Molecular dynamics of grain boundaries on the evolution behavior of irradiation defects in austenitic steels

MJ Li and SY Jiang and YX Yang and ZF Tong, COMPUTATIONAL MATERIALS SCIENCE, 259, 114133 (2025).

DOI: 10.1016/j.commatsci.2025.114133

This study simulated cascade collision process of primary knock-on atoms with an energy of 10 keV in austenitic stainless steel alloy system (Fe-18at.%Cr-10at.%Ni) and grain boundary systems (Sigma 3(111), Sigma 3(112), Sigma 27(115)) at different temperatures using molecular dynamics. The extent of material damage after the cascade process in alloy systems-both with and without grain boundaries-was analyzed, along with the associated defect types. The stability of point defects at grain boundaries was first evaluated through molecular statics simulations, followed by molecular dynamics simulations to further investigate underlying mechanisms of grain boundary effects. The strength of the grain boundary effect could be evaluated by calculating the absorption efficiency. Computational results demonstrate that the formation energy of point defects near absorption-sink grain boundaries decreases significantly. A positive correlation exists between grain boundary energy and defect absorption capacity, where grain boundaries with strong absorption sinks can effectively capture and stabilize defects at their interfaces. Therefore, from a microscopic perspective, it is revealed that grain boundaries can play a role in strong absorption traps, which provides theoretical guidance for the subsequent study of grain boundary effects.

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