Method for regulating and controlling long-range ordered stacking phase of magnesium alloy

Abstract

The invention discloses a method for regulating and controlling a magnesium alloy long-range ordered stacking phase, and belongs to the technical field of metal materials. The process comprises the following steps: preparing raw materials according to alloy components and contents, smelting, and carrying out solution treatment. The LPSO phase regulation and control technology provided by the invention can be used for preparing Mg-Gd-Zn-L series alloys. According to the method, the LPSO phase in the Mg-Gd-Zn-Li alloy can be effectively regulated and controlled by controlling the content of the L element and carrying out composite solution treatment, the solution treatment temperature required for regulating and controlling the LPSO phase can be remarkably reduced by adding the L element, and the solution treatment time is shortened. Compared with the prior art, the LPSO phase regulation and control method is higher in efficiency and more remarkable in practical value.

Description

Technical Field

[0001] The invention relates to a method for regulating LPSO phase in a magnesium alloy by controlling the content of Li element, and belongs to the technical field of metal materials. Background Art

[0002] Magnesium is one of the most abundant metal elements on earth. The density of pure magnesium is the lowest among metal materials. It has a series of advantages such as high specific strength and specific stiffness, good heat dissipation, strong impact resistance and creep resistance, strong damping and noise reduction capabilities, and excellent electromagnetic shielding performance. Driven by the strategy of energy conservation and emission reduction, magnesium alloys can partially replace aluminum alloys and other materials to achieve lightweight and solve certain energy and environmental problems. However, the low absolute strength and absolute stiffness, poor corrosion resistance, high sensitivity to stress concentration, and low yield point of magnesium alloys have limited the large-scale industrial application of magnesium. Therefore, the huge gap between its research value and application has prompted the further development of magnesium alloys.

[0003] According to the forming method, magnesium alloys can be divided into deformed magnesium alloys and cast magnesium alloys. Cast magnesium alloys are manufactured by casting, which is prone to some defects, such as pores and looseness, but the overall process cost is low; while deformed magnesium alloys undergo plastic deformation processing, and the organization is refined after extrusion, rolling, forging and other processes, and the casting defects are eliminated, with higher strength, better ductility and more diverse mechanical properties. Therefore, the organization and structure of deformed magnesium alloys can be regulated by heat treatment, plastic deformation, etc. to improve their mechanical properties.

[0004] At present, research has found that adding rare earth elements to magnesium alloys can significantly improve alloy properties. The functions and effects of rare earth elements include: purifying the melt, protecting the melt, fine grain strengthening, solid solution strengthening, aging strengthening, etc. The Mg-RE alloys studied have successively experienced Mg-Th, Mg-Y, and Mg-Gd systems, and a variety of new magnesium alloys with RE as the main element have been developed. At this stage, the most attention is paid to Mg-Gd-Zn, a typical LPSO-type magnesium alloy containing LPSO phase.

[0005] In recent years, the formation of LPSO phase to promote the strengthening and toughening of magnesium alloys has gradually attracted more and more attention, and Mg-RE-TM alloys have gradually become typical magnesium alloys containing LPSO phase. Studies have shown that changing the composition and solution treatment parameters can regulate the formation of long-range ordered stacking phase (LPSO phase) in Mg-Gd-Zn magnesium alloys. LPSO phase can significantly improve the strength, plasticity and other mechanical properties of the alloy, but it is affected by factors such as its type, morphology, volume fraction and distribution. Therefore, the formation of LPSO phase can be reasonably controlled by alloying and improving alloy preparation conditions, thereby obtaining a more excellent strengthening and toughening effect.

[0006] Li is very important in achieving ultra-lightness and superplasticity of magnesium alloys. Mg-Li alloy is the lightest alloy material discovered so far, with advantages such as high specific modulus, high specific strength, and excellent low-temperature plasticity. The addition of Li can not only improve the plasticity of Mg and reduce the density of the alloy, but also promote the aging precipitation of the alloy, produce further strengthening effects, and also regulate the type, quantity, and distribution of LPSO phases. However, for Mg-Gd-Zn alloys, the effect of adding Li on the solution time and solution temperature required to regulate the LPSO phase has not yet been clarified.

[0007] Therefore, it is of great significance to clarify the influence of Li element on the solution heat treatment conditions of LPSO phase and master the process method of further regulating LPSO phase by Li element, which is of great significance for the research and development of new lightweight and high-performance LPSO magnesium alloys. Summary of the invention

[0008] In view of this, the present invention provides a method for regulating the LPSO phase in magnesium alloys by controlling the content of Li element, as the control conditions of the LPSO phase of existing magnesium alloys have not yet been clarified, and the content of a specific element (Li) in the alloy is crucial to the formation of the LPSO phase. The present invention can effectively regulate the LPSO phase in the Mg-Gd-Zn-Li alloy by controlling the content of Li element through composite solid solution treatment. The addition of Li element can significantly reduce the solid solution treatment temperature required for regulating the LPSO phase and shorten the solid solution treatment time, providing a solution to solve the problem of regulating the LPSO phase in magnesium alloys.

[0009] The technical solution of the present invention is:

[0010] A method for regulating the LPSO phase in a magnesium alloy by controlling the Li element content comprises the following steps:

[0011] 1) A magnesium alloy having an LPSO phase, wherein the composition is calculated by mass percentage as follows: Gd: 7-9%, Zn: 1%, Li: 0-3% and not 3%, and the remainder is Mg and unavoidable impurities;

[0012] 2) preparing raw materials according to alloy composition and content: preparing raw materials according to alloy composition and ingredients, wherein the raw materials are industrial pure magnesium ingots, pure zinc particles, magnesium-gadolinium master alloy and magnesium-lithium master alloy;

[0013] 3) Melting: Melting the alloy ingredients with good proportion under argon protection, and then pouring at a pouring temperature of 700° C. The casting is air-cooled after being left to stand, to obtain the magnesium alloy ingot;

[0014] 4) Solution treatment: The prepared magnesium alloy ingot is coated with MgO powder and then subjected to solution treatment at a solution temperature of 475°C to 525°C (excluding 525°C) for 8 to 24 hours, and then quenched in cold water and cooled to room temperature.

[0015] A method for regulating the LPSO phase in a magnesium alloy by controlling the Li element content comprises the following steps:

[0016] 1) A magnesium alloy having an LPSO phase, wherein the composition is calculated by mass percentage as follows: Gd: 7-9%, Zn: 1%, Li: 0-0.1%, and the remainder is Mg and unavoidable impurities;

[0017] 2) preparing raw materials according to alloy composition and content: preparing raw materials according to alloy composition and ingredients, wherein the raw materials are industrial pure magnesium ingots, pure zinc particles, magnesium-gadolinium master alloy and magnesium-lithium master alloy;

[0018] 3) Melting: Melting the alloy ingredients with good proportion under argon protection, and then pouring at a pouring temperature of 700° C. The casting is air-cooled after being left to stand, to obtain the magnesium alloy ingot;

[0019] 4) Solution treatment: The prepared magnesium alloy ingot is coated with MgO powder and then subjected to solution treatment at a solution temperature of 525° C. for 8 h, then quenched in cold water and cooled to room temperature.

[0020] In step 2), the master alloys selected when preparing the raw materials include: Mg-30wt% Gd master alloy and Mg-10wt% Li master alloy.

[0021] In step 3), the smelting and casting is:

[0022] S1. Smelting is carried out under argon protection. Industrial pure magnesium ingots and pure zinc particles are placed in a stainless steel crucible in a resistance furnace, and the resistance furnace temperature is set to 740°C for heating. When the pure magnesium and zinc are completely melted, the resistance furnace is powered off.

[0023] S2, add the magnesium-gadolinium master alloy preheated at 200°C, stir for 2 minutes after it melts, and remove the slag after mixing as completely and evenly as possible; then re-energize the resistance furnace and set the temperature to 700°C;

[0024] S3. When the temperature is stable, turn off the power of the resistance furnace, add the magnesium-lithium master alloy preheated to 200°C, wait for it to melt, stir for 1-2 minutes and then remove the slag;

[0025] S4, setting the temperature of the resistance furnace to 700° C., re-energizing it for 20 minutes before pouring, letting the casting stand and then air-cooling it to obtain the magnesium alloy ingot.

[0026] The essential features of the present invention are:

[0027] An alloy containing LPSO phase is obtained by adding and controlling the content of Li element in magnesium rare earth alloy and performing composite solid solution treatment. The present invention adds Gd element and Zn element to magnesium alloy. Gd, as a rare earth element, has a high solubility in magnesium alloy, plays an aging strengthening effect, and can also improve the mechanical properties of the material, reduce pores, and refine grains; Li element can refine dendrites and promote the transformation of LPSO phase. When the Li content is low (<3%), increasing the amount of Li element added can significantly reduce the solution treatment temperature required for regulating the LPSO phase and shorten the solution treatment time; when the Li addition reaches 3%, no LPSO phase is formed. The present invention provides a method for regulating the LPSO phase by controlling the Li element content for magnesium rare earth alloy, which can significantly improve the heat treatment efficiency of regulating the LPSO phase and reduce costs.

[0028] The beneficial effects of the present invention are:

[0029] 1. By controlling the alloy composition, that is, the Li element content, the LPSO phase can be introduced into the alloy matrix. Especially when the Li content is less than 3%, the LPSO phase can be produced, which provides ideas for the preparation of lightweight, high-strength and tough LPSO-type magnesium alloys.

[0030] 2. By controlling the content of Li element, it was found that as the Li content increased, the solution treatment temperature required to generate LPSO phase decreased, the solution treatment time was reduced, and the cost was saved.

[0031] 3.3. The argon gas used in the present invention is an inert protective gas commonly used in laboratories. It is cheap, easy to store and transport, has stable chemical properties, is non-toxic and pollution-free, and has low cost.

[0032] 4.4. The equipment used in the present invention is simple and convenient, with a short experimental cycle, simple operation and safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 A is the OM image of the GZ81 alloy with LPSO phase prepared in Example 1 after solution treatment at 495°C for 8 hours; B is the OM image of the GZ81 alloy without LPSO phase prepared in Example 2 after solution treatment at 525°C for 10 hours. C is a statistical diagram of the solution conditions of the GZ81 alloy with LPSO phase.

[0034] Figure 2 A is the OM image of the GZL8101 alloy with LPSO phase prepared in Example 3 after solution treatment at 475°C for 24h; B is the OM image of the GZL8101 alloy without LPSO phase prepared in Example 4 after solution treatment at 525°C for 24h. C is a statistical diagram of the solution conditions of the GZL8101 alloy with LPSO phase.

[0035] Figure 3 A is the OM image of the GZL8105 alloy with LPSO phase prepared in Example 5 after solution treatment at 485°C for 12 hours; B is the OM image of the GZL8105 alloy without LPSO phase prepared in Example 6 after solution treatment at 525°C for 18 hours. C is a statistical diagram of the solution conditions of the GZL8105 alloy with LPSO phase.

[0036] Figure 4 A is the OM image of the GZL811 alloy with LPSO phase prepared in Example 7 after solution treatment at 475°C for 12 hours; B is the OM image of the GZL811 alloy without LPSO phase prepared in Example 8 after solution treatment at 525°C for 18 hours. C is a statistical diagram of the solution conditions of the GZL811 alloy with LPSO phase.

[0037] Figure 5 A is the OM image of the GZL813 alloy prepared in Example 9 without LPSO phase and dissolved at 475°C for 18 hours. B is a statistical diagram of the solution conditions of the GZL813 alloy with LPSO phase.

[0038] Figure 6 This is a statistical diagram of the presence of LPSO phase in the GZ81, GZL8101, GZL8105, GZL811, and GZL813 alloys prepared in Examples 1-9 of the present invention.

[0039] Figure 7 A is the OM picture of the GZL81 alloy with LPSO phase prepared in Example 10 and dissolved at 525°C for 8 h; B is the OM picture of the GZL8101 alloy with LPSO phase prepared in Example 11 and dissolved at 525°C for 8 h. DETAILED DESCRIPTION

[0040] The technical solution of this invention is further described below with a specific implementation method. The following implementations are all implemented on the premise of the technical solution of the invention, and detailed implementation methods and specific operation processes are given, but the protection scope of the invention is not limited to the following embodiments.

[0041] Example 1

[0042] A magnesium alloy GZ81 having an LPSO phase, and a preparation method thereof is as follows:

[0043] The raw materials are weighed according to the ratio (Mg-8Gd-1Zn), and smelted and cast to obtain magnesium alloy ingots. Among them, the raw materials are industrial pure magnesium ingots, pure zinc particles, magnesium-gadolinium intermediate alloys and magnesium-lithium intermediate alloys; Ar protection is used for smelting. When smelting, the weighed pure magnesium and pure zinc are first put into the crucible, and the resistance furnace temperature is set to 740℃ for heating. When the pure magnesium and pure zinc are completely melted and the temperature of the resistance furnace remains unchanged, the resistance furnace is turned off, and the pre-heated magnesium-gadolinium intermediate alloy is added. After melting, stir for 2 minutes, and remove the slag after mixing as completely and evenly as possible; after all the work is completed, the resistance furnace is powered on again, the temperature is set to 700℃, and the heating and heat preservation are carried out for 20 minutes. After standing, the magnesium alloy ingot is obtained by air cooling.

[0044] Heat treatment was performed to dissolve the alloy at 495°C for 8 hours. After the solution treatment was completed, the sample was taken out and water quenched.

[0045] Example 2

[0046] A magnesium alloy GZ81 without LPSO phase, the preparation method of which is as follows:

[0047] The raw materials are weighed according to the ratio (Mg-8Gd-1Zn), and smelted and cast to obtain magnesium alloy ingots. Among them, the raw materials are industrial pure magnesium ingots, pure zinc particles, magnesium-gadolinium intermediate alloys and magnesium-lithium intermediate alloys; Ar protection is used for smelting. When smelting, the weighed pure magnesium and pure zinc are first put into the crucible, and the resistance furnace temperature is set to 740℃ for heating. When the pure magnesium and pure zinc are completely melted and the temperature of the resistance furnace remains unchanged, the resistance furnace is turned off, and the pre-heated magnesium-gadolinium intermediate alloy is added. After melting, stir for 2 minutes, and remove the slag after mixing as completely and evenly as possible; after all the work is completed, the resistance furnace is powered on again, the temperature is set to 700℃, and the heating and heat preservation are carried out for 20 minutes. After standing, the magnesium alloy ingot is obtained by air cooling.

[0048] Heat treatment was performed to solid-solutionize the alloy at a temperature of 525°C for 10 hours. After the solid-solution was completed, the sample was taken out and water quenched.

[0049] Example 3

[0050] A magnesium alloy GZL8101 having an LPSO phase, and a preparation method thereof is as follows:

[0051] The raw materials are weighed according to the ratio (Mg-8Gd-1Zn-0.1Li), and smelted and cast to obtain magnesium alloy ingots. Among them, the raw materials are industrial pure magnesium ingots, pure zinc particles, magnesium-gadolinium intermediate alloys and magnesium-lithium intermediate alloys; Ar protection is used for smelting. When smelting, the weighed pure magnesium and pure zinc are first put into the crucible, and the resistance furnace temperature is set to 740℃ for heating. When pure magnesium and pure zinc are completely melted and the temperature of the resistance furnace remains unchanged, the resistance furnace is powered off, and the preheated magnesium-gadolinium master alloy is added. After melting, it is stirred and stirred for 2 minutes under the protection of inert gas Ar. After mixing as completely and evenly as possible, slag removal is performed; after all the work is completed, the resistance furnace is powered on again, and the temperature is set to 700°C. When the temperature drops to 700°C and stabilizes, the resistance furnace is powered off, and the magnesium-lithium master alloy preheated at 200°C is added. After melting, it is stirred for 1-2 minutes under the protection of Ar and then slag removal is performed; after all the work is completed, the temperature of the resistance furnace is set to 700°C, and the power is turned on again for 20 minutes before pouring. The casting is air-cooled after standing to obtain the magnesium alloy ingot.

[0052] Heat treatment was performed to solid-solutionize the alloy at a temperature of 475°C for 24 hours. After the solid-solution was completed, the sample was taken out and water quenched.

[0053] Example 4

[0054] A magnesium alloy GZL8101 without LPSO phase, the preparation method of which is as follows:

[0055] The raw materials are weighed according to the ratio (Mg-8Gd-1Zn-0.1Li), and smelted and cast to obtain magnesium alloy ingots. Among them, the raw materials are industrial pure magnesium ingots, pure zinc particles, magnesium-gadolinium intermediate alloys and magnesium-lithium intermediate alloys; Ar protection is used for smelting. When smelting, the weighed pure magnesium and pure zinc are first put into the crucible, and the resistance furnace temperature is set to 740℃ for heating. When pure magnesium and pure zinc are completely melted and the temperature of the resistance furnace remains unchanged, the resistance furnace is powered off, and the preheated magnesium-gadolinium master alloy is added. After melting, it is stirred and stirred for 2 minutes under the protection of inert gas Ar. After mixing as completely and evenly as possible, slag removal is performed; after all the work is completed, the resistance furnace is powered on again, and the temperature is set to 700°C. When the temperature drops to 700°C and stabilizes, the resistance furnace is powered off, and the magnesium-lithium master alloy preheated at 200°C is added. After melting, it is stirred for 1-2 minutes under the protection of Ar and then slag removal is performed; after all the work is completed, the temperature of the resistance furnace is set to 700°C, and the power is turned on again for 20 minutes before pouring. The casting is air-cooled after standing to obtain the magnesium alloy ingot.

[0056] Heat treatment was performed to solid-solutionize the alloy at a temperature of 525°C for 24 hours. After the solid-solution was completed, the sample was taken out and water quenched.

[0057] Example 5

[0058] A magnesium alloy GZL8105 having an LPSO phase, and a preparation method thereof is as follows:

[0059] The raw materials are weighed according to the ratio (Mg-8Gd-1Zn-0.5Li), and smelted and cast to obtain magnesium alloy ingots. Among them, the raw materials are industrial pure magnesium ingots, pure zinc particles, magnesium-gadolinium intermediate alloys and magnesium-lithium intermediate alloys; Ar protection is used for smelting. When smelting, the weighed pure magnesium and pure zinc are first put into the crucible, and the resistance furnace temperature is set to 740℃ for heating. When pure magnesium and pure zinc are completely melted and the temperature of the resistance furnace remains unchanged, the resistance furnace is powered off, and the preheated magnesium-gadolinium master alloy is added. After melting, it is stirred and stirred for 2 minutes under the protection of inert gas Ar. After mixing as completely and evenly as possible, slag removal is performed; after all the work is completed, the resistance furnace is powered on again, and the temperature is set to 700°C. When the temperature drops to 700°C and stabilizes, the resistance furnace is powered off, and the magnesium-lithium master alloy preheated at 200°C is added. After melting, it is stirred for 1-2 minutes under the protection of Ar and then slag removal is performed; after all the work is completed, the temperature of the resistance furnace is set to 700°C, and the power is turned on again for 20 minutes before pouring. The casting is air-cooled after standing to obtain the magnesium alloy ingot.

[0060] Heat treatment was performed to dissolve the alloy at 485°C for 12 hours. After the solution treatment was completed, the sample was taken out and water quenched.

[0061] Example 6

[0062] A magnesium alloy GZL8105 without LPSO phase, and its preparation method is as follows:

[0063] The raw materials are weighed according to the ratio (Mg-8Gd-1Zn-0.5Li), and smelted and cast to obtain magnesium alloy ingots. Among them, the raw materials are industrial pure magnesium ingots, pure zinc particles, magnesium-gadolinium intermediate alloys and magnesium-lithium intermediate alloys; Ar protection is used for smelting. When smelting, the weighed pure magnesium and pure zinc are first put into the crucible, and the resistance furnace temperature is set to 740℃ for heating. When pure magnesium and pure zinc are completely melted and the temperature of the resistance furnace remains unchanged, the resistance furnace is powered off, and the preheated magnesium-gadolinium master alloy is added. After melting, it is stirred and stirred for 2 minutes under the protection of inert gas Ar. After mixing as completely and evenly as possible, slag removal is performed; after all the work is completed, the resistance furnace is powered on again, and the temperature is set to 700°C. When the temperature drops to 700°C and stabilizes, the resistance furnace is powered off, and the magnesium-lithium master alloy preheated at 200°C is added. After melting, it is stirred for 1-2 minutes under the protection of Ar and then slag removal is performed; after all the work is completed, the temperature of the resistance furnace is set to 700°C, and the power is turned on again for 20 minutes before pouring. The casting is air-cooled after standing to obtain the magnesium alloy ingot.

[0064] Heat treatment was performed to solid-solutionize the alloy at a temperature of 525°C for 18 hours. After the solid-solution was completed, the sample was taken out and water quenched.

[0065] Example 7

[0066] A magnesium alloy GZL811 having an LPSO phase, and a preparation method thereof is as follows:

[0067] The raw materials are weighed according to the ratio (Mg-8Gd-1Zn-1Li), and smelted and cast to obtain magnesium alloy ingots. Among them, the raw materials are industrial pure magnesium ingots, pure zinc particles, magnesium-gadolinium intermediate alloys and magnesium-lithium intermediate alloys; Ar protection is used for smelting. When smelting, the weighed pure magnesium and pure zinc are first put into the crucible, and the resistance furnace temperature is set to 740℃ for heating. When pure magnesium and pure zinc are completely melted and the temperature of the resistance furnace remains unchanged, the resistance furnace is powered off, and the preheated magnesium-gadolinium master alloy is added. After melting, it is stirred and stirred for 2 minutes under the protection of inert gas Ar. After mixing as completely and evenly as possible, slag removal is performed; after all the work is completed, the resistance furnace is powered on again, and the temperature is set to 700°C. When the temperature drops to 700°C and stabilizes, the resistance furnace is powered off, and the magnesium-lithium master alloy preheated at 200°C is added. After melting, it is stirred for 1-2 minutes under the protection of Ar and then slag removal is performed; after all the work is completed, the temperature of the resistance furnace is set to 700°C, and the power is turned on again for 20 minutes before pouring. The casting is air-cooled after standing to obtain the magnesium alloy ingot.

[0068] Heat treatment was performed to solid-solutionize the alloy at a temperature of 475°C for 12 hours. After the solid-solution was completed, the sample was taken out and water quenched.

[0069] Example 8

[0070] A magnesium alloy GZL811 without LPSO phase, the preparation method of which is as follows:

[0071] The raw materials are weighed according to the ratio (Mg-8Gd-1Zn-1Li), and smelted and cast to obtain magnesium alloy ingots. Among them, the raw materials are industrial pure magnesium ingots, pure zinc particles, magnesium-gadolinium intermediate alloys and magnesium-lithium intermediate alloys; Ar protection is used for smelting. When smelting, the weighed pure magnesium and pure zinc are first put into the crucible, and the resistance furnace temperature is set to 740℃ for heating. When pure magnesium and pure zinc are completely melted and the temperature of the resistance furnace remains unchanged, the resistance furnace is powered off, and the preheated magnesium-gadolinium master alloy is added. After melting, it is stirred and stirred for 2 minutes under the protection of inert gas Ar. After mixing as completely and evenly as possible, slag removal is performed; after all the work is completed, the resistance furnace is powered on again, and the temperature is set to 700°C. When the temperature drops to 700°C and stabilizes, the resistance furnace is powered off, and the magnesium-lithium master alloy preheated at 200°C is added. After melting, it is stirred for 1-2 minutes under the protection of Ar and then slag removal is performed; after all the work is completed, the temperature of the resistance furnace is set to 700°C, and the power is turned on again for 20 minutes before pouring. The casting is air-cooled after standing to obtain the magnesium alloy ingot.

[0072] Heat treatment was performed to solid-solutionize the alloy at a temperature of 525°C for 18 hours. After the solid-solution was completed, the sample was taken out and water quenched.

[0073] Example 9

[0074] A high-strength magnesium alloy GZL813 without LPSO phase, the preparation method of which is as follows:

[0075] The raw materials are weighed according to the ratio (Mg-8Gd-1Zn-3Li), and smelted and cast to obtain magnesium alloy ingots. Among them, the raw materials are industrial pure magnesium ingots, pure zinc particles, magnesium-gadolinium intermediate alloys and magnesium-lithium intermediate alloys; Ar protection is used for smelting. When smelting, the weighed pure magnesium and pure zinc are first put into the crucible, and the resistance furnace temperature is set to 740℃ for heating. When pure magnesium and pure zinc are completely melted and the temperature of the resistance furnace remains unchanged, the resistance furnace is powered off, and the preheated magnesium-gadolinium master alloy is added. After melting, it is stirred and stirred for 2 minutes under the protection of inert gas Ar. After mixing as completely and evenly as possible, slag removal is performed; after all the work is completed, the resistance furnace is powered on again, and the temperature is set to 700°C. When the temperature drops to 700°C and stabilizes, the resistance furnace is powered off, and the magnesium-lithium master alloy preheated at 200°C is added. After melting, it is stirred for 1-2 minutes under the protection of Ar and then slag removal is performed; after all the work is completed, the temperature of the resistance furnace is set to 700°C, and the power is turned on again for 20 minutes before pouring. The casting is air-cooled after standing to obtain the magnesium alloy ingot.

[0076] Heat treatment was performed to dissolve the alloy at 475°C for 18 hours. After the solution treatment was completed, the sample was taken out and water quenched.

[0077] Example 10

[0078] A magnesium alloy GZ81 having an LPSO phase, and a preparation method thereof is as follows:

[0079] The raw materials are weighed according to the ratio (Mg-8Gd-1Zn), and smelted and cast to obtain magnesium alloy ingots. Among them, the raw materials are industrial pure magnesium ingots, pure zinc particles, magnesium-gadolinium intermediate alloys and magnesium-lithium intermediate alloys; Ar protection is used for smelting. When smelting, the weighed pure magnesium and pure zinc are first put into the crucible, and the resistance furnace temperature is set to 740℃ for heating. When the pure magnesium and pure zinc are completely melted and the temperature of the resistance furnace remains unchanged, the resistance furnace is turned off, and the pre-heated magnesium-gadolinium intermediate alloy is added. After melting, stir for 2 minutes, and remove the slag after mixing as completely and evenly as possible; after all the work is completed, the resistance furnace is powered on again, the temperature is set to 700℃, and the heating and heat preservation are carried out for 20 minutes. After standing, the magnesium alloy ingot is obtained by air cooling.

[0080] Heat treatment was performed to solid-solutionize the alloy at a temperature of 525°C for 8 hours. After the solid-solution was completed, the sample was taken out and water quenched.

[0081] Embodiment 11

[0082] A magnesium alloy GZL8101 having an LPSO phase, and a preparation method thereof is as follows:

[0083] The raw materials are weighed according to the ratio (Mg-8Gd-1Zn-0.1Li), and smelted and cast to obtain magnesium alloy ingots. Among them, the raw materials are industrial pure magnesium ingots, pure zinc particles, magnesium-gadolinium intermediate alloys and magnesium-lithium intermediate alloys; Ar protection is used for smelting. When smelting, the weighed pure magnesium and pure zinc are first put into the crucible, and the resistance furnace temperature is set to 740℃ for heating. When pure magnesium and pure zinc are completely melted and the temperature of the resistance furnace remains unchanged, the resistance furnace is powered off, and the preheated magnesium-gadolinium master alloy is added. After melting, it is stirred and stirred for 2 minutes under the protection of inert gas Ar. After mixing as completely and evenly as possible, slag removal is performed; after all the work is completed, the resistance furnace is powered on again, and the temperature is set to 700°C. When the temperature drops to 700°C and stabilizes, the resistance furnace is powered off, and the magnesium-lithium master alloy preheated at 200°C is added. After melting, it is stirred for 1-2 minutes under the protection of Ar and then slag removal is performed; after all the work is completed, the temperature of the resistance furnace is set to 700°C, and the power is turned on again for 20 minutes before pouring. The casting is air-cooled after standing to obtain the magnesium alloy ingot.

[0084] Heat treatment was performed to solid-solutionize the alloy at a temperature of 525°C for 8 hours. After the solid-solution was completed, the sample was taken out and water quenched.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A method for regulating the LPSO phase in a magnesium alloy by controlling the Li element content, characterized in that: The following steps are involved: 1) A magnesium alloy having an LPSO phase, wherein the composition is calculated by mass percentage as follows: Gd: 7-9%, Zn: 1%, Li: 0-3% and not 3%, and the remainder is Mg and unavoidable impurities; 2) preparing raw materials according to alloy composition and content: preparing raw materials according to alloy composition and ingredients, wherein the raw materials are industrial pure magnesium ingots, pure zinc particles, magnesium-gadolinium master alloy and magnesium-lithium master alloy; 3) Melting: Melting the alloy ingredients with good proportion under argon protection, and then pouring at a pouring temperature of 700° C. The casting is air-cooled after being left to stand, to obtain the magnesium alloy ingot; 4) Solution treatment: The prepared magnesium alloy ingot is coated with MgO powder and then subjected to solution treatment at a solution temperature of 475°C to 525°C (excluding 525°C) for 8 to 24 hours, and then quenched in cold water and cooled to room temperature.

2. A method for regulating the LPSO phase in a magnesium alloy by controlling the Li element content, characterized in that: The following steps are involved: 1) A magnesium alloy having an LPSO phase, wherein the composition is calculated by mass percentage as follows: Gd: 7-9%, Zn: 1%, Li: 0-0.1%, and the remainder is Mg and unavoidable impurities; 2) preparing raw materials according to alloy composition and content: preparing raw materials according to alloy composition and ingredients, wherein the raw materials are industrial pure magnesium ingots, pure zinc particles, magnesium-gadolinium master alloy and magnesium-lithium master alloy; 3) Melting: Melting the alloy ingredients with good proportion under argon protection, and then pouring at a pouring temperature of 700° C. The casting is air-cooled after being left to stand, to obtain the magnesium alloy ingot; 4) Solution treatment: The prepared magnesium alloy ingot is coated with MgO powder and then subjected to solution treatment at a solution temperature of 525° C. for 8 h, then quenched in cold water and cooled to room temperature.

3. The method according to claim 1 or 2, characterized in that Step 1) can introduce Li element into the alloy to regulate the LPSO phase, reduce the solution treatment temperature required for regulating the LPSO phase, and shorten the solution treatment time.

4. The method according to claim 1 or 2, characterized in that: In step 2), the master alloys selected when preparing the raw materials include: Mg-30wt% Gd master alloy and Mg-10wt% Li master alloy.

5. A method for preparing a magnesium alloy having an LPSO phase by adjusting the content of Li element according to claim 1, characterized in that: In step 3), the smelting and casting is: S1. Smelting is carried out under argon protection. Industrial pure magnesium ingots and pure zinc particles are placed in a stainless steel crucible in a resistance furnace, and the resistance furnace temperature is set to 740°C for heating. When the pure magnesium and zinc are completely melted, the resistance furnace is powered off. S2, add the magnesium-gadolinium master alloy preheated at 200°C, stir for 2 minutes after it melts, and remove the slag after mixing as completely and evenly as possible; then re-energize the resistance furnace and set the temperature to 700°C; S3. When the temperature is stable, turn off the power of the resistance furnace, add the magnesium-lithium master alloy preheated to 200°C, wait for it to melt, stir for 1-2 minutes and then remove the slag; S4, setting the temperature of the resistance furnace to 700° C., re-energizing it for 20 minutes before pouring, letting the casting stand and then air-cooling it to obtain the magnesium alloy ingot.

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