title: Dislocation-enhanced experimental-scale vacancy loop formation in hcp Zirconium in one single collision cascade.
abstract: Large defects are the main factor leading to the degradation of material properties under irradiation environments. It is commonly assumed that the large defects are mainly formed through cluster growth under continuous irradiations. Besides this mechanism, recent experiments and simulations show that sometimes an individual ion can also directly create a large defect. Here we report a novel mechanism for the formation of the large defects, as discovered by our Molecular Dynamics (MD) simulations of the collision cascades in hcp Zirconium (Zr): a pre-existing edge dislocation (ED) can significantly promote the nucleation of the vacancy clusters, and even facilitate the direct formation of an experimental-scale large vacancy loop (about 3 nm) in only one single displacement cascade. This dislocation-related mechanism may be the key for understanding the experimental results in the low-dose irradiated Zr where the high-density large dislocation loops are observed but difficult to be explained by the two mechanisms mentioned above. Considering that intrinsic dislocations exist in nearly all crystalline materials, our results provide a significant concept: pre-existing dislocations have a strong influence on the primary damage production, and taking them into account is indispensable for assessing and improving the material's irradiation-resistance.
authors: Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, People's Republic of China, 621999.
authors: Wei
authors: W
authors: Zhou
authors: State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing, People's Republic of China, 100871.
authors: Jiting
authors: J
authors: Tian
authors: Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, People's Republic of China, 621999.
authors: Jian
authors: J
authors: Zheng
authors: State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing, People's Republic of China, 100871.|Center for Applied Physics and Technology, Peking University, Beijing, People's Republic of China, 100871.
authors: Jianming
authors: J
authors: Xue
authors: Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang, People's Republic of China, 621999.
authors: Shuming
authors: S
authors: Peng