Crossover in the scale-free statistics of acoustic emission associated with the Portevin-Le Chatelier instability
Résumé
The acoustic emission accompanying plastic deformation obeys scale-free statistics reflecting avalanche-like dis-location motion. This feature holds out for the macroscopically unstable deformation of alloys. However, stress serrations display peaked distributions at low enough strain rates. This occurrence of a characteristic macroscopic scale was supposed to result from the synchronization of dislocation avalanches. In the present work, the synchronization mechanism is studied using statistical analysis of different subsets of acoustic events. A crossover in the power-law exponents is detected for the events occurring during deep stress drops. It is ascribed to a transition from chaining to overlapping dislocation avalanches.
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2018_Crossover in the scale-free statistics of acoustic emission associated with the Portevin-Le Chatelier instability_LEBEDKINA.pdf (335.45 Ko)
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