Yttrium-rich rare earth high-strength heat-resistant creep-resistant die-casting magnesium alloy

The invention relates to an yttrium-rich rare earth high-strength heat-resistant creep-resistant die casting magnesium alloy. Aiming at the problems that the prior AZ91 magnesium alloy has lower strength, low high-temperature creep-resistant ability, poor heat resistance and so on, the yttrium-rich rare earth high-strength heat-resistant creep-resistant die casting magnesium alloy is developed. The alloy comprises the following constituents: 8.5 to 9.5 percent of Al, 0.4 to 0.9 percent of Zn, 0.2 to 0.6 percent of Mn, 0.1 to 1.5 percent of rare earth Y, 0.01 to 0.15 percent of Er, 0.01 to 0.1 percent of Ho, impurity elements (Fe is less than or equal to 0.02 percent, Cu is less than or equal to 0.002 percent, Si is less than or equal to 0.01, and Ni is less than or equal to 0.001 percent), and the balance being magnesium. A rare earth raw material is a large amount of cheap yttrium-rich rare earth which is remained after high valence elements such as Eu, Dy, Tb and Lu are extracted from mixed rare earth. The prior idle rare earth resource is fully utilized, mechanical properties of room temperature and high temperature of the yttrium-rich rare earth high-strength heat-resistant creep-resistant die casting magnesium alloy are superior to those of AZ91 alloy, the minimum creep rate at a temperature of 150 DEG C under the pressure of 75MPa is 1.53*10s, and the creep elongation of 100 hours is 0.22 percent.