Stability prediction of AlCoCrFeMo0.05Ni2 high entropy alloy by Kinetic Monte Carlo method

Abstract

High entropy alloys (HEAs) are most likely to be the next-generation superalloy. However, their development are often limited by the instability of a solid solution in the alloys especially for high entropy superalloys (HESAs). Due to the complex and large systems of HEAs and the lack of HEAs databases, the stability prediction of a solid solution in a HEA becomes a huge challenge. Here, Kinetic Monte Carlo (KMC) simulation was used to investigate the metastability in AlCoCrFeMo0.05Ni2 HEA, in which atomic parameters such as interatomic and interatom-vacancy interaction potential were adopted to study the atomic diffusion behavior during annealing by simulating vacancy migration. For the first time, the phase separation behavior in a FCC solid solution of the AlCoCrFeMo0.05Ni2 HEA was predicted by the KMC method, in which Al atoms were found to occupy preferentially vacancies and eventually formed the (Ni, Al)-rich phase during annealing at 973 K. And the vacancies, captured by the (Ni, Al)-rich phase, promoted the growth and transition of the phase from FCC to BCC structure.