On the similarity of plastic flow processes during smooth and jerky flow in dilute alloys

The jerky flow of dilute alloys, or the Portevin-Le Chatelier effect, has a burst-like intermittent character at different fluctuation size levels. Multifractal analysis is applied to both the macroscopic stress serrations and the acoustic emission accompanying the plastic deformation. Multifractal scaling is found for both kinds of time series. The scaling range of the stress serrations is limited from below by their characteristic frequency. Unexpectedly, the scaling range for acoustic bursts not only covers this range but spreads to much shorter time scales with the same scaling exponent. This result testifies that the deformation processes revealed by the acoustic emission at a mesoscopic scale have a similar nature during both stress serrations and smooth plastic flow. The implications on the crossovers in the dynamics of jerky flow are discussed.