Investigation of Portevin-Le Chatelier Effect in Al-2.5 pct Mg Alloy with Different Microstructure

An experimental study is presented on the effect of microstructure change on the Portevin-Le Chatelier (PLC) effect of Al-2.5 pct Mg alloy. Tensile tests are performed on as-received and heat-treated [at 673 K (400 A degrees C) for 16 hours] samples for a wide range of strain rates. The serrations observed in the stress-time curves are investigated on statistical analysis point of view. The microstructures of the samples are characterized by optical metallography, X-ray diffraction, and electrical resistivity measurements. It is found that the excess vacancies generated due to heat treatment have an effect on the PLC phenomenon, which leads to a decrease in the strain rate sensitivity and an increase in the number of stress drop occurrences per unit time. The microstructural parameters like domain size and dislocation density have no appreciable effect on the PLC effect as far as the statistical behaviors of the serrations are considered. DOI: 10.1007/s11661-013-1630-1 (C) The Minerals, Metals & Materials Society and ASM International 2013