Recovery of radiation induced defects via nanovoids in bulk pure Fe

Abstract

Abstract Enhancing radiation tolerance in materials is at the forefront of materials science. Grain and/or phase boundaries in nanocomposite, nanophase, and nanofoam materials have been shown to provide a promising route to enhancing radiation tolerance. Here, through a combination of positron annihilation spectroscopy, transmission electron microscopy, and computer simulation, we show that pre-existing voids in bulk single phase Fe without the incorporation of nanograins or nanotwins provide sinks for interstitials and vacancies and enhance self-healing of radiation induced defects. Atomistic simulations revealed that the interaction of collision cascades with preexisting voids transforms them into vacancy loops. At higher doses as they absorb vacancies, they regain their original size, an interesting mechanism that explains the experimental observations of voids shrinking, disappearing, then reappearing in their original form. This could lead to transient behavior delaying radiation damage to higher doses or cyclic behavior mitigating radiation damage.