The binary Mg-Zn alloys with varied Zn content（ 2

4

6

8

10 and 15

in weight） were prepared

and microstructure and mechanical properties of the as-cast Mg-x Zn alloys were investigated by using an optical microscope（ OM）

X-ray diffractometer（ XRD）

scanning electron microscope（ SEM） and mechanical testing.The results reveal that as-cast microstructure of the alloys is composed of matrix α-Mg and eutectic phases distributed along grain boundaries. With increasing in Zn content

the morphology of eutectic phase is gradually changed from isolated particles into fully continuous net-work structure

and the grain sizes are decreased. In addition

the tensile strength and elongation of the alloys are increased firstly

and then decreased gradually. The elongation of the alloy with 4% Zn reaches maximum value of 10. 78%

while ultimate tensile strength reaches210 MPa in the 6% Zn-containing alloy. With the increase of Zn content

the fracture behavior of the alloys is changed from quasi-cleavage to cleavage fracture.