Aluminum / magnesium bimetallic material based on high-entropy alloy composite coating and preparation method thereof

Abstract

The application belongs to the field of aluminum / magnesium bimetallic material preparation, and discloses an aluminum / magnesium bimetallic material based on a high-entropy alloy composite coating and a preparation method thereof, which comprises the following steps: a high-entropy alloy layer and a pure metal layer are prepared on the surface of an aluminum alloy insert in sequence by using thermal spraying; magnesium alloy liquid is poured into a casting mold with the aluminum alloy insert, the magnesium alloy liquid is in contact with the pure metal layer, and an aluminum / magnesium bimetallic material is obtained after cooling and solidification. The application completely prevents the generation of Al-Mg intermetallic compounds in the aluminum / magnesium bimetallic interface, forms a bimetallic interface mainly in the form of a solid solution, solves the problem of poor bonding between a single high-entropy alloy coating and the magnesium side, and further obtains an aluminum / magnesium bimetallic material with higher mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of aluminum / magnesium bimetallic material preparation, and more specifically, relates to an aluminum / magnesium bimetallic material based on a high-entropy alloy composite coating and its preparation method. Background Technology

[0002] Aluminum / magnesium bimetallic composites combine the advantages of both aluminum and magnesium, finding wide application in aerospace, weaponry, and automotive industries. However, the aluminum / magnesium bimetallic interface is prone to forming brittle and hard Al-Mg intermetallic compounds, significantly reducing the mechanical properties of the bimetal. Common methods to improve the microstructure of the bimetallic interface include alloying, adding metal interlayers, and increasing the external force field. Compared to other methods, adding metal interlayers effectively prevents direct contact between Al and Mg, greatly reducing the formation of Al-Mg intermetallic compounds. However, the introduction of pure metal interlayers can lead to the formation of more diverse intermetallic compounds with Al and Mg, potentially negatively impacting interface properties.

[0003] High-entropy alloys are composed of multiple principal elements (five or more), each with a content of 5-35 at.%. High-entropy alloys exhibit high-entropy effects, lattice distortion effects, hysteresis diffusion effects, and a "cocktail" effect. As an interlayer, high-entropy alloys can suppress inter-element diffusion, reduce the formation of intermetallic compounds, and can form new solid solutions with some metals. The properties of these solid solutions are superior to those of intermetallic compounds. Therefore, using high-entropy alloys as an interlayer is expected to improve the mechanical properties of bimetals. However, experiments have shown that when using a high-entropy alloy coating alone, if the thickness is too thin, it cannot completely prevent the formation of Al-Mg intermetallic compounds, while a thicker coating makes it difficult to form an effective metallurgical bond between the high-entropy alloy and the magnesium side. This significantly limits the application of high-entropy alloy coatings in aluminum / magnesium bimetals and is detrimental to improving the mechanical properties of aluminum / magnesium bimetals. Summary of the Invention

[0004] In view of the above-mentioned defects or improvement needs of the prior art, the present invention provides an aluminum / magnesium bimetallic material based on a high-entropy alloy composite coating and its preparation method. The purpose is to prevent the formation of Al-Mg intermetallic compounds in the interface, and at the same time solve the problem of poor bonding between the high-entropy alloy layer and the magnesium side, thereby improving the mechanical properties of aluminum / magnesium bimetals.

[0005] To achieve the above objectives, according to one aspect of the present invention, a method for preparing an aluminum / magnesium bimetallic material based on a high-entropy alloy composite coating is proposed, comprising the following steps:

[0006] A high-entropy alloy layer and a pure metal layer were sequentially prepared on the surface of an aluminum alloy insert by thermal spraying.

[0007] Molten magnesium alloy is poured into a mold containing an aluminum alloy insert. The molten magnesium alloy comes into contact with the pure metal layer, and after cooling and solidification, an aluminum / magnesium bimetallic material is obtained.

[0008] As a further preferred embodiment, a high-entropy alloy layer is obtained by thermally spraying high-entropy alloy powder onto the surface of an aluminum alloy insert. The high-entropy alloy powder is FeCoNiCrCu powder or FeCoNiCrMn powder.

[0009] As a further preferred option, a pure metal layer is obtained by thermally spraying pure metal powder onto the surface of a high-entropy alloy layer, wherein the pure metal powder is Cu powder or Ni powder.

[0010] As a further preferred embodiment, the diameter of the high-entropy alloy powder or pure metal powder is 15μm to 53μm.

[0011] As a further preferred embodiment, the thickness of the high-entropy alloy layer is 5μm to 20μm, and the thickness of the pure metal layer is 5μm to 20μm.

[0012] As a further preferred option, the pouring temperature for the magnesium alloy molten metal is 690℃~750℃.

[0013] As a further preferred option, the volume ratio of the obtained aluminum / magnesium bimetallic material to the aluminum alloy inlay is 8:1 to 40:1.

[0014] As a further preferred option, the surface of the aluminum alloy insert is pre-treated before thermal spraying: the surface of the aluminum alloy insert is sanded with sandpaper and the oxide film is removed by alkaline washing and acid washing.

[0015] As a further preferred embodiment, the thermal spraying method is one of supersonic flame spraying, plasma spraying, or flame spraying.

[0016] According to another aspect of the present invention, an aluminum / magnesium bimetallic material based on a high-entropy alloy composite coating is provided, which is prepared by the above-described method for preparing an aluminum / magnesium bimetallic material based on a high-entropy alloy composite coating.

[0017] In summary, compared with the prior art, the above-described technical solutions conceived by this invention mainly possess the following technical advantages:

[0018] 1. This invention introduces a high-entropy alloy composite coating combining a high-entropy alloy layer and a pure metal layer, which physically isolates the aluminum alloy inlay from direct contact with molten magnesium metal, completely solving the problem of brittle Al-Mg intermetallic compounds easily forming at the aluminum / magnesium bimetallic interface. Simultaneously, the thermal spraying of the high-entropy alloy composite coating on the surface of the aluminum alloy inlay further improves its wettability with molten magnesium metal, facilitating metallurgical bonding at the aluminum / magnesium bimetallic interface and thus enhancing the mechanical properties of the aluminum / magnesium bimetal.

[0019] 2. By introducing a pure metal layer, the problem of poor bonding between the high-entropy alloy intermediate layer and the magnesium side is solved; and only between the pure metal layer and Mg will new intermetallic compounds be generated, which greatly reduces the types and quantities of intermetallic compounds, and can effectively improve the interfacial bonding strength of solid-liquid composite cast magnesium / aluminum bimetallic materials.

[0020] 3. The FeCoNiCrCu or FeCoNiCrMn high-entropy alloy layer selected in this invention can form a new high-entropy alloy with Al, rather than an intermetallic compound, thereby improving the bonding strength on the Al side; at the same time, Cu or Ni is selected as a pure metal layer, which belongs to the constituent elements of high-entropy alloys, so that the high-entropy alloy can form a solid solution structure with both the Al side and the pure metal side.

[0021] 4. Compared to pure metal composite coatings, high-entropy alloy composite coatings have a stronger inhibitory effect on element diffusion, resulting in a significant reduction in interface thickness. Simultaneously, by controlling the thickness of the pure metal layer, it is possible to ensure that most or all of the composite coating becomes a high-entropy alloy after casting, leading to a more uniform interface structure and improved performance of aluminum / magnesium bimetallic materials. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the preparation of a high-entropy alloy composite coating by supersonic flame spraying according to an embodiment of the present invention;

[0023] Figure 2 This is a schematic diagram of the interface changes after the introduction of the high-entropy alloy composite coating in an embodiment of the present invention;

[0024] Figure 3 This is a structural diagram of the device for constructing a composite cast magnesium / aluminum bimetallic material according to an embodiment of the present invention;

[0025] Figure 4 Images (a)-(d) show the interfacial microstructure of the composite cast aluminum / magnesium bimetallic material prepared in Comparative Example 1.

[0026] Figure 5 Images (a)-(c) show the interfacial microstructure of the composite cast aluminum / magnesium bimetallic material prepared in Comparative Example 2.

[0027] Figure 6 This is an image of the interface structure of the composite cast aluminum / magnesium bimetallic material prepared in Example 3 of the present invention.

[0028] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1-mold, 2-solid insert, 3-cast cavity, 4-gating system, 5-gate. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0030] This invention provides a method for preparing an aluminum / magnesium bimetallic material based on a high-entropy alloy composite coating, comprising the following steps:

[0031] S1. Treat the surface of the aluminum alloy insert, including sanding, alkaline washing, and acid washing.

[0032] Furthermore, sanding is performed using 80-grit, 240-grit, 500-grit, and 1000-grit sandpaper; alkaline washing involves immersing in a 10g / L NaOH solution for 20-30 seconds; and acid washing involves immersing in a 50% HF + 50% HNO3 solution for 20-30 seconds.

[0033] S2. A high-entropy alloy layer and a pure metal layer are sequentially prepared on the surface of the aluminum alloy inlay using thermal spraying, such as... Figure 1 As shown, the high-entropy alloy layer and the pure metal layer constitute a high-entropy alloy composite coating.

[0034] Furthermore, the thermal spraying process uses powders with a diameter between 15μm and 53μm; the high-entropy alloy powder is FeCoNiCrCu powder or FeCoNiCrMn powder, and the pure metal powder is Cu powder or Ni powder.

[0035] Furthermore, the thickness of the high-entropy alloy layer is 5μm to 20μm, and the thickness of the pure metal layer is 5μm to 20μm.

[0036] Furthermore, the thermal spraying method is one of the following: supersonic flame spraying, plasma spraying, or flame spraying.

[0037] S3. The molten magnesium alloy is poured into a mold containing aluminum alloy inserts; at this point, the interdiffusion between the aluminum side and the high-entropy alloy forms a new high-entropy alloy with a solid solution structure. A solid solution structure can also be formed between the pure metal and the high-entropy alloy. The magnesium side forms an intermetallic compound with the pure metal layer, such as... Figure 2 As shown, a composite cast aluminum / magnesium bimetallic material is obtained after cooling and solidification.

[0038] Furthermore, the pouring temperature is 690℃~750℃.

[0039] Furthermore, the volume ratio of the aluminum / magnesium bimetallic product to the aluminum alloy inlay is 8:1 to 40:1.

[0040] The present invention will be further described below with reference to specific embodiments.

[0041] Comparative Examples 1 and 2, as well as Examples 1-6, all adopted the following methods: Figure 3 The casting apparatus shown has the entire gating system 4 and the casting cavity 3 placed in the mold 1 to complete the molding process; the solid insert 2 is surrounded by the casting cavity 3, which is connected to the gating system 4, and the molten metal is poured from the gate 5.

[0042] Comparative Example 1

[0043] The preparation steps are as follows:

[0044] (1) The aluminum alloy insert is obtained by wire cutting of the A356 aluminum alloy mold, and polished with sandpaper of different grits. The surface oil and oxides are removed by alkaline washing, acid washing and other methods.

[0045] (2) Smelting AZ91D magnesium alloy, during which a mixture of sulfur hexafluoride and carbon dioxide is used for protection to prevent oxidation of the magnesium alloy.

[0046] (3) Molding and casting. The solid inlay is placed in the prepared mold with a volume ratio of 14:1 between the casting and the inlay. When the temperature of the AZ91D magnesium alloy liquid reaches 730℃, it is poured and cooled and solidified to obtain an aluminum / magnesium bimetallic material.

[0047] Comparative Example 2

[0048] The preparation steps are as follows:

[0049] (1) The aluminum alloy insert is obtained by wire cutting of the A356 aluminum alloy mold, and polished with sandpaper of different grits. The surface oil and oxides are removed by alkaline washing, acid washing and other methods.

[0050] (2) A 20μm FeCoNiCrCu high-entropy alloy coating was formed on the surface of the aluminum alloy insert by supersonic flame spraying.

[0051] (3) Smelting AZ91D magnesium alloy, during which a mixture of sulfur hexafluoride and carbon dioxide is used for protection to prevent oxidation of the magnesium alloy.

[0052] (4) Molding and casting. The solid inlay is placed in the prepared mold with a volume ratio of 14:1 between the casting and the inlay. When the temperature of the AZ91D magnesium alloy liquid reaches 730℃, it is poured and cooled and solidified to obtain an aluminum / magnesium bimetallic material.

[0053] Example 1

[0054] The preparation steps are as follows:

[0055] (1) The aluminum alloy insert is obtained by wire cutting of the A356 aluminum alloy mold, and polished with sandpaper of different grits. The surface oil and oxides are removed by alkaline washing, acid washing and other methods.

[0056] (2) A 5μm FeCoNiCrCu high-entropy alloy coating was prepared on the surface of the aluminum alloy insert by supersonic flame spraying, and then a 20μm Ni coating was sprayed on its surface.

[0057] (3) Smelting AZ91D magnesium alloy, during which a mixture of sulfur hexafluoride and carbon dioxide is used for protection to prevent oxidation of the magnesium alloy.

[0058] (4) Molding and casting. The solid inlay is placed in the prepared mold with a volume ratio of 14:1 between the casting and the inlay. When the temperature of the AZ91D magnesium alloy liquid reaches 730℃, it is poured and cooled and solidified to obtain an aluminum / magnesium bimetallic material.

[0059] Example 2

[0060] The preparation steps are as follows:

[0061] (1) The aluminum alloy insert is obtained by wire cutting of the A356 aluminum alloy mold, and polished with sandpaper of different grits. The surface oil and oxides are removed by alkaline washing, acid washing and other methods.

[0062] (2) A 20 μm FeCoNiCrCu high-entropy alloy coating was prepared on the surface of the aluminum alloy insert by supersonic flame spraying, and then a 5 μm Ni coating was sprayed on its surface.

[0063] (3) Smelting AZ91D magnesium alloy, during which a mixture of sulfur hexafluoride and carbon dioxide is used for protection to prevent oxidation of the magnesium alloy.

[0064] (4) Molding and casting. The solid inlay is placed in the prepared mold with a volume ratio of 14:1 between the casting and the inlay. When the temperature of the AZ91D magnesium alloy liquid reaches 730℃, it is poured and cooled and solidified to obtain an aluminum / magnesium bimetallic material.

[0065] Example 3

[0066] The preparation steps are as follows:

[0067] (1) The aluminum alloy insert is obtained by wire cutting of the A356 aluminum alloy mold, and polished with sandpaper of different grits. The surface oil and oxides are removed by alkaline washing, acid washing and other methods.

[0068] (2) A 10 μm FeCoNiCrCu high-entropy alloy coating was prepared on the surface of the aluminum alloy insert by plasma spraying, and then a 10 μm Cu coating was sprayed on its surface.

[0069] (3) Smelting AZ91D magnesium alloy, during which a mixture of sulfur hexafluoride and carbon dioxide is used for protection to prevent oxidation of the magnesium alloy.

[0070] (4) Molding and casting. The solid inlay is placed in the prepared mold with a volume ratio of 14:1 between the casting and the inlay. When the temperature of the AZ91D magnesium alloy liquid reaches 730℃, it is poured and cooled and solidified to obtain an aluminum / magnesium bimetallic material.

[0071] Example 4

[0072] The preparation steps are as follows:

[0073] (1) The aluminum alloy insert is obtained by wire cutting of the A356 aluminum alloy mold, and polished with sandpaper of different grits. The surface oil and oxides are removed by alkaline washing, acid washing and other methods.

[0074] (2) A 5μm FeCoNiCrMn high-entropy alloy coating was prepared on the surface of the aluminum alloy insert by flame spraying, and then a 20μm Ni coating was sprayed on its surface.

[0075] (3) Smelting AZ91D magnesium alloy, during which a mixture of sulfur hexafluoride and carbon dioxide is used for protection to prevent oxidation of the magnesium alloy.

[0076] (4) Molding and casting. The solid inlay is placed in the prepared mold with a volume ratio of 14:1 between the casting and the inlay. When the temperature of the AZ91D magnesium alloy liquid reaches 730℃, it is poured and cooled and solidified to obtain an aluminum / magnesium bimetallic material.

[0077] Example 5

[0078] The preparation steps are as follows:

[0079] (1) The aluminum alloy insert is obtained by wire cutting of the A356 aluminum alloy mold, and polished with sandpaper of different grits. The surface oil and oxides are removed by alkaline washing, acid washing and other methods.

[0080] (2) A 10 μm FeCoNiCrMn high-entropy alloy coating was prepared on the surface of the aluminum alloy insert by supersonic flame spraying, and then a 10 μm Cu coating was sprayed on its surface.

[0081] (3) Smelting AZ91D magnesium alloy, during which a mixture of sulfur hexafluoride and carbon dioxide is used for protection to prevent oxidation of the magnesium alloy.

[0082] (4) Molding and casting. The solid inlay is placed in the prepared mold with a volume ratio of 14:1 between the casting and the inlay. When the temperature of the AZ91D magnesium alloy liquid reaches 730℃, it is poured and cooled and solidified to obtain an aluminum / magnesium bimetallic material.

[0083] Example 6

[0084] The preparation steps are as follows:

[0085] (1) The aluminum alloy insert is obtained by wire cutting of the A356 aluminum alloy mold, and polished with sandpaper of different grits. The surface oil and oxides are removed by alkaline washing, acid washing and other methods.

[0086] (2) A 20 μm FeCoNiCrMn high-entropy alloy coating was prepared on the surface of the aluminum alloy insert by supersonic flame spraying, and then a 5 μm Ni coating was sprayed on its surface.

[0087] (3) Smelting AZ91D magnesium alloy, during which a mixture of sulfur hexafluoride and carbon dioxide is used for protection to prevent oxidation of the magnesium alloy.

[0088] (4) Molding and casting. The solid inlay is placed in the prepared mold with a volume ratio of 14:1 between the casting and the inlay. When the temperature of the AZ91D magnesium alloy liquid reaches 730℃, it is poured and cooled and solidified to obtain an aluminum / magnesium bimetallic material.

[0089] Comparative Example 1: Interface microstructure of uncoated aluminum / magnesium bimetal, as shown in the image. Figure 4 As shown in (a) to (d), a large number of Al-Mg intermetallic compounds exist at the interface, which severely affect the mechanical properties of the bimetal. The interface microstructure of the magnesium / aluminum bimetallic material after adding a 20 μm FeCoNiCrCu high-entropy alloy coating in Comparative Example 2 is shown in the images below. Figure 5 As shown in (a) to (c), the results indicate that after adding a 20 μm high-entropy alloy coating, the intermetallic Al-Mg compounds at the interface completely disappeared, and new Al was formed through interdiffusion between the aluminum side and the high-entropy alloy. x The FeCoNiCrCu high-entropy alloy was formed, but only a small amount of Mg-Ni-Cu mixed phase was formed on the magnesium side, failing to form an effective metallurgical bond.

[0090] The aluminum / magnesium bimetallic material obtained in Example 3 is as follows: Figure 6 As shown, after the introduction of the high-entropy alloy composite coating, a high-entropy alloy with a solid solution structure is formed near the Al side, while an intermetallic compound mainly composed of Mg2Cu is formed on the magnesium side, and the interface has good metallurgical bonding.

[0091] The shear strength of the aluminum / magnesium bimetallic interface was tested. The results showed that the shear strength of the bimetallic material with only a high-entropy alloy coating increased from approximately 32 MPa to approximately 39 MPa, an increase of 21.88%. The shear strength of the aluminum / magnesium bimetallic material with the addition of a high-entropy alloy composite coating both exceeded 50 MPa. This indicates that the high-entropy alloy composite coating solves both the problem of brittle intermetallic compounds easily forming between Al and Mg, and the problem of poor bonding on the Mg side in a single high-entropy alloy coating. The introduction of the high-entropy alloy composite coating forms a good metallurgical bonding interface dominated by solid solution, significantly improving the mechanical properties of the bimetallic material.

[0092] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing an aluminum / magnesium bimetallic material based on a high-entropy alloy composite coating, characterized in that, Includes the following steps: A high-entropy alloy layer and a pure metal layer are sequentially prepared on the surface of an aluminum alloy inlay by thermal spraying. Specifically, high-entropy alloy powder is thermally sprayed onto the surface of the aluminum alloy inlay to obtain a high-entropy alloy layer. The high-entropy alloy powder is FeCoNiCrCu powder or FeCoNiCrMn powder. Pure metal powder is thermally sprayed onto the surface of the high-entropy alloy layer to obtain a pure metal layer. The pure metal powder is Cu powder or Ni powder. Molten magnesium alloy is poured into a mold containing an aluminum alloy insert. The molten magnesium alloy comes into contact with the pure metal layer. The mutual diffusion between the aluminum side and the high-entropy alloy forms a new high-entropy alloy with a solid solution structure. A solid solution structure is also formed between the pure metal and the high-entropy alloy. An intermetallic compound is formed between the magnesium side and the pure metal layer. After cooling and solidification, an aluminum / magnesium bimetallic material is obtained.

2. The method for preparing aluminum / magnesium bimetallic materials based on high-entropy alloy composite coatings as described in claim 1, characterized in that, The diameter of the high-entropy alloy powder and pure metal powder is 15μm to 53μm.

3. The method for preparing aluminum / magnesium bimetallic materials based on high-entropy alloy composite coatings as described in claim 1, characterized in that, The thickness of the high-entropy alloy layer is 5μm to 20μm, and the thickness of the pure metal layer is 5μm to 20μm.

4. The method for preparing aluminum / magnesium bimetallic materials based on high-entropy alloy composite coatings as described in claim 1, characterized in that, When pouring molten magnesium alloy, the pouring temperature is 690℃~750℃.

5. The method for preparing aluminum / magnesium bimetallic materials based on high-entropy alloy composite coatings as described in claim 1, characterized in that, The volume ratio of the obtained aluminum / magnesium bimetallic material to the aluminum alloy inlay is 8:1 to 40:

1.

6. The method for preparing aluminum / magnesium bimetallic materials based on high-entropy alloy composite coatings as described in claim 1, characterized in that, Before thermal spraying, the surface of the aluminum alloy insert is pre-treated: the surface of the aluminum alloy insert is sanded with sandpaper and the oxide film is removed by alkaline washing and acid washing.

7. The method for preparing aluminum / magnesium bimetallic materials based on high-entropy alloy composite coatings as described in any one of claims 1-6, characterized in that, The thermal spraying method is one of supersonic flame spraying, plasma spraying, or flame spraying.

8. An aluminum / magnesium bimetallic material based on a high-entropy alloy composite coating, characterized in that, It is prepared by the method for preparing aluminum / magnesium bimetallic material based on high-entropy alloy composite coating as described in any one of claims 1-7.

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