Dynamic Void Growth and Shrinkage in Mg under Electron Irradiation

We report <i>in situ</i> atomic-scale investigation of late-stage void evolution, including growth, coalescence and shrinkage, under electron irradiation. With increasing irradiation dose, the total volume of voids increased linearly, while the nucleation rate of new voids decreased slightly and the total number of voids decreased. Some voids continued to grow while others shrank to disappear, depending on the nature of their interactions with nearby self-interstitial loops. For the first time, surface diffusion of adatoms was observed to be largely responsible for the void coalescence and thickening. These findings provide fundamental understanding to help with the design and modeling of irradiation-resistant materials.

本研究报道了电子辐照环境下后期空洞演化（包括生长、合并与收缩）的原位（in situ）原子尺度观测结果。随着辐照剂量的提升，空洞总体积呈线性增长，而新空洞的形核速率略有下降，空洞总数量亦随之减少。部分空洞持续生长，其余则收缩直至消失，这取决于其与附近自间隙环（self-interstitial loops）的相互作用特性。本研究首次观测到，吸附原子（adatoms）的表面扩散行为是空洞合并与增厚的主要成因。上述研究结果为抗辐照材料的设计与建模提供了基础理论依据。