Flame-retardant high-entropy alloy coating based on ultrahigh-speed laser cladding and preparation method of flame-retardant high-entropy alloy coating

Abstract

The invention discloses a flame-retardant high-entropy alloy coating based on ultrahigh-speed laser cladding, which is arranged on the surface of a titanium alloy base material, and the flame-retardant high-entropy alloy coating is composed of Al, Cr, Nb, Ti, V, Hf, Ho, La and Gd according to the molar ratio of 4.66: 23.33: 23.33: 23.33: 23.33: 1.0: 0.3: 0.3: 0.4. Al, Cr, Nb, Ti and V are metal block materials with the purity not smaller than 99.99 wt%, and Hf, Ho, La and Gd are metal powder materials with the purity not smaller than 99.99 wt%; the invention further discloses a preparation method of the flame-retardant high-entropy alloy coating based on ultrahigh-speed laser cladding. The flame-retardant high-entropy alloy coating has the advantages of light weight, high temperature resistance, ablation resistance and favorable mechanical properties, and meets the requirements of the existing aerospace field on titanium alloy materials.

Description

Technical Field

[0001] This invention relates to the field of high-entropy alloy coatings. More specifically, this invention relates to a flame-retardant high-entropy alloy coating based on ultra-high-speed laser cladding and its preparation method. Background Technology

[0002] Titanium alloys, due to their high specific strength, good corrosion resistance, excellent high and low temperature performance, and non-toxicity and non-magnetic properties, have become important structural materials for aero engines and gas turbines. However, titanium alloys have low thermal conductivity and possess the highest heat of oxidation and enthalpy of combustion (excluding Al and Mg), as well as a relatively high coefficient of dry friction. During the exchange reaction of oxides at high temperatures, the oxide film can rupture due to volume reduction, losing its sealing performance. This leads to a sharp increase in oxygen transport rate and a rapid rise in temperature, ultimately resulting in combustion. Therefore, titanium alloys suffer from a fatal problem of persistent combustion sensitivity.

[0003] To meet the high-temperature stable service requirements of titanium alloy components for aero-engines and gas turbines, ultra-high-speed laser cladding technology is typically used to form a high-entropy alloy coating on the surface of titanium alloy materials. This high-entropy alloy coating improves the wear resistance, corrosion resistance, heat resistance, and oxidation resistance of the titanium alloy materials. However, titanium alloy components for aero-engines and gas turbines need to operate stably for extended periods under extreme conditions. In addition to high-temperature resistance and ablation resistance, the high-entropy alloy coating on their surface must also possess lightweight properties and good mechanical properties.

[0004] CrMnFeCoNi was the first proposed high-entropy alloy with a single-phase structure. Although it possesses excellent plasticity and toughness, its yield strength and flow stress are insufficient to meet the high load-bearing requirements of aerospace components. This was addressed by introducing Al to form Al... x (CrMnFeCoNi) 1-x The alloy exhibits an evolution in its microstructure from FCC to FCC+BCC to BCC or BCC+B2, which, while increasing strength, reduces toughness. NbMoTaW and NbMoTaWV, representing refractory high-entropy alloys, have room-temperature strains of only about 1.5% and 0.5%, respectively. Although they possess ultra-high temperature strength, their densities are as high as 13.75 g·cm³. -3 and 12.36 g·cm -3 This conflicts with the demand for lightweight aerospace materials. At the same time, such alloys have extremely low room temperature plasticity and are difficult to process and form. The Ta-Nb-Hf-Zr-Ti series of refractory high-entropy alloys, which were developed by replacing Mo and W with Hf, Zr and Ti, can improve toughness, but the density remains high.

[0005] Therefore, there is an urgent need to provide a high-entropy alloy coating that simultaneously possesses lightweight properties, high temperature resistance, ablation resistance, and good mechanical properties to meet the requirements of the current aerospace field for titanium alloy materials. Summary of the Invention

[0006] Another objective of this invention is to provide a flame-retardant high-entropy alloy coating that simultaneously possesses lightweight properties, high temperature resistance, ablation resistance, and good mechanical properties, in order to meet the requirements of the current aerospace field for titanium alloy materials.

[0007] To achieve these objectives and other advantages according to the present invention, a flame-retardant high-entropy alloy coating based on ultra-high-speed laser cladding is provided, which is disposed on the surface of a titanium alloy substrate. The flame-retardant high-entropy alloy coating is composed of Al, Cr, Nb, Ti, V, Hf, Ho, La, and Gd in a molar ratio of 4.66:23.33:23.33:23.33:23.33:1.0:0.3:0.3:0.4. Among them, Al, Cr, Nb, Ti and V are bulk metal materials with a purity of not less than 99.99 wt%, and Hf, Ho, La and Gd are powder metal materials with a purity of not less than 99.99 wt%.

[0008] A method for preparing a flame-retardant high-entropy alloy coating based on ultra-high-speed laser cladding includes the following steps: S1. Mix the raw materials Al, Cr, Nb, Ti, V, Hf, Ho, La, and Gd in the specified proportions and place them in a water-cooled copper crucible. Evacuate the mixture until the vacuum level is less than 2 × 10⁻⁶. -3 Pa; S2. Using a non-consumable vacuum arc melting method, the raw materials in S1 are melted in a high-purity argon atmosphere to prepare a high-entropy alloy ingot. S3. High-entropy alloy powder is prepared from high-entropy alloy ingots by gas atomization. S4. Pre-treat the surface of the titanium alloy substrate; S5. Using ultra-high-speed laser cladding technology, high-entropy alloy powder is clad onto the surface of a titanium alloy substrate within a gas-protected chamber to prepare Al. 0.2 CrNbTiV- Hf 1.0 Ho 0.3 La 0.3 Gd 0.4 Flame-retardant high-entropy alloy coating.

[0009] Preferably, in S4, the process of pre-treating the surface of the titanium alloy substrate is as follows: first, the surface of the titanium alloy substrate is finely ground until its surface roughness is lower than Ra6mm, and then acetone is used to clean the oil stains on the surface of the titanium alloy material.

[0010] Preferably, in S3, the high-entropy alloy powder prepared has a spherical morphology, a smooth surface, and a particle size of 50~150μm.

[0011] Preferably, in S1, the number of smelting times is no less than 5.

[0012] Preferably, in S5, the laser output power of the laser cladding is 1.5-4.0kW, the wavelength is 915-1060nm, the laser spot diameter is 2-3 mm, and the laser energy is distributed in a Gaussian manner; the cladding speed is greater than 150mm / s, the powder beam diameter is 1-1.5 mm, the powder utilization rate is >80%, and the overlap rate is 70-80%; argon is used as the protective gas during the cladding process, the carrier gas flow rate is 6-8L·min-1, and the protective gas flow rate is 1-1.5L·min-1.

[0013] Preferably, in S5, the coating dilution rate of laser cladding is calculated using the following formula: ; In the formula, ρ p ρ is the powder density; s Density of the matrix material; X c The mass percentage of element X in the entire coating; X p This represents the mass percentage of element X in the powder. X s This represents the mass percentage of element X in the matrix.

[0014] This invention offers at least the following advantages: To avoid the high density of refractory high-entropy alloy systems, which is detrimental to the lightweight design of titanium alloy structural components, this invention designs a lightweight Al-Cr-Nb-Ti-V refractory high-entropy alloy composition system based on the microstructure, mechanical properties, and JMat Pro simulated phase diagram analysis of Al-Cr-Nb-Ti-V refractory high-entropy alloys. Furthermore, by adding Hf, Ho, La, and Gd, and through reasonable control of the composition structure, the high-temperature resistance of the Al-Cr-Nb-Ti-V high-entropy alloy is improved. The close-packed hexagonal structure formed by rare earth elements increases the atomic size difference in the alloy, enhancing the interaction between elements and promoting the formation of the B2 phase, σ phase, and Laves phase. By forming an equal and ordered structure, a cladding material with good comprehensive mechanical properties is designed. Then, for titanium alloy, a material with low thermal conductivity, in order to ensure high consistency between the coating and the high-entropy alloy design material, the cladding material is clad onto the surface of the titanium alloy material based on the control method of ultra-high speed laser cladding dilution rate and the coating dilution rate control criterion. Finally, a flame-retardant high-entropy alloy coating with good mechanical properties is obtained, which is lightweight, high temperature resistant, ablation resistant and meets the requirements of the current aerospace field for titanium alloy materials.

[0015] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0016] Figure 1 This is an image of the high-entropy alloy powder from Embodiment 1 of the present invention; Figure 2 This is an image of the surface of the flame-retardant high-entropy alloy coating of Embodiment 1 of the present invention; Figure 3 This is a cross-sectional elemental distribution diagram of the flame-retardant high-entropy alloy coating of Embodiment 1 of the present invention; Figure 4 This is a SEM image of the surface morphology of the flame-retardant high-entropy alloy coating in Example 1 of the present invention; Figure 5 This is a surface morphology image of the flame-retardant high-entropy alloy coating after ablation in Example 1 of the present invention; Figure 6 Image of the coating surface in Comparative Example 1; Figure 7 Image of the CuAlNiCrFe coating surface in Comparative Example 2; Figure 8 The image shows the surface morphology of the CuAlNiCrFe coating after ablation, as shown in Comparative Example 2. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0018] It should be noted that, unless otherwise specified, the experimental methods described in the following embodiments are all conventional methods, and the reagents and materials described are all commercially available unless otherwise specified. In the description of this invention, the terms "lateral", "longitudinal", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0019] like Figure 1-8 As shown, this invention provides a flame-retardant high-entropy alloy coating based on ultra-high-speed laser cladding, which is applied to the surface of a titanium alloy substrate. The flame-retardant high-entropy alloy coating is composed of Al, Cr, Nb, Ti, V, Hf, Ho, La, and Gd in a molar ratio of 4.66:23.33:23.33:23.33:23.33:1.0:0.3:0.3:0.4. Among them, Al, Cr, Nb, Ti and V are bulk metal materials with a purity of not less than 99.99 wt%, and Hf, Ho, La and Gd are powder metal materials with a purity of not less than 99.99 wt%.

[0020] In the above technical solutions, to avoid the high density of refractory high-entropy alloy systems, which is detrimental to the lightweight design concept of titanium alloy structural components, this invention designs a lightweight Al-Cr-Nb-Ti-V refractory high-entropy alloy composition system based on the microstructure, mechanical properties, and JMatPro simulated phase diagram analysis of Al-Cr-Nb-Ti-V refractory high-entropy alloys. Furthermore, by adding Hf, Ho, La, and Gd, and through reasonable control of the composition structure, the high-temperature resistance of the Al-Cr-Nb-Ti-V high-entropy alloy is improved. The close-packed hexagonal structure formed by rare earth elements increases the atomic size difference in the alloy, enhancing the interaction between elements and promoting the formation of the B2 phase, σ phase, and Laves phase. By forming an equal and ordered structure, a cladding material with good comprehensive mechanical properties is designed. Then, for titanium alloy, a material with low thermal conductivity, in order to ensure high consistency between the coating and the high-entropy alloy design material, the cladding material is clad onto the surface of the titanium alloy material based on the control method of ultra-high speed laser cladding dilution rate and the coating dilution rate control criterion, and finally a flame-retardant high-entropy alloy coating with good mechanical properties is obtained.

[0021] A method for preparing a flame-retardant high-entropy alloy coating based on ultra-high-speed laser cladding includes the following steps: S1. Mix the raw materials Al, Cr, Nb, Ti, V, Hf, Ho, La, and Gd in a ratio of 4.66:23.33:23.33:23.33:23.33:1.0:0.3:0.3:0.4 and place them in a water-cooled copper crucible. Evacuate the mixture until the vacuum level is less than 2 × 10⁻⁶. -3 Pa; S2. Using a non-consumable vacuum arc melting method, the raw materials in S1 are melted in a high-purity argon atmosphere to avoid alloy oxidation. The sample is repeatedly melted at least 5 times to eliminate alloy component segregation and ensure uniform element distribution, ultimately preparing Al with a smooth surface and no oxide layer. 0.2 CrNbTiV- Hf 1.0 Ho 0.3 La 0.3 Gd 0.4 High-entropy alloy button ingots; S3. High-entropy alloy button ingots are prepared into Al atoms with spherical morphology, smooth surface, and particle size of 50~150μm by gas atomization. 0.2 CrNbTiV- Hf 1.0 Ho 0.3 La 0.3Gd 0.4 High-entropy alloy powder; S4. Before cladding, the surface of the titanium alloy substrate is finely ground until its surface roughness is lower than Ra6mm, and then the surface of the titanium alloy material is cleaned with acetone to remove oil stains. S5. Ultra-high-speed laser cladding technology utilizes an ultra-high-speed laser cladding system. Based on the optimized design of the coaxial powder feeding nozzle, it achieves the best coupling between powder particles and the laser beam. The high-energy-density laser beam simultaneously melts the powder and a thin layer on the surface of the high-speed moving substrate material. After rapid solidification, a cladding layer with extremely low dilution and metallurgical bonding with the substrate is formed, which significantly improves the wear resistance, corrosion resistance, heat resistance, oxidation resistance and other process characteristics of the substrate material surface. The ultra-high-speed laser cladding system includes a fiber laser, a powder feeding nozzle, a robotic arm, a powder feeder and a gas protection box. To ensure high consistency between the coating and the high-entropy alloy design material, ultra-high-speed laser cladding technology was employed. High-entropy alloy powder was clad onto the surface of a titanium alloy substrate within a gas-protected chamber. Argon gas (99.99%, 0.5 L·min⁻¹) was continuously introduced into the chamber to prevent coating oxidation or titanium alloy nitriding, thus preparing Al… 0.2 CrNbTiV- Hf 1.0 Ho 0.3 La 0.3 Gd 0.4 Flame-retardant high-entropy alloy coating, specifically: In the ultra-high-speed laser cladding process, a robotic arm is used to hold the powder feeding nozzle and perform low-speed linear motion, maintaining the nozzle at the same height from the substrate surface to avoid affecting the laser energy distribution and powder delivery stability due to the moving speed. A small lathe is used to hold the titanium alloy substrate and perform high-speed rotational motion. The efficient preparation of the cladding coating on the substrate surface is achieved through the combination of these two movements. The laser output power is 1.5-4.0kW, the laser wavelength is 915-1060nm, the laser spot is circular with a diameter of 2-3 mm, and the laser energy is distributed in a Gaussian manner. The cladding speed is greater than 150mm / s, the powder beam diameter of the powder feeding nozzle is 1-1.5 mm, the powder utilization rate is >80%, and the overlap rate of the high-entropy alloy flame-retardant coating is 70-80%. The carrier gas flow rate is 6-8L·min⁻¹, and the protective gas flow rate is 1-1.5L·min⁻¹. The dilution rate of the laser cladding coating is calculated using the following formula: ; In the formula, ρ p ρ is the powder density; s Density of the matrix material; X c The mass percentage of element X in the entire coating; X p This represents the mass percentage of element X in the powder.X s This represents the mass percentage of element X in the matrix.

[0022] <Example 1> Preparation of a flame-retardant high-entropy alloy coating based on ultra-high-speed laser cladding: S1. Al, Cr, Nb, Ti, V, Hf, Ho, La, and Gd, all with a purity of 99.99 wt%, are mixed in a molar ratio of 4.66:23.33:23.33:23.33:23.33:1.0:0.3:0.3:0.4 and placed in a water-cooled copper crucible. The mixture is then evacuated to a vacuum level of 1.5 × 10⁻⁶. -3 Pa; S2. Using a non-consumable vacuum arc melting method, the raw materials are repeatedly melted five times under a high-purity argon atmosphere to obtain Al. 0.2 CrNbTiV- Hf 1.0 Ho 0.3 La 0.3 Gd 0.4 High-entropy alloy button ingots; S3. High-entropy alloy ingots are prepared into Al atoms with spherical morphology, smooth surface, and a particle size of 60 μm by gas atomization. 0.2 CrNbTiV- Hf 1.0 Ho 0.3 La 0.3 Gd 0.4 High-entropy alloy powder, powder image as follows Figure 1 As shown; S4. The base material is a Ti-6Al-4V titanium alloy (TC4) bar with a size of φ30 mm. First, the surface of the TC4 bar is finely ground to a surface roughness of Ra5 mm, and then the oil stains on the surface of the bar are cleaned with acetone. S5. Using ultra-high-speed laser cladding technology, argon gas is continuously introduced into a gas-protected chamber, and high-entropy alloy powder is clad onto the surface of TC4 rods to obtain Al. 0.2 CrNbTiV- Hf 1.0 Ho 0.3 La 0.3 Gd 0.4 Flame-retardant high-entropy alloy coating; the laser output power is 2.0kW, the wavelength is 1000nm, the laser spot diameter is 2mm, and the laser energy is distributed in a Gaussian manner; the cladding speed is 200mm / s, the powder beam diameter is 1.7mm, the powder utilization rate is 90%, and the overlap rate is 70%; the carrier gas flow rate is 6L·min-1, and the protective gas flow rate is 1L·min-1; the coating dilution rate is calculated to be 3.1% using a formula.

[0023] <Comparative Example 1> A method for preparing a flame-retardant high-entropy alloy coating differs from Example 1 in that, in step S5, the flame-retardant high-entropy alloy coating is prepared using HVOF supersonic flame spraying technology, while the remaining conditions and parameters are the same as in Example 1.

[0024] <Comparative Example 2> A method for preparing a CuAlNiCrFe coating, wherein the cladding material is CuAlNiCrFe powder, and the remaining conditions and parameters are the same as in Example 1.

[0025] The macroscopic surface, cross-sectional morphology, and chemical composition of the coatings in Example 1 and Comparative Examples 1-2 were analyzed. The analysis process is as follows: Example 1: Coated surface as shown Figure 2 As shown, the coating thickness is 180 μm. No obvious cracks or bonding defects were observed at the coating / substrate interface. There is a clear fusion line between the coating and the substrate, indicating that a good metallurgical bond has been formed between the coating and the substrate.

[0026] The elemental distribution of the coating cross section was characterized using Nb, such as Figure 3 As shown, SEM-EDS line scan results indicate that, due to the dilution effect of the substrate, the Nb content in the bonding region gradually decreases from the coating to the substrate, further demonstrating a high-strength metallurgical bond between the coating and the substrate. Furthermore, the coating's transition zone size is only 2 μm under low heat input, smaller than previously reported data for laser-clad high-entropy alloy coatings, indicating that ultra-high-speed laser cladding technology is more effective in controlling the thermal influence on the substrate.

[0027] The surface morphology of the coating after isothermal oxidation at 650°C in air for 50 h is shown in the SEM image. Figure 4 As shown, the oxide layers formed by coatings with different dilution rates are all relatively continuous and dense. The coatings are not exposed to the air atmosphere. The oxide layers formed by the coatings are mainly composed of fine granular or flaky light gray oxide structures, with a few coarser dark gray near-cubic oxide structures distributed on or embedded in the oxide layers. The oxide layers are relatively dense overall, exhibiting complete metallurgical bonding.

[0028] For Al 0.2 CrNbTiV- Hf 1.0 Ho 0.3 La 0.3 Gd 0.4 Laser ablation simulation of titanium alloy combustion was conducted on a flame-retardant high-entropy alloy coating. The surface morphology of the coating after ablation is as follows: Figure 5 As shown, under the protection of the coating, the area of ​​the ablation zone on the surface is small, and the depth of the pits caused by material damage is shallow, indicating that Al 0.2 CrNbTiV- Hf 1.0 Ho 0.3La 0.3 Gd 0.4 The coating can help to hinder laser ablation to some extent.

[0029] Comparative Example 1: Coated surface as shown Figure 6 As shown, interfacial hindrance and uneven element diffusion exist at the coating / substrate interface.

[0030] The morphology of the CuAlNiCrFe coating in Comparative Example 2 is as follows: Figure 7 As shown, the coating has a uniform, dense, and continuous overall structure, free from defects such as pores and cracks. The oxide layer is relatively dense overall, exhibiting complete metallurgical bonding.

[0031] Laser ablation simulation of titanium alloy combustion was performed on the CuAlNiCrFe coating. The surface morphology of the CuAlNiCrFe coating after ablation is as follows: Figure 8 As shown, the ablation area on the CuAlNiCrFe coating surface has a diameter of approximately 3200 μm, including surrounding combustion products and a central ablation pit. The ablation pit is blind-hole shaped, with a diameter of approximately 2000 μm and a depth of approximately 1400 μm. The ablation products are concentrated at the top of the ablation pit, with a relatively loose structure and the presence of pores and cracks, which can serve as diffusion channels for oxygen. The ablation products consist of high-valence oxides of Ti and a small amount of Al oxides. There is a cracked and broken titanium oxide film on the surface. Therefore, the oxide film of the CuAlNiCrFe coating cannot resist O intrusion and cannot hinder the ablation process.

[0032] As can be seen from Example 1 and Comparative Example 1, although the same material system was used, the different intrinsic diffusion mechanisms inside the thermal spray coating resulted in interface hindrance and uneven element diffusion at the coating / substrate interface in Comparative Example 1. The flame-retardant high-entropy alloy powder of the present invention has better compatibility with ultra-high-speed laser cladding technology. As can be seen from Example 1 and Comparative Example 2, the Al of the present invention... 0.2 CrNbTiV- Hf 1.0 Ho 0.3 La 0.3 Gd 0.4 Compared with CuAlNiCrFe high-entropy alloy coatings, the area of ​​severe material damage is reduced by more than 80%. The flame-retardant high-entropy alloy coating of this invention can make the titanium alloy surface protection have both certain high-temperature stability and good ablation resistance, and can hinder laser ablation.

[0033] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A fire-retardant high-entropy alloy coating based on ultra-high-speed laser cladding, which is arranged on the surface of a titanium alloy substrate, characterized in that, The fire-retardant high-entropy alloy coating is composed of Al, Cr, Nb, Ti, V, Hf, Ho, La, Gd in a molar ratio of 4.66:23.33:23.33:23.33:23.33:1.0:0.3:0.3:0.4; wherein, Al, Cr, Nb, Ti and V are metal bulk materials with a purity of not less than 99.99wt%, and Hf, Ho, La and Gd are metal powder materials with a purity of not less than 99.99wt%.

2. A method for preparing a flame-retardant high-entropy alloy coating based on ultrafast laser cladding according to claim 1, characterized in that, The method comprises the following steps: S1, raw materials Al, Cr, Nb, Ti, V, Hf, Ho, La, Gd are mixed in proportion and placed in a water-cooled copper crucible, vacuumed to a vacuum degree less than 2x10 -3 Pa; S2, using a non-consumable vacuum arc melting method, the raw materials in S1 are refined under a high-purity argon atmosphere to prepare a high-entropy alloy ingot; S3, using a gas atomization method, the high-entropy alloy ingot is prepared to form a high-entropy alloy powder; S4, the surface of the titanium alloy substrate is pretreated; S5, using ultra-high-speed laser cladding technology, high-entropy alloy powder is cladded on the surface of titanium alloy substrate in a gas protection box to obtain Al 0.2 CrNbTiV-Hf 1.0 Ho 0.3 La 0.3 Gd 0.4 Flame-retardant high-entropy alloy coating.

3. The method for preparing flame-retardant high-entropy alloy coating based on ultrafast laser cladding according to claim 2, wherein, In S4, the process of pretreating the surface of the titanium alloy substrate is: first, the surface of the titanium alloy substrate is finely ground to a surface roughness of less than Ra6mm, and then the surface of the titanium alloy material is cleaned with acetone to remove oil stains.

4. The method for preparing flame-retardant high-entropy alloy coating based on ultrafast laser cladding according to claim 2, wherein, In S3, the high-entropy alloy powder prepared has a spherical shape and a smooth surface, and the particle size is 50-150μm.

5. The method for preparing flame-retardant high-entropy alloy coating based on ultrafast laser cladding according to claim 2, wherein, In S1, the melting frequency is not less than 5 times.

6. The method for preparing flame-retardant high-entropy alloy coating based on ultrafast laser cladding according to claim 2, wherein, In S5, the laser output power of the laser cladding is 1.5-4.0kW, the wavelength is 915-1060nm, the laser spot diameter is 2-3mm, and the laser energy is distributed in a Gaussian form; the cladding speed is greater than 150mm / s, the powder beam diameter is 1-1.5mm, the powder utilization rate is >80%, and the overlap rate is 70-80%; argon is used as the protective gas during the cladding process, the carrier gas flow is 6-8L·min-1, and the protective gas flow is 1-1.5L·min-1.

7. The method for preparing flame-retardant high-entropy alloy coating based on ultrafast laser cladding according to claim 2, wherein, In S5, the coating dilution rate of the laser cladding is calculated by the following formula: ； wherein p p is the powder density; p s is the bulk material density; X c is the mass percentage of the element X in the entire coating; X p is the mass percentage of the element X in the powder; X s is the mass percentage of the element X in the bulk.

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