Microstructure and texture evolution during superplastic deformation of 7475 Al alloy

Various microstructural characteristics of superplasticity in a 7475 aluminum alloy are evaluated. The microstructure evolution in the process of superplastic deformation (SPD) is characterized by X-ray texture measurements and the EBSD technique. The specimens were pulled in tension at the initial strain rate of 5.6x10(-4)s(-1) after the holding time of 1800 seconds at 803 K. The major texture component in as-prepared 7475 aluminum alloys is a Cube {001}<100> texture. The intensity of the Cube texture and other texture components is decreased and grain orientations become more random after superplastic elongation. However, the evolution of the Brass {011}<112> component and the increase in percentage of the coincidence site lattice boundaries fraction shows that the mechanism in the initial stage of SPD may be governed by crystallographic slip. Details of the SPD process are discussed for different strains at a given pulling speed and for different pulling speeds at a given strain.