Nb-modified AlCrFe2NiCu high-entropy alloy flux-cored wire and preparation method thereof

Abstract

The invention belongs to the technical field of ocean engineering corrosion-resistant materials, and particularly relates to an Nb modified AlCrFe2NiCu high-entropy alloy flux-cored wire and a preparation method thereof, the Nb modified AlCrFe2NiCu high-entropy alloy flux-cored wire is characterized in that the Nb modified AlCrFe2NiCu high-entropy alloy flux-cored wire comprises the following metal components in parts by weight: 6.79-8.69 parts of Al, 13.26-15.85 parts of Cr, 36.02-39.60 parts of Fe, 14.96-17.69 parts of Ni, 16.27-18.17 parts of Cu and 7.46-12.70 parts of Nb, and the purity of all metal powder is 99.9%. Compared with the prior art, the Nb-modified high-entropy alloy has the beneficial effects that the design of equal molar ratio of the high-entropy alloy is broken through, the composition of Al, Cr, Fe, Ni, Cu and Nb elements in non-equal molar ratio is alloyed to form a solid solution, the Nb-modified high-entropy alloy is provided, and the structure of the Nb-modified high-entropy alloy mainly comprises a solid solution of a body-centered cubic (BCC) structure and a small amount of face-centered cubic (FCC) structure, so that the Nb-modified high-entropy alloy can be prepared. And segregation of components and formation of a precipitated phase can be reduced, so that the corrosion resistance is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of corrosion-resistant materials for ocean engineering, and particularly to a Nb-modified AlCrFe2NiCu high-entropy alloy flux-cored wire and a preparation method thereof. Background Art

[0002] The rapid development of ocean engineering has led to the wide application of ocean engineering steel in infrastructure construction such as offshore platforms and subsea pipelines. However, due to the harsh ocean environment, factors such as high salinity, high humidity, strong corrosive media, and complex and variable ocean hydrodynamic forces cause ocean engineering steel to be extremely prone to corrosion, resulting in a decrease in structural strength, local damage, and even overall failure. Traditional remanufacturing and repair technologies have many deficiencies in dealing with the corrosion damage of ocean engineering steel. Ordinary repair materials are difficult to meet the dual requirements of high corrosion resistance and high strength in the ocean environment, resulting in limited durability of the repaired components. Frequent repairs not only cost a lot but also affect the normal operation of ocean engineering. High-entropy alloys, with their unique multi-element mixing characteristics, show great potential in terms of corrosion resistance, wear resistance, etc.

[0003] Chinese Patent Application No. 2018101926369 discloses a method for additive manufacturing of high-entropy alloy double-arc fused wire: the main alloy elements are selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Sc, Pd, Y, Hf, Ta, W, Al or Sn; the secondary alloy elements are selected from C, Si, B, Cr, Sn, Ti, Mo, Cu, V, Zr, Pd, Nb, Co, Y, Re, Hf, Ta, W or Al. The raw materials include alloy strips and flux-cored powder. Among them, the high-entropy alloy includes 5-9 main alloy elements and 0-7 secondary alloy elements, and the atomic percentage content of each main alloy element is 5%-35%, and the atomic percentage content of each secondary alloy element is 0-5%; the flux-cored powder is subjected to drying treatment, sieving treatment and mixing treatment to obtain composite powder, the alloy strip is subjected to cleaning treatment to obtain a cleaned alloy strip, and the cleaned alloy strip and the composite powder are subjected to wire tying and wire drawing treatment to obtain a flux-cored wire with a diameter of 0.8-2.4 mm.

[0004] The Chinese invention patent with the application number 2021106072802 discloses a wear-resistant high-entropy alloy surfacing layer and a preparation method. For the alloy surfacing layer, x is 0.2 or 0.6 or 0.8, y is 0.2 or 0.6 or 0.8, z is 0.2 or 0.6 or 0.8, 4.46 - 8.90 parts of Al element, 9.69 - 17.10 parts of Cr element, 11.20 - 20.85 parts of Cu element, 11.30 - 21.13 parts of Fe element, 11.23 - 19.39 parts of Ni element, 4.93 - 17.18 parts of Mo element, 6.10 - 19.10 parts of Nb element, 3.15 - 9.86 parts of Ti element. The preparation method includes the following steps: Step 1, weigh powders of Al, Cr, Cu, Ni, Mo, Nb, and Ti according to the composition ratio, mix them evenly and dry them; Step 2, add the powders in Step 1 to a flux-cored wire powder feeder, and the powders are sent by a conveyor belt into a U-shaped steel strip and made into a flux-cored wire through multiple passes of rolling and drawing units. In the prior art, the composition of high-entropy alloys mostly adopts an equimolar ratio design, which cannot achieve further breakthroughs in corrosion resistance and is limited in marine engineering applications. Summary of the Invention

[0005] The purpose of the present invention is to provide a Nb-modified AlCrFe2NiCu high-entropy alloy flux-cored wire and a preparation method thereof, overcoming the deficiencies of the prior art, breaking through the equimolar ratio design of high-entropy alloys, with a composition of non-equimolar ratio of Al, Cr, Fe, Ni, Cu, and Nb elements, adopting Nb-modified design to form a solid solution. The alloy forms a body-centered cubic (BCC) structure solid solution and a small amount of face-centered cubic (FCC) structure, improving the corrosion resistance between phases and realizing a wire alloy with various excellent properties such as high hardness, high corrosion resistance, and high wear resistance.

[0006] To achieve the above purpose, the present invention is realized through the following technical solutions:

[0007] Technical solution one: A Nb-modified AlCrFe2NiCu high-entropy alloy flux-cored wire, the metal components are composed according to the weight ratio: 6.79 - 8.69 parts of Al, 13.26 - 15.85 parts of Cr, 36.02 - 39.60 parts of Fe, 14.96 - 17.69 parts of Ni, 16.27 - 18.17 parts of Cu, 7.46 - 12.70 parts of Nb, and the purity of all metal powders is 99.9%.

[0008] Technical solution two: A preparation method of a Nb-modified corrosion-resistant AlCrFe2NiCu high-entropy alloy flux-cored wire, including ball milling and mixing, steel strip preparation, flux-cored filling, and drawing processing. The specific operation steps are as follows:

[0009] 1) Ball milling and mixing: Put all the metal powders in the formula into a ball mill for mixing and ball milling. The ball milling time is 1 - 1.5 hours, the ball-to-material ratio is 10 - 12:1, and the ball milling speed is 200 - 300 revolutions per minute to obtain a uniform cored powder mixture. Put the powder into a drying oven for drying at a temperature of 150 - 200 °C for 3 - 6 hours;

[0010] 2) Steel strip preparation: Select a steel strip as the coating of the cored wire. Its thickness range is 0.1 - 0.3 mm. Pretreat the steel strip, clean, remove rust, and dry it to ensure its surface is clean and free of impurities;

[0011] 3) Cored powder filling: Use a cored wire forming device to fill the dried alloy powder into the steel strip. During the filling process, control the powder feeding rate and filling rate to make the filling rate of the cored wire powder reach 42.6 - 48.2%, ensuring that the cored powder is evenly distributed and stable in the wire blank tube;

[0012] 4) Drawing process: Carry out drawing on the wire blank tube. After a process of six rolling and four drawing steps, gradually draw the wire blank tube into a round shape. During each drawing process, the compression ratio of the wire reduction unit is controlled at 15% - 30%. Finally, draw it into a high-entropy alloy cored wire product with an outer diameter of φ2.45 - 2.65 mm.

[0013] Further, the steel strip is a 304 stainless steel strip.

[0014] Further, the outer diameter of the high-entropy alloy cored wire product is 2.3 - 2.55 mm.

[0015] Further, the preferred filling rate of the cored wire powder is 46.2%.

[0016] Principle of Nb modification in the present invention: The addition of Nb results in the precipitation of new phases, the Laves phase (Fe2Nb) and a small amount of MC phase (NbC). However, the body-centered cubic (BCC) structure still occupies most of the volume. Phase analysis reveals that the Laves phase is distributed in a petal-like shape on the surface of the matrix. The self-corrosion current density of the polarization curve decreases, the self-corrosion potential increases, the corrosion morphology slows down, and the corrosion resistance is improved.

[0017] The composition of the Nb-modified AlCrFe2NiCu high-entropy alloy cored wire in the present invention is AlCrFe2NiCrNb x(x = 0.25, 0.5, 1.0), where the phase composition includes body-centered cubic (BCC), face-centered cubic (FCC), and topological close-packed (Laves) structures. The surfacing layer of the AlCrFe2NiCrNb (x = 0.25, 0.5, 1.0) high-entropy alloy flux-cored wire has a relatively high corrosion potential and a relatively low corrosion rate in the polarization curve in 3.5% NaCl solution, demonstrating excellent corrosion resistance. Among them, the cost of Fe element is relatively low, and increasing its content can reduce the cost of high-entropy alloy in - applications to a certain extent.

[0018] The surfacing technology of flux-cored wire is a rapid and convenient repair process method in manufacturing and remanufacturing technologies. The high-entropy alloy material with certain properties is cladded on the surface of the base material by gas metal arc welding technology, so that the obtained surfacing layer has good metallurgical bonding with the base material. Surfacing or re-repairing on the surface of offshore engineering steel can endow it with a layer of corrosion-resistant alloy, and can also reduce the cost brought by the replacement of key components due to corrosion failure; using this method can be economical and convenient, and at the same time can achieve better metallurgical bonding.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1) The present invention proposes a design concept of corrosion-resistant high-entropy alloy, breaking through the design of equimolar ratio of high-entropy alloy. With the composition of non-equimolar ratio of Al, Cr, Fe, Ni, Cu, and Nb elements, a solid solution is formed through alloying, and the content of low-cost Fe element is increased, which can reduce the application cost of high-entropy alloy;

[0021] 2) The Nb-modified corrosion-resistant AlCrFe2NiCuNbx (x = 0.25, 0.5, 1.0) high-entropy alloy proposed by the present invention has a microstructure mainly composed of a solid solution with a body-centered cubic (BCC) structure and a small amount of a face-centered cubic (FCC) structure. There are obvious differences in corrosion resistance among the phases, reducing the segregation of components and the formation of precipitated phases. These structures provide favorable conditions for the design of corrosion-resistant high-entropy alloys and significantly improve the corrosion resistance of the alloy;

[0022] 3) Through reasonable composition improvement design, the high-entropy alloy of the present invention can obtain a high-entropy alloy surfacing layer with high corrosion resistance. Description of the Drawings

[0023] Figure 1 is a schematic diagram of the preparation process of the flux-cored wire in the embodiment of the present invention;

[0024] Figure 2 is the X-ray diffraction analysis pattern of the corrosion-resistant high-entropy alloy surfacing layer of AlCrFe2NiCu with different Nb element contents in the embodiment of the present invention;

[0025] Figure 3It is the microstructure morphology diagram of the corrosion-resistant high-entropy alloy surfacing layer of AlCrFe2NiCu with different Nb element contents in the embodiments of the present invention: where (a) Nb 0.25 , (b) Nb 0.5 , (c) Nb 1.0 , (d) Nb0;

[0026] Figure 4 It is the polarization curve diagram of the corrosion-resistant high-entropy alloy surfacing layer of AlCrFe2NiCu with different Nb element contents in the embodiments of the present invention;

[0027] Figure 5 It is the comparison diagram of the corrosion morphology of the corrosion-resistant high-entropy alloy surfacing layer of AlCrFe2NiCu with different Nb element contents in the embodiments of the present invention: where (a) 304 stainless steel, (b) Nb0, (c) Nb 0.25 , (d) Nb 0.5 , (e) Nb 1.0 . Specific embodiments

[0028] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with specific embodiments. Obviously, the described embodiments are some embodiments of the present invention, rather than all embodiments.

[0029] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the specific embodiments required for use in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the specific embodiments described below are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other specific embodiments can also be obtained based on these specific embodiments.

[0030] Generally, the components of the embodiments of the present invention described and shown here in the specific embodiments can be arranged and designed in countless different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the specific embodiments is not intended to limit the scope of the claimed present invention, but merely represents the selected embodiments of the present invention.

[0031] Example 1

[0032] A preparation method of a Nb-modified corrosion-resistant AlCrFe2NiCu high-entropy alloy flux-cored wire, including ball milling and mixing, steel strip preparation, flux filling, and drawing processing. The specific operation steps are as follows:

[0033] 1) Ball milling and mixing: Put all the metal powders in the formula (the metal components are composed of 7.78 parts of Al, 14.02 parts of Cr, 38.09 parts of Fe, 15.67 parts of Ni, 17.08 parts of Cu, and 7.46 parts of Nb by weight, and the purity of the metal powders is 99.9%) into a ball mill for ball milling and mixing. The ball milling time is 1 hour, the ball-to-material ratio is 10:1, and the ball milling speed is 200 - 300 revolutions per minute to obtain a uniform flux-cored mixed powder. Then put the powder into a drying oven at a temperature of 150°C for 3 hours of drying;

[0034] 2) Steel strip preparation: Select a steel strip as the coating of the flux-cored wire, with a thickness range of 0.1 - 0.3 mm. Pretreat the steel strip, including cleaning, rust removal, and drying, to ensure its surface is clean and free of impurities;

[0035] 3) Flux-cored filling: Use a flux-cored wire forming device to fill the dried alloy powder into the steel strip. During the filling process, control the powder feeding rate and filling rate to make the filling rate of the flux-cored wire powder reach 46.2%, ensuring the uniform distribution and stability of the flux-cored powder in the wire blank tube;

[0036] 4) Drawing process: Carry out drawing processing on the wire blank tube. Through a process of six rolling and four drawing steps, gradually draw the wire blank tube into a circular shape. The compression ratios of the wire reducing machine set in each drawing process are 28%, 24%, 20%, and 18% respectively, and finally draw it into a high-entropy alloy flux-cored wire product with an outer diameter of φ2.55 mm.

[0037] Example 2

[0038] A preparation method of an Nb-modified corrosion-resistant AlCrFe2NiCu high-entropy alloy flux-cored wire, including ball milling and mixing, steel strip preparation, flux-cored filling, and drawing process. The specific operation steps are as follows:

[0039] 1) Ball milling and mixing: Put all the metal powders in the formula (the metal components are composed of 6.87 parts of Al, 13.42 parts of Cr, 37.68 parts of Fe, 15.34 parts of Ni, 16.57 parts of Cu, and 10.12 parts of Nb by weight, and the purity of the metal powders is 99.9%) into a ball mill for ball milling and mixing. The ball milling time is 1 hour, the ball-to-material ratio is 10:1, and the ball milling speed is 200 - 300 revolutions per minute to obtain a uniform flux-cored mixed powder. Then put the powder into a drying oven at a temperature of 150°C for 3 hours of drying;

[0040] 2) Steel strip preparation: Select a steel strip as the coating of the flux-cored wire, with a thickness range of 0.1 - 0.3 mm. Pretreat the steel strip, including cleaning, rust removal, and drying, to ensure its surface is clean and free of impurities;

[0041] 3) Flux core filling: Use flux cored wire forming equipment to fill the dried alloy powder into the steel strip. During the filling process, control the powder feeding rate and filling rate to make the filling rate of flux cored wire powder reach 42.6%, ensuring that the flux cored powder is evenly distributed and stable in the wire blank tube;

[0042] 4) Drawing process: The welding wire billet tube is drawn. After six rolling and four drawing processes, the welding wire billet tube is gradually drawn into a round shape. The compression ratio of the welding wire diameter reducing unit in each drawing process is 28%, 24%, 20%, and 18% respectively. Finally, it is drawn to a high-entropy alloy flux-cored welding wire product with an outer diameter of φ2.55mm.

[0043] Differences from Example 1: In Example 2, the content of Nb element is increased, and the precipitation of new phases Laves phase (Fe2Nb) and MC phase (NbC) increases. However, the body-centered cubic (BCC) structure still occupies most of the volume. Phase analysis shows that the Laves phase is distributed in blocks on the surface of the substrate. The self-corrosion current density of the polarization curve is the smallest, the self-corrosion potential is the largest, the passivation film on the alloy surface is destroyed, the corrosion is slow, and the corrosion resistance is improved.

[0044] Example 3

[0045] A Nb modified corrosion resistant AlCrFe2NiCuNb 1.0 The preparation method of high entropy alloy flux-cored welding wire includes ball milling mixing, steel strip preparation, flux core filling, and drawing processing. The specific operation steps are as follows:

[0046] 1) Ball milling and mixing: Put all the metal powders in the formula (the metal components are composed of 6.79 parts of Al, 13.26 parts of Cr, 36.02 parts of Fe, 14.96 parts of Ni, 16.27 parts of Cu, and 12.70 parts of Nb in proportion by weight, and the purity of the metal powder is 99.9%) into a ball mill for mixing and ball milling. The ball milling time is 1 hour, the ball-to-material ratio is 10:1, and the ball milling speed is 200-300 rpm to obtain a uniform core mixed powder. The powder is placed in a drying oven at a temperature of 150°C for 3 hours;

[0047] 2) Steel strip preparation: Use steel strip as the coating of flux-cored welding wire, with a thickness range of 0.1-0.3mm. Pre-treat the steel strip by cleaning, derusting and drying to ensure that its surface is clean and free of impurities;

[0048] 3) Flux core filling: Use flux cored wire forming equipment to fill the dried alloy powder into the steel strip. During the filling process, control the powder feeding rate and filling rate to make the filling rate of flux cored wire powder reach 42.6%, ensuring that the flux cored powder is evenly distributed and stable in the wire blank tube;

[0049] 4) Drawing process: The wire blank tube is subjected to a drawing process. After a process of six rolling and four drawing steps, the wire blank tube is gradually drawn into a circular shape. The compression ratios of the wire reducing machine set in each drawing step are 28%, 24%, 20%, and 18% respectively, and finally it is drawn into a high-entropy alloy flux-cored wire product with an outer diameter of φ2.55 mm.

[0050] Differences from Example 2: In Example 3, the content of Nb element increases, resulting in the precipitation of new phases, namely, more Laves phase (Fe2Nb) and MC phase (NbC). However, the body-centered cubic (BCC) structure still occupies most of the volume. Phase analysis shows that the Laves phase is distributed in large chunks on the surface of the matrix. The self-corrosion current density of the polarization curve increases, and the self-corrosion potential decreases. The passivation film on the alloy surface is damaged, the corrosion rate accelerates, and the corrosion resistance deteriorates.

[0051] Comparative Example 1

[0052] A preparation method of an AlCrFe2NiCu high-entropy alloy flux-cored wire includes ball milling and mixing, steel strip preparation, flux core filling, and drawing process. The specific operation steps are as follows:

[0053] 1) Ball milling and mixing: All metal powders in the formula (the metal components are composed of 8.69 parts of Al, 15.85 parts of Cr, 39.60 parts of Fe, 18.10 parts of Ni, and 17.69 parts of Cu by weight, and the purity of the metal powders is 99.9%) are put into a ball mill for mixing and ball milling. The ball milling time is 1 hour, the ball-to-material ratio is 10:1, and the ball milling speed is 200 - 300 revolutions per minute to obtain a uniform flux core mixed powder. The powder is put into a drying oven at a temperature of 150 °C for 3 hours of drying;

[0054] 2) Steel strip preparation: A steel strip is selected as the coating of the flux-cored wire, with a thickness range of 0.1 - 0.3 mm. The steel strip is pretreated, cleaned, rust-removed, and dried to ensure its surface is clean and free of impurities;

[0055] 3) Flux core filling: Using a flux-cored wire forming device, the dried alloy powder is filled into the steel strip. During the filling process, the powder feeding rate and filling rate are controlled to make the filling rate of the flux-cored wire powder reach 42.6%, ensuring the uniform distribution and stability of the flux core powder in the wire blank tube;

[0056] 4) Drawing process: The wire blank tube is subjected to a drawing process. After a process of six rolling and four drawing steps, the wire blank tube is gradually drawn into a circular shape. The compression ratios of the wire reducing machine set in each drawing step are 28%, 24%, 20%, and 18% respectively, and finally it is drawn into a high-entropy alloy flux-cored wire product with an outer diameter of φ2.55 mm.

[0057] Comparative Example 2

[0058] 304 stainless steel of the same size was selected for electrochemical corrosion test in 3.5% NaCl solution. The electrochemical polarization curve in 3.5% NaCl solution is shown in the figure. Figure 4 , which has the highest corrosion current density and the smallest self-corrosion potential; the corrosion morphology is as follows Figure 5 (a), the corrosion morphology is irregular, and many corrosion pits appear.

[0059] The welding samples used in Examples 1-3 and Comparative Examples 1 and 2 use economical and practical low-carbon steel as the base material, and the surface of the low-carbon steel is grinded with an angle grinder to remove surface dirt and rust to prevent defects in the alloy.

[0060] The surfacing process uses an automatic trolley to control the moving position of the welding gun. The arc is used as a heat source to form a good metallurgical bond between the AlCrFe2NiCuNbx high-entropy alloy flux-cored welding wire and the base material. The deposited metal is the prepared high-entropy alloy surfacing layer.

[0061] The shielding gas used in the welding process is argon gas with a purity of 99.9%; the welding process parameters are: welding current of 200A, welding voltage of 28V, welding speed of 10m / h, and gas flow rate of 12L / min.

[0062] Example 1 AlCrFe2NiCuNb 0.25 The corrosion resistance test results of the high entropy alloy cladding layer can be seen in Table 1; the X-ray diffraction analysis diagram is shown in Figure 2 , it can be seen from the figure that AlCrFe2NiCuNb 0.25 High entropy alloys are composed of solid solution phases of body-centered cubic (BCC), face-centered cubic (FCC) and close-packed hexagonal (Laves) structures; their microstructures are as follows: Figure 3 (a), as can be seen from the figure, its microstructure is a typical dendrite structure, with new Laves phase (Fe2Nb) distributed in a petal-like manner on the matrix surface and a small amount of MC phase (NbC) precipitated; the electrochemical polarization curve in 3.5% NaCl melt is as follows Figure 4 , which has a lower self-corrosion current density and a higher self-corrosion potential; its corrosion morphology is as follows Figure 5 (c), corrosion occurs preferentially in the interdendritic region, and corrosion is moderate.

[0063] Example 2: Corrosion-resistant AlCrFe2NiCuNb prepared 0.5 The corrosion resistance test results of the high entropy alloy cladding layer can be seen in Table 1; the X-ray diffraction analysis diagram is shown in Figure 2 , it can be seen from the figure that AlCrFe2NiCuNb 0.25 High entropy alloys are composed of solid solution phases of body-centered cubic (BCC), face-centered cubic (FCC) and close-packed hexagonal (Laves) structures; their microstructures are as follows:Figure 3 (b). As can be seen from the figure, its structure shows a typical dendritic structure, and new Laves phase (Fe2Nb) and a small amount of MC phase (NbC) precipitate on the matrix surface. Among them, the electrochemical polarization curve in 3.5% NaCl solution is as Figure 4 , which has the lowest self-corrosion current density and the highest self-corrosion potential; its corrosion morphology is as Figure 5 (d). Corrosion preferentially occurs in the interdendritic region and the corrosion is relatively slow.

[0064] The corrosion resistance test results of the corrosion-resistant AlCrFe2NiCuNb 1.0 high-entropy alloy surfacing layer can be seen in Table 1; the X-ray diffraction analysis pattern is as Figure 2 . As can be seen from the figure, AlCrFe2NiCuNb 1.0 high-entropy alloy is composed of solid solution phases with body-centered cubic (BCC) structure, face-centered cubic (FCC) structure and close-packed hexagonal (Laves) structure; its microstructure morphology is as Figure 3 (c). As can be seen from the figure, its structure shows a typical dendritic structure, and new Laves phase (Fe2Nb) and a small amount of MC phase (NbC) precipitate on the matrix surface. Among them, the electrochemical polarization curve in 3.5% NaCl solution is as Figure 4 , its corrosion current density increases and the self-corrosion potential decreases; its corrosion morphology is as Figure 5 (d). Obvious corrosion occurs at the grain boundaries and the corrosion resistance deteriorates.

[0065] The corrosion resistance test results of the AlCrFe2NiCu high-entropy alloy surfacing layer obtained in Comparative Example 1 can be seen in Table 1; the X-ray diffraction analysis pattern is as Figure 2 . As can be seen from the figure, the corrosion-resistant AlCrFe2NiCu high-entropy alloy is mainly composed of solid solution phases with body-centered cubic (BCC) structure and face-centered cubic (FCC) structure; its microstructure morphology is as Figure 3 (d). As can be seen from the figure, its structure shows a typical dendritic structure; among them, the electrochemical polarization curve in 3.5% NaCl solution is as Figure 4 , which has a relatively high corrosion current density and a relatively low self-corrosion potential; its corrosion morphology is as Figure 5 (b). Corrosion preferentially occurs in the interdendritic region, and a large amount of corrosion products accumulate on the matrix surface covering the matrix, and the corrosion is relatively severe.

[0066] The corrosion resistance test results of the 304 stainless steel obtained in Comparative Example 2 can be seen in Table 1; among them, the electrochemical polarization curve in 3.5% NaCl solution is as Figure 4 , which has the highest corrosion current density and the smallest self-corrosion potential; the corrosion morphology is as Figure 5 (a). The corrosion morphology is irregular and there are many corrosion pits.

[0067] The comparison results of the corrosion resistance tests of Examples 1-3 and Comparative Examples 1-2 are shown in Table 1.

[0068] Table 1

[0069] Example Type <![CDATA[I corr / mA·cm -2 > <![CDATA[E corr / mV SCE > Example 1 1.39 -400.97 Example 2 0.71 -385.36 Example 3 1.14 -396.42 Comparative Example 1 3.65 -525.5 Comparative Example 2 4.58 -596.42

[0070] As can be seen from Table 1, the corrosion resistance system of the Nb-modified corrosion-resistant AlCrFe2NiCu high-entropy alloy of the present invention consists of a surfacing layer alloy and a NaCl solution. The metal acting as the anode loses electrons and continuously dissolves. Compared with 304 stainless steel, the surfacing alloy has better corrosion resistance. With the continuous addition of the Nb element, the corrosion current decreases, and the corrosion rate of the alloy steadily decreases. In summary, it can be seen that the corrosion resistance is the best when Nb 0.5 is present. Generally speaking, excellent corrosion resistance can be exhibited by a low self-corrosion current density, a wide passivation range, and a "positive" corrosion potential. The self-corrosion current density reflects the corrosion rate of the material. The lower the corrosion current, the smaller the corrosion rate of the material and the more corrosion-resistant it is. The self-corrosion potential is an important means for thermodynamic research. The higher the corrosion potential, the more difficult the corrosion tendency of the material and the more corrosion-resistant it is.

[0071] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A Nb-modified AlCrFe2NiCu high-entropy alloy flux-cored wire, characterized in that, The metal components are composed in terms of parts by weight as follows: 6.79 - 8.69 parts of Al, 13.26 - 15.85 parts of Cr, 36.02 - 39.60 parts of Fe, 14.96 - 17.69 parts of Ni, 16.27 - 18.17 parts of Cu, 7.46 - 12.70 parts of Nb. The purity of all metal powders is 99.9%.

2. The preparation method of a Nb-modified corrosion-resistant AlCrFe2NiCu high-entropy alloy flux-cored wire according to claim 1, characterized in that, It includes ball milling and mixing, steel strip preparation, flux-cored wire filling, and drawing processing. The specific operation steps are as follows: 1) Ball milling and mixing: Put all the metal powders in the formula into a ball mill for mixing and ball milling. The ball milling time is 1 - 1.5 hours, the ball-to-material ratio is 10 - 12:1, and the ball milling speed is 200 - 300 revolutions per minute to obtain a uniform flux-cored mixed powder. Put the powder into a drying oven for drying at a temperature of 150 - 200°C for 3 - 6 hours; 2) Steel strip preparation: Select a steel strip as the coating of the flux-cored wire, with a thickness range of 0.1 - 0.3 mm. Pretreat the steel strip, clean, remove rust, and dry it to ensure its surface is clean and free of impurities; 3) Flux-cored wire filling: Use a flux-cored wire forming device to fill the dried alloy powder into the steel strip. During the filling process, control the powder feeding rate and filling rate to make the filling rate of the flux-cored wire powder reach 42.6 - 48.2%, ensuring the uniform distribution and stability of the flux-cored powder in the wire blank tube; 4) Drawing processing: Perform drawing processing on the wire blank tube. After six rolling and four drawing processes, gradually draw the wire blank tube into a circular shape. During each drawing process, the compression ratio of the wire reducing unit is controlled at 15% - 30%. Finally, draw it into a high-entropy alloy flux-cored wire product with an outer diameter of φ2.45 - 2.65 mm.

3. The preparation method of a Nb-modified corrosion-resistant AlCrFe2NiCu high-entropy alloy flux-cored wire according to claim 2, characterized in that, The steel strip is a 304 stainless steel strip.

4. The preparation method of a Nb-modified corrosion-resistant AlCrFe2NiCu high-entropy alloy flux-cored wire according to claim 2, characterized in that, The outer diameter of the high-entropy alloy flux-cored wire product is 2.3 - 2.55 mm.

5. A Nb-modified corrosion-resistant AlCrFe2NiCu high-entropy alloy flux-cored wire and its preparation method according to claim 2, characterized in that, The filling rate of the flux-cored wire powder is 46.2%.

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