Emergence of order from disorder in amorphous silica under extreme deformation

The mechanical behavior of glass has been a subject of active research for many decades. Yet the underlying mechanisms that govern crack nucleation and propagation in amorphous silica remains less understood. In this talk, we will present an atomistic scale understanding of the relative roles of Si and O atoms in governing the crack nucleation and propagation criteria at finite temperatures. Our results suggest that both crack nucleation and propagation are governed by chainlike nanoscale virial stress-fibers that form as a collection of regularly spaced atoms. They belong to a set of interacting tetrahedral structures comprising Si and O atoms, and they form and break continuously during the crack nucleation and propagation process. Additionally, the virial stress fields in the domain exhibit a highly heterogeneous and species-dependent structure at low deformation. However, with increased deformation, a set of ordered structure emerges prior to undergoing failure. This transition from disorder to order forms the physical foundation for complex deformation and fracture behavior of amorphous silica. The details of the atomistic process regulating the underlying mechanisms are undetectable from the macroscopic stress-strain data.