Loading rate sensitivity of nickel-based single crystal superalloys characterized by nanoindentation

Nickel-based single crystal superalloys (NBSX) are extensively applied in advanced aero-engine and gas turbine blades. In this work, a new method is proposed to investigate the sensitivity of loading rate on the mechanical behavior of NBSX along the [0 0 1] direction by nanoindentation tests with different indenters. Based on the reduced modulus, the load-depth curves of a pyramidal indenter are corrected to eliminate the influence of indentation size effect and pile-up or sink-in. Results show that the hardness of NBSX increases with the loading rate, indicating the loading rate hardening effect. In the process of indentation, there is a certain softening effect. With the increase of loading rate, the creep displacement/strain rate of NBSX increases. In contrast to creep displacement, the creep strain rate declines quickly at the initial holding stage and then decreases slowly to a steady-state creep stage.