The Role of Grain Boundaries under Long-Time Radiation

TL;DR

This paper develops a coarse-grained model to understand how grain boundaries influence long-term radiation effects in materials, linking microstructure to microstructural evolution and validating with experiments.

Contribution

It introduces a new formula for sink strength based on grain size and incorporates coupled evolution of grain boundaries and point defects in a coarse-grained framework.

Findings

Point defect sources accelerate grain shrinking.

Radiation induces extension of twin boundary sections.

Model aligns well with experimental observations.

Abstract

Materials containing a high proportion of grain boundaries offer significant potential for the development of radiation-resistent structural materials. However, a proper understanding of the connection between the radiation-induced microstructural behaviour of grain boundary and its impact at long natural time scales is still missing. In this letter, point defect absorption at interfaces is summarised by a jump Robin-type condition at a coarse-grained level, wherein the role of interface microstructure is effectively taken into account. Then a concise formula linking the sink strength of a polycrystalline aggregate with its grain size is introduced, and is well compared with experimental observation. Based on the derived model, a coarse-grained formulation incorporating the coupled evolution of grain boundaries and point defects is proposed, so as to underpin the study of long-time morphological evolution of grains induced by irradiation. Our simulation results suggest that the presence of point defect sources within a grain further accelerates its shrinking process, and radiation tends to trigger the extension of twin boundary sections.