Creep prediction model for nickel-based single-crystal superalloys considering precipitation of TCP phase

Abstract

The microstructure of nickel-based single-crystal (SC) superalloys has a pivotal influence on their creep properties. The addition of the Re element not only enhances the long-term creep properties of nickel-based SC superalloys, but also results in the formation of a topologically close-packed (TCP) phase which is a harmful and brittle hard phase. Here, high-temperature creep interruption tests of a nickel-based SC superalloy that contains 4.8 wt% Re were performed under various temperatures and stress conditions, and the evolution of microstructure during creep was observed by scanning electron microscopy (SEM). The volume fraction of the TCP phase was also extracted to explore the mechanism that controls the impacts of the TCP phase on the creep properties. According to the microstructure evolution mechanism, the influence of the TCP phase was attributed to the initial damage and critical shear stress of the material. A creep performance prediction model for nickel-based SC superalloys considering the precipitation of the TCP phase that is based on the crystal plasticity theory and a modified creep damage model was established. The simulation curves fit well with the experimental results and the errors between prediction creep life with test results are within 5%.