High-corrosion-resistance magnesium alloy as well as preparation method and application thereof

Abstract

The invention discloses a high-corrosion-resistance magnesium alloy and a preparation method and application thereof, and belongs to the technical field of magnesium alloys, the high-corrosion-resistance magnesium alloy is based on multi-element rare earth microalloying and dispersed Mg17Al12 phase synergistic regulation, in the high-corrosion-resistance magnesium alloy, a fine dispersed Mg17Al12 second phase is evenly distributed in a whole magnesium matrix, and the high-corrosion-resistance magnesium alloy has the advantages that the high-corrosion-resistance magnesium alloy is obtained; the magnesium alloy has the beneficial effects that the magnesium alloy is good in corrosion resistance, uniform corrosion of a magnesium matrix is promoted, and the micro-galvanic corrosion effect between the Mg17Al12 phase and the magnesium matrix is greatly weakened, so that serious local corrosion of the magnesium alloy in a traditional AZ91 alloy is converted into a uniform corrosion behavior, and the corrosion resistance of the magnesium alloy is greatly improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of magnesium alloys, and particularly relates to a high-corrosion-resistance magnesium alloy and a preparation method and application thereof. BACKGROUND

[0002] As the lightest structural metal material, magnesium alloy has a broad application prospect in the fields of aerospace, automobile, 3C electronic products, etc. due to its low density, high specific strength, excellent damping performance, good electromagnetic shielding performance, and biocompatibility. With the rapid development of national aerospace industry and domestic new energy vehicles, lightweight has become the current development trend. As the lightest structural metal material, magnesium alloy has great potential in the field of lightweight. However, due to the active chemical properties and low standard electrode potential (-2.37 V / SHE) of magnesium, magnesium alloy has a high corrosion tendency in thermodynamics, and is prone to galvanic corrosion when in contact with other metals. In addition, in terms of kinetics, the oxidation film on the surface of magnesium and its alloy is mainly composed of MgO, and the PBR (Pilling-Bedworth ratio) is less than 1, which cannot completely cover the metal surface, resulting in that the oxidation film of magnesium and its alloy is not dense. In addition, the corrosion product Mg(OH)2 generated during the corrosion of magnesium has a loose and porous flaky structure, and does not have good corrosion protection performance, and is easily damaged by corrosive media such as chloride ions. Therefore, magnesium and its alloy exhibit poor corrosion resistance in actual service, which is the main bottleneck limiting the application of magnesium alloy, and the non-dense corrosion product film is the main reason for poor corrosion resistance. SUMMARY

[0003] To solve the problem of poor corrosion resistance of magnesium alloy and promote the application of magnesium alloy in the fields of aerospace, automobile and 3C electronic products, the application provides a high-corrosion-resistance magnesium alloy and a preparation method and application thereof. The high-corrosion-resistance magnesium alloy is a high-corrosion-resistance magnesium alloy based on multi-rare earth micro-alloying and dispersion Mg 17 Al 12 synergistic regulation.

[0004] To achieve the above object, the application provides the following technical scheme.

[0005] The application provides a high-corrosion-resistance magnesium alloy, which is a high-corrosion-resistance magnesium alloy based on multi-rare earth micro-alloying and dispersion Mg 17 Al 12 synergistic regulation. The chemical composition of the high-corrosion-resistance magnesium alloy is as follows in terms of mass percentage: Al: 7-9%, RE: 0.15-0.3%, Mn: 0.05-0.33%, and the balance is Mg and inevitable impurity elements; wherein RE is at least two of Gd, Nd and Er.

[0006] In the high corrosion-resistant magnesium alloy of the present application, the fine and dispersed Mg 17 Al 12 The second phase is uniformly distributed in the magnesium matrix, which is beneficial to promote the uniform corrosion of the magnesium matrix, and greatly weaken the micro-electrode corrosion effect between the phase and the magnesium matrix, so that the magnesium alloy of the present application is converted from the serious local corrosion of the traditional AZ91 alloy to the uniform corrosion behavior, greatly improving the corrosion resistance of the magnesium alloy. 17 Al 12 The second phase is uniformly distributed in the magnesium matrix, which is beneficial to promote the uniform corrosion of the magnesium matrix, and greatly weaken the micro-electrode corrosion effect between the phase and the magnesium matrix, so that the magnesium alloy of the present application is converted from the serious local corrosion of the traditional AZ91 alloy to the uniform corrosion behavior, greatly improving the corrosion resistance of the magnesium alloy.

[0007] The present application also provides a preparation method of the high corrosion-resistant magnesium alloy, comprising the following steps:

[0008] According to the chemical composition of the high corrosion-resistant magnesium alloy, pure magnesium ingot, pure aluminum ingot, Mg-RE intermediate alloy and Mg-Mn intermediate alloy are weighed, and preheating treatment is carried out to remove moisture;

[0009] Under the protection of protective gas, the pure magnesium ingot, the pure aluminum ingot, the Mg-RE intermediate alloy and the Mg-Mn intermediate alloy are mixed, heated and melted to obtain a magnesium alloy melt;

[0010] Under the protection of protective gas, the magnesium alloy melt is refined, stirred, placed and heat preserved, and slagging treatment is carried out to obtain a purified magnesium alloy melt;

[0011] Under the protection of protective gas, the purified magnesium alloy melt is cast into a preheated mold to obtain a magnesium alloy ingot;

[0012] The magnesium alloy ingot is subjected to homogenization treatment, and then extruded into a plate;

[0013] The plate is directly subjected to aging treatment or is subjected to solid solution treatment and then aging treatment to obtain the high corrosion-resistant magnesium alloy.

[0014] Further, the Mg-RE intermediate alloy includes Mg-Gd intermediate alloy, Mg-Nd intermediate alloy and Mg-Er intermediate alloy.

[0015] Further, the protective gas is a mixed gas of SF6 and CO2, and the volume ratio of the two is 1:9.

[0016] Further, the step of obtaining the magnesium alloy melt is as follows:

[0017] Under the protection of SF6 and CO2 mixed gas (volume ratio of 1:9), the pure magnesium ingot is melted at 690℃, then the Mg-Mn intermediate alloy is added in the range of 700-710℃, and stirred for 3-5 minutes;

[0018] adding the pure aluminum ingot in the protection of SF6 and CO2 mixed gas (volume ratio 1:9) in the range of 710-720℃, and then holding for 10-20 minutes until the pure aluminum ingot is melted to obtain a melt;

[0019] adding the Mg-RE intermediate alloy in the protection of SF6 and CO2 mixed gas (volume ratio 1:9) in the range of 750-780℃, and holding for 10-20 minutes to obtain the magnesium alloy melt.

[0020] Further, the temperature of the refining is 740-750℃, and the time of the stirring is 5-10 minutes.

[0021] Further, the step of holding is first holding at 740-750℃ for 30-40 minutes, and then holding at 710-720℃ for 40-50 minutes after cooling.

[0022] Further, when directly performing the aging treatment, the temperature of the aging treatment is 200-300℃, and the time of the aging treatment is 24-72 hours.

[0023] Further, when first performing the solid solution treatment and then performing the aging treatment, the temperature of the solid solution treatment is 400-420℃, the time of the solid solution treatment is 5-8 hours, the temperature of the aging treatment is 200-300℃, and the time of the aging treatment is 24-72 hours.

[0024] The application further provides application of the high corrosion-resistant magnesium alloy in the field of lightening and in the equipment in the field of corrosion resistance.

[0025] For example, the high corrosion-resistant magnesium alloy can be used to prepare aerospace equipment, automobiles and 3C electronic products.

[0026] Compared with the prior art, the application has the following advantages and technical effects:

[0027] (1) The present application is based on the low-cost and most widely used Mg-Al alloy, and a small amount of rare earth elements Gd, Nd and Er is added. The PBR of the oxides Gd2O3, Nd2O3 and Er2O3 formed by the added Gd, Nd and Er elements is 1.29, 1.61 and 1.20 respectively, all greater than 1. When the PBR value of the oxide is between 1 and 2, the oxide film has the advantages of continuity and good protection, which can effectively fill the loose porous defects in the MgO oxide film of Mg, thereby increasing the density of the surface oxide film of the magnesium matrix. In addition, the added rare earth elements can enter the corrosion product film in the form of oxides and hydroxides during the corrosion process to increase the density of the corrosion film layer, thereby improving the corrosion resistance of the magnesium alloy. In addition, unlike a single rare earth element, the addition of two or three trace rare earth elements can produce a synergistic effect, which weakens the segregation problem of a single rare earth element, forms a composite rare earth oxide film, and improves the corrosion resistance of the magnesium alloy. In addition, various types of heterogeneous nucleation cores can be formed, the second phase and grain size are refined, and the mechanical properties are improved.

[0028] (2) First, the rare earth elements Gd, Nd and Er added in the present application can react with impurities such as Fe elements in the melt during the melting process, and reduce the hydrogen content in the melt, thereby achieving the purpose of purifying the melt. Compared with a single rare earth element, the addition of multiple rare earth elements can form a composite rare earth compound, reduce the size of inclusions and uniformly disperse the inclusions, and the effect of removing impurities is better. Currently, the impurities in the conventional commercial AZ31 alloy or AZ91 alloy cannot be well removed during the melting process, which greatly affects the corrosion resistance. Second, the small amount of rare earth (RE) elements added in the present application can react with Al to form Al-RE second phase, and the Al-RE phase formed during solidification can act as a heterogeneous nucleation site to refine the grains, thereby improving the mechanical properties of the magnesium alloy. In addition, the small amount of rare earth elements added in the present application can convert the high-potential Al-Mn phase in the traditional AZ91 alloy into a low-potential Al-Mn-RE phase, thereby weakening the micro-galvanic corrosion of the magnesium matrix; and the rare earth elements added in the present application can refine the coarse network Mg 17 Al 12 phase in the traditional AZ91 alloy, thereby improving the mechanical and corrosion resistance of the magnesium alloy.

[0029] (3) The magnesium alloy with fine and dispersed Mg 17 Al 12 phase can be prepared by subsequent extrusion and heat treatment regulation of the present application. Compared with the coarse network Mg 17 Al 12 phase in the traditional AZ91 alloy, the fine and dispersed Mg 17 Al 12The phase is favorable to promote uniform corrosion of the magnesium matrix, and greatly weakens the micro-electrode corrosion effect between the phase and the magnesium matrix 17 Al 12 The micro-electrode corrosion effect between the phase and the magnesium matrix, so that the magnesium alloy of the application is converted from the serious local corrosion of the traditional AZ91 alloy to a uniform corrosion behavior, greatly improving the corrosion resistance of the magnesium alloy; and the corrosion product film formed under the uniform corrosion behavior is more dense than the corrosion product film formed by the local corrosion of the traditional AZ91 alloy, and has better protection performance. Compared with the traditional AZ91 alloy, the corrosion rate of the magnesium alloy of the application is reduced from 2.3mm / y to 0.12mm / y, and the corrosion resistance is improved by 20 times.

[0030] (4) The high-corrosion-resistant magnesium alloy of the application is a low-cost Mg-Al alloy, only a small amount of rare earth elements are added, and has the advantages of low cost and large-scale production.

[0031] (5) The high-corrosion-resistant magnesium alloy of the application has great application potential in the fields of aerospace, new energy vehicles, 3C electronic products, etc. BRIEF DESCRIPTION OF DRAWINGS

[0032] The accompanying drawings, which form a part of the present application, are used to provide a further understanding of the present application, and the illustrative embodiments thereof and their descriptions are used to explain the present application, and do not constitute improper limitations on the present application. In the drawings:

[0033] Figure 1 It is the SEM microstructure diagram of the high-corrosion-resistant Mg-8Al-0.1Gd-0.1Nd-0.1Er-0.2Mn alloy in Example 1.

[0034] Figure 2 It is the SEM microstructure diagram of the Mg-8Al-0.2Mn alloy in Comparative Example 1.

[0035] Figure 3 It is the SEM microstructure diagram of the extruded Mg-8Al-0.1Gd-0.1Nd-0.1Er-0.2Mn alloy in Comparative Example 7.

[0036] Figure 4 It is the corrosion cross-section morphology of the high-corrosion-resistant Mg-8Al-0.1Gd-0.1Nd-0.1Er-0.2Mn alloy in Example 1 after being immersed in 3.5wt% NaCl solution for 14 days.

[0037] Figure 5 It is the corrosion cross-section morphology of the Mg-8Al-0.2Mn alloy in Comparative Example 1 after being immersed in 3.5wt% NaCl solution for 2 days.

[0038] Figure 6Corrosion cross-section morphology of extruded Mg-8Al-0.1Gd-0.1Nd-0.1Er-0.2Mn alloy in 3.5wt% NaCl solution after immersion for 7 days. DETAILED DESCRIPTION

[0039] Various exemplary embodiments of the present application will now be described in detail, with reference to the figures. Such description, however, is to be considered in all respects only as illustrative, and not restrictive.

[0040] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. In addition, where particular ranges of values are given, it is meant to include every possible value within the range, as well as the range itself. Each smaller range that falls within the broader ranges is also a contemplated embodiment. The upper and lower limits of these smaller ranges can independently be included or excluded in the smaller ranges.

[0041] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although preferred methods and materials are described, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned herein are incorporated by reference to disclose and describe the methods and / or materials in connection with which the documents are cited. In case of conflict, the content of the present specification will control.

[0042] Various modifications and changes can be made to the specific embodiments of the present application described herein without departing from the scope or spirit of the application. Other embodiments of the application will be apparent to those of ordinary skill in the art from the description and examples presented herein. The description and examples are illustrative of the application and are not intended to limit the scope of the application.

[0043] As used herein, the terms "comprises", "comprising", "includes", "including", "has", "having", "contains", "containing", or variations thereof, are intended to be open-ended terms that mean including, but not limited to.

[0044] The embodiments of the present application provide a high corrosion-resistant magnesium alloy, the high corrosion-resistant magnesium alloy being a multi-element rare earth micro-alloyed and dispersion Mg 17 Al 12 The high corrosion-resistant magnesium alloy is synergistically controlled, and the chemical composition of the high corrosion-resistant magnesium alloy, in terms of mass percentage, is: Al: 7-9%, RE: 0.15-0.3%, Mn: 0.05-0.33%, and the balance being Mg and inevitable impurity elements; wherein RE is at least two of Gd, Nd and Er.

[0045] M-Al alloy is the most widely used commercial magnesium alloy at present, the addition of appropriate Al content can enhance the chemical stability of magnesium matrix, promote the passivation of the matrix surface and improve the corrosion resistance. On the other hand, the addition of excessive Al content will lead to the generation of a large number of network second phases in the alloy, reduce the mechanical properties and deformation processing ability of the alloy, and the addition of excessive Al will increase the allowable limit of impurity Fe in the matrix, which will damage the corrosion resistance. The addition of a small amount of Al has limited effect on the improvement of corrosion resistance, therefore the Al content in the high corrosion resistance magnesium alloy of the present application is in the range of 7-9wt%. The composite addition of trace amounts of rare earth elements Gd, Nd and Er can purify the magnesium melt and reduce the influence of impurity elements on corrosion resistance; on the other hand, the addition of trace amounts of rare earth elements can enhance the protection performance of the corrosion film layer, while the addition of a large amount of rare earth elements will lead to the formation of a large amount of high potential second phase containing rare earth elements, thereby accelerating the micro-electric corrosion. In addition, the addition of trace amounts of rare earth elements can control the cost of the alloy and is suitable for practical industrial applications. In addition, the addition of a small amount of Mn element can increase the allowable limit of impurity Fe element in the magnesium-aluminum alloy and reduce the influence of impurity Fe element on corrosion resistance, while the addition of excessive Mn will lead to the formation of a large amount of high potential second phase containing Mn, which will deteriorate the corrosion performance of the magnesium matrix.

[0046] In the embodiments of the present application, the inevitable impurity elements include Fe, Ni, Cu and Si, the Fe content is not more than 0.01wt%, the Ni content is not more than 0.002wt%, the Cu content is not more than 0.005wt%, and the Si content is not more than 0.05wt%.

[0047] The embodiments of the present application also provide a preparation method of the high corrosion resistance magnesium alloy, which comprises the following steps:

[0048] The pure magnesium ingot, the pure aluminum ingot, the Mg-Gd intermediate alloy, the Mg-Nd intermediate alloy, the Mg-Er intermediate alloy and the Mg-Mn intermediate alloy are weighed according to the chemical composition of the high corrosion resistance magnesium alloy, and preheating treatment is performed to remove moisture;

[0049] Under the protection of the protective gas, the pure magnesium ingot, the pure aluminum ingot, the Mg-Gd intermediate alloy, the Mg-Nd intermediate alloy, the Mg-Er intermediate alloy and the Mg-Mn intermediate alloy are mixed, heated and melted to obtain a magnesium alloy melt;

[0050] Under the protection of the protective gas, the magnesium alloy melt is refined, stirred, placed and heat preserved, and slag removal treatment is performed to obtain a purified magnesium alloy melt;

[0051] Under the protection of the protective gas, the purified magnesium alloy melt is cast into a preheated mold to obtain a magnesium alloy ingot;

[0052] The magnesium alloy ingot is subjected to homogenization treatment and then extruded into a plate.

[0053] The plate is directly aged or is subjected to solid solution treatment and then aged to obtain the high corrosion-resistant magnesium alloy.

[0054] In the embodiment of the present application, the protective gas is a mixture of SF6 and CO2, and the volume ratio of the two is 1:9.

[0055] In the embodiment of the present application, the step of obtaining the magnesium alloy melt is as follows:

[0056] Under the protection of the mixture of SF6 and CO2 (volume ratio of 1:9), the pure magnesium ingot is melted at 690℃, and then the Mg-Mn intermediate alloy is added in the range of 700-710℃ and stirred for 3-5 minutes;

[0057] Under the protection of the mixture of SF6 and CO2 (volume ratio of 1:9), the pure aluminum ingot is added in the range of 710-720℃, and then the pure aluminum ingot is kept for 10-20 minutes until it is melted to obtain the melt;

[0058] Under the protection of the mixture of SF6 and CO2 (volume ratio of 1:9), the slag on the surface of the melt is removed, the Mg-Gd intermediate alloy, the Mg-Nd intermediate alloy and the Mg-Er intermediate alloy are added in the range of 750-780℃, and the melt is kept for 10-20 minutes to obtain the magnesium alloy melt.

[0059] In the embodiment of the present application, the temperature for refining is 740-750℃, and the stirring time is 5-10 minutes.

[0060] In the embodiment of the present application, the step of standing and keeping is as follows: first standing and keeping at 740-750℃ for 30-40 minutes, and then cooling to 710-720℃ and standing and keeping for 40-50 minutes.

[0061] In the embodiment of the present application, the components of the refining agent are KCl 49wt%, CaCl2 24wt%, BaCl2 14wt%, CaF2 6wt% and YCl3 7wt%; and the adding amount of the refining agent is 1.5% of the total mass of the magnesium alloy melt.

[0062] In the embodiment of the present application, the temperature for casting is 690-710℃.

[0063] In the embodiment of the present application, the temperature for homogenization treatment is 350-400℃, and the time is 12-24 hours.

[0064] In the embodiment of the present application, the process of extruding into a plate is as follows: the extrusion temperature is 350-390℃, the extrusion speed is 1-1.5m / min, and the extrusion ratio is (10-30):1.

[0065] In the embodiment of the present application, when the aging treatment is directly performed, the temperature of the aging treatment is 200-300℃, and the time of the aging treatment is 24-72 hours.

[0066] In the embodiment of the present application, when the aging treatment is directly performed, the temperature of the aging treatment is 200-300℃, and the time of the aging treatment is 24-72 hours.

[0067] The present application also provides an application of the high-corrosion-resistant magnesium alloy in the field of lightweight and the equipment in the field of corrosion resistance.

[0068] For example, the high-corrosion-resistant magnesium alloy can be used to prepare aerospace equipment, automobiles and 3C electronic products.

[0069] In the following examples and comparative examples of the present application, the corrosion performance test method is as follows: the test solution is a neutral 3.5wt% NaCl solution, the test temperature is room temperature 25℃, the sample size is 20x20x5mm, the test time is 7 days, the immersion corrosion test refers to GB 10124-88 "Metal Material Laboratory Uniform Corrosion Immersion Test Method", and the weight loss rate is calculated by calculating the weight difference between the sample before the corrosion test and the sample after the corrosion test cleaning. The weight loss rate (mg / cm 2 / day) is equal to the weight difference divided by the sample surface area divided by the test days, which can be converted into the depth corrosion rate (mm / year) by the formula conversion. The volume of hydrogen gas generated by magnesium corrosion is equivalent to the decrease of the solution in the burette. The hydrogen evolution rate (mL / cm 2 / day) is obtained by dividing the volume of hydrogen gas by the sample surface area divided by the test days. The corrosion cleaning agent is 200g / L CrO3+10g / L AgNO3 (which is a general magnesium alloy corrosion product cleaning method), and the reference is GB / T 16545-2015 "Metal and Alloy Corrosion Removal of Corrosion Products on Corrosion Test Sample".

[0070] Unless otherwise specified, the room temperature in the present application is 25±2℃.

[0071] The raw materials used in the embodiments of the present application are all obtained by market purchase.

[0072] It should be noted that the details not described in the present application are all conventional operating means in the art, and are not the focus of the present application.

[0073] The technical solutions of the present application are further described below through examples.

[0074] Example 1

[0075] The embodiment provides a Mg-8Al-0.1Gd-0.1Nd-0.1Er-0.2Mn alloy based on multi-element rare earth micro-alloying and dispersion Mg 17 Al 12 The high corrosion-resistant magnesium alloy (which is a Mg-8Al-0.1Gd-0.1Nd-0.1Er-0.2Mn alloy) in a synergistically regulated manner has a chemical composition in percentage by mass as follows: Al: 8%, Gd: 0.1%, Nd: 0.1%, Er: 0.1%, Mn: 0.2%, and the balance of Mg and inevitable impurity elements, wherein the inevitable impurity elements are Fe, Ni, Cu and Si, and the total mass of the inevitable impurity elements is less than 0.08%; and the preparation method of the high corrosion-resistant magnesium alloy is as follows:

[0076] (1) pure magnesium ingots, pure aluminum ingots, Mg-30Gd intermediate alloy, Mg-30Nd intermediate alloy, Mg-30Er intermediate alloy and Mg-30Mn intermediate alloy corresponding to the alloy components are weighed and preheated to remove moisture;

[0077] (2) under the protection of SF6 and CO2 mixed gas (the volume ratio of the two is 1:9, the same below), the pure magnesium ingot is melted at 690 DEG C, then the Mg-30Mn intermediate alloy is added at 705 DEG C, and stirred for 5 minutes; the pure aluminum ingot is added at 715 DEG C, and then the aluminum ingot is heated for 15 minutes until the aluminum ingot is melted, the slag on the surface of the melt is removed, the Mg-30Gd intermediate alloy, the Mg-30Nd intermediate alloy and the Mg-30Er intermediate alloy are sequentially added at 755 DEG C, and the magnesium alloy melt is obtained after being heated for 15 minutes;

[0078] (3) under the protection of SF6 and CO2 mixed gas (the volume ratio of the two is 1:9, the same below), the magnesium alloy melt is refined at 745 DEG C (the composition of the refining agent is KCl 49wt%, CaCl2 24wt%, BaCl2 14wt%, CaF2 6wt% and YCl3 7wt%; the adding amount of the refining agent is 1.5% of the total mass of the magnesium alloy melt, the same below), and stirred for 10 minutes, then heated at 750 DEG C for 35 minutes, and finally cooled to 710 DEG C for 45 minutes for iron removal treatment, to obtain a purified magnesium alloy melt;

[0079] (4) under the protection of SF6 and CO2 mixed gas (the volume ratio of the two is 1:9, the same below), the furnace temperature is reduced to 700 DEG C, the slag on the surface of the melt is removed, and the magnesium alloy melt is cast into a preheated metal mold to obtain a magnesium alloy ingot;

[0080] (5) the obtained magnesium alloy ingot is subjected to homogenization treatment, the homogenization treatment temperature is 390°C, and the treatment time is 12 hours; then the ingot after the homogenization treatment is extruded into a plate at 350°C, the extrusion ratio is 15:1, and the extrusion speed is 1.5 m / min; then the extruded plate is subjected to solid solution-aging treatment, the solid solution temperature is 400°C, the solid solution time is 6 hours, the aging temperature is 200°C, and the aging time is 24 hours, to obtain the high-corrosion-resistant magnesium alloy, the weight loss rate, the hydrogen evolution rate and the corrosion rate of which are shown in Table 1.

[0081] It is detected that the actual chemical composition of the high-corrosion-resistant magnesium alloy in the embodiment is as follows: Al 8.1wt%, Gd 0.11wt%, Nd 0.12wt%, Er 0.10wt%, Mn 0.22wt%, inevitable impurities including Fe 0.0043wt%, Ni 0.0010wt%, Cu 0.0015wt% and Si 0.03wt%, and the balance being Mg.

[0082] Example 2

[0083] The embodiment provides a high-corrosion-resistant magnesium alloy based on multi-element rare earth micro-alloying and dispersion Mg 17 Al 12 The high-corrosion-resistant magnesium alloy (which is a Mg-8Al-0.15Gd-0.15Nd-0.2Mn alloy) is synergistically controlled, and the chemical composition of the high-corrosion-resistant magnesium alloy is as follows in terms of mass percentage: Al: 8%, Gd: 0.15%, Nd: 0.15%, Mn: 0.2%, the balance being Mg and inevitable impurity elements, wherein the inevitable impurity elements are Fe, Ni, Cu and Si, and the total mass of the inevitable impurity elements is less than 0.08%; and a preparation method of the high-corrosion-resistant magnesium alloy is as follows:

[0084] (1) pure magnesium ingots, pure aluminum ingots, Mg-30Gd intermediate alloy, Mg-30Nd intermediate alloy and Mg-30Mn intermediate alloy corresponding to the alloy components are weighed and subjected to preheating treatment to remove moisture;

[0085] (2) under the protection of SF6 and CO2 mixed gas, the pure magnesium ingot is melted at 690°C, then the Mg-30Mn intermediate alloy is added at 705°C, and stirring is performed for 5 minutes; the pure aluminum ingot is added at 715°C, and then heat preservation is performed for 15 minutes until the aluminum ingot is melted, the slag on the surface of the melt is removed, the Mg-30Gd intermediate alloy and the Mg-30Nd intermediate alloy are sequentially added at 755°C, and heat preservation is performed for 15 minutes, to obtain a magnesium alloy melt;

[0086] (3) under the protection of SF6 and CO2 mixed gas, refining the magnesium alloy melt at 750℃, stirring for 5 minutes, then standing and keeping warm at 750℃ for 30 minutes, finally reducing the temperature to 710℃ and standing for 40 minutes to carry out iron reduction treatment, to obtain the purified magnesium alloy melt;

[0087] (4) under the protection of SF6 and CO2 mixed gas, reducing the furnace temperature to 700℃, removing the slag on the surface of the melt, and casting the magnesium alloy melt into a preheated metal mold, to obtain a magnesium alloy ingot;

[0088] (5) carrying out homogenization treatment on the obtained magnesium alloy ingot, the homogenization treatment temperature is 390℃, and the treatment time is 12 hours; then extruding the homogenization treated ingot into a plate at 350℃, the extrusion ratio is 15:1, and the extrusion speed is 1.5 m / min; then carrying out solid solution and aging treatment on the extruded plate, the solid solution temperature is 420℃, the solid solution time is 5 hours, the aging temperature is 225℃, and the aging time is 24 hours, to obtain a high corrosion-resistant magnesium alloy, the weight loss rate, hydrogen evolution rate and corrosion rate of which are shown in Table 1.

[0089] It is detected that the actual chemical composition of the high corrosion-resistant magnesium alloy in the embodiment is as follows: Al 7.96wt%, Gd 0.14wt%, Nd 0.15wt%, Mn 0.25wt%, unavoidable impurities including Fe 0.0049wt%, Ni 0.0015wt%, Cu 0.0009wt% and Si 0.04wt%, and the balance being Mg.

[0090] Example 3

[0091] The embodiment provides a high corrosion-resistant magnesium alloy based on multi-element rare earth micro-alloying and dispersion Mg 17 Al 12 The high corrosion-resistant magnesium alloy (which is a Mg-8Al-0.15Gd-0.15Er-0.2Mn alloy) is synergistically controlled, and the chemical composition of the high corrosion-resistant magnesium alloy is as follows in terms of mass percentage: Al: 8%, Gd: 0.15%, Er: 0.15, Mn: 0.2%, the balance being Mg and unavoidable impurity elements, wherein the unavoidable impurity elements are Fe, Ni, Cu and Si, and the total mass of the unavoidable impurity elements is less than 0.02%; and a preparation method of the high corrosion-resistant magnesium alloy is as follows:

[0092] (1) weighing pure magnesium ingots, pure aluminum ingots, Mg-30Gd intermediate alloy, Mg-30Er intermediate alloy and Mg-30Mn intermediate alloy corresponding to the alloy components, and carrying out preheating treatment to remove moisture;

[0093] (2) under the protection of SF6 and CO2 mixed gas, melt the pure magnesium ingot at 690℃, then add the Mg-30Mn intermediate alloy at 710℃ and stir for 3 minutes; add the pure aluminum ingot at 710℃, then keep warm for 10 minutes until the aluminum ingot is melted, remove the slag on the surface of the melt, and then add the Mg-30Gd intermediate alloy and the Mg-30Er intermediate alloy at 750℃ in sequence and keep warm for 10 minutes to obtain a magnesium alloy melt;

[0094] (3) under the protection of SF6 and CO2 mixed gas, refine the magnesium alloy melt at 740℃ and stir for 10 minutes, then keep warm at 750℃ for 30 minutes, and finally reduce the temperature to 710℃ and keep warm for 40 minutes to perform iron reduction treatment to obtain a purified magnesium alloy melt;

[0095] (4) under the protection of SF6 and CO2 mixed gas, reduce the furnace temperature to 700℃, remove the slag on the surface of the melt, and then cast the magnesium alloy melt into a preheated metal mold to obtain a magnesium alloy ingot;

[0096] (5) perform homogenization treatment on the obtained magnesium alloy ingot, the homogenization treatment temperature is 390℃ and the treatment time is 12 hours; then extrude the homogenization-treated ingot into a plate at 350℃, the extrusion ratio is 15:1 and the extrusion speed is 1.5 m / min; then perform solid solution and aging treatment on the extruded plate, the solid solution temperature is 410℃, the solid solution time is 8 hours, the aging temperature is 200℃, and the aging time is 72 hours to obtain a high corrosion-resistant magnesium alloy, the weight loss rate, hydrogen evolution rate and corrosion rate of which are shown in Table 1.

[0097] It is detected that the actual chemical composition of the high corrosion-resistant magnesium alloy in the embodiment is as follows: Al 7.98wt%, Gd 0.13wt%, Er 0.15wt%, Mn 0.18wt%, unavoidable impurities including Fe 0.0051wt%, Ni 0.0013wt%, Cu 0.0010wt% and Si 0.025wt%, and the balance being Mg.

[0098] Example 4

[0099] The embodiment provides a high corrosion-resistant magnesium alloy based on multi-element rare earth micro-alloying and dispersion Mg 17 Al 12 The high corrosion-resistant magnesium alloy (which is a Mg-8Al-0.15Nd-0.15Er-0.2Mn alloy) has a chemical composition of Al: 8%, Nd: 0.15%, Er: 0.15%, Mn: 0.2%, the balance being Mg and unavoidable impurities, wherein the unavoidable impurities are Fe, Ni, Cu and Si, and the total mass of the unavoidable impurities is less than 0.08%; and a preparation method of the high corrosion-resistant magnesium alloy is as follows:

[0100] (1) The pure magnesium ingot, the pure aluminum ingot, the Mg-Nd intermediate alloy, the Mg-Er intermediate alloy and the Mg-30Mn intermediate alloy corresponding to the respective alloy components are weighed and preheated to remove moisture;

[0101] (2) The pure magnesium ingot is melted at 690℃ under the protection of SF6 and CO2 mixed gas, then the Mg-30Mn intermediate alloy is added at 700℃ and stirred for 5 minutes; the pure aluminum ingot is added at 720℃, then the aluminum ingot is kept for 20 minutes until it is melted, the slag on the surface of the melt is removed, the Mg-30Nd intermediate alloy and the Mg-30Er intermediate alloy are sequentially added at 760℃ and kept for 20 minutes, and a magnesium alloy melt is obtained;

[0102] (3) The magnesium alloy melt is refined at 750℃ under the protection of SF6 and CO2 mixed gas, stirred for 5 minutes, then kept for 40 minutes at 750℃, and finally cooled to 710℃ and kept for 50 minutes for iron reduction treatment, and a purified magnesium alloy melt is obtained;

[0103] (4) The furnace temperature is reduced to 700℃ under the protection of SF6 and CO2 mixed gas, the slag on the surface of the melt is removed, and the magnesium alloy melt is cast into a preheated metal mold to obtain a magnesium alloy ingot;

[0104] (5) The obtained magnesium alloy ingot is subjected to homogenization treatment at a homogenization temperature of 390℃ for 12 hours; then the homogenized ingot is extruded into a plate at 350℃, with an extrusion ratio of 15:1 and an extrusion speed of 1.5 m / min; then the extruded plate is directly subjected to aging treatment at an aging temperature of 300℃ for 24 hours, and a high corrosion-resistant magnesium alloy is obtained, the weight loss rate, hydrogen evolution rate and corrosion rate of which are shown in Table 1.

[0105] It is detected that the actual chemical composition of the high corrosion-resistant magnesium alloy in the embodiment is as follows: Al 8.10wt%, Nd: 0.17wt%, Er 0.16wt%, Mn 0.17wt%, unavoidable impurities including Fe 0.0055wt%, Ni 0.0008wt%, Cu 0.0016wt% and Si 0.045wt%, and the balance being Mg.

[0106] Comparative Example 1

[0107] The comparative example provides a magnesium alloy (which is Mg-8Al-0.2Mn alloy), and the chemical composition of the magnesium alloy is as follows in mass percentage: Al: 8%, Mn: 0.2%, and the balance of Mg and inevitable impurity elements, wherein the inevitable impurity elements are Fe, Ni, Cu and Si, and the total mass of the inevitable impurity elements is less than 0.08%; and the preparation method of the magnesium alloy is as follows:

[0108] (1) The pure magnesium ingot, the pure aluminum ingot and the Mg-30Mn intermediate alloy corresponding to the alloy components are weighed and preheated to remove moisture;

[0109] (2) The pure magnesium ingot is melted at 690°C under the protection of SF6 and CO2 mixed gas, then the Mg-30Mn intermediate alloy is added at 705°C and stirred for 5 minutes; the pure aluminum ingot is added at 715°C, and then the temperature is kept for 15 minutes until the aluminum ingot is melted to obtain a magnesium alloy melt;

[0110] (3) The magnesium alloy melt is refined at 745°C under the protection of SF6 and CO2 mixed gas, and stirred for 5-10 minutes, then kept at 750°C for 35 minutes, and finally reduced to 710°C for 45 minutes for iron reduction treatment to obtain a purified magnesium alloy melt;

[0111] (4) The furnace temperature is reduced to 700°C under the protection of SF6 and CO2 mixed gas, the slag on the surface of the melt is removed, and the magnesium alloy melt is cast into a preheated metal mold to obtain a magnesium alloy ingot;

[0112] (5) The obtained magnesium alloy ingot is subjected to homogenization treatment, the homogenization treatment temperature is 390°C, and the treatment time is 12 hours; then the homogenized ingot is extruded into a plate at 350°C, the extrusion ratio is 15:1, the extrusion speed is 1.5 m / min, and then the extruded plate is subjected to solid solution and aging treatment, the solid solution temperature is 400°C, the solid solution time is 6 hours, the aging temperature is 200°C, and the aging time is 24 hours to obtain a magnesium alloy, which is Mg-8Al-0.2Mn alloy, and the weight loss rate, hydrogen evolution rate and corrosion rate of the magnesium alloy are shown in Table 1.

[0113] It is detected that the actual chemical composition of the magnesium alloy in the comparative example is as follows: Al 8.20wt%, Mn 0.25wt%, inevitable impurities including Fe 0.0080wt%, Ni 0.00018wt%, Cu 0.0020wt% and Si 0.05wt%, and the balance of Mg.

[0114] Comparative Example 2

[0115] The present comparative example provides a magnesium alloy (which is Mg-8Al-0.2Gd-0.2Mn alloy), and the chemical composition of the magnesium alloy is as follows in terms of mass percentage: Al: 8%, Gd: 0.2%, Mn: 0.2%, and the balance of Mg and inevitable impurity elements, wherein the inevitable impurity elements are Fe, Ni, Cu and Si, and the total mass of the inevitable impurity elements is less than 0.08%; and the preparation method of the magnesium alloy is as follows:

[0116] (1) The pure magnesium ingot, the pure aluminum ingot, the Mg-30Gd intermediate alloy and the Mg-30Mn intermediate alloy corresponding to the alloy components are weighed and preheated to remove moisture;

[0117] (2) The pure magnesium ingot is melted at 690°C under the protection of SF6 and CO2 mixed gas, then the Mg-30Mn intermediate alloy is added at 705°C and stirred for 5 minutes; the pure aluminum ingot is added at 715°C, and then the aluminum ingot is kept for 15 minutes until it is melted, the slag on the surface of the melt is removed, the Mg-30Gd intermediate alloy is added at 755°C and kept for 15 minutes, and a magnesium alloy melt is obtained;

[0118] (3) The magnesium alloy melt is refined at 745°C under the protection of SF6 and CO2 mixed gas, stirred for 10 minutes, then kept for 35 minutes at 750°C, and finally cooled to 710°C and kept for 45 minutes for iron removal treatment, and a purified magnesium alloy melt is obtained;

[0119] (4) The furnace temperature is reduced to 700°C under the protection of SF6 and CO2 mixed gas, the slag on the surface of the melt is removed, and the magnesium alloy melt is cast into a preheated metal mold to obtain a magnesium alloy ingot.

[0120] (5) The obtained magnesium alloy ingot is subjected to homogenization treatment at a homogenization temperature of 390°C for 12 hours; then the homogenized ingot is extruded into a plate at 350°C with an extrusion ratio of 15:1 and an extrusion speed of 1.5 m / min; and then the extruded plate is subjected to solid solution and aging treatment at a solid solution temperature of 400°C for 6 hours, and an aging temperature of 200°C for 24 hours, to obtain a magnesium alloy, and the weight loss rate, hydrogen evolution rate and corrosion rate of the magnesium alloy are shown in Table 1.

[0121] It is detected that the actual chemical composition of the magnesium alloy in the present comparative example is as follows: Al 8.1wt%, Gd 0.22wt%, Mn 0.22wt%, inevitable impurities including Fe 0.0075wt%, Ni 0.0019wt%, Cu 0.0018wt% and Si 0.08wt%, and the balance of Mg.

[0122] Comparative Example 3

[0123] The present comparative example provides a magnesium alloy (which is Mg-8Al-0.2Nd-0.2Mn alloy), and the chemical composition of the magnesium alloy is: Al: 8%, Nd: 0.2%, Mn: 0.2%, and the balance is Mg and inevitable impurity elements, wherein the inevitable impurity elements are Fe, Ni, Cu and Si, and the total mass of the inevitable impurity elements is less than 0.08%; and the preparation method of the magnesium alloy is as follows:

[0124] (1) The pure magnesium ingot, the pure aluminum ingot, the Mg-30Nd intermediate alloy and the Mg-30Mn intermediate alloy corresponding to the alloy components are weighed and preheated to remove moisture;

[0125] (2) The pure magnesium ingot is melted at 690°C under the protection of SF6 and CO2 mixed gas, then the Mg-30Mn intermediate alloy is added at 705°C and stirred for 5 minutes; the pure aluminum ingot is added at 715°C, and then the aluminum ingot is kept for 15 minutes until it is melted, the slag on the surface of the melt is removed, the Mg-30Nd intermediate alloy is added at 755°C and kept for 15 minutes, and the magnesium alloy melt is obtained;

[0126] (3) The magnesium alloy melt is refined at 745°C under the protection of SF6 and CO2 mixed gas, stirred for 10 minutes, then kept for 35 minutes at 750°C, finally cooled to 710°C, kept for 45 minutes and subjected to iron removal treatment, and the purified magnesium alloy melt is obtained;

[0127] (4) Under the protection of SF6 and CO2 mixed gas, the furnace temperature is reduced to 700°C, the slag on the surface of the melt is removed, and the magnesium alloy melt is poured into a preheated metal mold to obtain a magnesium alloy ingot;

[0128] (5) The obtained magnesium alloy ingot is subjected to homogenization treatment, the homogenization treatment temperature is 390°C, and the treatment time is 12 hours; then the homogenized ingot is extruded into a plate at 350°C, the extrusion ratio is 15:1, and the extrusion speed is 1.5 m / min; then the extruded plate is subjected to solid solution and aging treatment, the solid solution temperature is 400°C, the solid solution time is 6 hours, the aging temperature is 200°C, and the aging time is 24 hours, and the magnesium alloy is obtained, and the weight loss rate, hydrogen evolution rate and corrosion rate of the magnesium alloy are shown in Table 1.

[0129] Through detection, the actual chemical composition of the magnesium alloy in the present comparative example is as follows: Al 8.1wt%, Nd 0.25wt%, Mn 0.21wt%, inevitable impurities including Fe 0.0079wt%, Ni 0.0015wt%, Cu 0.0016wt% and Si 0.07wt%, and the balance is Mg.

[0130] Comparative Example 4

[0131] The present comparative example provides a magnesium alloy (which is Mg-8Al-0.2Er-0.2Mn alloy), and the chemical composition of the magnesium alloy is as follows in terms of mass percentage: Al: 8%, Er: 0.2%, Mn: 0.2%, and the balance of Mg and inevitable impurity elements, wherein the inevitable impurity elements are Fe, Ni, Cu and Si, and the total mass of the inevitable impurity elements is less than 0.08%; and the preparation method of the magnesium alloy is as follows:

[0132] (1) pure magnesium ingots, pure aluminum ingots, Mg-30Er intermediate alloy and Mg-30Mn intermediate alloy corresponding to the alloy components are weighed and preheated to remove moisture;

[0133] (2) the pure magnesium ingots are melted at 690°C under the protection of SF6 and CO2 mixed gas, then the Mg-30Mn intermediate alloy is added at 705°C and stirred for 5 minutes; the pure aluminum ingots are added at 715°C, and then the aluminum ingots are kept for 15 minutes until the aluminum ingots are melted, the slag on the surface of the melt is removed, the Mg-30Er intermediate alloy is added at 755°C and kept for 15 minutes, and a magnesium alloy melt is obtained;

[0134] (3) the magnesium alloy melt is refined at 745°C under the protection of SF6 and CO2 mixed gas, stirred for 10 minutes, then kept for 35 minutes at 750°C, finally cooled to 710°C, kept for 45 minutes and subjected to iron removal treatment, and a purified magnesium alloy melt is obtained;

[0135] (4) under the protection of SF6 and CO2 mixed gas, the furnace temperature is reduced to 700°C, the slag on the surface of the melt is removed, and the magnesium alloy melt is cast into a preheated metal mold to obtain a magnesium alloy ingot;

[0136] (5) the obtained magnesium alloy ingot is subjected to homogenization treatment, the homogenization treatment temperature is 390°C, and the treatment time is 12 hours; then the homogenized ingot is extruded into a plate at 350°C, the extrusion ratio is 15:1, and the extrusion speed is 1.5 m / min; then the extruded plate is subjected to solid solution and aging treatment, the solid solution temperature is 400°C, the solid solution time is 6 hours, the aging temperature is 200°C, and the aging time is 24 hours, and a magnesium alloy is obtained, and the weight loss rate, hydrogen evolution rate and corrosion rate of the magnesium alloy are shown in Table 1.

[0137] It is detected that the actual chemical composition of the magnesium alloy in the present comparative example is as follows: Al 8.1wt%, Er 0.24wt%, Mn 0.25wt%, inevitable impurities including Fe 0.0080wt%, Ni 0.0016wt%, Cu 0.0018wt% and Si 0.06wt%, and the balance of Mg.

[0138] Comparative Example 5

[0139] This comparative example uses a commercial AZ91 magnesium alloy for comparison. The chemical composition of the magnesium alloy is: Al 8.96wt%, Zn 0.65wt%, Mn 0.28wt%, Fe 0.0072wt%, Ni 0.0012wt%, Cu 0.0015wt%, Si 0.05wt%, and the balance being Mg. The weight loss rate, hydrogen evolution rate and corrosion rate are shown in Table 1.

[0140] Comparative Example 6

[0141] This comparative example provides a magnesium alloy (which is a Mg-8Al-1Gd-1Nd-1Er-0.2Mn alloy), the chemical composition of which is, in mass percentage: Al: 8%, Gd: 1%, Nd: 1%, Er: 1%, Mn: 0.2%, the balance being Mg and inevitable impurity elements, wherein the inevitable impurity elements are Fe, Ni, Cu and Si, and the total mass of the inevitable impurity elements is less than 0.06%. The preparation method of the magnesium alloy is consistent with that of Example 1, and the weight loss rate, hydrogen evolution rate and corrosion rate are shown in Table 1.

[0142] It is detected that the actual chemical composition of the magnesium alloy in this comparative example is as follows: Al 8.05wt%, Gd 1.13wt%, Nd 1.05wt%, Er 1.08wt%, Mn 0.25wt%, inevitable impurities including Fe 0.0054wt%, Ni 0.0008wt%, Cu 0.0010wt% and Si 0.03wt%, and the balance being Mg.

[0143] Comparative Example 7

[0144] This comparative example is an extruded sheet of Mg-8Al-0.1Gd-0.1Nd-0.1Er-0.2Mn alloy in Example 1 without heat treatment regulation, and the weight loss rate, hydrogen evolution rate and corrosion rate are shown in Table 1. It is detected that the actual chemical composition of the magnesium alloy in this comparative example is as follows: Al 8.1wt%, Gd 0.11wt%, Nd 0.12wt%, Er 0.10wt%, Mn 0.22wt%, inevitable impurities including Fe 0.0043wt%, Ni 0.0010wt%, Cu 0.0015wt% and Si 0.03wt%, and the balance being Mg.

[0145] Table 1: Corrosion performance test results of magnesium alloys in each example and comparative example

[0146]

[0147]

[0148] From Table 1, it can be seen that the corrosion rate of the magnesium alloy in each embodiment of the present application is less than that of the magnesium alloy in each comparative example, and is much less than the corrosion rate of ultra-pure magnesium (0.25 mm / y, which is considered to be the intrinsic corrosion rate of magnesium) reported by Cao et al. in the article "Corrosion of ultra-high-purity Mg in 3.5% NaCl solution saturated with Mg(OH)2". It is found through literature search that the corrosion rate of the alloy reported at present is rarely lower than that of ultra-pure magnesium, thus proving that the magnesium alloy in the present application has excellent corrosion resistance. It can be seen that Comparative Example 1 is a magnesium alloy without rare earth elements, which exhibits an extremely high corrosion rate; Comparative Examples 2-4 are magnesium alloys with single rare earth element addition, and it can be seen that, compared with single rare earth element addition, the multiple rare earth element composite addition has better corrosion resistance, which is due to the composite rare earth oxide film formed and the refinement of multiple rare earth second phases. Comparative Example 6 is a magnesium alloy with excessive rare earth element addition, and it can be seen that the corrosion rate becomes larger. This is because, with the addition of a large amount of rare earth elements, a large amount of high-potential Al-RE phases will be produced in the magnesium matrix, leading to the intensification of the micro-electrochemical corrosion of the magnesium matrix, thus resulting in the decrease of corrosion resistance, and in addition, leading to the decrease of mechanical properties of the alloy. Comparative Example 7 is an alloy without heat treatment, and since no dispersed Mg 17 Al 12 phase organization is formed, the local corrosion of the alloy is more serious, thus resulting in the decrease of corrosion resistance.

[0149] Figure 1 The SEM microstructure of the high-corrosion-resistance magnesium alloy of Example 1 is shown in Figure 1, and it can be seen that the magnesium alloy contains a large amount of fine and dispersed Mg 17 Al 12 phase, and the other examples also have similar dispersed Mg 17 Al 12 phase organization.

[0150] Figure 2 The SEM microstructure of the magnesium alloy of Comparative Example 1 without rare earth element addition is shown in Figure 2. Compared with Figure 1 , Figure 2 the size of the Mg 17 Al 12 precipitated phase is larger, which shows that the composite addition of multiple rare earth elements in the present application effectively refines the size of the second phase, and changes the flaky and discontinuous Mg 17 Al 12 precipitated phase in the magnesium alloy of Comparative Example 1 into the fine and continuous Mg 17 Al 12 phase in Example 1. 17 Al12 The second phase can weaken the micro-electrode corrosion effect, so as to achieve the purpose of weakening the micro-electrode corrosion effect. In addition, the addition of a small amount of Gd, Nd and Er elements can form a composite rare earth corrosion product film layer, enhance the protection performance of the corrosion product film, and effectively purify the alloy melt, reduce the size of inclusions and make the distribution of inclusions more uniform. Therefore, the corrosion rate of the alloy in Example 1 is decreased by 130 times compared with the magnesium alloy in Comparative Example 1. In addition, it can be seen from Comparative Example 5 that the corrosion resistance of the corrosion-resistant magnesium alloy in the embodiment of the present application is much higher than that of the most widely used AZ91 alloy, which has great application prospect.

[0151] Figure 3 The microstructure of the extruded Mg-8Al-0.1Gd-0.1Nd-0.1Er-0.2Mn alloy without heat treatment regulation in Comparative Example 7. It can be seen that the second phase content in the alloy is less, and the microstructure is not fine and dispersed. Therefore, the corrosion rate of the magnesium alloy in Comparative Example 7 is much higher than that of the Mg 17 Al 12 phase structure magnesium alloy.

[0152] Figure 4 The corrosion section morphology of the high corrosion-resistant magnesium alloy in Example 1 after being immersed in 3.5wt% NaCl solution for 14 days can be seen. The Mg 17 Al 12 phase Mg-8Al-0.1Gd-0.1Nd-0.1Er-0.2Mn alloy exhibits uniform corrosion product film layer, and the thickness of the corrosion product film layer is only about 5μm, indicating excellent corrosion resistance. On the contrary, Figure 5 The corrosion section morphology of the Mg-8Al-0.2Mn alloy in Comparative Example 1 after being immersed in 3.5wt% NaCl solution for 2 days can be seen. It can be seen that the magnesium alloy in Comparative Example 1 has undergone serious localized corrosion, and the corrosion pit depth is about 190μm. In addition, it can be seen that the corrosion product of the magnesium alloy in Comparative Example 1 is loose and has a large number of cracks, indicating that the corrosion product does not have good protection performance.

[0153] Figure 6 The corrosion section morphology of the extruded Mg-8Al-0.1Gd-0.1Nd-0.1Er-0.2Mn alloy without heat treatment regulation in Comparative Example 7 after being immersed in 3.5wt% NaCl solution for 7 days can be seen. It can be seen that the extruded Mg 17 Al 12 phase Mg-8Al-0.1Gd-0.1Nd-0.1Er-0.2Mn alloy exhibits serious localized corrosion behavior, and the corrosion product is thick and contains a large number of cracks. In contrast, the Mg 17 Al 12The magnesium alloy in phase of embodiment 1 exhibits uniform corrosion behavior (as shown in Figure 4 due to the compact Mg 17 Al 12 promotes uniform corrosion of the magnesium matrix, and the compact corrosion product film formed effectively blocks the expansion of corrosion in the depth direction.

[0154] In summary, the present application realizes the design and development of high corrosion-resistant Mg-Al alloy by the method of complex addition of rare earth elements Gd, Nd and Er and the dispersion distribution of Mg 17 Al 12 The high corrosion-resistant magnesium alloy of the present application has the advantage of low cost, and has great application prospects in the fields of lightweight and corrosion resistance required by aerospace, electronic products, automobiles and the like.

[0155] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this, any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A high corrosion resistant magnesium alloy, characterized by, The high-corrosion-resistant magnesium alloy is based on multi-element rare earth micro-alloying and dispersed Mg 17 Al 12 The high-corrosion-resistant magnesium alloy is based on multi-element rare earth micro-alloying and dispersed Mg 17 Al 12 The high-corrosion-resistant magnesium alloy is based on multi-element rare earth micro-alloying and dispersed Mg 17 Al 12 The high-corrosion-resistant magnesium alloy is based on multi-element rare earth micro-alloying and dispersed Mg 17 Al 12 The high-corrosion-resistant magnesium alloy is based on multi-element rare earth micro-alloying and dispersed Mg 17 Al 12 The high-corrosion-resistant magnesium alloy is based on multi-element rare earth micro-alloying and dispersed Mg 17 Al 12 The high-corrosion-resistant magnesium alloy is based on multi-element rare earth micro-alloying and dispersed Mg 17 Al 12 The high-corrosion-resistant magnesium alloy is based on multi-element rare earth micro-alloying and dispersed Mg <000 2. A method for producing the high corrosion-resistant magnesium alloy according to claim 1, characterized by, The method comprises the following steps: According to the chemical composition of the high corrosion-resistant magnesium alloy, pure magnesium ingots, pure aluminum ingots, Mg-RE intermediate alloy and Mg-Mn intermediate alloy are weighed and preheated to remove moisture; The pure magnesium ingots, pure aluminum ingots, Mg-RE intermediate alloy and Mg-Mn intermediate alloy are mixed and heated to melt under the protection of a protective gas to obtain a magnesium alloy melt; The magnesium alloy melt is refined, stirred, placed and heat-insulated, and slagged under the protection of a protective gas to obtain a purified magnesium alloy melt; The purified magnesium alloy melt is cast into a preheated mold under the protection of a protective gas to obtain a magnesium alloy ingot; The magnesium alloy ingot is subjected to homogenization treatment and then extruded into a plate; The plate is directly subjected to aging treatment or is subjected to solid solution treatment and then aging treatment to obtain the high corrosion-resistant magnesium alloy.

3. The method of producing a high corrosion-resistant magnesium alloy according to claim 2, characterized by, The protective gas is a mixture of SF6 and CO2.

4. The method of producing a high corrosion-resistant magnesium alloy according to claim 2, characterized by, The step of obtaining the magnesium alloy melt is as follows: The pure magnesium ingots are melted at 690℃ under the protection of a mixture of SF6 and CO2, then the Mg-Mn intermediate alloy is added at 700-710℃ and stirred for 3-5 minutes; The pure aluminum ingots are added at 710-720℃ under the protection of a mixture of SF6 and CO2, then heat-insulated for 10-20 minutes until the pure aluminum ingots are melted to obtain a melt; The melt is slagged under the protection of a mixture of SF6 and CO2, the Mg-RE intermediate alloy is added at 750-780℃ and heat-insulated for 10-20 minutes to obtain the magnesium alloy melt.

5. The method of producing a high corrosion resistant magnesium alloy according to claim 4, characterized by, The volume ratio of SF6 to CO2 is 1:

9.

6. The method of producing a high corrosion resistant magnesium alloy according to claim 2, characterized by, The refining temperature is 740-750℃ and the stirring time is 5-10 minutes.

7. The method of producing a high corrosion resistant magnesium alloy according to claim 2, characterized by, The step of heat-insulating is to first heat-insulate at 740-750℃ for 30-40 minutes and then heat-insulate at 710-720℃ for 40-50 minutes after cooling.

8. The method of producing a high corrosion resistant magnesium alloy according to claim 2, characterized by, When the aging treatment is directly performed, the aging treatment temperature is 200-300℃ and the aging treatment time is 24-72 hours.

9. The method of producing a high corrosion resistant magnesium alloy according to claim 2, characterized by, When the aging treatment is performed after solid solution treatment, the solid solution treatment temperature is 400-420℃, the solid solution treatment time is 5-8 hours, the aging treatment temperature is 200-300℃ and the aging treatment time is 24-72 hours.

10. The high corrosion-resistant magnesium alloy according to claim 1 is applied in the field of lightweight and equipment in the field of corrosion resistance.

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