Modeling the precipitation processes and the formation of hierarchical microstructures in a single crystal high entropy superalloy

Although superior high temperature tensile yield strength of high entropy superalloys (HESAs) arises from their hierarchical microstructure, the precipitation processes driving its formation remains unclear. In the present study, we analyze the kinetics of γ’ and γ precipitations by treating the concurrent nucleation, growth and coarsening using common computational thermodynamic and kinetic tools to simulate the microstructure genesis and evolution in HESA during thermal treatments. The ability of the simulations to reproduce the experimentally observed microstructure parameters is evaluated. Temperature-time-transformation (TTT) diagrams are calculated to serve as guidelines for further optimization of the hierarchical microstructure of HESAs.