Orientation-dependent mechanical properties of Au nanowires under uniaxial loading

Using molecular dynamics simulations with the quantum corrected Sutton–Chen type many-body potential, we have investigated the mechanical responses of Au nanowires along the [1 0 0], [1 1 0], and [1 1 1] crystallographic orientations under compression and tension. The main focus of this work is the orientation-dependent effects on the mechanical properties. The common neighbor analysis method is used to investigate the structural evolution and deformation mechanism of Au nanowires. The simulation results show that the Young’s modulus is strongly dependent on nanowire’s orientation. Under tension, all the oriented nanowires yield via the activities of Shockley partial dislocations, and their plastic deformation is accommodated by partial dislocation activities without twining. Under compression, the [1 0 0] nanowire presents the same yield mechanism together with the deformation twins occurring in its plastic deformation, however, for the [1 1 0] and [1 1 1] nanowires, the buckling instability preferentially occurs, followed by full dislocation activities to carry the plastic deformation without partial dislocations involved. The deformation behaviors indicate that the predication of the Schmidt factor based on bulk single crystal is valid for Au nanowires under compression but not under tension. Our study also shows that the [1 1 0] Au nanowire exhibits a better ductibility, while the [1 1 1] Au nanowire possesses excellent overall mechanical properties.