Effect of stacking fault and amorphous boundary on plastic deformation mechanism of dual-phase nanostructure Mg alloys

Abstract

Dual-phase nanostructure model is an effective method to improve the plasticity of Mg alloys. Here, molecular dynamics simulation is performed to investigate the influence of stacking fault (SF) and amorphous boundary (AB) on the deformation mechanism of dual-phase crystal/amorphous nanostructure Mg alloys under tensile loading. The results show that with the increase of AB spacing, the plastic deformation mode of dual-phase nanostructure Mg alloys containing SFs with large SF spacing converts from the generation and growth of new grains in crystalline phase to the plastic deformation dominated by amorphous phase. When the AB spacing reaches a critical value, the plastic deformation of dual-phase nanostructure Mg alloys is completely provided by amorphous phase, and the crystalline phase hardly participates in plastic deformation. However, the results also indicate that when the SF spacing in the crystalline phase is relatively small, the crystalline phase still contributes to the plastic deformation of Mg alloys to a certain extent, even if the AB spacing is large. These analysis shed light on that the introduction of SFs may promote the formation of new grains, and the deformation mechanism of dual-phase nanostructured Mg alloys is not only related to the AB spacing of amorphous phase, but also to the SF spacing of crystalline phase.