Deformation behavior and yield strength prediction of [112] oriented NbMoTaW refractory high entropy alloy nanowires

Abstract

Refractory high entropy alloys (RHEAs) have garnered widespread attention due to their potential applications at extremely high temperatures. However, accurately predicting the mechanical properties of these materials is challenging due to the complex slip systems in body-centered cubic (BCC) metals. In this work, the tensile behaviors of NbMoTaW RHEA single crystalline nanowires with various radii under tensile deformation were investigated using molecular dynamics simulations, focusing on their deformation behavior, mechanical response, and size-dependent effects. The results revealed a transition in yield stress from the Hall–Petch relation to the inverse Hall–Petch relation with the decrease of the nanowire radius. The primary deformation mechanism observed was the nucleation and glide of dislocation from the surface. A thermal activation-based theoretical model was developed for determining the yield stress, incorporating stacking fault energy and surface energy as pivotal parameters. This model could effectively predict the yield stress of the RHEA in the inverse Hall–Petch stage and exhibit significant potential in predicting the mechanical properties of other BCC metals.