Defect energetics in an high-entropy alloy fcc CoCrFeMnNi

Abstract

High-entropy alloys (HEAs) are promising candidate materials in nuclear applications owing to their excellent mechanical properties and improved resistance to radiation damage. Defect formation energy in HEAs is directly dependent on the choice of chemical potential, and different chemical potentials can contribute to the discrepancies in the statistical spread. Herein, first-principles calculations were performed to investigate the defect energetics in a fcc CoCrFeMnNi HEA based on chemical potentials, which are back-derived in a self-consistent manner. Chemical potentials are more accurate and precise without additional computational cost and associated uncertainty. The computational results show that defect formation energy is strongly dependent on the local atomic environment and weakly dependent on the chemical composition. Moreover, vacancies prefer the Cr- and Mn-deficient as well as Ni-rich local atomic environment. There is a distinct relationship between the interstitial-specific formation energy and the number of X atoms in 1-NN, while, irrespective of interstitial species, there is no obvious trend in the dependence of the interstitial formation energy and the local atomic environment. The average vacancy migration energies follow the order: Cr < Fe < Mn < Ni < Co, which is lower than that in pure Ni, and the Fe and Cr atoms in 1-NN around vacancies prefer to exchange with vacancies to help vacancy migration. Furthermore, the local atomic environment of the Mn and Ni atoms of the chemical species that exchanges with vacancies suppresses vacancy migration and that of the Co and Fe atoms facilitates vacancy migration. The results of this work can contribute to understanding the enhanced irradiation resistance of HEAs and may provide a new paradigm for the design of advanced radiation-tolerant HEAs.