Predicting the thermal expansion of body-centred cubic (BCC) high entropy alloys in the Mo-Nb-Ta-Ti-W system

Abstract

In this study, the thermal expansion behaviour of equiatomic alloys in the Mo-Nb-Ta-Ti-W system is studied to provide a predictive method to assess the behaviour of this and other high entropy alloy systems. The simulations used are based on first principles density functional perturbation theory and the quasi-harmonic approximation. Calculations have been used to predict the stability and phonon properties of increasingly complex alloys in the Mo-Nb-Ta-Ti-W system and their thermal expansion coefficients have been predicted. These are benchmarked against rule-of-mixtures predictions and experimental observations, where available. We have shown that atomic-scale modelling techniques can be used to reliably predict the thermal expansion of a range of body-centred cubic high entropy alloys and concentrated solid solutions.