On nucleation and propagation of PLC bands in an Al–3Mg alloy

The processes of nucleation and propagation of Portevin–LeChatelier deformation bands during tensile deformation of the alloy AA5754 have been investigated by a special optical technique for local strain measurements, combining both a line-scan and a CMOS camera to record the changes of surface strain, applying digital image correlation. Examples for bands of types A and B are observed and discussed with respect to the micro-mechanisms of their nucleation and propagation, emphasizing local stress concentrations in addition to the well-known effects of dynamic strain aging and dislocation interactions for explaining the PLC behavior. Finally the nucleation and propagation of PLC bands are simulated by computations based on a simple constitutive model.