INVESTIGATION OF PORTEVIN-LE CHATELIER EFFECT IN COARSE-GRAINED Al-Mg ALLOYS

The behavior of deformation bands associated with the Portevin-Le Chatelier (PLC) effect was studied in an Al-Mg alloy. The microstructure of the alloy consisted of coarse grains with approximately equiaxed shape and average size of 40 mu m. A series of tensile tests was carried out at room temperature and initial strain rates of 1 x10(-3) s(-1) and 5x10(-3) s(-1). Comparing different propagation characteristics of the PLC bands (the velocity of the PLC band propagation, the local strain rate within the band, the band width, and the angle of band) for the model coarse-grained alloy reveals numerous unusual features of spatiotemporal behavior observed at various stages of strain hardening the alloy. The specific mechanisms of plastic deformation at various stages of strain hardening are considered in some detail.