Atomic scale modeling of structural phase transformations in AlCrFeMnMo high-entropy alloys during thermal treatments

Abstract

The objective of this work is to provide an overview of the evolution of phase transformations in AlCrFeMnMo high-entropy alloys (HEAs), a recently proposed family showing great promises in metallurgical industry for coating applications. We perform Monte-Carlo simulations based on ab initio energy parameters, to analyze the order/disorder transition and the phase separation process from the high-temperature A2 single phase. The reliability of the atomic-scale approach, already known to work on AlCoCrFeNi, is first confirmed on AlCrFeMnNi, the presence of A2-(Cr,Fe,Mn) and B2-(Al,Ni) being in good agreement with previous experimental studies. However, simulations of equimolar AlCrFeMnMo show that the A2 solid solution should transform into two B2 phases at ambient temperature, instead of a couple of A2 phases observed experimentally. The reasons for this discrepancy are discussed. Increasing iron and decreasing molybdenum contents in AlCrFeMnMo favors ordering for chromium and phase change for aluminum, without changing the conclusion on A2 / B2 competition previously drawn from the equimolar case.