Y-microalloyed FeCoNiCrAl-based high-entropy composite coating and its preparation method

Abstract

This invention discloses a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating and its preparation method, belonging to the field of high-entropy alloy coating technology. The method is as follows: Elemental metal powder and Y-source intermediate alloy powder are selected and mechanically alloyed to prepare FeCoNiCrAl-Y high-entropy alloy composite powder; then, a high-pressure cold spraying process is used for coating deposition to obtain a composite coating; the composite coating is then subjected to short-time high-temperature annealing and long-time low-temperature aging treatments to obtain the Y-microalloyed FeCoNiCrAl-based high-entropy composite coating. This invention addresses the problems of easy oxidation and burn-off of Y element, weak interfacial bonding in cold-sprayed coatings, and insufficient strength-plasticity matching in existing high-entropy alloy coating preparations.

Description

Technical Field

[0001] This invention belongs to the field of high-entropy alloy coating technology, specifically relating to a Y microalloyed FeCoNiCrAl-based high-entropy composite coating and its preparation method. Background Technology

[0002] FeCoNiCrAl-based high-entropy alloys (HEAs) have become a research hotspot in the field of high-entropy alloy coatings due to their excellent room-temperature strength-ductility balance and good high-temperature oxidation resistance. By controlling the content of alloying elements, these alloys can form a multiphase structure consisting of face-centered cubic (FCC) and body-centered cubic (BCC) / B2 ordered phases, combining the advantages of a tough matrix and a reinforcing phase, thus possessing significant engineering application value in surface protection. Although researchers have attempted to improve performance through rare-earth microalloying, avoid high-temperature oxidation through cold spraying, and control the microstructure through subsequent heat treatment, FeCoNiCrAl-based high-entropy alloy coatings still face a series of technical bottlenecks in practical engineering applications.

[0003] First, the precise control of rare earth element microalloying is crucial. Studies have shown that the addition of trace amounts of rare earth elements (such as Y, La, and Ce) can significantly refine grains, purify grain boundaries, and improve oxide film adhesion, making it an effective way to improve the overall performance of high-entropy alloys. However, Y is chemically extremely reactive and has a strong affinity for oxygen. In traditional thermal spraying processes (such as atmospheric plasma spraying, laser cladding, and supersonic flame spraying), the powder needs to undergo a high-temperature melting or semi-melting process, during which Y is easily oxidized and burned off, resulting in the actual Y content in the final coating being far lower than the nominal composition, or even completely lost. Even if some Y is retained, it often agglomerates at grain boundaries in the form of coarse, irregular Y₂O₃ inclusions, which not only fail to exert the expected microalloying effect but also become crack sources, severely damaging the mechanical properties and high-temperature service life of the coating. Therefore, how to achieve precise, uniform, and controllable addition of Y during coating preparation is a key technical challenge restricting the development of Y-microalloyed high-entropy alloy coatings.

[0004] Secondly, there are interfacial bonding defects in cold spray coatings. Atmospheric cold spray, as a low-temperature solid-state deposition technology, utilizes high-pressure gas to accelerate powder particles to supersonic speeds. The particles undergo intense plastic deformation through high-speed impact at temperatures far below the material's melting point, achieving deposition. This effectively avoids problems such as high-temperature oxidation, phase transformation, and burn-off, providing an ideal technical path for preparing oxygen-sensitive active alloy coatings. However, the deposition mechanism of cold spray coatings determines their inherent defects: the bonding between particles within the coating relies on mechanical interlocking and localized adiabatic shear instability. Numerous micropores and weak bonding interfaces exist at the particle interfaces, resulting in limited metallurgical bonding. Simultaneously, the intense work hardening and residual stress introduced by the high-speed impact process, while beneficial for improving surface hardness, significantly reduce the coating's intrinsic plasticity and cohesive strength. This weak interfacial structure is highly susceptible to brittle fracture along the particle interfaces under tensile, bending, or thermal cycling loads, severely restricting the engineering application of cold spray coatings in load-bearing structural components.

[0005] Secondly, there is a contradiction between strength and ductility in the microstructure control of FeCoNiCrAl alloys. The mechanical properties of FeCoNiCrAl-based high-entropy alloys are highly dependent on the precise control of their microstructure. Traditional heat treatment processes face the following problems: although high-temperature annealing can eliminate residual stress introduced by cold spraying and promote interfacial diffusion, it easily leads to grain coarsening, excessive growth of the B2 strengthening phase, and even continuous precipitation of brittle σ phase or Cr-rich phase along grain boundaries, causing severe "precipitation embrittlement" and a sharp decrease in coating toughness; while simple low-temperature treatment cannot effectively eliminate the weak bonding at the particle interface, making it difficult to fully utilize the coating's strength and toughness. How to eliminate the inherent defects of cold-sprayed coatings while achieving precise control of the matrix phase structure and precipitate distribution, and resolving the contradiction between strength and toughness, is the key to the engineering application of this type of coating.

[0006] Furthermore, high-temperature oxidation resistance and thermal cycling stability are insufficient. Although FeCoNiCrAl-based high-entropy alloys can form a dense Al2O3 protective film due to the presence of Al, under high-temperature cyclic oxidation conditions, the traditional Al2O3 film at the substrate interface is prone to peeling due to pore aggregation and impurity segregation, leading to the failure of the coating's protective function. Especially for coatings intended for use in high-temperature thermal cycling conditions such as those in aero-engine hot-end components and gas turbine blades, the long-term adhesion stability of the oxide film is a key factor determining its service life. Current technologies lack a systematic solution for synergistically improving oxide film adhesion through trace element regulation and interface structure design.

[0007] In summary, current technologies for preparing Y-microalloyed FeCoNiCrAl-based high-entropy alloy coatings lack a systematic approach that simultaneously addresses precise Y element addition, cold spray interface strengthening, controllable microstructure regulation, and synergistic high-temperature oxidation resistance. Therefore, developing a Y-microalloyed FeCoNiCrAl-based high-entropy alloy coating and its preparation method that overcomes these technical bottlenecks has significant engineering application value. Summary of the Invention

[0008] To overcome the shortcomings of the prior art, the present invention aims to provide a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating and its preparation method, thereby obtaining a high-performance high-entropy alloy coating suitable for surface protection under extreme working conditions. This addresses four core technical challenges in Y-microalloyed FeCoNiCrAl-based high-entropy alloy coatings: first, the problem of easy oxidation and burn-off of Y element due to its active chemical properties in traditional thermal spraying high-temperature processes, making precise addition difficult; second, the process defects of weak particle interface bonding, limited metallurgical bonding, and low cohesive strength in atmospheric cold spray coatings due to limitations in deposition mechanisms; third, the contradiction between strength and plasticity in FeCoNiCrAl alloys during heat treatment, making synergistic improvement difficult; and fourth, the high-temperature service bottleneck of easy peeling of the Al2O3 protective film and insufficient thermal cycling stability under high-temperature cyclic oxidation conditions.

[0009] To achieve the above objectives, the present invention employs the following technical solution: This invention provides a method for preparing a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating, comprising the following steps: FeCoNiCrAl-Y high-entropy alloy composite powder was prepared by mechanically alloying elemental metal powder and Y source intermediate alloy powder under inert atmosphere protection. FeCoNiCrAl-Y high-entropy alloy composite powder was used as the raw material powder, and a coating was deposited by high-pressure cold spraying process to obtain FeCoNiCrAl-Y high-entropy alloy composite coating. In the high-pressure cold spraying process, the gas pressure is 5-10 MPa and the gas temperature is 500-1000 ℃. The FeCoNiCrAl-Y high-entropy alloy composite coating was subjected to short-time high-temperature annealing and long-time low-temperature aging treatment in sequence to obtain Y micro-alloyed FeCoNiCrAl-based high-entropy composite coating. In the short-time high-temperature annealing treatment, the temperature is 800-1050 ℃ and the time is 1-2 h; in the long-time low-temperature aging treatment, the temperature is 600-800 ℃ and the time is 4-20 h.

[0010] In one embodiment, the elemental metal powder is Fe powder, Co powder, Ni powder, Cr powder, and Al powder; the Y-source master alloy powder is Al-Y master alloy powder, Fe-Y master alloy powder, or Ni-Y master alloy powder.

[0011] In one embodiment, the content of each component in the FeCoNiCrAl-Y high-entropy alloy composite powder, by atomic percentage, is: Fe: 5%-25%, Co: 5%-25%, Ni: 5%-25%, Cr: 5%-25%, Al: 5%-25%, Y: 0.01%-1%.

[0012] In one embodiment, both the elemental metal powder and the Y-source intermediate alloy powder are submicron in size.

[0013] In one embodiment, the inert atmosphere is an Ar atmosphere or an N2 atmosphere; During the mechanical alloying process, the ball-to-material ratio is (10-15):1, the rotation speed is 100-400 rpm, and the time is 5-60h.

[0014] In one embodiment, the FeCoNiCrAl-Y high-entropy alloy composite powder has a particle size of 5-50 μm and a spherical or ellipsoidal morphology.

[0015] In one embodiment, the working gas in the high-pressure cold spraying process is N2 or He, the powder feeding rate is 10-150 g / min, the carrier gas flow rate is 30-100 L / min, the spray gun moving speed is 100-400 mm / s, the spraying distance is 10-30 mm, and the spraying angle is 30-90°.

[0016] In one embodiment, the short-time high-temperature annealing treatment and the long-time low-temperature aging treatment are carried out in a vacuum environment or an inert protective atmosphere; The vacuum level of the vacuum environment is 1.33 × 10⁻⁶. -3 -1.33 Pa; the inert protective atmosphere is an Ar atmosphere or an N2 atmosphere; The cooling method for the short-time high-temperature annealing treatment is furnace cooling or air cooling; The cooling method for the long-term low-temperature aging treatment is air cooling.

[0017] The present invention also provides a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating prepared by the above preparation method, wherein the hardness of the Y-microalloyed FeCoNiCrAl-based high-entropy composite coating is >300 HV and the bonding strength is >20 MPa.

[0018] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for preparing a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating, employing a technical scheme of mechanical alloying powder preparation, high-pressure cold spray deposition, and a two-stage heat treatment. First, mechanical alloying forces the Y element into the alloy powder, obtaining a pre-alloyed powder with uniformly distributed Y elements. Then, combining the low-temperature solid-state deposition characteristics of cold spraying, densification is achieved through solid-state deposition below the material's melting point, preventing oxidation loss and coarsening segregation of Y elements from the source, thus achieving precise microalloying of the active element. Next, a short-time high-temperature annealing treatment causes the Y elements to segregate towards the particle interface, transforming the physical-mechanical interlocking interface of the cold-sprayed coating into a metallurgical bonding interface, eliminating weak bonding defects and residual stress, and significantly improving the coating's cohesive strength and fracture toughness. Based on this, a long-time low-temperature aging treatment precisely induces matrix amplitude modulation decomposition to form an FCC / B2 dual-phase structure, combined with Y-induced nanoscale dispersed precipitates, constructing a multi-scale composite reinforcement network of "FCC matrix, B2 reinforcing phase, and oxide dispersed phase," achieving synergistic optimization of strength and plasticity. Simultaneously, the active element effect of Y significantly improves the interfacial adhesion between the Al2O3 oxide film and the substrate, inhibits interfacial porosity and impurity segregation, and synergistically enhances the high-temperature oxidation resistance and thermal cycling stability of the coating. The resulting Y-microalloyed FeCoNiCrAl-based high-entropy composite coating possesses high bonding strength, excellent strength-plasticity matching, and outstanding high-temperature service performance, demonstrating clear engineering application value in extreme-condition surface protection fields such as hot-end components of aero-engines, gas turbine blades, and marine engineering equipment.

[0019] Furthermore, in the high-pressure cold spraying process used in the above preparation method, the gas pressure is selected as 5-10 MPa and the gas temperature as 500-1000 ℃. This pressure range ensures that the powder particles acquire sufficient kinetic energy to achieve dense deposition through intense plastic deformation, and remains below the material's melting point throughout the process, fundamentally avoiding the oxidation and burning loss of Y element. If the pressure is below 5 MPa or the temperature is below 500 ℃, the powder acceleration is insufficient, the impact energy is inadequate, the coating porosity is high, and the particles are only weakly mechanically interlocked, resulting in extremely low cohesive strength, and even the inability to form a continuous coating. If the pressure is above 10 MPa, the excessively high particle velocity easily erodes the deposited coating, reducing the coating thickness and uniformity, while introducing excessive work hardening and residual stress, significantly increasing the tendency to crack. If the gas temperature is above 1000 ℃, the oxidation of the powder particle surface intensifies, the Y element retention rate decreases, the microalloying effect is lost, and at high temperatures, the powder easily softens and adheres to the inner wall of the nozzle, causing nozzle blockage and compromising process stability.

[0020] Furthermore, in the short-time high-temperature annealing treatment used in the above preparation method, the temperature is set at 800-1050℃ and the time is 1-2 h. This temperature range is sufficient to activate bulk diffusion, drive elements such as Y to segregate towards the particle interface, transform the mechanical interlocking interface of the cold spray into a metallurgical bonding interface, and eliminate residual stress. The short-time heat preservation aims to suppress grain coarsening and precipitation of harmful phases while achieving interface healing. If the temperature is below 800℃ or the time is less than 1 h, atomic diffusion is insufficient, the weak bonding interface is difficult to completely eliminate, residual stress relaxation is insufficient, the improvement of coating cohesive strength and plasticity is limited, and fracture is still likely to occur along the original particle interface. If the temperature is above 1050℃, the matrix grains coarsen rapidly, the B2 strengthening phase grows excessively, and brittle σ phase or Cr-rich phase is easily precipitated continuously along the grain boundaries, causing "precipitation embrittlement" and resulting in a precipitate drop in coating toughness. If the time exceeds 2 h, even if the temperature is suitable, the cumulative thermal effect will still induce grain coarsening and brittle phase precipitation, and the strength-plasticity match will deteriorate.

[0021] Furthermore, in the long-term low-temperature aging treatment used in the above preparation method, the temperature is set to 600-800 ℃ and the time is 4-20 h. This range is the optimal thermodynamic window for the amplitude modulation decomposition of FeCoNiCrAl alloys to form an FCC / B2 dual-phase structure, which can form a uniform and fine amplitude modulation structure and promote the precipitation of Y-induced nano-oxide dispersed phase, constructing a multi-scale strengthening network. If the temperature is below 600 ℃, the amplitude modulation decomposition kinetics are extremely slow, the phase transformation incubation period is long, it is difficult to obtain the ideal volume fraction and amplitude modulation wavelength, and at the same time, Y atom diffusion is suppressed, the nano-dispersed phase cannot be effectively precipitated, and the strengthening contribution is weak; if the time is less than 4 h, the treatment is insufficient, and the synergistic improvement effect on strength and plasticity is not significant. If the temperature is higher than 800 ℃, the thermodynamic driving force of amplitude modulation decomposition weakens or even enters the miscible region, making it impossible to form an ideal amplitude modulation structure. Instead, a coarse equilibrium phase is generated, and the B2 phase and oxide dispersed phases coarsen rapidly, their quantity decreases sharply, and their strength is greatly reduced. If the time exceeds 20 h, the cumulative aging will lead to excessive coarsening of the dispersed phases and may trigger the slow precipitation of brittle phases at grain boundaries, resulting in a severe decrease in plasticity and deviating from the design goal of synergistic strengthening and toughening. Attached Figure Description

[0022] Figure 1 The SEM microstructure of the FeCoNiCrAl-Y high-entropy alloy composite powder prepared in Example 2; Figure 2 The cross-sectional SEM microstructure of the sprayed FeCoNiCrAl-Y high-entropy alloy composite coating prepared in Example 2; Figure 3 The cross-sectional SEM microstructure of the heat-treated FeCoNiCrAl-Y high-entropy alloy composite coating prepared in Example 2; Figure 4The cross-sectional microstructure of the sprayed FeCoNiCrAl-Y high-entropy alloy composite coating prepared for Comparative Example 2 is shown. Figure 1 ; Figure 5 The cross-sectional microstructure of the sprayed FeCoNiCrAl-Y high-entropy alloy composite coating prepared for Comparative Example 2 is shown. Figure 2 ; Figure 6 The image shows the cross-sectional microstructure of the sprayed FeCoNiCrAl-Y high-entropy alloy composite coating prepared for Comparative Example 5. Detailed Implementation

[0023] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions mentioned in the specification are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0024] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0025] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0026] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0027] This invention provides a method for preparing a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating, comprising the following steps: Step 1): According to the atomic percentages Fe: 5%-25%, Co: 5%-25%, Ni: 5%-25%, Cr: 5%-25%, Al: 5%-25%, Y: 0.01%-1%, submicron-scale elemental metal powder and Y source intermediate alloy powder are placed in a ball mill jar and mechanically alloyed under a high-purity inert atmosphere (Ar or N2) to prepare FeCoNiCrAl-Y high-entropy alloy composite powder with a particle size of 5-50 μm, spherical or ellipsoidal morphology and good flowability.

[0028] The elemental metal powders are Fe powder, Co powder, Ni powder, Cr powder, and Al powder. The Y-source master alloy powder is a pre-melted Al-Y master alloy powder, Fe-Y master alloy powder, or Ni-Y master alloy powder, which needs to be crushed and pulverized to a particle size similar to that of the other main elemental metal powders (elemental metal powders). During the mechanical alloying process, a high ball-to-material ratio of 10:1-15:1 is used, the rotation speed is controlled at 100-400 rpm, and ball milling is performed for 5-60 hours.

[0029] Step 2): Using the FeCoNiCrAl-Y high-entropy alloy composite powder obtained in Step 1) as raw material, a high-pressure cold spraying process is used to deposit a coating to obtain a dense FeCoNiCrAl-Y high-entropy alloy composite coating.

[0030] The parameters of the high-pressure cold spraying process are as follows: gas pressure 5-10 MPa, gas temperature 500-1000℃, working gas is N2 or He, powder feeding rate 10-150 g / min, carrier gas flow rate 30-100 L / min, spray gun moving speed 100-400 mm / s, spraying distance 10-30 mm, and spraying angle 30-90°. Preferred parameters for the high-pressure cold spraying process are: gas pressure 7.5-10 MPa, gas temperature 750-1000℃, powder feeding rate 80-150 g / min, carrier gas flow rate 65-100 L / min, spray gun moving speed 100-250 mm / s, spraying distance 10-20 mm, and spraying angle 60-90°.

[0031] Step 3): The FeCoNiCrAl-Y high-entropy alloy composite coating obtained in Step 2) is subjected to short-time high-temperature annealing and long-time low-temperature aging treatment in sequence to obtain a high-performance Y micro-alloyed FeCoNiCrAl-based high-entropy composite coating.

[0032] The short-time high-temperature annealing treatment is carried out at a temperature of 800-1050 ℃ for 1-2 hours, under a vacuum of 1.33 × 10⁻⁶. -3The treatment is carried out under a vacuum environment of -1.33 Pa or an inert atmosphere (Ar or N2), followed by furnace cooling or air cooling. The long-term low-temperature aging treatment is performed at a temperature of 600-800 °C for 4-20 h, also under a vacuum of 1.33 × 10⁻⁶ Pa. -3 The process is carried out under a vacuum environment of -1.33 Pa or under the protection of an inert atmosphere (Ar or N2), and then air-cooled after treatment.

[0033] This invention also provides a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating prepared by the above-described method. The Y-microalloyed FeCoNiCrAl-based high-entropy composite coating has a hardness >300 HV and a bonding strength >20 MPa. Under preferred conditions, the Y-microalloyed FeCoNiCrAl-based high-entropy composite coating has a hardness >620 HV, a bonding strength >75 MPa, and a porosity of 0.35~0.42%.

[0034] In summary, this invention achieves precise micro-alloying by combining mechanical alloying with low-temperature solid-state deposition via high-pressure cold spraying, thus avoiding oxidation and burn-off of Y. Short-time high-temperature annealing utilizes the interfacial segregation and preferential diffusion characteristics of Y to strengthen the interfacial bonding of the cold-sprayed particles. Long-term low-temperature aging treatment induces amplitude modulation decomposition of the matrix, combined with the dispersion strengthening of Y-induced nano-precipitates, achieving excellent strength-plasticity matching and high-temperature oxidation resistance. The resulting coating possesses high bonding strength, excellent strength-plasticity matching, and outstanding high-temperature service capability, making it suitable for surface protection under extreme conditions such as hot-end components of aero-engines, gas turbine blades, and marine engineering equipment.

[0035] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined in this application.

[0036] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0037] In the following embodiments, Embodiments 1, 2, 4, and 5 are preferred embodiments of the present invention, while Embodiments 3 and 6 are examples near the lower boundary of the parameter range, used to illustrate the significance of the critical parameters of the present invention. In Embodiments 3 and 6, the cold spraying process parameters are at the lower limit (pressure 5MPa, temperature 500℃, spraying distance 30mm), and the coating density and bonding strength do not reach ideal levels, thus not representing the effect of the preferred embodiments of the present invention.

[0038] Example 1 This embodiment provides a method for preparing a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating, including the following steps: Step 1): The following atomic percentages were used: Fe: 5%, Co: 25%, Ni: 25%, Cr: 25%, Al: 19.99%, Y: 0.01%. Submicron elemental Fe powder, Co powder, Ni powder, Cr powder, and Al powder were mixed with crushed Ni-Y master alloy powder (particle size similar to the main component powder) and placed in a ball mill jar. Mechanical alloying was performed under high-purity Ar gas protection, using a ball-to-powder ratio of 10:1, a rotation speed of 400 rpm, and ball milling for 5 h to obtain ellipsoidal FeCoNiCrAl-Y high-entropy alloy composite powder with a particle size of 50 μm.

[0039] Step 2): The FeCoNiCrAl-Y high-entropy alloy composite powder obtained in Step 1) is deposited using a high-pressure cold spraying process to obtain a dense FeCoNiCrAl-Y high-entropy alloy composite coating. The parameters of the high-pressure cold spraying process are as follows: N2 gas as the working gas, gas pressure 10 MPa, temperature 1000 ℃, powder feed rate 150 g / min, carrier gas flow rate 100 L / min, spray gun moving speed 100 mm / s, spraying distance 10 mm, and spraying angle 90°.

[0040] Step 3): The FeCoNiCrAl-Y high-entropy alloy composite coating obtained in step 2) is subjected to a vacuum of 1.33 × 10⁻⁶. - 3 Under a vacuum environment of Pa, a short-term high-temperature annealing treatment was first performed at 1050 ℃ for 1 h, followed by furnace cooling; then a long-term low-temperature aging treatment was performed at 800 ℃ for 20 h, followed by air cooling, to obtain a Y microalloyed FeCoNiCrAl-based high-entropy alloy composite coating.

[0041] The properties of the Y-microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in this embodiment are as follows: microhardness of 628 HV, porosity of 0.38%, bonding strength of 81 MPa, and oxidation weight gain of 0.68 mg / cm³. 2 Wear rate 2.3×10 -5 mm 3 / (N·m).

[0042] Example 2 This embodiment provides a method for preparing a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating, including the following steps: Step 1): The following atomic percentages were used: Fe: 20%, Co: 20%, Ni: 20%, Cr: 20%, Al: 19.5%, Y: 0.5%. Submicron elemental Fe powder, Co powder, Ni powder, Cr powder, and Al powder were mixed with crushed and pulverized Al-Y master alloy powder (particle size similar to the main component powder) and placed in a ball mill jar. Mechanical alloying was performed under high-purity N2 gas protection, using a ball-to-particle ratio of 12.5:1, a rotation speed of 250 rpm, and ball milling for 32.5 h to obtain spherical FeCoNiCrAl-Y high-entropy alloy composite powder with a particle size of 27.5 μm. Figure 1 As shown.

[0043] Step 2): The FeCoNiCrAl-Y high-entropy alloy composite powder obtained in Step 1) is deposited using a high-pressure cold spraying process to obtain a dense FeCoNiCrAl-Y high-entropy alloy composite coating, such as... Figure 2 As shown. The parameters of the high-pressure cold spraying process are: He gas as the working gas, gas pressure 7.5 MPa, temperature 750 ℃, powder feeding rate 80 g / min, carrier gas flow rate 65 L / min, spray gun moving speed 250 mm / s, spraying distance 20 mm, and spraying angle 60°.

[0044] Step 3): The FeCoNiCrAl-Y high-entropy alloy composite coating obtained in Step 2) was subjected to a short-term high-temperature annealing treatment at 925 ℃ for 1.5 h under Ar inert atmosphere protection, followed by air cooling; then, it was subjected to a long-term low-temperature aging treatment at 700 ℃ for 12 h, followed by air cooling, to obtain a Y microalloyed FeCoNiCrAl-based high-entropy alloy composite coating, as shown below. Figure 3 As shown.

[0045] The properties of the Y-microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in this embodiment are as follows: microhardness of 725 HV, porosity of 0.35%, bonding strength of 85 MPa, and oxidation weight gain of 0.62 mg / cm³. 2 Wear rate 1.9×10 - 5 mm 3 / (N·m).

[0046] Example 3 This embodiment provides a method for preparing a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating, including the following steps: Step 1): The following atomic percentages were used: Fe: 25%, Co: 25%, Ni: 25%, Cr: 19%, Al: 5%, Y: 1%. Submicron elemental Fe powder, Co powder, Ni powder, Cr powder, Al powder, and Fe-Y master alloy powder (particle size similar to the main element powder) were placed in a ball mill jar. Mechanical alloying was performed under high-purity Ar gas protection, using a ball-to-particle ratio of 15:1, a rotation speed of 100 rpm, and ball milling for 60 h to obtain spherical FeCoNiCrAl-Y high-entropy alloy composite powder with a particle size of 5 μm.

[0047] Step 2): The FeCoNiCrAl-Y high-entropy alloy composite powder obtained in Step 1) is deposited using a high-pressure cold spraying process to obtain a dense FeCoNiCrAl-Y high-entropy alloy composite coating. The parameters of the high-pressure cold spraying process are as follows: N2 gas as the working gas, gas pressure 5 MPa, temperature 500 ℃, powder feed rate 10 g / min, carrier gas flow rate 30 L / min, spray gun moving speed 400 mm / s, spraying distance 30 mm, and spraying angle 30°.

[0048] Step 3): The FeCoNiCrAl-Y high-entropy alloy composite coating obtained in Step 2) was subjected to short-term high-temperature annealing at 800 ℃ for 2 h under N2 inert atmosphere protection, followed by furnace cooling; then subjected to long-term low-temperature aging treatment at 600 ℃ for 4 h, followed by air cooling, to obtain Y microalloyed FeCoNiCrAl-based high-entropy composite coating.

[0049] The properties of the Y-microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in this embodiment are as follows: microhardness of 312 HV, porosity of 4.8%, bonding strength of 28 MPa, and oxidation weight gain of 1.15 mg / cm³. 2 Wear rate 8.5×10 -5 mm 3 / (N·m).

[0050] Example 4 This embodiment provides a method for preparing a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating, including the following steps: Step 1): The following atomic percentages were used: Fe: 23%, Co: 5%, Ni: 25%, Cr: 22%, Al: 24.9%, and Y: 0.1%. Submicron elemental Fe powder, Co powder, Ni powder, Cr powder, and Al powder were mixed with crushed Al-Y master alloy powder (particle size similar to the main component powder) and placed in a ball mill jar. Mechanical alloying was performed under high-purity Ar gas protection, using a ball-to-powder ratio of 10:1, a rotation speed of 400 rpm, and ball milling for 5 h to obtain spherical FeCoNiCrAl-Y high-entropy alloy composite powder with a particle size of 48 μm.

[0051] Step 2): The FeCoNiCrAl-Y high-entropy alloy composite powder obtained in Step 1) was deposited using a high-pressure cold spraying process to obtain a dense FeCoNiCrAl-Y high-entropy alloy composite coating. The parameters of the high-pressure cold spraying process were as follows: He gas was used as the working gas, gas pressure was 7.5 MPa, temperature was 750 ℃, powder feed rate was 80 g / min, carrier gas flow rate was 65 L / min, spray gun moving speed was 250 mm / s, spraying distance was 20 mm, and spraying angle was 60°.

[0052] Step 3): The FeCoNiCrAl-Y high-entropy alloy composite coating obtained in Step 2) was subjected to short-term high-temperature annealing at 800 ℃ for 2 h under a vacuum of 1.33 Pa, followed by furnace cooling; then it was subjected to long-term low-temperature aging treatment at 600 ℃ for 20 h, followed by air cooling, to obtain the Y microalloyed FeCoNiCrAl-based high-entropy composite coating.

[0053] The properties of the Y-microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in this embodiment are as follows: microhardness of 692 HV, porosity of 0.42%, bonding strength of 78 MPa, and oxidation weight gain of 0.41 mg / cm³. 2 Wear rate 2.1×10 - 5 mm 3 / (N·m).

[0054] Example 5 This embodiment provides a method for preparing a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating, including the following steps: Step 1): The following atomic percentages were used: Fe: 25%, Co: 25%, Ni: 5%, Cr: 20%, Al: 24.5%, Y: 0.5%. Submicron elemental Fe powder, Co powder, Ni powder, Cr powder, and Al powder were mixed with crushed Ni-Y master alloy powder (particle size similar to the main component powder) and placed in a ball mill jar. Mechanical alloying was performed under high-purity N2 gas protection, using a ball-to-powder ratio of 15:1, a rotation speed of 100 rpm, and ball milling for 60 h to obtain ellipsoidal FeCoNiCrAl-Y high-entropy alloy composite powder with a particle size of 5 μm.

[0055] Step 2): The FeCoNiCrAl-Y high-entropy alloy composite powder obtained in Step 1) is deposited using a high-pressure cold spraying process to obtain a dense FeCoNiCrAl-Y high-entropy alloy composite coating. The parameters of the high-pressure cold spraying process are as follows: N2 gas as the working gas, gas pressure 10 MPa, temperature 1000 ℃, powder feed rate 150 g / min, carrier gas flow rate 100 L / min, spray gun moving speed 100 mm / s, spraying distance 10 mm, and spraying angle 90°.

[0056] Step 3): The FeCoNiCrAl-Y high-entropy alloy composite coating obtained in step 2) is subjected to a vacuum of 1.33 × 10⁻⁶. - 3 Under a vacuum environment of Pa, a short-term high-temperature annealing treatment was first performed at 1050 °C for 1 h, followed by furnace cooling; then a long-term low-temperature aging treatment was performed at 800 °C for 4 h, followed by air cooling, to obtain a Y microalloyed FeCoNiCrAl-based high-entropy composite coating.

[0057] The properties of the Y-microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in this embodiment are as follows: microhardness of 812 HV, porosity of 0.40%, bonding strength of 75 MPa, and oxidation weight gain of 0.38 mg / cm³. 2 Wear rate 1.6×10 - 5 mm 3 / (N·m).

[0058] Example 6 This embodiment provides a method for preparing a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating, including the following steps: Step 1): The following atomic percentages were used: Fe: 25%, Co: 25%, Ni: 25%, Cr: 5%, Al: 19%, Y: 1%. Submicron elemental Fe powder, Co powder, Ni powder, Cr powder, Al powder, and Fe-Y master alloy powder (particle size similar to the main component powder) were placed in a ball mill jar. Mechanical alloying was performed under high-purity Ar gas protection, using a ball-to-particle ratio of 12.5:1, a rotation speed of 250 rpm, and ball milling for 32.5 h to obtain spherical FeCoNiCrAl-Y high-entropy alloy composite powder with a particle size of 28 μm.

[0059] Step 2): The FeCoNiCrAl-Y high-entropy alloy composite powder obtained in Step 1) is deposited using a high-pressure cold spraying process to obtain a dense FeCoNiCrAl-Y high-entropy alloy composite coating. The parameters of the high-pressure cold spraying process are as follows: N2 gas as the working gas, gas pressure 5 MPa, temperature 500 ℃, powder feed rate 10 g / min, carrier gas flow rate 30 L / min, spray gun moving speed 400 mm / s, spraying distance 30 mm, and spraying angle 30°.

[0060] Step 3): The FeCoNiCrAl-Y high-entropy alloy composite coating obtained in Step 2) was subjected to short-time high-temperature annealing at 925 ℃ for 1.5 h under Ar inert atmosphere protection, followed by air cooling; then subjected to long-time low-temperature aging treatment at 700 ℃ for 12 h, followed by air cooling, to obtain Y microalloyed FeCoNiCrAl-based high-entropy composite coating.

[0061] The properties of the Y-microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in this embodiment are as follows: microhardness of 375 HV, porosity of 5.2%, bonding strength of 24 MPa, and oxidation weight gain of 1.35 mg / cm³. 2 Wear rate 9.2×10 -5 mm 3 / (N·m).

[0062] Comparative Example 1 This comparative example provides a method for preparing Y-microalloyed FeCoNiCrAl-based high-entropy composite coatings using optimized laser cladding process parameters, comprising the following steps: Step 1): Same as Step 1) in Example 2.

[0063] Step 2): Using the FeCoNiCrAl-Y high-entropy alloy composite powder obtained in Step 1) as raw material, a coating was prepared by laser cladding. The laser power was 2 kW, the spot diameter was 4 mm, the scanning speed was 6 mm / s, and the overlap rate was 40%. Cladding deposition was carried out under Ar gas protection to obtain the FeCoNiCrAl-Y high-entropy alloy composite coating.

[0064] Step 3): Same as step 3) in Example 2.

[0065] The properties of the Y-microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in this comparative example are as follows: microhardness of 580 HV, porosity of 0.1%, bonding strength of 45 MPa, and oxidation weight gain of 0.75 mg / cm³. 2 Wear rate 6.0×10 -5 mm 3 / (N·m).

[0066] In this comparative example, laser cladding was used instead of high-pressure cold spraying. The powder underwent a high-temperature melting process. Compared with the Y microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in Example 2, the hardness was reduced, the bonding strength was reduced, and the wear rate was increased. This is because laser cladding caused matrix dilution, compositional changes, coarse grains, high thermal stress, and possible cracking.

[0067] Comparative Example 2 This comparative example provides a method for preparing a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating, including the following steps: Step 1): The following atomic percentages were used to prepare the mixture: Fe: 20%, Co: 20%, Ni: 20%, Cr: 20%, Al: 19.5%, Y: 0.5%. Submicron elemental Fe powder, Co powder, Ni powder, Cr powder, Al powder, and crushed Al-Y master alloy powder (particle size similar to the main component powder) were placed in a V-type mixer and mechanically mixed for 4 hours under Ar gas protection to obtain mechanically mixed FeCoNiCrAl-Y high-entropy alloy powder.

[0068] Step 2): Same as Step 2) of Example 2.

[0069] Step 3): Same as step 3) in Example 2.

[0070] The properties of the Y-microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in this comparative example are as follows: microhardness of 210 HV, porosity of 2.50%, bonding strength of 18 MPa, and oxidation weight gain of 1.8 mg / cm³. 2 Wear rate 15×10 -5 mm 3 / (N·m).

[0071] like Figure 4 and Figure 5As shown, this comparative example uses simple mechanical mixing instead of mechanical alloying to prepare powder. The powder does not undergo the repeated cold welding-fracture process of high-energy ball milling to form high-entropy alloy powder. The difference in accelerated heating performance of different powders during cold spraying results in different plastic deformation capabilities of the deposited particles, thus the sprayed coating has high porosity. Compared with the performance of the Y micro-alloyed FeCoNiCrAl-based high-entropy composite coating prepared in Example 2: the hardness is significantly reduced, the bonding strength is extremely low, and the wear rate is extremely high. This is because it is not alloyed; the powder is only a simple mechanical stacking of elements and does not form a high-entropy solid solution. Heat treatment cannot produce uniform aging strengthening, and the powder particles cannot form a strong bond.

[0072] Comparative Example 3 This comparative example provides a method for preparing a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating, including the following steps: Step 1): Same as Step 1) in Example 2.

[0073] Step 2): Same as Step 2) of Example 2.

[0074] Step 3): The FeCoNiCrAl-Y high-entropy alloy composite coating obtained in step 2) was subjected to short-time high-temperature annealing treatment at 925 ℃ for 1.5 h under Ar inert atmosphere protection, followed by air cooling.

[0075] The properties of the Y-microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in this comparative example are as follows: microhardness of 475 HV, porosity of 0.40%, bonding strength of 82 MPa, and oxidation weight gain of 0.70 mg / cm³. 2 Wear rate 5.2×10 - 5 mm 3 / (N·m).

[0076] This comparative example omits the long-term low-temperature aging treatment. Compared with the Y microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in Example 2, the hardness is reduced, the bonding strength is the same, and the wear rate is increased. This is because without low-temperature aging, the coating structure is a supersaturated solid solution or coarse-grained state after high-temperature annealing. It failed to form an FCC / B2 dual-phase structure through amplitude modulation decomposition and failed to fully analyze the nano-dispersed strengthening phase, thus losing the aging strengthening effect.

[0077] Comparative Example 4 This comparative example provides a method for preparing a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating, including the following steps: Step 1): Same as Step 1) in Example 2.

[0078] Step 2): Same as Step 2) of Example 2.

[0079] Step 3): The FeCoNiCrAl-Y high-entropy alloy composite coating obtained in step 2) was subjected to long-term low-temperature aging treatment under Ar inert atmosphere protection, and held at 700 ℃ for 12 h, followed by air cooling.

[0080] The properties of the Y-microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in this comparative example are as follows: microhardness of 742 HV, porosity of 0.38%, bonding strength of 35 MPa, and oxidation weight gain of 0.65 mg / cm³. 2 Wear rate 1.8×10 - 5 mm 3 / (N·m).

[0081] This comparative example skipped the short-term high-temperature annealing treatment and went directly to the aging stage. Compared with the Y microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in Example 2, its hardness was the same or slightly higher, the bonding strength was significantly reduced, and the wear rate was slightly lower. This is because the lack of high-temperature annealing retained a large amount of residual stress, which easily caused the coating to peel off, resulting in extremely poor adhesion. However, the high-density defects and retained deformed structure made it very hard and brittle, and wear may be brittle spalling.

[0082] Comparative Example 5 The difference from Example 2 is that the gas temperature in step 2) of the high-pressure cold spraying process is 300 ℃, which is lower than the lower limit of 500 ℃.

[0083] The product matrix obtained in this comparative example has only a small amount of loosely attached powder particles remaining on its surface, such as... Figure 6 As shown, a continuous, dense coating cannot be formed, and it peels off easily with slight scratches, making it impossible to conduct conventional hardness, bonding strength, and wear performance tests. The coating has a porosity greater than 10%, rendering it unsuitable for practical applications.

[0084] Comparative Example 6 The difference from Example 2 is that the gas temperature in step 2) of the high-pressure cold spraying process is 1200 ℃, which exceeds the upper limit of 1000 ℃.

[0085] The properties of the Y-microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in this comparative example are as follows: microhardness of 680 HV, porosity of 0.50%, bonding strength of 38 MPa, and wear rate of 3.5 × 10⁻⁶. -5 mm 3 / (N·m).

[0086] Compared with the performance of the Y microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in Example 2, the bonding strength is significantly reduced. This is because the powder particles undergo severe oxidation during flight, resulting in a brittle oxide film on the surface, which greatly hinders the formation of metallurgical bonding between the particles.

[0087] Comparative Example 7 The difference from Example 2 is that the high-temperature short-time annealing temperature in step 3) is 1150 ℃, which exceeds the upper limit of 1050 ℃.

[0088] The properties of the Y-microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in this comparative example are as follows: microhardness of 430 HV, porosity of 0.35%, bonding strength of 75 MPa, and wear rate of 5.8 × 10⁻⁶. -5 mm 3 / (N·m).

[0089] Compared with the performance of the Y microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in Example 2, the hardness was significantly reduced, while the bonding strength was still acceptable. This was because the annealing temperature was too high, which caused the grains to coarsen rapidly, ultimately leading to the overall deterioration of the coating performance.

[0090] Comparative Example 8 The difference from Example 2 is that the high-temperature short-time annealing temperature in step 3) is 700 °C, which is lower than the lower limit of 800 °C.

[0091] The properties of the Y-microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in this comparative example are as follows: microhardness of 780 HV, porosity of 0.36%, bonding strength of 40 MPa, and wear rate of 1.8 × 10⁻⁶. -5 mm 3 / (N·m).

[0092] Compared with the performance of the Y microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in Example 2: the hardness is higher, the bonding strength is significantly reduced, the plasticity and toughness are extremely poor, the temperature can only release stress slightly and cannot complete recrystallization, the coating structure is brittle and hard and the residual stress is high, which easily leads to bonding interface failure.

[0093] Comparative Example 9 The difference from Example 2 is that the high-temperature short-time annealing time in step 3) is 5 hours, which exceeds the upper limit of 2 hours.

[0094] The properties of the Y-microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in this comparative example are as follows: microhardness of 510 HV, porosity of 0.35%, bonding strength of 80 MPa, and wear rate of 4.5 × 10⁻⁶. -5 mm 3 / (N·m).

[0095] Compared with the performance of the Y microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in Example 2, the hardness is reduced and the bonding strength is good. This is because the annealing time is too long, which causes grain growth and over-aging, resulting in a decrease in coating strength, but the composition distribution is more uniform.

[0096] Comparative Example 10 The difference from Example 2 is that the high-temperature short-time annealing time in step 3) is 0.5 h, which is less than the lower limit of 1 h.

[0097] The properties of the Y-microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in this comparative example are as follows: microhardness of 740 HV, porosity of 0.36%, bonding strength of 45 MPa, and wear rate of 1.9 × 10⁻⁶. -5 mm 3 / (N·m).

[0098] The overall performance is similar to Comparative Example 4, falling between Comparative Example 4 and Example 2. The hardness is high, but the bonding strength is low, due to the short annealing time, incomplete recrystallization, and insufficient release of residual stress.

[0099] Comparative Example 11 The difference from Example 2 is that the low-temperature long-term aging temperature in step 3) is 900 ℃, which exceeds the upper limit of 800 ℃.

[0100] The properties of the Y-microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in this comparative example are as follows: microhardness of 380 HV, porosity of 0.35%, bonding strength of 80 MPa, and wear rate of 6.8 × 10⁻⁶. -5 mm 3 / (N·m).

[0101] Compared with the performance of the Y microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in Example 2, the hardness is significantly reduced and the plasticity is somewhat restored. This is because the aging temperature enters the phase dissolution range, the strengthening phase coarsens, and the coating undergoes severe over-aging.

[0102] Comparative Example 12 The difference from Example 2 is that the low-temperature long-term aging temperature in step 3) is 500 ℃, which is lower than the lower limit of 600 ℃.

[0103] The properties of the Y-microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in this comparative example are as follows: microhardness of 560 HV, porosity of 0.35%, bonding strength of 82 MPa, and wear rate of 3.8 × 10⁻⁶. -5 mm 3 / (N·m).

[0104] Compared with the performance of the Y microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in Example 2, the hardness is lower. This is because the aging temperature is low, the atomic diffusion is slow, the coating is in a significantly under-aged state, and the strengthening phase is difficult to fully nucleate and grow.

[0105] Comparative Example 13 The difference from Example 2 is that the low-temperature long-term aging time in step 3) is 50 h, which exceeds the upper limit of 20 h.

[0106] The properties of the Y-microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in this comparative example are as follows: microhardness of 610 HV, porosity of 0.35%, bonding strength of 83 MPa, and wear rate of 3.2 × 10⁻⁶. -5 mm 3 / (N·m).

[0107] Compared with the performance of the Y microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in Example 2, the hardness is reduced and the plasticity is improved. This is because the coating has undergone over-aging, the precipitated phase is severely coarsened, and thus the strength is reduced.

[0108] Comparative Example 14 The difference from Example 2 is that the low-temperature long-term aging time in step 3) is 2 hours, which is less than the lower limit of 4 hours.

[0109] The properties of the Y-microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in this comparative example are as follows: microhardness of 655 HV, porosity of 0.35%, bonding strength of 84 MPa, and wear rate of 2.5 × 10⁻⁶. -5 mm 3 / (N·m).

[0110] Compared with the performance of the Y microalloyed FeCoNiCrAl-based high-entropy composite coating prepared in Example 2, the hardness is lower. This is because the aging time is too short, the coating is in an under-aged state, and the peak strengthening effect is not achieved.

[0111] This invention addresses the challenge of synergistically achieving compositional uniformity, metastable structure retention, and performance enhancement in traditional high-entropy alloy coating preparation. It provides a comprehensive method for preparing Y-microalloyed FeCoNiCrAl-based high-entropy coatings, integrating material design, preparation, and performance control. Firstly, in terms of material design, this invention combines Y microalloying with solid-state synthesis of pre-alloyed powders. Using Al-Y, Fe-Y, or Ni-Y master alloys as the Y source, high-energy mechanical alloying is performed with Fe, Co, Ni, Cr, and Al elemental metal powders. The entire process avoids melting, preventing high-temperature burn-off and component segregation of Y elements. This achieves atomic-level uniform mixing of multiple principal elements, including highly reactive Y, and simultaneously constructs an amorphous / nanocrystalline composite metastable structure and an in-situ generated nanoscale Y-Al-O oxide dispersion phase. This integrated "structure-composition-function" powder design fundamentally solves the problem of rare earth element failure due to high-temperature burn-off and segregation, providing the coating with a precursor powder that combines high interfacial energy, high thermal stability, and precise composition. Secondly, in terms of process implementation, this invention employs a synergistic process of metastable powder solid-state deposition (cold spraying) and customized two-step heat treatment. Cold spraying, through low-temperature solid-state deposition, fully preserves the fine metastable characteristics of the precursor powder, solving the problems of component segregation, grain coarsening, and oxide inclusions caused by liquid-phase solidification in traditional thermal spraying, resulting in a dense, ultrafine-grained coating. Furthermore, addressing the issues of high residual stress and insufficient interfacial bonding in the cold-sprayed coating, a two-step heat treatment regime of "high-temperature short-time annealing and low-temperature long-time aging" is designed. This regime is not a direct copy of traditional heat treatment; the high-temperature short-time annealing is used to eliminate residual stress and drive complete metallurgical bonding at the interface; the low-temperature long-time aging relies on the pinning effect of Y element to stabilize the ultrafine-grained matrix and precisely induce high-density nano-coherent precipitates (such as B2 / L12), thereby achieving synergistic strengthening through multiple mechanisms of grain refinement, precipitation strengthening, and dispersion strengthening.

[0112] In summary, this invention organically integrates component microalloying, solid-state synthesis, low-temperature deposition, and phase transformation control to form a complete technical system, solving the core bottlenecks of existing technologies and providing a novel and controllable material solution for preparing high-entropy alloy coatings with exceptional strength, toughness, and thermal stability.

[0113] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A method for preparing a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating, characterized in that, Includes the following steps: FeCoNiCrAl-Y high-entropy alloy composite powder was prepared by mechanically alloying elemental metal powder and Y source intermediate alloy powder under inert atmosphere protection. FeCoNiCrAl-Y high-entropy alloy composite powder was used as the raw material powder, and a coating was deposited by high-pressure cold spraying process to obtain FeCoNiCrAl-Y high-entropy alloy composite coating. In the high-pressure cold spraying process, the gas pressure is 5-10 MPa and the gas temperature is 500-1000 ℃. The FeCoNiCrAl-Y high-entropy alloy composite coating was subjected to short-time high-temperature annealing and long-time low-temperature aging treatment in sequence to obtain Y micro-alloyed FeCoNiCrAl-based high-entropy composite coating. In the short-time high-temperature annealing treatment, the temperature is 800-1050 ℃ and the time is 1-2 h; in the long-time low-temperature aging treatment, the temperature is 600-800 ℃ and the time is 4-20 h.

2. The method for preparing a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating according to claim 1, characterized in that, The elemental metal powder is Fe powder, Co powder, Ni powder, Cr powder, and Al powder; the Y source master alloy powder is Al-Y master alloy powder, Fe-Y master alloy powder, or Ni-Y master alloy powder.

3. The method for preparing a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating according to claim 2, characterized in that, The content of each component in the FeCoNiCrAl-Y high-entropy alloy composite powder, by atomic percentage, is as follows: Fe: 5%-25%, Co: 5%-25%, Ni: 5%-25%, Cr: 5%-25%, Al: 5%-25%, Y: 0.01%-1%.

4. The method for preparing a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating according to claim 1, characterized in that, Both the elemental metal powder and the Y-source intermediate alloy powder are submicron in size.

5. The method for preparing a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating according to claim 1, characterized in that, The inert atmosphere is either an Ar atmosphere or an N2 atmosphere. During the mechanical alloying process, the ball-to-material ratio is (10-15):1, the rotation speed is 100-400 rpm, and the time is 5-60 h.

6. The method for preparing a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating according to claim 1, characterized in that, The FeCoNiCrAl-Y high-entropy alloy composite powder has a particle size of 5-50 μm and a spherical or ellipsoidal morphology.

7. The method for preparing a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating according to claim 1, characterized in that, In the high-pressure cold spraying process, the working gas is N2 or He, the powder feeding rate is 10-150 g / min, the carrier gas flow rate is 30-100 L / min, the spray gun moving speed is 100-400 mm / s, the spraying distance is 10-30 mm, and the spraying angle is 30-90°.

8. The method for preparing a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating according to claim 1, characterized in that, The short-time high-temperature annealing treatment and the long-time low-temperature aging treatment are carried out in a vacuum environment or an inert protective atmosphere; The vacuum level of the vacuum environment is 1.33 × 10⁻⁶. -3 -1.33 Pa; the inert protective atmosphere is an Ar atmosphere or an N2 atmosphere; The cooling method for the short-time high-temperature annealing treatment is furnace cooling or air cooling; The cooling method for the long-term low-temperature aging treatment is air cooling.

9. A Y-microalloyed FeCoNiCrAl-based high-entropy composite coating, characterized in that, The coating was prepared using the method described in any one of claims 1 to 8 for preparing a Y-microalloyed FeCoNiCrAl-based high-entropy composite coating.

10. A Y-microalloyed FeCoNiCrAl-based high-entropy composite coating according to claim 9, characterized in that, The Y-microalloyed FeCoNiCrAl-based high-entropy composite coating has a hardness >300 HV and a bonding strength >20 MPa.

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