High-strength high-modulus double-phase magnesium-lithium alloy and preparation method thereof

Abstract

The invention discloses a high-strength high-modulus double-phase magnesium-lithium alloy and a preparation method thereof, and belongs to the technical field of metal material magnesium alloys. The high-strength and high-modulus double-phase magnesium-lithium alloy is prepared from the following components in percentage by mass: 0.05 to 4 percent of Gd, 0.5 to 5 percent of Al, 0.05 to 8 percent of Y, 5 to 10 percent of Li, 0 to 5 percent of Zn, 0.05 to 4 percent of Mn and the balance of Mg and inevitable impurities. Wherein the content of the Zn element cannot be 0. The preparation method comprises a raw material preparation stage, a raw material preheating stage, a heat treatment furnace atmosphere adjustment stage, a vacuum melting stage, a vacuum tube furnace atmosphere adjustment stage and a heat treatment stage. The microalloying and heat treatment combined mode is adopted, the low density of the double-phase magnesium-lithium alloy can be controlled, and meanwhile the strength, the ductility and the elastic modulus of the double-phase magnesium-lithium alloy are cooperatively improved.

Description

technical field [0001] The invention belongs to the technical field of metal material magnesium alloys, and relates to a high-strength, high-modulus dual-phase magnesium-lithium alloy and a preparation method thereof. Background technique [0002] Magnesium alloys have the characteristics of light weight, high specific strength, and good biocompatibility. With the intensification of the global energy resource crisis and the rapid development of the automobile, aerospace and 3C industries, researchers have to turn their attention to lightweight, environmentally friendly and energy-saving high-performance metal structural parts, and have successively developed various new types of high-performance Magnesium alloys have promoted the further industrial production and application of magnesium alloy materials. [0003] Magnesium-lithium alloy is by far the smallest metal structure material, also known as ultra-light alloy. Due to the low density of the lithium element, the densi...

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Problems solved by technology

[0007] Chinese patent CN107523770B discloses a heat treatment process for improving the performance of a long-range structured ordered phase-strengthened dual-phase magnesium-lithium alloy. The synergistic improvement of strength and elastic modulus by solution treatment and aging treatment is not considered, so the tensile strength of the obtained magnesium-lithium alloy is 120-180MPa lower than 320MPa, the yield strength is 100-150MPa lower than 280MPa, and the elongation is lower than 16 %, the magnesium-lithium alloy obtained by this patent still cannot meet the demand for material performance in practical industrial applications, and needs to be improved

[0008] Chinese patent CN112680641A discloses a Zn-containing dual-phase magnesium-lithium alloy in solid solution state and its preparation method and application. The preparation method is to effectively improve the mechanical strength of the dual-phase magnesium-lithium alloy by adopting Zn element and solid solution heat treatment process. However, The tensile strength of the finally obtained Zn-containing dual-phase magnesium-lithium alloy is 221-302MPa lower than 320MPa and the yield strength 168-275MPa is lower than 280MPa, and the elongation is far less than 16%. Therefore, although it adopts solution heat treatment to improve the strength of the alloy, However, the strength has not yet reached the desired target for practical applications; in addition, it uses a large amount of Zn elements (>8wt.%) to improve the alloy strength, because the density of Zn is relatively high, adding a large amount of Zn elements will cause the increase of the density of the Mg-Li alloy , cannot meet the technical requirements of low density, high specific strength and high specific modulus of magnesium-lithium alloys, thus limiting its engineering application range

[0009] Chinese patent CN113430436A discloses a low-density, high-elastic-modulus as-cast dual-phase magnesium-lithium alloy and its preparation method. The preparation method is to increase the elastic modulus of the dual-phase magnesium-lithium alloy material by in-situ self-generated quasi-crystalline phases, but its The elastic modulus of the obtained magnesium-lithium alloy is still lower than 50GPa, which is far from meeting the needs of practical applications. It is also expected to significantly increase the modulus of magnesium-lithium alloys, thereby promoting the practical engineering application of ultra-light magnesium-lithium alloys

In addition, the α+β duplex structure with the optimal ratio of α phase and β phase can be seen from the examples, the highest tensile strength obtained is 240MPa lower than 320MPa, the highest yield strength is 190MPa lower than 280MPa, and the strength has not yet reached Desired Goals for Practical Applications

[0011] In summary, in order to meet the technical requirements for high strength or high elongation of dual-phase magnesium-lithium alloys in the research of magnesium-lithium alloys, microalloying, heat treatment, and thermal processing have been adopted, but they cannot control the strength of dual-phase magnesium. The low density of lithium alloys synergistically improves the strength and elongation of the dual-phase magnesium-lithium alloy, making the tensile strength, yield strength and elongation highly matched, and the elastic modulus is not less than 60GPa

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