Efficient Annealing of Radiation Damage Near Grain Boundaries via Interstitial Emission

TLDR

Grain boundaries can act as sinks for radiation‑induced defects, yet the atomistic mechanisms underlying this enhanced tolerance remain poorly understood. Using three atomistic simulation methods spanning picoseconds to microseconds, we showed that interstitials load into grain boundaries and are subsequently emitted to annihilate bulk vacancies, a loading‑unloading effect. This recombination pathway has a lower energy barrier than conventional vacancy diffusion, efficiently eliminating immobile vacancies and enabling self‑healing of radiation damage.

Abstract

Although grain boundaries can serve as effective sinks for radiation-induced defects such as interstitials and vacancies, the atomistic mechanisms leading to this enhanced tolerance are still not well understood. With the use of three atomistic simulation methods, we investigated defect-grain boundary interaction mechanisms in copper from picosecond to microsecond time scales. We found that grain boundaries have a surprising "loading-unloading" effect. Upon irradiation, interstitials are loaded into the boundary, which then acts as a source, emitting interstitials to annihilate vacancies in the bulk. This unexpected recombination mechanism has a much lower energy barrier than conventional vacancy diffusion and is efficient for annihilating immobile vacancies in the nearby bulk, resulting in self-healing of the radiation-induced damage.