Abstract The microstructure, tensile properties and creep behavior of Mg–4Al–2Sn (AT42) and Mg–4Al–2Sn–1Ca (ATX421) alloy produced by ingot and die-cast were investigated. The die-cast alloy exhibits superior yield and tensile properties at room temperature and 200 °C. The strengthening mechanism of die-cast alloys was mainly attributed to the grain refinement and fine morphology of intermetallic phases. The die-cast ATX421 alloy exhibited the best creep resistance, i.e. the lowest minimum creep rate and the longest creep rupture time, while the poorest creep resistance was observed in the ingot cast AT42 alloy.