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

Abstract

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.