On the similarity of plastic flow processes during smooth and jerky flow: Statistical analysis

Jerky flow in dilute alloys, or the Portevin-Le Chatelier effect, is investigated using statistical analysis of time series characterizing the evolution of the plastic activity at distinct scales of observation, namely, the macroscopic scale of stress serrations and a mesoscopic scale pertaining to the accompanying acoustic emission. Whereas the stress serrations display various types of statistical distributions depending on the driving strain rate, including power-law, peaked and bimodal histograms, it is found that acoustic emission is characterized by power-law statistics of event size in all experimental conditions. The latter reflect intermittency and self-organization of plastic activity at a mesoscopic scale. This shift in the observed dynamics when the observation length scale is decreased is discussed in terms of the synchronization of small-scale events. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.