An operational window for radiation-resistant materials based on sequentially healing grain interiors and boundaries

TL;DR

This paper introduces an operational window for designing radiation-resistant materials by understanding the distinct healing times of grain interiors and boundaries, emphasizing the importance of boundary recovery for improved radiation tolerance.

Contribution

It reveals the critical role of grain boundary healing times in radiation resistance and proposes a new framework to predict material performance based on temperature, dose-rate, and grain size.

Findings

Healing of grain boundaries takes longer than grain interiors.

A high-energy barrier peak indicates delayed defect recombination at boundaries.

The radiation-endurance window guides the development of more resilient materials.

Abstract

Design of nuclear materials with high radiation-tolerance has great significance1, especially for the next generation of nuclear energy systems2,3. Response of nano- and poly-crystals to irradiation depends on the radiation temperature, dose-rate and grain size4-13. However the dependencies had been studied and interpreted individually, and thus severely lacking is the ability to predict radiation performance of materials in extreme environments. Here we propose an operational window for radiation-resistant materials, which is based on a perspective of interactions among irradiation-induced interstitials, vacancies, and grain boundaries. Using atomic simulations, we find that healing grain boundaries needs much longer time than healing grain interiors. Not been noticed before, this finding suggests priority should be thereafter given to recovery of the grain boundary itself. This large disparity in healing time is reflected in the spectra of defects-recombination energy barriers by the presence of one high-barrier peak in addition to the peak of low barriers. The insight gained from the study instigates new avenues for examining the role of grain boundaries in healing the material. In particular, we sketch out the radiation-endurance window in the parameter space of temperature, dose-rate and grain size. The window helps evaluate material performance and develop resistant materials against radiation damage.