On measuring the fracture energy of model metallic glasses

We report a heuristic approach to measure the fracture energy of model metallic glasses using molecular dynamics simulation. Specifically, we adopted the Rivlin-Thomas method, simplified by Suo et al., which is applicable even with the presence of plastic flow. We further modified the testing condition with semi-rigid holders in our molecular simulations, to avoid unintended fracture near the holders. This method was first applied in measuring the fracture energy of a brittle model glass, which agrees well with direct K-IC and J(IC) measurements (both measurements are independent of the crack size). Furthermore, the fracture energy values of a family of model metallic glasses, ranging from brittle to ductile (BTD), were measured. The Poisson's ratio-fracture energy (nu-G, or nu-G/2 gamma, normalized by the surface energy) relation obtained here exhibits a BTD transition at a critical Poisson's ratio of 0.31-0.32, consistent with experimental results. Published by AIP Publishing.