The effects of stacking fault (SF) and temperature on the mechanical properties of nano-polycrystal Mg under tension loading are investigated by molecular dynamics simulations. The interatomic potential of embedded atom method (EAM) is used as the Mg-Mg interaction. The computational results show that the yield strength of nano-polycrystal Mg can be obviously enhanced when stacking fault is introduced into grains, and the effect of SF on the Young's modulus of nano-polycrystal Mg is very small. The results also show that tensile twins and new grain at 300.0 K are nucleated and initiated at grain boundaries, growing continuously with the increase of strain. The dihedral angel between the (1000) plane of new grain and the X-Y plane is about 35°. In other words, the nucleation and the growth of twins and new grains are the predominant deformation mechanism for nano-polycrystal Mg at 300.0K. We also find that at 10.0K the dislocation nucleation and slip are the predominant modes of the plastic deformation for nano-polycrystal Mg.

Project supported by the Key Program of the National Natural Science Foundation of China (Grant No. 10932008), the National Natural Science Foundation of China (Grant No. 10902083), and the Program for New Scientific and Technological Star of Shaanxi Province (Grant No.2012KJXX-39).