A corrosion-resistant lightweight high-entropy alloy composite coating and its preparation method

Abstract

The present invention provides a corrosion-resistant lightweight high-entropy alloy composite coating and a preparation method thereof. The composite coating includes a lightweight high-entropy alloy layer and a transition layer. The lightweight high-entropy alloy layer is disposed on the surface of the transition layer, and the lightweight high-entropy alloy layer and the transition layer are arranged in an interlaced manner; the material of the lightweight high-entropy alloy layer is an AlZrNbTiVCr lightweight high-entropy alloy; the material of the transition layer is pure titanium. By combining the lightweight high-entropy alloy layer and the transition layer and arranging them in an interlaced manner, the defects generated in the overlapping area during the preparation of the coating are reduced. The heterogeneous interface layer formed between the layers can play a role in hindering the crack growth caused by external force impact, and it has excellent impact resistance, wear resistance and corrosion resistance, and has good engineering application value.

Description

Technical Field

[0001] The present invention relates to the technical field of surface engineering, and particularly to a corrosion-resistant lightweight high-entropy alloy composite coating and a preparation method thereof. Background Art

[0002] Advanced marine equipment is the foundation and important guarantee for the construction of a marine power country. The performance of key marine components fails due to various factors such as long-term wear, corrosion, and impact. At present, the matrix materials of key components have reached a certain performance limit. To require them to serve reliably for a long time in a harsh environment, it is necessary to further study important technical guarantees such as the surface coating technology of components. The bonding strength of traditional surface coating technologies such as thermal spraying and electroplating is relatively low. After long-term impact and mechanical action, they are prone to failure and cannot play a protective role. As a new type of surface strengthening and repair technology, directional energy deposition can greatly improve the mechanical properties such as the hardness, wear resistance, corrosion resistance, and impact resistance of the part surface, and can greatly improve the service life of the material. The directional energy deposition technology provides an effective means for the surface protection and repair of equipment parts because it can prepare a clad layer with good metallurgical bonding performance, low dilution rate, and compact microstructure.

[0003] High-entropy alloys usually have five or more main components and minor components, with equimolar or equimolar ratios, and have attracted wide attention due to their excellent strength and ductility, excellent wear resistance, and extraordinary corrosion resistance. In addition, the cocktail of high-entropy alloys shows that by selecting various specific elements, high-entropy alloys with different characteristics can be obtained, and they have broad application prospects in the fields of aerospace, ocean, nuclear reactors, etc. However, due to the difference in melting points of its constituent elements and stress concentration in the bonding region, the effect is often not ideal and the forming quality is poor during the coating preparation process.

[0004] Chinese Patent CN117684163A, "A Wear-Resistant and Impact-Resistant Bionic Structure Composite Coating and a Preparation Method Thereof", discloses a wear-resistant and impact-resistant bionic structure composite coating. Through the "brick-mud" bionic shell-like structure design with alternating hard and soft in the horizontal and vertical directions and the design of a duplex eutectic high-entropy alloy and high-hardness ceramic materials, it has excellent impact resistance, wear resistance, and corrosion resistance. However, this coating pursues too much the wear-resistant and drag-reducing performance, and its impact resistance and corrosion resistance still need to be further improved.

[0005] Therefore, it is of great significance to develop a corrosion-resistant lightweight high-entropy alloy composite coating with excellent impact resistance and corrosion resistance and reasonable structure design and a preparation method thereof. Summary of the Invention

[0006] In view of the problem that the existing high-entropy alloy composite coatings still need to further improve their impact resistance and corrosion resistance, the present invention provides a corrosion-resistant lightweight high-entropy alloy composite coating, which is composed of a high-strength AlZrNbTiVCr lightweight high-entropy alloy layer and a pure titanium transition layer with good wettability and matching. The layers are arranged in an interlaced manner, reducing the defects generated in the overlapping area during the coating preparation process. The heterogeneous interface layer formed between the layers can hinder the crack growth caused by external force impact, having excellent impact resistance, wear resistance and corrosion resistance, and having good engineering application value, with good application prospects in the fields of marine equipment, rail transit, metallurgy, etc.

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

[0008] A corrosion-resistant lightweight high-entropy alloy composite coating, comprising a lightweight high-entropy alloy layer and a transition layer. The lightweight high-entropy alloy layer is disposed on the surface of the transition layer, and the lightweight high-entropy alloy layer and the transition layer are arranged in an interlaced manner; the material of the lightweight high-entropy alloy layer is AlZrNbTiVCr lightweight high-entropy alloy; the material of the transition layer is pure titanium.

[0009] In the present invention, the layers of the lightweight high-entropy alloy layer and the transition layer are arranged in an interlaced manner, thereby reducing the defects generated in the overlapping area during the coating preparation process. The material of the lightweight high-entropy alloy layer is a six-element AlZrNbTiVCr lightweight high-entropy alloy formed by the synergistic compounding of Al, Zr, Nb, Ti, V, and Cr, containing a large number of lightweight elements, having better performance without excessive increase in the weight of the parts, and simultaneously having a high-entropy effect in thermodynamics, a lattice distortion effect in structure, a sluggish diffusion effect in kinetics, and a cocktail effect in performance, and thus having excellent wear resistance, high strength, radiation resistance and other excellent properties. The transition layer uses pure titanium material. On the one hand, pure titanium and the AlZrNbTiVCr lightweight high-entropy alloy have good wettability and matching, laying a good material foundation for the formation of good metallurgical bonding between the coatings, and at the same time solving the stress concentration problems of the direct bonding of the high-strength lightweight high-entropy alloy layer and the direct bonding between the lightweight high-entropy alloy layer and the substrate; on the other hand, during the service process of the coating, it is often subjected to the coupled action of wear and large impact, and the coating bonding area is prone to peeling and cracking, affecting its service life. The pure titanium material as the transition layer can effectively delay the external force impact and improve its comprehensive performance. At the same time, a heterogeneous interface layer is formed at the junction of the lightweight high-entropy alloy layer and the transition layer, and such an interface layer can hinder the crack growth caused by external force impact. Therefore, the corrosion-resistant lightweight high-entropy alloy composite coating of the present invention has excellent impact resistance, wear resistance and corrosion resistance.

[0010] Furthermore, the lightweight high-entropy alloy layer and the transition layer are both provided with multiple layers. A single-layer lightweight high-entropy alloy layer is disposed between two adjacent transition layers, and the surface layer of any lightweight high-entropy alloy layer is perpendicular to the intersecting transition layer, and the surface layer of any lightweight high-entropy alloy layer is perpendicular to the intersecting transition layer.

[0011] The multi-layer structure design ensures that there is sufficient buffering in the coating bonding area under harsh and complex working conditions such as wear and impact, which can extend its service life.

[0012] Furthermore, the composite coating is a four-layer composite coating. The four-layer composite coating includes a first lightweight high-entropy alloy layer, a second transition layer, and a second lightweight high-entropy alloy layer which are sequentially stacked from bottom to top. The first lightweight high-entropy alloy layer is disposed between the first transition layer and the second process layer. The first transition layer is vertically disposed on the lower surface of the first lightweight high-entropy alloy layer; the second transition layer is vertically disposed on the upper surface of the first lightweight high-entropy alloy layer, and the lower surface of the second lightweight high-entropy alloy layer is vertically disposed on the upper surface of the second transition layer.

[0013] Furthermore, the total thickness of the composite coating is 2-3 mm; the thickness ratio of the lightweight high-entropy alloy layer to the transition layer is (0.5-0.8):(0.6-1).

[0014] Furthermore, the AlZrNbTiVCr lightweight high-entropy alloy is a single BCC structural phase.

[0015] The AlZrNbTiVCr lightweight high-entropy alloy of the present invention has a BCC solid solution with a single structural phase and relatively high strength. Compared with the FCC high-entropy alloy with a single structural phase and the high-entropy alloy with a dual-phase of FCC and BCC, the lightweight high-entropy alloy layer of the present invention has higher microhardness and wear resistance.

[0016] Another object of the present invention is to provide a method for preparing a corrosion-resistant lightweight high-entropy alloy composite coating.

[0017] A method for preparing the above-mentioned corrosion-resistant lightweight high-entropy alloy composite coating includes the following steps:

[0018] S1. Prepare AlZrNbTiVCr lightweight high-entropy alloy powder and pure titanium powder for use;

[0019] S2. Use directional energy deposition to sequentially deposit pure titanium powder and AlZrNbTiVCr lightweight high-entropy alloy powder on the surface of the substrate, layer by layer to prepare the coating, and the additive manufacturing direction of the next layer is rotated by a certain angle relative to the previous layer, and the angle range is 45-135°, thus obtaining the corrosion-resistant lightweight high-entropy alloy composite coating.

[0020] Furthermore, the AlZrNbTiVCr lightweight high-entropy alloy powder described in S1 contains the following elements by mass fraction: 4-6% Al, 6-9% Zr, 20-25% Nb, 40-50% Ti, 12-16% V, 4-6% Cr.

[0021] In the present invention, the compounding of Al, Zr, Nb, Ti, V, and Cr with the above ratios makes the powder composition uniform. During the directional energy deposition process, a BCC solid solution phase with high thermal stability can be formed, improving the strength of the coating material and having high-entropy effects thermodynamically, lattice distortion effects structurally, sluggish diffusion effects kinetically, and cocktail effects in terms of performance. Consequently, it has excellent properties such as high wear resistance, high strength, and radiation resistance.

[0022] Furthermore, the sphericity of the AlZrNbTiVCr lightweight high-entropy alloy powder described in S1 is 90-99%, the particle size distribution range is 45-150 μm, Dv(10) is 45-50 μm, Dv(50) is 55-75 μm, and Dv(90) is 90-110 μm; the sphericity of the pure titanium powder described in S1 is 90-99%, and the purity is 99.9%.

[0023] In the present invention, if the sphericity of the AlZrNbTiVCr lightweight high-entropy alloy powder is less than 90%, the coating forming quality is poor and there are many defects; when the sphericity is 90-99%, the coating forming quality is better and the coating performance is better. In the present invention, the particle size of the AlZrNbTiVCr lightweight high-entropy alloy powder affects the coating performance. For example, if D90 is less than 90 μm, the overall powder is too fine, resulting in poor powder feeding effect and thus poor coating forming quality; if D90 is greater than 110 μm, the overall powder is too coarse, resulting in the laser being insufficient to fully melt the powder and thus poor coating forming quality. Therefore, controlling the above parameters within a certain range in the present invention can better improve the quality and performance of the coating forming.

[0024] Furthermore, the process parameters of the directional energy deposition described in S2 include: laser power of 2200-3500 W, spot diameter of 3-5 mm, powder feeding rate of 10-25 g / min, laser scanning rate of 6-14 mm / s, and overlapping rate of 30-60%.

[0025] In the present invention, during the preparation of the corrosion-resistant lightweight high-entropy alloy composite coating by directed energy deposition, if the laser power is too small, the powder will not melt sufficiently, and if the laser power is too large, the powder will be overburned, thus affecting the coating forming quality. By simultaneously controlling the laser power, laser scanning rate, powder feeding rate, spot diameter, and overlapping rate within a certain range, it is beneficial to further improve the quality of the corrosion-resistant lightweight high-entropy alloy composite coating, thereby improving the impact resistance and wear resistance of the coating.

[0026] Furthermore, before the directed energy deposition described in S2, there is also a step of induction preheating treatment of the substrate, with a preheating temperature of 200 - 400 °C and a time of 20 - 40 min; the directed energy deposition described in S2 uses Ar and / or He as the protective gas.

[0027] In the present invention, preheating the substrate before directed energy deposition enables better wettability between the powder and the substrate during directed energy deposition, while reducing the stress concentration at the interface between the coating and the substrate during directed energy deposition and preventing cracking. In the present invention, inert gas protection is carried out during directed energy deposition to prevent the powder from being oxidized during directed energy deposition and affecting the coating forming quality.

[0028] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0029] In the corrosion-resistant lightweight high-entropy alloy composite coating of the present invention, the lightweight high-entropy alloy layer and the transition layer are arranged in an interlaced manner with each other, so that each layer is staggered from the layer below during preparation, thereby reducing the defects generated in the overlapping area during the preparation of the composite coating, and thus improving the overall strength, impact resistance, and corrosion resistance of the corrosion-resistant lightweight high-entropy alloy composite coating.

[0030] In the corrosion-resistant lightweight high-entropy alloy composite coating, the raw material of the lightweight high-entropy alloy layer is the AlZrNbTiVCr lightweight high-entropy alloy powder obtained by the synergistic compounding of Al, Zr, Nb, Ti, V, and Cr, which contains a large number of lightweight elements. After design and preparation, the density of the alloy powder is as low as 4.12 g / cm 3, it has better performance without significantly increasing the weight of the parts and has good application prospects in lightweight equipment parts; the lightweight high-entropy alloy layer prepared from AlZrNbTiVCr lightweight high-entropy alloy powder by the directed energy deposition technique has a single BCC structure phase with high strength. Nb can reduce the superheat sensitivity and temper brittleness of the alloy, improve the strength, and prevent intergranular corrosion. At the same time, the V element can refine the grains, thus better improving the performance of the lightweight high-entropy alloy layer. As lightweight elements, Al and Ti reduce the mass of the lightweight high-entropy alloy layer on the one hand and promote the formation of the BCC structure phase on the other hand, enabling it to have higher strength. In particular, the Zr element has good oxide film formation ability, enabling the lightweight high-entropy alloy layer to form a dense oxide film on the surface of the substrate material, thus effectively preventing the substrate material from reacting with substances such as oxygen and water in the external environment. This can not only improve the oxidation resistance of the substrate material and extend its service life but also improve the corrosion resistance of the substrate material, making it have better stability and a longer service life in harsh environments.

[0031] The transition layer is made of pure titanium material. On the one hand, pure titanium and the AlZrNbTiVCr lightweight high-entropy alloy have good wettability and matching, and it cleverly solves the stress concentration problems of the direct bonding of the high-strength lightweight high-entropy alloy layer and the direct bonding between the lightweight high-entropy alloy layer and the substrate without introducing other structure phases, thus avoiding phenomena such as easy peeling and cracking in the coating bonding area and affecting its service life. On the other hand, because the hardness of the pure titanium metal coating is relatively low and its plasticity is good, using pure titanium material as the transition layer can effectively delay the external force impact and improve its comprehensive performance.

[0032] At the same time, a heterogeneous interface layer is formed at the junction of the lightweight high-entropy alloy layer and the transition layer. Such an interface layer can play a role in hindering the crack growth generated by external force impact. When the crack propagates disorderly in the complex structure of the hard and soft metal overlapping and interweaving, it will deflect repeatedly due to the different strengths of the materials on both sides of the densely distributed interweaving interface, and thus can achieve the purpose of consuming a large amount of fracture energy and absorbing external impact energy.

[0033] The present invention uses the directed energy deposition method to prepare a corrosion-resistant lightweight high-entropy alloy composite coating, which can form excellent metallurgical bonding, can realize the integrated rapid manufacturing of the composite coating, and has the advantages of customization, high production efficiency, high material utilization rate, low production cost, good forming quality, excellent interface bonding, high stability, etc. It has good engineering application value, is widely applicable to the surface protection and remanufacturing of vulnerable equipment parts in extreme environments, and has important economic value and promotion significance. Brief Description of the Drawings

[0034] The invention will be further described with reference to the accompanying drawings. However, the embodiments shown in the drawings do not constitute any limitation to the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on the following drawings without creative efforts.

[0035] Figure 1 It is a schematic diagram of the corrosion-resistant lightweight high-entropy alloy composite coating of Embodiment 1 of this application.

[0036] Figure 2 It is a SEM image of the AlZrNbTiVCr lightweight high-entropy alloy powder of Embodiment 1 of this application.

[0037] Figure 3 It is an optical microscope image of the corrosion-resistant lightweight high-entropy alloy composite coating of Embodiment 1 of this application;

[0038] Figure 4 It is an X-ray diffraction pattern of the lightweight high-entropy alloy layer of Embodiment 1 of this application.

[0039] Reference numerals in the drawings: 1 - substrate; 2 - first transition layer; 3 - first lightweight high-entropy alloy layer; 4 - second transition layer; 5 - second lightweight high-entropy alloy layer; 6 - overlapping area. Detailed implementation manners

[0040] To better illustrate the purpose, technical solutions and advantages of the present invention, the present invention is further illustrated by the following embodiments. Obviously, the following embodiments are only a part of the embodiments of the present invention, rather than all the embodiments; it should be understood that the embodiments of the present invention are only used to illustrate the technical effects of the present invention, rather than to limit the protection scope of the present invention.

[0041] The raw materials in the embodiments can all be obtained commercially; unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the technical field.

[0042] Embodiment 1

[0043] A preparation method of a corrosion-resistant lightweight high-entropy alloy composite coating, comprising the following steps:

[0044] S1. Prepare AlZrNbTiVCr lightweight high-entropy alloy powder, containing 4% Al, 7% Zr, 25% Nb, 45% Ti, 14% V, 5% Cr, with a sphericity ≥ 90%, a particle size distribution range of 45 - 150 μm, Dv(10) being 50 μm, Dv(50) being 60 μm, Dv(90) being 100 μm, and pure titanium powder, with a sphericity ≥ 90% and a purity of 99.9%, for later use;

[0045] S2. Preheat the substrate using an electromagnetic induction device, preheat it at 350 °C for 20 min, and under Ar protection, deposit pure titanium powder and AlZrNbTiVCr lightweight high-entropy alloy powder on the substrate surface in sequence by directed energy deposition. The laser power is 2500 W, the spot diameter is 4 mm, the powder feeding rate is 15 g / min, the laser scanning rate is 10 mm / s, the overlapping rate is 50%, and the coating is prepared layer by layer. Moreover, the additive manufacturing direction of the next layer is rotated 90° relative to the previous layer, thus obtaining the corrosion-resistant lightweight high-entropy alloy composite coating.

[0046] The corrosion-resistant lightweight high-entropy alloy composite coating includes a four-layer structure, which are, from bottom to top, substrate 1 and a first transition layer 2, a first lightweight high-entropy alloy layer 3, a second transition layer 4, and a second lightweight high-entropy alloy layer 5 that are stacked in sequence, as well as the overlapping area 6 therein; any one of the lightweight high-entropy alloy layers is staggered 90° in the horizontal direction from the transition layer on its upper end face and / or lower end face. The total thickness of the coating is 3 mm, and the thickness ratio of the lightweight high-entropy alloy layer to the transition layer is 0.5:1. The AlZrNbTiVCr lightweight high-entropy alloy is a single BCC structure phase.

[0047] Example 2

[0048] A preparation method of a corrosion-resistant lightweight high-entropy alloy composite coating, the steps not specifically described are the same as those in Example 1, and the differences are as follows:

[0049] Compared with Example 1, the AlZrNbTiVCr lightweight high-entropy alloy powder described in S1 contains 6% Al, 9% Zr, 25% Nb, 40% Ti, 16% V, and 4% Cr.

[0050] Example 3

[0051] A preparation method of a corrosion-resistant lightweight high-entropy alloy composite coating, the steps not specifically described are the same as those in Example 1, and the differences are as follows:

[0052] Compared with Example 1, the AlZrNbTiVCr lightweight high-entropy alloy powder described in S1 contains 6% Al, 8% Zr, 20% Nb, 50% Ti, 12% V, and 4% Cr, and the others are the same as those in Example 1.

[0053] Example 4

[0054] A preparation method of a corrosion-resistant lightweight high-entropy alloy composite coating, the steps not specifically described are the same as those in Example 1, and the differences are as follows:

[0055] Compared with Example 1, the AlZrNbTiVCr lightweight high-entropy alloy powder described in S1 contains 4% Al, 6% Zr, 25% Nb, 45% Ti, 16% V, and 4% Cr.

[0056] Example 5

[0057] A method for preparing a corrosion-resistant lightweight high-entropy alloy composite coating. The steps not specifically described are the same as those in Example 2, except that:

[0058] Compared with Example 2, the sphericity of the AlZrNbTiVCr lightweight high-entropy alloy powder described in S1 is ≥95%, the particle size distribution range is 45 - 150 μm, Dv(10) is 45 μm, Dv(50) is 60 μm, and Dv(90) is 90 μm; the preheating temperature described in S2 is 300 °C, the laser power is 3000 W, the spot diameter is 5 mm, the powder feeding rate is 25 g / min, the laser scanning rate is 12 mm / s, and the overlapping rate is 30%; the total thickness of the coating is 2 mm.

[0059] Example 6

[0060] A method for preparing a corrosion-resistant lightweight high-entropy alloy composite coating. The steps not specifically described are the same as those in Example 3, except that:

[0061] Compared with Example 3, the sphericity of the AlZrNbTiVCr lightweight high-entropy alloy powder described in S1 is ≥95%, the particle size distribution range is 45 - 150 μm, Dv(10) is 50 μm, Dv(50) is 75 μm, and Dv(90) is 110 μm; the preheating temperature described in S2 is 400 °C, the laser power is 3500 W, the spot diameter is 3 mm, the powder feeding rate is 10 g / min, the laser scanning rate is 8 mm / s, and the overlapping rate is 40%.

[0062] Example 7

[0063] A method for preparing a corrosion-resistant lightweight high-entropy alloy composite coating. The steps not specifically described are the same as those in Example 1, except that:

[0064] Compared with Example 1, the laser scanning rate described in S2 is 6 mm / s.

[0065] Example 8

[0066] A method for preparing a corrosion-resistant lightweight high-entropy alloy composite coating. The steps not specifically described are the same as those in Example 1, except that:

[0067] Compared with Example 1, the corrosion-resistant lightweight high-entropy alloy composite coating is a six-layer structure, which is successively a transition layer and a lightweight high-entropy alloy layer stacked from bottom to top.

[0068] Example 9

[0069] A preparation method of a corrosion-resistant lightweight high-entropy alloy composite coating. The steps not specifically described are the same as those in Example 1, except that:

[0070] Compared with Example 1, the laser power in S2 is 2200 W.

[0071] Comparative Example 1

[0072] A preparation method of a corrosion-resistant lightweight high-entropy alloy composite coating. The steps not specifically described are the same as those in Example 1, except that:

[0073] Compared with Example 1, the AlZrNbTiVCr lightweight high-entropy alloy powder described in S1 of this comparative example contains 10% Al, 10% Zr, 20% Nb, 50% Ti, 6% V, and 4% Cr.

[0074] Comparative Example 2

[0075] A preparation method of a corrosion-resistant lightweight high-entropy alloy composite coating. The steps not specifically described are the same as those in Example 1, except that:

[0076] Compared with Example 1, the AlZrNbTiVCr lightweight high-entropy alloy powder described in S1 of this comparative example contains 20% Al, 20% Zr, 20% Nb, 20% Ti, 10% V, and 10% Cr.

[0077] Comparative Example 3

[0078] A preparation method of a corrosion-resistant lightweight high-entropy alloy composite coating. The steps not specifically described are the same as those in Example 1, except that:

[0079] Compared with Example 1, the AlZrNbTiVCr lightweight high-entropy alloy powder described in S1 of this comparative example contains 30% Al, 10% Zr, 0% Nb, 50% Ti, 5% V, and 5% Cr.

[0080] Comparative Example 4

[0081] A preparation method of a corrosion-resistant lightweight high-entropy alloy composite coating. The steps not specifically described are the same as those in Example 1, except that:

[0082] Compared with Example 1, the sphericity of the AlZrNbTiVCr lightweight high-entropy alloy powder described in S1 of this comparative example is 50%.

[0083] Comparative Example 5

[0084] A preparation method of a corrosion-resistant lightweight high-entropy alloy composite coating. The steps not specifically described are the same as those in Example 1, except that:

[0085] Compared with Example 1, the coating material in this comparative example is a single-layer lightweight high-entropy alloy coating.

[0086] Comparative Example 6

[0087] A method for preparing a corrosion-resistant lightweight high-entropy alloy composite coating, the steps not specifically described are the same as those in Example 1, and the differences are as follows:

[0088] Compared with Example 1, the coating material in this comparative example is a double-layer lightweight high-entropy alloy coating.

[0089] Comparative Example 7

[0090] A method for preparing a corrosion-resistant lightweight high-entropy alloy composite coating, the steps not specifically described are the same as those in Example 1, and the differences are as follows:

[0091] Compared with Example 1, the coating material in this comparative example has a three-layer structure, with a lightweight high-entropy alloy coating in the middle layer, and pure titanium metal coatings in both the bottom layer and the top layer.

[0092] Comparative Example 8

[0093] A method for preparing a corrosion-resistant lightweight high-entropy alloy composite coating, the steps not specifically described are the same as those in Example 1, and the differences are as follows:

[0094] Compared with Example 1, the overlapping rate of step S2 in this comparative example is 20%.

[0095] Comparative Example 9

[0096] A method for preparing a corrosion-resistant lightweight high-entropy alloy composite coating, the steps not specifically described are the same as those in Example 1, and the differences are as follows:

[0097] Compared with Example 1, the laser power in step S2 of this comparative example is 1800 W.

[0098] Comparative Example 10

[0099] A method for preparing a corrosion-resistant lightweight high-entropy alloy composite coating, the steps not specifically described are the same as those in Example 1, and the differences are as follows:

[0100] Compared with Example 1, the laser power in step S2 of this comparative example is 4500 W.

[0101] Comparative Example 11

[0102] A method for preparing a corrosion-resistant lightweight high-entropy alloy composite coating, the steps not specifically described are the same as those in Example 1, and the differences are as follows:

[0103] Compared with Example 1, the scanning speed in step S2 of this comparative example is 20 mm / s.

[0104] Comparative Example 12

[0105] A preparation method of a corrosion-resistant lightweight high-entropy alloy composite coating. The steps not specifically described are the same as those in Example 1, except that:

[0106] Compared with Example 1, the scanning speed in step S2 of this comparative example is 2 mm / s.

[0107] Comparative Example 13

[0108] A preparation method of a corrosion-resistant lightweight high-entropy alloy composite coating. The steps not specifically described are the same as those in Example 1, except that:

[0109] Compared with Example 1, the substrate is not preheated before directional energy deposition in step S2 of this comparative example.

[0110] Comparative Example 1

[0111] A preparation method of a corrosion-resistant lightweight high-entropy alloy composite coating. The steps not specifically described are the same as those in Example 1, except that:

[0112] Compared with Example 1, no atmosphere protection is carried out during the directional energy deposition process in step S2 of this comparative example.

[0113] Comparative Example 15

[0114] A preparation method of a corrosion-resistant lightweight high-entropy alloy composite coating. The steps not specifically described are the same as those in Example 1, except that:

[0115] Compared with Example 1, the preparation path of the composite coating in step S2 of this comparative example remains the same. The additive manufacturing direction of the next layer does not rotate 90° relative to the previous layer, and there is no interlaced structure in the horizontal direction.

[0116] Perform performance tests on the above samples. The experimental test methods are as follows:

[0117] Perform microscopic analysis on Example 1, Figure 2 This is the electron microscope image of the AlZrNbTiVCr lightweight high-entropy alloy powder of Example 1 of this application. It can be seen from the figure that the powder of the present invention has high sphericity and uniform particle size distribution, and is very suitable for use in the directional energy deposition technology; Figure 3 This is the optical microscope image of the corrosion-resistant lightweight high-entropy alloy composite coating of Example 1 of this application; it can be seen that the corrosion-resistant lightweight high-entropy alloy composite coating obtained by directional energy deposition in the present invention has good forming quality and no defects; Figure 4 This is the X-ray diffraction pattern of the lightweight high-entropy alloy layer of Example 1 of this application. It can be seen from the figure that the lightweight high-entropy alloy layer of the present invention has a single BCC solid solution phase structure.

[0118] The test results of the remaining examples are basically the same.

[0119] Test method for coating forming quality: Determine with reference to the national standard "GB / T 36591-2018"

[0120] Test method for wear loss: Determine with reference to the national standard "GB / T 12444-2006"

[0121] Test method for self-corrosion current density: Determine with reference to the national standard "GB / T 40299-2021"

[0122] Test method for microhardness: Determine with reference to the national standard "GB / T 4340.1-2009"

[0123] Test method for density: Determine with reference to the national standard "GB / T1479.1-2011"

[0124] Test method for impact energy: Determine with reference to the national standard "GB / T 2423.5"

[0125] Among them, the wear loss represents the wear and corrosion resistance of the coating. The smaller the value, the better the wear and corrosion resistance of the coating; the self-corrosion current density represents the corrosion resistance of the coating. The smaller the value, the better the corrosion resistance of the coating; the microhardness represents the strength of the coating. The larger the value, the higher the strength of the coating; the density represents the quality of the coating. The smaller the value, the lighter the coating; the impact energy represents the impact resistance. The larger the value, the better the impact resistance of the coating. The test results of Examples 1-8 and Comparative Examples 1-15 are shown in the following table:

[0126] Table 1 Test results of Examples 1-6 and Comparative Examples 1-11

[0127]

[0128] It can be seen from Table 1 that the forming quality of each example of the present invention is good, without defects. The wear loss is all lower than 0.015 g, the self-corrosion current density can reach as low as 2.057×10 -8 A / cm 2 , the microhardness can reach as high as 480 HV, the density can be as low as 4.12 g / cm 3 , and the impact energy is all above 100 J. Compared with each comparative example, it has outstanding comprehensive performance, indicating that the corrosion-resistant lightweight high-entropy alloy composite coating of the present invention has excellent wear and corrosion resistance, corrosion resistance and impact resistance.

[0129] For the AlZrNbTiVCr lightweight high-entropy alloy powders of Comparative Examples 1-3, the contents of each element exceed the range, the coating forming quality is poor, and there are many defects; for the AlZrNbTiVCr lightweight high-entropy alloy powder of Comparative Example 4, the sphericity is low. Although the density is low and the quality is light, the coating forming quality is poor, there are many defects, the wear loss is large, and the wear resistance is poor; for Comparative Examples 5 and 6, there is no pure titanium transition layer, and the corrosion resistance and impact resistance are poor; for Comparative Example 7, it is a three-layer structure, and the impact resistance is higher than that of other comparative examples, but the wear loss is large, the wear resistance is poor, the microhardness is low, and the strength is poor; for Comparative Examples 8-12, the process parameters of direct energy deposition exceed the range, resulting in poor coating forming quality, many defects, poor wear resistance, and poor impact resistance; for Comparative Example 13, there is no preheating step before direct energy deposition, the stress concentration at the interface between the coating and the substrate is high, there are many cracks, the coating forming quality is poor, and there are many defects; for Comparative Example 14, there is no inert gas protection, and the powder is oxidized during direct energy deposition, affecting the coating forming quality, the coating forming quality is poor, and there are many defects; for Comparative Example 15, the corrosion-resistant lightweight high-entropy alloy composite coating has no mutually perpendicular structure, and the comprehensive performance is higher than that of other comparative examples, but the corrosion resistance is poor and far from comparable to each embodiment.

[0130] In summary, the corrosion-resistant lightweight high-entropy alloy composite coating prepared by the present invention by direct energy deposition method, through the interlaced arrangement between the lightweight high-entropy alloy layer and the transition layer, reduces the defects generated in the overlapping area during the coating preparation process. The lightweight high-entropy alloy layer has a high-strength single BCC structure phase and contains a large number of lightweight elements, with better performance without excessive increase in the weight of the parts, and has good application prospects in lightweight equipment parts; the pure titanium material used in the transition layer has good wettability and matching with the AlZrNbTiVCr lightweight high-entropy alloy, and cleverly solves the stress concentration problems of the direct bonding of the high-strength lightweight high-entropy alloy layer and the direct bonding between the lightweight high-entropy alloy layer and the substrate without introducing other structure phases, thus avoiding the phenomena such as easy shedding and cracking in the coating bonding area, which affect its service life; and because the hardness of the pure titanium metal coating is low and its plasticity is good, using the pure titanium material as the transition layer can effectively delay the external force impact and improve its comprehensive performance. At the same time, a heterogeneous interface layer is formed at the junction of the lightweight high-entropy alloy layer and the transition layer. Such an interface layer can play a role in hindering the crack growth generated by external force impact, so that when the crack propagates disorderly in the complex structure of the hard and soft metal overlapping and interweaving, it will deflect repeatedly due to the different material strengths on both sides of the densely distributed interweaving interface, and then can achieve the purpose of consuming a large amount of fracture energy and absorbing external impact energy; the corrosion-resistant lightweight high-entropy alloy composite coating of the present invention has excellent impact resistance, wear resistance and corrosion resistance, has good engineering application value, is widely applicable to the surface protection and remanufacturing of vulnerable equipment parts in extreme environments, and has important economic value and popularization significance.

[0131] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A corrosion-resistant lightweight high-entropy alloy composite coating, characterized in that: It includes a lightweight high-entropy alloy layer and a transition layer. The lightweight high-entropy alloy layer is disposed on the surface of the transition layer, and the lightweight high-entropy alloy layer and the transition layer are arranged in an interleaved manner; The material of the lightweight high-entropy alloy layer is AlZrNbTiVCr lightweight high-entropy alloy; The material of the transition layer is pure titanium; The AlZrNbTiVCr lightweight high-entropy alloy is a single BCC structure phase; The preparation method of the corrosion-resistant lightweight high-entropy alloy composite coating includes the following steps: S1. Prepare AlZrNbTiVCr lightweight high-entropy alloy powder and pure titanium powder for use; S2. Use directional energy deposition to deposit the pure titanium powder and AlZrNbTiVCr lightweight high-entropy alloy powder on the surface of the substrate in sequence, layer by layer to prepare the coating, and the additive manufacturing direction of the next layer is rotated by a certain angle relative to the previous layer, and the angle range is 45-135°, thus obtaining the corrosion-resistant lightweight high-entropy alloy composite coating; The AlZrNbTiVCr lightweight high-entropy alloy powder described in S1 contains the following elements by mass fraction: 4-6% Al, 6-9% Zr, 20-25% Nb, 40-50% Ti, 12-16% V, 4-6% Cr; The sphericity of the AlZrNbTiVCr lightweight high-entropy alloy powder described in S1 is 90-99%, the particle size distribution range is 45-150μm, Dv(10) is 45-50μm, Dv(50) is 55-75μm, Dv(90) is 90-110μm; The sphericity of the pure titanium powder described in S1 is 90-99%, and the purity is 99.9%; The process parameters of the directional energy deposition described in S2 include: laser power is 2200-3500W, spot diameter is 3-5mm, powder feeding rate is 10-25g / min, laser scanning rate is 6-14mm / s, and the overlapping rate is 30-60%; Before the directional energy deposition described in S2, it also includes the step of induction preheating treatment of the substrate, the preheating temperature is 200-400°C, and the time is 20-40min; The directional energy deposition described in S2 uses Ar and / or He as the shielding gas.

2. The corrosion-resistant lightweight high-entropy alloy composite coating according to claim 1, characterized in that: Both the lightweight high-entropy alloy layer and the transition layer are provided with multiple layers. A single-layer lightweight high-entropy alloy layer is disposed between two adjacent transition layers, and the surface layer of any lightweight high-entropy alloy layer is perpendicular to the intersecting transition layer, and the surface layer of any lightweight high-entropy alloy layer is perpendicular to the intersecting transition layer.

3. The corrosion-resistant lightweight high-entropy alloy composite coating according to claim 2, characterized in that: The composite coating is a four-layer composite coating. The four-layer composite coating includes a first lightweight high-entropy alloy layer, a second transition layer, and a second lightweight high-entropy alloy layer that are stacked in sequence from bottom to top. The first lightweight high-entropy alloy layer is disposed between the first transition layer and the second process layer. The first transition layer is vertically disposed on the lower surface of the first lightweight high-entropy alloy layer; The second transition layer is vertically disposed on the upper surface of the first lightweight high-entropy alloy layer, and the lower surface of the second lightweight high-entropy alloy layer is vertically disposed on the upper surface of the second transition layer.

4. The corrosion-resistant lightweight high-entropy alloy composite coating according to claim 1, characterized in that: The total thickness of the composite coating is 2-3 mm, and the thickness ratio of the lightweight high-entropy alloy layer to the transition layer is (0.5-0.8):(0.6-1).

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