Enhancing the plasticity of noncrystalline Cu-Zr multilayer: Insights from molecular dynamics simulations

Amorphous alloys with pre-fabricated defective structure have been proved to have splendid ductility, making it a prospective second phase for metallic glass (MG) matrix composites. Here, the plastic deformation behavior of amorphous-amorphous (A/A) dual-phase nano-multilayers is successfully simulated by performing molecular dynamics method. The results reveal that the soft phase with structural defects in A/A nano-multilayers plays a key role in improving plasticity of MG. Specifically, when the density of structural defects is small, most of plastic deformation dominated by a single shear band is mainly confined to the flabby soft phase. A suitable density makes the clusters with large atomic shear strain more likely to be activated at the A/A interfaces, thereby linking the shear deformation between the two amorphous phases and promoting a relatively uniform global plasticity. Nevertheless, the free volume gradient caused by excessive density difference between two amorphous phases will create the rapid release of large stress at the A/A interfaces. The results indicate that the introduction of A/A interfaces and soft MG phase is an effective approach for significantly improving the plasticity without damage and expense the strength of MG.