First-principles investigation of the energetics of point defects at a grain boundary in tungsten
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- 作者：Jun Chai ; Yu-Hao Li ; Liang-Liang Niu ; Shi-Yao Qin ; Hong-Bo Zhou ; hbzhou@buaa.edu.cn ; Shuo Jin ; Ying Zhang ; Guang-Hong Lu
- 关键词：Tungsten ; Grain boundary ; Point defects ; First-principles
- 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：144-149
- 全文大小：1134 K
- 卷排序：393
文摘
Tungsten (W) and W alloys are considered as the most promising candidates for plasma facing materials in future fusion reactor. Grain boundaries (GBs) play an important role in the self-healing of irradiation defects in W. Here, we investigate the stability of point defects [vacancy and self-interstitial atoms (SIA’s)] in a Σ5(3 1 0) [0 0 1] tilt W GB by calculating the energetics using a first-principles method. It is found that both the vacancy and SIA are energetically favorable to locate at neighboring sites of the GB, suggesting the vacancy and SIA can easily segregate to the GB region with the segregation energy of 1.53 eV and 7.5 eV, respectively. This can be attributed to the special atomic configuration and large available space of the GB. The effective interaction distance between the GB and the SIA is ∼6.19 Å, which is ∼2 Å larger than that of the vacancy-GB, indicating the SIA are more preferable to locate at the GB in comparison with the vacancy. Further, the binding energy of di-vacancies in the W GB are much larger than that in bulk W, suggesting that the vacancy energetically prefers to congregate in the GB.