Atomic simulation of deformation behavior of dual-phase crystalline/amorphous Mg/Mg-Al nanolaminates

Dual-phase crystalline/amorphous nanostructure model is an effective method to improve the mechanical properties of Mg alloys. The effects of amorphous thickness and crystal orientation on the plastic deformation mechanism of dual-phase crystalline/amorphous Mg/Mg-Al nanolaminates under tensile loading are investigated by using molecular dynamics simulation method. The results indicate that for the model in which the crystal phase orientation is [0 0 0 1] along tensile direction, with the increase of amorphous thickness, the deformation mechanism of samples changes from localized deformation dominated by generalized shear band (GSB) to the homogeneous plastic deformation. Here, the uniform plastic deformation is achieved by combining complete basal-prismatic (BP) transformation in crystal phase and uniformly distributed shear transformation zones in amorphous phase. The results also show that for the large amorphous thickness model, there is an obvious secondary hardening stage in the plastic deformation process, and the large amorphous phase is conducive to the formation of BP interface. However, when the crystal orientation is [1- 0 1 0] along tensile direction, all samples undergo local plastic deformation dominated by GSB, which indicates that the plastic deformation mechanisms of dual-phase nanolaminates depend not only on the thickness of amorphous phase, but also on the orientation of crystalline phase.