Effects of crystal orientation and temperature on the deformation mechanism and mechanical property of Cu nanowire

Abstract

The effects of crystallographic direction and temperature on the deformation mechanism and properties of Cu nanowire (NW) are studied via systematic simulations and theoretical analysis. It is found that the elastic module, yield stress and yield strain are quite different for five oriented NWs. As the crystallographic orientation of NW varies, both the yield stress and the yield strain firstly reduce to the minimum value, then gradually increase. Furthermore, the evolutions of flow stress after yield point are also obviously different for five oriented NWs, which are associated with the plastic deformation mechanisms. With the crystallographic orientation of NW varying, the simulated atomic snapshots show that the dominant deformation mechanism transforms from the shuffling-assisted single dislocation-nucleation to the collective dislocation-nucleation, then to the twinning migration, and finally to the combination of dislocation glide and microtwinning. According to the normal stress perpendicular to the slip plane and shear stress on the slip plane, the authors theoretically predict the deformation mechanisms for different oriented NWs, which turn to be in good consistent with the authors' observed deformation mechanisms. Besides, they also propose that the temperature effects are different for different oriented NWs.