Mg-Zn-Sn alloys with different contents of Zn and Sn at a total amount of 10% were prepared by metal molds

and the as-cast structure

especially the non-equilibrium eutectic structure and the mechanical properties of the alloys were investigated.The results show that the as-cast structure of Mg-Zn-Sn alloys is composed ofα-Mg

MgZn and（or）Mg

2

Sn.Lamellar eutectic phases can be generated in the Mg-Zn-9Sn with high Sn content and Mg-9Zn-Sn alloys with high Zn content.The eutecticβphases（MgZn and Mg

2

Sn）in Mg-5Zn-5Sn alloys with the same content of Zn and Sn are uniformly distributed in the grain boundary in form of small blocks and the morphology of the eutectic phases is presented almost all divorced structures.The volume fraction of the non-equilibrium eutectic was calculated by the Schiel equation.The eutectic fraction of Mg-9Zn-Sn alloys with 9% Zn content is as high as 14%

and the eutectic structure almost all presents a lamellar structure.The experimental results of mechanical properties show that the Mg-5Zn-5Sn alloys has the desirable comprehensive mechanical properties.In addition

according to the test results of the solid solution amount of Zn and Sn atoms in magnesium matrix

the strength and toughness of alloys were further analyzed.