Effects of Al2O3 Particles on Grain Growth of AZ31 Magnesium Alloy at Elevated Temperatures by Phase Field Simulation

Abstract

We established a phase-field model to simulate the refinement effect of Al2O3 particles on the grain growth of AZ31 magnesium alloy at elevated temperatures during equal channel angular pressing (ECAP) process in realistic spatio-temporal scale. Simulations were performed to study the influences of fraction of Al2O3 particles and processing temperature ranging from 250°C. to 350°C. during ECAP. The simulation results agreed well with the limited existing experimental data for the ECAPed AZ31 alloy to prove the success of the model. The results showed that when the fraction of Al2O3 particles was larger, the grain size of the sample was smaller during ECAP. For instance, the grain size was reduced by 28.7% with the addition of 4 wt.% Al2O3 particles, compared with that of the alloy without the particles at 250°C. However, if the particle fraction is greater than 4 wt.%, further particle addition will have less effect. Moreover, it was also found that grain size owing to the Al2O3 addition decreased more significantly with processing temperature. For example, when the addition of Al2O3 particles was 2 wt.%, the grain size was reduced by 2.96μm at 250°C, 3.60μm at 300°C, and 5.19μm at 350°C, respectively; in contrast with that of the alloy without the particles.