[SY-B3] Symposium B-3

[SY-B3] Molecular dynamics simulation study of the interaction of Re with interstitial defects in tungsten bulk

Yangchun Chen¹, Jingzhong Fang¹, Ning Gao², Hong-Bo Zhou³, Wangyu Hu⁴, Fei Gao^4,5, ^○Huiqiu Deng^1,4 (1.School of Physics and Electronics, Hunan University, China, 2.Institute of Modern Physics, Chinese Academy of Sciences, China, 3.Department of Physics, Beihang University, China, 4.College of Materials Science and Engineering, Hunan University, China, 5.Department of Nuclear Engineering and Radiological Science, University of Michigan, United States of America)

Tungsten (W) and W-based alloys have been considered as promising candidates for plasma-facing materials (PFMs) in future fusion reactors. However, the neutrons generated in fusion reactions result in not only the cascade damage but also the transmutation products (mainly Re and Os) in W bulk. The irradiation defects and transmutation products will have a serious effect on the service behaviors of W PFMs under the condition of fusion irradiation. With molecular dynamics simulations and W-Re potentials developed recently in our group, we have systematically investigated the interaction between Re atom/cluster and interstitial defects in W bulk. It is found that: (1) the self-interstitial atoms (SIAs) and interstitial Re atoms are energetically favorable to align along <111> direction in the form of W-W and Re-W dumbbell/crowdion, respectively; (2) the SIA clusters and 1/2<111> interstitial dislocation loops can undergo fast migration along <111> direction and their migration barriers (< 0.1 eV) are nearly independent of defect size; (3) Re atoms inhibit the migration and growth of SIA clusters, due to their strong attractions; (4) newly formed Re-Re dumbbells and Re-W mixed dumbbell clusters are thermally stable and immobile, which can serve as the trapping center for subsequent Re-W mixed dumbbell, leading to the growth of Re clusters in W. The present work is helpful for understanding the interaction of Re with interstitial defects and dislocation loops and the initial nucleation mechanism of Re atoms in bulk W, and the results can also be used to supply more accurate inputs for larger-scale simulations such as object kinetic Monte Carlo simulations.