Structural evolution and mechanical stabilities of head-to-side nanowelding of Cu-Ag bimetallic nanowires via atomistic simulations.

Nanowelding, self-healing and mechanical stabilities of conductive networks of Cu-Ag core-shell nanowires are of vital importance for their extensive applications. In this study, atomistic simulations are used to reveal the head-to-side cold welding behavior, ranging from the welding mechanism, mechanical stabilities of the obtained junction and effects of various conditions. The results show that head-to-side cold welding of Cu-Ag bimetallic nanowires can be excellently completed via atomic interaction and diffusion of atoms. Initial deformation in the junction induced in the welding process and welding temperature are proven to exert a significant influence on the mechanical stabilities of the obtained junction. Three different deformation mechanisms are proposed due to various motivations of dislocations. During the uniaxial tensile test of the junction, the plastic deformation map of initial deformation and welding temperature are expounded in detail. It is revealed that for all the involved welding temperatures explored in our study, the highest tensile strength always belongs to the T-junction with no initial deformation. Otherwise, the intersection will become a serious obstacle to a further process of plastic deformation and lead to abnormally larger elongation and lower strength. These findings are expected to provide an in-depth understanding of the deformation mechanism of bimetallic nanowires and provide valuable theoretical guidance for engineering applications.