Shocking of metallic glass to induce microstructure heterogeneity: A molecular dynamics study

Surface severe plastic deformation (SSPD) has been demonstrated to improve the ductility of metallic glass. The physical interpretation, however, remains on the phenomenological level. In this study, a molecular dynamics (MD) simulation is carried out to elucidate the molecular mechanisms underlying the improvement in ductility. MD simulation reveals that shock waves resulting from SSPD can induce pre-deformed atoms, which are randomly embedded in the matrix of the metallic glass. The pre-deformed atoms have similar stress distribution and short-order structure as the matrix atoms, but with a larger atomic volume. When subjected to tensile or compressive stress, more shear bands are promoted by the pre-deformed atoms in the shock-treated sample as compared to the untreated one. The randomly distributed shear bands were found to experience more interactions, which delayed the catastrophic fracture, leading to increased ductility.