Microstructure and Kinetics of β-Mg17Al12 Phase Transformation for Warm Rolled AZ91 Magnesium Alloy

The microstructure and the kinetics of beta-Mg17Al12 phase transformation during annealing process for warm-rolled AZ91 magnesium alloy were investigated. The results showed that few twins were found in solid state AZ91 magnesium alloy after warm rolling, which provides energy for beta-Mg17Al12 particles to nucleate and growth; the beta-Mg17Al12 particles were prior to form at alpha-Mg, twin grains boundary and especially the place of high energy; by the annealing time extending, the quantity of beta-Mg17Al12 particles increased. And combined with the experimental data and the JMAK equation, the fitting equation of Kinetics of beta-Mg17Al12 phase transformation was built. During annealing process, the twin grains disappeared and the original bulky organization was replaced by recrystallization grain, while the grain refinement was obvious with the grain reduction to 20-60 mu m.