The effects of different contents of rare earth Er on the microstructure and properties of Al-7 Si-0.6 Mg aluminum alloy were investigated by scanning electron microscopy（SEM）

energy dispersive spectrometer（EDS）

X-ray diffraction（XRD） and transmission electron microscopy（TEM）. The results indicate that the alloy is mainly composed of α-Al

eutectic Si

AlEr

2

Si

2

and iron-rich phases（π-AlSiMgFe and β-AlSiFe）. Rare earth Er is an excellent modifier that can obviously improve the microstructure of Al-7 Si-0.6 Mg aluminum alloy. The addition of Er not only refines the primary α-Al phase in the alloy

but also modifies the eutectic silicon.When the addition of rare earth Er is 0.1%

the refinement and modification effect is desirable

where the primary phase α-Al dendrite spacing is decreased

the coarse dendrite is gradually refined

and the eutectic Si is evolved from acicular to short rod. Compared with the one without rare earth addition

the hardness of the alloy with 0.1% Er addition is increased by 23.2%

and the elongation and tensile strength reach 4% and 293 MPa

respectively.