Grain growth in AZ31 Mg alloy during recrystallization at different temperatures by phase field simulation

In order to accomplish the quantitative simulation of the realistic spatio-temporal microstructure evolution during recrystallization in the industrial application scale of micrometers and minutes, a model has been established using the phase field method (PFM). All the physical values of the parameters in the model have been determined by establishing a set of rules, some of which are proposed in first time. The simulated results have a good agreement with the experimental observations of the AZ31 Mg alloy during recrystallization between temperatures 300-400 °C for up to 100 min. The simulation implies a mechanism variation in the activity energy of grain boundary mobility at low temperatures such as at 250 °C for the alloy. Analysis of the simulated microstructures reveals that the grain size fluctuation increases with increasing recrystallization temperature and annealing time. It is found that the grain size fluctuation becomes particularly severe when the recrystallization temperature is over a critical value of 350 °C, which agrees well with the existing experimental data in the AZ31 Mg alloy.