Effect of Temperature Fluctuations on the Creep Properties of Nickel‐Based Single‐Crystal Superalloys at 1200°C

Advanced aero‐engines with thrust‐to‐weight ratios of 15–20 require turbine blade materials based on single‐crystal superalloys that can withstand temperatures up to 1200°C. However, at 1200°C, temperature fluctuations often prevent single‐crystal superalloys from achieving stable operation. This leads to substantial dissolution of the γ′ strengthening phase, causing the creep life to be shorter than the steady‐state creep life. In this study, the effect of temperature fluctuations (1200°C ∼ 1220°C) on the creep properties of Ni‐based single‐crystal superalloy was revealed. The results indicate that the thermal cycling creep life of the alloy shows a strong negative correlation with cycle frequency. Notably, the creep life of the sample with the highest thermally cycled frequency is lower than that of the isothermal creep sample at an overheating temperature of 1220°C. The deterioration of creep properties induced by thermal cycling is not solely due to microstructural degradation. Thermal cycling induces repeated γ′ dissolution‐reprecipitation, immobilizing dislocations to cause premature γ′ cutting and promoting γ matrix plastic accumulation to accelerate superalloy deformation. This study establishes a semi‐quantitative foundation for evaluating the plastic accumulation threshold induced by thermal cycling and creep acceleration, providing a novel technical approach for the life prediction of turbine blades under thermally cycled conditions.