The influence of the initial structure in the silver nanowire on the deformation mechanism and the distribution of the breaking positions

Abstract

The tensile behaviors of the silver nanowires with four typical initial structures along with the [111] direction have been investigated by using molecular dynamics simulation. The effects of the initial structures on the generation and propagation of the dislocations have been analyzed systematically, and the relationship between the initial structures and the distribution of the final breaking positions has been discussed. The simulation results revealed that the initial dislocations are generated at the surface and propagate toward the two ends in the single silver nanowire. The reflection from the fixed layers stimulates the stress concentration at the two ends, leading to the necking and the nearly symmetric distribution of the final breaking positions as summarized from 300 samples. However, the existence of the twin boundary impedes the evolution of the dislocations, shortens the process of the plastic deformation. The dislocations are, therefore, accumulated in the region of the twin boundary, generating locally melted clusters and necking. The statistic analysis of the final breaking positions shows a good Gaussian distribution close to the twin boundary. The vacancy with a small size does not exert obvious effect on the formation of the dislocations, although some minor effects can be found during the deformation process. The small vacancy in the single crystal nanowire does not change the stress distribution along the nanowire long axis, and only slightly modifies the final breaking distribution. In the twin nanowire with a small vacancy, both specific structures contribute to the stress concentration at the twin boundary, narrowing the wave length of the breaking position distribution. It is also concluded that the effects of the initial structures present diversity, and the initial structures are also correlated to the effect strength.