Constitutive behavior of AZ80 M magnesium alloy compressed at elevated temperature and containing a small fraction of liquid

The constitutive behavior of AZ80 M magnesium alloy was investigated by using compression tests performed at the elevated temperature (400-470 degrees C) and in the semi-solid state containing a small fraction of liquid with different strain rates (0.001-0.1 s(-1)), and the microstructure evolution was observed. Considering the influence of liquid phase, a more reasonable constitutive model to describe the peak stress both at the elevated temperature range and in the semi-solid state was obtained. It can be divided into two types: plastic deformation when the alloy is in the solid state (400-470 degrees C); thixotropic deformation when the alloy is in the semi-solid state (above 520 degrees C). The average relative errors between the experimental and calculated values are 2.1% and 2.6%, respectively. The activation energy (Q) in the semi-solid state is 289 kJ/mol, which is higher than in the elevated temperature. It is suggested that the presence of liquid phase causes the deformation mechanism in the semisolid state obviously different from that at elevated temperature.