Computational study of a screw dislocation interacting with a stacking-fault tetrahedron

A numerical simulation study of the intersection process of a moving 1/2[110] screw dislocation with a perfect stacking-fault tetrahedron (SFT) in an fcc nickel crystal is carried out using molecular dynamics for different many-body potentials. When the glide plane of the screw dislocation coincides with one of the planes of the SFT, the interaction involves several dislocation reactions, jog line formation and bending of dislocation segments. The complex atomic processes are illustrated in detail and are shown to depend on the relative orientation of the defect and moving dislocation. In most cases, the jogs disappear quickly, but in special cases the jog lines in the dissociated dislocation remain even after the interaction process with the SFT, dragging some vacancies away. While in this geometrical set-up the main effect of the intersection is the ledge formation on the SFT, when the moving dislocation intersects the SFT in the middle part, it leads to slip and the separation of the SFT into two parts. Finally, if the screw dislocation passes at non-zero distance from the SFT the elastic interaction does not lead to any deformation of the SFT.