Critical dynamics of burst instabilities in the Portevin-Le Ch atelier effect.
We investigate the Portevin-Le Châtelier effect (PLC), by compressing Al-Mg alloys in a very large deformation range, and interpret the results from the viewpoint of phase transitions and critical phenomena. The system undergoes two dynamical phase transitions between intermittent (or "jerky") and "laminar" plastic dynamic phases. Near these two dynamic critical points, the order parameter 1/tau of the PLC effect exhibits large fluctuations, and "critical slowing down" (i.e., the number tau of bursts, or plastic instabilities, per unit time slows down considerably).
D'Anna
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Institut de Génie Atomique, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland.
Nori
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