Molecular dynamics simulation studies on the plastic behaviors of an iron nanowire under torsion

Abstract

The plastic deformation mechanism of iron (Fe) nanowires under torsion is studied using the molecular dynamics (MD) method by applying an external driving force at a constant torsion speed. We find that the deformation behavior depends on the orientation of the wire. The dislocations in 〈100〉 and 〈111〉 oriented nanowires propagate through the nanowires under torsion, whereas those in 〈110〉 oriented nanowires divide the wire into two parts. The situation that there is a low angle twist grain boundary (GB) in the nanowires is also under consideration. The results reveal that the dislocations are concentrated on the GB in the initial state, presenting different patterns of dislocation network. The networks change depending on the twist direction. They shrink with increase in twist angle but expand with the decreasing twist angle, presenting an asymmetric phenomenon. Our findings can help us more thoroughly understand the plastic deformation mechanism of Fe nanowires under torsion.