Cold Welding of Gold and Silver Nanowires: A Molecular Dynamics Study

Recently a new possibility of welding was experimentally shown in the case of gold nanowires (NWs) at ambient temperatures, without need of additional heat and with low pressures, called cold welding (Nat, Nanotechnol. 2010, 5, 218). Using molecular dynamics with effective potentials, we present the simulated cold welding of gold, silver, and silver-gold NWs with diameters of 4.3 nm at 300 K. We show the cold welding is a possible process in metal NWs and that these welded NWs, even after losing their crystalline structure after breaking, can reconstruct their face-centered cubic structure during the welding process with the result of very few defects for the final cold welded NWs. The stress tensor shows a low average value during welding with oscillations indicating tension and relaxation stages. Small pressures are required for the process to occur, resulting in a fairly perfect crystal structure for the final NW after being broken and welded. Cold welding is the result of nanoscale sample dimensions and mechanically assisted fast surface-atom diffusion. We also showed that the process occurs using different metals welded together and that the quality of the welding (resistance to rupture) of Ag-Au NW is good. Our results are in good agreement with the experiments.