Determining the capture efficiency of grain boundaries in bcc tungsten: the critical role of grain boundary characteristics

Capture efficiency is a key metric for evaluating the ability of grain boundaries (GBs) to absorb irradiation defects. However, the accurate description of capture efficiency and clarifying the influence of GB characteristics remains a formidable challenge. In this study, we systematically investigate the interaction of point defects (PDs) with different GBs in tungsten using molecular statistic/dynamic, elastic dipole tensor, and kinetic Monte Carlo methods. It is found that the formation energy and absorption range of PDs in high-angle GBs (HAGBs) is much higher than that in other GBs, implying the strong interaction strength of PDs with HAGBs. More importantly, we emphasize the significance of net strain field (total strain field minus absorption range), which shows a strong positive correlation with capture efficiency of GBs. Therefore, different from the interaction strength, the capture efficiency and sink strength of low-angle GBs (LAGBs) are much higher than that of HAGBs, which is in good agreement with the experiments. Besides, temperature and grain size show significant sensitivity in the capture efficiency for different GBs. The capture efficiency and sink strength of LAGBs are 3–4 times higher than that of HAGBs at 600 K, while this difference decreases to below 50 % at 1200 K. Additionally, the capture efficiency for a 10 nm grain size increases by approximately 0.3–1.2 times compared to 40 nm. These results not only explicitly clarify the influence of GB characteristics on the capture efficiency of GBs for PDs, and provide an important reference to the development of radiation-resistant materials.