Effect of rare earth element on amorphization and deformation behavior of crystalline/amorphous dual-phase Mg alloys

The crystalline/amorphous (C/A) dual-phase structure is a new design strategy to improve the mechanical properties of Mg alloys. Here, the effect of the content of rare-earth element Y on the deformation mechanism and mechanical behavior of the C/A Mg/(MgCu)100-xYx dual-phase Mg alloys under tensile loading is investigated by molecular dynamics simulation. The results show for the first time that the amorphous phase thickness of the alloys increases obviously after relaxation, which is mainly due to the existence of element Y in amorphous phase. And with the increase of the content of element Y, the thickness of amorphous phase increases. The results indicate that the diffusion of element Y from amorphous phase to amorphous-crystalline interface (ACI) promotes the migration of ACI towards crystalline phase (i.e., the amorphization of crystalline phase). The results further pointed out that the amorphization of Mg alloys depends on two factors: one is that the amorphous phase contains a certain concentration of element Y, and the other is the existence of ACI. The results show that there is a critical amorphous phase thickness of the dual-phase Mg alloys, that is, the critical content of Y element, which can make it achieve nearly perfect plasticity.