A eutectic high-entropy alloy material, a preparation method and application thereof

Abstract

The application belongs to the technical field of adhesive layer materials, and particularly relates to a eutectic high-entropy alloy material and a preparation method and application thereof. The eutectic high-entropy alloy material provided by the application is specifically a NiCoCrAlTiTaZr alloy, which comprises the following elements with atomic percentage: 2-8 at.% Zr, 2-8 at.% Ta, 2-8 at.% Ti, 10-20 at.% Al, 10-20 at.% Cr, 10-20 at.% Co, and the balance of Ni. The high content of Al and Cr in the NiCoCrAlTiTaZr alloy helps to improve the oxidation resistance, the high content of Ti, Ta and Zr is innovatively introduced to improve the formation ability of the eutectic structure, the phase size is refined, and the thermal corrosion resistance can be greatly improved. The uniform distribution of the ultra-fine eutectic structure of the alloy ensures the uniform distribution of each element, and is also beneficial to fully exert the thermal corrosion resistance characteristics of the elements.

Description

Technical Field

[0001] This invention belongs to the field of adhesive layer material technology, specifically relating to a eutectic high-entropy alloy material, its preparation method, and its application. Background Technology

[0002] Thermal barrier coatings are primarily used for high-temperature thermal protection of hot-end components (including combustion chambers and blades) in gas turbines and aero engines. The outer layer is a ceramic layer, mainly serving as insulation and cooling; the inner layer is an adhesive layer that provides both oxidation and thermal corrosion resistance. The adhesive layer is considered the core of the thermal barrier coating, directly determining its service performance and lifespan.

[0003] As a mainstream binder material, NiCoCrAlY exhibits relatively balanced oxidation and corrosion resistance. However, in the high-temperature and high-salt service environment of the ocean, the oxide film formed on traditional NiCoCrAlY will undergo severe dissolution and peeling, leading to rapid coating failure and making it difficult to maintain stable service in extremely harsh environments for a long time. Therefore, it cannot meet the stringent requirements of future marine gas turbines and carrier-based aircraft for material service environments. Summary of the Invention

[0004] This invention proposes a eutectic high-entropy alloy material, its preparation method, and its application. This eutectic alloy specifically improves the oxidation resistance and hot corrosion resistance of the bonding layer.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a eutectic high-entropy alloy material, wherein the eutectic high-entropy alloy material is a NiCoCrAlTiTaZr alloy, and the NiCoCrAlTiTaZr alloy comprises the following elements in atomic percentages: 2~8 at.% Zr; 2~8 at.% Ta; 2~8 at.% Ti; 10~20 at.% Al; 10~20 at.% Cr; 10~20 at.% Co; with the balance being Ni.

[0006] In some embodiments of the present invention, the NiCoCrAlTiTaZr alloy comprises 2 to 8 at.% Ti, preferably 5 to 8 at.% Ti, based on atomic percentages. The NiCoCrAlTiTaZr alloy comprises 2~8 at.% Zr, preferably 5~8 at.%; The NiCoCrAlTiTaZr alloy comprises 2~8 at.% Ta, preferably 5~8 at.%; This invention improves the hot corrosion resistance of the alloy by adding a higher content of Ti, Ta and Zr to the eutectic alloy. The TiO2, TaO2 and ZrO2 generated by oxidation have good resistance to sodium sulfate and sodium chloride.

[0007] The NiCoCrAlTiTaZr alloy comprises 10~20 at.% Al, preferably 15~20 at.%; The NiCoCrAlTiTaZr alloy comprises 10~20 at.% Cr, preferably 15~20 at.%; This invention improves the oxidation resistance of eutectic alloys by adding high contents of Al and Cr to the alloys and oxidizing them to form Al2O3.

[0008] The NiCoCrAlTiTaZr alloy comprises 10~20 at.% Co, preferably 15~20 at.%; The NiCoCrAlTiTaZr alloy also includes Ni as the balance.

[0009] Under the above elemental ratio, the alloy exhibits a high-temperature stable, uniform, and fine two-phase structure. The ultrafine eutectic structure promotes the uniform distribution of alloying elements, allowing Ti, Ta, Zr, Al, and Cr to exert their respective elemental characteristics and improving the alloy's hot corrosion and oxidation resistance.

[0010] Furthermore, the NiCoCrAlTiTaZr alloy has a eutectic structure, comprising a NiCoCrAlTi-rich phase as the matrix and a TaZr-rich phase as the precipitated phase.

[0011] Furthermore, the oxide film produced by the NiCoCrAlTiTaZr alloy under the hot corrosion conditions of coating with a mixture of Na2SO4 and 25 wt% NaCl at 900℃ does not peel off; wherein the oxide film is a complete and uniform Al2O3 film containing Ti, Ta, Zr and Cr.

[0012] The present invention also provides a method for preparing the above-mentioned eutectic high-entropy alloy material, the method comprising: converting the atomic ratio of the NiCoCrAlTiTaZr alloy into a mass ratio and then batching and mixing the raw materials to obtain a mixed raw material; sequentially melting and solidifying the mixed raw material to obtain a primary eutectic alloy; and repeatedly melting and solidifying the primary eutectic alloy to obtain the eutectic high-entropy alloy material.

[0013] Furthermore, the mixed raw materials include raw materials Al, Ni, Co, Cr, Ti, Ta, and Zr stacked sequentially from bottom to top; wherein raw material Al is Al metal, raw material Ni is Ni metal, raw material Co is Co metal, raw material Cr is Cr metal, raw material Ti is Ti metal, raw material Ta is Ta metal, and raw material Zr is Zr metal; the purity of Al metal, Ni metal, Co metal, Cr metal, Ti metal, Ta metal, and Zr metal is all above 99.5%, and the particle size is 2~5mm.

[0014] It can be seen that the raw materials selected in this invention are preferably metals of the corresponding elements, and the purity of the metal is preferably 99.5% or higher, more preferably 99.6% to 99.9%. In this invention, the raw materials of each element in the NiCoCrAlTiTaZr alloy are preferably particles, and the particle size is preferably 2 to 5 mm, more preferably 3 to 4 mm.

[0015] In addition, in order to give the mixed raw materials the above-mentioned structure, raw materials Al, Ni, Co, Cr, Ti, Ta and Zr can be laid in order from bottom to top during the mixing stage.

[0016] In some embodiments of the present invention, the pre-mixing step preferably further includes: sequentially washing and drying the raw materials. In the present invention, the washing preferably includes sequentially performing a first ultrasonic cleaning and a second ultrasonic cleaning. In the present invention, the solvent used for the first ultrasonic cleaning is preferably water, preferably deionized water; the solvent used for the second ultrasonic cleaning is preferably acetone. In the present invention, the power of the first and second ultrasonic cleanings is preferably greater than 100W; the time for the first and second ultrasonic cleanings is preferably 8-12 min, more preferably 10-11 min. In the present invention, the drying is preferably oven drying; the drying temperature is preferably 50-100℃, more preferably 60-80℃; the drying time is preferably 10-40 min, more preferably 20-30 min.

[0017] Furthermore, the process of smelting includes placing an oxygen scavenger inside the smelting equipment; the oxygen scavenger includes titanium blocks or titanium sheets.

[0018] In some embodiments of the present invention, the process of smelting preferably includes placing an oxygen scavenger inside the smelting equipment; the oxygen scavenger preferably comprises titanium blocks or titanium sheets, more preferably titanium sheets. In the present invention, the oxygen scavenger is preferably placed in a pre-reserved crucible in the smelting equipment, which facilitates the adsorption of residual oxygen in the protective atmosphere after the oxygen scavenger melts, thereby reducing oxidation during the alloy smelting process. In the present invention, the melting time of the oxygen scavenger is preferably 3-4 minutes. The present invention does not have a special limitation on the amount of oxygen scavenger used, as long as it can remove residual oxygen in the protective atmosphere. The present invention has no special requirements for the smelting equipment; conventional smelting equipment can be used. In embodiments of the present invention, the smelting equipment is a smelting furnace.

[0019] Furthermore, the melting is carried out under a protective atmosphere; the melting temperature is 1500~2000℃.

[0020] In some embodiments of the present invention, the melting temperature is preferably 1500~2000℃, more preferably 1700~1850℃. In the present invention, the melting is preferably carried out under a protective atmosphere; the protective atmosphere preferably includes argon. In the present invention, the melting is preferably non-consumable vacuum arc melting. In embodiments of the present invention, the protective atmosphere is formed by: evacuating the arc melting furnace and then filling it with a protective gas; the vacuum degree of the evacuation is 3×10⁻⁶. -3 ~5×10 -3 Pa; the pressure after filling with protective gas is 0~100Pa and not 0. In this invention, the current of the non-consumable vacuum arc melting is preferably 58~62A, more preferably 60A.

[0021] In some embodiments of the present invention, stirring is preferably performed after the raw materials are melted, and the stirring is preferably electromagnetic stirring; the electromagnetic stirring time is preferably 40-80 seconds, more preferably 50-60 seconds. The present invention achieves uniform mixing of the raw materials under the action of electromagnetic stirring. In the present invention, the melting time is the sum of the melting time and the stirring time.

[0022] In this invention, the solidification is preferably carried out in a water-cooled copper crucible. This invention does not have special requirements for the solidification process; conventional methods in the art can be used.

[0023] Furthermore, the repetition is performed 3 to 6 times.

[0024] After obtaining the primary eutectic alloy, the present invention repeatedly melts and solidifies the primary eutectic alloy to obtain the eutectic alloy. In the present invention, before repeating the melting and solidification, it is preferable to flip the solid obtained from the previous solidification, and the flipping is preferably performed using a robotic arm. In the present invention, the number of repetitions is preferably 3 to 6 times, more preferably 4 to 5 times.

[0025] The present invention also provides the application of the above-mentioned eutectic high-entropy alloy material as a bonding layer material.

[0026] Compared with the prior art, the technical solution provided by the present invention has at least the following advantages: This invention provides a eutectic high-entropy alloy material, its preparation method, and its applications. Specifically, the eutectic high-entropy alloy material is a NiCoCrAlTiTaZr alloy, with a NiCoCrAlTi-rich phase as the matrix and a TaZr-rich phase as the precipitated phase in the eutectic. The formed eutectic structure promotes the uniform distribution of key elements such as Al, Ti, Ta, and Zr. During oxidation and corrosion, protective TiO2, TaO2, ZrO2, and Al2O3 are generated. Al2O3 ensures oxidation resistance, while TiO2, TaO2, and ZrO2 enhance corrosion resistance. Using this NiCoCrAlTiTaZr alloy as a binder layer material provides excellent resistance to hot corrosion and also exhibits certain oxidation resistance at high temperatures. Attached Figure Description

[0027] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments, and unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0028] Figure 1 The scanning electron microscope backscattered electron image of the NiCoCrAlTiTaZr alloy provided in Example 1 of this invention; Figure 2 The cross-sectional morphology of the NiCoCrAlTiTaZr alloy sample provided in Example 1 of this invention after 240 h of hot corrosion; Figure 3 The cross-sectional morphology of the NiCoCrAlTiTaZr alloy sample provided in Example 1 of this invention after high-temperature oxidation for 500 hours. Detailed Implementation

[0029] The present invention will now be described in detail with reference to specific embodiments.

[0030] Example 1 Aluminum particles, cobalt particles, chromium particles, nickel particles, titanium particles, tantalum particles, and zirconium particles with a purity of 99.9% and an average particle size of 3 mm were ultrasonically cleaned for 10 min with deionized water as the solvent and a power of 120 W, and then ultrasonically cleaned for 10 min with acetone as the solvent and a power of 120 W. They were then dried at 80℃ for 20 min before use. Al: 9.1 g (accounting for 20 at.% of the atomic percentage of the NiCoCrAlTiTaZr alloy); Ni: 19.7 g (20 at.% of the atomic percentage of the NiCoCrAlTiTaZr alloy); Co: 19.8g (accounting for 20 at.% of the atomic percentage of the NiCoCrAlTiTaZr alloy); Cr: 17.5 g (20 at.% of the atomic percentage of the NiCoCrAlTiTaZr alloy); Ti: 6.4 g (8 at.% of the atomic percentage of the NiCoCrAlTiTaZr alloy); Ta: 18.3 g (accounting for 6 at.% of the atomic percentage of the NiCoCrAlTiTaZr alloy); Zr: 9.2 g (accounting for 6 at.% of the atomic percentage of the NiCoCrAlTiTaZr alloy).

[0031] Al, Ni, Co, Cr, Ti, Ta, and Zr are laid in the electric arc melting furnace in the order from bottom to top; after placing the titanium sheet in the crucible reserved in the melting furnace, the vacuum electric arc melting furnace is evacuated to 3×10⁻⁶. -3 Pa, argon gas is introduced to 5 Pa; the titanium sheet is melted by arc ignition for 3 min to adsorb residual oxygen in the protective atmosphere; under argon protection, non-consumable vacuum arc melting is carried out for 1 min at a current of 60 A and a temperature of 1600 °C. After the raw material is fully melted, electromagnetic stirring is turned on and kept for 60 s. The melt is then solidified in a water-cooled copper crucible and the ingot is flipped by a robot. The melting and solidification are repeated 5 times to obtain 100 g of eutectic NiCoCrAlTiTaZr alloy button ingot.

[0032] The resistance to molten salt hot corrosion of the NiCoCrAlTiTaZr alloy prepared in Example 1 was tested according to the following steps: (1) In Example 1, the NiCoCrAlTiTaZr eutectic alloy is composed of a NiCoCrAlTi matrix phase and a TaZr-rich precipitate phase, such as Figure 1 As shown. The eutectic high-entropy alloy of Example 1 was cut into 10mm×10mm×2mm test pieces, and polished with 240#, 600# and 1000# sandpaper in sequence. After that, it was ultrasonically cleaned with deionized water and acetone for 10 min in sequence and then dried at 80℃ for 20 min. (2) Coat the surface of the NiCoCrAlTiTaZr sample from (1) with 2.0 mg ± 0.1 mg / cm 2A mixed salt of Na₂SO₄ + 25 wt% NaCl was placed directly in a muffle furnace and subjected to hot corrosion behavior testing at 900℃ in an atmospheric environment. Samples were removed every 20 hours, cleaned with plasma water, weighed, and then recoated with the mixed salt for the next hot corrosion test cycle. Experimental results are shown below. Figure 2 The NiCoCrAlTiTaZr specimens showed a uniform and continuous oxide film on their surface, which remained intact in the corrosive salts, indicating that the alloy has excellent resistance to hot corrosion.

[0033] (3) The NiCoCrAlTiTaZr sample from (1) was placed directly in a muffle furnace and tested for high-temperature oxidation resistance at 1200℃ in an atmospheric environment. Figure 3 This is a cross-sectional image of the alloy after 500 hours of oxidation. The oxide film on the NiCoCrAlTiTaZr alloy did not peel off after 500 hours of oxidation at 1200℃, indicating that the alloy has excellent oxidation resistance.

[0034] Example 2 Aluminum particles, cobalt particles, chromium particles, nickel particles, titanium particles, tantalum particles, and zirconium particles with a purity of 99.9% and an average particle size of 3 mm were ultrasonically cleaned for 10 min with deionized water as the solvent and a power of 120 W, and then ultrasonically cleaned for 10 min with acetone as the solvent and a power of 120 W. They were then dried at 80℃ for 20 min before use. Al: 6.7 g (accounting for 15 at.% of the atomic percentage of the NiCoCrAlTiTaZr alloy); Ni: 39.0 g (40 at.% of the atomic percentage of the NiCoCrAlTiTaZr alloy); Co: 14.7 g (accounting for 15 at.% of the atomic percentage of the NiCoCrAlTiTaZr alloy); Cr: 13.0 g (accounting for 15 at.% of the atomic percentage of the NiCoCrAlTiTaZr alloy); Ti: 4.0 g (5 at.% of the atomic percentage of the NiCoCrAlTiTaZr alloy); Ta: 15.0 g (5 at.% of the atomic percentage of the NiCoCrAlTiTaZr alloy); Zr: 7.6 g (accounting for 5 at.% of the atomic percentage of the NiCoCrAlTiTaZr alloy).

[0035] Al, Ni, Co, Cr, Ti, Ta, and Zr are laid in the electric arc melting furnace in the order from bottom to top; after placing the titanium sheet in the crucible reserved in the melting furnace, the vacuum electric arc melting furnace is evacuated to 3×10⁻⁶.-3 Pa, argon gas is introduced to 5 Pa; the titanium sheet is melted by arc ignition for 3 min to adsorb residual oxygen in the protective atmosphere; under argon protection, non-consumable vacuum arc melting is carried out for 1 min at a current of 60 A and a temperature of 1600 °C. After the raw material is fully melted, electromagnetic stirring is turned on and kept for 60 s. The melt is then solidified in a water-cooled copper crucible and the ingot is flipped by a robot. The melting and solidification are repeated 5 times to obtain 100 g of eutectic NiCoCrAlTiTaZr alloy button ingot.

[0036] Example 3 Aluminum particles, cobalt particles, chromium particles, nickel particles, titanium particles, tantalum particles, and zirconium particles with a purity of 99.9% and an average particle size of 3 mm were ultrasonically cleaned for 10 min with deionized water as the solvent and a power of 120 W, and then ultrasonically cleaned for 10 min with acetone as the solvent and a power of 120 W. They were then dried at 80℃ for 20 min before use. Al: 4.7 g (accounting for 10 at.% of the atomic percentage of the NiCoCrAlTiTaZr alloy); Ni: 65.0 g (64 at.% of the atomic percentage of the NiCoCrAlTiTaZr alloy); Co: 10.2 g (accounting for 10 at.% of the atomic percentage of the NiCoCrAlTiTaZr alloy); Cr: 9.0 g (accounting for 10 at.% of the atomic percentage of the NiCoCrAlTiTaZr alloy); Ti: 1.7 g (accounting for 2 at.% of the atomic percentage of the NiCoCrAlTiTaZr alloy); Ta: 6.3 g (accounting for 2 at.% of the atomic percentage of the NiCoCrAlTiTaZr alloy); Zr: 3.2 g (accounting for 2 at.% of the atomic percentage of the NiCoCrAlTiTaZr alloy).

[0037] Al, Ni, Co, Cr, Ti, Ta, and Zr are laid in the electric arc melting furnace in the order from bottom to top; after placing the titanium sheet in the crucible reserved in the melting furnace, the vacuum electric arc melting furnace is evacuated to 3×10⁻⁶. -3Pa, argon gas is introduced to 5 Pa; the titanium sheet is melted by arc ignition for 3 min to adsorb residual oxygen in the protective atmosphere; under argon protection, non-consumable vacuum arc melting is carried out for 1 min at a current of 60 A and a temperature of 1600 °C. After the raw material is fully melted, electromagnetic stirring is turned on and kept for 60 s. The melt is then solidified in a water-cooled copper crucible and the ingot is flipped by a robot. The melting and solidification are repeated 5 times to obtain 100 g of eutectic NiCoCrAlTiTaZr alloy button ingot.

[0038] Those skilled in the art will understand that the above embodiments are specific examples of implementing the present invention, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of the present invention. Any person skilled in the art can make their own modifications and alterations without departing from the spirit and scope of the present invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A eutectic high-entropy alloy material, characterized in that, The eutectic high-entropy alloy material is a NiCoCrAlTiTaZr alloy, which comprises the following elements in atomic percentages: 2~8 at.% Zr; 2~8 at.% Ta; 2~8 at.% Ti; 10~20 at.% Al; 10~20 at.% Cr; 10~20 at.% Co; The balance is Ni.

2. The eutectic high-entropy alloy material according to claim 1, characterized in that, The NiCoCrAlTiTaZr alloy has a eutectic structure, comprising a NiCoCrAlTi-rich phase as the matrix and a TaZr-rich phase as the precipitated phase.

3. The eutectic high-entropy alloy material according to claim 1, characterized in that, The oxide film formed on the NiCoCrAlTiTaZr alloy under hot corrosion conditions of 900℃ coated with a mixture of Na2SO4 and 25 wt% NaCl does not peel off; wherein the oxide film is an Al2O3 film containing Ti, Ta, Zr and Cr.

4. A method for preparing a eutectic high-entropy alloy material according to any one of claims 1 to 3, characterized in that, The preparation method includes: After converting the atomic ratio of the NiCoCrAlTiTaZr alloy to the mass ratio, the raw materials are batched and mixed to obtain a mixed raw material; the mixed raw material is then melted and solidified sequentially to obtain a primary eutectic alloy. The primary eutectic alloy is repeatedly melted and solidified to obtain the eutectic high-entropy alloy material.

5. The method for preparing the eutectic high-entropy alloy material according to claim 4, characterized in that, The mixed raw materials include raw materials Al, Ni, Co, Cr, Ti, Ta and Zr stacked from bottom to top; Among them, raw material Al is Al metal, raw material Ni is Ni metal, raw material Co is Co metal, raw material Cr is Cr metal, raw material Ti is Ti metal, raw material Ta is Ta metal, and raw material Zr is Zr metal; the purity of Al metal, Ni metal, Co metal, Cr metal, Ti metal, Ta metal and Zr metal is all above 99.5%, and the particle size is 2~5mm.

6. The method for preparing the eutectic high-entropy alloy material according to claim 4, characterized in that, The melting was carried out under a protective atmosphere; The melting temperature is 1500~2000℃.

7. The method for preparing the eutectic high-entropy alloy material according to claim 6, characterized in that, The melting process specifically includes: after evacuating the vacuum, filling it with protective gas, and then melting the mixed raw materials at a temperature of 1500~2000℃ using a non-consumable vacuum arc melting method; The vacuum level of the vacuum pump is 3×10⁻⁶. -3 ~5×10 -3 Pa; the pressure after filling with protective gas is 0~100Pa and not 0; the pressure of the non-consumable vacuum arc melting is 58~62A.

8. The method for preparing the eutectic high-entropy alloy material according to claim 5, characterized in that, The process before smelting also includes placing an oxygen scavenger inside the smelting equipment; The oxygen scavenger includes titanium blocks or titanium sheets.

9. The method for preparing the eutectic high-entropy alloy material according to claim 5, characterized in that, The repetition is repeated 3 to 6 times.

10. The application of the eutectic high-entropy alloy material according to any one of claims 1 to 4 as a binder material.

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