Crossover in the dynamics of Portevin–Le Chatelier effect from chaos to SOC

We demonstrate the existence of a crossover in the dynamics of the PLC effect from chaotic to self-organized critical nature by analysing the stress–strain curves obtained from single crystals of Al–10%Cu subjected to three levels of constant strain rate deformation. At the lowest and intermediate strain rates, we provide an unambiguous support for the existence of a chaotic regime. For these two strain rates, the distributions of stress drops are peaked. At the highest strain rate, we find that the distributions of stress drops and their durations exhibit a power law behaviour reminiscent of a self-organized critical state. We also show that scaling relations are obeyed by the various exponents.