A self-contained algorithm for determination of solid-liquid equilibria in an alloy system

TL;DR

This paper presents a comprehensive, self-contained computational method to evaluate solid-liquid phase equilibria in alloy systems, combining thermodynamic integration, Gibbs-Duhem integration, and alchemical paths, demonstrated on the Al-Sm system.

Contribution

The paper introduces a novel, integrated algorithm for calculating free energies and phase equilibria in alloys, including nucleation and melting properties.

Findings

Calculated free energies for Al-Sm phases

Determined melting curves for fcc-Al and Al3Sm

Analyzed nucleation driving forces in Al-Sm liquid

Abstract

We describe a self-contained procedure to evaluate the free energy of liquid and solid phases of an alloy system. The free energy of a single-element solid phase is calculated with thermodynamic integration using the Einstein crystal as the reference system. Then, free energy difference between the solid and liquid phases is calculated by Gibbs-Duhem integration. The central part of our method is the construction of a reversible alchemical path connecting a pure liquid and a liquid alloy to calculate the mixing enthalpy and entropy. We have applied the method to calculate the free energy of solid and liquid phases in the Al-Sm system. The driving force for fcc-Al nucleation in Al-Sm liquid and the melting curve for fcc-Al and Al3Sm are also calculated.