Statistics of the catastrophic slip events in the Portevin-Le Chĝtelier effect

The statistics of catastrophic slip associated with discontinuous yielding (the Portevin-Le Chĝtelier effect) is investigated on an Al-Mg alloy. It is shown that a peaked distribution of stress drops changes towards a monotonic one, characterized by a power law with an exponent of -1.1, with increasing temperature and rate of straining. A model describing this behavior is studied, and it is suggested that there exists a formal similarity of the governing equations with those describing instabilities in frictional sliding. The use of discontinuous yielding in a tensile Al-Mg specimen is proposed as a candidate for modeling of earthquake statistics on a crustal fault.