Inferring radiation-induced microstructural evolution in single-crystal niobium through changes in thermal transport

Ion beams enable accelerated radiation exposure experiments, but traditional destructive post-irradiation examination techniques remain time-consuming. Here, measurements of thermal diffusivity are used to monitor microstructural changes in single crystal niobium irradiated with Si³⁺ ions up to 1.9 dpa (5.1 × 10¹⁵ ions/cm²). Changes in thermal transport are correlated to defect generation and clustering through dose-microstructure relationships. These measurements are made using transient grating spectroscopy (TGS), a multi-modal, non-destructive, rapid characterization technique. This work demonstrates that in this low-dose point defect clustering regime, direct measurements of thermal properties are a powerful tool for understanding irradiation-induced microstructure evolution.