High-strength heat-proof rare earth magnesium alloy and preparation method thereof

The invention discloses a high-strength heat-proof rare earth magnesium alloy and a part formation method. The alloy comprises the following components in percentage by weight: 2.0-6.0% of Zn, 2.0-4.0% of RE, 0.4-0.8% of Zr, 0.6-2.0% of Y and the balance of Mg. The part formation method comprises the following steps: melting magnesium and zinc raw materials into a magnesium-zinc alloy melt, then heating to 720-740DEG C, adding Mg-Re and Mg-Y, and dissolving evenly to obtain a mixed fuse; then heating the mixed fuse to 780-800DEG C, adding Mg-Zr and preserving heat; introducing Ar gas at 700-720DEG C and refining; and preheating an extrusion die, cooling the temperature of the magnesium alloy fuse to a casting temperature, pouring the preheated die and performing direct extrusion formation at 60MPa-2GPa, maintaining pressure and ejecting a casting. The rare earth-magnesium alloy easily generates Mg-Zn-Y quasi-crystal, has excellent room temperature and high temperature mechanical performances, the content of rare earth is low and the cost is saved; the provided preparation method is simple, safe and reliable in technology, and can meet the industrial production requirement.