The morphology ofβ-Mg17Al12 phase and mechanical properties of as-cast AZ80 magnesium alloy after spheroidizing treatment were investigated by means of optical microscope（OM）

field emission scanning electron microscopy（FESEM）

X-ray diffraction（XRD）

hardness and tensile testing.The results reveal that the coarse divorced eutectic phase β-Mg17Al12 phase in the AZ80 cast magnesium alloy is fully dissolved into Mg matrix during isothermal process at 415℃

and the perlite-type lamellerβphase with dense structure is precipitated from magnesium solid solution during the slow cooling.And then

the spheroidizing treatment was carried out

and the lamellerβphase was spheroridized by dissolved themselves.With the increase of spheroidizing time

the lamellarβphase began to fusing to generate short rod firstly

then transform to spheroidization.After spheroidizing treatment at 320 ℃ for 16 h

lots of small granularβphases are distributed dispersedly in the magnesium matrix.However

when the spheroidizing time is further increased

dissolution of the granularβphase appears in the alloy

and the number ofβphase is reduced.And after spheroidizing treatment at 320℃ for 16 h

yield strength

tensile strength and elongation of AZ80 magnesium alloy reach 132.5MPa

252.4MPa and 9.56%

respectively.The brinell hardness of the alloy are increased firstly

and then declined with prolongation of spheroidizing time

however

the hardness value is higher than that of the as-cast alloy.