Hot deformation behavior and processing map of in-situ nano ZrB₂ reinforced AA6111 matrix composites

Hot deformation behavior of in situ 2 vol. % nano ZrB₂/AA6111 composites was researched in the deformation temperature range from 300 °C to 450 °C and the strain rate from 0.01 s⁻¹ to 10 s⁻¹. The experimental result indicated that the flow stress decreased with decreasing strain rate and increasing temperature, and the flow curves showed a rising trend and significant fluctuation after the stable stage. Constitutive equation can be established by the prediction of materials constants. The processing map based on the dynamic materials model (DMM) exhibited two deterministic domains, domain A (320 °C–360 °C/0.17–1.2 s⁻¹) and domain B (430 °C–460 °C/0.13–1.1 s⁻¹). According to the processing map and microstructure observation, the optimum processing windows for AA6111 matrix composites was determined to be domain B (430 °C–460 °C/0.13–1.1 s⁻¹). It was also founded that the particle clusters promote the Dynamic Recrystallization (DRX) but prevent the grain growth and reduce the recrystallization grain size, which caused the high DRX temperature and was beneficial to the high temperature performance of composites. (paper)