical Fatigue Behavior in a Single-Crystal Ni-Based Superalloy

The microstructural effect on the dwell time of the TMF test, which can describe a part of the gas turbine, was studied. In out-of-phase (OP) with dwell time on a single-crystal Ni-based superalloy, the TMF life was reduced by 61.5% compared to without dwell times. Due to the introduction of dwell time, the deformation behavior transitioned from hardening to softening. During exposure at maximum temperature, stress relaxation was occurred, which meant releasing the dislocation tangle. However, the dwell time led to the topologically close-packed (TCP) phase formation and growth. In conditions with the dwell time, TCP phase particles were increased by 241% and coarsened. Also, mechanical twins, which had resistance to crack propagation, were reduced. Therefore, the introduction of dwell time led to the promotion of cracks and the loss of resistance to crack propagation.