Strengthening and toughening mechanisms of metallic glass nanocomposites via graphene nanoplatelets

Abstract

The lack of ductility, mainly due to shear localization, limits the full exploitation of metallic glasses (MGs). Such a weakness can be mitigated via introducing graphene nanoplatelets (GNs), which helps strengthen and toughen MG matrix. Using molecular dynamics simulations, we investigate the tensile deformation of Cu50Zr50 metallic glass-graphene nanoplatelet composites (MGGNCs) regarding the effects of graphene volume fraction and graphene layer number. Increasing fraction of GN in MGGNC enhances both tensile strength and fracture strain. The dominant component changes from MG matrix to GN, corresponding to a failure mode transition from shear banding in MG to brittle fracture in graphene. For a given volume fraction, single-layered GN behaves better than its double-layered counterpart, manifested as a higher fracture strain in MGGNCs. Our study illustrates the strengthening and toughening mechanisms in MGGNCs, and why single-layered GN performs better. All of these results can contribute to the synthesis of novel MG/graphene composites.