Self-induced marginality in plastically deformed crystals

TL;DR

This paper demonstrates that perfect crystals subjected to elastic instability exhibit quasi-brittle plastic yielding with self-induced marginal stability, akin to glassy materials, characterized by power-law avalanche statistics.

Contribution

It reveals that elastic instability in perfect crystals induces a quasi-amorphous state and self-organized criticality, bridging crystalline and glassy deformation behaviors.

Findings

Dislocation avalanches follow power-law distributions.

Pre- and post-yield avalanches have similar exponents.

Crystals exhibit marginal stability after elastic instability.

Abstract

Quasi-brittle plastic yielding is a salient feature of well-annealed glassy materials. Here we show that the same behavior is characteristic of perfect crystals after they experience mechanically driven elastic instability leading to massive nucleation of dislocations. We argue that such 'preparation' effectively converts an atomic configuration from crystalline to quasi-amorphous. To understand the nature of the subsequent intermittent mechanical response we study a model 2D crystal subjected to AQS driving and show that both pre- and post-yield dislocation avalanches exhibit power law statistics with similar exponents indicative of self-induced marginal stability.