Relation between structural disorder and fracture mechanisms in an Alkali borosilicate glass: A molecular dynamics study

Molecular dynamics simulations were implemented to model fracturing in simplified glasses representative of actual nuclear glasses. The application of a faster thermal quenching algorithm allowed us to simulate a disordered and depolymerized structure constituting a model of a glass irradiated by deposited nuclear energy. At the same time, Vickers indentation tests were performed to measure the fracture toughness of a glass specimen of the same composition that had received a large dose of elastic energy. Numerical calculations showed an increase in the plasticity of the more rapidly quenched glass that can be attributed to a reduction in the average degree of polymerization of the glass, especially around boron atoms. The increased plasticity delays crack propagation because a larger number of plastic dislocations is required. This observation at the scale of the glass nanostructure is proposed to account for the experimentally observed fracture toughness.