Nanoindentation creep behavior of high entropy superalloy with γ/γ′ microstructure under various loads and temperatures

High-entropy superalloys (HESAs) with a γ/γ′ microstructure similar to that of Ni-based single-crystal superalloys (NSCS) have emerged as promising candidates for high-temperature applications due to their high strength/density ratio and low cost. In this paper, the nanoindentation creep behaviors of HESA with the γ/γ′ microstructure under different loads and temperatures have been studied systematically. The HESA exhibits competitive creep resistance and structural stability as compared to NSCS. At low temperature and low load, the indentation features a shallow depth and a confined plastic deformation zone. However, at high temperature and high load, dislocations can progressively shear through multiple γ′ precipitates, resulting in an expanded plastic zone and a notable acceleration in the creep rate. With the increase of temperature and load, although the creep rate of this HESA increases gradually, it has higher stress exponent and superior creep resistance compared with most alloys. These new findings can provide guidance for the development of advanced HESAs and their engineering applications.