[SY-B10] Symposium B-10

[SY-B10] Sink strengths of point defects near tilt grain boundaries: A phase field model

^○Pengchuang Liu¹, Songlin Zheng², Pengcheng Zhang¹, Sanqiang Shi³, Kaiguo Chen² (1.Institute of Materials, China academy of engineering physics, China, 2.Institute of Fluid Physics, China academy of engineering physics, China, 3.Department of Mechanical Engineering, The Hong Kong Polytechnic University, Hong Kong)

Dislocations and grain boundaries are perfect sinks for point defects (PDs), the ability of sinks to absorb point defects is a critical factor for the irradiation damage behaviors of materials. Phase field (PF) method was used to describe low angle tilt grain boundaries which composed of edge dislocations. Evolution processes of tilt grain boundaries and PDs were coupled in a same PF model. We considered the climbing mechanism rather than fixed dislocations. Sink strengths of grain boundaries were computed based on the obtained steady-state average PDs concentrations. We studied the saturation properties of tilt grain boundaries and obtained the relations between sink strengths and dislocation densities. PDs generation rate represents the irradiation intensity, it is also undemanding to take into account in this PF model. Elastic interactions of point defects and dislocations have great impacts on the sink properties of tilt grain boundaries. We compared the effects of different eigenstrains and applied stresses and got the connections between sink strengths and climbing speeds of dislocations. A physical phase-field model was built, which covered material processes to study sink properties of tilt grain boundaries without additional assumptions. We compared the calculated results with the theoretical and existing ones, clarified the inherent differences between them, results are favorable for designing extremely radiation tolerant materials.