Yield point of metallic glass

Shimizu, Futoshi ; Ogata, Shigenobu*; Li, J.*

Shear bands form in most bulk metallic glasses (BMGs) within a narrowrange of uniaxial strain . We proposethis critical condition corresponds to embryonic shear band (ESB)propagation, not its nucleation. To propagate an embryonic shearband, the far-field shear stress must exceed the quasi steady-state glue traction of shear-alienated glass until the glass-transition temperature is approached internally due to frictional heating, atwhich point ESB matures as a runaway shear crack. The incubationlengthscale necessary for this maturation is estimatedto be nm for Zr-based BMGs, below which size sample-scaleshear localization does not happen. In shear-alienated glass, the lastresistance against localized shearing comes from extremely fastdownhill dissipative dynamics (DDD) of timescale comparable to atomicvibrations, allowing molecular dynamics (MD) simulations to capturethis recovery process which governs . We model4 metallic glasses: a binary Lennard-Jones system, two binaryembedded-atom (EAM) potential systems, and a quinternary EAMsystem. Despite vast differences in the structure and interatomicinteractions, the four MD calculations give predictions of and respectively.