Atomic simulation of interaction mechanism between dislocation and amorphous phase in dual-phase crystalline/amorphous Mg/MgAl alloys

Abstract

The introduction of the amorphous phase and crystalline–amorphous interface (CAI) is an efficient approach for enhancing the mechanical performance of the Mg-based composites. Here, the interaction behavior between dislocations and amorphous phase in the dual-phase crystalline/amorphous Mg/MgAl alloys is investigated under tensile loading by molecular dynamics simulation. The results indicate that when the amorphous phase orientation (i.e., the angle between the tensile direction and the normal direction of CAI) is 0°, the amorphous phase with a larger thickness (≥ the critical value of 2.0 nm) can effectively prevent dislocation slips, and the plastic deformation of the alloys is dominated by the nucleation and growth of a new grain in the crystalline phase. The research also shows that, with the increase in the amorphous phase orientation from 0° to 90°, the deformation mechanism changes from dislocation activities to CAI slips and then again to the nucleation and movement of dislocations. The change in the deformation mode is attributed to the variation of the quasi-Schmid factor of the amorphous layer in different orientations of the amorphous phase. Moreover, some qualitative and quantitative analyses about the plastic deformation behavior of the dual-phase nanostructure Mg alloy are also presented.