Revealing the deformation zone in oxide glasses using in situ X-ray nanodiffraction

Conventional indentation studies primarily focus on the surface deformation, largely ignoring the sub-surface events in the process. The deformation zone formed locally in the sub-surface during indentation of oxide glasses, typically contains elastic strain, densification, and shear flow; all of which are governed by the glass structure, stress state, defect concentration, and are thereby subject to variations in glass composition and processing history. In this study, we probe the glass densification in situ during indentation from the medium-range structure in different oxide glasses, utilizing X-ray nanobeam-induced scattering. We find varying deformation zones in terms of shape, size, and the relative contribution between densification and shear flow over different indentation loads for different glass compositions of varying Poisson’s ratios. Probing the glasses’ deformation zone at a high spatial resolution down to 100 nm reveals important structural insights into the mechanical behavior, thereby aiding the understanding and design of more damage-resistant glasses.