[SY-I9] Symposium I-9

[SY-I9] The Role of Grain Boundaries under Long-Time Radiation

^○Jing Luo¹, Yichao Zhu¹, Xu Guo¹, Yang Xiang³, Stephen Jonathan Chapman² (1.Dalian University of Technology, China, 2.Mathematical Institute, University of Oxford, UK, 3.Department of Mathematics, The Hong Kong University of Science and Technology, Hong Kong)

Materials containing a high proportion of grain boundaries offer significant potential for the development of radiation-resistent structural materials. However, a proper understanding of the connection between the radiation-induced microstructural grain boundary behaviour and its impact at long natural time scales is still missing. To bridge this gap in time scales, a rigorously coarse-grained formulation describing the coupled evolution of point defects and low-angle tilt grain boundaries is proposed. The derived formulation captures well the radiation-induced climb behaviour of grain boundary dislocations, which leads to asymmetry in grain shape evolution. It also reveals that the presence of point defect sources within a grain further accelerates its shrinking process, and radiation tends to elongate the twin boundary sections. Based on the proposed formulation, it is predicted for the first time that the minimum dimension of a polycrystalline aggregate needed for shielding the point defect concentration to a prescribed level scales with its grain boundary fraction at a sublinear rate.