Fracture surface energy and toughness of inorganic glasses

A simple model is proposed to predict the fracture surface energy (gamma) and the fracture toughness (K-IC) of glasses from their nominal compositions. The theoretical values are compared with the experimental ones, as obtained by means of self-consistent methods such as the Single Edge Pre-crack Beam (SEPB) and Chevron Notch (CN) ones, when available. A remarkable agreement is observed for ionocovalent glasses. This corroborates previous investigations showing that crack tip is nearly atomically sharp. In the case of metallic glasses, the theoretical values are much smaller than the experimental ones, which support the occurrence of crack tip plasticity and shielding effect. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.