Dynamic heterogeneity of atomic transport in a body-centered cubic WTaVCr non-equiatomic high-entropy alloy

Abstract

Compared to face-centered cubic (fcc) high-entropy alloys (HEAs), body-centered cubic (bcc) HEAs generally possess larger lattice distortion, resulting in distinct point defect properties. In this work, molecular dynamics (MD) simulations and molecular statics (MS) calculations were performed to study the dynamic heterogeneity in a bcc W40Ta35V10Cr15 non-equiatomic HEA with large lattice distortion. Defect energies in W40Ta35V10Cr15 HEA show a strong preference for a specific element and possess large energy spreads, resulting in dynamic heterogeneity of atomic transport in the process of defect diffusion and evolution. V and Cr interstitials exhibit higher occurrence probability and faster diffusion compared to W and Ta interstitials. Such diffusion heterogeneity brings about high recombination probabilities of W and Ta interstitials and large fractions of V and Cr in surviving interstitials during displacement cascades. The binding ability of interstitials correlates with the magnitude of interstitial formation energies. The smaller the interstitial formation energies, the weaker the binding abilities. A large number of surviving V and Cr interstitials with smaller interstitial formation energies exhibit weak binding abilities and discrete distribution. Our findings suggest that the dynamic heterogeneity in W40Ta35V10Cr15 HEA with large lattice distortion may be the underlying mechanism of outstanding irradiation resistance.