Magnesium alloy and method for producing the same, magnesium product and method for producing the same

Abstract

The application provides a magnesium alloy and a preparation method thereof, a magnesium product and a preparation method thereof. According to the mass percentage of the magnesium alloy, the magnesium alloy comprises the following components: 4-5% of Al, 1-4% of Ca, 1-4% of Y, 0.1-0.3% of Nd, 0.1-0.3% of Mn, and the balance of inevitable impurities and Mg elements. The magnesium alloy satisfies the following condition: 0.70A+1.18D>0.50E+0.01G+0.07I. The magnesium alloy provided by the application is designed by multi-element alloying and the proportion of each element is controlled, so that the micro-galvanic effect in the alloy and the macro-galvanic corrosion tendency when the alloy contacts with dissimilar metals are significantly reduced, and meanwhile, good die casting process performance is maintained.

Description

Technical Field

[0001] This invention belongs to the field of magnesium alloy technology, and particularly relates to a magnesium alloy and its preparation method, and magnesium products and their preparation methods. Background Technology

[0002] Magnesium alloys, as the lightest metallic structural materials, possess high specific strength, specific stiffness, excellent damping properties, and electromagnetic shielding performance, making them promising for applications in aerospace, automotive electronics, and 3C products. However, magnesium's extremely reactive chemical properties and low standard electrode potential (-2.363V) result in poor corrosion resistance, severely limiting the large-scale industrial application of magnesium alloys.

[0003] In the practical use of magnesium alloys, galvanic corrosion is one of the main forms of corrosion. When magnesium alloys come into contact with other metals (such as steel, aluminum alloys, etc.), macroscopic galvanic corrosion occurs because magnesium has a much lower potential than other metals, accelerating the corrosion failure of the magnesium alloy. Furthermore, microscopic galvanic corrosion can also occur between different phases within the magnesium alloy due to compositional differences. Specifically, the magnesium matrix has a lower potential, while the second phase (such as Mg) has a lower potential. 17 Al 12 (etc.) usually have a high potential, and the potential difference between the two can reach hundreds of millivolts, forming a micro-couple pair, which leads to preferential corrosion of the substrate.

[0004] In existing technologies, methods to improve the corrosion resistance of magnesium alloys mainly include: first, forming a protective layer on the surface through surface treatments such as passivation and micro-arc oxidation; and second, physical isolation, such as adding an insulating medium between the magnesium alloy and other metals. However, both surface treatment and physical isolation methods increase the process and cost, and once the coating or isolation layer is damaged, it can still cause severe localized corrosion.

[0005] Therefore, there is an urgent need for a magnesium alloy material that combines excellent corrosion resistance and low galvanic corrosion tendency. Summary of the Invention

[0006] One objective of this invention is to provide a magnesium alloy to solve the problem of poor corrosion resistance of existing magnesium alloys; a second objective is to provide a method for preparing a magnesium alloy; a third objective is to provide a magnesium product; and a fourth objective is to provide a method for preparing a magnesium product.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A magnesium alloy, by mass percentage, comprises the following components: 4-5% Al, 1-4% Ca, 1-4% Y, 0.1-0.3% Nd, 0.1-0.3% Mn, with the balance being unavoidable impurities and Mg.

[0009] The magnesium alloy satisfies the following condition: 0.70A+1.18D>0.50E+0.01G+0.07I, where A is the mass percentage of Al in the magnesium alloy, D is the mass percentage of Mn in the magnesium alloy, E is the mass percentage of Ca in the magnesium alloy, G is the mass percentage of Y in the magnesium alloy, and I is the mass percentage of Nd in the magnesium alloy.

[0010] Based on the above technical means, by precisely controlling the types and contents of each element in the raw materials, the strength and casting fluidity of the magnesium alloy can be guaranteed, while reducing microgalvanic corrosion in the alloy and improving the corrosion resistance of the alloy.

[0011] Furthermore, the magnesium alloy satisfies the following condition: I > (E + G) / 35, where E is the mass percentage of Ca in the magnesium alloy, G is the mass percentage of Y in the magnesium alloy, and I is the mass percentage of Nd in the magnesium alloy.

[0012] Based on the above technical means, by further controlling the mass ratio of Ca, Y and Nd elements in magnesium alloys, the synergistic effect of the three elements can be maximized, thereby improving the corrosion resistance of the alloy.

[0013] Furthermore, in the magnesium alloy, the ratio of the mass percentage of Ca to the mass percentage of Y is 1:(1-3).

[0014] Based on the above technical means, by further controlling the mass ratio of Ca and Y elements in magnesium alloys, the synergistic effect of the two elements can be maximized, thereby improving the corrosion resistance of the alloy.

[0015] Furthermore, the magnesium alloy comprises Al2Ca phase, Al2Y phase and Al2Nd phase.

[0016] Based on the above-mentioned technical means, the magnesium alloy includes the aforementioned low-potential Al2Ca phase, Al2Y phase, and finely dispersed Al2Nd phase, which can further reduce microgalvanic corrosion in the alloy and improve the corrosion resistance of the alloy.

[0017] Furthermore, the particle size of the Al2Ca phase is 3-20 μm; the particle size of the Al2Y phase is 5-15 μm.

[0018] The corrosion resistance of the alloy can be further improved using the aforementioned technical methods.

[0019] Furthermore, the particle size of the Al2Nd phase is 0.2-1 μm.

[0020] The corrosion resistance of the alloy can be further improved using the aforementioned technical methods.

[0021] A second aspect of the present invention provides a method for preparing a magnesium alloy, comprising the following steps:

[0022] S1: In a protective atmosphere, raw materials including magnesium source, aluminum source, manganese source, calcium source, yttrium source and niobium source are melted and mixed to obtain a mixed melt;

[0023] S2: The mixed melt is refined to obtain the magnesium alloy.

[0024] According to the above-mentioned technical means, melting and mixing under a protective atmosphere can effectively reduce the oxidation reaction and burn-off of magnesium and active alloying elements at high temperatures, allowing Al, Mn, Ca, Y and niobium to stably enter the magnesium-based melt and form a uniform solid solution and fine second phase distribution. Subsequently, refining treatment removes oxide films, inclusions and dissolved gases from the melt, which can reduce the local corrosion sources induced by defects during solidification.

[0025] Furthermore, the specific steps of the refining process include: adding a refining agent to the mixed melt for refining.

[0026] Furthermore, the specific steps for melting and mixing raw materials including magnesium, aluminum, manganese, calcium, yttrium, and niobium sources include the following:

[0027] In a protective atmosphere, a magnesium source is first melted; then an aluminum source, a manganese source, a calcium source, a yttrium source, and a niobium source are added, kept at a constant temperature, and after melting, the molten metal is stirred evenly to obtain the mixed melt.

[0028] According to the above technical means, the magnesium source is melted first and then the other raw materials are added sequentially or simultaneously. This is to use the magnesium liquid as a continuous phase to promote the rapid wetting and diffusion of each element, and to reduce the floating, sinking or local enrichment of elements such as calcium, yttrium, and niobium due to density differences. Then, the material is kept warm and stirred, which can make the raw materials fully melted and evenly dispersed to form a mixed melt with stable composition.

[0029] A third aspect of the present invention provides a magnesium article, which is prepared from the magnesium alloy described in the first aspect above.

[0030] Furthermore, the salt spray corrosion rate of the magnesium product is 0.3-0.54 mm / year; the salt spray corrosion rate of the 304 stainless steel galvanometer of the magnesium product is 1.0-1.6 mm / year.

[0031] Based on the above-mentioned technical means, magnesium products have a lower corrosion rate and galvanic corrosion rate.

[0032] The fourth aspect of the present invention provides a method for preparing a magnesium product, comprising: sequentially performing a melting treatment and a die-casting treatment on the magnesium alloy to obtain the magnesium product.

[0033] Furthermore, the melting temperature is 690-730℃.

[0034] The beneficial effects of this invention are:

[0035] The magnesium alloy provided by this invention, through precise control of the types and contents of each element in the raw materials, ensures the strength and casting fluidity of the magnesium alloy, while reducing microgalvanic corrosion in the alloy and improving the corrosion resistance of the alloy. Attached Figure Description

[0036] Figure 1 The image shows a photograph of the die-cast magnesium product obtained in Example 1 of this invention after a salt spray corrosion test.

[0037] Figure 2 This is a photograph of the die-cast magnesium product obtained in Comparative Example 1 of this invention after a salt spray corrosion test;

[0038] Figure 3 This is a photograph of the die-cast magnesium product obtained in Comparative Example 2 of this invention after a salt spray corrosion test;

[0039] Figure 4 This is a photograph of the die-cast magnesium product obtained in Example 1 of the present invention after a salt spray corrosion test by a 304 stainless steel galvanometer.

[0040] Figure 5 This is a photograph of the die-cast magnesium product obtained in Comparative Example 1 of the present invention after a salt spray corrosion test by a 304 stainless steel galvanometer.

[0041] Figure 6 This is a photograph of the die-cast magnesium product obtained in Comparative Example 2 of the present invention after a salt spray corrosion test by a 304 stainless steel galvanometer.

[0042] Figure 7 This is a SEM image of the die-cast magnesium product obtained in Example 1 of the present invention. Detailed Implementation

[0043] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0044] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0045] To further improve the overall performance of magnesium alloys, the inventors studied existing magnesium alloys and discovered that galvanic corrosion is one of the main forms of corrosion during actual use. When magnesium alloys come into contact with other metals (such as steel and aluminum alloys), macroscopic galvanic corrosion occurs because magnesium has a much lower potential than other metals, accelerating the corrosion failure of the magnesium alloy. Furthermore, microscopic galvanic corrosion also occurs between different phases within the magnesium alloy due to compositional differences. Specifically, the magnesium matrix has a lower potential, while the second phase (such as Mg) has a lower potential. 17 Al 12 (etc.) usually have a high potential, and the potential difference between the two can reach hundreds of millivolts, forming a micro-couple pair, which leads to preferential corrosion of the substrate.

[0046] Based on this, the first aspect of the present invention provides a magnesium alloy, which, according to the mass percentage of the magnesium alloy, comprises the following components: 4-5% Al, 1-4% Ca, 1-4% Y, 0.1-0.3% Nd, 0.1-0.3% Mn, with the balance being unavoidable impurities and Mg.

[0047] Magnesium alloys satisfy the following condition: 0.70A+1.18D>0.50E+0.01G+0.07I, where A is the mass percentage of Al in the magnesium alloy, D is the mass percentage of Mn in the magnesium alloy, E is the mass percentage of Ca in the magnesium alloy, G is the mass percentage of Y in the magnesium alloy, and I is the mass percentage of Nd in the magnesium alloy.

[0048] For example, the mass percentage of Al in the magnesium alloy is 4%, 4.2%, 4.4%, 4.6%, 4.8% or 5%, or a range of any two of these values.

[0049] For example, the mass percentage of Ca in the magnesium alloy is 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, 2.4%, 2.6%, 2.8%, 3.0%, 3.2%, 3.4%, 3.6%, 3.8%, or 4.0%, or a range of any two of these values.

[0050] For example, the mass percentage of Y element in the magnesium alloy is 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, 2.4%, 2.6%, 2.8%, 3.0%, 3.2%, 3.4%, 3.6%, 3.8%, or 4.0%, or a range of any two of these values.

[0051] For example, the mass percentage of Nd in the magnesium alloy is 0.1%, 0.12%, 0.14%, 0.16%, 0.18%, 0.2%, 0.22%, 0.24%, 0.26%, 0.28%, or 0.3%, or a range of any two of these values.

[0052] For example, the mass percentage of Mn in the magnesium alloy is 0.1%, 0.12%, 0.14%, 0.16%, 0.18%, 0.2%, 0.22%, 0.24%, 0.26%, 0.28%, or 0.3%, or a range of any two of these values.

[0053] The magnesium alloy provided by this invention possesses both excellent corrosion resistance and low galvanic corrosion tendency, for the following reasons:

[0054] Firstly, Al, as a major alloying element, ensures the strength and casting fluidity of the alloy. However, this invention controls the Al content at 4-5%, lower than traditional die-cast magnesium alloys such as AM60 and AZ91. This is mainly to control the content of the second phase in the alloy, reduce microgalvanic corrosion, and improve the alloy's corrosion resistance. When the Al content is too low, it is difficult to effectively support the overall potential and casting performance of the alloy, and it is also not conducive to the subsequent formation of aluminum-based intermetallic compounds with Ca and Y, which are more beneficial to corrosion resistance. On the other hand, when the Al content is too high, it is easy to increase the probability of the formation of high-potential second phase, increase the micropotential difference between the matrix and the second phase, and cause the corrosion process to occur preferentially along the local uneven structure regions.

[0055] Secondly, by adding Ca and Y elements, which combine with Al elements, the high potential β-Mg in traditional magnesium alloys is suppressed. 17 Al 12 The formation of the phase, and the formation of the low-potential Al2Ca / Al2Y phase, further reduces microgalvanic corrosion in the alloy and improves the corrosion resistance of the alloy.

[0056] Specifically, the Ca content is limited to 1-4% because Ca preferentially forms relatively low-potential phases such as Al2Ca with Al, and the potential matching between this type of phase and the magnesium matrix is ​​better than that of β-Mg. 17 Al 12Rare earth elements (REEs) can reduce corrosion driving forces and help change the morphology and distribution of the second phase during solidification, making the microstructure more dispersed and stable. When the Ca content is below 1%, the above-mentioned regulatory effect is weak; when the Ca content is above 4%, it may lead to problems such as an increase in coarse second phases, decreased fluidity, and increased local brittleness, which is detrimental to the overall performance of die-cast parts. Rare earth elements (Y) are limited to the range of 1-4% and are mainly used to synergistically form phases such as Al2Y, which have high thermal stability and milder electrochemical behavior. Y can also reduce local component segregation and make the second phase distribution finer and more uniform through the purification and modification effects of rare earth elements on the microstructure. When Y is less than 1%, its contribution to microstructure stability and potential regulation is limited; when Y exceeds 4%, it may lead to increased costs, overly complex phase composition, and affect the economy and stability of the die-casting process.

[0057] Furthermore, this invention adds the rare earth element Nd. Nd has high solid solubility in Mg and is the rare earth element with the closest electrode potential to Mg. Nd has two main effects: first, it can dissolve in the Mg matrix, increasing the electrode potential of the Mg matrix and reducing the potential difference between the Mg matrix and the second phase; second, Nd can form fine and dispersed second phases such as Al2Nd and Mg5Nd, significantly refining the alloy microstructure. The finer second phases are more evenly distributed, avoiding concentrated localized corrosion. The fine grains also help form a uniform and continuous corrosion product film, improving the overall corrosion resistance of the alloy. The Nd content is controlled at 0.1% to 0.3%, mainly utilizing its trace rare earth effect to improve the uniformity of the matrix microstructure and, to some extent, improve the matrix potential level through solid solution strengthening, grain refinement, and auxiliary refinement of the second phase. If Nd is below 0.1%, its refining and potential correction effects are not significant; if it is above 0.3%, it can easily cause unnecessary phase structure complexity.

[0058] In addition, this study also added manganese (Mn), with the Mn content controlled between 0.1% and 0.3%. Besides working with other elements in the system to regulate the overall potential, Mn also plays a role in purifying harmful impurities, especially Fe-based impurities. Mn can reduce the catalytic effect of impurities on corrosion, thereby inhibiting pitting corrosion initiation. When Mn content is less than 0.1%, the purification and potential regulation effects are limited; when it exceeds 0.3%, it may cause new phase precipitation or process stability problems.

[0059] Finally, 0.70A + 1.18D > 0.50E + 0.01G + 0.07I is not merely a mathematical expression, but rather an engineering-based criterion for defining the comprehensive contribution of the aforementioned elements to the overall potential equilibrium of the alloy. Specifically:

[0060] The standard electrode potentials of Mg, Al, Ca, Y, Nd, and Mn are -2.363V, -1.662V, -2.866V, -2.373V, -2.431V, and -1.180V, respectively. The standard electrode potential differences between Al, Ca, Y, Nd, Mn, and Mg are approximately 0.701V, -0.503V, -0.010V, -0.070V, and 1.183V, respectively. Therefore, this invention further specifies that the elements Al, Ca, Y, Nd, and Mn must satisfy the following condition: 0.70A + 1.18D > 0.50E + 0.01G + 0.07I, where A is the mass percentage of Al in the magnesium alloy, D is the mass percentage of Mn in the magnesium alloy, E is the mass percentage of Ca in the magnesium alloy, G is the mass percentage of Y in the magnesium alloy, and I is the mass percentage of Nd in the magnesium alloy. This condition uses the standard electrode potential of pure Mg (-2.363 V) as the critical threshold. The goal is to ensure that the overall corrosion potential of the alloy is higher than this threshold, thereby reducing the potential difference between magnesium alloys and commonly used industrial metals such as steel and aluminum alloys from a thermodynamic perspective, and reducing the driving force of macroscopic galvanic corrosion. The coefficients of each element in the formula are the engineered rounded values ​​of the potential difference between the standard electrode potential of that element and that of pure Mg. To ensure that the overall potential of the alloy is higher than that of pure Mg, the sum of the positive contribution terms corresponding to Al and Mn must be greater than the sum of the influence terms corresponding to Ca, Y, and Nd, making the total potential shift of the alloy positive. Under this condition, the overall electrode potential of the alloy can be higher than that of magnesium itself (-2.363 V), improving the alloy's galvanic corrosion resistance.

[0061] In one specific embodiment, the magnesium alloy satisfies the following condition: I > (E + G) / 35, where E is the mass percentage of Ca in the magnesium alloy, G is the mass percentage of Y in the magnesium alloy, and I is the mass percentage of Nd in the magnesium alloy.

[0062] This invention further specifies that Ca, Y, and Nd elements must meet the following condition: I > (E+G) / 35. After Nd enters the magnesium matrix, it preferentially participates in solid solution and forms a finely dispersed Nd-containing second phase, thereby increasing the local matrix potential and weakening the galvanic effect between the coarse second phase and the Mg matrix. Simultaneously, Nd, together with Ca and Y, influences segregation behavior during solidification, promoting a finer and more uniform microstructure and reducing corrosion-sensitive enrichment zones. By constraining I > (E+G) / 35, the coarsening of the second phase and potential mismatch caused by insufficient Nd after increasing Ca and Y content can be avoided, resulting in a more harmonious electrochemical environment within the alloy. This process achieves corrosion channel suppression at the alloy body level, rather than relying on an external surface protective layer. Therefore, when die-cast parts are used in humid, salt spray, and dissimilar metal contact environments, it can reduce the probability of microscopic and macroscopic galvanic corrosion.

[0063] In one specific embodiment, the mass percentage ratio of Ca to Y in the magnesium alloy is 1:(1-3).

[0064] For example, the ratio of the mass percentage of Ca to the mass percentage of Y is 1:1, 1:1.5, 1:2, 1:2.5, 1:3, or a range of any two of these values.

[0065] The present invention also limits the mass percentage ratio of Ca to Y to be 1:(1-3). Ca can preferentially form relatively low potential phases such as Al2Ca with Al, while Y can synergistically form phases such as Al2Y with Al, which have higher thermal stability and milder electrochemical behavior. Therefore, by using the constraint that the mass percentage ratio of Ca to Y is 1:(1-3), the amount of Al2Ca and Al2Y phases generated can be balanced, and the corrosion resistance of magnesium alloy can be further adjusted.

[0066] In one specific embodiment, the magnesium alloy comprises Al2Ca phase, Al2Y phase, and Al2Nd phase. The magnesium alloy microstructure of the present invention simultaneously contains Al2Ca, Al2Y, and Al2Nd phases. These phases do not exist in isolation but are synergistically distributed within the magnesium matrix. The Al2Ca phase, formed by the preferential combination of Al and Ca, can reduce the continuity of the locally high-potential second phase and weaken the channels through which corrosive media preferentially propagate along grain boundaries. The Al2Y phase, formed by Al and Y, has high thermal stability and is typically distributed in a fine, dispersed morphology within the grains or near grain boundaries, contributing to microstructure stability and mitigating the driving force of galvanic corrosion. The Al2Nd phase, formed by Al and Nd, can further refine the size of the second phase and improve the interphase spacing, making it more difficult for corrosion reactions to concentrate locally.

[0067] In one specific embodiment, the Al2Ca phase has a particle size of 3-20 μm, and the Al2Y phase has a particle size of 5-15 μm. By controlling these two types of phases within a small size range, they can be uniformly dispersed in the matrix, reducing localized microgalvanic corrosion caused by interphase potential differences and decreasing stress concentration at the interface between the second phase and the matrix.

[0068] In one specific embodiment, the particle size of the Al2Nd phase is 0.2-1 μm. As an Nd-containing precipitate, if the particle size of the Al2Nd phase is too large, it is easy to form local enrichment zones at grain boundaries or within grains, becoming preferential corrosion initiation points. Therefore, controlling the particle size of the Al2Nd phase to a smaller range can promote its uniform distribution in the matrix, enhance the pinning effect on grains, inhibit microstructure coarsening, and reduce the driving force of microgalvanic corrosion.

[0069] A second aspect of the present invention provides a method for preparing a magnesium alloy, comprising:

[0070] S1: In a protective atmosphere, raw materials including magnesium source, aluminum source, manganese source, calcium source, yttrium source and niobium source are melted and mixed to obtain a mixed melt;

[0071] S2: The mixed melt is refined to obtain a magnesium alloy.

[0072] This invention involves melting and mixing under a protective atmosphere, which can effectively reduce the oxidation reaction and burn-off of magnesium and active alloying elements at high temperatures. This allows Al, Mn, Ca, Y, and niobium to stably enter the magnesium-based melt and form a uniform solid solution and fine second phase distribution. Subsequently, refining treatment removes oxide films, inclusions, and dissolved gases from the melt, which can reduce the sources of localized corrosion induced by defects during solidification.

[0073] In this invention, the aluminum source refers to a raw material that provides aluminum, the magnesium source refers to a raw material that provides magnesium, the manganese source refers to a raw material that provides manganese, the calcium source refers to a raw material that provides calcium, the yttrium source refers to a raw material that provides yttrium, and the niobium source refers to a raw material that provides niobium. The magnesium, aluminum, manganese, calcium, yttrium, and niobium sources can be elemental or alloys.

[0074] In one specific embodiment, Mg and Al are prepared in the form of pure magnesium and pure aluminum, Mn is prepared in the form of Al-10Mn master alloy, Ca is prepared in the form of Mg-30Ca master alloy, Y is prepared in the form of Mg-30Y master alloy, and Nd is prepared in the form of Mg-10Nd master alloy.

[0075] The present invention does not specifically limit the type of protective atmosphere. In one embodiment, the protective atmosphere is selected from at least one of N2, CO2, and SF6 gases.

[0076] When the protective atmosphere is the above mixture, the present invention does not specifically limit the proportion of each substance in the mixture.

[0077] In one specific embodiment, the protective atmosphere is a mixture of N2 and SF6, wherein the volume percentage of N2 in the mixture is 99.7%-99.9%. Under this protective atmosphere, the mixed melt composition is homogeneous, elemental loss is minimal, and oxide inclusions are reduced.

[0078] This invention does not specifically limit the equipment used to prepare the mixed melt; conventional smelting equipment in the art, such as a smelting furnace, is sufficient.

[0079] This invention does not impose any special limitations on the specific model and source of the smelting furnace; any commercially available smelting furnace known to those skilled in the art can be used.

[0080] This invention does not specifically limit the method for preparing the mixed melt.

[0081] In one embodiment, the specific steps of melting and mixing raw materials including magnesium source, aluminum source, manganese source, calcium source, yttrium source and niobium source include the following:

[0082] In a protective atmosphere, the magnesium source is first melted; then aluminum, manganese, calcium, yttrium and niobium sources are added, kept at a constant temperature, and after melting, the molten metal is stirred evenly to obtain a mixed melt.

[0083] The present invention first melts the magnesium source and then adds the other raw materials sequentially or simultaneously. This is to use the magnesium liquid as a continuous phase to promote the rapid wetting and diffusion of each element, and to reduce the floating, sinking or local enrichment of elements such as calcium, yttrium, and niobium due to density differences. Then, the material is kept warm and stirred, which can make the raw materials fully melt and evenly dispersed to form a stable mixed melt.

[0084] In one embodiment, the heat preservation temperature is 740-760℃, and the heat preservation time is 30-60 minutes.

[0085] In one embodiment, the refining process includes adding a refining agent to the mixed melt for refining.

[0086] In one specific embodiment, the amount of refining agent added is 2%-3% of the weight of the mixed melt. Within this range, a balance between refining effect and economy can be achieved.

[0087] This invention does not specifically limit the type of refining agent; conventional refining agents in the art can be used.

[0088] In one embodiment, the refining agent in the refining process is a mixture of MgCl2, KCl, CaF2, NaCl, and light magnesium carbonate. This refining agent has a better purification effect on the melt.

[0089] In one embodiment, in the mixture of MgCl2, KCl, CaF2, NaCl and light magnesium carbonate, the mass percentage of MgCl2 is 36-44%, the mass percentage of KCl is 22-28%, the mass percentage of CaF2 is 15-20%, the mass percentage of NaCl is 12-18%, the mass percentage of light magnesium carbonate is 5%, and the sum of the mass percentages of MgCl2, KCl, CaF2, NaCl and light magnesium carbonate is 100%.

[0090] In one specific embodiment, the refining process is carried out at a temperature of 720~740 ℃. At this temperature, the refining process achieves better technical results.

[0091] For example, the refining temperature is 720 ℃, 725 ℃, 730 ℃, 735 ℃, 740 ℃, or a range of any two of these values.

[0092] A third aspect of the present invention provides a magnesium article comprising the magnesium alloy described above, or a magnesium alloy prepared by the preparation method described above.

[0093] In one specific embodiment, the salt spray corrosion rate of the magnesium product is 0.3-0.54 mm / year; the salt spray corrosion rate of the 304 stainless steel galvanic electrode of the magnesium product is 1.0-1.6 mm / year. The magnesium product of the present invention has a low corrosion rate and a low galvanic electrode corrosion rate.

[0094] For example, the salt spray corrosion rate of magnesium products is 0.3 mm / year, 0.32 mm / year, 0.34 mm / year, 0.36 mm / year, 0.38 mm / year, 0.4 mm / year, 0.54 mm / year, or a range of any two of these values.

[0095] For example, the galvanic corrosion rate of 304 stainless steel for magnesium products is 1.0 mm / year, 1.05 mm / year, 1.1 mm / year, 1.15 mm / year, 1.2 mm / year, 1.25 mm / year, 1.30 mm / year, 1.35 mm / year, 1.4 mm / year, 1.45 mm / year, 1.5 mm / year, 1.6 mm / year, or a range of any two of these values.

[0096] The fourth aspect of the present invention provides a method for preparing magnesium products, comprising: sequentially performing melting treatment and die casting treatment on a magnesium alloy to obtain magnesium products.

[0097] This invention does not impose specific limitations on the conditions for melting and die casting, and those skilled in the art can make adjustments according to specific needs.

[0098] In one specific embodiment, the melting temperature is 690-730°C. Within this temperature range, the magnesium alloy can be rapidly and completely melted.

[0099] For example, the melting temperature is 690°C, 695°C, 700°C, 705°C, 710°C, 715°C, 720°C, 725°C, 730°C, or a range of any two of these values.

[0100] In one specific embodiment, the parameters of the die casting process include: injection speed 4-6 m / s, vacuum degree ≤100 mbar, mold temperature 150℃-200℃, injection specific pressure 80-100 MPa, and holding time 10-15 s.

[0101] The present invention will be further described below through specific embodiments.

[0102] Example 1

[0103] The weight percentage of each element in the die-cast magnesium product of this embodiment is as follows: 4.5% Al, 2% Ca, 2% Y, 0.2% Nd, 0.2% Mn; the total amount of other impurities is ≤0.1%, and the balance is Mg.

[0104] The preparation method of the die-cast magnesium product in this embodiment is as follows:

[0105] (1) Prepare materials according to the above formula composition; wherein, Mg and Al are prepared in the form of pure magnesium and pure aluminum, Mn is prepared in the form of Al-10Mn intermediate alloy, Ca is prepared in the form of Mg-30Ca intermediate alloy, Y is prepared in the form of Mg-30Y intermediate alloy, and Nd is prepared in the form of Mg-10Nd intermediate alloy.

[0106] (2) First, place pure magnesium in a melting furnace and introduce a mixture of N2 and SF6 gas (in which nitrogen accounts for 99.7% of the volume) and melt it at 740°C; then add pure aluminum, Al-10Mn master alloy, Mg-30Ca master alloy, Mg-30Y master alloy and Mg-10Nd master alloy, and keep it at 750°C for 60 minutes. After melting, stir the molten metal evenly to obtain a mixed melt.

[0107] (3) Refining agent powder is added to the mixed melt at 730 °C for refining treatment. The amount of refining agent added is 2.5% of the weight of the mixed melt. Slag is removed to obtain magnesium alloy. The refining agent is a mixture of MgCl2, KCl, CaF2, NaCl and light magnesium carbonate, wherein the mass percentage of MgCl2 is 40%, the mass percentage of KCl is 25%, the mass percentage of CaF2 is 15%, the mass percentage of NaCl is 15%, and the mass percentage of light magnesium carbonate is 5%.

[0108] (4) The magnesium alloy is melted at 710 °C and die-cast to obtain magnesium products. The die-casting process parameters are: injection speed 5 m / s, vacuum degree 90 mbar, mold temperature 170 °C, injection pressure 90 MPa, and holding time 13 s.

[0109] Example 2

[0110] The weight percentage of each element in the die-cast magnesium product of the embodiment is as follows: 4.2% Al, 1% Ca, 3% Y, 0.12% Nd, 0.15% Mn; the total amount of other impurities is ≤0.1%, and the balance is Mg.

[0111] The preparation method of the die-cast magnesium product in this embodiment is as follows:

[0112] (1) Prepare materials according to the formula composition; among them, Mg and Al are prepared in the form of pure magnesium and pure aluminum, Mn is prepared in the form of Al-10Mn master alloy, Ca is prepared in the form of Mg-30Ca master alloy, Y is prepared in the form of Mg-30Y master alloy, and Nd is prepared in the form of Mg-10Nd master alloy.

[0113] (2) First, place pure magnesium in a melting furnace and introduce a mixture of N2 and SF6 gas (in which nitrogen accounts for 99.7% of the volume) and melt it at 740°C; then add pure aluminum, Al-10Mn master alloy, Mg-30Ca master alloy, Mg-30Y master alloy and Mg-10Nd master alloy, and keep it at 750°C for 40 minutes. After melting, stir the molten metal evenly to obtain a mixed melt.

[0114] (3) Refining agent powder is added to the mixed melt at 720 °C for refining treatment and slag removal to obtain magnesium alloy; wherein the refining agent is a mixture of MgCl2, KCl, CaF2, NaCl and light magnesium carbonate, wherein the mass percentage of MgCl2 is 40%, the mass percentage of KCl is 25%, the mass percentage of CaF2 is 15%, the mass percentage of NaCl is 15%, and the mass percentage of light magnesium carbonate is 5%.

[0115] (4) The magnesium alloy is melted at 690 ℃ and die-cast to obtain magnesium products. The die-casting process parameters are: injection speed 5m / s, vacuum degree 90mbar, mold temperature 170℃, injection pressure 90MPa, and holding time 13s.

[0116] Example 3

[0117] The weight percentage of each element in the die-cast magnesium product of the embodiment is as follows: 4.7% Al, 1% Ca, 2% Y, 0.3% Nd, 0.1% Mn; the total amount of other impurities is ≤0.1%, and the balance is Mg.

[0118] The preparation method of the die-cast magnesium product in this embodiment is as follows:

[0119] (1) Prepare materials according to the formula composition; among them, Mg and Al are prepared in the form of pure magnesium and pure aluminum, Mn is prepared in the form of Al-10Mn master alloy, Ca is prepared in the form of Mg-30Ca master alloy, Y is prepared in the form of Mg-30Y master alloy, and Nd is prepared in the form of Mg-10Nd master alloy.

[0120] (2) First, place pure magnesium in a melting furnace and introduce a mixture of N2 and SF6 gas (in which nitrogen accounts for 99.7% of the volume) and melt it at 740°C; then add pure aluminum, Al-10Mn master alloy, Mg-30Ca master alloy, Mg-30Y master alloy and Mg-10Nd master alloy, and keep it at 740°C for 30 minutes. After melting, stir the molten metal evenly to obtain a mixed melt.

[0121] (3) Refining agent powder is added to the mixed melt at 740 °C for refining treatment and slag removal to obtain magnesium alloy; wherein the refining agent is a mixture of MgCl2, KCl, CaF2, NaCl and light magnesium carbonate, wherein the mass percentage of MgCl2 is 40%, the mass percentage of KCl is 25%, the mass percentage of CaF2 is 15%, the mass percentage of NaCl is 15%, and the mass percentage of light magnesium carbonate is 5%.

[0122] (4) When the magnesium alloy reaches 730 °C and melts, it is die-cast to obtain magnesium products. The die-casting process parameters are: injection speed 5 m / s, vacuum degree 90 mbar, mold temperature 170 °C, injection pressure 90 MPa, and holding time 13 s.

[0123] Example 4

[0124] The weight percentage of each element in the die-cast magnesium product of this embodiment is as follows: 5% Al, 2% Ca, 4% Y, 0.25% Nd, 0.2% Mn; the total amount of other impurities is ≤0.1%, and the balance is Mg.

[0125] The preparation method of the die-cast magnesium product in this embodiment is as follows:

[0126] (1) Prepare materials according to the formula composition; among them, Mg and Al are prepared in the form of pure magnesium and pure aluminum, Mn is prepared in the form of Al-10Mn master alloy, Ca is prepared in the form of Mg-30Ca master alloy, Y is prepared in the form of Mg-30Y master alloy, and Nd is prepared in the form of Mg-10Nd master alloy.

[0127] (2) First, place pure magnesium in a melting furnace and introduce a mixture of N2 and SF6 gas (in which nitrogen accounts for 99.7% of the volume) and melt it at 740°C; then add pure aluminum, Al-10Mn master alloy, Mg-30Ca master alloy, Mg-30Y master alloy, and Mg-10Nd master alloy, and keep it at 740°C for 60 minutes. After melting, stir the molten metal evenly to obtain a mixed melt.

[0128] (3) Refining agent powder is added to the mixed melt at 730 °C for refining treatment and slag removal to obtain magnesium alloy; wherein the refining agent is a mixture of MgCl2, KCl, CaF2, NaCl and light magnesium carbonate, wherein the mass percentage of MgCl2 is 40%, the mass percentage of KCl is 25%, the mass percentage of CaF2 is 15%, the mass percentage of NaCl is 15%, and the mass percentage of light magnesium carbonate is 5%.

[0129] (4) The magnesium alloy is melted at 700 ℃ and die-cast to obtain magnesium products. The die-casting process parameters are: injection speed 5m / s, vacuum degree 90mbar, mold temperature 170℃, injection pressure 90MPa, and holding time 13s.

[0130] Example 5

[0131] The weight percentage of each element in the die-cast magnesium product of this embodiment is as follows: 4% Al, 3% Ca, 3% Y, 0.3% Nd, 0.3% Mn; the total amount of other impurities is ≤0.1%, and the balance is Mg.

[0132] The preparation method of the die-cast magnesium product in this embodiment is as follows:

[0133] (1) Prepare materials according to the formula composition; among them, Mg and Al are prepared in the form of pure magnesium and pure aluminum, Mn is prepared in the form of Al-10Mn master alloy, Ca is prepared in the form of Mg-30Ca master alloy, Y is prepared in the form of Mg-30Y master alloy, and Nd is prepared in the form of Mg-10Nd master alloy.

[0134] (2) First, place pure magnesium in a melting furnace and introduce a mixture of N2 and SF6 gas (in which nitrogen accounts for 99.7% of the volume) and melt it at 740°C; then add pure aluminum, Al-10Mn master alloy, Mg-30Ca master alloy, Mg-30Y master alloy and Mg-10Nd master alloy, and keep it at 740°C for 40 minutes. After melting, stir the molten metal evenly to obtain a mixed melt.

[0135] (3) Refining agent powder is added to the mixed melt at 720 °C for refining treatment and slag removal to obtain magnesium alloy; wherein the refining agent is a mixture of MgCl2, KCl, CaF2, NaCl and light magnesium carbonate, wherein the mass percentage of MgCl2 is 40%, the mass percentage of KCl is 25%, the mass percentage of CaF2 is 15%, the mass percentage of NaCl is 15%, and the mass percentage of light magnesium carbonate is 5%.

[0136] (4) The magnesium alloy is melted at 710 °C and die-cast to obtain magnesium products. The die-casting process parameters are: injection speed 5 m / s, vacuum degree 90 mbar, mold temperature 170 °C, injection pressure 90 MPa, and holding time 13 s.

[0137] Example 6

[0138] This embodiment provides a die-cast magnesium product and its preparation method, which is basically the same as the method in Embodiment 5, except that: the weight percentage of each element in the die-cast magnesium product of this embodiment is: 4% Al, 4% Ca, 4% Y, 0.3% Nd, 0.3% Mn; the total amount of other impurities is ≤0.1%, and the balance is Mg.

[0139] Example 7

[0140] This embodiment provides a die-cast magnesium product and its preparation method, which is basically the same as the method in Embodiment 5, except that the weight percentage of Nd element in this embodiment is 0.15%.

[0141] Example 8

[0142] This comparative example provides a die-cast magnesium product and its preparation method, which is basically the same as the method in Example 5, except that: the weight percentage of each element in the die-cast magnesium product of this example is: 4% Al, 1% Ca, 4% Y, 0.3% Nd, 0.3% Mn; the total amount of other impurities is ≤0.1%, and the balance is Mg.

[0143] Example 9

[0144] This comparative example provides a die-cast magnesium product and its preparation method, which is basically the same as the method in Example 5, except that: the weight percentage of each element in the die-cast magnesium product of this example is: 4% Al, 2% Ca, 1% Y, 0.3% Nd, 0.3% Mn; the total amount of other impurities is ≤0.1%, and the balance is Mg.

[0145] Example 10

[0146] This comparative example provides a die-cast magnesium product and its preparation method, which is basically the same as the method in Example 3, except that: the weight percentage of each element in the die-cast magnesium product of this example is: 4.7% Al, 4% Ca, 1% Y, 0.1% Nd, 0.1% Mn; the total amount of other impurities is ≤0.1%, and the balance is Mg.

[0147] Comparative Example 1

[0148] This comparative example is a conventional AM60 die-cast magnesium alloy, with the following weight percentages of each component: 6% Al, 0.3% Mn; total amount of other impurities ≤0.1%, balance being Mg.

[0149] In this comparative example, AM60 die-casting magnesium alloy was directly produced by melting commercial AM60 die-casting magnesium alloy ingots at 740 °C, followed by refining and slag removal at 730 °C. After the melt reached 710 °C, it was die-cast to obtain die-cast magnesium products (the refining process and die-casting process parameters were exactly the same as in Example 1).

[0150] Comparative Example 2

[0151] This comparative example provides a die-cast magnesium product and its preparation method, which is basically the same as the method in Example 1, except that Nd element is not added in this comparative example.

[0152] Comparative Example 3

[0153] This comparative example provides a die-cast magnesium product and its preparation method, which is basically the same as the method in Example 5, except that the weight percentage of Al element in this comparative example is 1%.

[0154] Comparative Example 4

[0155] This comparative example provides a die-cast magnesium product and its preparation method, which is basically the same as the method in Example 5, except that the weight percentage of Al element in this comparative example is 6%.

[0156] Comparative Example 5

[0157] This comparative example provides a die-cast magnesium product and its preparation method, which is basically the same as the method in Example 5, except that the weight percentage of Al element in this comparative example is 1.5%.

[0158] Test example:

[0159] Elemental analysis and quality testing of die-cast magnesium products: Testing was conducted according to GB / T 13748 "Chemical Analysis Methods for Magnesium and Magnesium Alloys", as detailed below:

[0160] First, 0.15g of magnesium shavings were scraped from the die-cast magnesium products obtained in each embodiment and comparative example. The magnesium shavings were added to a mixed solution of 3ml hydrochloric acid and 1ml sulfuric acid. After dissolving, pure water was added to prepare a 100ml solution. The solution was reacted and digested at room temperature to prepare the test solution. Then, the test solution was atomized at 20°C and sprayed into a high-temperature argon plasma to excite the element atoms. Finally, the content of each element was qualitatively and quantitatively determined based on the characteristic spectral intensity or mass-to-charge ratio.

[0161] Analysis of Al2Ca, Al2Y, and Al2Nd phases and phase particle size testing in die-cast magnesium products: SEM analysis was performed on the die-cast magnesium products obtained in each example and comparative example. Specifically, 20 different locations were selected for the samples of each example or comparative example to obtain 20 SEM images. Then, each phase in the SEM images was analyzed by SEM+EDS. The maximum particle size of each phase in the 20 SEM images was then analyzed and recorded as the particle size of that phase.

[0162] Salt spray corrosion test: The salt spray corrosion test was conducted according to GB / T 10125-2021 "Artificial Atmosphere Corrosion Test, Salt Spray Test". Specifically, the die-cast magnesium products obtained in each example and comparative example were cut into test samples with a test surface of 20mm×20mm. The test samples were placed in a salt spray test chamber, and the test chamber temperature was controlled at 35℃, the salt spray solution was 5% NaCl (the solvent of the salt spray solution was water, and the mass percentage of NaCl in the salt spray solution was 5%), and the spray deposition rate was 1.6ml / (h·80cm). 2 The test parameters, such as [list of parameters], were used to continuously conduct neutral salt spray corrosion. After 168 hours of testing, the sample was removed from the salt spray, the surface corrosion products were removed, and the sample was dried and weighed. The corrosion rate of the magnesium alloy was calculated in mm / year based on the mass loss of the sample before and after corrosion, the test duration, and the surface area of ​​the test surface.

[0163] Calculation formula:

[0164] Where Δm is the mass loss (g), and ρ is the density of the sample (g / cm³). 3 Here, ρ is taken as 1.78 g / cm³. 3 A is the surface area (cm²) of the test surface of the sample. 2 ), where t is the salt spray duration (in years).

[0165] Salt spray corrosion test of 304 stainless steel galvanic couple: The test was conducted according to GB / T 15748-2025 "Galvanic Corrosion Test Method for Marine Metal Materials". Specifically, magnesium products obtained in various examples and comparative examples were paired with stainless steel to form galvanic couples. Magnesium has a very negative electrode potential, while stainless steel has a more positive potential. Magnesium products, acting as the anode, will suffer severe accelerated galvanic corrosion. The samples were placed in simulated seawater (3.5wt% sodium chloride solution with a pH of about 7, where the solvent of the sodium chloride solution is water) and tested at (35±2)℃ for 15 days. After completing the galvanic corrosion test and removing the corrosion products from the sample surface, the corrosion rate K of the sample was determined. c Calculations were performed using the weightlessness method.

[0166] The standard uses the following calculation formula: K c = (W0-W1) / (S*t);

[0167] Where W0 is the mass of the sample before the test (g), W1 is the mass of the sample after the test (g) after removing corrosion products and drying, and S is the exposed surface area of ​​the anode plate (i.e., magnesium product) (m²). 2 ), where t is the experiment time (years).

[0168] The test results are shown in Tables 1-2.

[0169] Figure 1 The image shows a photograph of the die-cast magnesium product obtained in Example 1 of this invention after a salt spray corrosion test. Figure 2 This is a photograph of the die-cast magnesium product obtained in Comparative Example 1 of this invention after a salt spray corrosion test; Figure 3 This is a photograph of the die-cast magnesium product obtained in Comparative Example 2 of this invention after undergoing a salt spray corrosion test. From... Figures 1-3 As can be seen, after the salt spray corrosion test, the die-cast magnesium product obtained in Example 1 only produced a small amount of gray corrosion products on its surface. After the salt spray corrosion test, the die-cast magnesium product obtained in Comparative Example 2 produced more gray corrosion products on its surface, while the die-cast magnesium product obtained in Comparative Example 1 produced a large amount of black corrosion products on its surface.

[0170] Figure 4 This is a photograph of the die-cast magnesium product obtained in Example 1 of the present invention after a salt spray corrosion test by a 304 stainless steel galvanometer. Figure 5 This is a photograph of the die-cast magnesium product obtained in Comparative Example 1 of the present invention after a salt spray corrosion test by a 304 stainless steel galvanometer. Figure 6 This is a photograph of the die-cast magnesium product obtained in Comparative Example 2 of this invention after a salt spray corrosion test using a 304 stainless steel galvanometer. From... Figure 4-6 As can be seen from the results, after the die-cast magnesium product obtained in Example 1 was subjected to a salt spray corrosion test by a 304 stainless steel galvanometer, some corrosion pits and corrosion products were generated on the surface. After the die-cast magnesium product obtained in Comparative Example 2 was subjected to a salt spray corrosion test by a 304 stainless steel galvanometer, the surface corrosion area was more extensive and more corrosion products were generated. After the die-cast magnesium product obtained in Comparative Example 1 was subjected to a salt spray corrosion test by a 304 stainless steel galvanometer, a large amount of black corrosion products were generated on the surface, and the surface unevenness was significantly increased.

[0171] Figure 7 The image shows the SEM image of the die-cast magnesium product obtained in Example 1 of this invention. The red circle represents the Al2Ca phase, which is bright white and distributed in elongated or skeletal shapes along the grain boundaries. The yellow circle represents the Al2Y phase, which is white but darker than the Al2Ca phase and is distributed along the α-Mg phase, mostly at the grain boundaries. The green circle represents the Al2Nd phase, which is bright white, small, nearly circular or ellipsoidal, mainly distributed within the crystal lattice, with a small amount distributed at the grain boundaries.

[0172] Table 1

[0173]

[0174] Table 2

[0175]

[0176] Combining the data in Tables 1 and 2, it can be seen that the die-cast magnesium products obtained by this invention exhibit excellent salt spray corrosion resistance. The maximum salt spray corrosion rate of the die-cast magnesium products prepared in Examples 1-10 is only 0.54 mm / year, which is almost twice as fast as the commercial AM60 alloy in Comparative Example 1. The die-cast magnesium products obtained by this invention also exhibit excellent salt spray corrosion resistance of 304 stainless steel galvanometers. The maximum salt spray corrosion rate of the 304 stainless steel galvanometers of the die-cast magnesium products prepared in Examples 1-10 is 1.6 mm / year, which is more than twice as fast as the commercial AM60 alloy in Comparative Example 1.

[0177] Comparative Example 2 is a high corrosion-resistant, low galvanic die-cast magnesium product without the addition of Nd. Due to the absence of Nd to improve the electrode potential of the Mg matrix and the refinement effect on the microstructure, its salt spray corrosion resistance and galvanic corrosion resistance to salt spray are significantly lower than those of Example 1.

[0178] In Comparative Example 3, 0.70A+1.18D is 0.0105 and 0.50E+0.01G+0.07I is 0.0155, which does not meet the requirement that 0.70A+1.18D>0.50E+0.01G+0.07I, and its galvanometer's resistance to salt spray corrosion is significantly reduced.

[0179] In Comparative Example 4, the mass percentage of Al was 6%, which readily formed Mg. 17 Al 12 The corrosion resistance of this phase is significantly reduced.

[0180] In Comparative Example 5, 0.70A+1.18D is 0.0140 and 0.50E+0.01G+0.07I is 0.0155, which does not meet the requirement that 0.70A+1.18D>0.50E+0.01G+0.07I, and its galvanometer's resistance to salt spray corrosion is significantly reduced.

[0181] The above embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

Claims

1. A magnesium alloy, characterized in that, The magnesium alloy comprises the following components by mass percentage: 4-5% Al, 1-4% Ca, 1-4% Y, 0.1-0.3% Nd, 0.1-0.3% Mn, with the balance being unavoidable impurities and Mg. The magnesium alloy satisfies the following condition: 0.70A+1.18D>0.50E+0.01G+0.07I, where A is the mass percentage of Al in the magnesium alloy, D is the mass percentage of Mn in the magnesium alloy, E is the mass percentage of Ca in the magnesium alloy, G is the mass percentage of Y in the magnesium alloy, and I is the mass percentage of Nd in the magnesium alloy.

2. The magnesium alloy according to claim 1, characterized in that, The magnesium alloy satisfies the following condition: I > (E + G) / 35, where E is the mass percentage of Ca in the magnesium alloy, G is the mass percentage of Y in the magnesium alloy, and I is the mass percentage of Nd in the magnesium alloy.

3. The magnesium alloy according to claim 1 or 2, characterized in that, In the magnesium alloy, the mass percentage ratio of Ca to Y is 1:(1-3).

4. The magnesium alloy according to any one of claims 1-2, characterized in that, The magnesium alloy comprises Al2Ca phase, Al2Y phase and Al2Nd phase.

5. The magnesium alloy according to claim 4, characterized in that, The particle size of the Al2Ca phase is 3-20 μm; the particle size of the Al2Y phase is 5-15 μm.

6. The magnesium alloy according to claim 4, characterized in that, The particle size of the Al2Nd phase is 0.2-1 μm.

7. A method for preparing a magnesium alloy according to any one of claims 1-6, characterized in that, Includes the following steps: S1: In a protective atmosphere, raw materials including magnesium source, aluminum source, manganese source, calcium source, yttrium source and niobium source are melted and mixed to obtain a mixed melt; S2: The mixed melt is refined to obtain the magnesium alloy.

8. The method for preparing magnesium alloy according to claim 7, characterized in that, The specific steps of the refining process include: A refining agent is added to the mixed melt for refining treatment.

9. The method for preparing magnesium alloy according to claim 7, characterized in that, The specific steps for melting and mixing raw materials including magnesium, aluminum, manganese, calcium, yttrium, and niobium sources include the following: In a protective atmosphere, a magnesium source is first melted; then an aluminum source, a manganese source, a calcium source, a yttrium source, and a niobium source are added, kept at a constant temperature, and after melting, the molten metal is stirred evenly to obtain the mixed melt.

10. A magnesium product, characterized in that, The magnesium product is prepared from the magnesium alloy according to any one of claims 1-6.

11. The magnesium product according to claim 10, characterized in that, The salt spray corrosion rate of the magnesium product is 0.3-0.54 mm / year; the salt spray corrosion rate of the 304 stainless steel galvanometer of the magnesium product is 1.0-1.6 mm / year.

12. A method for preparing a magnesium product according to claim 10 or 11, characterized in that, include: The magnesium alloy is subjected to melting and die casting processes in sequence to obtain the magnesium product.

13. The preparation method according to claim 12, characterized in that, The melting temperature is 690-730℃.

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