High-entropy alloy flux-cored wire for preparing wear-resistant coating on TC4 titanium alloy surface as well as preparation method and application of high-entropy alloy flux-cored wire

Abstract

The invention discloses a high-entropy alloy flux-cored wire for preparing a wear-resistant coating on a TC4 titanium alloy surface, the high-entropy alloy flux-cored wire comprises a flux core and a welding skin, the flux core comprises the following components in atomic percent: 20% of Ta, 30% of W, 22-28% of V and 22-28% of Mo, and the sum of the atomic percent of the components is 100%. According to the high-entropy alloy flux-cored wire and the preparation method thereof, the problem that in the prior art, the hardness of a coating is reduced due to the hydrogen embrittlement phenomenon easily caused in the welding process of the flux-cored wire is solved, and the wear-resistant coating prepared on the TC4 titanium alloy surface through the high-entropy alloy flux-cored wire is good in wear resistance. The invention further discloses a preparation method and application of the high-entropy alloy flux-cored wire.

Description

Technical Field

[0001] The present invention belongs to the technical field of flux-cored wires, and relates to a high-entropy alloy flux-cored wire for preparing a wear-resistant coating on the surface of TC4 titanium alloy. The present invention also relates to a preparation method of the above-mentioned high-entropy alloy flux-cored wire, and the present invention also relates to the application of the above-mentioned high-entropy alloy flux-cored wire. Background Art

[0002] In the field of shipbuilding industry, the working environment of ship propeller blades is extremely harsh. Since the propeller blades work underwater for a long time, they often encounter different water flow states. Due to the impact of water flow and impurities, the blades are severely worn by friction and have high working stress. Moreover, because seawater contains various halogen ions, it will not only hinder and destroy the passivation reaction of metal elements, but also cause great corrosion to the surface of equipment in contact with seawater. TC4 titanium alloy has a low density, high strength, good high- and low-temperature resistance and corrosion resistance. Compared with other welding materials, it has better joint strength, which just meets the complex working conditions of ship propeller blades, so it is often used in the manufacture of ship blades.

[0003] However, due to the poor surface properties of TC4 titanium alloy, such as relatively low hardness, poor surface wear resistance and corrosion resistance, etc., these defects limit its use in high-demand application scenarios such as ship propeller blades to a certain extent. In order to overcome these limitations, improve the comprehensive performance of TC4 titanium alloy, and meet wider application requirements, preparing a modified coating on the surface of titanium-aluminum is an effective method to improve its surface performance.

[0004] The high-entropy alloy system has a high mixing entropy and a low Gibbs free energy. During the solidification process, it tends to form a simple face-centered cubic (FCC) or body-centered cubic (BCC) solid solution structure, rather than a variety of complex intermetallic compounds. It has a high-entropy effect thermodynamically, a lattice distortion effect structurally, a retarded diffusion effect kinetically, and a cocktail effect in terms of performance. Therefore, high-entropy alloys have a series of advantages such as high strength, high hardness, high temperature resistance, good corrosion resistance, good radiation resistance and high wear resistance, and are widely used in many manufacturing fields.

[0005] At present, the preparation methods for preparing a high-entropy alloy cladding layer on the surface of TC4 titanium alloy are laser cladding and surface thermal spraying; the single-pass melt width of laser cladding is relatively narrow (usually <5 mm), and multi-pass overlapping is required to achieve large-area coverage. It is easy to produce non-uniform microstructure in the overlapping area, and the forming cycle is long. The required supporting facilities and working environment are strict and the cost is high. The process flexibility is poor, and the flux-cored wires used for laser cladding generally have poor uniformity of the flux composition, alloy element burning and oxidation, are easy to absorb moisture, and are prone to hydrogen embrittlement during the welding process, resulting in a decrease in the hardness of the coating.

[0006] Surface thermal spraying has a natural disadvantage in terms of bonding strength and matrix bonding compatibility compared to chemically bonded TIG welding due to mechanical bonding, and cannot be applied in high-strength bonding fields in the shipbuilding industry. Summary of the Invention

[0007] The object of the present invention is to provide a high-entropy alloy flux-cored wire for preparing a wear-resistant coating on the surface of TC4 titanium alloy, which solves the problem in the prior art that the flux-cored wire is prone to hydrogen embrittlement during welding, resulting in a decrease in the hardness of the coating. Using this high-entropy alloy flux-cored wire to prepare a wear-resistant coating on the surface of TC4 titanium alloy has good wear resistance.

[0008] Another object of the present invention is to provide a preparation method of the above high-entropy alloy flux-cored wire.

[0009] The third object of the present invention is to provide the application of the above high-entropy alloy flux-cored wire.

[0010] The technical solution adopted by the present invention is a high-entropy alloy flux-cored wire for preparing a wear-resistant coating on the surface of TC4 titanium alloy, including a flux core and a welding skin. The flux core is composed of the following components according to atomic percentage: Ta: 20%, W: 30%, V: 22-28%, Mo: 25-28%, and the sum of the atomic percentages of the above components is 100%.

[0011] Preferably, the welding skin is a TA1 titanium alloy strip, and the welding skin is composed of the following components according to mass percentage: Fe: 0.15%, O: 0.12%, C: 0.08%, N: 0.03%, H: 0.015%, and Ti is the balance.

[0012] Preferably, the powder filling rate of the flux core in the flux-cored wire is 30wt% - 40wt%.

[0013] The second technical solution adopted by the present invention is: a preparation method of a high-entropy alloy flux-cored wire, for preparing the above high-entropy alloy flux-cored wire for preparing a wear-resistant coating on the surface of TC4 titanium alloy, which is specifically implemented according to the following steps: Step 1, ultrasonically clean and dry the TA1 strip of the welding skin; Step 2, weigh the following components according to atomic percentage: Ta: 20%, W: 30%, V: 22-28%, Mo: 22-28%, and the sum of the atomic percentages of the above components is 100%; Step 3, mix and heat-dry the metal powders of the components weighed in Step 2 to obtain flux core powder; Step 4, wrap the flux core powder in the TA1 strip processed in Step 1 to make a semi-finished high-entropy alloy flux-cored wire; Step 5, pass the semi-finished high-entropy alloy flux-cored wire obtained in Step 4 through a multi-pass cold drawing and reducing die to obtain the final high-entropy alloy flux-cored wire.

[0014] Preferably, step 1 is specifically as follows: First, clean the TA1 strip of welding skin with a mixed solution of NaOH and acetone, then use deionized water and anhydrous ethanol solution to wash away the remaining mixed solution, and then use a mixed aqueous solution of HF and HNO 3 to perform ultrasonic cleaning. After cleaning, dry it to obtain a cleaned TA1 strip.

[0015] Preferably, in the mixed solution of NaOH and acetone, the mass fraction of NaOH is 25% and the mass fraction of acetone is 75%. In the mixed aqueous solution of HF and HNO 3 the mass fraction of HF is 10%, and the mass fraction of HNO 3 is 30%, and the rest is water. The ultrasonic cleaning time is 8 - 10 min, and the ultrasonic frequency is 30 - 35 kHz.

[0016] Preferably, step 3 is specifically as follows: Mix and heat-dry the metal powders of each component weighed in step 2, and then put the dried powder into a mixer for dry mixing. After the powder is fully mixed, the flux-cored powder is obtained.

[0017] Preferably, in step 4, a flux-cored wire making machine is used to wrap the flux-cored powder uniformly mixed in step 3 in the TA1 strip at a powder filling rate of 30 wt% - 40 wt%, and a forming machine is used to close the TA1 strip to obtain a semi-finished high-entropy alloy flux-cored wire with a diameter of 2.1 mm.

[0018] Preferably, step 5 is specifically as follows: Pass the semi-finished high-entropy alloy flux-cored wire with a diameter of 2.1 mm through wire drawing dies with diameters of 2.0 mm, 1.9 mm, 1.8 mm, 1.7 mm, 1.6 mm, 1.5 mm, 1.42 mm, and 1.2 mm in sequence, and finally obtain a high-entropy alloy flux-cored wire with a diameter of 1.2 mm.

[0019] The third technical solution adopted by the present invention is the application of the high-entropy alloy flux-cored wire. The high-entropy alloy flux-cored wire prepared above is used to prepare a wear-resistant coating on the surface of TC4 titanium alloy. Specifically: Use the high-entropy alloy flux-cored wire to perform cladding on the surface of TC4 titanium alloy. The cladding process is: Use tungsten inert gas welding, the welding current is 150 - 170 A, the voltage is 15 - 25 V, the welding speed is 15 cm / min, and the shielding gas is pure argon.

[0020] The beneficial effects of the present invention are: (1) When the high-entropy alloy flux-cored wire designed by the present invention is used to prepare a corrosion and wear-resistant layer on the surface of titanium alloy, the wear resistance is significantly improved compared with the titanium-aluminum matrix, and it can effectively improve the corrosion and wear problems of ship propeller blades in the high-demand working environment in seawater.

[0021] (2) The wear-resistant coating prepared from the high-entropy alloy flux-cored wire of the present invention has good wear resistance and excellent welding performance. The obtained cladding layer has no welding defects such as pores, inclusions, and cracks, and the prepared coating has good bonding performance with the titanium-aluminum matrix.

[0022] (3) The preparation method of the high-entropy alloy flux-cored wire of the present invention is simple, has low requirements for equipment, good operability, high economic cost performance, and can be mass-produced.

[0023] (4) Based on the high-entropy alloy flux-cored wire, the present invention uses tungsten inert gas welding (TIG) to prepare the wear-resistant layer. Compared with the laser cladding method, TIG welding has the advantages of low cost, high process flexibility, and can be mass-produced; compared with surface thermal spraying, the high-entropy alloy cladding layer obtained by TIG welding has good bonding performance with the TC4 titanium alloy matrix and higher bonding strength. In the field of shipbuilding industry that requires high bonding strength, TIG welding has better application potential than the above two methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is the top crystal phase diagram of the cladding layer obtained by cladding the high-entropy alloy flux-cored wire prepared in Example 7 of the present invention on the surface of TC4 titanium alloy; Figure 2 It is the bottom crystal phase diagram of the cladding layer obtained by cladding the high-entropy alloy flux-cored wire prepared in Example 7 of the present invention on the surface of TC4 titanium alloy. DETAILED DESCRIPTION OF THE INVENTION

[0025] The following is a detailed description in combination with the specific embodiments.

[0026] Example 1 The high-entropy alloy flux-cored wire of the present invention for preparing a wear-resistant coating on the surface of TC4 titanium alloy includes a flux core and a welding skin. The flux core is composed of the following components in atomic percentage: Ta: 20%, W: 30%, V: 22-28%, Mo: 22-28%, and the sum of the atomic percentages of the above components is 100%; The welding skin is a TA1 strip, and the welding skin is composed of the following components in mass percentage: Fe: 0.15%, O: 0.12%, C: 0.08%, N: 0.03%, H: 0.015%, and Ti is the balance; The powder filling rate of the flux core in the flux-cored wire is 30wt% - 40wt%.

[0027] The flux-cored wire selected in the present invention is TaWVMo high-entropy metal flux-cored powder, and the flux-cored powder of the present invention has a duplex structure in a high-entropy miscible state of a bcc phase mainly composed of Ta and V elements and an fcc phase mainly composed of W element. The former has high strength, and the latter has high plasticity. The two appear alternately in a lamellar shape, realizing the alternation of hard and soft phases. The harder precipitation phase improves the overall strength of the alloy, while the cooperative deformation of the precipitation phase and the matrix phase improves the overall plasticity of the alloy. Therefore, it combines the advantages of eutectic and high entropy, showing extremely excellent combination of strength and plasticity.

[0028] The TaWVMo of the present invention has a micron size, which can be effectively and uniformly mixed. Moreover, there is no powder in this flux-cored powder that is easy to react with hydrogen and oxygen elements. Even if a reaction occurs, it can only proceed under high temperature and high pressure. Therefore, the generation of hydrogen embrittlement and oxidation phenomena can be effectively avoided. Therefore, the flux-cored wire of the present invention can effectively solve the problems of poor uniformity of existing flux-cored wires, burning loss and oxidation of alloy elements, and easy reduction of coating hardness caused by hydrogen embrittlement during the welding process.

[0029] The functions of each component in the flux-cored powder are as follows: Ta, W: These two elements belong to the same period in the periodic table of elements, so they have similar electronic structures, chemical properties and element compatibility. Due to having similar lattice structures, they often form substitutional solid solutions, so they are usually designed as the main element elements in high-entropy alloys. In addition, Ta and W also have good corrosion resistance, which significantly improves the corrosion resistance of the high-entropy alloy cladding layer.

[0030] The V element can improve the oxidation resistance of the weld metal, avoid the formation of oxides in the weld metal, so as to maintain good mechanical properties. In addition, the V element can also significantly improve the hardness and strength of the weld metal, and improve its wear resistance and corrosion resistance.

[0031] Mo: The addition of Mo element can improve the fatigue strength and creep resistance of the cladding layer. Secondly, the Mo element can make the high-entropy alloy cladding layer have better corrosion resistance in a corrosive environment, and enable the cladding layer to adapt to complex underwater working environments.

[0032] The welding skin of the present invention is TA1 tape with sufficient Ti. The Ti element can effectively improve the compatibility between the high-entropy alloy and the titanium matrix and improve the interfacial bonding strength. In addition, it can also improve the corrosion resistance of the high-entropy alloy cladding layer.

[0033] Example 2 The preparation method of the high-entropy alloy flux-cored wire of the present invention, which is used to prepare the high-entropy alloy flux-cored wire for preparing a wear-resistant coating on the surface of TC4 titanium alloy in Example 1, is specifically implemented according to the following steps: Step 1, ultrasonically clean and dry the welding skin TA1 tape; Step 2: Weigh the following components according to atomic percentages: Ta: 20%, W: 30%, V: 22 - 28%, Mo: 22 - 28%. The sum of the atomic percentages of the above components is 100%. Step 3: Mix the metal powders of the components weighed in Step 2 and heat them for drying to obtain the flux cored powder. Step 4: Wrap the flux cored powder in the TA1 strip processed in Step 1 to make a semi-finished high-entropy alloy flux cored wire. Step 5: Pass the semi-finished high-entropy alloy flux cored wire obtained in Step 4 through a multi-pass cold drawing and reducing wire drawing die to obtain the final high-entropy alloy flux cored wire.

[0034] Specifically, Step 1 is as follows: First, clean the TA1 strip with a mixed solution of NaOH and acetone, then use deionized water and anhydrous ethanol solution to wash away the residual mixed solution, and then ultrasonically clean it with a mixed aqueous solution of HF and HNO 3 After cleaning, dry it to obtain a clean TA1 strip.

[0035] In the mixed solution of NaOH and acetone, the mass fraction of NaOH is 25% and the mass fraction of acetone is 75%. In the mixed aqueous solution of HF and HNO 3 the mass fraction of HF is 10%, and the mass fraction of HNO 3 is 30%, and the rest is water. The ultrasonic cleaning time is 8 - 10 min, and the ultrasonic frequency is 30 - 35 kHz.

[0036] Specifically, Step 3 is as follows: Mix the metal powders of the components weighed in Step 2 and heat them for drying, and then put the dried powder into a mixer for dry mixing. After the powder is fully mixed, the flux cored powder is obtained.

[0037] In Step 4, use a flux cored wire making machine to wrap the flux cored powder uniformly mixed in Step 3 in the TA1 strip at a powder filling rate of 30 wt% - 40 wt%, and use a forming machine to close the TA1 strip to obtain a semi-finished high-entropy alloy flux cored wire with a diameter of 2.1 mm.

[0038] Specifically, Step 5 is as follows: Pass the semi-finished high-entropy alloy flux cored wire with a diameter of 2.1 mm through wire drawing dies with diameters of 2.0 mm, 1.9 mm, 1.8 mm, 1.7 mm, 1.6 mm, 1.5 mm, 1.42 mm, and 1.2 mm in sequence to finally obtain a high-entropy alloy flux cored wire with a diameter of 1.2 mm.

[0039] Then wipe the oil stains on the wire with a cotton cloth dipped in anhydrous ethanol, and finally straighten the wire through a wire drawing machine, coil it into a disk, and seal and package it as a finished product.

[0040] Example 3 Application of the high-entropy alloy flux-cored wire of the present invention: The high-entropy alloy flux-cored wire prepared in Example 2 is used to prepare a wear-resistant coating on the surface of TC4 titanium alloy. Specifically, the high-entropy alloy flux-cored wire is used for cladding on the surface of TC4 titanium alloy. The cladding process is as follows: Tungsten inert gas welding is adopted, the welding current is 150 - 170 A, the voltage is 15 - 25 V, the welding speed is 15 cm / min, and the shielding gas is pure argon.

[0041] The tungsten inert gas welding (TIG) adopted in the present invention has the advantages of low cost, high process flexibility and large-scale production compared with the laser cladding method. Compared with surface thermal spraying, the high-entropy alloy cladding layer obtained by TIG welding has good bonding performance with the TC4 titanium alloy substrate and higher bonding strength. In the field of shipbuilding industry which requires high bonding strength and large-scale production, TIG welding has better application potential compared with the above two methods.

[0042] By using TIG welding in the present invention, the width of the molten pool can be flexibly controlled by adjusting the welding torch angle and travel speed. Laser cladding has strict requirements on the fluidity and particle size distribution of powders / wires (for example, powders need to be 15 - 150 μm). It is difficult to clad high reflectivity materials. TIG welding can be adapted to a wider range of filler materials (including coated electrodes, solid wires, etc.) and has better adaptability to high reflectivity metals.

[0043] Example 4 On the basis of Example 3, the high-entropy alloy flux-cored wire is prepared according to the following steps: Step 1: Prepare a mixed solution of NaOH and acetone, use it to thoroughly clean the TA1 strip, then clean it with clean water, and finally clean it with an ultrasonic cleaner. The cleaning solution is a mixed aqueous solution of HF and HNO 3 After cleaning, it is dried to obtain a clean TA1 strip; Among them, the mass fraction of NaOH in the mixed solution of NaOH and acetone used is 25%, and the mass fraction of acetone is 75%. The mass fraction of HF in the mixed aqueous solution of HF and HNO 3 is 10%, and the mass fraction of HNO 3 is 30%. Ultrasonic cleaning is carried out for 8 - 10 min, and the frequency is 30 - 35 kHz; Step 2: Take the following components according to atomic percentages: Ta: 20%, W: 30%, V: 22%, Mo: 28%. The sum of the atomic percentages of the above components is 100%. When taking, convert the above atomic percentages into mass percentages and weigh various metal powders according to the mass percentages; the particle size of each raw material powder is not greater than 124 μm; Step 3: Dry-mix the heated raw material powders in Step 2 in a mixer and mix them evenly to obtain the flux powder; Step 4: Wrap the flux powder after being uniformly mixed in Step 3 with TA1 tape by a flux-cored wire making machine, and use a forming machine to close the TA1 tape to obtain a flux-cored wire precursor of high-entropy alloy with a diameter of 2.1 mm; Step 5: Pass the flux-cored wire precursor of high-entropy alloy with a diameter of 2.1 mm obtained in Step 4 successively through cold drawing and reducing wire drawing dies with diameters of 2.0 mm, 1.9 mm, 1.8 mm, 1.7 mm, 1.6 mm, 1.5 mm, 1.42 mm, and 1.2 mm to obtain a wire with a diameter of 1.2 mm; Step 6: Wipe the oil stains on the wire with a cotton cloth dipped in anhydrous ethanol, and finally straighten the wire, coil it into a disk, and seal and package it by a wire drawing machine.

[0044] The flux-cored wire of high-entropy alloy prepared in Example 4 is used for cladding on the surface of TC4 titanium alloy. The process is as follows: tungsten inert gas welding (TIG) is adopted, the welding current is 170 A, the voltage is 15 - 20 V, the welding speed is 15 cm / min, and pure argon is selected as the shielding gas. When using this wire for welding, the arc is stable, the cladding layer is beautifully formed, and there are no defects such as pores, inclusions, cracks, and oxidation. In the friction and wear experiment of the high-entropy alloy coating, the selected parameters are motor frequency 6.25 hz, load 15 N, rotation speed 180 r / min, and friction 40 min. Under the condition that the counterface layer is quenched 45 steel, the wear amount is 2.3 mg. In the microhardness test, the maximum hardness can reach 550 HV 0.5 , its hardness is increased by 1.61 times compared with the base metal, and it has excellent wear resistance, meeting the usage requirements.

[0045] Example 5 Based on Example 3, the flux-cored wire of high-entropy alloy is prepared according to the following steps: Step 1: First, clean the TA1 tape with a mixed solution of NaOH and acetone, wash it with clean water after cleaning, and then ultrasonically clean it with a mixed aqueous solution of HF and HNO 3 to obtain the cleaned TA1 tape; In Step 1, the mass fraction of NaOH in the mixed solution of NaOH and acetone used is 25%, and the mass fraction of acetone is 75%. In the mixed aqueous solution of HF and HNO 3 , the mass fraction of HF is 10%, and the mass fraction of HNO 3 is 30%. Ultrasonic cleaning is carried out for 8 - 10 min, and the frequency is 30 - 35 kHz; Step 2: Prepare according to atomic percentages, and the total atomic percentage is 100%, where Ta: 20%, W: 30%, V: 24%, Mo: 26%. Convert the above atomic percentages into mass percentages, and weigh various metal powders according to the mass percentages; the particle size of each raw material powder is not greater than 124 μm.

[0046] Step 3: Dry mix the raw material powders after heating in Step 2 in a mixer until evenly mixed to obtain the flux cored powder; Step 4: Wrap the flux cored powder evenly mixed in Step 3 with TA1 tape using a flux cored wire making machine, and close the TA1 tape using a forming machine to obtain a precursor of a high entropy alloy flux cored wire with a diameter of 2.1 mm; Step 5: Pass the precursor of the high entropy alloy flux cored wire with a diameter of 2.1 mm obtained in Step 4 successively through cold drawing and reducing wire drawing dies with diameters of 2.0 mm, 1.9 mm, 1.8 mm, 1.7 mm, 1.6 mm, 1.5 mm, 1.42 mm, and 1.2 mm to obtain a wire with a diameter of 1.2 mm; Step 6: Wipe the oil stains on the wire with a cotton cloth dipped in acetone or absolute ethanol, and finally straighten the wire, coil it into a disk, and perform sealed packaging using a wire drawing machine.

[0047] The high entropy alloy flux cored wire prepared in Example 5 is used for cladding on the surface of TC4 titanium alloy. The process is as follows: Tungsten inert gas shielded welding (TIG) is used, the welding current is 150 A, the voltage is 20 - 25 V, the welding speed is 15 cm / min, and pure argon is used as the shielding gas. When welding with this wire, the arc is stable, the cladding layer has a beautiful shape, and there are no defects such as pores, cracks, inclusions, and oxidation. In the friction and wear experiment of the high entropy alloy coating, the selected parameters are a motor frequency of 6.25 hz, a load of 15 N, a rotation speed of 180 r / min, and a friction time of 40 min. Under the condition that the counterface layer is quenched 45 steel, the wear amount is 1.8 mg. In the microhardness test, the maximum hardness can reach 575 HV 0.5 Its hardness is increased by 1.68 times compared with the base material, and it has excellent wear resistance, meeting the usage requirements. Example 6 Based on Example 3, prepare the high entropy alloy flux cored wire according to the following steps: Step 1: First, clean the TA1 tape with a mixed solution of NaOH and acetone, then wash it with clean water, and then perform ultrasonic cleaning with a mixed aqueous solution of HF and HNO 3 to obtain the cleaned TA1 tape; In Step 1, the mass fraction of NaOH in the mixed solution of NaOH and acetone used is 25%, and the mass fraction of acetone is 75%. In the mixed aqueous solution of HF and HNO 3 the mass fraction of HF is 10%, and the mass fraction of HNO 3 is 30%. The ultrasonic cleaning is carried out for 8 - 10 min at a frequency of 30 - 35 kHz; Step 2: Prepare according to atomic percentages. The total atomic percentage is 100%, among which Ta: 20%, W: 30%, V: 26%, and Mo: 24%. Convert the above atomic percentages into mass percentages and weigh various metal powders according to the mass percentages. In Step 2, the particle size of each raw material powder is not greater than 124 μm.

[0048] Step 3: Dry-mix the heated raw material powders in Step 2 in a mixer, mix them evenly to obtain the flux-cored powder. Step 4: Wrap the flux-cored powder evenly mixed in Step 3 with TA1 tape through a flux-cored wire making machine, and use a forming machine to close the TA1 tape to obtain a precursor of a high-entropy alloy flux-cored wire with a diameter of 2.1 mm. Step 5: Pass the precursor of the high-entropy alloy flux-cored wire with a diameter of 2.1 mm obtained in Step 4 successively through cold-drawing and reducing wire drawing dies with diameters of 2.0 mm, 1.9 mm, 1.8 mm, 1.7 mm, 1.6 mm, 1.5 mm, 1.42 mm, and 1.2 mm to obtain a wire with a diameter of 1.2 mm. Step 6: Wipe the oil stains on the wire with a cotton cloth dipped in anhydrous ethanol, and finally straighten the wire, coil it into a disk, and seal and package it through a wire drawing machine.

[0049] The refractory high-entropy alloy flux-cored wire prepared in Example 6 is used for cladding on the surface of TC4 titanium alloy. The process is as follows: tungsten inert gas shielded arc welding (TIG) is adopted, the welding current is 150 A, the voltage is 20 - 25 V, the welding speed is 15 cm / min, and pure argon is selected as the shielding gas. When welding with this wire, the arc is stable, the cladding layer has a beautiful shape, and there are no defects such as pores, cracks, inclusions, and oxidation. Under the conditions that the parameters selected for the friction and wear experiment of the obtained refractory high-entropy alloy coating are motor frequency 6.25 hz, load 15 N, rotation speed 180 r / min, and friction 40 min, and the counterface layer is quenched 45 steel, the wear amount is 1.7 mg. In the microhardness test, the maximum hardness can reach 600 HV 0.5 , its hardness is increased by 1.82 times compared with the base metal, and it has excellent wear resistance, meeting the usage requirements.

[0050] Example 7 On the basis of Example 3, prepare a high-entropy alloy flux-cored wire according to the following steps: Step 1: First, clean the TA1 tape with a mixed solution of NaOH and acetone. After cleaning, wash it with clean water, and then ultrasonically clean it with a mixed aqueous solution of HF and HNO 3 to obtain the cleaned TA1 tape. In Step 1, the mass fraction of NaOH in the mixed solution of NaOH and acetone used is 25%, and the mass fraction of acetone is 75%. HF and HNO3 In the mixed aqueous solution, the mass fraction of HF is 10%, and the mass fraction of HNO 3 is 30%. Ultrasonic cleaning is performed for 8 - 10 min at a frequency of 30 - 35 kHz; Step 2: Prepare according to atomic percentages. The total atomic percentage is 100%, where Ta: 20%, W: 30%, V: 28%, and Mo: 22%. Convert the above atomic percentages into mass percentages and weigh various metal powders according to the mass percentages; the particle size of each raw material powder is not greater than 124 μm.

[0051] Step 3: Dry - mix the heated raw material powders from Step 2 in a mixer until evenly mixed to obtain the flux - cored powder; Step 4: Wrap the flux - cored powder evenly mixed in Step 3 with TA1 tape through a flux - cored wire making machine, and use a forming machine to close the TA1 tape to obtain a precursor of a high - entropy alloy flux - cored wire with a diameter of 2.1 mm; Step 5: Pass the precursor of the high - entropy alloy flux - cored wire with a diameter of 2.1 mm obtained in Step 4 successively through cold - drawn reducing dies with diameters of 2.0 mm, 1.9 mm, 1.8 mm, 1.7 mm, 1.6 mm, 1.5 mm, 1.42 mm, and 1.2 mm to obtain a wire with a diameter of 1.2 mm; Step 6: Wipe the oil stains on the wire with a cotton cloth dipped in anhydrous ethanol, and finally straighten the wire through a wire drawing machine, coil it into a disk, and seal and package it.

[0052] The high - entropy alloy flux - cored wire prepared in Example 7 is cladded on the surface of TC4 titanium alloy. The process is as follows: tungsten inert gas welding (TIG) is used, the welding current is 150 A, the voltage is 20 - 25 V, the welding speed is 15 cm / min, and the shielding gas is pure argon. When welding with this wire, the arc is stable, the cladding layer has a beautiful shape, and there are no defects such as pores, cracks, inclusions, and oxidation. Under the conditions of the friction and wear experiment with parameters of motor frequency 6.25 hz, load 15 N, rotation speed 180 r / min, and friction for 40 min, and the counter - face layer selected as quenched 45 steel, the wear amount is 1.6 mg. In the micro - hardness test, the maximum hardness can reach 630 HV 0.5 , and its hardness is 2.15 times higher than that of the base material, with excellent wear - resistant performance, meeting the usage requirements.

[0053] In Examples 4 - 7, as the proportion of vanadium element increases, the friction and wear performance and hardness of the cladding layer made of the obtained flux - cored powder gradually increase. Therefore, the metallographic structure of the cladding layer obtained in Example 7 is observed, as Figure 1-2 shown, Figure 1 is the top of the cladding layer, Figure 2 is the combined diagram of the lower part of the cladding layer and the substrate. FromFigure 1 It can be seen that the upper part of the coating is mainly composed of equiaxed grains, with a small amount of columnar grains. The surface layer of the cladding layer is composed of small columnar crystals and many fine grains without a specific growth direction. This is because the angle between the cladding direction and the columnar grains is very small. The formation of fine grains without a specific growth direction can be attributed to impurities floating on the equiaxed grains. These fine grains are evenly distributed within the grain boundaries and in the grain plane gaps, pinning the slip of dislocations, which is one of the key factors for the improvement of the strength of the cladding layer. From Figure 2 it can be known that the lower part of the layer cladding layer is composed of fine and uniform cellular grains and equiaxed grains. The size of the cellular grains is smaller than that of the columnar grain size, and the grain boundary density is higher, which more significantly hinders the dislocation, and the regular arrangement of the cellular grains can effectively slow down the crack propagation and increase the toughness of the cladding layer. From Figure 2 it can be seen that the bonding between the cladding layer and the substrate is good, and there are no obvious grain plane defects between the substrate and the cladding layer, which also proves the good forming performance of TIG welding.

Claims

1. A high entropy alloy flux-cored welding wire for preparing a wear-resistant coating on the surface of TC4 titanium alloy, characterized in that: The invention comprises a flux core and a welding skin, wherein the flux core is composed of the following components according to atomic percentage: Ta: 20%, W: 30%, V: 22-28%, Mo: 22-28%, and the sum of the atomic percentages of the above components is 100%.

2. The high entropy alloy flux-cored welding wire for preparing a wear-resistant coating on the surface of TC4 titanium alloy according to claim 1, characterized in that: The solder strip is TA1 tape.

3. The high entropy alloy flux-cored welding wire for preparing a wear-resistant coating on the surface of TC4 titanium alloy according to claim 2, characterized in that: The welding skin is composed of the following components in mass percentage: Fe: 0.15%, O: 0.12%, C: 0.08%, N: 0.03%, H: 0.015%, and Ti is the balance.

4. The high entropy alloy flux-cored welding wire for preparing a wear-resistant coating on the surface of TC4 titanium alloy according to claim 1, characterized in that: The powder filling rate of the flux core in the flux cored welding wire is 30wt%-40wt%.

5. A method for preparing a high entropy alloy flux-cored welding wire, characterized in that: The preparation of the high entropy alloy flux-cored welding wire for preparing a wear-resistant coating on the surface of TC4 titanium alloy as claimed in claim 4 is specifically carried out according to the following steps: Step 1, ultrasonically clean and dry the solder skin TA1 tape; Step 2, weigh the following components according to atomic percentage: Ta: 20%, W: 30%, V: 22-28%, Mo: 22-28%, the sum of the atomic percentages of the above components is 100%; Step 3, mixing the metal powders of the components weighed in step 2 and heating and drying them to obtain a core powder; Step 4, wrapping the flux core powder in the TA1 tape processed in step 1 to prepare a semi-finished high entropy alloy flux cored welding wire; Step 5, subjecting the high entropy alloy flux-cored welding wire obtained in step 4 to multiple cold drawing and diameter reducing wire drawing dies to obtain the final high entropy alloy flux-cored welding wire.

6. The method for preparing a high entropy alloy flux-cored welding wire according to claim 5, characterized in that: The step 1 is specifically as follows: the solder-covered TA1 tape is first cleaned with a mixed solution of NaOH and acetone, and then the residual mixed solution is cleaned with deionized water and anhydrous ethanol solution, and then ultrasonically cleaned with a mixed aqueous solution of HF and HNO3, and then dried after cleaning to obtain a clean TA1 tape.

7. The method for preparing a high entropy alloy flux-cored welding wire according to claim 6, characterized in that: The mass fraction of NaOH in the mixed solution of NaOH and acetone is 25%, the mass fraction of acetone is 75%, the mass fraction of HF in the mixed aqueous solution of HF and HNO3 is 10%, the mass fraction of HNO3 is 30%, and the rest is water, the ultrasonic cleaning time is 8-10 minutes, and the ultrasonic frequency is 30-35kHz; The metal powders of each component weighed in step 2 are mixed and heated to dry, and then the dried powders are put into a mixer for dry mixing. When the powders are fully mixed, the core powder is obtained.

8. The method for preparing a high entropy alloy flux-cored welding wire according to claim 7, characterized in that: In the step 4, a flux-cored wire making machine is used to wrap the flux-cored powder uniformly mixed in step 3 in a TA1 belt according to a powder filling rate of 30wt%~40wt%, and a forming machine is used to close the TA1 belt to obtain a high-entropy alloy flux-cored welding wire semi-finished product with a diameter of 2.1mm.

9. The method for preparing a high entropy alloy flux-cored welding wire according to claim 8, characterized in that: The step 5 is specifically as follows: passing the semi-finished high entropy alloy flux-cored welding wire with a diameter of 2.1 mm through wire drawing dies with diameters of 2.0 mm, 1.9 mm, 1.8 mm, 1.7 mm, 1.6 mm, 1.5 mm, 1.42 mm, and 1.2 mm in sequence to finally obtain a high entropy alloy flux-cored welding wire with a diameter of 1.2 mm.

10. Application of high entropy alloy flux-cored welding wire, characterized in that: The high entropy alloy flux-cored welding wire prepared according to claim 9 is used to prepare a wear-resistant coating on the surface of TC4 titanium alloy, specifically: the high entropy alloy flux-cored welding wire is used to clad the surface of TC4 titanium alloy, and the cladding process is: tungsten electrode non-melting inert gas shielded welding is adopted, the welding current is 150-170A, the voltage is 15~25V, the welding speed is 15cm / min, and the shielding gas is pure argon.

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