Energetic driving force for preferential binding of self-interstitial atoms to Fe grain boundaries over vacancies

TL;DR

This study uses molecular dynamics to analyze how grain boundaries in iron preferentially attract self-interstitial atoms over vacancies, revealing energetic preferences crucial for designing radiation-resistant materials.

Contribution

It provides detailed atomic-scale insights into the energetic interactions of vacancies and interstitials at Fe grain boundaries, highlighting the preferential binding of interstitials.

Findings

Interstitials have lower formation energies at grain boundaries than vacancies.

Self-interstitial atoms preferentially bind to grain boundary sites.

Data enables uncertainty quantification for microstructure evolution models.

Abstract

Molecular dynamics simulations of 50 Fe grain boundaries were used to understand their interaction with vacancies and self-interstitial atoms at all atomic positions within 20 Angstroms of the boundary, which is important for designing radiation-resistant polycrystalline materials. Site-to-site variation within the boundary of both vacancy and self-interstitial formation energies is substantial, with the majority of sites having lower formation energies than in the bulk. Comparing the vacancy and self-interstitial atom binding energies for each site shows that there is an energetic driving force for interstitials to preferentially bind to grain boundary sites over vacancies. Furthermore, these results provide a valuable dataset for quantifying uncertainty bounds for various grain boundary types at the nanoscale, which can be propagated to higher scale simulations of microstructure evolution.