Effect of equal channel angular pressing on the Portevin-Le Chatelier effect in an Al3Mg alloy

Plastic deformation of alloys is often accompanied with discontinuous flow known as the Portevin-Le Chatelier (PLC) instability. Recent studies of mechanical behavior of alloys subjected to severe plastic deformation (SPD) revealed different forms this phenomenon can take as a result of grain refinement. In the present work, it is reported that SPD may effectively suppress the macroscopic stress serrations characteristic of the PLC effect. At the same time, small-scale stress fluctuations can still be resolved on the deformation curves. To investigate their nature, stress vs time curves for an Al3Mg alloy processed by equal channel angular pressing (ECAP) are compared with those obtained for the initial coarse-grained (CG) material, using statistical and multifractal approaches to multi-scale analysis of time series. An interpretation of the results in terms of the concurrency of phenomena of self-organized criticality and synchronization in the dislocation system is proposed.