Effect of asymmetrical deformation on the microstructure evolution of semisolid AZ91D alloy

The effect of asymmetrical deformation on the microstructure evolution of semisolid AZ91D magnesium alloy manufactured by strain-induced melt activation (SIMA) process was investigated. The specimens were compressed at 230 °C, and then were isothermally held at the temperature of 560 °C for different times. At the isothermal holding stage, recrystallization and liquid phase nucleation occurs in the severe deformed region. And the liquid nuclei grow up rapidly to connect together. At different deformed areas liquid forms in different places. With the passage of time, solid fraction decreases, while solid particle size increases in all parts. The variational speed varies from area to area. After isothermal holding for 20 min, the effect of asymmetrical deformation is small, and homogeneous and appropriate microstructure of a semisolid is obtained in the experiment.