Fracture of silicate glasses: Microcavities and correlations between atomic-level properties

We use large-scale simulations to investigate the dynamic fracture of silica and sodium-silicate glasses under uniaxial tension. The stress-strain curves demonstrate that glass is brittle whereas rich in Na show pronounced ductility. A strong composition dependence also seen crack velocity which, for strain rate considered, on order 1800 m/s with low concentration decreases 650 if high. find during Na-rich very irregular cavities as large 3--4 nm form ahead front, indicating presence nanoductility these glasses. Before occurs, local composition, structure, mechanical properties are heterogeneous space a applied strain. Further analysis correlations between allows obtain better microscopic understanding deformation oxide how heating close tip, up several hundred degrees, permits structure relax.