Topologically close-packed structure characteristics of the plastic deformation regions of amorphous Cu64.5Zr35.5

Abstract

Understanding the structure of the plastic deformation region is important for improving the mechanical property of amorphous alloys. What kind of structure is conducive to the formation of deformation zone is however still unclear yet. The uniaxial compression of amorphous Cu64.5Zr35.5 has been conducted by a large-scale molecular dynamics simulation. The structure characteristics of the system, especially the deformation regions are systematically investigated based on the newly developed topologically close-packed cluster (TCP) method and the shear transformation zone theory. Results indicate that the deformation process is divided into three stages that can be reasonably explicated by the population and heredity of the 30 top largest standard clusters (LaSCs). It is also found that the response of topologically close-packed (TCP) atoms to strain is closely related with the bond number connected to icosahedra atoms, and the densely packed TCP atoms are more prone to non-affine displacement than the loosely packed ones, which act as the carrier of accommodating plastic deformation. In addition, the plastic deformation units are composed of various types of LaSCs, and the region with local translational symmetry is observed. These findings greatly improve the understanding of the relationship of microstructure and deformation of metallic glasses.