Changes in Crystallographic Orientation Distribution during Superplastic Deformation in Aluminum Alloys

Abstract

Changes in crystallographic orientation distribution during superplastic deformation in a fine-grained Al-Zn-Mg-Cu alloy and an Al-Mg-Mn alloy consisting of the coarse-grained surface and the fine-grained center layers have been reviewed in order to reveal contribution of dislocation slips to deformation. The strain rate and grain size dependences of the deformation behavior were examined by SEM/EBSD (scanning electron microscopy/ electron back scatter diffraction) analysis. Intragranular misorientation increases after deformation at high strain rates, presumably due to dislocation activity, while it was low in the specimen deformed at a low strain rate in the early stage of 35% strain. Progressive randomization of the initial texture was also found during deformation at the low strain rate. Further, grain structure and grain boundary character are analyzed in detail to discuss the deformation mechanism.