Effects of solution treatment on microstructure of as-aged AZ80 magnesium alloy have been observed by OM（optical microscope）

XRD（x-ray diffraction）and SEM（scanning electron microscope）.The results show that the microstructure has the important effects on precipitate mode

number and morphology of β-Mg17Al12 phase with aging at 200 ℃ after different solid-solution treatment.The discontinuous precipitation is dominated in precipitate

and major precipitate occurs in the incomplete solution alloy with aging for 4 hours.With aging for 12 hours

the continuous precipitation is dominated in the complete solution alloy

which can restrain the nucleation and growth of discontinuous precipitates at grain boundary

while the precipitates in the incomplete solution alloy are still controlled by discontinuous precipitation

in which partial precipitates invade into α-Mg phase.