Dynamic microstructural changes in Mg–9Al–1Zn alloy during hot compression

Twin dynamic recrystallization (DRX) occurs during the hot compression of AZ91 alloy with precipitation of Mg17Al12 phase at the newly formed DRXed grain boundaries. The pinning effect of the Mg17Al12 precipitates is greatly influenced by compression temperature, resulting in compression temperature having a stronger influence than strain rate on DRXed grain size. The conventional relationship between DRXed grain size and the Zener–Hollomon parameter breaks down as the pinning effect of the precipitates is not taken fully into consideration.