Characterization of dynamic microstructural evolution of AA7150 aluminum alloy at high strain rate during hot deformation

The AA7150 aluminum alloy was compressed to various strains at strain rate of 10 s(-1) and temperatures of 300 degrees C and 450 degrees C, respectively. Flow stress behavior, substructure evolution, morphology and spatial distribution of precipitates were studied based on differential scanning calorimetry analysis and transmission electron microscope observation. The results showed that dynamic flow softening occurs during hot deformation. The main softening mechanism could be concluded as dynamic recovery at 300 degrees C and continuous dynamic recrystallization at 450 degrees C. The clear heterogeneous spatial distributions of precipitates are found during deformation and enhanced with increased strain. Higher contents of Cu in T phases are found at 450 degrees C than at 300 degrees C, which present a transformation process from T phases to S phases as well. The associated evidence of dynamic precipitation on dislocations and particle-stimulated nucleation, as well as the detailed microstructural inherited relationship and morphological texture (particles preferred orientation) were characterized.