Magnesium alloy with ultrahigh electromagnetic shielding effectiveness and excellent strength and preparation method thereof

Abstract

The invention discloses a magnesium alloy with ultrahigh electromagnetic shielding effectiveness and excellent strength and a preparation method thereof. According to the magnesium alloy, through specific component design (Gd, Zn and Zr), the working procedures of cast ingot casting, homogenization pretreatment, hot extrusion forming and aging treatment are combined, a double-peak grain structure is successfully constructed in the magnesium alloy, and a large number of fine beta'strengthening phases are induced and separated out; wherein the excellent strength and plasticity of the magnesium alloy are guaranteed through the double-peak grain structure; the strength of the material is remarkably improved through the fine beta'strengthening phase, and meanwhile, a formed interface network is beneficial to enhancing multiple times of reflection and absorption of electromagnetic waves, so that the strength is improved, the ultrahigh electromagnetic shielding effectiveness is guaranteed, the tensile strength of the material reaches and exceeds 370 MPa, and meanwhile, in the broadband range of 30 MHz to 3000 MHz, the electromagnetic shielding performance of the material is greatly improved. The electromagnetic shielding effectiveness stability is larger than 105 dB, breakthrough collaborative improvement of performance indexes is achieved, and the electromagnetic shielding material is suitable for being applied to the fields with extremely strict requirements for the weight, the structural reliability and the electromagnetic environment.

Description

Technical Field

[0001] This invention belongs to the field of magnesium alloy preparation technology, and relates to a magnesium alloy with both ultra-high electromagnetic shielding effectiveness and excellent strength, and its preparation method. Background Technology

[0002] With the rapid development of 5G mobile communication technology, the Internet of Things, artificial intelligence, and high-density integrated circuits, the operating frequency and integration of electronic devices are increasing daily, leading to increasingly serious electromagnetic interference and radiation problems. This not only affects the normal operation of precision instruments and information security but also poses a potential threat to human health. Therefore, the development of efficient and lightweight electromagnetic shielding materials has become an urgent need for the modern electronics industry. Magnesium alloys, as the lightest metallic structural material, are considered ideal candidate materials for the casings and internal shielding components of next-generation portable electronic devices due to their low density, high specific strength, excellent thermal and electrical conductivity, and good electromagnetic shielding potential.

[0003] However, the electromagnetic shielding effectiveness (especially absorption loss) of traditional magnesium alloys is often mutually restrictive to their mechanical strength. In existing technologies, traditional approaches to improving the electromagnetic shielding effectiveness of magnesium alloys mainly include: 1) adding highly conductive alloying elements (such as Cu and Ni) to increase overall conductivity, but these elements often lead to severe deterioration of the alloy's corrosion resistance or a significant increase in cost; 2) introducing a second phase or preparing composite materials, such as adding carbon nanotubes or graphene, but these external reinforcing phases are often difficult to disperse in the matrix and tend to agglomerate, not only worsening the alloy's formability but also introducing defects at the interface, impairing the alloy's mechanical properties, especially its plasticity.

[0004] On the other hand, the technology of improving the strength of magnesium alloys through conventional plastic deformation and heat treatment is relatively mature. Its core mechanism lies in grain refinement, introduction of dislocation strengthening, or age-induced precipitation strengthening. However, the resulting microstructure, such as uniform and fine equiaxed crystals and low-density or discontinuously distributed precipitates, while beneficial to strength, makes it difficult to construct a high-density, multi-scale electromagnetic wave scattering interface network within the alloy, resulting in the electromagnetic wave absorption and loss mechanism not being fully utilized. Therefore, magnesium alloys prepared by existing technologies often struggle to achieve an ideal synergy and balance between "ultra-high electromagnetic shielding effectiveness (especially in the high-frequency band)" and "excellent comprehensive mechanical properties." Summary of the Invention

[0005] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, the main objective of this invention is to provide a magnesium alloy that combines ultra-high electromagnetic shielding effectiveness with excellent strength, thereby addressing the problem of the mutual constraint between the electromagnetic shielding effectiveness and mechanical strength of existing magnesium alloys. The present invention also provides a method for preparing a magnesium alloy that has both ultra-high electromagnetic shielding effectiveness and excellent strength.

[0006] To achieve the above objectives, this invention develops a novel alloy design and preparation method, aiming to overcome the performance barriers of "shielding" and "strength" in magnesium alloys. By actively controlling and synergistically optimizing its microstructure (especially the synergistic design of precipitates and grain structure), a significant simultaneous improvement in electromagnetic shielding effectiveness and mechanical properties is achieved without relying on external reinforcing phases. This has significant scientific and engineering value for promoting the application of magnesium alloys in high-end electronic equipment. This invention is proposed based on this goal and is specifically achieved through the following technical solution: A magnesium alloy with both ultra-high electromagnetic shielding effectiveness and excellent strength comprises the following components by mass percentage: Gd: 8.49-13.55%, Zn: 0.85-1.23%, Zr: 0.41-0.73%, with the balance being Mg and unavoidable impurities, and the ratio of Gd / (Zn+Zr) is 7.1-8.9.

[0007] In some specific embodiments, the magnesium alloy comprises a bimodal grain structure and a nano-β' reinforcing phase, wherein the nano-β' reinforcing phase is uniformly distributed in the bimodal grain structure.

[0008] In some specific implementations, the bimodal grain structure is a mixed-crystal structure, with fine equiaxed grains having an average size of 3-4 μm and a fine grain ratio of 28-35%, and coarse deformed grains having an average size of 35-45 μm and a coarse grain ratio of 65-72%, and the nanoscale β' strengthening phase is uniformly distributed inside the fine equiaxed grains and the coarse deformed grains.

[0009] As part of the same inventive concept, this invention also provides a method for preparing the magnesium alloy with both ultra-high electromagnetic shielding effectiveness and excellent strength, comprising the following steps: 1) Ingot preparation: According to the formula requirements, the magnesium alloy raw materials are melted and cooled to obtain magnesium alloy ingots; 2) Ingot pretreatment: The magnesium alloy ingot is subjected to homogenization pretreatment to obtain pretreated ingot; 3) Sheet forming: The pretreated ingot is hot-extruded to obtain extruded sheet; 4) Inducing β' strengthening phase precipitation: The extruded sheet is subjected to aging precipitation treatment.

[0010] In some specific embodiments, the magnesium alloy comprises the following components by mass percentage: Gd: 8.49-13.55%, Zn: 0.85-1.23%, Zr: 0.41-0.73%, with the balance being Mg and unavoidable impurities.

[0011] In some specific embodiments, the melting process in step 1) is characterized by: stirring thoroughly at 740-750°C for 5-10 minutes under an inert atmosphere, then holding the mixture at that temperature for 20-25 minutes until the alloy melt cools to 640-660°C, and then circulating water is introduced for cooling.

[0012] In some specific embodiments, the homogenization pretreatment process conditions in step 2) are: holding at 505-510℃ for 17-19 hours.

[0013] In some specific embodiments, the ingot after heat preservation in step 2) is further cooled in hot water at 85-95°C.

[0014] In some specific embodiments, the process conditions for hot extrusion forming in step 3) are: extrusion temperature of 435-465℃, extrusion ratio of 14-18, and extrusion speed of 0.5-1.2m / min.

[0015] In some specific embodiments, the width of the extruded sheet obtained in step 3) is 50-55mm and the thickness is 6-8mm.

[0016] In some specific embodiments, the process conditions for the aging precipitation treatment in step 4) are: heat preservation at 195-205℃ for 46-50 hours followed by natural air cooling.

[0017] Compared with the prior art, the present invention has at least the following advantages: 1) The magnesium alloy provided by this invention combines ultra-high electromagnetic shielding effectiveness with excellent strength. Its tensile strength reaches and exceeds 370 MPa, and its shielding effectiveness is consistently greater than 105 dB in a wide frequency range of 30 MHz to 3000 MHz, achieving a breakthrough synergistic improvement in performance indicators. The material prepared by this magnesium alloy integrates lightweight, high strength, and wide-frequency ultra-high shielding, making it very suitable for applications with extremely demanding requirements for weight, structural reliability, and electromagnetic environment, such as aerospace vehicle cabins, shielding shells for high-end electronic equipment, and military equipment. It provides a new and high-performance material option for lightweighting and electromagnetic safety in these fields, and expands the application prospects of magnesium alloys in high-precision fields.

[0018] 2) The preparation method provided by this invention, through specific composition design (Gd, Zn, Zr), combined with ingot casting → homogenization pretreatment → hot extrusion forming → aging treatment, successfully constructs a bimodal grain structure and induces the precipitation of a large number of fine β' strengthening phases in magnesium alloys; the bimodal grain structure ensures the excellent strength and plasticity of magnesium alloys; the fine β' strengthening phases not only significantly improve the strength of the material (precipitation strengthening), but also the interface network formed by them is conducive to enhancing the multiple reflection and absorption of electromagnetic waves, thereby ensuring ultra-high electromagnetic shielding effectiveness while improving strength, solving the problem of mutual constraint between "strength" and "electromagnetic shielding effectiveness" in traditional magnesium alloys. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below.

[0020] Figure 1 Electromagnetic shielding effectiveness curves of the magnesium alloys prepared in Comparative Examples 1, 2 and Example 1 at room temperature; Figure 2 The engineering stress-strain curves of the magnesium alloys prepared in Comparative Examples 1, 2 and Example 1 at room temperature; Figure 3 Grain boundary diagrams of the magnesium alloys prepared in Comparative Examples 1, 2 and Example 1; Figure 4 Transmission electron microscopy images of the magnesium alloys prepared in Comparative Example 1 and Example 1. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The following embodiments are merely descriptive and not limiting, and should not be construed as limiting the scope of protection of the present invention.

[0022] When a quantity, concentration, or other value or parameter is described as a range, preferred range, or preferred upper and lower limits, it should be understood that it is equivalent to specifically disclosing any range by combining any pair of upper or preferred values ​​with any lower or preferred values, regardless of whether the range is specifically disclosed. Unless otherwise stated, the numerical range values ​​listed herein include the endpoints of the range and all integers and fractions within that range.

[0023] Unless otherwise stated, all percentages, parts, ratios, etc. in this document are by weight.

[0024] The materials, methods, and embodiments described herein are exemplary and should not be construed as limiting unless otherwise stated.

[0025] Example 1 This embodiment provides a method for preparing the magnesium alloy that combines ultra-high electromagnetic shielding effectiveness and excellent strength, comprising the following steps: Step 1: Ingot Preparation The formulation was designed with Gd: 13.1%, Zn: 1.2%, Zr: 0.6% by mass, and the ratio of Gd / (Zn+Zr) was 7.3, with the balance being Mg and unavoidable impurities. The raw materials, pure Mg, Mg-30Gd (wt%) master alloy, pure Zn, and Mg-30Zr (wt%) master alloy were placed in a steel crucible and heated to melt in an electric resistance furnace according to the aforementioned formulation requirements. A mixture of carbon dioxide and sulfur hexafluoride (volume ratio 99:1) was introduced as a protective gas. After complete melting, the mixture was stirred thoroughly at 745°C for 8 minutes, and then allowed to stand for 20 minutes. The steel crucible was then removed, and the alloy melt was allowed to cool to approximately 650°C. Circulating water was then introduced to cool the ingot to room temperature to obtain a magnesium alloy ingot. Step 2: Ingot Pretreatment Magnesium alloy ingots are held at 510℃ for 18 hours, then removed and cooled in hot water at 90℃ to obtain pretreated ingots. Step 3: Sheet forming The pretreated ingot was held at 450℃ for about 30 minutes, and then extruded into a sheet at an extrusion ratio of 16 and an extrusion rate of 0.9 m / min. The resulting extruded sheet had a cross-sectional area of ​​50 × 7 mm. 2 ; Step 4: Inducing β' strengthening phase precipitation After the extruded sheet is kept at 200℃ for 48 hours, it is naturally air-cooled to obtain a magnesium alloy that has both ultra-high electromagnetic shielding performance and excellent strength.

[0026] Example 2 This embodiment provides a method for preparing the magnesium alloy that combines ultra-high electromagnetic shielding effectiveness and excellent strength, comprising the following steps: Step 1: Ingot Preparation The formulation was designed with Gd: 13.4%, Zn: 1.1%, Zr: 0.5% by mass, and the ratio of Gd / (Zn+Zr) was 8.4, with the balance being Mg and unavoidable impurities. The raw materials, pure Mg, Mg-30Gd (wt%) master alloy, pure Zn, and Mg-30Zr (wt%) master alloy were placed in a steel crucible and heated to melt in an electric resistance furnace according to the aforementioned formulation requirements. A mixture of carbon dioxide and sulfur hexafluoride (volume ratio 99:1) was introduced as a protective gas. After complete melting, the mixture was stirred thoroughly at 745°C for 8 minutes, and then allowed to stand for 20 minutes. The steel crucible was then removed, and the alloy melt was allowed to cool to approximately 650°C. Circulating water was then introduced to cool the ingot to room temperature to obtain a magnesium alloy ingot. Step 2: Ingot Pretreatment Magnesium alloy ingots were held at 505℃ for 19 hours, and then removed and cooled in hot water at 85℃ to obtain pretreated ingots. Step 3: Sheet forming The pretreated ingot was held at 435℃ for 30 minutes, and then extruded into a sheet at an extrusion ratio of 14 and an extrusion rate of 0.5 m / min. The resulting extruded sheet had a cross-sectional area of ​​50 × 7 mm. 2 ; Step 4: Inducing β' strengthening phase precipitation After the extruded sheet is kept at 195℃ for 50 hours, it is naturally air-cooled to obtain a magnesium alloy that has both ultra-high electromagnetic shielding effectiveness and excellent strength.

[0027] Example 3 This embodiment provides a method for preparing the magnesium alloy that combines ultra-high electromagnetic shielding effectiveness and excellent strength, comprising the following steps: Step 1: Ingot Preparation The formulation was designed with Gd: 13.2%, Zn: 1.1%, Zr: 0.6% by mass, and the ratio of Gd / (Zn+Zr) was 7.8, with the balance being Mg and unavoidable impurities. The raw materials, pure Mg, Mg-30Gd (wt%) master alloy, pure Zn, and Mg-30Zr (wt%) master alloy were placed in a steel crucible and heated to melt in an electric resistance furnace according to the aforementioned formulation requirements. A mixture of carbon dioxide and sulfur hexafluoride (volume ratio 99:1) was introduced as a protective gas. After complete melting, the mixture was stirred thoroughly at 745°C for 8 minutes, and then allowed to stand for 20 minutes. The steel crucible was then removed, and the alloy melt was allowed to cool to approximately 650°C. Circulating water was then introduced to cool the ingot to room temperature to obtain a magnesium alloy ingot. Step 2: Ingot Pretreatment Magnesium alloy ingots were held at 510℃ for 17 hours, and then removed and cooled in hot water at 95℃ to obtain pretreated ingots. Step 3: Sheet forming The pretreated ingot was held at 465℃ for about 30 minutes, and then extruded into a sheet at an extrusion ratio of 18 and an extrusion rate of 1.2 m / min. The resulting extruded sheet had a cross-sectional area of ​​50 × 7 mm. 2 ; Step 4: Inducing β' strengthening phase precipitation After the extruded sheet is kept at 205℃ for 46 hours, it is naturally air-cooled to obtain a magnesium alloy that has both ultra-high electromagnetic shielding performance and excellent strength.

[0028] Comparative Example 1 This comparative example provides a method for preparing a magnesium alloy, which is basically the same as that in Example 1, except that the proportions of each raw material in the prepared magnesium alloy ingot are different. Specifically, by mass percentage, the proportions are Gd: 8.8%, Zn: 1.2%, Zr: 0.7%, and the ratio of Gd / (Zn+Zr) is 4.6, with the balance being Mg and unavoidable impurities; the process steps and parameters are the same as those in Example 1.

[0029] Comparative Example 2 This comparative example provides a method for preparing a magnesium alloy, which is basically the same as that in Example 1, except that step four is omitted, that is, the extruded sheet is not kept at 195°C for 50 hours and then naturally cooled to induce the precipitation of β' strengthening phase.

[0030] Performance testing Electromagnetic shielding effectiveness and room temperature mechanical properties were tested on the magnesium alloy plates prepared in Comparative Examples 1, 2 and Example 1. The electromagnetic shielding effectiveness curves are shown below. Figure 1 As shown, the engineering stress-strain curve is as follows: Figure 2 As shown in Table 1, the specific electromagnetic shielding effectiveness and mechanical properties of the magnesium alloy plates prepared in Comparative Examples 1, 2 and Example 1 are shown in Table 1.

[0031] Table 1 Electromagnetic shielding effectiveness and mechanical properties of magnesium alloys prepared in Comparative Examples 1, 2 and Example 1 Table 1 shows that aging treatment significantly improved the yield strength of the magnesium alloy. In Example 3, the tensile strength and yield strength of the magnesium alloy increased by 99 MPa and 121 MPa respectively compared to Comparative Example 1, while the elongation at break only decreased slightly. The electromagnetic shielding effectiveness of Example 1 was consistently higher than that of Comparative Examples 1 and 2 in the frequency range of 30-3000 MHz. Generally, the electromagnetic shielding effectiveness of an alloy decreases monotonically with increasing frequency. In this application, the electromagnetic shielding effectiveness of Comparative Example 1 in the frequency range of 30-3000 MHz exhibited a unique segmented (stage 1: 30-1000 MHz, stage 2: 1000-2000 MHz, stage 3: 2000-3000 MHz) attenuation behavior (e.g., ...). Figure 1(As shown in the figure) By increasing the Gd content and aging treatment, the segmented attenuation behavior of this electromagnetic shielding effectiveness was effectively mitigated, and its effect was mainly concentrated in the low-frequency stage of segmented attenuation (stage 1). Except for Comparative Examples 1 and 2, Example 1 almost overcame the attenuation of electromagnetic shielding effectiveness in the low-frequency stage. In particular, Example 1 showed almost no attenuation of electromagnetic shielding effectiveness in stage 1; at the same time, the attenuation behavior of electromagnetic shielding effectiveness in stages 2 and 3 of Example 1 was also delayed; this enabled Example 1 to have ultra-high electromagnetic shielding effectiveness in the frequency range of 30-3000 MHz; therefore, Example 1 achieved the optimal combination of strength and electromagnetic shielding effectiveness, with a tensile strength of 372±6 MPa and an electromagnetic shielding effectiveness of 106-118 dB in the 30-3000 MHz range.

[0032] Figure 3 Grain boundary diagrams for Comparative Examples 1, 2 and Example 1; Figure 4 Transmission electron microscopy images of the magnesium alloys prepared in Comparative Example 1 and Example 1, from... Figure 3 and Figure 4 It can be seen that Comparative Example 1 underwent complete dynamic recrystallization during extrusion, resulting in a uniform equiaxed grain structure with an average grain size of 9.6 μm. Comparative Example 2 underwent partial dynamic recrystallization during extrusion, exhibiting a bimodal grain structure. The average size of the fine equiaxed grains was 3.6 μm, accounting for 31% of the total. The average size of the coarse deformed grains was 39 μm, accounting for 69% of the total. Example 1, compared to Comparative Example 2, included an additional aging precipitation treatment. Since the grain structure does not change during the aging precipitation treatment, the grain structure of Example 1 is essentially the same as that of Comparative Example 2. Compared to Comparative Example 1, the bimodal grain structure exhibited in Comparative Example 2 and Example 1 can generate additional heterogeneous deformation-induced strengthening, achieving improved strength while maintaining good plasticity.

[0033] Electromagnetic shielding effectiveness mainly depends on a material's ability to reflect and absorb electromagnetic waves. For non-ferromagnetic metals such as magnesium alloys, their internal microstructure, especially the distribution characteristics of precipitates and the morphology of grain structure, jointly determines the propagation and dissipation behavior of electromagnetic waves in the material. Figure 3 and Figure 4 This indicates that the magnesium alloy in Comparative Example 1 has an equiaxed crystal structure and a small amount of unevenly distributed β' strengthening phase. The grain boundary density of equiaxed crystals is relatively low, and the number of precipitated phases is small and unevenly distributed. This results in a limited number of interfaces (phase boundaries, grain boundaries) inside the material that can effectively scatter electromagnetic waves. Therefore, electromagnetic waves are mainly reflected at the surface of the material, and the proportion of absorption and attenuation after entering the interior is low. The overall shielding effectiveness, especially the absorption loss, is limited.

[0034] In contrast, Example 1 exhibits a significantly optimized microstructure: on the one hand, it contains a large number of uniformly distributed β' reinforcing phases. These high-density nanoprecipitates form extremely rich phase interfaces in the matrix, becoming strong scattering centers for electromagnetic waves and greatly enhancing the multiple reflections and absorption loss paths of electromagnetic waves within the material. On the other hand, its unique bimodal grain structure further introduces a multi-scale grain boundary distribution. The interface between large and small grains has higher curvature and orientation difference, which can effectively scatter electromagnetic waves of different wavelengths and broaden the effective shielding bandwidth.

[0035] Most importantly, these two microstructural features produce a good synergistic effect. The high-density, uniform β' strengthening phase mainly enhances wave scattering at the microscale, while the bimodal grain structure provides additional scattering interfaces at the mesoscale. Together, they construct a multi-layered, multi-scale internal multi-interface network. When electromagnetic waves enter the material, they are repeatedly scattered, refracted, and absorbed by this dense network, greatly extending the propagation path and efficiently dissipating energy, thereby significantly improving the overall electromagnetic shielding effectiveness, especially its contribution to the absorption mechanism.

[0036] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention.

Claims

1. A magnesium alloy possessing both ultra-high electromagnetic shielding effectiveness and excellent strength, characterized in that, It comprises the following components by mass percentage: Gd: 8.49-13.55%, Zn: 0.85-1.23%, Zr: 0.41-0.73%, with the balance being Mg and unavoidable impurities.

2. The magnesium alloy with both ultra-high electromagnetic shielding effectiveness and excellent strength according to claim 1, characterized in that, The magnesium alloy comprises a bimodal grain structure and a nano-β' reinforcing phase, wherein the nano-β' reinforcing phase is uniformly distributed in the bimodal grain structure.

3. The magnesium alloy with both ultra-high electromagnetic shielding effectiveness and excellent strength according to claim 2, characterized in that, The bimodal grain structure is a mixed-crystal structure, with fine equiaxed grains having an average size of 3-4 μm and a fine grain ratio of 28-35%, and coarse deformed grains having an average size of 35-45 μm and a coarse grain ratio of 65-72%. The nanoscale β' strengthening phase is uniformly distributed inside the fine equiaxed grains and the coarse deformed grains.

4. A method for preparing a magnesium alloy possessing both ultra-high electromagnetic shielding effectiveness and excellent strength according to any one of claims 1-3, characterized in that, Includes the following steps: 1) Ingot preparation: According to the formula requirements, the magnesium alloy raw materials are melted and cooled to obtain magnesium alloy ingots; 2) Ingot pretreatment: The magnesium alloy ingot is subjected to homogenization pretreatment to obtain a pretreated ingot; 3) Sheet forming: The pretreated ingot is hot-extruded to obtain extruded sheet; 4) Inducing β' strengthening phase precipitation: The extruded sheet is subjected to aging precipitation treatment.

5. The method for preparing a magnesium alloy with both ultra-high electromagnetic shielding effectiveness and excellent strength according to claim 4, characterized in that, The magnesium alloy comprises the following components by mass percentage: Gd: 8.49-13.55%, Zn: 0.85-1.23%, Zr: 0.41-0.73%, with the balance being Mg and unavoidable impurities, and the ratio of Gd / (Zn+Zr) is 7.1-8.

9.

6. The method for preparing a magnesium alloy with both ultra-high electromagnetic shielding effectiveness and excellent strength according to claim 4, characterized in that, The melting process described in step 1) is as follows: under an inert atmosphere, stir thoroughly at 740-750℃ for 5-10 minutes, then let stand and keep warm for 20-25 minutes. When the alloy melt cools to 640-660℃, circulate water to cool it.

7. The method for preparing a magnesium alloy with both ultra-high electromagnetic shielding effectiveness and excellent strength according to claim 4, characterized in that, The homogenization pretreatment process conditions in step 2) are: heat treatment at 505-510℃ for 17-19 hours.

8. The method for preparing a magnesium alloy with both ultra-high electromagnetic shielding effectiveness and excellent strength according to claim 7, characterized in that, It also includes cooling the ingot after heat preservation as described in step 2) in hot water at 85-95°C.

9. The method for preparing a magnesium alloy with both ultra-high electromagnetic shielding effectiveness and excellent strength according to claim 4, characterized in that, The hot extrusion forming process conditions in step 3) are: extrusion temperature of 435-465℃, extrusion ratio of 14-18, and extrusion speed of 0.5-1.2m / min.

10. The method for preparing a magnesium alloy with both ultra-high electromagnetic shielding effectiveness and excellent strength according to claim 5, characterized in that, The process conditions for the aging precipitation treatment described in step 4) are: heat preservation at 195-205℃ for 46-50 hours followed by natural air cooling.

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