Point defects and their properties in the Fe$_{20}$Ni$_{20}$Cr$_{20}$Co$_{20}$Cu$_{20}$ high-entropy alloy

The characteristics of interstitial atoms and vacancies in the Fe$_{20}$Ni$_{20}$Cr$_{20}$Co$_{20}$Cu$_{20}$ high-entropy alloy have been determined by the molecular dynamics and statics methods. The effect of these defects on elastic moduli has been analyzed. It has been found that interstitial atoms are stable only in the form of dumbbells responsible for a significant diaelastic effect (decrease in the shear modulus). As compared to vacancies, an increase in the concentration of interstitial dumbbells much more rapidly reduces the shear modulus with an increase in the volume. Furthermore, interstitial dumbbells are responsible for the appearance of specific high- and low-frequency modes in the spectrum of the vibrational density of states. The latter modes are related to the observed diaelastic effect. The evolution of the diaelastic effect and vibrational spectrum during the transition of the system to a noncrystalline state has been studied.