Atomic-scale insights into dislocation-induced vibrational softening mechanisms: molecular dynamics simulations and modeling

Dislocation dynamics during vibration-assisted deformation is difficult to trace by traditional experimental methods. In this paper, the molecular dynamics simulations were designed to describe the transient responses of substructures during vibration-assisted tensile deformation. The propagation of vibrational energy and its effect on atomic arrangement inside models were revealed. The annihilation characteristics of dislocations to overcome short-range and long-range obstacles were distinguished. The results show that the proportion of Shockley partial dislocation transformed into stair-rod dislocation is reduced by 14% with superimposed vibration. The vibrational energy activates the atomic rotation near grain boundaries, reduces the order of atoms by 47%, and improves the coordination deformation ability of the grain boundaries. Furthermore, the influence of vibration field on the dislocation annihilation was quantified, and a vibration softening stress prediction model was established.