Effect of superplastic deformation on microstructures, texture, and mechanical properties of 2A97 Al–Cu–Li alloy

Abstract

In the present study, the effect that superplastic deformation exerts on the microstructures, texture, and mechanical properties in 2A97 Al–Cu–Li alloy was investigated. The as-received material was deformed to a series of strains for 50%, 100%, 150%, and 200% at 430 °C with an initial strain rate of 2 × 10−3 s−1, and the grain structure, dislocation, secondary phase particles, cavities, texture, and tensile properties of deformed alloys were demonstrated and discussed comprehensively. Results show that with the increase of superplastic strain, the grain size of the alloy decreased gradually due to the dynamic recrystallization, and the Cu-rich secondary phase particles partially dissolved and partially coarsened. The initiation and growth of the cavities mainly depended on the grain boundary sliding and grain rotation, the fraction of cavities increased rapidly at higher strains (100%–200%). Superplastic deformation weakened the rolling texture (Brass, Copper, and S) and enhanced the recrystallization texture (Goss and ND-Rotated-Cube). The strength of the material decreased with increasing the superplastic strain firstly, after the strain exceeded 100%, the strength started to increase. The fracture elongation varied oppositely. The strengthening mechanism was discussed in detail. The coarsening of Cu-rich secondary phase particles and the rapid formation of cavities resulted in the drastic loss in ductility after the strain of 100%.