Low-alloying rare earth magnesium alloy with high strength and high electromagnetic shielding performance and preparation method of low-alloying rare earth magnesium alloy

Abstract

The invention provides a low-alloying rare earth magnesium alloy with high strength and high electromagnetic shielding performance and a preparation method of the low-alloying rare earth magnesium alloy, and belongs to the technical field of magnesium alloys. The invention provides a low-alloying rare earth magnesium alloy with high strength and high electromagnetic shielding performance, which comprises the following chemical components in percentage by mass: 0.5 to 1.5 percent of Sm, 0.3 to 0.7 percent of Zn, 0.4 to 0.6 percent of Zr, 0.2 to 0.6 percent of Mn and the balance of Mg. According to the invention, trace Zr and Mn elements are compositely added, a banded structure distributed along the ED direction can be formed after extrusion, the structure and a matrix just form a sandwich-like structure, and incident electromagnetic waves can be reflected and absorbed for multiple times, so that a good electromagnetic shielding effect is achieved; a trace amount of Zr and Mn elements are compositely added, so that the grain size of the alloy is obviously refined, a very good refined grain strengthening effect is achieved, and the strength and the electromagnetic shielding performance of the rare earth magnesium alloy are improved.

Description

Technical Field

[0001] This invention belongs to the field of magnesium alloy technology, specifically relating to a low-alloy rare-earth magnesium alloy with both high strength and high electromagnetic shielding performance and its preparation method. Background Technology

[0002] Magnesium alloys, as the lightest metallic structural materials, exhibit enormous application potential in aerospace, portable electronic devices, and communications due to their high specific strength, excellent casting properties, and good electromagnetic shielding performance. In particular, with the rapid development of 5G communication and IoT technologies, the requirements for lightweight and electromagnetic compatibility in electronic devices are becoming increasingly stringent. Developing magnesium alloys that combine high strength with high electromagnetic shielding performance has become one of the research hotspots in the materials science field.

[0003] However, pure magnesium has poor mechanical properties and cannot be used directly as structural components. It is typically strengthened through alloying. Currently widely used commercial magnesium alloys, such as the AZ91 (Mg-Al-Zn) and AM60 (Mg-Al-Mn) series, while possessing good casting properties, still lack the absolute strength required for high-end structural components. More importantly, the electromagnetic shielding effectiveness (EMI SE) of these alloys is typically only at the 50-60 dB level, making it difficult to cope with increasingly severe electromagnetic interference environments.

[0004] To further enhance the strength of magnesium alloys, researchers have introduced rare earth (RE) elements. Rare earth elements such as samarium (Sm), gadolinium (Gd), and yttrium (Y) can produce significant solid solution strengthening and precipitation strengthening effects, leading to the development of a series of high-performance rare earth magnesium alloys. For example, Mg-Sm-Zn alloys can effectively improve their strength by generating a stable Mg-Sm phase, but this still cannot improve their electromagnetic shielding performance.

[0005] Therefore, how to improve rare earth magnesium alloys to achieve both high strength and high electromagnetic shielding performance has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a low-alloy rare-earth magnesium alloy with both high strength and high electromagnetic shielding performance, and a method for preparing the same. The low-alloy rare-earth magnesium alloy provided by this invention possesses both high strength and high electromagnetic shielding performance.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a low-alloy rare-earth magnesium alloy with both high strength and high electromagnetic shielding performance, comprising the following chemical composition by mass percentage: Sm 0.5~1.5%, Zn 0.3~0.7%, Zr 0.4~0.6%, Mn 0.2~0.6% and the balance Mg.

[0008] Preferably, by mass percentage, it comprises the following chemical components: Sm 0.8~1.2%, Zn 0.4~0.6%, Zr 0.5~0.6%, Mn 0.5~0.6%, and the balance Mg.

[0009] Preferably, the chemical composition, by mass percentage, includes the following: Sm 1.0%, Zn 0.5%, Zr 0.6%, Mn 0.6%, and the balance Mg.

[0010] This invention also provides a method for preparing the low-alloyed rare-earth magnesium alloy with both high strength and high electromagnetic shielding performance as described in the above technical solution, comprising the following steps: (1) The alloy raw materials are melted and cast in sequence to obtain ingots; (2) The ingots obtained in step (1) are subjected to homogenization treatment and hot extrusion in sequence to obtain a low-alloy rare earth magnesium alloy with both high strength and high electromagnetic shielding performance.

[0011] Preferably, the melting in step (1) is vacuum melting.

[0012] Preferably, the heat preservation temperature for homogenization treatment in step (2) is 380~420℃, and the heat preservation time for homogenization treatment is 4~8h.

[0013] Preferably, step (2) further includes preheating the billet before hot extrusion; the preheating temperature is 430~470℃ and the preheating time is 1~2h.

[0014] Preferably, step (2) further includes preheating the mold before hot extrusion; the preheating temperature is 350~400℃ and the preheating time is ≥1h.

[0015] Preferably, the temperature of hot extrusion in step (2) is 400~500℃ and the speed of hot extrusion is 0.5~2mm / s.

[0016] Preferably, the extrusion ratio of hot extrusion in step (2) is (15~30):1.

[0017] This invention provides a low-alloy rare-earth magnesium alloy with both high strength and high electromagnetic shielding performance. By mass percentage, it comprises the following chemical composition: Sm 0.5~1.5%, Zn 0.3~0.7%, Zr 0.4~0.6%, Mn 0.2~0.6%, and the balance Mg. The addition of trace amounts of Zr and Mn elements in this invention results in a banded structure distributed along the ED direction after extrusion. This structure, together with the matrix, forms a sandwich-like structure, effectively reflecting and absorbing incident electromagnetic waves multiple times, thus achieving excellent electromagnetic shielding. The addition of trace amounts of Zr and Mn elements significantly refines the grain size of the alloy, resulting in excellent grain refinement and strengthening, thereby improving the strength and electromagnetic shielding performance of the rare-earth magnesium alloy. The results of the embodiments show that the low-alloy rare-earth magnesium alloy provided by this invention has a tensile strength of 361.6 MPa, a yield strength of 350.1 MPa, and a significantly improved electromagnetic shielding performance. Attached Figure Description

[0018] Figure 1 SEM image of the low-alloyed rare-earth magnesium alloy prepared in Example 1; Figure 2 The image shows the IPF (Integrated Part Formation) of the low-alloyed rare-earth magnesium alloy prepared in Example 1. Figure 3 This is a statistical diagram of the grain size of the low-alloyed rare-earth magnesium alloy prepared in Example 1; Figure 4 The IPF diagram of the rare earth magnesium alloy prepared in Comparative Example 1 is shown. Figure 5 A statistical chart of grain size of the rare earth magnesium alloy prepared in Comparative Example 1; Figure 6 The tensile strength and yield strength of the low-alloyed rare earth magnesium alloy prepared in Example 1 and the rare earth magnesium alloy prepared in Comparative Example 1 are compared. Figure 7 This is a comparison chart of the electromagnetic shielding effectiveness of the low-alloy rare-earth magnesium alloy prepared in Example 1 and the rare-earth magnesium alloy prepared in Comparative Example 1. Detailed Implementation

[0019] This invention provides a low-alloy rare-earth magnesium alloy with both high strength and high electromagnetic shielding performance, comprising the following chemical composition by mass percentage: Sm 0.5~1.5%, Zn 0.3~0.7%, Zr 0.4~0.6%, Mn 0.2~0.6% and the balance Mg.

[0020] The chemical composition of the low-alloyed rare-earth magnesium alloy with high strength and high electromagnetic shielding performance provided by the present invention includes 0.5-1.5% Sm by mass percentage. As one embodiment, the mass percentage of Sm can be 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, or 1.4%.

[0021] The chemical composition of the low-alloy rare-earth magnesium alloy with high strength and high electromagnetic shielding performance provided by the present invention includes 0.3-0.7% Zn by mass percentage. As one embodiment, the mass percentage of Zn can be 0.4%, 0.5%, or 0.6%.

[0022] The chemical composition of the low-alloy rare-earth magnesium alloy with high strength and high electromagnetic shielding performance provided by the present invention includes 0.4-0.6% Zr by mass percentage. As one embodiment, the mass percentage of Zr can be 0.45%, 0.5%, or 0.55%. In the present invention, the Zr can improve the electromagnetic shielding performance and strength of the magnesium alloy.

[0023] The chemical composition of the low-alloy rare-earth magnesium alloy with high strength and high electromagnetic shielding performance provided by this invention, by mass percentage, includes 0.2-0.6% Mn. As one embodiment, the mass percentage of Mn can be 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, or 0.55%. In this invention, the Mn can improve the electromagnetic shielding performance and strength of the magnesium alloy.

[0024] The chemical composition of the low-alloy rare-earth magnesium alloy with high strength and high electromagnetic shielding performance provided by this invention, by weight percentage, includes the balance Mg. In this invention, Mg is a matrix element.

[0025] This invention incorporates trace amounts of Zr and Mn elements, which, upon extrusion, form a banded structure distributed along the ED direction. This structure, together with the matrix, forms a sandwich-like structure that effectively reflects and absorbs incident electromagnetic waves multiple times, thus providing excellent electromagnetic shielding. The addition of trace amounts of Zr and Mn elements significantly refines the grain size of the alloy, resulting in excellent grain refinement and strengthening, thereby improving the strength and electromagnetic shielding performance of the rare earth magnesium alloy.

[0026] This invention also provides a method for preparing the low-alloyed rare-earth magnesium alloy with both high strength and high electromagnetic shielding performance as described in the above technical solution, comprising the following steps: (1) The alloy raw materials are melted and cast in sequence to obtain ingots; (2) The ingots obtained in step (1) are subjected to homogenization treatment and hot extrusion in sequence to obtain a low-alloy rare earth magnesium alloy with both high strength and high electromagnetic shielding performance.

[0027] This invention involves sequentially melting and casting alloy raw materials to obtain ingots.

[0028] The present invention does not have any special limitation on the source of the alloy raw materials, and commercially available products known to those skilled in the art can be used.

[0029] In this invention, the melting is preferably performed under vacuum. This invention does not impose any particular limitation on the specific vacuum melting operation; any operation well-known to those skilled in the art can be used.

[0030] The present invention does not impose any special limitations on the casting operation; any operation known to those skilled in the art can be used.

[0031] After obtaining the ingot, the present invention performs homogenization treatment and hot extrusion on the ingot in sequence to obtain a low-alloy rare earth magnesium alloy with both high strength and high electromagnetic shielding performance.

[0032] In this invention, it is preferable to remove surface oxide scale and defects before homogenizing the ingot.

[0033] The present invention does not have any special limitations on the operation of removing oxide scale and defects, and any operation known to those skilled in the art can be used.

[0034] In this invention, the homogenization process is preferably carried out in a box-type resistance furnace. This invention does not specify a particular model of box-type resistance furnace; any instrument or equipment well-known to those skilled in the art can be used.

[0035] In this invention, the holding temperature for homogenization treatment is preferably 380~420℃, more preferably 400℃; the holding time for homogenization treatment is preferably 4~8h, more preferably 6h. By limiting the process parameters of homogenization treatment within the above range, this invention can effectively eliminate dendrite segregation and ensure uniform distribution of solute atoms.

[0036] In this invention, the preferred cooling method for the homogenization process is furnace-side cooling. This invention does not impose any particular limitations on the furnace-side cooling operation; any operation well-known to those skilled in the art can be used to cool the furnace to room temperature.

[0037] After the homogenization process is completed, the present invention preferably processes the ingot obtained by the homogenization process to obtain a billet, and then coats the surface of the billet with a lubricant.

[0038] The present invention does not impose any special limitations on the processing operation; adjustments can be made according to actual needs.

[0039] This invention does not specify the particular type of lubricant; any lubricant well-known to those skilled in the art can be used. Coating the surface of the blank with a lubricant in this invention can reduce friction and heat loss during the extrusion process.

[0040] The present invention does not impose any special limitations on the operation of applying the lubricant; any operation known to those skilled in the art can be used.

[0041] In this invention, the hot extrusion process preferably includes preheating the billet; the preheating temperature is preferably 430~470℃, more preferably 450℃; and the preheating time is preferably 1~2h.

[0042] In this invention, the process of hot extrusion preferably includes preheating the mold; the preheating temperature is preferably 350~400℃; and the preheating time is preferably ≥1h. As one embodiment, the preheating temperature can be 360℃, 370℃, 380℃, or 390℃.

[0043] In this invention, the hot extrusion is preferably carried out in an extruder. This invention does not specify a particular type of extruder; any instrument or equipment well-known to those skilled in the art can be used.

[0044] In this invention, the hot extrusion temperature is preferably 400~500℃, more preferably 450℃; the hot extrusion speed is preferably 0.5~2mm / s, more preferably 1mm / s; and the hot extrusion ratio is preferably (15~30):1. As one embodiment, the hot extrusion ratio can be 16:1, 17:1, 18:1, 19:1, 20:1, 21:1, 22:1, 23:1, 24:1, 25:1, 26:1, 27:1, 28:1, or 29:1.

[0045] After hot extrusion, the present invention preferably cools and processes the hot-extruded product in sequence to obtain a low-alloyed rare earth magnesium alloy with both high strength and high electromagnetic shielding performance.

[0046] In this invention, the cooling is preferably air cooling. This invention does not impose any particular limitations on the operation of the air cooling; any operation well-known to those skilled in the art, such as natural cooling to room temperature in air, is acceptable.

[0047] The present invention does not have any special limitations on the processing operation; it is sufficient to remove the unstable deformed parts at the head and tail.

[0048] The low-alloy rare-earth magnesium alloy prepared by this invention has a smooth surface and a dense structure.

[0049] The core advantage of this invention (high strength and high shielding) mainly stems from the innovative composition design of "Zr / Mn composite addition". Through synergy with the optimized process of "homogenization + hot extrusion", the conductivity of the material is optimized and a large number of effective internal interfaces are created under the premise of low alloying, thereby achieving a breakthrough in performance.

[0050] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0051] Example 1 (Mg-1Sm-0.5Zn-0.6(Zr,Mn)) The low-alloy rare earth magnesium alloy has the following chemical composition by mass percentage: Sm 1.0%, Zn 0.5%, Zr 0.6%, Mn 0.6% and balance Mg; The preparation method of the low-alloy rare-earth magnesium alloy is as follows: (1) Pure magnesium ingots, pure zinc particles, magnesium-samarium master alloy and magnesium-manganese master alloy are loaded into a graphite crucible, then vacuum melted and then cast to obtain ingots; (2) The ingot obtained in step (1) is machined to remove the surface oxide scale and defects, and then placed in a box-type resistance furnace for homogenization treatment. It is then machined into a cylinder with a diameter of 35 mm. Next, a lubricant is applied to the surface of the billet. Then, the billet and the extrusion die (die base, die pad) are placed in a heating furnace for preheating. The preheated billet and die are quickly assembled onto the extruder for hot extrusion. The extruded sheet is straightened out through the guide frame and naturally cooled to room temperature in the air. The unstable deformation at the head and tail is removed to obtain a low-alloy rare earth magnesium alloy sheet. The holding temperature of the homogenization treatment is 400℃ and the holding time of the homogenization treatment is 6h. The cooling method of the homogenization treatment is to cool to room temperature with the furnace. The preheating temperature of the billet is 450℃ and the preheating time is 1h. The preheating temperature of the die is 350℃ and the preheating time is 1h. The hot extrusion temperature is 450℃, the hot extrusion speed is 1mm / s, and the extrusion ratio is 17.5:1.

[0052] Comparative Example 1 (Mg-1Sm-0.5Zn) The rare earth magnesium alloy has the following chemical composition by mass percentage: Sm 1.0%, Zn 0.5% and balance Mg; The preparation method of the rare earth magnesium alloy is as follows: (1) Pure magnesium ingots, pure zinc particles and magnesium-samarium master alloy are loaded into a graphite crucible, then vacuum melted and then cast to obtain an ingot; other operations are the same as in Example 1.

[0053] SEM image of the low-alloyed rare-earth magnesium alloy prepared in Example 1 is shown below. Figure 1 As shown.

[0054] from Figure 1 It can be seen that the addition of trace amounts of Zr and Mn elements will form a banded structure distributed along the ED direction after extrusion. This structure and the matrix form a sandwich-like structure, which can effectively reflect and absorb incident electromagnetic waves multiple times, thus achieving a good electromagnetic shielding effect.

[0055] The IPF diagram of the low-alloyed rare-earth magnesium alloy prepared in Example 1 is shown below. Figure 2 As shown; the grain size statistics of the low-alloyed rare-earth magnesium alloy prepared in Example 1 are shown in the figure. Figure 3 As shown.

[0056] The IPF diagram of the rare earth magnesium alloy prepared in Comparative Example 1 is shown below. Figure 4 As shown in the figure; the grain size statistics of the rare earth magnesium alloy prepared in Comparative Example 1 are shown in the figure. Figure 5 As shown.

[0057] from Figures 2-5 It can be seen that the addition of trace amounts of Zr and Mn elements significantly refines the grain size of the alloy, reducing the average grain size from 11.86 μm to 1.45 μm, thus achieving a good grain refinement strengthening effect.

[0058] The mechanical properties and electromagnetic shielding effectiveness of the low-alloyed rare-earth magnesium alloy prepared in Example 1 and the rare-earth magnesium alloy prepared in Comparative Example 1 were tested, and the results are as follows: Figures 6-7 As shown; the mechanical properties are obtained from a tensile test at a tensile rate of 1×10⁻⁶. -3 s -1 The electromagnetic shielding effectiveness was tested using the DR-S04 micro coaxial shielding effectiveness testing device. The sample was a circular disc with a diameter of 16 mm and a thickness of 2 mm.

[0059] Figure 6 The tensile strength and yield strength of the low-alloyed rare earth magnesium alloy prepared in Example 1 and the rare earth magnesium alloy prepared in Comparative Example 1 are compared. Figure 7 This is a comparison chart of the electromagnetic shielding effectiveness of the low-alloy rare-earth magnesium alloy prepared in Example 1 and the rare-earth magnesium alloy prepared in Comparative Example 1.

[0060] from Figure 6 It can be seen that the low-alloy rare earth magnesium alloy prepared by this invention has excellent tensile strength and yield strength.

[0061] from Figure 7 It can be seen that the low-alloy rare-earth magnesium alloy prepared by this invention has excellent electromagnetic shielding performance.

[0062] As can be seen from the above embodiments and comparative examples, the low-alloy rare-earth magnesium alloy provided by the present invention has both high strength and high electromagnetic shielding performance.

[0063] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A low-alloy rare-earth magnesium alloy possessing both high strength and high electromagnetic shielding performance, characterized in that, By mass percentage, it includes the following chemical components: Sm 0.5~1.5%, Zn 0.3~0.7%, Zr 0.4~0.6%, Mn 0.2~0.6% and the balance Mg.

2. The low-alloy rare-earth magnesium alloy according to claim 1, characterized in that, The chemical composition, by mass percentage, includes the following: Sm 0.8-1.2%, Zn 0.4-0.6%, Zr 0.5-0.6%, Mn 0.5-0.6%, and the balance Mg.

3. The low-alloy rare-earth magnesium alloy according to claim 1 or 2, characterized in that, The chemical composition, by mass percentage, includes the following: Sm 1.0%, Zn 0.5%, Zr 0.6%, Mn 0.6%, and the balance Mg.

4. The method for preparing the low-alloyed rare-earth magnesium alloy with high strength and high electromagnetic shielding performance as described in any one of claims 1 to 3, characterized in that, Includes the following steps: (1) The alloy raw materials are melted and cast in sequence to obtain ingots; (2) The ingots obtained in step (1) are subjected to homogenization treatment and hot extrusion in sequence to obtain a low-alloy rare earth magnesium alloy with both high strength and high electromagnetic shielding performance.

5. The preparation method according to claim 4, characterized in that, The melting in step (1) is vacuum melting.

6. The preparation method according to claim 4, characterized in that, The heat preservation temperature for homogenization treatment in step (2) is 380~420℃, and the heat preservation time for homogenization treatment is 4~8h.

7. The preparation method according to claim 4, characterized in that, The step (2) includes preheating the billet before hot extrusion; the preheating temperature is 430~470℃ and the preheating time is 1~2h.

8. The preparation method according to claim 4, characterized in that, The step (2) includes preheating the mold before hot extrusion; the preheating temperature is 350~400℃ and the preheating time is ≥1h.

9. The preparation method according to claim 4, characterized in that, In step (2), the temperature of hot extrusion is 400~500℃ and the speed of hot extrusion is 0.5~2mm / s.

10. The preparation method according to claim 4, characterized in that, The extrusion ratio of hot extrusion in step (2) is (15~30):1.

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