Critical behavior and size dependence in dislocation plasticity

TL;DR

This paper shows that size-dependent plasticity and strain bursts in microcrystals are manifestations of underlying collective dislocation dynamics, consistent across simulations and experiments, and not due to different physical mechanisms.

Contribution

It demonstrates that size effects and strain bursts are linked to collective dislocation phenomena, unifying understanding across scales and sample sizes.

Findings

Agreement between 2D and 3D dislocation simulations and experiments

Size effects arise from finite-size scaling of dislocation dynamics

Peculiarities of small-sample plasticity are due to collective behavior

Abstract

Microcrystals deform very differently from their macroscopic counterparts, displaying a size-dependent yield stress and intermittent plastic strain bursts. Here we demonstrate that size effects and strain bursts may be just two different signatures of fundamental collective phenomena that govern the dynamics of dislocation systems on all scales. We confirm this conjecture by demonstrating agreement between the results of 2D and 3D dislocation dynamics simulations and experimental results on compressed micropillars. Our results indicate that many peculiarities of small-sample plasticity may arise from the finite-size scaling properties of collective dislocation dynamics, rather than from changes in the physical mechanisms governing dislocation motion.