Microstructural Characterization of an Al-Mg-Si Aluminum Alloy Processed by Equal Channel Angular Pressing

摘要

In the present work,a peak-aged 6061 Al-Mg-Si aluminum alloy was subjected to equal channel angular pressing (ECAP) at 110 °C.The microstructure of the sample was characterized by high-resolution transmission electron microscope and weak-beam dark-field method.It was shown that the dislocation density in some local areas is much lower than the average dislocation density expected in the usual alloys processed by severe plastic deformation.High-resolution transmission electron microscope observations indicated that many full dislocations were dissociated into partial dislocations connected by stacking faults.In addition,a Z-shaped defect (i.e.,a type of dislocation locks) probably formed by the reactions of the partials in different {111} planes was first observed in the ECAPed alloy.Furthermore,the precipitation behavior and sequence in the present ECAPed sample were identified by high-resolution transmission electron microscopy.