Electronic structure, phase stability, and transport properties of the AlTiVCr lightweight high-entropy alloy: A computational study

Abstract

We investigate the thermodynamics and phase stability of the AlTiVCr lightweight high-entropy alloy using a combination of ab initio electronic structure calculations, a concentration wave analysis, and atomistic Monte Carlo simulations. In alignment both with experimental data and with results obtained using other computational approaches, we predict a B2 (CsCl) chemical ordering emerging in this alloy at comparatively high temperatures, which is driven by Al and Ti moving to separate sublattices, while V and Cr express weaker site preferences. The impact of this B2 chemical ordering on the electronic transport properties of the alloy is investigated within a Kubo–Greenwood linear response framework and it is found that, counter-intuitively, the alloy’s residual resistivity increases as the material transitions from the A2 (disordered bcc) phase to our predicted B2 (partially) ordered structure. This is understood to result primarily from a reduction in the density of electronic states at the Fermi level induced by the chemical ordering. These results give fresh insight into the atomic-scale structure and consequent physical properties of this well-studied, technologically relevant material.