The invention provides a high-
toughness heat-resisting
pressure casting Mg-Gd
alloy and a preparation method thereof. The high-
toughness heat-resisting
pressure casting Mg-Gd
alloy comprises components including, by stoichiometric ratio, 4.0%-8.0% of Gd, 1.2%-4.8% of Zn, 0.5%-1.2% of Al, 0.1%-0.3% of Mn, 0.01%-0.08% of M and the balance Mg, wherein M is one or two elements of Ti and B. The preparation method comprises the steps that firstly, materials are prepared according to Mg-Gb
alloy components; secondly, industrial pure
magnesium ingots are melted; thirdly, the temperature is raised to 720 DEG C, industrial pure
zinc, Mg-Gd and Mg-Mn intermediate alloys are added and stirred to be completely melted; fourthly, the temperature is raised to 730 DEG C, after industrial pure aluminum ingots, Al-Ti, Al-Ti-B and Al-B intermediate alloys are sequentially added,
magnesium alloy melt is obtained after refining; and fifthly, the
magnesium alloy melt is cooled to a
pressure casting temperature so as to be subjected to pressure
casting, and a pressure
casting alloy is obtained. The strength of extension of the alloy in a pressure
casting state at the
room temperature reaches 318 MPa, thestrength of extension of the alloy at the high temperature of 200 DEG C reaches 218 MPa, the
room temperature ductility reaches 12.0%, the high-
toughness heat-resisting pressure casting Mg-Gd alloy can be used without aging or solution heat treatment, and the high-end requirement of
aerospace and other industries for light weight is met.