Hybrid Monte Carlo/molecular dynamics simulation of a refractory metal high entropy alloy

TL;DR

This study uses a hybrid Monte Carlo and molecular dynamics approach to investigate temperature-dependent chemical ordering in a refractory metal high entropy alloy, revealing ordering at low temperatures that diminishes with heat.

Contribution

It introduces a combined simulation method to analyze chemical order in high entropy alloys, providing insights into temperature effects on atomic arrangements.

Findings

Cesium-chloride ordering at 300K between specific metal sites

Order diminishes at higher temperatures

First principles calculations suggest potential low-temperature phases

Abstract

The high entropy alloy containing refractory metals Mo-Nb-Ta-W has a body centered cubic structure, which is not surprising given the complete mutual solubility in BCC solid solutions of all pairs of the constituent elements. However, first principles total energy calculations for the binaries reveal a set of distinct energy minimizing structures implying the likelihood of chemically ordered low temperature phases. We apply a hybrid Monte Carlo and molecular dynamics method to evaluate the temperature-dependent chemical order. At 300K a cesium-chloride ordering emerges between mixed (Nb,Ta) sites and mixed (Mo,W) sites. This order is lost at elevated temperatures.