Toward revealing full atomic picture of nanoindentation deformation mechanisms in Li2O-2SiO2 glass-ceramics

Obtaining full understanding of deformation mechanisms in Li2O-2SiO(2) glass-ceramics subjected to sharp contact loading is a pressing need for many industrial applications. We herein conduct systematic molecular dynamics simulations to reveal atomic details that are otherwise extremely challenging to probe experimentally. Our study shows that glass-ceramics exhibit a dramatically different plastic deformation map compared to glass, where the nanocrystalline phase dictates the plastic zone shape. Shear flow preferentially nucleates and travels along the interfaces before moving to the surrounding glass and nanocrystals. Dislocations, amorphization zones around the indenter, and shear flow at glass and crystal interfaces help to dissipate contact energy and deconcentrate the deformation, thereby increasing fracture toughness and discouraging the development of catastrophic cracks. Additionally, extensive discussions on the effect of LS2 nanocrystal aspect ratio, location and orientation with respect to indenter in shaping the plastic zone also help to establish a solid knowledge in understanding surface damage behaviors of glass-ceramics as observed in many real applications. (C) 2021 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Automated summary

Glass-ceramics exhibit a significantly different plastic deformation behavior under sharp contact loading compared to glasses, with nanocrystalline phase dictating the shape of the plastic zone. Shear flow primarily nucleates and propagates along interfaces before transferring to surrounding glass and nanocrystals, contributing to energy dissipation and deformation deconcentration, and ultimately enhancing fracture toughness and inhibiting catastrophic crack propagation. Extensive discussions on LS2 nanocrystal aspect ratio, location, and orientation with respect to the indenter provide insights into surface damage behaviors of glass-ceramics in real applications.