Capture efficiency and bias from the defect dynamics near grain boundaries in BCC Fe using mesoscale simulations

J Chai and S Jin and Z Yu and HX Xu and GH Lu, JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY, 93, 169-177 (2021).

DOI: 10.1016/j.jmst.2021.02.046

The capture efficiency describes the capability of a sink, such as a grain boundary (GB), dislocation, and void, to absorb point defects (PDs). The bias defines the difference in capture efficiency between the absorption of a vacancy and dumbbell at a sink. Complete kinetic information on PDs, including diffusion barriers and diffusion orientations, as well as accurate saddle points, are needed to determine the capture efficiency and bias at a sink accurately, which is computationally demanding. In the present study, the Self-Evolving Atomistic Kinetic Monte Carlo (SEAKMC) method was used to investigate the defect dynamics of PDs near different types of grain boundaries (GBs) (with both < 100 > and < 110 > families) accurately in body- centered cubic (BCC) iron (Fe). The capture efficiency, sink strength, and bias factor of different types of GBs were determined in Fe, which, different from traditional rate theory estimation, showed a distinct capture efficiency, sink strength, and bias in different GBs. The results demonstrate a strong positive correlation between the capture efficiency and the GB strain width, instead of the GB misorientation, GB energy, or GB-PD binding energy, which have been investigated previously. This work provides valuable insight into the radiation- induced microstructural evolution of GBs. (C) 2021 Published by Elsevier Ltd on behalf of Chinese Society for Metals.

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