Deformation behavior and dynamic recrystallization of a Mg–Zn–Y–Zr alloy

Dynamic recrystallization (DRX) of Mg–Zn–Y–Zr alloy had been investigated using hot compression test. It was studied that the onset of DRX process occurred before the peak of the stress–strain flow curves. The critical condition of the onset of DRX process was following as ((∂/∂σ)(−∂θ/∂σ)) = 0. The microstructure evolution of the alloy during the hot compression at various temperatures and strain rates had been studied. It suggested that the conventional DRX, i.e. the bulging out of part of the serrated grain boundaries firstly occurred on the original boundaries during the hot compression at 623 K. As further deformation was carried out, the continuous DRX had occurred inside the original grains. As the testing temperature increased, the DRX grain size became larger and larger. It is due to that the high temperature improved the migration of DRX grains boundaries. With increasing strain rate, the DRX grain size for the alloy deformed at the same strain became smaller and smaller. It is due to that the dislocation density of the alloy at high strain rate was higher. Finer subgrains and DRX grains were formed and more dislocations were absorbed into high-angle boundaries in the alloy deformed at high strain rate.