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

Molecular dynamics simulations of 50 Fe grain boundaries were used to understand their interaction with vacancies and self-interstitial atoms, which is important for designing radiation-resistant polycrystalline materials. Site-to-site variation of formation energies within the boundary 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.

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► Binding energies for grain boundary sites from 50 <100> symmetric tilt grain boundaries were calculated for vacancies and self-interstitial atoms in Fe.
► Self-interstitial atoms have a larger driving force for binding to grain boundaries than vacancies.