Preparation of lanthanum-containing AE heat resisting die-casting magnesium alloy

The invention relates to a lanthanum contained AE series heat-resistant die-casting magnesium alloy and a preparation method thereof. The alloy consists of the following compositions by mass percentage: 3.5 to 4.5 percent of Al, 1 to 6 percent of La, 0.2 to 0.6 percent of Mn, and less than 0.03 percent of gross of impurity elements Fe, Cu and Ni, and the balance being magnesium. The method comprises the following steps: preheating pure magnesium, aluminum, aluminum-manganese interalloy and magnesium-lanthanum interalloy to the temperature of 200 DEG C according to a proportion; then, putting the mixture into a crucible which is preheated to the temperature of 300 DEG C, and introducing shield gas with a volume ratio of SF6 to CO2 being 1:100; adding the magnesium-lanthanum interalloy into the crucible after melt reaching a temperature of between 720 and 740 DEG C; continuously introducing the shield gas to stir the melt for 5 to 10 minutes; introducing argon gas to refine the melt for 5 to 10 minutes; and keeping the mixture stand for 28 to 32 minutes to obtain the lanthanum contained AE series heat-resistant die-casting magnesium alloy. The alloy has tensile strength at 200 DEG C of between 119 and 136MPa, yield strength of between 85 and 107MPa, elongation percentage of between 18 and 24 percent, and creep rate under 70MPa at 200 DEG C of 1.17*10 s .