Molecular dynamics understanding on tensile behaviours of cold welding experiments of oriented ultra-thin gold nanowires

Abstract

A molecular dynamic study on cold welding experiments of ultra-thin gold nanowires in <100> orientation was carried out at room temperature to understand their tensile behaviours. In order to investigate the size effects on cold welding, four kinds of ultra-thin gold nanowires with different diameters are simulated and analysed respectively. We studied the principle of cold welding through observing how the nanowire lattices evolve during the processes of cold welding and stretching. The strain–stress curves of single nanowire and welding nanowire are obtained and analysed, and then the young’s modulus and yield strength are compared each other with corresponding diameters. The observation from the simulation results gives that the atoms in the solder joints would regroup into new lattices during cold welding processes. For the nanowires with small diameters, including Φ3 nm and Φ4 nm, the mechanical properties, such as the young’s modulus, yield strength and yield strain, are all different between single nanowire and welding nanowire with the same diameter, and the single nanowire holds greater ones. As the nanowires’ diameters larger than 4 nm, their mechanical properties are almost the same in the elastic period with corresponding diameters.