Molecular Dynamics Studies of Cold Welding of FCC Metallic Nanowires

Abstract

The atomistic-scale cold welding processes for metallic nanowires (NWs) are studied using embedded-atom molecular dynamics (MD) simulations. The mechanical behavior and structural evolution of the FCC metallic nanowires, including Au, Ag, and Cu materials, that experienced a mechanical stretching break and solid-phase pressure welding process, were investigated. The welding temperatures (Tw) ranging from 100 to 900 K were systemically investigated on the effects of welding strength. The ratio of welding strength, Rws, defined as the ratio between the welding strength and the original yield strength of NWs, was employed to identify the welding quality. Simulation results show that the Rws of Au NWs is better than those of Ag and Cu welded at room temperature; however, for welding at high temperatures (600~900 K) the Rws value of Ag NWs is the best. The Rws values of Au NWs using cold welding show less variance than with high temperature welding, reflecting that the application of cold-welding on the Au NWs is highly feasible. The Rws values for NWs with small diameters are generally higher than those with large diameters. The breaking places of the tensile test for the post-welded NWs didnt occur at the welding region, indicating that the broken wires can be robustly reconnected through solid-phase mechanically-assisted welding methods.