Investigation of Portevin-Le Chatelier effect in rolled α-phase Mg-Li alloy during tensile and compressive deformation

Avoiding the Portevin-Le Chatelier (PLC) effect is very important concern for wrought Mg-Li alloys. In this study, the special PLC effect was found in rolled Mg-5Li-3Al-2Zn (LAZ532) alloy during tensile and compressive deformation. By observing microstructure evolution of the alloy during tensile and compressive deformation, it was found that prismatic < a > and pyramidal < c + a > slips were activated during tensile deformation, resulting in plenty of dislocation accumulation. In the deformation process after compressive yielding, the deformations in coarse grains and fine grains were dominated by {10 (1) over bar 2} extension twinning and grain boundary slip, respectively. Based on experimental result analysis, the sudden appearance of PLC effect in the later stage of axial tensile deformation (along rolled direction) was caused by interaction between solute atoms and dislocations. In the process of axial compressive deformation (along rolled direction), PLC effect presented the complex and changeable phenomenon of appeared-disappeared-appeared, which was mainly caused by the continuous nucleation of twin in the material, the activation of grain boundary slip and the shear deformation of twin, respectively. (C) 2020 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.