Atomic study of the trapped and migration patterns of point defects around screw dislocation in tungsten

Abstract

The interaction of 1/2 〈111〉 screw dislocation and point defects, including vacancy and self-interstitial atom (SIA), was investigated by molecular dynamics (MD) simulations. Molecular statics (MS) are used to analyze the factors affecting the binding energy of point defects around the dislocation. The results show that the point defects around the dislocation core have the highest binding energy. In addition, we use elasticity theory to find that the point defects binding is interrelated to strain distribution of dislocation and the residual stress of point defects. Furthermore, nudged elastic band (NEB) calculations have been applied to find that vacancy and SIA tend to migrate along the dislocation line around the core region. The results can clearly show the interaction behavior of point defects and screw dislocation, and provide a reasonable explanation for the diffusion mechanism of mono-vacancy and a single SIA around the dislocation line.

Keywords

• Screw dislocation
• Vacancy
• Self-interstitial atom
• Binding energy
• Diffusion mechanism