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Mg-5Li-5Al-3Zn-xCd(x=0,2,3,4,5) alloys were prepared. The densities of these alloys were measured with Archimedes' method. The influence of Cd element on the microstructure and the properties of these alloys were also studied. The results indicate that these alloys possess low density ranging from 1.5 to 1.7 g·cm^-3. The addition of Cd has the refining effect on the α-Mg phase and causes the formation of Mg₃Cd intermetallic compound. The refinement and the formation of Mg₃Cd improve the mechanical properties of alloys. When the Cd content is 3 wt.%, the tensile strength of alloy reaches its peak value(288 MPa).

Microstructural characterization of as-cast and extruded experimental alloys as (A) Mg-6.86Li-3.02Al-1.12Ce-0.7Ca (B) Mg-8.15Li-3.07Al-1.12Ce-0.72Ca (C) Mg-10.54Li-3.54Al-1.23Ce-0.94Ca are researched in this paper. The results show that the as-cast specimens of (A) and (B) are composed of α (Mg) phase, β (Li) phase, rod-like and bulk Al₂Ce compound. On the other hand, β phase (Li), bulk and rod-like Al₂Ce compound, Al²Ca compound at boundaries are observed in the as-cast (C) alloy. The addition of Ce and Ca also shows in the microstructure the presence of Al-Ce-Ca phase, a solid solution of Ca in Al2Ce compound. In the extruding alloys, the microstructure is refined and the β phase has the effect of coordination during deformation. The long rod-like and the bulk compounds become short rods and fine clumps distributing evenly in the extruding direction after extruding process. The microstructure of extruded Mg-10.54Li-3.54Al-1.23Ce-0.94Ca alloy testified the existence of eutectic structure.