Flow stress behavior and processing map of extruded 7075Al/SiC particle reinforced composite prepared by spray deposition during hot compression

Hot compression tests of the extruded 7075Al/15% SiC (volume fraction) particle reinforced composite prepared by spray deposition were performed on Gleeble-1500 system in the temperature range of 300-450 degrees C and strain rate range of 0.001(-1) s(-1). The results indicate that the true stress-true strain curve almost exhibits rapid flow softening phenomenon without an obvious work hardening, and the stress decreases with increasing temperature and decreasing strain rate. Moreover, the stress levels are higher at temperature below 400 degrees C but lower at 450 degrees C compared with the spray deposited 7075Al alloy. Superplastic deformation characteristics are found at temperature of 450 degrees C and strain rate range of 0.001-0.1 s(-1) with corresponding strain rate sensitivity of 0.72. The optimum parameters of hot working are determined to be temperature of 430-450 degrees C and strain rate of 0.001-0.05 s(-1) based on processing map and optical microstructural observation.