Effect of hot-deformation on microstructure and mechanical properties of AZ80 magnesium alloy

In this study, the microstructure evolution of AZ80 magnesium alloy, in particular the precipitation mechanism of β Mg17Al12 phase, during hot deformation at different temperatures was characterized by SEM and the effect of the morphology of the β phase on tensile properties at room temperature was investigated. It was revealed that AZ80 cast ingot exhibited a net-work microstructure with the Mg17Al12 particles precipitating mainly in the vicinity of the grain boundaries. The net-work largely remained after the homogenization treatment. Hot-compression tests were carried out under a constant compressing speed of 8 mm/s in the temperature range 200–400 °C and an equivalent strain range 0.80–2.65. It was found that the net-work was destroyed during hot-compression and the following Mg17Al12 morphologies were observed depending on the hot-compression temperature and strain: strip, fine granular and lamellar. Hot-deformation has significantly improved the mechanical properties of the alloy due to refinement of grain size and change of Mg17Al12 morphology from net-work to favorable fine granular shape.