Atomistic simulations of screw dislocations in bcc tungsten: From core structures and static properties to interaction with vacancies

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• 作者：Ke Xu^a ; ^b ; Liang-Liang Niu^a ; ^b ; ^c ; Shuo Jin^a ; ^b ; ^{jinshuo@buaa.edu.cn} ; Xiaolin Shu^a ; ^b ; Hongxian Xie^d ; Lifang Wang^a ; ^b ; Guang-Hong Lu^a ; ^b
• 关键词：Screw dislocations ; Tungsten ; Vacancies ; Atomistic simulations
• 刊名：Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
• 出版年：2017
• 出版时间：15 February 2017
• 年：2017
• 卷：393
• 期：Complete
• 页码：174-179
• 全文大小：2549 K
• 卷排序：393

文摘

Atomistic simulations have been used to investigate the core structures, static properties of isolated 1/2 <1 1 1> screw dislocations, and their interaction with vacancies in bcc tungsten (W) based on three empirical interatomic potentials. Differential displacement maps show that only one embedded atom method potential is able to reproduce the compact non-degenerate core as evidenced by ab initio calculations. The obtained strain energy and stress distribution from atomistic simulations are, in general, consistent with elasticity theory predictions. In particular, one component of the calculated shear stress, which is not present according to elasticity theory, is non-negligible in the core region of our dislocation model. The differences between the results calculated from three interatomic potentials are in details, such as the specific value and the symmetry, but the trend of spatial distributions of static properties in the long range are close to each other. By calculating the binding energies between the dislocations and vacancies, we demonstrate that the dislocations act as vacancy sinks, which may be important for the nucleation and growth of hydrogen bubbles in W under irradiation.