A surrogate multiscale model for the design of high entropy alloys

Abstract

We propose a multi-scale physically-based model, for estimating the mechanical properties of a multicomponent alloy by statistically bridging the atomistic ($10^{-9}\text{–}10^{-7}\text{m}$), dislocation ($10^{-8}\text{–}10^{-6}\text{m}$) and macro ($10^{-6}\text{–}10^{-3}\text{m}$) length scales. We propose a temperature and strain-rate dependent dislocation theory model in which the velocity of dislocations is controlled by the average distance between barriers for dislocation glide i.e. the mean free path. The mean free path depends on the estimated distance between lattice distortions employing an atomistic model, and on the evolving immobile dislocation density as calculated by a modified Kocks–Mecking model, in which the mobility of dislocations is determined by the material stacking fault energy. The calculated flow curves and dislocation densities show good agreement with experimental data. The model relies on physically-based equations and parameters coherent with the literature, without empirical parameters, thus holding potential to speed up the pre-design phase of High Entropy Alloys for aerospace and nuclear components.