Dynamic recrystallization mechanisms and microstructure evolution of a novel Al-Zn-Mg-Cu-Zr alloy by isothermal compression
Mengjun Long, Feng Jiang, Yuanming Su, Zeyu Xiao
Abstract
The dynamic recrystallization (DRX) behavior and microstructure evolution of a novel Al-Zn-Mg-Cu-Zr alloy was investigated by isothermal compression tests at temperature of 350–470 °C and strain rate of 0.0001–1 s −1 . The results showed that the flow behavior revealed typical dynamic recovery (DRV) characteristics at a high strain rate (1 s −1 ), while exhibited a DRX shape when the strain rate decreased. The critical strains ( ε c ) of the DRX decreased with the decrease of strain rate or the increase of deformation temperature. A low temperature was conductive to precipitation behavior, the coarse precipitates and dispersed Al 3 Zr particles would pin the dislocations and substructures, which inhibit the DRX process. The DRX mechanism of the Al-Zn-Mg-Cu-Zr alloy was dominated by continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) during the hot deformation process, upon increasing the temperature and decreasing the strain rate, there was a transition point of DRX mechanism from DDRX to CDRX. Moreover, the linear relationship between the Zener-Hollomon (Z) parameter and DRX grain size was established for the further exploration of the transition of the dominant DRX mechanism.