A Simple Phenomenological Model to Describe Stability of Homogeneous Solid Solutions in High Entropy Alloys from Metallic Bonding Potential

Abstract

A simple model based on the potential parameters used to describe metallic bonding is extended to solid solu- tions. A figure of merit (an effective temperature, Teff ) is proposed using a simple average over the potential coefficients to discern whether a homogeneous solid solution is expected to be stable or not in high entropy alloy compositions. Teff is calculated as the ratio between the solid solution excess in bonding energy over the average mixture divided by the configurational entropy. Application to the sexinary AlCrCuFeNiCo system stablishes a stability threshold for Teff < 500 K. The model can successfully describe both the deviations from Vegard’s law observed in binary alloys and the differences in this parameter between B2 ordered and bcc disordered phases considering average potential coefficients over the different possible atomic couples.