Networked interpenetrating connections of icosahedra: Effects on shear transformations in metallic glass

The local structures of metallic glasses have been analyzed previously in term of various types of short-range order (SRO). However, the SRO alone, neglecting the interconnection of neighboring icosahedra to medium range and beyond, is insufficient to account for the structure-property relationship in metallic glasses. In this study, we use molecular dynamics (MD) simulations of Cu-Zr binary metallic glasses to examine the effects of the next level of structural hierarchy: the interpenetrating connection of icosahedra (ICOI) and the linkage of the medium-range ICOI patches to form networks of icosahedra over extended range. The mechanical properties of these metallic glasses, especially the shear transformations that mediate plasticity, are found to be dependent on the degree of ICOI and development of the ICOI network. The evolution of the ICOI network during shear deformation, as well as the composition dependence, has been monitored and discussed.