A high-entropy alloy, a high-entropy alloy cladding layer for repairing and a preparation method thereof

Abstract

The application provides a high-entropy alloy, a high-entropy alloy cladding layer for repair and a preparation method thereof, and relates to the technical field of metal additive remanufacturing. 38 Cr6Ni 38 Ti9Al9) 100‑x Ta x wherein 1at.%<=x<=5at.%, the atomic percentage of each element is as follows: Fe: 36.10~37.62at.%, Ni: 36.10~37.62at.%, Cr: 5.70~5.94at.%, Ti: 8.55~8.91at.%, Al: 8.55~8.91at.%, and Ta: 1.00~5.00at.%. The application increases the content of elements Al and Ti in the high-entropy alloy and reduces the content of element Cr, so that the interface bonding strength is ensured. The high-entropy alloy cladding layer has an FCC+BCC dual-phase structure.

Description

Technical Field

[0001] This invention belongs to the field of metal additive remanufacturing technology, specifically relating to a high-entropy alloy, a high-entropy alloy cladding layer for repair, and a method for preparing the same. Background Technology

[0002] Carbon steel flanges, with their excellent mechanical properties, significantly low cost-effectiveness, and wide process adaptability, have become core connection components in marine piping systems, and their performance directly affects the operational safety and service life of the vessel. However, in the harsh marine environment, carbon steel flanges must simultaneously cope with multiple challenges such as seawater corrosion, fluid erosion and wear, and mechanical fatigue. Their insufficient wear resistance and corrosion resistance are becoming increasingly prominent, becoming a key factor restricting the reliability of piping systems. Therefore, developing rapid repair technologies for damaged carbon steel flange components is of great significance for ensuring the long-term safe operation of marine piping systems.

[0003] Laser cladding technology, as a highly efficient additive remanufacturing method, rapidly melts pre-fabricated alloy powder with a high-energy laser beam to form a metallurgically bonded cladding layer on the substrate surface, providing a new approach for repairing damaged carbon steel flanges. In particular, the development of novel high-entropy alloy materials in recent years has brought new opportunities to overcome the bottlenecks of large heat-affected zones and low bonding strength in traditional repair techniques.

[0004] To ensure the stability of the passivation film (cladding layer) in the marine environment, the Cr content in the currently developed high-entropy alloy materials is usually high (atomic percentage > 20%), which makes the microcracks in the cladding layer structure frequent and accompanied by porosity defects, resulting in a decrease in the interfacial bonding strength between the cladding layer and the substrate. Summary of the Invention

[0005] Therefore, the present invention provides a high-entropy alloy, a high-entropy alloy cladding layer for repair, and a method for preparing the same, which can solve the problem of reduced interfacial bonding strength between the cladding layer and the substrate in the prior art.

[0006] To address the aforementioned problems, on one hand, the present invention provides a high-entropy alloy, wherein the chemical formula of the high-entropy alloy, based on atomic percentage, is (Fe 38 Cr6Ni 38 Ti9Al9) 100-x Ta x Where 1 at.% ≤ x ≤ 5 at.%, the atomic percentages of each element are: Fe: 36.10~37.62 at.%, Ni: 36.10~37.62 at.%, Cr: 5.70~5.94 at.%, Ti: 8.55~8.91 at.%, Al: 8.55~8.91 at.%, Ta: 1.00~5.00 at.%.

[0007] On the other hand, the present invention provides a method for preparing a high-entropy alloy cladding layer for repair, wherein a high-entropy alloy powder is clad onto the surface of a substrate using a laser cladding process to form a high-entropy alloy cladding layer; wherein the high-entropy alloy powder is the powder of the aforementioned high-entropy alloy.

[0008] Furthermore, the parameters of the laser cladding process are as follows: laser power of 800~1000W; scanning rate of 8~10mm / s; powder feeding rate of 0.4~0.6r / min; overlap rate of 48~52%; protective gas is Ar gas, with a flow rate of 20~25L / min and a pressure of 0.3~0.5MPa; preferably, the overlap rate is 50%.

[0009] Furthermore, before the laser cladding step, the process further includes drying the high-entropy alloy powder; preferably, the drying temperature is 150-200℃ and the holding time is 1.5-2h.

[0010] Furthermore, the high-entropy alloy powder is prepared by gas atomization; wherein the particle size of the high-entropy alloy powder is 45~150μm.

[0011] Furthermore, the substrate is made of Q235 steel.

[0012] In another aspect, the present invention provides a high-entropy alloy cladding layer for repair, wherein the high-entropy alloy cladding layer is obtained by any of the preparation methods described above; the microstructure of the high-entropy alloy cladding layer includes a dual-phase solid solution structure of FCC and BCC.

[0013] Furthermore, the surface hardness of the high-entropy alloy cladding layer is ≥600 HV; the corrosion current density of the high-entropy alloy cladding layer in a 3.5 wt.% NaCl solution environment is ≤0.04 μA / cm². 2 .

[0014] Furthermore, the high-entropy alloy cladding layer can be metallurgically bonded to the substrate.

[0015] Furthermore, the high-entropy alloy cladding layer is used for the repair of damage to carbon steel; preferably, the high-entropy alloy cladding layer is used for the repair of damage to carbon steel flanges in marine piping systems.

[0016] The high-entropy alloy, the high-entropy alloy cladding layer for repair, and the preparation method provided by this invention have the following beneficial effects:

[0017] 1. In one aspect, the present invention provides a high-entropy alloy, wherein the chemical formula of the high-entropy alloy, by atomic percentage, is (Fe 38 Cr6Ni 38 Ti9Al9) 100-x Ta xWhere 1 at.% ≤ x ≤ 5 at.%, the atomic percentages of each element are: Fe: 36.10~37.62 at.%, Ni: 36.10~37.62 at.%, Cr: 5.70~5.94 at.%, Ti: 8.55~8.91 at.%, Al: 8.55~8.91 at.%, Ta: 1.00~5.00 at.%. This invention reduces the Cr content by increasing the content of Al and Ti in the high-entropy alloy, thus preventing excessive Cr from forming brittle Sigma phases (such as FeCr intermetallic compounds) during the rapid cooling process of laser cladding. This avoids frequent microcracks and accompanying porosity defects in the cladding layer, ensuring interfacial bonding strength. Compared to Cr, Al and Ti are more reactive, preferentially dissolving in corrosive environments, promoting Cr2O3 nucleation, and ensuring the corrosivity of the cladding layer. Specifically, Al "replaces" Cr in the passivation film, causing more Cr to accumulate at the film / substrate interface; Ti... 4+ The introduction of [a substance] can alter the defect structure of oxides, reduce the oxygen diffusion rate, and thus contribute to the stability of Cr2O3.

[0018] 2. Furthermore, compared with existing high-entropy alloys, this invention replaces Co with Ta. On the one hand, the atomic radius of Ta is larger than that of Co, which can induce significant lattice distortion, thereby enhancing the solid solution strengthening effect. On the other hand, it can reduce the preparation cost and avoid the environmental hazards caused by Co leaching.

[0019] 3. On the other hand, this invention provides a method for preparing a high-entropy alloy cladding layer for repair. A laser cladding process is used to clad high-entropy alloy powder onto the surface of a substrate to form a high-entropy alloy cladding layer. The high-entropy alloy powder used is the powder of the aforementioned high-entropy alloy. The parameters of the laser cladding process are: laser power of 800~1000W; scanning rate of 8~10mm / s; powder feeding rate of 0.4~0.6r / min; overlap rate of 50%; protective gas is Ar gas, with a flow rate of 20~25L / min and a pressure of 0.3~0.5MPa. Based on the increased Al, Ti, and Ta elements in the high-entropy alloy powder, the melting point of the high-entropy alloy powder increases. This invention increases the laser power and decreases the scanning rate to increase the molten pool temperature and extend the molten pool time, respectively, thereby ensuring the full dissolution of the high-entropy alloy powder in the molten pool. However, the increased molten pool temperature and extended molten pool time can lead to the volatilization of low-melting-point Al elements.

[0020] This invention develops a novel high-entropy alloy cladding layer material system adapted to laser cladding processes, while ensuring the corrosion resistance and wear resistance of the alloy. The high-entropy alloy cladding layer of this invention is metallurgically bonded to the substrate, exhibiting significantly superior hardness, wear resistance, and corrosion resistance compared to traditional carbon steel materials. It can meet the remanufacturing and repair requirements of damaged components in fields such as carbon steel ships, opening up new directions for the engineering application of high-entropy alloys. Attached Figure Description

[0021] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0022] Figure 1 The image shows the XRD pattern of the high-entropy alloy cladding layer prepared in Example 1 of this invention.

[0023] Figure 2 This is a SEM image of the cross-sectional microstructure of the high-entropy alloy cladding layer prepared in Example 1 of the present invention;

[0024] Figure 3 The polarization curve of the high-entropy alloy cladding layer prepared in Example 1 of the present invention in 3.5 wt.% NaCl solution;

[0025] Figure 4 The XRD pattern of the high-entropy alloy cladding layer prepared in Comparative Example 1;

[0026] Figure 5 Polarization curve of the high-entropy alloy cladding layer prepared in Comparative Example 2 in 3.5 wt.% NaCl solution;

[0027] Figure 6 SEM image of the cross-sectional microstructure of the high-entropy alloy cladding layer prepared in Comparative Example 3;

[0028] Figure 7 This is a magnified SEM image of the high-entropy alloy cladding layer prepared in Comparative Example 3. Detailed Implementation

[0029] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the specific embodiments, structures, features, and effects according to the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "an embodiment" or "an embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0030] To maintain the stability of passivation films in marine environments, currently developed high-entropy alloy material systems are highly dependent on Cr content (atomic percentage > 20%). The applicant has found that excessive Cr readily forms brittle Sigma phases (such as FeCr intermetallic compounds) during the rapid cooling process of laser cladding, leading to frequent microcracks and porosity defects in the cladding layer, thus reducing interfacial bonding strength. Furthermore, while the introduction of Co (typically > 10%) can improve the alloy's wear resistance, its high price (approximately three times that of nickel-based alloys) and potential environmental toxicity limit the large-scale application of high-entropy alloys in the repair field. Therefore, this invention develops a novel high-entropy alloy cladding layer material system adapted to laser cladding processes, while ensuring the alloy's corrosion resistance and wear resistance. The specific scheme is as follows:

[0031] On one hand, the present invention provides a high-entropy alloy, the chemical formula of which, by atomic percentage, is (Fe 38 Cr6Ni 38 Ti9Al9) 100-x Ta x Where 1 at.% ≤ x ≤ 5 at.%, the atomic percentages of each element are: Fe: 36.10~37.62 at.%, Ni: 36.10~37.62 at.%, Cr: 5.70~5.94 at.%, Ti: 8.55~8.91 at.%, Al: 8.55~8.91 at.%, Ta: 1.00~5.00 at.%.

[0032] This invention reduces the Cr content by increasing the Al and Ti content in high-entropy alloys, thus preventing excessive Cr from forming brittle Sigma phases (such as FeCr intermetallic compounds) during the rapid cooling process of laser cladding. This avoids frequent microcracks and accompanying porosity defects in the cladding layer, ensuring interfacial bonding strength. Compared to Cr, Al and Ti are more reactive, preferentially dissolving in corrosive environments and promoting Cr₂O₃ nucleation, ensuring the corrosivity of the cladding layer and maintaining corrosion resistance with low Cr content. Specifically, in terms of corrosion resistance, Al "replaces" Cr in the passivation film, leading to greater Cr enrichment at the film / substrate interface; Ti... 4+ The introduction of Ta alters the defect structure of oxides, reducing the oxygen diffusion rate and thus stabilizing Cr2O3. Furthermore, compared to existing high-entropy alloys, this invention replaces Co with Ta. On one hand, Ta has a larger atomic radius than Co, inducing significant lattice distortion, thereby enhancing the solid solution strengthening effect and compensating for the strength reduction caused by Co deficiency. On the other hand, it reduces preparation costs and avoids the environmental hazards caused by Co leaching.

[0033] The inventors of this invention discovered that the atomic radius of Ta (approximately 143 pm) is significantly larger than that of Fe (124 pm), Ni (124 pm), and Cr (128 pm). Its addition causes strong lattice distortion, resulting in a solid solution strengthening effect. Simultaneously, the addition of Ta promotes the increase of crystal nuclei during alloy solidification, significantly refining the grain size and enhancing printability. Furthermore, Ta is a corrosion-resistant element; Cr+Ta can improve the alloy's resistance to pitting corrosion, compensating for the potential reduction in corrosion resistance under low Cr conditions.

[0034] In terms of strengthening, the atomic radii of Al, Ti, and Ta are significantly larger than those of Ni, Co, and Cr, which can induce significant lattice distortion, thereby enhancing the solid solution strengthening effect. For example, the solid solution strengthening effect of 6 at.% Al added to a NiCoCr alloy is approximately 200 MPa, and that of 2 at.% Ta added is approximately 54 MPa; however, the solid solution strengthening effect produced by co-doping 6 at.% Al and 2 at.% Ta in a NiCoCr alloy reaches as high as 405 MPa, which is clearly greater than the effect of either doping alone. In addition, Ta also has the effect of stabilizing the microstructure and improving corrosion resistance.

[0035] The high-entropy alloy of this invention reduces the Cr content in existing high-entropy alloy systems, effectively mitigating the risk of microstructure deterioration during printing and greatly expanding the adaptability of this alloy system to laser cladding processes. It also ensures the density and printability of the prepared cladding layer. The high-entropy alloy of this invention has high Al and Ti content. By leveraging the preferential dissolution of Al and Ti elements in corrosive environments to promote the nucleation rate of Cr2O3, it promotes the stable formation of dense Cr2O3 with low Cr content, ensuring the corrosion resistance of the cladding layer.

[0036] Patent document CN116479302A discloses a Fe-Cr-Ni-Co-Ti-Al high-entropy alloy with high corrosion resistance and strong plasticity, whose chemical formula is (Fe 33 Cr 36 Ni 15 Co 15 Ti1)100 1-x Al x The Al content specified in this application differs from the Al content range (Al: 8.55~8.91 at.%) in the high-entropy alloy of this invention. Its maximum Al content is 7.5 at. Furthermore, when it exceeds 7 at.%, a Sigma phase will form in the alloy, and it will no longer be a two-phase structure. In contrast, the minimum Al content in this application is 8.55 at. It can form both FCC and BCC two-phase structures.

[0037] Furthermore, in patent document CN116479302A, the high corrosion resistance of the high-entropy alloy mainly stems from the high Cr content and low Ti content, rather than the high Al / Ti content. This is because a high Cr content can spontaneously form a good dense oxide film, requiring a reduction in Ti to ensure the density of the oxide film. However, the alloy of this invention has a low Cr content and cannot spontaneously form a dense oxide film. In this case, the invention takes the opposite approach, significantly increasing the Ti content in the alloy to promote the rapid nucleation of a limited amount of Cr elements by promoting the formation of Ti and Al oxides. The roles of microstructure regulating elements Ti and Ta differ in different alloys. For example, patent document CN118756135A discloses an AlCoCrFeNi-based dual-phase carbide-reinforced laser cladding high-entropy alloy composite coating, where the purpose of introducing Ti and Ta is to form carbides. In contrast, the Ti and Ta introduced in the high-entropy alloy of this invention are dissolved in the matrix and do not form other phases, aiming to ensure the forming quality of the high-entropy alloy during printing.

[0038] Based on the aforementioned high-entropy alloy forming a dual-phase microstructure of FCC and BCC, synergistic strength and toughness are ensured. Simultaneously, the high Al / Ti content promotes the formation of a Cr2O3 film, guaranteeing corrosion resistance. Therefore, it can be used as a high-entropy alloy cladding layer for repair purposes.

[0039] On the other hand, the present invention provides a method for preparing a high-entropy alloy cladding layer for repair, wherein a high-entropy alloy powder is clad onto the surface of a substrate using a laser cladding process to form a high-entropy alloy cladding layer; wherein the high-entropy alloy powder is the powder of the aforementioned high-entropy alloy.

[0040] Generally, the content of Al and Ti should be less than 5 at%, otherwise Al- or Ti-rich intermetallic phases tend to form in the alloy, reducing corrosion resistance. In this application, the content of Al and Ti is increased to more than 5 at%, mainly by using laser cladding technology. Based on its unique rapid cooling rate characteristics, it can effectively suppress the formation of intermetallic phases and broaden the allowable content of Al and Ti.

[0041] Furthermore, the parameters of the laser cladding process are as follows: laser power is 800~1000W; scanning rate is 8~10mm / s; powder feeding rate is 0.4~0.6r / min; overlap rate is 48~52%, preferably 50%; the protective gas is Ar gas, the flow rate of the protective gas is 20~25L / min, and the pressure is 0.3~0.5MPa.

[0042] In the high-entropy alloy of this application, the Ti content is 8.55~8.91 at.%. Ti has an extremely high affinity for oxygen. During laser cladding, if the powder feed rate is too high, the contact time between the powder and the protective gas / ambient atmosphere in the flight path is prolonged, making Ti element prone to preferential oxidation, forming TiO2 inclusions, and reducing the purity of the cladding layer. Therefore, this application selects a low powder feed rate and uses a protective gas with dual limits on pressure and flow rate to reduce the oxidation of active Ti.

[0043] Based on the increase in Al, Ti, and Ta elements in the high-entropy alloy powder, the melting point of the high-entropy alloy powder increases. To achieve corrosion resistance and strength maintenance, this invention increases the laser power and decreases the scanning rate to increase the molten pool temperature and extend the molten pool time, respectively, thereby ensuring the full dissolution of the high-entropy alloy powder in the molten pool. However, these two parameters need to be matched; mismatch will lead to the volatilization of low-melting-point Al elements, failing to achieve the purpose of this invention. Furthermore, before the laser cladding step, the invention includes: placing the high-entropy alloy powder in a drying oven for drying. Preferably, the drying temperature is 150-200℃, and the holding time is 1.5-2 hours. For the high-entropy alloy powder of this application, the drying temperature and holding time are lower than the oxidation initiation temperature of active elements (such as Ti and Al), prevent the formation of an inert oxide layer that hinders element diffusion, and ensure that the internal moisture of the powder completely migrates to the surface and evaporates, thus ensuring the fluidity of the powder during the laser cladding process. The ultimate goal is to ensure the forming quality.

[0044] Furthermore, the high-entropy alloy powder was prepared by gas atomization of a pre-fabricated FeCrNiTiAlTa high-entropy alloy ingot. The particle size of the high-entropy alloy powder was 45–150 μm; the pre-fabricated FeCrNiTiAlTa high-entropy alloy ingot was obtained through vacuum arc melting.

[0045] Preferably, the high-entropy alloy powder is obtained by vacuum inert gas atomization granulation of a pre-formed FeCrNiTiAlTa high-entropy alloy. Pre-formation refers to melting the alloy into ingots using a vacuum electric arc before atomization.

[0046] On the one hand, the rapid solidification characteristics of gas atomization can overcome casting defects caused by the "delayed diffusion" of high-entropy alloys and achieve uniform element distribution. On the other hand, the high sphericity, low oxygen content, and suitable particle size distribution of the atomized powder make it suitable for the laser cladding process parameters of "low powder feeding rate + pressure / flow rate dual-limited protective gas" defined in this invention, ensuring the high density and low defect rate of the cladding layer.

[0047] Furthermore, the substrate is made of Q235 steel. This material is the same as that used for carbon steel flanges. Preferably, before the laser cladding step, the substrate is sequentially subjected to ultrasonic cleaning, pickling, and drying to obtain a pretreated substrate material. The pretreatment, including cleaning, is to ensure good bonding performance between the high-entropy alloy and the substrate during laser cladding and to avoid the introduction of impurities. In addition, the introduction of Ta element in this application can suppress the diffusion of Fe element in Q235 steel, thereby reducing the dilution rate at the interface, avoiding the formation of brittle phases, further preventing cracking of the cladding layer, and ensuring the interfacial bonding strength and corrosion resistance of the cladding layer.

[0048] In this application, the dried high-entropy alloy powder is clad onto the surface of the substrate material using a laser cladding process with synchronous powder feeding to form a high-entropy alloy cladding layer.

[0049] In another aspect, the present invention provides a high-entropy alloy cladding layer for repair, wherein the high-entropy alloy cladding layer is obtained by any of the above preparation methods; the microstructure of the high-entropy alloy cladding layer includes a dual-phase solid solution structure of FCC and BCC, and does not contain a brittle Sigma phase.

[0050] The dominant factor in the formation of the FCC and BCC dual-phase solid solution structure is the alloy composition, and the high-entropy alloy composition of this invention is within the dual-phase stability range. Specifically, the FCC phase exhibits good thermal stability and a low coefficient of thermal expansion, reducing solidification shrinkage stress; the BCC phase possesses a high elastic modulus, resisting thermal stress deformation. Therefore, the FCC and BCC dual-phase microstructure of the high-entropy alloy of this invention is beneficial for synergistically improving crack resistance and thermal stability.

[0051] Furthermore, the surface hardness of the high-entropy alloy cladding layer is ≥600 HV; the corrosion current density of the high-entropy alloy cladding layer in a 3.5 wt.% NaCl solution environment is ≤0.04 μA / cm². 2 .

[0052] Furthermore, the high-entropy alloy cladding layer can be metallurgically bonded to the substrate, indicating a high interfacial bonding strength.

[0053] Furthermore, the high-entropy alloy cladding layer is used for the repair of damage to carbon steel; preferably, the high-entropy alloy cladding layer is used for the repair of damage to carbon steel flanges in marine piping systems.

[0054] The present invention will be further described below with reference to specific embodiments and comparative examples.

[0055] Example 1

[0056] This embodiment provides a method for preparing a high-entropy alloy cladding layer. The high-entropy alloy powder used contains high-entropy alloy powder with atomic percentages of Fe, Cr, Ni, Al, Ti, and Ta of 36.10 at.%, 5.70 at.%, 36.10 at.%, 8.55 at.%, 8.55 at.%, and 5.00 at.%, respectively. The corresponding chemical formula for the high-entropy alloy is (Fe... 38 Cr6Ni 38 Ti9Al9) 95 Ta5 (i.e., x = 5 at.%); specifically, the following steps are included:

[0057] (1) Calculate the required mass of Fe, Cr, Ni, Al, Ti and Ta according to the atomic percentage of each of the above elements; and use vacuum arc melting to form master alloy ingots;

[0058] (2) The master alloy ingot obtained in step (1) is prepared into powder using an inert gas atomization powder preparation system; powder with a particle size of 50-118 μm is selected by sieving for subsequent processing;

[0059] (3) Place the high-entropy alloy powder obtained in step (2) in a drying oven and dry it at a temperature of 200°C for 2 hours to remove moisture and ensure the dryness of the powder.

[0060] (4) Perform ultrasonic cleaning on the surface of the Q235 substrate. The dimensions of the Q235 steel are 200×100×50mm. 3 (That is, the base is 200mm long, 100mm wide, and 50mm high);

[0061] (5) The high-entropy alloy powder obtained in step (3) is clad onto the surface of Q235 steel by laser cladding process and synchronous powder feeding. High-purity argon gas is introduced for protection during the cladding process. The parameters of the laser cladding process are: laser power of 1000W; scanning rate of 8mm / s; powder feeding rate of 0.6r / min; overlap rate of 50%; protective Ar gas flow rate of 25L / min and pressure of 0.3~0.5MPa.

[0062] Figure 1 This is the XRD pattern of the high-entropy alloy cladding layer obtained in this embodiment. Figure 1 It can be seen that the microstructure of the obtained high-entropy alloy cladding layer is an FCC+BCC two-phase solid solution.

[0063] The FCC+BCC dual-phase solid solution microstructure of the resulting high-entropy alloy cladding layer helps reduce hot cracking susceptibility and ensures effective interfacial bonding. The high-entropy alloy cladding layer of this invention utilizes the lattice distortion effect of Ta and the second-phase strengthening characteristics of the dual-phase microstructure to ensure high strength. The formation of a dense and stable high-entropy passivation film through multi-element synergy ensures corrosion resistance.

[0064] Figure 2 This is a SEM image of the cross-sectional microstructure of the high-entropy alloy cladding layer obtained in this embodiment. Figure 2 It can be seen that the high-entropy alloy cladding layer and the Q235 substrate are metallurgically bonded. There is a 2~5μm planar crystal layer at the interface. No defects such as incomplete fusion, pores, voids, or cracks were observed at the interface, and the interface bonding rate is 100%.

[0065] Figure 3 This is a polarization curve of the high-entropy alloy cladding layer prepared in this embodiment in a 3.5 wt.% NaCl solution. Figure 3 It can be seen that the corrosion current density of the obtained high-entropy alloy cladding layer in 3.5 wt.% NaCl solution is 0.032 μA / cm. 2 It exhibits excellent corrosion resistance.

[0066] Example 2

[0067] This embodiment provides a method for preparing a high-entropy alloy cladding layer. The high-entropy alloy powder used contains high-entropy alloy powder with atomic percentages of Fe, Cr, Ni, Al, Ti, and Ta of 36.86 at.%, 5.82 at.%, 36.86 at.%, 8.73 at.%, 8.73 at.%, and 3.00 at.%, respectively. The corresponding chemical formula for the high-entropy alloy is (Fe... 38 Cr6Ni 38 Ti9Al9) 97 Ta3 (i.e., x = 3at.%); specifically, the following steps are included:

[0068] (1) Calculate the required mass of Fe, Cr, Ni, Al, Ti and Ta according to the atomic percentage of each of the above elements; and use vacuum arc melting to form master alloy ingots;

[0069] (2) The master alloy ingot obtained in step (1) is prepared into powder using an inert gas atomization powder preparation system; powder with a particle size of 45-110 μm is selected by sieving for subsequent processing;

[0070] (3) Place the high-entropy alloy powder obtained in step (2) in a drying oven and dry it at a temperature of 200°C for 2 hours to remove moisture and ensure the dryness of the powder.

[0071] (4) Perform ultrasonic cleaning on the surface of the Q235 substrate. The dimensions of the Q235 steel are 200×100×50mm. 3 ;

[0072] (5) The high-entropy alloy powder obtained in step (3) is clad onto the surface of Q235 steel by laser cladding process and synchronous powder feeding. High-purity argon gas is introduced for protection during the cladding process. The parameters of the laser cladding process are: laser power of 900W; scanning rate of 10mm / s; powder feeding rate of 0.5r / min; overlap rate of 50%; protective Ar gas flow rate of 25L / min and pressure of 0.3~0.5MPa.

[0073] Example 3

[0074] This embodiment provides a method for preparing a high-entropy alloy cladding layer. The high-entropy alloy powder used contains high-entropy alloy powder with atomic percentages of Fe, Cr, Ni, Al, Ti, and Ta of 37.62 at.%, 5.82 at.%, 37.62 at.%, 8.91 at.%, 8.91 at.%, and 1.00 at.%, respectively. The corresponding chemical formula for the high-entropy alloy is (Fe... 38 Cr6Ni 38 Ti9Al9) 99 Ta1 (i.e., x = 1 at.%); specifically, it includes the following steps:

[0075] (1) Calculate the required mass of Fe, Cr, Ni, Al, Ti and Ta according to the atomic percentage of each of the above elements; and use vacuum arc melting to form master alloy ingots;

[0076] (2) The master alloy ingot obtained in step (1) is prepared into powder using an inert gas atomization powder preparation system; powder with a particle size of 45-150 μm is selected by sieving for subsequent processing;

[0077] (3) Place the high-entropy alloy powder obtained in step (2) in a drying oven and dry it at a temperature of 200°C for 2 hours to remove moisture and ensure the dryness of the powder.

[0078] (4) Perform ultrasonic cleaning on the surface of the Q235 substrate. The dimensions of the Q235 steel are 200×100×50mm. 3 ;

[0079] (5) The high-entropy alloy powder obtained in step (3) is dried and then clad onto the surface of Q235 steel using a laser cladding process with synchronous powder feeding. High-purity argon gas is introduced for protection during the cladding process. The parameters of the laser cladding process are: laser power of 820W; scanning rate of 9mm / s; powder feeding rate of 0.6r / min; overlap rate of 50%; protective Ar gas flow rate of 25L / min and pressure of 0.3~0.5MPa.

[0080] Comparative Example 1

[0081] This comparative example provides a method for preparing a high-entropy alloy cladding layer, which differs from Example 1 in that Ta is not added to the powder, but an equal amount of Co is used; specifically, the atomic percentages of Fe, Cr, Ni, Al, Ti, and Co in the high-entropy alloy powder are 36.10 at.%, 5.70 at.%, 36.10 at.%, 8.55 at.%, 8.55 at.%, and 5.00 at.%, respectively; the method includes the following steps:

[0082] (1) Calculate the required mass of Fe, Cr, Ni, Al, Ti and Co according to the atomic percentage of each of the above elements; and use vacuum arc melting to form master alloy ingots;

[0083] (2) The master alloy ingot obtained in step (1) is prepared into powder using an inert gas atomization powder preparation system; powder with a particle size of 45-150 μm is selected by sieving for subsequent processing;

[0084] (3) Place the high-entropy alloy powder obtained in step (2) in a drying oven and dry it at a temperature of 200°C for 2 hours to remove moisture and ensure the dryness of the powder.

[0085] (4) Perform ultrasonic cleaning on the surface of the Q235 substrate. The dimensions of the Q235 steel are 200×100×50mm. 3 ;

[0086] (5) The high-entropy alloy powder obtained in step (3) is clad onto the surface of Q235 steel by laser cladding process and synchronous powder feeding. High-purity argon gas is introduced for protection during the cladding process. The parameters of the laser cladding process are: laser power of 1000W; scanning rate of 8mm / s; powder feeding rate of 0.6r / min; overlap rate of 50%; protective Ar gas flow rate of 25L / min and pressure of 0.3~0.5MPa.

[0087] Comparative Example 2

[0088] This comparative example provides a method for preparing a high-entropy alloy cladding layer, which differs from Example 1 in that the atomic percentage of Cr in the powder is twice that of Example 1, while the contents of Al and Ti are reduced. Specifically, the atomic percentages of Fe, Cr, Ni, Al, Ti, and Ta in the high-entropy alloy powder used are 36.10 at.%, 11.4 at.%, 36.10 at.%, 5.6 at.%, 5.6 at.%, and 5.00 at.%, respectively. The method includes the following steps:

[0089] (1) Calculate the required mass of Fe, Cr, Ni, Al, Ti and Ta according to the atomic percentage of each of the above elements; and use vacuum arc melting to form master alloy ingots;

[0090] (2) The master alloy ingot obtained in step (1) is prepared into powder using an inert gas atomization powder preparation system; powder with a particle size of 45-150 μm is selected by sieving for subsequent processing;

[0091] (3) Place the high-entropy alloy powder obtained in step (2) in a drying oven and dry it at a temperature of 200°C for 2 hours to remove moisture and ensure the dryness of the powder.

[0092] (4) Perform ultrasonic cleaning on the surface of the Q235 substrate. The dimensions of the Q235 steel are 200×100×50mm. 3 ;

[0093] (5) The high-entropy alloy powder obtained in step (3) is clad onto the surface of Q235 steel by laser cladding process and synchronous powder feeding. High-purity argon gas is introduced for protection during the cladding process. The parameters of the laser cladding process are: laser power of 1000W; scanning rate of 8mm / s; powder feeding rate of 0.6r / min; overlap rate of 50%; protective Ar gas flow rate of 25L / min and pressure of 0.3~0.5MPa.

[0094] The high-entropy alloy cladding layers prepared in Examples 1-3 and Comparative Examples 1 and 2 were subjected to performance testing. The microhardness of the high-entropy alloy cladding layers was measured using a Q10A+ fully automatic Vickers hardness tester. The tribological properties of the coatings were tested using a multi-functional tribological testing machine (UMT-3), with 6mm diameter Al2O3 grinding balls as the friction material, a reciprocating stroke length of 5mm, a load of 10N, and a wear time of 30min. The corrosion resistance of the high-entropy alloy coatings in simulated seawater (3.5wt.% NaCl solution) was evaluated through electrochemical corrosion tests using a Reference600+GAMRY electrochemical workstation with standard three electrodes. The test results are shown in Table 1.

[0095] Table 1 Performance test results of the high-entropy alloy cladding layers prepared in the examples and comparative examples

[0096]

[0097] As can be seen from Table 1, the high-entropy alloy cladding layers prepared in Examples 1-3 of this invention have a hardness ≥600Hv, while also possessing high wear resistance and corrosion resistance. Among them, such as... Figure 4As shown, in Comparative Example 1, after replacing Ta with Co in Example 1, although the microstructure remained FCC+BCC dual-phase, the atomic radius difference changed. The measured hardness decreased by 155 Hv compared to Example 1, while the friction coefficient and wear loss increased by 0.21 and 5.6 mg, respectively. This indicates that Ta, with its large atomic radius, has a higher solid solution strengthening effect than Co, and can significantly improve the hardness and wear resistance of the cladding layer. On the other hand, due to… Figure 5 As shown in Table 1, in Comparative Example 2, the atomic percentage of Cr in Example 1 was increased by 2 times, while the contents of Al and Ti were decreased. The measured corrosion current density increased by 0.011 μA compared to Example 1, indicating that increasing the contents of Al and Ti can improve the density of the Cr-rich oxide film. This means that despite the reduced Cr content in Example 1, its corrosion resistance is still superior to that of the high-entropy alloy cladding layer with high Cr content in Comparative Example 2. Furthermore, the hardness and wear resistance of the high-entropy alloy cladding layer obtained in Comparative Example 2 are significantly lower than those of the high-entropy alloy cladding layer in Example 1. This is mainly because the high Cr content leads to the formation of a brittle Sigma phase.

[0098] Comparative Example 3

[0099] This comparative example provides a method for preparing a high-entropy alloy cladding layer, one difference from Example 1 being the lower laser power in the laser cladding parameters; wherein, the atomic percentages of Fe, Cr, Ni, Al, Ti, and Ta in the high-entropy alloy powder used are 36.10 at.%, 5.70 at.%, 36.10 at.%, 8.55 at.%, 8.55 at.%, and 5.00 at.%, respectively; specifically including the following steps:

[0100] (1) Calculate the required mass of Fe, Cr, Ni, Al, Ti and Ta according to the atomic percentage of each of the above elements; and use vacuum arc melting to form master alloy ingots;

[0101] (2) The master alloy ingot obtained in step (1) is prepared into powder using an inert gas atomization powder preparation system; powder with a particle size of 45-150 μm is selected by sieving for subsequent processing;

[0102] (3) Place the high-entropy alloy powder obtained in step (2) in a drying oven and dry it at a temperature of 200°C for 2 hours to remove moisture and ensure the dryness of the powder.

[0103] (4) Perform ultrasonic cleaning on the surface of the Q235 substrate. The dimensions of the Q235 steel are 200×100×50mm. 3 ;

[0104] (5) The high-entropy alloy powder obtained in step (3) is dried and then clad onto the surface of Q235 steel using a laser cladding process with synchronous powder feeding. High-purity argon gas is introduced for protection during the cladding process. The parameters of the laser cladding process are: laser power of 600W; scanning rate of 6mm / s; powder feeding rate of 0.8r / min; overlap rate of 50%; protective Ar gas flow rate of 25L / min and pressure of 0.3~0.5MPa.

[0105] Figure 6 SEM image of the cross-sectional microstructure of the high-entropy alloy cladding layer prepared in Comparative Example 3. Figure 6 It is evident that the change in process parameters resulted in numerous porosity defects in the high-entropy alloy cladding layer, reflecting poor forming quality. From... Figure 7 The magnified SEM image shows that the low laser power resulted in a small amount of high-entropy alloy powder not being completely melted, which is not conducive to the Al, Ti and Ta elements playing their respective roles, resulting in pore defects in the cladding layer and reducing the interfacial bonding strength.

[0106] It will be readily understood by those skilled in the art that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0107] 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 protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. A high-entropy alloy, characterized in that, The chemical formula of the high-entropy alloy, by atomic percentage, is (Fe 38 Cr6Ni 38 Ti9Al9) 100-x Ta x Where 1 at.% ≤ x ≤ 5 at.%, the atomic percentages of each element are: Fe: 36.10~37.62 at.%, Ni: 36.10~37.62 at.%, Cr: 5.70~5.94 at.%, Ti: 8.55~8.91 at.%, Al: 8.55~8.91 at.%, Ta: 1.00~5.00 at.%.

2. A method for preparing a high-entropy alloy cladding layer for repair, characterized in that, High-entropy alloy powder is clad onto the surface of a substrate using laser cladding technology to form a high-entropy alloy cladding layer; The high-entropy alloy powder used is the high-entropy alloy powder described in claim 1.

3. The method for preparing a high-entropy alloy cladding layer for repair according to claim 2, characterized in that, The parameters of the laser cladding process are as follows: laser power is 800~1000W; scanning rate is 8~10mm / s; powder feeding rate is 0.4~0.6r / min; overlap rate is 48~52%; the protective gas is Ar gas, the flow rate of the protective gas is 20~25L / min, and the pressure is 0.3~0.5MPa; wherein, the overlap rate is 50%.

4. The method for preparing a high-entropy alloy cladding layer for repair according to claim 2, characterized in that, Before the laser cladding step, the process further includes: drying the high-entropy alloy powder; The drying process is carried out at a temperature of 150-200℃ and a holding time of 1.5-2 hours.

5. The method for preparing a high-entropy alloy cladding layer for repair according to claim 2, characterized in that, The high-entropy alloy powder is prepared by gas atomization; wherein the particle size of the high-entropy alloy powder is 45~150μm.

6. The method for preparing a high-entropy alloy cladding layer for repair according to claim 2, characterized in that, The substrate is made of Q235 steel.

7. A high-entropy alloy cladding layer for repair, characterized in that, The high-entropy alloy cladding layer is obtained by the preparation method described in any one of claims 2-6; the microstructure of the high-entropy alloy cladding layer includes a dual-phase solid solution structure of FCC and BCC.

8. The high-entropy alloy cladding layer for repair according to claim 7, characterized in that, The surface hardness of the high-entropy alloy cladding layer is ≥600 HV; the corrosion current density of the high-entropy alloy cladding layer in a 3.5 wt.% NaCl solution environment is ≤0.04 μA / cm². 2 .

9. The high-entropy alloy cladding layer for repair according to claim 7, characterized in that, The high-entropy alloy cladding layer can be metallurgically bonded to the substrate.

10. The high-entropy alloy cladding layer for repair according to claim 7, characterized in that, The high-entropy alloy cladding layer is used for the repair of damage to carbon steel; specifically, the high-entropy alloy cladding layer is used for the repair of damage to carbon steel flanges in marine pipeline systems.

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