The hidden order behind jerky flow
Résumé
Jerky flow, or the Portevin-Le Chatelier effect, is investigated at room temperature by applying statistical, multifractal and dynamical analyses to the unstable plastic flow of polycrystalline Al-Mg alloys with different initial microstructures. It is shown that a chaotic regime is found at medium strain rates, whereas a self-organized critical dynamics is found at high strain rates. The crossover between these two regimes is signified by a large spread in the multifractal spectrum. Possible mechanisms leading to this wealth of patterning behavior and their dependence on the strain rate and the initial microstructure are discussed.