High-strength magnesium-lithium alloy and preparation method thereof

Abstract

The invention provides high-strength magnesium-lithium alloy and a preparation method thereof. Commercial pure Mg, commercial pure Li, commercial pure Zn, Mg-RY middle alloy are taken as materials; the high-strength magnesium-lithium alloy is prepared from the materials by mass percent: 4.5-5.5% of Li, 2.0-3.8% of RY, 0.2-1.0% of Zn, less than 0.03% of gross of inevitable Fe, Cu, Ni and Si impurities, and the balance of Mg in a mixing manner according to the ratio. The preparation method comprises the steps of: based on commercial pure Mg, commercial pure Li, commercial pure Zn, Mg-RY middle alloy as materials, mixing the following components in percentage by mass: 4.5-5.5% of Li, 2.0-3.8% of RY, 0.2-1.0% of Zn, less than 0.03% of gross of inevitable Fe, Cu, Ni and Si impurities, and the balance of Mg; smelting in a vacuum induction smelting furnace, wherein the inside of the furnace is vacuumized before smelting, and then aerating argon is aerated to protect, the smelting process is carried out under protection of argon atmosphere, and the smelting temperature is 660-750 DEG C; casting the smelted melt into a metal die to obtain as-cast alloy; carrying out hot extrusion for at least twice to obtain the high-strength magnesium-lithium alloy. The obtained alloy disclosed by the invention has high strength and good plasticity; the tensile strength at room temperature is 220-260 MPa; the yield strength is 180-220MPa; the elongation percentage is 15-25%.

Description

technical field [0001] The invention relates to a magnesium-based alloy, and the invention also relates to a preparation method of the magnesium-based alloy. Background technique [0002] Magnesium-lithium alloy is the lightest metal structural material. It has the advantages of low density, high specific strength and specific stiffness, good shock absorption, and easy cutting. It is considered to be the best material for lightweight production of spacecraft and automobiles. [0003] At present, there are mainly three grades of magnesium-lithium alloys that have been industrially used in the world; MA21, MA18 and LA141, but the strength of these three magnesium-lithium alloys is not very high. Therefore, increasing the strength of Mg-Li alloys is an important issue. In the patent document with application number 200410096186.1, a lithium-containing magnesium alloy material and its preparation method are disclosed. Alloying elements such as Al, RE, Zn, and Zr are used to str...

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Problems solved by technology

However, the Li content of these two types of alloys is relatively high. Although the high Li content ensures that the alloy has good plasticity, it will inevitably cause an increase in the cost of the alloy, and it will also affect the strength, thermal stability and corrosion resistance of the alloy.

In addition, the traditional deformation treatment process (such as: extrusion, rolling, etc.) has very limited strengthening effect on the β phase, which leads to the fact that the β phase or α+β dual-phase magnesium-lithium alloy will not be greatly improved in the subsequent deformation treatment. increase strength