Magnesium alloy and preparation method thereof

Abstract

The invention discloses a magnesium alloy and a preparation method thereof, and relates to the technical field of magnesium alloys. The magnesium alloy comprises the following components in percentage by mass: 5-7% of dysprosium element, 4-5% of neodymium element, 2-3% of cerium element, 3-5% of zinc element, 0.8-1% of zirconium element and the balance of magnesium element. By controlling the components of the magnesium alloy, the obtained magnesium alloy has good mechanical properties and flame retardance and is suitable for being applied to the fields of aerospace, electronic communication, automobile industry and the like.

Description

Technical Field

[0001] The present application relates to the technical field of magnesium alloys, and in particular to a magnesium alloy and a preparation method thereof. Background Art

[0002] Magnesium alloys have broad application prospects in aerospace, electronic communications, and the automotive industry due to their low density and excellent casting properties. However, the less than ideal strength of magnesium alloys and their flammable properties limit their application. In traditional applications, the flame retardancy of magnesium alloys mainly relies on the protection of gas or liquid solvents, but this method is costly and has a limited scope of application. Alloying is a new method to improve the flame retardancy of magnesium alloys. Currently, the flame retardancy of magnesium alloys is mainly improved by adding rare earth elements, but the improvement effect is limited, and it is difficult for magnesium alloys to have both high strength and high flame retardancy. Summary of the invention

[0003] The main purpose of the present application is to provide a magnesium alloy and a preparation method thereof, so as to solve the problem in the prior art that magnesium alloys are difficult to have both high strength and high flame retardancy.

[0004] In order to achieve the above-mentioned purpose, according to the first aspect of the present application, a magnesium alloy is provided. Taking the mass fraction of the magnesium alloy as 100%, the magnesium alloy includes the following components in mass fraction: 5% to 7% dysprosium (Dy), 4% to 5% neodymium (Nd), 2% to 3% cerium (Ce), 3% to 5% zinc (Zn), 0.8% to 1% zirconium (Zr), and the balance is magnesium.

[0005] Furthermore, the mass ratio of the total mass of the dysprosium element, the neodymium element and the cerium element to the zinc element is (3:1) to (3.5:1).

[0006] Furthermore, the mass ratio of zinc element to zirconium element is (4.3:1) to (5:1), and the mass fraction of zinc element in the magnesium alloy is 4.3% to 5%.

[0007] According to the second aspect of the present application, there is provided a method for preparing the magnesium alloy of the first aspect of the present application, comprising the following steps:

[0008] S1, mixing raw materials according to a ratio to obtain a first mixture;

[0009] S2, melting the first mixture under an environmentally friendly insulating gas to obtain a melt;

[0010] S3, casting the melt and cooling it naturally to obtain a first solid;

[0011] S4, performing a solution treatment on the first solid to obtain a second solid;

[0012] S5, performing aging treatment on the second solid to obtain a third solid;

[0013] S6, rolling the third solid to obtain the magnesium alloy.

[0014] Furthermore, in S2, the environmentally friendly insulating gas is a mixture of SF6 and CO2, or a mixture of SF6 and N2, or a mixture of SF6, CO2 and N2.

[0015] Furthermore, in S2, the smelting temperature is 750°C to 900°C, and the smelting time is 20 min to 25 min.

[0016] Furthermore, in S2, after the smelting is completed, the temperature is kept at room temperature for 15 to 20 minutes to obtain a melt.

[0017] Further, in S3, the melt is injected into a casting machine and cooled naturally to obtain a first solid.

[0018] Furthermore, in S4, the temperature of the solution treatment is 350° C. to 450° C., the time of the solution treatment is 8 h to 10 h, and water quenching or oil quenching is performed after the solution treatment.

[0019] Furthermore, in S5, the temperature of the aging treatment is 300° C. to 400° C., the time of the aging treatment is 4 h to 8 h, and natural cooling is performed after the aging treatment is completed.

[0020] Furthermore, in S6, the temperature of the rolling process is 100° C. to 200° C., and the rolling deformation amount of the rolling process is 20% to 30%.

[0021] Furthermore, in S4, before the solution treatment, the first solid is milled.

[0022] By applying the technical solution of the present application, by adding dysprosium, neodymium and cerium to the magnesium alloy, the three rare earth elements can synergistically improve the flame retardant properties of the magnesium alloy. At high temperatures, they will preferentially combine with oxygen elements to form dense oxides on the surface of the magnesium alloy. In addition, dysprosium can refine the organization and play a role in fine grain strengthening. Neodymium can enhance the precipitation strengthening effect of the alloy. Cerium can promote the precipitation phase to precipitate along the grain boundary, further enhancing the strengthening effect. In addition, the addition of zinc and zirconium can promote the formation of zirconium oxide on the surface of the magnesium alloy during the combustion process, enhancing the flame retardant properties. The addition of zirconium is also beneficial to improving the mechanical properties of the magnesium alloy. At the same time, zinc can also work together with rare earth elements to promote the formation of rare earth oxide film. By controlling the composition and proportion of the magnesium alloy, the various components can synergistically improve the mechanical properties and flame retardant properties of the magnesium alloy, which is beneficial to broadening the application field of the magnesium alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a metallographic microscope image of the magnesium alloy in Example 1. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0025] As described in the background of the present application, there is a problem in the prior art that magnesium alloys are difficult to have both high strength and high flame retardancy. In order to solve the above problem, in a typical embodiment of the present application, a magnesium alloy is provided, which includes the following components by mass fraction: 5% to 7% of dysprosium, 4% to 5% of neodymium, 2% to 3% of cerium, 3% to 5% of zinc, 0.8% to 1% of zirconium, and the balance is magnesium, based on the mass fraction of the magnesium alloy being 100%.

[0026] Dysprosium can react with oxygen to form dense oxides, and the affinity of oxygen to dysprosium is greater than that of magnesium. Therefore, during combustion, dysprosium can react with oxygen first; at the same time, dysprosium can refine the structure and play a role in fine grain strengthening. Neodymium can enhance the precipitation strengthening effect of magnesium alloys and enhance the mechanical properties of the alloys. Cerium can also react with oxygen to form oxides, and at the same time, cerium can promote the precipitation of precipitation phases along grain boundaries to enhance the strengthening effect. Zirconium can react with oxygen to form a dense oxide film, but the migration effect of zirconium to the metal surface during combustion is not good. Only part of the zirconium added to the magnesium alloy can participate in the formation of the oxide film. When zinc is present in the magnesium alloy, a synergistic effect can be produced. During the combustion process, zinc will promote the migration of zirconium to the surface of the magnesium alloy, increase the proportion of zirconium oxide on the surface of the magnesium alloy, and enhance the flame retardant effect. In addition, zirconium can strengthen the matrix and improve the mechanical properties of the alloy during solid solution and precipitation. In addition, zinc can produce precipitation phase with rare earth elements, promote the reaction of rare earth elements with oxygen, promote the formation of rare earth oxide film, and improve the flame retardant properties of magnesium alloy. By controlling the composition and dosage of magnesium alloy, different components can work synergistically to significantly improve the mechanical properties and flame retardant properties of magnesium alloy. In addition, the magnesium alloy has low density, good specific strength and wide application range.

[0027] In the magnesium alloy described in the present application, the mass fraction of dysprosium is 5% to 7%, specifically, it can be 5%, 5.5%, 6%, 6.5%, 7%, etc., or other values ​​within the range, which is not specifically limited here. The mass fraction of neodymium is 4% to 5%, specifically, it can be 4%, 4.5%, 5%, etc., or other values ​​within the range, which is not specifically limited here. The mass fraction of cerium is 2% to 3%, specifically, it can be 2%, 2.5%, 3%, etc., or other values ​​within the range, which is not specifically limited here. The mass fraction of zinc is 3% to 5%, specifically, it can be 3%, 3.5%, 4%, 4.5%, 5%, etc., or other values ​​within the range, which is not specifically limited here. The mass fraction of zirconium is 0.8% to 1%, specifically, it can be 0.8%, 0.9%, 1%, etc., or other values ​​within the range, which is not specifically limited here.

[0028] In some embodiments, the mass ratio of the total mass of dysprosium, neodymium and cerium to zinc is (3:1) to (3.5:1). Specifically, it can be 3:1, 3.2:1, 3.3:1, 3.5:1, etc., or other values ​​within this range, which are not particularly limited herein.

[0029] By controlling the mass ratio of three rare earth elements, namely dysprosium, neodymium and cerium, to zinc, a network-like precipitated phase (MgZnRe) can be formed. This precipitated phase can further exert the effects of zinc and rare earth elements. During combustion, an oxide film is preferentially formed on the surface of the magnesium alloy, which plays a good flame retardant role.

[0030] In some embodiments, the mass ratio of zinc element to zirconium element is (4.3:1) to (5:1), specifically, it can be 4.3:1, 4.5:1, 5:1, etc., or it can be other values ​​within this range, which is not particularly limited here; the mass fraction of zinc element in the magnesium alloy is 4.3% to 5%, specifically, it can be 4.3%, 4.5%, 4.8%, 5%, etc., or it can be other values ​​within this range, which is not particularly limited here.

[0031] By controlling the mass ratio of zinc and zirconium, the flame retardant and mechanical properties of the magnesium alloy can be further improved while maintaining good processing performance of the magnesium alloy.

[0032] In another typical embodiment of the present application, a method for preparing the magnesium alloy in the above embodiment is provided, comprising the following steps:

[0033] S1, mixing raw materials according to a ratio to obtain a first mixture;

[0034] S2, melting the first mixture under an environmentally friendly insulating gas to obtain a melt;

[0035] S3, casting the melt and cooling it naturally to obtain a first solid;

[0036] S4, performing a solution treatment on the first solid to obtain a second solid;

[0037] S5, performing aging treatment on the second solid to obtain a third solid;

[0038] S6, rolling the third solid to obtain the magnesium alloy.

[0039] In S1 of the present application, the accuracy of the alloy composition is ensured by mixing the components according to the ratio, which is the basis for preparing high-performance magnesium alloys. Accurate composition control helps to achieve the best performance of the alloy, including strength, flame retardancy and other mechanical properties. In S2, environmentally friendly insulating gas provides necessary protection for the smelting process, which can prevent the alloy from oxidizing at high temperatures. In S3, casting is a low-cost molding method that can produce parts with complex structures or irregular shapes, suitable for large-scale production. In S4, solution treatment can make the alloy elements fully dissolved in the magnesium matrix to form a uniform solid solution, laying the foundation for subsequent precipitation strengthening and flame retardant performance. In S5, aging treatment can precipitate the supersaturated solid solution in the magnesium alloy to form a fine precipitation phase, which helps to improve the mechanical properties of the magnesium alloy, such as strength and hardness, and also helps to improve the flame retardant properties of the magnesium alloy, so that various alloy elements can give full play to their role. In S6, the tensile strength of the magnesium alloy can be further improved by rolling. By adopting the above steps to prepare the magnesium alloy, the optimal performance of the magnesium alloy can be achieved, so that the magnesium alloy has both high strength and excellent flame retardant properties.

[0040] In some embodiments, in S2, the environmentally friendly insulating gas is a mixture of SF6 and CO2, or a mixture of SF6 and N2, or a mixture of SF6, CO2 and N2.

[0041] SF6, CO2 and N2 can all form an inert atmosphere, effectively preventing the oxidation of magnesium alloys during the smelting process and protecting the purity of magnesium alloys. The use of the above-mentioned mixed gas can, on the one hand, have a good protective effect, help stabilize the smelting process, and improve the safety of the preparation process; on the other hand, it can reduce its negative impact on the environment.

[0042] In some embodiments, in S2, the smelting temperature is 750°C to 900°C, specifically, it can be 750°C, 800°C, 850°C, 900°C, etc., or it can be other values ​​within the range, which is not specifically limited here; the smelting time is 20min to 25min, specifically, it can be 20min, 21min, 22min, 23min, 24min, 25min, etc., or it can be other values ​​within the range, which is not specifically limited here.

[0043] Under the above conditions, each component can be fully melted, which helps to improve the comprehensive properties of the magnesium alloy.

[0044] In some embodiments, in S2, after the smelting is completed, the temperature is kept warm for 15 to 20 minutes to obtain a melt; specifically, the temperature can be kept warm for 15 minutes, 16 minutes, 17 minutes, 18 minutes, 19 minutes, 20 minutes, etc., or other values ​​within the range, which are not particularly limited here.

[0045] Continuing the heat preservation treatment after the smelting is completed helps to further evenly distribute the various elements in the magnesium alloy, and helps to reduce the thermal stress generated by the magnesium alloy during the smelting process, thereby improving the overall performance and processability of the magnesium alloy.

[0046] In some embodiments, in S3, the melt is injected into a casting machine and cooled naturally to obtain a first solid.

[0047] In the present application, natural cooling includes air cooling and pile cooling. Natural cooling during the casting process helps to reduce internal stress, reduce deformation and cracks of the casting during the cooling process, and improve the strength of the magnesium alloy; in addition, natural cooling also helps to promote the uniform distribution of elements in the alloy and improve the comprehensive performance of the magnesium alloy.

[0048] In some embodiments, in S4, the temperature of the solution treatment is 350°C to 450°C, specifically, it can be 350°C, 400°C, 450°C, etc., or other values ​​within this range, and is not specifically limited here; the time of the solution treatment is 8h to 10h, and water quenching or oil quenching is performed after the solution treatment is completed.

[0049] Solution treatment can make the alloy elements fully dissolve into the magnesium matrix to form a uniform solid solution. In addition, rapid cooling methods such as water quenching or oil quenching can fix the microstructure obtained during the solution treatment and avoid redistribution of elements during the cooling process, thereby obtaining higher hardness and strength.

[0050] In some embodiments, in S5, the temperature of the aging treatment is 300°C to 400°C, specifically, it can be 300°C, 320°C, 340°C, 380°C, etc., or it can be other values ​​within the range, which is not specifically limited here; the time of the aging treatment is 4h to 8h, specifically, it can be 4h, 5h, 6h, 7h, 8h, etc., or it can be other values ​​within the range, which is not specifically limited here; the aging treatment is completed by natural cooling.

[0051] Through aging treatment, the supersaturated solid solution in the alloy begins to decompose and precipitate the second phase, such as MgZnRe phase. These precipitated phases are usually small, evenly distributed particles, which can significantly improve the hardness and strength of magnesium alloys. In addition, the precipitated phase also has a good flame retardant effect. During combustion, the precipitated phase can effectively absorb oxygen, reduce the combustion rate of magnesium alloys, and improve their flame retardant properties. In addition, aging treatment can also promote the internal balance of the material, keep the alloy in a stable state, and maintain the optimal state of the microstructure of the magnesium alloy.

[0052] In some embodiments, in S6, the temperature of the rolling treatment is 100℃~200℃, specifically, it can be 100℃, 120℃, 140℃, 180℃, etc., or it can be other values ​​within this range, which is not specifically limited here; the rolling deformation of the rolling treatment is 20%~30%, specifically, it can be 20%, 22%, 24%, 28%, 30%, etc., or it can be other values ​​within this range, which is not specifically limited here.

[0053] In this application, rolling deformation refers to the reduction in thickness, which is the ratio of the thickness reduction value to the original thickness. By controlling the temperature of the rolling process within the above range, on the one hand, the rolling efficiency can be improved, the grains in the alloy can be refined through plastic deformation, and the strength of the magnesium alloy can be improved; on the other hand, the generation of cracks and defects can be reduced, and the mechanical properties and flame retardancy of the magnesium alloy can be improved.

[0054] In some embodiments, in S4, before solution treatment, the first solid is milled; further, the thickness of the milled surface is 1 mm to 2 mm, specifically, it can be 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, etc., or other values ​​within the range, which are not specifically limited here.

[0055] Milling can remove the oxide scale, carbide deposition, casting defects, surface damage caused by heat treatment, etc. generated during the preparation of magnesium alloys, which helps to reduce stress concentration and improve the mechanical properties of magnesium alloys. In addition, milling can significantly improve the surface finish of the alloy, help reduce friction and wear, and improve the accuracy and reliability of magnesium alloys, making it suitable for use in aerospace or precision instrument manufacturing.

[0056] The present application is further described in detail below in conjunction with specific embodiments. These embodiments should not be construed as limiting the scope of protection claimed in the present application.

[0057] Example 1

[0058] An embodiment of the magnesium alloy of the present application, the composition of the magnesium alloy of the present embodiment is shown in Table 1, and the preparation method comprises the following steps:

[0059] S1, mixing raw materials according to a ratio to obtain a first mixture;

[0060] S2, melting the first mixture in a mixed gas of SF6 and CO2 (the volume ratio of SF6 and CO2 is 1:99) at a melting temperature of 850°C for 20 minutes, and keeping the temperature for 18 minutes after the melting is completed to obtain a melt;

[0061] S3, injecting the melt into a casting machine, air cooling, and obtaining a first solid;

[0062] S4, milling the first solid to a thickness of 2 mm, then performing a solid solution treatment at a solid solution temperature of 420° C. for a solid solution time of 8.5 h, and water cooling to obtain a second solid;

[0063] S5, performing aging treatment on the second solid at an aging temperature of 380° C. for 6 h, and air cooling to obtain a third solid;

[0064] S6, rolling the third solid at a rolling temperature of 150° C. and a rolling deformation of 20% to obtain the magnesium alloy.

[0065] Example 2

[0066] An embodiment of the magnesium alloy of the present application, the composition of the magnesium alloy of the present embodiment is shown in Table 1, and the preparation method comprises the following steps:

[0067] S1, mixing raw materials according to a ratio to obtain a first mixture;

[0068] S2, melting the first mixture in a mixed gas of SF6 and CO2 (the volume ratio of SF6 and CO2 is 1:99) at a melting temperature of 900° C. for 20 min, and keeping the mixture warm for 20 min after the melting is completed to obtain a melt;

[0069] S3, injecting the melt into a casting machine, air cooling, and obtaining a first solid;

[0070] S4, milling the first solid to a thickness of 2 mm, then performing a solid solution treatment at a solid solution temperature of 450° C. for a solid solution time of 8 h, and water cooling to obtain a second solid;

[0071] S5, performing aging treatment on the second solid at an aging temperature of 300° C. for an aging time of 8 h, and air cooling to obtain a third solid;

[0072] S6, rolling the third solid at a rolling temperature of 200° C. and a rolling deformation of 30% to obtain the magnesium alloy.

[0073] Example 3

[0074] An embodiment of the magnesium alloy of the present application, the composition of the magnesium alloy of the present embodiment is shown in Table 1, and the preparation method comprises the following steps:

[0075] S1, mixing raw materials according to a ratio to obtain a first mixture;

[0076] S2, melting the first mixture in a mixed gas of SF6 and CO2 (the volume ratio of SF6 and CO2 is 1:99) at a melting temperature of 780°C for 25 minutes, and keeping the temperature for 15 minutes after the melting is completed to obtain a melt;

[0077] S3, injecting the melt into a casting machine, air cooling, and obtaining a first solid;

[0078] S4, milling the first solid to a thickness of 2 mm, then performing a solid solution treatment at a solid solution temperature of 350° C. for a solid solution time of 10 h, and water cooling to obtain a second solid;

[0079] S5, performing aging treatment on the second solid at an aging temperature of 400° C. for an aging time of 8 h, and air cooling to obtain a third solid;

[0080] S6, rolling the third solid at a rolling temperature of 100° C. and a rolling deformation of 25% to obtain the magnesium alloy.

[0081] Example 4

[0082] An embodiment of the magnesium alloy of the present application, the composition of the magnesium alloy of the present embodiment is shown in Table 1, and the preparation method comprises the following steps:

[0083] S1, mixing raw materials according to a ratio to obtain a first mixture;

[0084] S2, melting the first mixture in a mixed gas of SF6 and CO2 (the volume ratio of SF6 and CO2 is 1:99) at a melting temperature of 800° C. for 25 min, and keeping the mixture warm for 15 min after the melting is completed to obtain a melt;

[0085] S3, injecting the melt into a casting machine, air cooling, and obtaining a first solid;

[0086] S4, milling the first solid to a thickness of 2 mm, then performing a solid solution treatment at a solid solution temperature of 420° C. for a solid solution time of 8.5 h, and water cooling to obtain a second solid;

[0087] S5, performing aging treatment on the second solid at an aging temperature of 400° C. for 6 h, and air cooling to obtain a third solid;

[0088] S6, rolling the third solid at a rolling temperature of 100° C. and a rolling deformation of 20% to obtain the magnesium alloy.

[0089] Example 5

[0090] An embodiment of the magnesium alloy of the present application, the composition of the magnesium alloy of the present embodiment is shown in Table 1, and the preparation method comprises the following steps:

[0091] S1, mixing raw materials according to a ratio to obtain a first mixture;

[0092] S2, melting the first mixture in a mixed gas of SF6 and CO2 (the volume ratio of SF6 and CO2 is 1:99) at a melting temperature of 850°C for 20 minutes, and keeping the temperature for 18 minutes after the melting is completed to obtain a melt;

[0093] S3, injecting the melt into a casting machine, air cooling, and obtaining a first solid;

[0094] S4, milling the first solid to a thickness of 1 mm, then performing a solid solution treatment at a solid solution temperature of 420° C. for a solid solution time of 8 h, and water cooling to obtain a second solid;

[0095] S5, performing aging treatment on the second solid at an aging temperature of 350° C. for 8 h, and air cooling to obtain a third solid;

[0096] S6, rolling the third solid at a rolling temperature of 150° C. and a rolling deformation of 20% to obtain the magnesium alloy.

[0097] Comparative Example 1

[0098] A magnesium alloy, the composition of which is shown in Table 1, and a preparation method thereof comprises the following steps:

[0099] S1, mixing raw materials according to a ratio to obtain a first mixture;

[0100] S2, melting the first mixture in a mixed gas of SF6 and CO2 (the volume ratio of SF6 and CO2 is 1:99) at a melting temperature of 800° C. for 25 min, and keeping the mixture warm for 15 min after the melting is completed to obtain a melt;

[0101] S3, injecting the melt into a casting machine, air cooling, and obtaining a first solid;

[0102] S4, milling the first solid to a thickness of 2 mm, then performing a solid solution treatment at a solid solution temperature of 420° C. for a solid solution time of 8.5 h, and water cooling to obtain a second solid;

[0103] S5, performing aging treatment on the second solid at an aging temperature of 420° C. for 6 h, and air cooling to obtain a third solid;

[0104] S6, rolling the third solid at a rolling temperature of 100° C. and a rolling deformation of 20% to obtain the magnesium alloy.

[0105] Comparative Example 2

[0106] A magnesium alloy, the composition of which is shown in Table 1, and a preparation method thereof comprises the following steps:

[0107] S1, mixing raw materials according to a ratio to obtain a first mixture;

[0108] S2, melting the first mixture in a mixed gas of SF6 and CO2 (the volume ratio of SF6 and CO2 is 1:99) at a melting temperature of 800° C. for 25 min, and keeping the mixture warm for 15 min after the melting is completed to obtain a melt;

[0109] S3, injecting the melt into a casting machine, air cooling, and obtaining a first solid;

[0110] S4, milling the first solid to a thickness of 2 mm, then performing a solid solution treatment at a solid solution temperature of 420° C. for a solid solution time of 8.5 h, and water cooling to obtain a second solid;

[0111] S5, performing aging treatment on the second solid at an aging temperature of 420° C. for 6 h, and air cooling to obtain a third solid;

[0112] S6, rolling the third solid at a rolling temperature of 100° C. and a rolling deformation of 20% to obtain the magnesium alloy.

[0113] Table 1

[0114]

[0115]

[0116] Performance Testing

[0117] The magnesium alloys in the embodiments and comparative examples were subjected to performance tests. The test methods are as follows. The test results are shown in Table 2.

[0118] (1) Room temperature tensile strength: The alloy was processed into thin plate specimens and their strength was tested using a universal tensile machine.

[0119] (2) Ignition point: Take 1 cm each of the head, middle and tail of the magnesium alloy. 3 The block is heated in a closed heat treatment furnace with a heating rate of 5°C / min. A thermocouple is used to measure the temperature change curve of the magnesium alloy surface. The thermocouple probe is placed directly above the sample. When the curve has an inflection point, the ignition point of the block is measured. The minimum temperature measured at three positions of the alloy block is the ignition point of the alloy.

[0120] (3) Density: 1cm 3 For magnesium alloys, density is measured using the water displacement method.

[0121] Table 2

[0122] project Room temperature tensile strength (MPa) Flash point(℃) <![CDATA[Density (g / cm 3 )]]> Example 1 318 712 2.00 Example 2 326 718 2.03 Example 3 336 730 2.08 Example 4 304 702 1.97 Example 5 315 723 2.04 Comparative Example 1 285 685 1.97 Comparative Example 2 259 621 1.97

[0123] From the above test results, it can be seen that the magnesium alloy in the embodiment of the present application has both high strength and excellent flame retardant properties, and its density is relatively low, and the lightweight characteristics of the magnesium alloy are still retained. The composition of the magnesium alloy in Comparative Examples 1 to 2 is somewhat different from that of the magnesium alloy in the present application, and it cannot have both high strength and high flame retardant properties.

[0124] In addition, by comparing the performance test results of Examples 1 to 5, it can be found that when the mass ratio of the total mass of dysprosium, neodymium and cerium elements to the mass ratio of zinc element in the magnesium alloy is (3:1) to (3.5:1), the room temperature tensile strength can reach above 315 MPa, and the ignition point can reach above 710°C, and its comprehensive performance can be further improved; in addition, when the mass ratio of zinc element to zirconium element is (4.3:1) to (5:1), and the mass fraction of zinc element in the magnesium alloy is 4.3% to 5%, its mechanical properties and flame retardant properties can be further improved, which helps to broaden the application field of magnesium alloy.

[0125] Figure 1 This is a metallographic microscope image of the magnesium alloy in Example 1. It can be seen from the figure that precipitated phases are dispersed in the magnesium alloy. On the one hand, these precipitated phases help to improve the mechanical properties of the magnesium alloy. On the other hand, during combustion, they can react preferentially with oxygen to form a stable oxide film, thereby slowing down the combustion rate of the magnesium alloy.

[0126] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A magnesium alloy, characterized in that: Taking the mass fraction of the magnesium alloy as 100%, the magnesium alloy includes the following components in mass fractions: 5% to 7% dysprosium, 4% to 5% neodymium, 2% to 3% cerium, 3% to 5% zinc, 0.8% to 1% zirconium, and the balance is magnesium.

2. The magnesium alloy according to claim 1, characterized in that The mass ratio of the total mass of the dysprosium element, the neodymium element and the cerium element to the zinc element is (3:1) to (3.5:1).

3. The magnesium alloy according to claim 1 or 2, characterized in that: The mass ratio of the zinc element to the zirconium element is (4.3:1) to (5:1); and the mass fraction of the zinc element in the magnesium alloy is 4.3% to 5%.

4. A method for preparing a magnesium alloy according to any one of claims 1 to 3, characterized in that: The steps include: S1, mixing raw materials according to a ratio to obtain a first mixture; S2, melting the first mixture under an environmentally friendly insulating gas to obtain a melt; S3, casting the melt and cooling it naturally to obtain a first solid; S4, performing a solution treatment on the first solid to obtain a second solid; S5, performing aging treatment on the second solid to obtain a third solid; S6, rolling the third solid to obtain the magnesium alloy.

5. The preparation method according to claim 4, characterized in that: The S2 includes at least one of the following features: (1) The environmentally friendly insulating gas is a mixture of SF6 and CO2, or a mixture of SF6 and N2, or a mixture of SF6, CO2 and N2; (2) The smelting temperature is 750° C. to 900° C., and the smelting time is 20 min to 25 min; (3) After the smelting is completed, the heat preservation is continued for 15 minutes to 20 minutes to obtain the melt.

6. The preparation method according to claim 4 or 5, characterized in that: In S3, the melt is injected into a casting machine and cooled naturally to obtain the first solid.

7. The preparation method according to claim 4 or 5, characterized in that: In S4, the temperature of the solution treatment is 350° C. to 450° C., the time of the solution treatment is 8 h to 10 h, and water quenching or oil quenching is performed after the solution treatment.

8. The preparation method according to claim 4 or 5, characterized in that: In S5, the temperature of the aging treatment is 300° C. to 400° C., the time of the aging treatment is 4 h to 8 h, and the aging treatment is followed by natural cooling.

9. The preparation method according to claim 4 or 5, characterized in that: In the step S6, the temperature of the rolling process is 100° C. to 200° C., and the rolling deformation amount of the rolling process is 20% to 30%.

10. The preparation method according to claim 4 or 5, characterized in that: In S4, before the solution treatment, the first solid is milled.

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