Formula, coating and method of dual in-situ precipitation reinforced FeCoNiCr-based high-entropy alloy composite material with low corrosion-wear synergistic effect

Abstract

The invention discloses a formula, a coating and a method of a dual in-situ precipitation reinforced FeCoNiCr-based high-entropy alloy composite material with a low corrosion-wear synergistic effect. The Al-Co-Cr alloy material comprises the following components in atomic percent: 15 to 30 at% of Al, 10 to 25 at% of Co, 10 to 25 at% of Cr, 10 to 25 at% of Fe, 10 to 25 at% of Ni, 20 to 35 at% of Ti and 5 to 15 at% of C, the preparation method comprises the following steps: filling all metal powder and graphene powder into a ball-milling tank, adding grinding balls, filling argon, sealing, and ball-milling, so as to obtain mixed powder in which the surfaces of metal powder particles are uniformly coated with graphene. The high-entropy alloy composite material with high hardness, high wear resistance and high corrosion resistance is obtained by utilizing the solid solution strengthening effect and the multiple in-situ precipitation strengthening effect of micron-scale TiC and nano-scale precipitation B2. The prepared coating is uniform and compact in structure, is metallurgically bonded with a base material, and has excellent corrosion and friction resistance and low corrosion-wear synergistic effect.

Description

Technical Field

[0001] The present invention relates to a dual in-situ precipitation-reinforced FeCoNiCr-based high-entropy alloy composite material formula with low corrosion-wear synergistic effect, a coating and a preparation method thereof. The coating is applied to corrosion-wear coupling conditions in the fields of marine engineering, shipbuilding engineering, hydraulic engineering, etc. Background Art

[0002] In marine engineering, moving parts such as offshore oil drill pipes, valves, and deep-sea plunger hydraulic pumps are not only exposed to corrosive environments, but also affected by wear loads. Corrosion, wear, and their synergistic effects cause serious material damage to key components, posing a huge threat to marine development activities. In recent years, high-entropy alloy coatings have attracted widespread attention due to their good mechanical properties, corrosion resistance, and wear resistance. Among them, FeCoNiCr high-entropy alloys with a single-phase face-centered cubic structure are one of the most representative alloy systems and have been widely studied in the past decade. This type of high-entropy alloy often has excellent corrosion stability due to its single-phase solid solution structure and is a promising candidate material for marine corrosion. However, its low hardness limits its application as a corrosion-resistant and wear-resistant material. Therefore, how to simultaneously improve the corrosion resistance and wear resistance of FeCoNiCr high-entropy alloy coatings has become a difficulty in the research and development of high-entropy alloys.

[0003] At present, the most commonly used method to strengthen high entropy alloys is to introduce alloying elements such as Mo, Ta, Nb, Zr, etc. into the FeCoNiCr high entropy alloy system to achieve solid solution strengthening or precipitation strengthening. However, these alloying elements have limited improvement in hardness and wear resistance, especially the high cost of adding a large amount of alloying elements, which limits the large-scale application of high entropy alloys in marine engineering.

[0004] Second phase strengthening is another economical and efficient strengthening method. By introducing ceramic particle phases such as WC, TiC, TiB2, Cr3C2, etc. into the high entropy alloy system, the strength, hardness and wear resistance of the high entropy alloy can be greatly improved. However, the lattice matching relationship and wettability between the high entropy alloy matrix and the interface of the added ceramic particle phase are poor, and potential stress concentration may lead to stress corrosion cracking under applied loads. Another problem that cannot be ignored is that there is a potential difference between the carbide second phase and the matrix, leading to the generation of micro-batteries and galvanic corrosion. In particular, the second phase may cause galvanic corrosion and have a potential accelerating effect on wear, resulting in worsening corrosion-wear synergistic damage.

[0005] Therefore, how to reduce the synergistic effect between corrosion and wear of high-entropy alloy composites is an important issue to be solved. Summary of the invention

[0006] In order to solve the problems and defects in the background technology, the invention provides a dual in-situ precipitation enhanced FeCoNiCr-based high entropy alloy composite material formula with low corrosion-wear synergistic effect, coating and preparation method thereof, aiming at the corrosion-wear coupling damage of materials in marine engineering and the high corrosion-wear synergistic effect of conventional high entropy alloys. The composite coating obtained by the invention has uniform and dense structure, metallurgical bonding with the substrate, strong corrosion resistance and low corrosion-wear synergistic effect.

[0007] The technical solution adopted by the present invention is as follows:

[0008] 1. A formula of a dual in-situ precipitation-reinforced FeCoNiCr-based high-entropy alloy composite material with low corrosion-wear synergistic effect:

[0009] Calculated by atomic percentage molar content, it includes Al 15-30at%, Co 10-25at%, Cr 10-25at%, Fe 10-25at%, Ni 10-25at%, Ti 20-35at%, and C 5-15at%.

[0010] The Ti / Al ratio ranges from 1.2 to 2.3: the Ti / C ratio ranges from 1.5 to 5.5.

[0011] 2. A method for preparing a dual in-situ precipitation-reinforced FeCoNiCr-based high entropy alloy composite powder with low corrosion-wear synergistic effect, characterized in that:

[0012] The method is to adopt a low-energy ball milling mixing process to prepare the powder material.

[0013] The method specifically comprises: firstly, according to the material formula of any one of claims 1 to 2, metal powders of Al powder, Co powder, Cr powder, Fe powder, Ni powder and Ti powder and graphene powder are loaded into a stainless steel ball milling jar, and stainless steel grinding balls are added; then, argon protective gas with a purity of 99.99% is filled into the jar, and after sealing, the jar is placed in a drum-type ball mill for ball milling, and after the ball milling is completed, the grinding balls are taken out to obtain a mixed powder in which the graphene is evenly coated on the surface of the metal powder particles.

[0014] In the method, metal powder with a purity of not less than 99.9% and a particle size of 30 to 150 μm and graphene powder with a purity of not less than 95% and a particle size of 0.5 to 1 μm are used as raw materials, stainless steel grinding balls with a diameter of 5 mm are added, and the mass ratio of the stainless steel balls to the raw materials is (0.5 to 2):1.

[0015] In the method, the ball milling mixing is performed for 2 to 5 hours at a rotation speed of 60 to 120 r / min.

[0016] 3. Another method for preparing a dual in-situ precipitation-reinforced FeCoNiCr-based high entropy alloy composite coating with low corrosion-wear synergistic effect:

[0017] The composite material or the composite material powder obtained by the preparation method is used as a raw material and is prepared on the surface of a stainless steel or carbon steel workpiece by adopting an ultra-high-speed laser melting deposition process.

[0018] The ultra-high-speed laser melting deposition process uses a turntable powder feeder and a high-purity argon gas flow with a purity of not less than 99.99% to transport powder to the surface of the workpiece, and uses an ultra-high-speed laser melting deposition device to melt the coaxial powder flow in the air. At the same time, the workpiece substrate is melted to form a molten pool. The molten powder and the workpiece substrate molten pool are combined and then rapidly cooled and solidified, and a metallurgically bonded high-entropy alloy composite coating is formed through multiple overlaps.

[0019] In the ultra-high-speed laser melting deposition process, the powder feeding rate is 10-30 g / min, and the argon pressure of the powder-carrying gas during powder feeding is 0.1-0.4 MPa.

[0020] In the ultra-high-speed laser melting deposition process, the substrate preheating temperature is ≥150°C, the laser power of the laser melting deposition equipment is 1500-4500W, the spot diameter is 2-6mm, the overlap rate is 35-65%, and the scanning line speed is 15-50mm / s.

[0021] The coating thickness is set to 0.5-5 mm. The thickness affects the cracking sensitivity of the coating and needs to be controlled.

[0022] The obtained coating thickness is 0.5~5mm, and the microhardness is ≥680HV 0.2 , the corrosion resistance and corrosion wear resistance are better than those of 2205 duplex stainless steel, and the corrosion-wear synergistic effect is lower than that of thermal sprayed WC-10Co4Co coating.

[0023] The present invention has the following advantages and features:

[0024] (1) The dual in-situ precipitation-reinforced FeCoNiCr-based high-entropy alloy composite material with low corrosion-wear synergistic effect proposed in the present invention belongs to a lightweight high-entropy alloy system and does not contain expensive precious metal elements. Therefore, the overall cost is low and has high application value and prospects.

[0025] (2) In the high entropy alloy composite material formula, Ti and the C element in graphene can synthesize micron-sized TiC ceramic phase in situ, while Al and Ti elements can induce in-situ precipitation of nano-sized B2 phase, forming a dual in-situ precipitation-strengthened high entropy alloy composite coating. Among them, TiC ceramic particles hinder dislocation movement through the Orowan mechanism, significantly improving strength and hardness, while B2 nano-precipitates can effectively prevent dislocation movement through the shear mechanism, thereby improving strength and toughness. The above-mentioned multiple strengthening effects greatly improve the hardness and wear resistance of the FeCoNiCr-based high entropy alloy composite coating.

[0026] (3) The passivation element Ti in the formula can form a dense passivation film, which helps to improve the corrosion resistance of the high entropy alloy. In addition, according to the mixing enthalpy of atomic pairs between each element, the Cr content in the carbide ceramic phase is reduced by Ti, and the degree of Cr depletion in the alloy phase is suppressed, thereby reducing the potential difference between the TiC ceramic particles and the alloy phase. This greatly reduces the galvanic corrosion effect near the ceramic phase interface, thereby reducing the acceleration of corrosion on wear and the corrosion-wear synergy during friction corrosion.

[0027] (4) Low-energy ball milling can make graphene evenly coated on the surface of metal powder particles, which is conducive to the full diffusion of carbon elements and full carbon alloying in the subsequent laser melting process, thereby in situ synthesizing a high-entropy alloy composite coating with uniform distribution of TiC particles.

[0028] (5) The ultra-high-speed laser melting deposition process used has the characteristics of fast cooling and heating, and the higher solidification rate creates conditions for nano-precipitation behavior. At the same time, the coating and the workpiece substrate are completely metallurgically bonded, and the coating is dense and uniform. Compared with conventional laser cladding processes, ultra-high-speed laser melting deposition layers have higher production efficiency, lower dilution rate, finer grains, and better corrosion resistance and wear resistance.

[0029] (6) The solid-solution carbon and TiC reinforcing phase in the high-entropy alloy composite coating can undergo graphitization during the seawater corrosion and friction process to generate a graphite-like carbon film with excellent self-lubricating effect, which can effectively reduce the friction coefficient during the corrosion and friction process and is beneficial to reducing the wear rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The microscopic morphology of the FeCoNiCr-based high entropy alloy composite material mixed powder in Example 2;

[0031] Figure 2 This is a microscopic morphology of the high entropy alloy composite coating deposited by ultra-high speed laser melting in Example 2;

[0032] Figure 3 This is the dual in-situ precipitation strengthening organization diagram of the ultra-high speed laser melting deposition high entropy alloy composite coating in Example 2;

[0033] Figure 4 This is the surface potential distribution diagram of the laser cladding high entropy alloy composite coating in Example 2;

[0034] Figure 5 The microstructure of the laser cladding non-in-situ TiC reinforced high entropy alloy composite coating in the comparative example;

[0035] Figure 6 This is an enlarged microscopic image of the laser cladding ex-situ TiC reinforced high entropy alloy composite coating in the comparative example;

[0036] Figure 7 This is the surface potential distribution diagram of the laser cladding non-in-situ TiC reinforced high entropy alloy composite coating in the comparative example. DETAILED DESCRIPTION

[0037] The present invention will be further described below in conjunction with the accompanying drawings and specific implementations.

[0038] Embodiments of the present invention are as follows:

[0039] Embodiment 1:

[0040] (1) High entropy alloy composite material formulation

[0041] The invention provides a formula of a dual in-situ precipitation-reinforced FeCoNiCr-based high-entropy alloy composite material with low corrosion-wear synergistic effect, which comprises 15at% Al, 10at% Co, 10at% Cr, 10at% Fe, 10at% Ni, 35at% Ti and 10at% C calculated by atomic percentage.

[0042] (2) Preparation method of high entropy alloy composite material powder raw material

[0043] According to the above-mentioned formula, pure metal powder with a purity of not less than 99.9% and a powder particle size of 45 to 105 μm is used as raw material. Al powder, Co powder, Cr powder, Fe powder, Ni powder, Ti powder and graphene powder are mixed and loaded into a stainless steel ball mill, and stainless steel grinding balls with a diameter of 10 mm are added, and the ball-to-material mass ratio is 2:1. Subsequently, high-purity argon protective gas with a purity higher than 99.99% is filled into the tank, and after sealing, it is placed in a drum ball mill for ball milling at 120 r / min and mixed for 5 hours to obtain a composite powder material.

[0044] (3) Preparation method of high entropy alloy composite coating

[0045] Degrease, decontaminate and rust the surface of the workpiece made of 45 steel, and clean it with alcohol or acetone.

[0046] The composite powder is loaded into a turntable powder feeder, and the powder is delivered to the workpiece surface using high-purity argon gas with a pressure of 0.2MPa and a purity of 99.99%. Simultaneously, an ultra-high-speed laser melting deposition equipment is used to melt the powder, and a laser-deposited high-entropy alloy composite coating is formed after the multiple overlapping molten pools are cooled and solidified.

[0047] Ultra-high-speed laser melting deposition process parameters: substrate preheating temperature ≥ 250°C, spot diameter 5mm, overlap rate 40%, laser power 3500W, scanning line speed 10mm / s, powder feeding rate 15g / min.

[0048] The prepared coating thickness is about 1.0mm, and the microhardness is ≥785HV 0.2 .

[0049] Embodiment 2:

[0050] (1) High entropy alloy composite material formulation

[0051] The invention provides a formula of a dual in-situ precipitation-reinforced FeCoNiCr-based high-entropy alloy composite material with low corrosion-wear synergistic effect, which comprises 12 at% Al, 12 at% Co, 12 at% Cr, 12 at% Fe, 12 at% Ni, 25 at% Ti and 15 at% C, calculated by atomic percentage.

[0052] (2) Preparation method of high entropy alloy composite material powder raw material

[0053] According to the above-mentioned formula, pure metal powder with a purity of not less than 99.9% and a powder particle size of 45 to 105 μm is used as the raw material. Al powder, Co powder, Cr powder, Fe powder, Ni powder, Ti powder and graphene powder are mixed and loaded into a stainless steel ball mill, and stainless steel grinding balls with a diameter of 10 mm are added, and the ball-to-material mass ratio is 1.5:1. Subsequently, high-purity argon protective gas with a purity higher than 99.99% is filled into the tank, and after sealing, it is placed in a drum ball mill for ball milling at 90 r / min and mixed for 3 hours to obtain a composite powder material.

[0054] The microstructure of the FeCoNiCr-based high entropy alloy composite material mixed powder in this embodiment is as follows Figure 1 As shown in the figure, it can be seen that graphene is relatively evenly coated on the surface of the spherical metal powder, providing good conditions for the subsequent diffusion and reaction of carbon elements.

[0055] (3) Preparation method of high entropy alloy composite coating

[0056] The surface of the workpiece made of 2205 duplex steel is degreased, decontaminated and derusted, and then cleaned with alcohol or acetone.

[0057] The composite powder is loaded into a turntable powder feeder, and the powder is delivered to the workpiece surface using high-purity argon gas with a pressure of 0.25 MPa and a purity of 99.99%. Simultaneously, an ultra-high-speed laser melting deposition equipment is used to melt the powder, and a laser-deposited high-entropy alloy composite coating is formed after the multiple overlapping molten pools are cooled and solidified.

[0058] Ultra-high-speed laser melting deposition process parameters: substrate preheating temperature ≥ 150°C, spot diameter 5mm, overlap rate 50%, laser power 2500W, scanning line speed 20mm / s, powder feeding rate 25g / min.

[0059] The coating thickness is about 2.0mm, and the microhardness is ≥720HV 0.2 .

[0060] The microstructure of the FeCoNiCr-based high entropy alloy composite coating in this embodiment is as follows: Figure 2 As shown in the figure, it can be seen that the TiC particle reinforcement phase is evenly distributed in the coating, which has a good dispersion strengthening effect. Figure 3 As shown in the figure, it can be seen that the B2 nano-precipitate phase and TiC ceramic particles are distributed in the coating at the same time, playing a synergistic strengthening role. After SKPFM testing, the surface potential distribution of the composite coating is as follows Figure 4 As shown in the figure, it can be seen that there is a lower potential difference (up to 80mV) between the TiC particle phase and the surrounding matrix, reflecting a lower tendency to galvanic corrosion.

[0061] Embodiment 3:

[0062] (1) High entropy alloy composite material formulation

[0063] The invention provides a formula of a dual in-situ precipitation-reinforced FeCoNiCr-based high-entropy alloy composite material with low corrosion-wear synergistic effect, which comprises 15at% Al, 15at% Co, 15at% Cr, 15at% Fe, 15at% Ni, 20at% Ti and 5at% C calculated by atomic percentage.

[0064] (2) Preparation method of high entropy alloy composite material powder raw material

[0065] According to the above-mentioned formula, pure metal powder with a purity of not less than 99.9% and a powder particle size of 45 to 105 μm is used as the raw material. Al powder, Co powder, Cr powder, Fe powder, Ni powder, Ti powder and graphene powder are mixed and loaded into a stainless steel ball mill, and stainless steel grinding balls with a diameter of 10 mm are added, and the ball-to-material mass ratio is 1:1. Subsequently, high-purity argon protective gas with a purity higher than 99.99% is filled into the tank, and after sealing, it is placed in a drum ball mill for ball milling at 60 r / min and mixed for 2 hours to obtain a composite powder material.

[0066] (3) Preparation method of high entropy alloy composite coating

[0067] The surface of the workpiece made of 0Cr13Ni5Mo steel is degreased, decontaminated and derusted, and then cleaned with alcohol or acetone.

[0068] The composite powder is loaded into a turntable powder feeder, and the powder is delivered to the workpiece surface using high-purity argon gas with a pressure of 0.35MPa and a purity of 99.99%. Simultaneously, an ultra-high-speed laser melting deposition equipment is used to melt the powder, and a laser-deposited high-entropy alloy composite coating is formed after the multiple overlapping molten pools are cooled and solidified.

[0069] Ultra-high-speed laser melting deposition process parameters: spot diameter 3 mm, overlap rate 60%, laser power 2000 W, scanning line speed 50 mm / s, powder feeding rate 35 g / min.

[0070] The coating thickness is about 3.0mm, and the microhardness is ≥680HV 0.2 .

[0071] Comparative Example:

[0072] (1) Ex-situ TiC reinforced high entropy alloy composite formulation

[0073] A conventional equiatomic ratio FeCoNiCrAl high entropy alloy is used as the metal matrix, and a certain proportion of TiC is added to form an ex-situ ceramic reinforced high entropy alloy composite material formula, which includes Al 18at%, Co 18at%, Cr 18at%, Fe 18at%, Ni 18at%, and TiC 10at%, calculated by atomic percentage.

[0074] (2) Preparation method of non-in-situ TiC reinforced high entropy alloy composite powder

[0075] According to the above-mentioned formula, pure metal powder with a particle size of 45 to 105 μm and TiC powder with a particle size of 2 to 10 μm are used as raw materials, Al powder, Co powder, Cr powder, Fe powder, Ni powder and TiC powder are mixed and loaded into a stainless steel ball mill, and stainless steel grinding balls with a diameter of 10 mm are added, and the ball-to-material mass ratio is 1:1. Subsequently, high-purity argon protective gas with a purity higher than 99.99% is filled into the tank, and after sealing, it is placed in a drum ball mill for ball milling at 120 r / min and mixed for 5 hours to obtain a composite powder material.

[0076] (3) Preparation method of non-in-situ TiC reinforced high entropy alloy composite coating

[0077] The surface of the workpiece made of 2205 duplex steel is degreased, decontaminated and derusted, and then cleaned with alcohol or acetone.

[0078] The non-in-situ composite powder is loaded into a turntable powder feeder, and the powder is delivered to the workpiece surface using high-purity argon gas with a pressure of 0.25MPa and a purity of 99.99%. Conventional laser cladding equipment is simultaneously used to melt the powder, and a high-entropy alloy composite coating is formed after the multiple overlapping molten pools are cooled and solidified.

[0079] Laser cladding process parameters: substrate preheating temperature ≥ 150 °C, spot diameter 5 mm, overlap rate 60%, laser power 2500 W, scanning line speed 10 mm / s, powder feeding rate 25 g / min.

[0080] The coating thickness is about 2.5mm, and the microhardness is ≥475HV 0.2 .

[0081] The microstructure of the laser cladding non-in-situ TiC reinforced high entropy alloy composite coating in this comparative example is as follows: Figure 5 As shown in the figure, it can be seen that there are fewer TiC particle reinforcement phases distributed in the coating. This is because the TiC particles melt and decompose on the surface under the action of the high-energy density laser beam, and the strengthening effect is weakened. Figure 6 As shown in the figure, the matrix is ​​a dendrite structure, and no nano-precipitation phase reinforcement particles are found. In addition, the SKPFM test shows that the surface potential distribution of the coating is as follows Figure 7 As shown in the figure, it can be seen that there is a high potential difference (up to 100mV) between the TiC particle phase and the surrounding matrix, reflecting a high tendency to galvanic corrosion.

[0082] As can be seen from the above, the present invention utilizes the solid solution strengthening effect and the multiple in-situ precipitation strengthening effect of micron-sized TiC and nano-sized precipitated B2 to obtain a high-entropy alloy composite material with high hardness, high wear resistance and high corrosion resistance. The prepared coating has a uniform and dense structure, is metallurgically bonded to the substrate, and has excellent anti-corrosion friction performance and low corrosion-wear synergistic effect.

[0083] The above specific implementation modes are used to explain the present invention rather than to limit the present invention. Any modification and change made to the present invention within the spirit of the present invention and the protection scope of the claims shall fall within the protection scope of the present invention.

[0084] The above description is only a preferred embodiment of the present invention, so all equivalent changes or modifications made according to the structure, characteristics and principles described in the scope of the patent application of the present invention are included in the scope of the patent application of the present invention.

Claims

1. A dual in-situ precipitation-reinforced FeCoNiCr-based high entropy alloy composite material formula with low corrosion-wear synergistic effect, characterized in that: Calculated by atomic percentage = content, it includes Al 15-30at%, Co 10-25at%, Cr 10-25at%, Fe10-25at%, Ni 10-25at%, Ti 20-35at%, and C 5-15at%.

2. The dual in-situ precipitation-reinforced FeCoNiCr-based high entropy alloy composite material with low corrosion-wear synergistic effect according to claim 1, characterized in that: The Ti / Al ratio ranges from 1.2 to 2.3: the Ti / C ratio ranges from 1.5 to 5.

5.

3. A method for preparing a dual in-situ precipitation-reinforced FeCoNiCr-based high-entropy alloy composite material with low corrosion-wear synergistic effect, characterized in that: The method specifically comprises: firstly, according to the material formula of any one of claims 1 to 2, metal powders of Al powder, Co powder, Cr powder, Fe powder, Ni powder and Ti powder and graphene powder are loaded into a stainless steel ball milling jar, and stainless steel grinding balls are added; then, argon protective gas is filled into the jar, and the jar is sealed and placed in a ball mill for ball milling, and after the ball milling is completed, the grinding balls are taken out to obtain a mixed powder in which graphene is evenly coated on the surface of metal powder particles.

4. The method for preparing a dual in-situ precipitation-reinforced FeCoNiCr-based high entropy alloy composite material with low corrosion-wear synergistic effect according to claim 3, characterized in that: In the method, metal powder with a purity of not less than 99.9% and a particle size of 30 to 150 μm and graphene powder with a purity of not less than 95% and a particle size of 0.5 to 1 μm are used as raw materials, stainless steel grinding balls with a diameter of 5 mm are added, and the mass ratio of the stainless steel balls to the raw materials is (0.5 to 2):

1.

5. The method for preparing a dual in-situ precipitation-reinforced FeCoNiCr-based high entropy alloy composite material with low corrosion-wear synergistic effect according to claim 3, characterized in that: In the method, the ball milling is performed at a rotation speed of 60 to 120 r / min for 2 to 5 hours.

6. A method for preparing a dual in-situ precipitation-enhanced FeCoNiCr-based high entropy alloy composite coating with low corrosion-wear synergistic effect, characterized in that: The composite material according to any one of claims 1 to 2 or the composite material obtained by the preparation method according to any one of claims 3 to 5 is used as a raw material and is prepared on the surface of a stainless steel or carbon steel workpiece by adopting an ultra-high-speed laser melting deposition process.

7. The method for preparing a dual in-situ precipitation-enhanced FeCoNiCr-based high entropy alloy composite coating with low corrosion-wear synergistic effect according to claim 6, characterized in that: The ultra-high-speed laser melting deposition process uses a powder feeder and a high-purity argon gas flow with a purity of not less than 99.99% to transport powder to the surface of the workpiece, and uses an ultra-high-speed laser melting deposition device to melt the coaxial powder flow in the air, and simultaneously melt to form a molten pool, which is then cooled and solidified, and a metallurgically bonded high-entropy alloy composite coating is formed through multiple overlaps.

8. The method for preparing a dual in-situ precipitation-enhanced FeCoNiCr-based high entropy alloy composite coating with low corrosion-wear synergistic effect according to claim 7, characterized in that: In the ultra-high-speed laser melting deposition process, the powder feeding rate is 10-30 g / min, and the argon pressure of the powder-carrying gas during powder feeding is 0.1-0.4 MPa.

9. The method for preparing a dual in-situ precipitation-enhanced FeCoNiCr-based high entropy alloy composite coating with low corrosion-wear synergistic effect according to claim 7, characterized in that: In the ultra-high-speed laser melting deposition process, the preheating temperature is ≥150°C, the laser power of the laser melting deposition equipment is 1500-4500W, the spot diameter is 2-6mm, the overlap rate is 35-65%, and the scanning line speed is 15-50mm / s.

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