Activity-Induced Annealing leads to Ductile-to-Brittle Transition in Amorphous Solids

TL;DR

This paper demonstrates that activity-induced annealing can control the failure mode of amorphous solids, enabling a transition from ductile to brittle behavior through novel in silico processing techniques.

Contribution

It introduces a new method of activity-induced annealing to produce well-annealed glasses and explores its effects on failure modes and shear band formation.

Findings

Active annealing induces ductile-to-brittle transition.

Surface relaxation is enhanced by activity in open boundary conditions.

Aspect ratio influences shear band formation and failure mode.

Abstract

Investigating the behavior of amorphous solids under various external loading conditions continues to be an intriguing area of research with significant practical implications. In this study, we demonstrate the utilization of self-motility as a means to anneal glasses and use that as a means to fine-tune the failure mode of the system under uniaxial tensile deformation. We begin by highlighting the annealing effects of activity and draw parallels with other well-known mechanical annealing processes, such as oscillatory shearing (both uni- and multi-directional). Furthermore, we explore the annealing effects in the presence of open boundaries, observing enhanced surface relaxations due to activity. By implementing various activity-induced annealing protocols, we successfully induce a transition in the failure mode from ductile to brittle. This is demonstrated via performing tensile tests on the glass samples resulting from the active-annealing process. The intricate effects of geometry on the formation of shear bands are also examined. We find that samples having an aspect ratio greater than one fail via shear band formation, owing to their formation angle of $45\degree$ from the strain axis. In conclusion, we introduce a novel method for producing well-annealed glasses in silico and establish a correspondence between sheared and actively driven glasses.