A general statistical framework for vacancy and self-interstitial properties in concentrated multicomponent solids

TL;DR

This paper extends a statistical framework to predict the thermodynamics of vacancies and self-interstitials in complex alloys, providing insights into defect stabilization and symmetry-breaking effects relevant for materials in clean energy applications.

Contribution

It introduces a generalized statistical model for defect thermodynamics in multicomponent alloys, including predictions of defect stabilization and symmetry-breaking phenomena.

Findings

Certain self-interstitial dumbbells are stabilized by Cr in Fe alloys.

High solute concentrations cause distortion and misalignment of self-interstitials.

The framework accurately predicts defect formation energies in complex alloys.

Abstract

A rigorous understanding of the thermodynamic properties of point defects, namely vacancies and self-interstitials, is crucial for the discovery and screening of structural materials in clean energy applications. In this work, we extend a previously-developed statistical framework for predicting the thermodynamics of single-site impurities to further predict the thermodynamics of self-interstitial dumbbells in an arbitrarily complex alloy. We then apply this extended framework to compute effective formation energies in fully disordered Fe-Cr and Cu-Ni alloys. Notably, we predict that some self-interstitial dumbbell types that are high-energy in pure Fe become stabilized by Cr. We additionally describe a symmetry-breaking effect, wherein high solute concentrations distort the defect free energy surface, yielding misaligned self-interstitials.