Mechanical properties of Au nanowires under uniaxial tension with high strain-rate by molecular dynamics

The deformation behaviour of Au nanowires subjected to uniaxial tension at high strain-rate under different temperatures is studied by molecular dynamics simulation along [001], [011], and [111] elongation directions, respectively. The stress distributions and the radial distribution functions of the structure of the nanowires are evaluated and discussed. It is seen that the stress-strain curves are quite different from those of the bulk material. Moreover, the microstructures of nanowires are transformed first from FCC to face-centred-orthorhombic-like crystalline, and then changed to the amorphous state. The first neighbouring distance in the radial distribution functions along the [001] direction is clearly split into two peaks. It appears that the ductility of the nanowires at high strain-rate is higher than the corresponding macroscopic cases. The magnitudes of Young's modulus and the maximum strength along different crystalline directions are evaluated and compared with each other. They tend to decrease as the temperature increases. It may be predicted from our simulations that the conductance at high strain-rate deformation may be a continuous function of elongation due to the smooth reduction of area.