Bridging necking and shear-banding mediated tensile failure in glasses

TL;DR

This study investigates the transition between necking and shear-banding failure modes in glasses through experiments and simulations, revealing how plasticity and cavitation influence failure patterns and cavity sizes.

Contribution

It provides a detailed analysis of the failure transition in glasses, linking macroscopic patterns to microscopic plasticity and cavitation dynamics, and highlights the importance of combined shear and dilation effects.

Findings

Failure transition occurs via a sequence of macroscopic patterns parametrized by tensile strength.

Largest cavity size depends nonmonotonically on temperature at fixed strain rate.

Cavity size scales with the cross-sectional area of the undeformed sample.

Abstract

The transition between necking-mediated tensile failure of glasses, at elevated temperatures and/or low strain-rates, and shear-banding-mediated tensile failure, at low temperatures and/or high strain-rates, is investigated using tensile experiments on metallic glasses and atomistic simulations. We experimentally and simulationally show that this transition occurs through a sequence of macroscopic failure patterns, parametrized by the ultimate tensile strength. Quantitatively analyzing the spatiotemporal dynamics preceding failure, using large scale atomistic simulations corroborated by experimental fractography, reveals how the collective evolution and mutual interaction of shear-driven plasticity and dilation-driven void formation (cavitation) control the various macroscopic failure modes. In particular, we find that at global failure, the size of the largest cavity in the loading direction exhibits a nonmonotonic dependence on the temperature at a fixed strain rate, which is rationalized in terms of the interplay between shear- and dilation-driven plasticity. We also find that the size of the largest cavity scales with the cross-sectional area of the undeformed sample. These results shed light on tensile failure of glasses, and highlight the need to develop elasto-plastic constitutive models of glasses incorporating both shear- and dilation-driven irreversible processes.