Superplastic dual-phase nanostructure Mg alloy: A molecular dynamics study

Abstract

The introduction of amorphous phase and amorphous-crystalline interfaces is a new approach for enhancing mechanical performance of the Mg-based composite materials. In this work, we use molecular dynamics simulation method to explore the effect of amorphous phase size on the mechanical behavior of dual-phase nanostructure Mg alloy under tensile loading. The results show that two different deformation mechanisms of the dual-phase nanostructure Mg alloy occur depending on crystalline phase size (d) and amorphous thickness (t). There is a critical amorphous thickness (tc) for each sample to achieve nearly perfect plasticity, regardless of d. When t < tc, the plasticity of dual-phase nanostructure Mg alloy is provided by amorphous and crystalline phase. However, the plasticity is provided only by amorphous phase, the crystalline phase hardly participates in plastic deformation when t > tc. The results also indicate that reducing d and increasing t is consistent for improving the plastic effect of the dual-phase nanostructure Mg alloy. The optimal matching relationship between d and t is given. Moreover, some qualitative and quantitative analysis about the plastic deformation behavior of dual-phase nanostructure Mg alloy are also presented.