Die-casting heat resisting magnesium alloy and preparation thereof

Abstract

The invention relates to a die-casting heat resistant magnesium alloy and a preparation method thereof, pertaining to the metal material technology field. The components and weight percentage thereof of the alloy are as follows: 1.5 to 6.0 percent of Sm, 0 to 3.0 percent of Nd, 0 to 2.5 percent of Ca, 0.1 to 2.0 percent of Zn, 0.2 to 0.8 percent of Zr, lower than 0.02 percent of impurity elements, and the rest is Mg. The preparation method of the alloy comprises the following steps: the materials are weighed, and industrial pure Mg is heated under the protection of the mixed gas of N2 and SF6; after Mg is wholly melted, industrial pure Zn, industrial pure Ca and Mg-Sm interalloy and Mg-Nd interalloy are added at the temperature of 650 to 680 DEG C, Mg-Zr interalloy is added at the temperature of 760 DEG C, the temperature is maintained and the mixture is stirred, then the temperature is increased to 780 to 800 DEG C and maintained, after that the temperature is adjusted to 750 to 760 DEG C for refining and maintained for 30min, and when the Mg liquid is cooled to 680 to 700 DEG C, the mixture carries out die casting. The alloy of the invention has excellent tensile strength, yield strength and elongation and creep resistance simultaneously, and has good die-casting performance.

Description

technical field [0001] The invention relates to an alloy in the technical field of metal materials and a preparation method thereof, in particular to a die-casting heat-resistant magnesium alloy added with alloy elements (Sm, Nd, Ca, Zn, Zr) and a preparation method thereof. Background technique [0002] Lightweight has gradually become the development direction of modern automobiles, and magnesium alloys, as the most promising light alloys, will be more widely used in the automobile industry. At present, the magnesium alloy parts in automobiles are basically die-casting parts. Among the existing cast magnesium alloys, AZ91D, AM50 and other alloys are most widely used. These magnesium alloys have excellent mechanical properties, corrosion resistance and die-casting properties. However, when the operating temperature exceeds 120°C, the creep properties of these alloys drop sharply, so they cannot be used to produce structural parts such as automotive power transmission and l...

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Problems solved by technology

[0003] After searching the prior art, it is found that rare earth elements are considered to be important elements used to improve the heat resistance of magnesium alloys. I.P.Moreno and others in "Scripta Materialia", 2003, 48: 1029-1034, "Microstructural stability and creep of rare -earth containing magnesium alloys" studied the high-temperature stability of Mg-RE-Zn alloy microstructure and the high-temperature creep resistance of the alloy, and found that the addition of rare earth elements and Zn can significantly improve the high-temperature creep resistance of the alloy , but the creep resistance of the alloy decreases significantly in the temperature range above 200 °C

And the Mg-Nd-Zn-Zr alloy (patent number: WO2006105594A1) developed by the CAST Research Center in Australia is also mainly aimed at applications under working conditions below 200°C. In addition, the alloy has low elongation and poor plasticity