Change in crystallographic orientation distribution during superplastic deformation in an Al-Zn-Mg-Cu alloy

The change in crystallographic orientation distribution during superplastic deformation in an Al-Zn-Mg-Cu alloy has been investigated in order to reveal the deformation mechanism. The well-known strain rate dependence of the deformation behavior was examined by SEM/EBSP (scanning electron microscopy/electron back scatter diffraction pattern) analysis. Fraction of low angle grain boundaries increased after deformation at the high strain rate, presumably due to dislocation activity, while fraction of random boundaries was high in the specimen deformed at the low strain rate. Progressive randomization of the initial texture was also found during deformation at the low strain rate. Further, the intragranular misorientation, grain boundary misorientation and local orientation are analyzed in detail to discuss the accommodation process.