Regular Article

Effects of orientation and pre-deformation on velocity profiles of dislocation avalanches in gold microcrystals^★

Department of Materials Science and Engineering and Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA

^a e-mail: rmaass@illinois.edu

Received: 3 October 2018
Received in final form: 20 November 2018
Published online: 16 January 2019

Abstract

We report on the spatiotemporal dynamics of dislocation avalanches (crystallographic slip) in gold microcrystals with different orientations and also different initial dislocation densities. It is found that the size-integrated averaged velocity profiles have both orientation-dependent and initial-microstructure-dependent peak velocities and velocity decays. With increasing symmetry and apparent strain-hardening rate, the peak velocities decrease and the velocity of the average shape profile decays more slowly with time. These experimental results indicate the material-specific nature of collective dislocation rearrangements that underlie slip events with a net magnitude of a few to several hundred Burgers vectors in the studied microcrystals. Furthermore, we point toward sensitivity to filtering details that may significantly affect conclusions when comparing experiment with theory.