Molecular Dynamics Simulation of Dynamic Migration of ≪inline-Formula><tex-math Id="m3">\begin{document}$\boldsymbol {\langle 100\rangle} $\End{document}</tex-Math><alternatives><graphic Xmlns:Xlink="http://www.w3.org/1999/xlink" Xlink:Href="24-20230651_M3.jpg"/><graphic Xmlns:Xlink="http://www.w3.org/1999/xlink" Xlink:Href="24-20230651_M3.png"/></alternatives></inline-formula> Interstitial Dislocation Loops under (010) Surfaces of Pure W and W …

In the fusion irradiation environment, dislocation loop defects occurring under plasma-facing tungsten surface affect its mechanical properties and hydrogen/helium retention. This paper studies the dynamic behaviors of a \begin{document}$\langle 100\rangle $\end{document} loop with a radius of 1 nm under the W \begin{document}$(010)$\end{document} surface by using molecular dynamics simulation at the atomic level. It is found that the dislocation loop direction, bulk temperature, depth, and helium atoms can greatly affect the motion of dislocation loops, showing that the \begin{document}$ {\boldsymbol{b}}/ / {\boldsymbol{n}} $\end{document} dislocation loop, where \begin{document}$ {\boldsymbol{b}} $\end{document} is the Burgers vector and \begin{document}$ {\boldsymbol{n}} $\end{document} denotes the surface normal direction, tends to move towards the surface and the \begin{document}$ {\boldsymbol{b}} \bot {\boldsymbol{n}} $\end{document} dislocation loop tends to stay in the material. In the course of its migration, the habit plane of dislocation loop may change and the internal stress decreases gradually. The probability of a \begin{document}$ {\boldsymbol{b}}/ / {\boldsymbol{n}} $\end{document} dislocation loops escaping from the surface is over 90% when the temperature is higher than 800 K and their initial depth is less than 5 nm. The \begin{document}$ {\boldsymbol{b}} \bot {\boldsymbol{n}} $\end{document} dislocation loop can escape from the surface when the temperature is 800 K and the initial depth is less than 2 nm. It is found that \begin{document}$\langle 100\rangle $\end{document} dislocation loops decompose into \begin{document}${1 \mathord{\left/ {\vphantom {1 2}} \right. } 2}\langle 111\rangle $\end{document} dislocations at elevated temperatures. Helium atoms impede the migration of dislocation loops and increase their retention time. The existence of dislocation loops results in the uneven distribution of helium atoms under the W surface, and will potentially affect the surface morphology of tungsten.