High-strength high-electromagnetic-shielding magnesium alloy and preparation method thereof

Abstract

This invention belongs to the field of electromagnetic shielding alloy materials, specifically a high-strength, high-electromagnetic-shielding magnesium alloy and its preparation method. The magnesium alloy comprises the following components by mass percentage: Zn 3%–8%, RE 1%–6%, with the balance being magnesium and unavoidable impurities, totaling 100% by mass. RE refers to La and Ce light rare earth elements. During preparation, rapid solidification powder metallurgy and deformation processing are primarily used to achieve a balance and optimization of the electromagnetic shielding and mechanical properties of the Mg-Zn-RE alloy. The Mg-Zn-RE magnesium alloy prepared by this invention, through a combination of steps, exhibits excellent mechanical properties (yield strength ≥ 360 MPa) and outstanding electromagnetic shielding performance (dB ≥ 90), meeting the electromagnetic shielding effectiveness (SE) grading standard (excellent). It can be used in products requiring high precision and high sensitivity, as well as in aerospace, military, and other applications.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic shielding alloy materials, and specifically relates to a high-strength, high electromagnetic shielding Mg-Zn-RE alloy and its preparation method. RE refers to La and Ce light rare earth elements, and specifically to a high-strength, high electromagnetic shielding magnesium alloy and its preparation method. Background Technology

[0002] Advances in science and technology have propelled the rapid development of the electronics industry. While electronic devices bring convenience to people's lives and work, they also introduce a series of electromagnetic interference problems. In daily life, various radio and electronic devices radiate electromagnetic waves, affecting human health. In the aerospace field, aircraft and spacecraft need to be shielded from external electromagnetic interference to ensure the normal operation of precision electronic equipment. In the field of national defense and security, failure to effectively shield electromagnetic waves can easily lead to information leaks. Therefore, electromagnetic interference and its shielding are attracting the attention of researchers worldwide. Developing high-performance electromagnetic shielding materials and exploring their application as structural components in equipment are currently key research areas in the field of new materials.

[0003] Currently available electromagnetic shielding materials include: surface conductive shielding materials, whose main components are conductive particles such as gold, silver, copper, and nickel incorporated into polymers to create a blended conductive coating. These metals have the disadvantage of high density, but are low in cost, simple to produce, and easy to apply; and filled composite shielding materials, which have complex manufacturing processes, high costs, poor mechanical properties, and mediocre shielding effectiveness. Furthermore, electromagnetic shielding of equipment is generally achieved by adding an outer shell, requiring the shielding material to possess not only good electromagnetic shielding performance but also high strength. Therefore, developing lightweight materials that combine excellent mechanical properties and electromagnetic shielding performance is particularly important.

[0004] Encouragingly, magnesium alloys, as a green new energy material and the lightest metallic structural material of the 21st century, have been proven to possess good electromagnetic shielding performance, demonstrating excellent development potential and cost-effectiveness in electronic component applications. However, current magnesium alloys used for electromagnetic shielding, such as Mg-Al, Mg-Zn-Zr, Mg-Cu, and Mg-Sn alloys, all exhibit shortcomings in mechanical properties or require further improvement in electromagnetic shielding performance. Therefore, it is urgent to propose new methods to simultaneously improve the strength and electromagnetic shielding performance of magnesium alloys, meeting the current significant demand for high-strength, high-toughness, and lightweight electronic components, and successfully adapting to the expectations of the high-speed information age for electromagnetic shielding applications. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the prior art by providing a high-strength, high-electromagnetic-shielding magnesium alloy and its preparation method. This invention solves the problem of limited application of high-electromagnetic-shielding magnesium alloys due to their low mechanical properties and high cost. In the preparation method, rapid solidification powder metallurgy technology and deformation processing are used to achieve a balance and optimization of the electromagnetic shielding and mechanical properties of the Mg-Zn-RE alloy, resulting in a low-cost, high-electromagnetic-shielding, and high-strength Mg-Zn-RE alloy.

[0006] To achieve the above-mentioned objectives, the specific technical solution of the present invention is as follows: A high-strength, high-electromagnetic-shield Mg-Zn-RE alloy, wherein the mass percentage of each component is: Zn 3%~8% (specifically 3%, 4%, 5%, 6%, 7%, 8%, etc.), RE 1%~6% (specifically 1%, 2%, 3%, 4%, 5%, 6%, etc.), and the balance is magnesium and unavoidable impurities, and the total mass percentage is 100%.

[0007] Furthermore, in the aforementioned high-strength, high-electromagnetic-shield Mg-Zn-RE alloy, RE is at least one of La and Ce.

[0008] This application also protects a method for preparing a high-strength, high-electromagnetic-shield Mg-Zn-RE alloy as described above. During preparation, the electromagnetic shielding and mechanical properties of the Mg-Zn-RE alloy are optimized through rapid solidification powder metallurgy technology and deformation processing.

[0009] As a preferred embodiment of this application, a method for preparing a high-strength, high-electromagnetic-shield Mg-Zn-RE alloy specifically includes the following steps: 1) Drying and preheating: Weigh the raw materials according to the proportion, and then place the industrial pure magnesium, industrial pure zinc and Mg-RE master alloy in the drying oven for drying and preheating; 2) Melting and casting: The raw materials dried and preheated in step 1) are melted in a resistance melting furnace to obtain magnesium alloy melt; after the raw materials are completely melted, the temperature is lowered and the magnesium alloy melt is stirred thoroughly. After stirring, the melt is kept at a constant temperature, the slag on the surface of the melt is removed, and finally the melt is cast to obtain Mg-Zn-RE alloy ingot. 3) Rapid solidification preparation of alloy strip: The Mg-Zn-RE alloy ingot obtained in step 2) is melted, kept at a certain temperature, and then spun into strip to prepare Mg-Zn-RE alloy rapid solidification alloy strip. 4) Crushing and powdering, billet preparation: The Mg-Zn-RE alloy rapidly solidified alloy strip prepared in step 3) is crushed by a strip cutting machine to obtain alloy particles, and then the particles are pre-pressed to obtain pre-pressed alloy billets. 5) Deformation processing: The pre-pressed alloy billet obtained in step 4) is subjected to deformation processing to obtain the desired high-strength, high-electromagnetic shielding Mg-Zn-RE alloy rods or plates.

[0010] As a preferred embodiment of this application, in step 1) of the method for preparing a high-strength, high-electromagnetic-shield Mg-Zn-RE alloy, the drying temperature is 200-250℃ (specifically, it can be 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, etc.).

[0011] In a preferred embodiment of this application, in step 2) of the method for preparing a high-strength, high-electromagnetic-shield Mg-Zn-RE alloy, the melting temperature is 720~760℃ (specifically, 720℃, 730℃, 740℃, 750℃, 760℃, etc.); the temperature is then lowered to 700~720℃ (specifically, 700℃, 705℃, 710℃, 715℃, 720℃, etc.) for stirring; the temperature during stirring is lower than the temperature during melting. The temperature should be 200-250℃ (specifically, 2 minutes, 1 minute, 1.5 minutes, 2 minutes, etc.); the stirring time should be 1-2 minutes (specifically, 1 minute, 1.5 minutes, 2 minutes, etc.); the settling and heat preservation time should be 5-15 minutes (specifically, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes, 15 minutes, etc.); the temperature of the mold during casting should be 200-250℃ (specifically, 200℃, 210℃, 220℃, 230℃, 240℃, 250℃, etc.).

[0012] As a preferred embodiment of this application, in step 3) of the method for preparing a high-strength, high-electromagnetic-shield Mg-Zn-RE alloy, the Mg-Zn-RE alloy ingot is melted at a temperature of 720~760℃ (specifically, 720℃, 730℃, 740℃, 750℃, 760℃, etc.), and the holding time is 3~5min (specifically, 3min, 3.5min, 4min, 4.5min, 5min, etc.).

[0013] As a preferred embodiment of this application, in the preparation method of the high-strength, high-electromagnetic-shield Mg-Zn-RE alloy, both steps 2) and 3) require the introduction of CO2 protective gas.

[0014] As a preferred embodiment of this application, in step 4) of the method for preparing a high-strength, high-electromagnetic-shield Mg-Zn-RE alloy, the particle size of the alloy particles is 100-3000 μm (specifically, it can be 100 μm, 500 μm, 1000 μm, 1500 μm, 2000 μm, 2500 μm, 3000 μm, etc.).

[0015] In a preferred embodiment of this application, in step 5) of the method for preparing a high-strength, high-electromagnetic-shield Mg-Zn-RE alloy, the extrusion parameters are set as follows: extrusion temperature of 320-370℃ (specifically, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, etc.), extrusion ratio of 25:1, and extrusion speed of 10-20m / min (specifically, 10m / min, 12m / min, 14m / min, 16m / min, 18m / min, 20m / min, etc.).

[0016] A high-strength, high-electromagnetic-shielding Mg-Zn-RE alloy prepared by any of the above-described methods and steps, when tested with a 2mm thick standard sample, exhibits a tensile strength of 400MPa or higher, a yield strength of 360MPa or higher, and an elongation of ≥10%. Moreover, it demonstrates high and stable shielding effectiveness with minimal fluctuations across the entire 30~3000MHz bandwidth, achieving a performance of ≥90dB.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This application uses rapid solidification powder metallurgy technology to produce obvious solid solution strengthening, fine grain strengthening and dispersion strengthening effects, thereby improving and optimizing the microstructure and mechanical properties of magnesium alloys from multiple aspects.

[0018] (2) The present invention refines grains by using rapid solidification powder metallurgy technology and extrusion deformation technology. The grain size is reduced and the grain boundary area is increased. As an interface of impedance discontinuity, the grain boundary will increase the reflection of electromagnetic waves, thus significantly improving the shielding performance of the alloy.

[0019] (3) The Mg-Zn-RE magnesium alloy prepared by the present invention through a combination of steps has excellent mechanical properties (yield strength ≥360 MPa) and excellent electromagnetic shielding performance (dB≥90), meeting the electromagnetic shielding effectiveness (SE) grading standard (excellent). It can be used in products with high precision and high sensitivity requirements such as TEMPEST, aviation, aerospace, and military equipment, exceeding the limit of 47.4 dB specified in GB / T18387-2001 "Methods and Limits for Measurement of Magnetic Field Strength of Electric Vehicles", and fully meeting the electromagnetic radiation shielding requirements of electric vehicles. In addition, the raw materials are relatively inexpensive, the preparation process is simple, it is highly portable, easy to operate, easy to implement, and easy to industrialize. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the electromagnetic shielding performance of the magnesium alloys prepared in Examples 1, 2 and 3 of this application. Detailed Implementation

[0021] A high-strength, high-electromagnetic-shielding Mg-Zn-RE alloy, wherein the mass percentages of its components are: Zn 3%–8%, RE 1%–6%, with the balance being magnesium and unavoidable impurities.

[0022] A method for preparing a high-strength, high-electromagnetic-shield Mg-Zn-RE alloy is proposed, which achieves a balance and optimization of the electromagnetic shielding and mechanical properties of the Mg-Zn-RE alloy through rapid solidification powder metallurgy technology and deformation processing.

[0023] Specifically, the steps include the following: Mix the industrial pure magnesium, industrial pure zinc, and Mg-RE master alloy according to the mass percentage, and place them in an oven at 200-250°C for drying and preheating. The alloy is smelted in a resistance melting furnace with CO2 protective gas introduced. The temperature is maintained at 720-760°C while stirring to ensure complete melting of the raw materials. After complete melting, the temperature is lowered to 700-720°C, and the magnesium alloy melt is stirred thoroughly for 1-2 minutes. After stirring, the melt is allowed to stand for 5-15 minutes, then the surface slag is removed, and finally, it is cast to obtain the Mg-Zn-RE alloy ingot. Zn is added in the form of pure zinc, and RE (RE refers to La and Ce light rare earth elements; since La and Ce are in the same rare earth group, their atomic / electronic structures are very similar, and their mechanisms of action are highly consistent, showing almost no difference in magnesium alloys) is added in the form of a Mg-30wt%Ce master alloy. The casting mold temperature is 200-250°C.

[0024] Preparation of alloy strip using rapid solidification technology: The above alloy ingot is melted at 720~760℃ and held for 3~5 minutes, then Mg-Zn-RE alloy rapidly solidified alloy strip is prepared by spinning, during which CO2 protective gas is introduced.

[0025] Crushing and grinding: The above alloy strip is crushed by a strip cutting machine to prepare alloy particles of 100-3000um.

[0026] Ingot preparation: The above alloy powder is pre-pressed into alloy ingots.

[0027] Deformation processing: Alloy billets are then extruded to obtain bars or plates.

[0028] The extrusion parameters are set as follows: extrusion temperature 320-370℃, extrusion ratio 25:1, and extrusion speed 10-20m / min.

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, 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 pertains.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application. As used herein, the singular form includes the plural form unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this description, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0032] In this invention, some conventional operating equipment, devices and components have been omitted or only briefly described.

[0033] Unless otherwise specified in the examples, the conditions shall be performed according to the standard conditions or the conditions recommended by the manufacturer.

[0034] In this application, any percentage not marked indicates its weight percentage content.

[0035] Example 1: In this embodiment, the high-strength, high-electromagnetic-shield Mg-Zn-RE alloy is a Mg-Zn-Ce series magnesium alloy. By mass percentage, the Zn content is 6% and the Ce content is 3%, with the balance being magnesium and unavoidable impurities, and the total impurity content is ≤0.05%.

[0036] The preparation method of this Mg-Zn-Ce magnesium alloy specifically includes the following steps: The raw materials, industrial pure magnesium, industrial pure zinc, and Mg-Ce master alloy, are mixed according to a mass percentage and placed in an oven at 200°C for drying and preheating. The alloy is smelted in a resistance melting furnace under CO2 protective gas. The temperature is maintained at 760℃ with stirring to ensure complete melting of the raw materials. After complete melting, the temperature is lowered to 720℃, and the magnesium alloy melt is stirred thoroughly for 1 minute. After stirring, the melt is allowed to stand for 10 minutes, then the surface slag is removed, and finally, it is cast to obtain the Mg-Zn-Ce alloy ingot. Zn is added in the form of pure zinc, and Ce is added as a Mg-30wt%Ce master alloy. The casting mold temperature is 250℃.

[0037] Preparation of alloy strip using rapid solidification technology: The above alloy ingot is melted at 760°C and held for 3 minutes, and then Mg-Zn-Ce alloy rapidly solidified alloy strip is prepared by spinning, during which CO2 protective gas is introduced.

[0038] Crushing and grinding: The above alloy strip is crushed by a strip cutting machine to prepare alloy particles of 0.5-200 μm.

[0039] Ingot preparation: The above alloy powder is pre-pressed into alloy ingots.

[0040] Deformation processing: The alloy billet is then extruded to obtain a sheet, wherein the extrusion parameters are set as follows: extrusion temperature is 350℃, extrusion ratio is 25:1, and extrusion speed is 15m / min.

[0041] The obtained plate was prepared into an alloy test sample, denoted as Mg-6Zn-3Ce.

[0042] Example 2: In this embodiment, the high-strength, high-electromagnetic-shield Mg-Zn-RE alloy is a Mg-Zn-Ce series magnesium alloy; by mass percentage, the Zn content is 4%, the Ce content is 5%, and the balance is magnesium and unavoidable impurities, with a total impurity content ≤0.05%.

[0043] The preparation method of the Mg-Zn-Ce magnesium alloy in this embodiment is the same as that in Example 1.

[0044] The obtained plate was prepared into an alloy test sample, denoted as Mg-4Zn-5Ce.

[0045] Example 3: In this embodiment, the high-strength, high-electromagnetic-shield Mg-Zn-RE alloy is a Mg-Zn-Ce series magnesium alloy; by mass percentage, the Zn content is 6%, the Ce content is 5%, and the balance is magnesium and unavoidable impurities, with a total impurity content ≤ 0.05%.

[0046] The preparation method of the Mg-Zn-Ce magnesium alloy in this embodiment is the same as that in Example 1.

[0047] The obtained plate was prepared into an alloy test sample, denoted as Mg-6Zn-5Ce.

[0048] test: The Mg-Zn-Ce alloys prepared in Examples 1-3 and the alloys in Comparative Examples 1-3 were subjected to performance tests. The alloy in Comparative Example 1 was prepared according to Example 3 reported in CN 112159919 A, the alloy in Comparative Example 2 was prepared according to Example 2 reported in CN 102839307 A, and the alloy in Comparative Example 3 was prepared according to Example 2 reported in CN108165853 A.

[0049] In addition, the electromagnetic shielding performance was tested in accordance with GB / T 30142-2013, using a 2mm thick standard sample (test range 30~3000MHz); the mechanical properties refer to the tensile strength, yield strength and elongation of the alloy at room temperature, and the specific test results are shown in Table 1.

[0050] Table 1. Electromagnetic shielding and mechanical properties of the Mg-Zn-Ce alloys prepared in Examples 1-3 and the alloys in the comparative examples.

[0051] Analysis of Table 1 shows that the mechanical properties and electromagnetic shielding performance of the Mg-Zn-Ce alloy prepared by rapid solidification powder metallurgy technology and extrusion deformation have reached a very high level. The tensile strength of the obtained magnesium alloy can reach at least 375 MPa and above, the yield strength can reach at least 360 MPa and above, the elongation is ≥10%, and the shielding effectiveness is highly efficient and stable with very small fluctuation difference in the entire broadband range of 30~3000MHz, with a performance of ≥90dB. Compared with Example 3 (Comparative Example 1) reported in CN112159919 A, Example 2 (Comparative Example 2) reported in CN 102839307 A, and Example 2 (Comparative Example 3) reported in CN 108165853 A, the alloy prepared in this invention has greatly improved mechanical properties and excellent shielding performance across the entire wide frequency range of 30~3000MHz. This fully meets the requirements for material mechanical properties and electromagnetic shielding in applications such as daily life, national defense, medical facilities, and even cutting-edge high-precision instruments.

[0052] The embodiments described above merely illustrate specific implementation methods of this application, and while the descriptions are detailed and specific, they should not be construed as limiting the scope of protection of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the technical solution of this application, and these modifications and improvements all fall within the scope of protection of this application.

[0053] This background section is provided to generally present the context of the invention. The work of the currently named inventors, the work to the extent described in this background section, and aspects of this section that did not constitute prior art at the time of application are neither expressly nor impliedly acknowledged as prior art to the invention.

Claims

1. A high-strength, high-electromagnetic-shielding Mg-Zn-RE alloy, characterized in that, The mass percentages of each component are: Zn 3%~8%, RE 1%~6%, with the balance being magnesium and unavoidable impurities, and the total mass percentage is 100%.

2. The high-strength, high-electromagnetic-shielding Mg-Zn-RE alloy as described in claim 1, characterized in that: The RE is at least one of La and Ce.

3. The method for preparing a high-strength, high-electromagnetic-shield Mg-Zn-RE alloy as described in claim 2, characterized in that: During preparation, rapid solidification powder metallurgy technology and deformation processing are used to achieve a balance and optimization of the electromagnetic shielding and mechanical properties of Mg-Zn-RE alloys.

4. The preparation method of a high-strength, high-electromagnetic-shield Mg-Zn-RE alloy as described in claim 2, characterized in that... Specifically, the steps include the following: 1) Drying and preheating: Weigh the raw materials according to the proportion, and then place the industrial pure magnesium, industrial pure zinc and Mg-RE master alloy in the drying oven for drying and preheating; 2) Melting and casting: The raw materials dried and preheated in step 1) are melted in a resistance melting furnace to obtain magnesium alloy melt; After all the raw materials have melted, the temperature is lowered and the magnesium alloy melt is stirred thoroughly. After stirring, the melt is kept still and the surface slag is removed. Finally, it is cast to obtain Mg-Zn-RE alloy ingot. 3) Rapid solidification preparation of alloy strip: The Mg-Zn-RE alloy ingot obtained in step 2) is melted, kept at a certain temperature, and then spun into strip to prepare Mg-Zn-RE alloy rapid solidification alloy strip. 4) Crushing and powdering, billet preparation: The Mg-Zn-RE alloy rapidly solidified alloy strip prepared in step 3) is crushed by a strip cutting machine to obtain alloy particles, and then the particles are pre-pressed to obtain pre-pressed alloy billets. 5) Deformation processing: The pre-pressed alloy billet obtained in step 4) is extruded to obtain the required high-strength, high electromagnetic shielding Mg-Zn-RE alloy sheet.

5. The preparation method of a high-strength, high-electromagnetic-shield Mg-Zn-RE alloy as described in claim 4, characterized in that: The drying temperature in step 1) is 200-250℃.

6. The method for preparing a high-strength, high-electromagnetic-shield Mg-Zn-RE alloy as described in claim 4, characterized in that: In step 2), the melting temperature is 720~760℃; then the temperature is lowered to 700~720℃ for stirring; the stirring temperature is lower than the melting temperature; the stirring time is 1~2 minutes. The time for standing and keeping warm is 5 to 15 minutes; the temperature of the casting mold is 200 to 250℃.

7. The method for preparing a high-strength, high-electromagnetic-shield Mg-Zn-RE alloy as described in claim 4, characterized in that: In step 3), the Mg-Zn-RE alloy ingot is melted at a temperature of 720~760℃ and held for 3~5 minutes.

8. The method for preparing a high-strength, high-electromagnetic-shield Mg-Zn-RE alloy as described in claim 4, characterized in that: Both steps 2) and 3) require the introduction of CO2 protective gas.

9. The method for preparing a high-strength, high-electromagnetic-shield Mg-Zn-RE alloy as described in claim 4, characterized in that: In step 4), the particle size of the alloy particles is 100-3000 μm.

10. A high-strength, high-electromagnetic-shielding Mg-Zn-RE alloy prepared by the method according to any one of claims 3-9, characterized in that: When tested using a 2mm thick standard sample, the Mg-Zn-RE alloy exhibits a tensile strength of 400MPa or higher, a yield strength of 360MPa or higher, and an elongation of ≥10%. Moreover, it demonstrates high and stable shielding effectiveness with minimal fluctuations across the entire 30~3000MHz bandwidth, achieving a performance of ≥90dB.

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