Mg-11Al-1.2Zn alloys containing 0.3% Sc were prepared by ingot metallurgy. The effects of scandium addition on the mechanical properties and microstructure of the as-cast alloy have been investigated by X-ray diffraction（XRD）

optical microscope（OM）

scanning electron microscope （SEM） and tensile testing. The results indicate that the microstructure of the alloys is mainly composed of primary α-Mg phase

Mg17Al12 phase and MgAlSc phase

in which the grain size and morphology and distribution of Mg17Al12 phase can be evidently improved with Sc addition. In addition

the tensile strength of the alloy at room temperature can be increased by more than 10% with the Sc addition.