科研之友
微信
新浪微博
Facebook
分享链接
摘要
Increasing the density of sinks such as grain boundaries and interfaces for irradiation-induced defects and implanted ions has been demonstrated to be an effective way to improve the irradiation resistance of materials. To understand the effects of grain boundaries on the degradation mechanism of nano structured materials, nanocrystalline tungsten was fabricated by high pressure torsion (HPT-W). Morphological changes of HPT-W and coarse grain tungsten (CG-W) during helium ion irradiation were evaluated in situ in a helium ion microscopy. It has been shown that the degradation mechanisms of CG-W and HPT-W are remarkably different. Blister occurs on the surface of CG-W when the irradiation dose increases up to 5.0 x 10(21) m(-2), and orientation dependence of blistering has been observed. However, no blister is formed on the surface of HPT-W even when the irradiation dose increases up to 1.0 x 10(23) m(-2). Instead, crack formation along grain boundaries is the major degradation mechanism during helium irradiation of HPT-W, supporting a different irradiation degradation mechanism. This explains the unprecedented irradiation tolerance of HPT-W in terms of blistering. Molecular dynamics results also show that grain boundaries and helium clusters play an important role during the propagation of a crack. The zigzag crack planes are attributed to the coalescence and growth of helium blister/bubble-induced crack. The results document that grain boundaries play decisive roles in the irradiation resistance of nano structured materials, and provide a new perspective to the design of plasma facing materials with excellent irradiation resistance. It is thus suggested that excellent irradiation resistance can be achieved by a meticulous design of grain boundaries based on "interface engineering".
- 出版日期2018-4-1
- 单位核工业西南物理研究院; 中国工程物理研究院; 中国科学院理化技术研究所; 北京航空航天大学
