Preparation method of flame-retardant and corrosion-resistant Mg-Al-Ca-Ce magnesium alloy

Abstract

According to the preparation method of the flame-retardant and corrosion-resistant Mg-Al-Ca-Ce magnesium alloy, the comprehensive performance of an existing magnesium alloy is improved by changing heat treatment process conditions, controlling element adding types and adding amounts and the like, so that the low-cost, flame-retardant and corrosion-resistant Mg-Al-Ca-Ce magnesium alloy is obtained, the concept is ingenious, the design is reasonable, and the preparation method is suitable for industrial production. The preparation method is simple, easy to operate and beneficial to large-scale application of industrial production. The average hydrogen evolution rate of the magnesium alloy soaked in a 3.5 wt.% NaCl solution for 7 days is 5.121-4.713 mm / y, and compared with Mg-Al-Ca with the hydrogen evolution rate of 20.2222 mm / y, the corrosion resistance of the magnesium alloy is improved by 3 times; the tensile strength is 267-318 MPa, the yield strength is 174-253 MPa, the ductility is 11.9%-13.0% and is higher than that of an Mg-Al-Ca alloy, and the tensile strength and the yield strength are improved by about 34 MPa and 39 MPa respectively; and the ignition temperature is 897-1126 DEG C and is higher than the ignition temperature of 897 DEG C of the Mg-Al-Ca alloy.

Description

Technical Field

[0001] This invention belongs to the field of magnesium alloy materials technology, specifically relating to a low-cost, high flame-retardant, high corrosion-resistant, and high-strength Mg-Al-Ca-Ce magnesium alloy and its preparation method. Background Technology

[0002] Magnesium alloys are hailed as "green and environmentally friendly engineering materials of the 21st century." They are currently the lightest metallic materials used in engineering applications, possessing properties such as low density, high specific strength, good vibration damping, excellent damping performance, good electrical conductivity, strong electromagnetic shielding, good machinability, and dimensional stability. Furthermore, they offer advantages such as good casting properties, abundant resources, environmental friendliness, and easy recycling, leading to their widespread use in automotive research and development, military weaponry, hydrogen storage, and other fields. However, existing magnesium alloys suffer from poor corrosion resistance, poor flame retardancy, or a trade-off between strength and plasticity, thus limiting their widespread application.

[0003] In current technologies, the mainstream research directions for magnesium alloy properties mainly include mechanical properties and corrosion or flame retardant properties, such as mechanical properties versus corrosion properties, or mechanical properties versus flame retardant properties. Mechanical properties are typically improved by introducing a second phase into magnesium alloys through alloying. However, when the mechanical properties of magnesium alloys are improved, their corrosion resistance often decreases, which is the current contradiction in the development of magnesium alloys for industrial applications. Surface treatment technology can simultaneously improve the mechanical properties and corrosion resistance of magnesium alloys, but its processes are complex, costly, and unsuitable for the production of large-scale components, thus hindering large-scale application. In recent years, the widespread use of magnesium alloys in aerospace, military manufacturing, and other fields has made high flame retardancy one of the essential characteristics that magnesium alloys should possess. Therefore, researching methods for preparing magnesium alloys with high flame retardancy, high corrosion resistance, and good mechanical properties is an important issue that needs to be addressed by those skilled in the art. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the existing technology, the purpose of this invention is to provide a method for preparing flame-retardant and corrosion-resistant Mg-Al-Ca-Ce magnesium alloy, so as to obtain a low-cost magnesium alloy with better comprehensive performance and solve the problem that flame retardancy, corrosion resistance and mechanical properties cannot be achieved at the same time.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a flame-retardant and corrosion-resistant Mg-Al-Ca-Ce magnesium alloy, characterized by comprising the following steps: (1) Preparation of raw materials: by mass percentage, Al: 4wt.%, Ca: 3wt.%, Ce: 0.2~1wt.%, unavoidable impurities less than or equal to 0.05wt.%, balance Mg; (2) Smelting: After heating and melting the magnesium metal under a protective gas, add the calcium metal and the cerium metal one after another, heat until completely melted, mix evenly, add the aluminum metal, continue heating until completely melted, mix evenly, remove the bottom precipitate and infusible matter, raise the temperature to 750℃, hold for 10 min, remove the surface slag to obtain a pure magnesium alloy melt. (3) Solidification: The magnesium alloy melt described in step (2) is placed in tap water at 15~20℃ to cool it, and a magnesium alloy ingot is obtained; (4) Machining: Machining the magnesium alloy ingot obtained in step (3) to remove the irregular and defective parts at the top and bottom, and take the magnesium alloy ingot with a height of 60mm in the middle for later use. (5) Solution treatment: The magnesium alloy ingot after machining in step (4) is subjected to solution treatment at 500℃; (6) Hot extrusion molding: The ingot after solution treatment in step (5) is preheated at 330℃ for 5 hours, extruded and then water-cooled to obtain extruded bars, resulting in a low-cost, flame-retardant, corrosion-resistant, high-strength and high-toughness Mg-Al-Ca-Ce magnesium alloy.

[0006] Furthermore, the raw materials in step (1) are selected from: the magnesium metal is industrial pure magnesium with a purity greater than or equal to 99.97 wt.%; the calcium metal is Mg-25Ca master alloy; the cerium metal is Mg-30Ce master alloy; and the aluminum metal is pure aluminum granules with a purity greater than or equal to 99.99 wt.%. Industrial pure magnesium is selected to reduce the influence of harmful impurities such as Fe, Ni, and Cu and to ensure the consistency of matrix properties. Master alloys are selected for calcium and cerium metals to solve the problem of differences in melting point and density, reduce oxidation loss, and accurately control the composition ratio. Pure aluminum granules are selected for aluminum metals to avoid impurities affecting alloy properties and to improve smelting efficiency.

[0007] Furthermore, the protective gas in step (2) is a mixture of CO2 and SF6; the volume ratio of CO2 to SF6 in the mixture is 99:1. The reason for choosing a mixture of CO2 and SF6 as the protective gas is that their combined use can compensate for each other's shortcomings. CO2 acts as a carrier, providing basic protection while reducing the amount of SF6 used, thus reducing cost and environmental impact. SF6 acts as a reinforcing agent; a small amount (1%) of SF6 is sufficient to enhance the stability of the CO2 membrane. The reason for choosing a volume ratio of 99:1 is that the effective protective concentration of SF6 is extremely low. When the SF6 content is 1%, a continuous and dense film can be formed on the melt surface to prevent combustion. If the SF6 content is too high, it will increase cost and greenhouse gas emissions without providing additional protection.

[0008] Furthermore, the heating temperature in step (2) is 750°C. Melting at this temperature ensures both fluidity and alloy uniformity, while also controlling the risk of oxidation through a protective gas.

[0009] Furthermore, the solution treatment in step (5) is performed at a temperature of 500°C for 12 hours. By dissolving the Ca and Ce-related reinforcing phases at high temperature and then homogenizing them through long-term diffusion, a matrix with uniform composition and good plasticity is provided for subsequent extrusion.

[0010] Furthermore, the hot extrusion ratio in step (6) is 25:1. Because the extrusion ratio is relatively small, the requirements for the extrusion equipment are lower.

[0011] The preparation process of this invention includes: material preparation – melting – solidification – machining – solution treatment – ​​hot extrusion molding. By changing the heat treatment process conditions and controlling the types and amounts of added elements, the comprehensive properties of existing magnesium alloys are improved, thereby obtaining a low-cost, flame-retardant, and corrosion-resistant Mg-Al-Ca-Ce magnesium alloy. Its concept is ingenious, its design is reasonable, and its preparation method is simple and easy to operate, which is conducive to large-scale industrial application. The innovation of this invention lies in: (1) Low-temperature extrusion-water cooling method. ① The low-temperature extrusion-water cooling method makes the corrosion product film denser and more uniform, hindering Cl - ① Corrosion of the magnesium matrix. ② Regarding flame retardant properties, low-temperature extrusion and water cooling form a dense oxide film on the alloy surface, effectively hindering the contact between oxygen and the magnesium matrix; low-temperature extrusion and water cooling also suppresses the segregation of Ca and Ce elements, resulting in a more uniform distribution, improving film stability, and enhancing flame retardant properties. In contrast, high-temperature extrusion and air cooling cause the oxide film to become loose and thickened, making it prone to cracking. Furthermore, this invention has a smaller extrusion ratio and lower requirements for extrusion equipment.

[0012] (2) Cooling is achieved using tap water at 15~20℃. ① Regarding corrosion resistance, water cooling enables rapid solidification, significantly inhibiting grain growth and forming a fine and uniform α-Mg matrix; during casting, it easily forms a coarse and continuous network β phase (Mg). 17 Al 12 This becomes a corrosion channel, and water cooling causes Al2Ca and Al to... 11 The finer and more dispersed Ce3 phase reduces the potential difference with the matrix, thus minimizing galvanic corrosion. Water cooling promotes the incorporation of oxides such as CeO2 and Al2O3 into the surface film, forming a MgO-CeO2-Al2O3 composite protective layer that effectively blocks the penetration of corrosive media. Water cooling also accelerates the enrichment of impurities such as Fe in the Ce-containing phase, reducing the micro-cell effect between Fe and α-Mg, thereby significantly reducing the corrosion rate. ② Regarding flame retardant properties, water cooling results in a more uniform Ca distribution, rapidly generating a continuous CaO oxide film at high temperatures, isolating oxygen and inhibiting Mg vapor volatilization. Ce forms small-sized oxides during rapid cooling, consuming active oxygen and filling oxide film pores, inhibiting internal oxidation. The fine-grained structure reduces the flow of liquid magnesium at high temperatures, thus delaying the spread of combustion.

[0013] (3) Adding Ca to magnesium alloys can form a uniform and continuously distributed second phase Al2Ca, which hinders the diffusion of corrosion in the alloy, increases the density of the corrosion product film, and thus improves its protective effect on the alloy matrix; the addition of Ce and Al elements enables magnesium alloys to form a corrosion product layer with Ce2O3 and Al(OH)3, which can better fill corrosion pits. Adding Al, Ca, and Ce elements to magnesium alloys forms a high-melting-point second phase (Al2Ca and Al2Ca). 11 The formation of oxides (CeO2, CaO) increases the density of the composite oxide layer. The P / B ratio of Al2O3 > 1 gives the composite layer a certain density. CeO2 and CaO fill the pores of MgO, causing the oxide volume to expand and increasing its density, thereby improving the flame retardant properties of the magnesium alloy. Furthermore, the addition of Al, Ca, and Ce elements to the magnesium alloy can refine the grains and increase the content of the second phase, increasing the hindering effect on dislocations and thus improving strength. Simultaneously, the hot extrusion process effectively reduces casting defects, increases alloy density, and improves its mechanical properties.

[0014] 2. The flame-retardant and corrosion-resistant Mg-Al-Ca-Ce magnesium alloy prepared by the method of the present invention has significantly improved flame-retardant and corrosion-resistant properties, achieving unexpected technical effects! Specifically, the following are the characteristics: (1) The average hydrogen evolution rate after soaking in 3.5wt.% NaCl solution for 7 days is 5.121~4.713mm / y, which is 3 times higher than that of Mg-Al-Ca with a hydrogen evolution rate of 20.222mm / y; (2) The tensile strength is 267~318MPa, the yield strength is 174~253MPa, and the elongation is 11.9~13.0%, which is higher than that of Mg-Al-Ca alloy. The tensile strength and yield strength are increased by about 34MPa and 39MPa, respectively; (3) The ignition temperature is 897~1126℃, which is higher than that of Mg-Al-Ca alloy with an ignition temperature of 897℃.

[0015] 3. Compared with existing VW94 and WE43 alloys, the cost of the magnesium alloy prepared by this invention is only 30-50%. Attached Figure Description

[0016] Figure 1 SEM images of the Mg-Al-Ca-Ce magnesium alloy prepared in Example 2 and the Mg-Al-Ca magnesium alloy prepared in Comparative Example 1.

[0017] Figure 2 The hydrogen evolution test results are obtained by immersing the Mg-Al-Ca-Ce magnesium alloys prepared in Examples 1, 2 and 3 and the Mg-Al-Ca magnesium alloy prepared in Comparative Example 1 in 3.5 wt.% NaCl solution for 7 days.

[0018] Figure 3 The ignition temperatures of the Mg-Al-Ca-Ce magnesium alloys prepared in Examples 1, 2, and 3, and the Mg-Al-Ca magnesium alloy prepared in Comparative Example 1 are measured. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of this invention clearer, specific examples are provided below to illustrate the embodiments of this invention. Those skilled in the art can easily understand other advantages and effects of this invention from the content disclosed in this specification. This invention can also be implemented or applied through other different specific embodiments.

[0020] Example 1 A method for preparing a flame-retardant and corrosion-resistant Mg-Al-Ca-Ce magnesium alloy includes the following steps: (1) First, prepare the corresponding raw materials according to Al: 4wt.%, Ca: 3wt.%, Ce: 0.2wt.%, unavoidable impurities less than or equal to 0.05wt.%, and the balance being the weight percentage of Mg. Among them, magnesium comes from industrial pure magnesium with a purity greater than or equal to 99.97wt.%, aluminum comes from pure aluminum granules with a purity greater than or equal to 99.99wt.%, calcium comes from Mg-25Ca master alloy, and cerium comes from Mg-30Ce master alloy; (2) Smelting: Place the raw material Mg (pure magnesium ingot) into the crucible of the resistance furnace, continuously introduce protective gas, heat to completely melt Mg, add raw materials Ca (Mg-25Ca master alloy) and Ce (Mg-30Ce master alloy) in sequence, heat until completely melted, stir and mix evenly, then add raw material Al (pure aluminum granules), heat until completely melted and stir and mix evenly, remove the bottom precipitate and unmelted matter, then raise the temperature to 750℃ and hold for 10 minutes, remove the surface slag, and obtain pure magnesium alloy melt; (3) Solidification: The magnesium alloy melt described in step (2) is placed in tap water at about 15°C to cool it, and a magnesium alloy ingot is obtained; (4) Machining: Machining the magnesium alloy ingot described in step (3) to remove the irregular and defective parts at the top and bottom, and take the magnesium alloy ingot with a height of 60mm in the middle for later use. (5) Solution treatment: The magnesium alloy ingot after machining in step (4) is subjected to solution treatment at 500°C; (6) Hot extrusion molding: The ingot after solution treatment in step (4) is preheated at 330℃ for 5 hours, extruded and then water-cooled to obtain extruded bars, which are low-cost, high flame retardant, high corrosion resistant and high-strength and tough Mg-Al-Ca-Ce magnesium alloys. Example

[0021] A method for preparing a flame-retardant and corrosion-resistant Mg-Al-Ca-Ce magnesium alloy includes the following steps: (1) First, prepare the corresponding raw materials according to Al: 4wt.%, Ca: 3wt.%, Ce: 0.6wt.%, unavoidable impurities less than or equal to 0.05wt.%, and the balance being the weight percentage of Mg. Among them, magnesium comes from industrial pure magnesium with a purity greater than or equal to 99.97wt.%, aluminum comes from pure aluminum granules with a purity greater than or equal to 99.99wt.%, calcium comes from Mg-25Ca master alloy, and cerium comes from Mg-30Ce master alloy; (2) Smelting: Place the raw material Mg (pure magnesium ingot) into the crucible of the resistance furnace, continuously introduce protective gas, heat to completely melt Mg, add raw materials Ca (Mg-25Ca master alloy) and Ce (Mg-30Ce master alloy) in sequence, heat until completely melted, stir and mix evenly, then add raw material Al (pure aluminum granules), heat until completely melted and stir and mix evenly, remove the bottom precipitate and unmelted matter, then raise the temperature to 750℃ and hold for 10 minutes, remove the surface slag, and obtain pure magnesium alloy melt; (3) Solidification: The magnesium alloy melt described in step (2) is placed in tap water at 15°C to cool it, and a magnesium alloy ingot is obtained; (4) Machining: Machining the magnesium alloy ingot described in step (3) to remove the irregular and defective parts at the top and bottom, and take the magnesium alloy ingot with a height of 60mm in the middle for later use. (5) Solution treatment: The magnesium alloy ingot after machining in step (4) is subjected to solution treatment at 500°C; (6) Hot extrusion molding: The ingot after solution treatment in step (4) is preheated at 330℃ for 5 hours, extruded and then water-cooled to obtain extruded bars, which are Mg-Al-Ca-Ce magnesium alloys with high flame retardancy, high corrosion resistance and high strength and toughness. Example

[0022] A method for preparing a flame-retardant and corrosion-resistant Mg-Al-Ca-Ce magnesium alloy, comprising the following steps: (1) First, prepare the corresponding raw materials according to Al: 4wt.%, Ca: 3wt.%, Ce: 1.0wt.%, unavoidable impurities less than or equal to 0.05wt.%, and the balance being the weight percentage of Mg. Among them, magnesium comes from industrial pure magnesium with a purity greater than or equal to 99.97wt.%, aluminum comes from pure aluminum granules with a purity greater than or equal to 99.99wt.%, calcium comes from Mg-25Ca master alloy, and cerium comes from Mg-30Ce master alloy; (2) Smelting: Place the raw material Mg (pure magnesium ingot) into the crucible of the resistance furnace, continuously introduce protective gas, heat to completely melt Mg, add raw materials Ca (Mg-25Ca master alloy) and Ce (Mg-30Ce master alloy) in sequence, heat until completely melted, stir and mix evenly, then add raw material Al (pure aluminum granules), heat until completely melted and stir and mix evenly, remove the bottom precipitate and unmelted matter, then raise the temperature to 750℃ and hold for 10 minutes, remove the surface slag, and obtain pure magnesium alloy melt; (3) Solidification: The magnesium alloy melt described in step (2) is placed in tap water at 15°C to cool it, and a magnesium alloy ingot is obtained; (4) Machining: Machining the magnesium alloy ingot described in step (3) to remove the irregular and defective parts at the top and bottom, and take the magnesium alloy ingot with a height of 60mm in the middle for later use. (5) Solution treatment: The magnesium alloy ingot after machining in step (4) is subjected to solution treatment at 500°C; (6) Hot extrusion molding: The ingot after solution treatment in step (4) is preheated at 330℃ for 5 hours, extruded and then water-cooled to obtain extruded bars, which are Mg-Al-Ca-Ce magnesium alloys with high flame retardancy, high corrosion resistance and high strength and toughness.

[0023] The method for preparing Mg-Al-Ca rods includes the following steps: (1) First, prepare the corresponding raw materials according to the weight percentage of Al: 4wt.%, Ca: 3wt.%, unavoidable impurities less than or equal to 0.05wt.%, and the balance being Mg. Among them, magnesium comes from industrial pure magnesium with a purity greater than or equal to 99.97wt.%, aluminum comes from pure aluminum granules with a purity greater than or equal to 99.99wt.%, and calcium comes from Mg-25Ca intermediate alloy. (2) Smelting: Place the raw material Mg (pure magnesium ingot) into the crucible of the resistance furnace, continuously introduce protective gas, heat to completely melt Mg, add raw material Ca (Mg-25Ca master alloy) in sequence, heat until completely melted, stir and mix evenly, then add raw material Al (pure aluminum granules), heat until completely melted and stir and mix evenly, remove the bottom precipitate and unmelted matter, then raise the temperature to 750℃ and hold for 10 minutes, remove the surface slag, and obtain pure magnesium alloy melt; (3) Solidification: The magnesium alloy melt described in step (2) is placed in tap water at 15°C to cool it, and a magnesium alloy ingot is obtained; (4) Machining: Machining the magnesium alloy ingot described in step (3) to remove the irregular and defective parts at the top and bottom, and take the magnesium alloy ingot with a height of 60mm in the middle for later use. (5) Solution treatment: The magnesium alloy ingot after machining in step (4) is subjected to solution treatment at 500°C; (6) Hot extrusion molding: The ingot after solution treatment in step (4) is preheated at 330℃ for 5 hours, extruded and then water-cooled to obtain extruded bars, which are Mg-Al-Ca-Ce magnesium alloys with high flame retardancy, high corrosion resistance and high strength and toughness.

[0024] 1. Microscopic tissue analysis: Figure 1SEM images of the Mg-Al-Ca-Ce magnesium alloy prepared in Example 2 and the Mg-Al-Ca magnesium alloy prepared in Comparative Example 1. As can be seen from the images, after the addition of Ce, the Mg-Al-Ca-Ce magnesium alloy prepared in Example 2 exhibits a uniformly distributed granular second phase.

[0025] 2. Hydrogen evolution test The flame-retardant and corrosion-resistant Mg-Al-Ca-Ce magnesium alloys prepared in Examples 1, 2, and 3, and the Mg-Al-Ca magnesium alloy prepared in Comparative Example 1, were respectively subjected to a 3.5 wt.% NaCl solution for 7 days. The hydrogen evolution test results are as follows: Figure 2 As shown. From Figure 2 It can be seen that the hydrogen evolution rate of the flame-retardant and corrosion-resistant Mg-Al-Ca-Ce magnesium alloys prepared in Examples 1-3 of this invention is significantly lower than that of the Mg-Al-Ca magnesium alloy in Comparative Example 1, and the corrosion resistance is improved by about 3 times. The hydrogen evolution rate of the flame-retardant and corrosion-resistant Mg-Al-Ca-Ce magnesium alloy prepared in Example 2 of this invention can be as low as 4.713 mm / y.

[0026] 3. Flame retardant performance test Figure 3 The figures show the test results of the ignition temperatures of the flame-retardant and corrosion-resistant Mg-Al-Ca-Ce magnesium alloys prepared in Examples 1, 2, and 3, and the Mg-Al-Ca magnesium alloy prepared in Comparative Example 1. As can be seen from the figures, the ignition temperatures of the flame-retardant and corrosion-resistant Mg-Al-Ca-Ce magnesium alloys prepared in Examples 1-3 of this invention are significantly higher than those of the Mg-Al-Ca magnesium alloy in Comparative Example 1, with an increase of approximately 229°C. The ignition temperature of the flame-retardant and corrosion-resistant Mg-Al-Ca-Ce magnesium alloy prepared in Example 2 of this invention can reach 1126°C.

[0027] 4. Mechanical property testing Tensile tests were conducted on the flame-retardant and corrosion-resistant Mg-Al-Ca-Ce magnesium alloys prepared in Examples 1, 2, and 3, and the Mg-Al-Ca magnesium alloy prepared in Comparative Example 1. The results are shown in Table 1. As can be seen from Table 1, the yield strength and tensile strength of the flame-retardant and corrosion-resistant Mg-Al-Ca-Ce magnesium alloy prepared in Example 2 of this invention are higher than those of the Mg-Al-Ca magnesium alloy in Comparative Example 1, while the elongation remains relatively unchanged. The yield strength and tensile strength are increased by 39 MPa and 34 MPa, respectively.

[0028] In summary, the flame-retardant and corrosion-resistant Mg-Al-Ca-Ce magnesium alloys prepared in Examples 1 to 3 of this invention have tensile strengths of 267 to 318 MPa, yield strengths of 224 to 294 MPa, and elongations of 11.9 to 13.0%.

[0029] Table 1. Test results of mechanical properties of magnesium alloys In summary, this invention discloses a low-cost, high-flame-retardant, high-corrosion-resistant, and high-strength Mg-Al-Ca-Ce magnesium alloy and its preparation method. The hydrogen evolution rate of this magnesium alloy can reach 5.121~4.713 mm / y, which is three times higher in corrosion resistance compared to the Mg-Al-Ca magnesium alloy with a hydrogen evolution rate of 20.222 mm / y. The tensile strength of the Mg-Al-Ca-Ce magnesium alloy of this invention is 267~318 MPa, the yield strength is 224~294 MPa, and the elongation is 11.9~13.0%. The ignition temperature of the Mg-Al-Ca-Ce magnesium alloy obtained by this invention is 897~1126℃, which is approximately 229℃ higher than the ignition temperature of the Mg-Al-Ca magnesium alloy with an ignition temperature of 897℃. This invention achieves unexpected technical results for aircraft interior decoration, meeting the requirements of mechanical, corrosion-resistant, and flame-retardant properties.

[0030] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments. More other equivalent embodiments may be included without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for preparing a fire-retardant, corrosion-resistant Mg-Al-Ca-Ce magnesium alloy, characterized in that, The method comprises the following steps: (1) preparing raw materials: according to the mass percentage, Al: 4wt.%, Ca: 3wt.%, Ce: 0.2~1wt.%, unavoidable impurities less than or equal to 0.05wt.%, and the balance is Mg; unavoidable impurities less than or equal to 0.05wt.%, and the balance is Mg; (2) smelting: after the metallic magnesium is heated and melted under a protective gas, metallic calcium and metallic cerium are added in sequence, heated to complete melting, and then metallic aluminum is added after being uniformly mixed, and the mixture is continuously heated to complete melting, and then uniformly mixed, and after removing the bottom precipitated non-meltable substance, the temperature is raised to 750℃, and the temperature is maintained for 10min, and the surface dross is removed to obtain a pure magnesium alloy melt; (3) solidification: the magnesium alloy melt in step (2) is cooled in tap water at 15~20℃ to obtain a magnesium alloy ingot; (4) machining: the magnesium alloy ingot obtained in step (3) is machined to remove the upper and lower irregularities and defective parts, and a 60mm high magnesium alloy ingot in the middle is taken for standby; (5) solid solution treatment: the magnesium alloy ingot after machining treatment in step (4) is subjected to solid solution treatment at 500℃; (6) hot extrusion molding: the ingot after solid solution treatment in step (5) is preheated at 330℃ for 5h, and then extruded and water-cooled to obtain an extruded rod, thereby obtaining a low-cost, flame-retardant, corrosion-resistant, high-toughness Mg-Al-Ca-Ce magnesium alloy.

2. The method for preparing the Mg-Al-Ca-Ce magnesium alloy according to claim 1, characterized in that, The raw materials in step (1) are selected from: the metallic magnesium is industrial pure magnesium with a purity greater than or equal to 99.97wt.%; the metallic calcium is Mg-25Ca intermediate alloy; the metallic cerium is Mg-30Ce intermediate alloy; and the metallic aluminum is pure aluminum particles with a purity greater than or equal to 99.99wt.%.

3. The method for preparing the Mg-Al-Ca-Ce magnesium alloy according to claim 1, characterized in that, The protective gas in step (2) is a mixed gas formed by CO2 gas and SF6 gas; and the volume ratio of CO2 to SF6 gas in the mixed gas is 99:

1.

4. The method for preparing the Mg-Al-Ca-Ce magnesium alloy according to claim 1, characterized in that, The heating temperature in step (2) is 750℃.

5. The method for preparing the Mg-Al-Ca-Ce magnesium alloy according to claim 1, characterized in that, The solid solution treatment temperature in step (5) is 500℃, and the time is 12h.

6. The method of claim 3, wherein the Mg-Al-Ca-Ce magnesium alloy is prepared by the steps of: a) preparing a Mg-Al-Ca alloy by melting and casting; b) adding Ce to the Mg-Al-Ca alloy; and c) homogenizing the Mg-Al-Ca-Ce alloy. The hot extrusion ratio in step (6) is 25:1.

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