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

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.

Figures (7)

• Figure 1: Example possible microstates in $\text{Fe}_{1-x}\text{Cr}_x$ visualized with Open Visualization Tool (OVITO) stukowski2009visualization.
• Figure 2: Effective formation energies for each SIA dumbbell type in $\text{Fe}_{1-x}\text{Cr}_x$ as a function of composition and temperature.
• Figure 3: Effective formation energies for vacancies in $\text{Fe}_{1-x}\text{Cr}_x$ as a function of composition and temperature.
• Figure 4: Effective formation energies for each SIA dumbbell type in $\text{Cu}_{1-x}\text{Ni}_x$ as a function of composition and temperature.
• Figure 5: Effective formation energies for vacancies in $\text{Cu}_{1-x}\text{Ni}_x$ as a function of composition and temperature.