The microstructure and mechanical properties of as cast and different heat treated Mg–2·6Sm–1·3Gd–0·6Zn–0·5Zr (wt-) alloy were investigated. The alloy in the as cast state is mainly composed of α-Mg matrix and (Mg,Zn)3(Sm,Gd)1 eutectic compounds. After solution treatment at 510°C for 4 h, the eutectic compound dissolved into the matrix completely. A good combination of tensile strength and ductility was obtained when the alloy was aged at 200°C for 32 h; the ultimate tensile strength, yield strength and elongation are 282 MPa, 185 MPa and 6·1 respectively. Precipitation strengthening is the largest contributor to strength (∼67) in 200°C peak aged alloy, which is related to plate shaped precipitate phases formed on prismatic planes of the α-Mg matrix.
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