Cold welding of copper nanowires with single-crystalline and twinned structures: A comparison study

• Cold welding processes of copper nanowires were explored by molecular simulations.
• Twinned nanowires can be successfully welded through small loadings.
• Welding processes were compared between single-crystalline and twinned nanowires.

In this article, molecular simulations were adopted to explore the cold welding processes of copper nanowires with both single-crystalline and fivefold twinned structures. It was verified that the twinned nanowires exhibited enhanced strength but lowered elastic limit and ductility. Both nanowires could be successfully welded through rather small loadings, although their stress–strain responses toward compression were different. Meanwhile, more stress was accumulated in the twinned nanowire due to repulsive force of the twin boundaries against the nucleation and motions of dislocations. Moreover, by characterizing the structure evolutions in the welding process, it can be ascertained that perfect atomic order was finally built at the weld region in both nanowires. This comparison study will be of great importance to future mechanical processing of metallic nanowires.