Grain boundary metastability controls irradiation resistance in nanocrystalline metals

TL;DR

This paper demonstrates that the irradiation resistance of nanocrystalline metals is governed by the metastability of grain boundaries, which dynamically changes under irradiation, affecting defect absorption and material stability.

Contribution

It introduces a radiation damage evolution model that accounts for metastable grain boundary microstates and their impact on defect absorption during irradiation.

Findings

Denuded zones can collapse with accumulated damage.

Microstate changes influence defect absorption capacity.

Defect networks produce detectable Nye-tensor signals.

Abstract

Grain boundaries (GBs) in polycrystalline materials are powerful sinks for irradiation defects. While standard theories assume that the sink efficiency of a grain boundary is defined solely by its character before irradiation, recent evidence conclusively shows that the irradiation sink efficiency is a highly dynamic property controlled by the intrinsic metastability of GBs under far-from-equilibrium irradiation conditions. In this paper, we reveal that the denuded (i.e., defect-free) zone, typically the signature of a strong sink, can collapse as irradiation damage accumulates. We propose a radiation damage evolution model that captures this behavior based on the emergence of a series of irradiation defect-enabled metastable GB microstate changes that dynamically alter the ability of the GB to absorb further damage. We show that these microstate changes control further defect absorption and give rise to the formation of a defect network that manifests itself as a net Nye-tensor signal detectable via lattice curvature experiments.