An antioxidant nano-structured high-entropy alloy material and a preparation method and application thereof

Abstract

The application belongs to the technical field of coating materials, and particularly relates to an oxidation-resistant nano-structured high-entropy alloy material and a preparation method and application thereof. The oxidation-resistant nano-structured high-entropy alloy material is a NiCoCrAlMoNb alloy with a nano structure, and includes the following elements in atomic percentage: 18-23 at.% Al, 18-23 at.% Co, 18-23 at.% Cr, 8-12 at.% Mo, 8-12 at.% Nb, and the balance being Ni. The high content of Al and Cr in the NiCoCrAlMoNb alloy helps to improve the oxidation resistance, and the high content of the refractory elements Mo and Nb with large ion sizes is innovatively introduced to increase the lattice distortion of the alloy, so that the alloy forms a nano structure, promotes the growth of protective Al2O3, and can greatly improve the oxidation resistance. The nano structure of the alloy ensures the uniform distribution of the elements, and is also beneficial to further optimizing the oxidation resistance.

Description

Technical Field

[0001] This invention belongs to the field of coating materials technology, specifically relating to a high-entropy alloy material with an antioxidant nanostructure, its preparation method, and its application. Background Technology

[0002] Thermal barrier coatings are primarily used for high-temperature thermal protection of hot-end components (such as blades and combustion chambers) in aero-engines and gas turbines. Thermal barrier coatings typically have a two-layer structure, consisting of a top insulating ceramic layer and a bottom anti-oxidation bonding layer. The bonding layer forms a continuous, dense alumina film at high temperatures, which not only protects the hot-end components from oxidation by high-temperature combustion gases but also enhances the interfacial bonding performance of the coating.

[0003] MCrAlY (M = Ni, Co, or Ni + Co) is currently the most commonly used mainstream binder material. However, with the increasingly stringent service requirements of hot-end components, traditional NiCoCrAlY alloys, due to their rapid oxidation rate and tendency for the oxide film to peel off, are no longer sufficient to meet the temperature performance requirements of future engines and gas turbines. Therefore, there is an urgent need to develop binder materials with superior performance. Summary of the Invention

[0004] This invention provides a high-entropy alloy material with an antioxidant nanostructure, its preparation method, and its application. The high-entropy alloy material with an antioxidant nanostructure is a NiCoCrAlMoNb alloy with a nanostructure. Using the NiCoCrAlMoNb alloy as a binder layer material can improve the antioxidant properties of the binder layer.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a high-entropy alloy material with an antioxidant nanostructure, wherein the high-entropy alloy material with an antioxidant nanostructure is a NiCoCrAlMoNb alloy, and the NiCoCrAlMoNb alloy comprises the following elements in atomic percentages: Co18~23 at.%% Cr 18~23 at.%; Al18~23 at.%% Mo8~12 at.%% Nb8~12 at.%% Ni balance.

[0006] In some embodiments of the present invention, the NiCoCrAlMoNb alloy comprises 18~23 at.% Co, preferably 20~23 at.% Co, based on atomic percentages. The NiCoCrAlMoNb alloy comprises 18~23 at.% Cr, preferably 20~23 at.%; The NiCoCrAlMoNb alloy comprises 18~23 at.% Al, preferably 20~23 at.%.

[0007] The NiCoCrAlMoNb alloy comprises 8~12 at.% Mo, preferably 10~12 at.%. In this invention, the Mo can enhance the formation tendency of nanostructures.

[0008] The NiCoCrAlMoNb alloy comprises 8~12 at.% Nb, preferably 10~12 at.%. In this invention, the Nb can enhance the activity of Al and promote the formation of an alumina protective film.

[0009] Based on the above proportions, the NiCoCrAlMoNb alloy also includes Ni as the balance.

[0010] Furthermore, the NiCoCrAlMoNb alloy has a nanostructure, which includes a NiCoMo-rich phase as the matrix and a CrAlNb-rich phase as the precipitated phase.

[0011] This NiCoCrAlMoNb alloy contains high levels of Al and Cr, which helps improve its oxidation resistance. It also innovatively incorporates high levels of Mo and Nb, refractory elements with large ionic sizes, to increase lattice distortion and create a nanostructure. This nanostructure promotes the growth of protective Al₂O₃ during the coating application stage, thereby further enhancing its oxidation resistance. The nanostructure of this NiCoCrAlMoNb alloy ensures a uniform distribution of elements, which also facilitates further optimization of its oxidation resistance.

[0012] Furthermore, the nanostructure also includes a MoNb-rich phase as the precipitated phase.

[0013] The synergistic effect of refractory elements Mo and Nb with other elements forms a high-temperature stable nanostructure, which makes Mo, Nb, Al and other elements evenly distributed, giving full play to the functions of each element and improving the high-temperature oxidation resistance of the alloy.

[0014] Furthermore, after the NiCoCrAlMoNb alloy undergoes oxidation treatment at 1200℃ or below for no more than 500 hours, the oxide film formed on the surface is continuous, dense, and does not peel off.

[0015] The present invention also provides a method for preparing the above-mentioned high-entropy alloy material with antioxidant nanostructure. The method includes: converting the atomic ratio of the NiCoCrAlMoNb 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 an alloy material with a primary nanostructure; and repeatedly melting and solidifying the alloy material with the primary nanostructure to obtain the high-entropy alloy material with antioxidant nanostructure.

[0016] Furthermore, the mixed raw materials include raw materials Al, Ni, Co, Cr, Mo, and Nb 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 Mo is Mo metal, and raw material Nb is Nb metal; the purity of Al metal, Ni metal, Co metal, Cr metal, Mo metal, and Nb metal is all above 99.5%, and the particle size is 2~5mm.

[0017] 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 99.6-99.9%. In this invention, the raw materials of each element in the NiCoCrAlMoNb alloy are preferably particles, and the particle size is preferably 2-5 mm, more preferably 3-4 mm.

[0018] In addition, in order to give the mixed raw materials the above-mentioned structure, raw materials Al, Ni, Co, Cr, Mo and Nb can be laid in sequence from bottom to top during the mixing stage.

[0019] 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 or equal to 100W; the time for the first and second ultrasonic cleanings is preferably 8-12 minutes, more preferably 10-11 minutes. In the present invention, the drying is preferably oven drying; the drying temperature is preferably 50-100°C, more preferably 60-80°C; the drying time is preferably 10-40 minutes, more preferably 20-30 minutes.

[0020] In some embodiments of the present invention, the melting temperature is preferably 1500~2000℃, more preferably 1700~1850℃. The melting is preferably carried out under a protective atmosphere; the protective atmosphere preferably includes argon. The melting is preferably non-consumable vacuum arc melting. The specific method for forming the protective atmosphere is: after evacuating the arc melting furnace, a protective gas is introduced; 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. The current of the non-consumable vacuum arc melting is preferably 45~75A, more preferably 70A.

[0021] 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. Specifically, the oxygen scavenger is preferably placed in a pre-reserved crucible in the smelting equipment, so as to facilitate the adsorption of residual oxygen in the protective atmosphere after the oxygen scavenger melts, thereby reducing oxidation behavior during alloy smelting. 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 the oxygen scavenger, as long as it can remove residual oxygen in the protective atmosphere. The present invention has no special requirements for the smelting equipment, and conventional smelting equipment can be used. The smelting equipment can be a smelting furnace.

[0022] In some embodiments of the present invention, after the raw materials are melted, stirring is preferably performed, and the stirring is preferably electromagnetic stirring; the electromagnetic stirring time is preferably 50-100s, more preferably 60-80s. The raw materials are mixed uniformly under the action of electromagnetic stirring. It is understood that the melting time is the sum of the melting time and the stirring time.

[0023] In some embodiments of the present invention, the solidification is preferably carried out in a water-cooled copper crucible. The present invention does not have special requirements for the solidification process; conventional methods in the art can be used.

[0024] After obtaining the alloy material with a primary nanostructure, the present invention repeatedly melts and solidifies it to obtain the high-entropy alloy material with the antioxidant nanostructure. Specifically, 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. The number of repetitions is preferably 3 to 6 times, more preferably 4 to 5 times.

[0025] Compared with the prior art, the technical solution provided by the present invention has at least the following advantages: This invention provides a high-entropy alloy material with an antioxidant nanostructure, its preparation method, and its application. The high-entropy alloy material with the antioxidant nanostructure is a NiCoCrAlMoNb alloy with a nanostructure. The formulation of this NiCoCrAlMoNb alloy incorporates a high content of Mo and Nb, which are uniformly dispersed in the alloy. During oxidation, a protective Mo and Nb-modified Al2O3 film is formed. The precipitated phase ensures corrosion resistance, and precipitation strengthening improves high-temperature mechanical properties, inhibits high-temperature interface deformation of the oxide film, and further enhances antioxidant performance. Furthermore, the nanostructure of this NiCoCrAlMoNb alloy increases the Al diffusion rate, further ensuring the high-temperature oxidation resistance of the nanostructure. Using this NiCoCrAlMoNb alloy as a binder layer material results in a binder layer with excellent antioxidant properties. Attached Figure Description

[0026] 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.

[0027] Figure 1 The image is a scanning electron microscope backscattered electron image of the NiCoCrAlMoNb alloy provided in Example 1 of this invention; Figure 2 The cross-sectional morphology of the NiCoCrAlMoNb alloy provided in Example 1 of this invention after oxidation at 1100℃ for 500h; Figure 3 The cross-sectional morphology of the NiCoCrAlMoNb alloy provided in Example 1 of this invention after oxidation at 1200℃ for 500h. Detailed Implementation

[0028] The present invention will now be described in detail with reference to specific embodiments.

[0029] Example 1 Nickel, cobalt, chromium, aluminum, molybdenum, and niobium metal particles with a purity of 99.9% and an average particle size of 4 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.

[0030] Al: 9.3 g (accounting for 20 at.% of the atomic percentage of the NiCoCrAlMoNb alloy); Ni: 20.2 g (accounting for 20 at.% of the atomic percentage of the NiCoCrAlMoNb alloy); Co: 20.2g (accounting for 20 at.% of the atomic percentage of the NiCoCrAlMoNb alloy); Cr: 17.9 g (20 at.% of the atomic percentage of the NiCoCrAlMoNb alloy); Mo: 16.5 g (accounting for 10 at.% of the atomic percentage of the NiCoCrAlMoNb alloy); Nb: 20.0 g (accounting for 10 at.% of the atomic percentage of the NiCoCrAlMoNb alloy).

[0031] Al, Ni, Co, Cr, Mo, and Nb 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; arc melting of titanium sheet for 3 min to adsorb residual oxygen in 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 maintained for 60 s. The melt is then solidified in a water-cooled copper crucible and the ingot is flipped using a robot. The melting and solidification are repeated 5 times to obtain 100 g NiCoCrAlMoNb alloy button ingot.

[0032] The resistance to molten salt hot corrosion of the NiCoCrAlMoNb alloy prepared in Example 1 was tested according to the following steps: (1) In Example 1, the NiCoCrAlMoNb alloy has a nanostructure, with a NiCoMo-rich phase as the matrix and CrAlNb-rich and MoNb-rich phases as precipitates, 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) The NiCoCrAlMoNb sample from (1) was placed directly in a muffle furnace and tested for high-temperature oxidation resistance at 1100℃ in an atmospheric environment. Figure 2 This is a cross-sectional image of the NiCoCrAlMoNb sample after 500 hours of oxidation. A uniform and continuous oxide film grows on the surface, and the oxide film does not peel off from the interface, indicating that the alloy has excellent oxidation resistance at 1100℃.

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

[0034] Example 2 Nickel, cobalt, chromium, aluminum, molybdenum, and niobium metal 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. After drying at 60℃ for 10 min, they were ready for use.

[0035] Al: 8.4 g (accounting for 18 at.% of the atomic percentage of the NiCoCrAlMoNb alloy); Ni: 30.6 g (30 at.% of the atomic percentage of NiCoCrAlMoNb alloy); Co: 18.4 g (accounting for 18 at.% of the atomic percentage of the NiCoCrAlMoNb alloy); Cr: 16.3 g (accounting for 18 at.% of the atomic percentage of the NiCoCrAlMoNb alloy); Mo: 13.4 g (8 at.% of the atomic percentage of the NiCoCrAlMoNb alloy); Nb: 12.9 g (8 at.% of the atomic percentage of the NiCoCrAlMoNb alloy).

[0036] Al, Ni, Co, Cr, Mo, and Nb are layered in the electric arc melting furnace in the order from bottom to top; after placing the titanium sheet in the pre-reserved crucible in the melting furnace, the vacuum electric arc melting furnace is evacuated to 4 × 10⁻⁶. -3 Pa, argon gas is introduced to 5 Pa; arc melting of titanium sheet for 3 min to adsorb residual oxygen in protective atmosphere; under argon protection, non-consumable vacuum arc melting is carried out for 1 min at a current of 75 A and a temperature of 1800 °C. After the raw material is fully melted, electromagnetic stirring is turned on and maintained for 60 s. The melt is then solidified in a water-cooled copper crucible and the ingot is flipped using a robot. The melting and solidification are repeated 5 times to obtain 100 g NiCoCrAlMoNb alloy button ingot.

[0037] Example 3 Nickel, cobalt, chromium, aluminum, molybdenum, and niobium metal particles with a purity of 99.9% and an average particle size of 5 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. After drying at 60℃ for 10 min, they were ready for use.

[0038] Al: 10.6 g (accounting for 23 at.% of the atomic percentage of the NiCoCrAlMoNb alloy); Ni: 7.0 g (accounting for 7 at.% of the atomic percentage of the NiCoCrAlMoNb alloy); Co: 32.2 g (accounting for 23 at.% of the atomic percentage of the NiCoCrAlMoNb alloy); Cr: 20.5 g (accounting for 23 at.% of the atomic percentage of the NiCoCrAlMoNb alloy); Mo: 19.7 g (accounting for 12 at.% of the atomic percentage of the NiCoCrAlMoNb alloy); Nb: 19.1 g (accounting for 12 at.% of the atomic percentage of the NiCoCrAlMoNb alloy).

[0039] Al, Ni, Co, Cr, Mo, and Nb are layered in the electric arc melting furnace in the order from bottom to top; after placing the titanium sheet in the pre-reserved crucible in the melting furnace, the vacuum electric arc melting furnace is evacuated to 5 × 10⁻⁶. -3 Pa, argon gas is introduced to 5 Pa; arc melting of titanium sheet for 3 min to adsorb residual oxygen in protective atmosphere; under argon protection, non-consumable vacuum arc melting is carried out for 1 min at a current of 45 A and a temperature of 1700 °C. After the raw material is fully melted, electromagnetic stirring is turned on and maintained for 60 s. The melt is then solidified in a water-cooled copper crucible and the ingot is flipped using a robot. The melting and solidification are repeated 5 times to obtain 100g NiCoCrAlMoNb alloy button ingot.

[0040] 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 high-entropy alloy material with an antioxidant nanostructure, characterized in that, The high-entropy alloy material with the antioxidant nanostructure is a NiCoCrAlMoNb alloy, which comprises the following elements by atomic percentage: Co18~23 at.%% Cr 18~23 at.%; Al18~23 at.%% Mo8~12 at.%% Nb8~12 at.%% Ni balance.

2. The high-entropy alloy material with an antioxidant nanostructure according to claim 1, characterized in that, The NiCoCrAlMoNb alloy has a nanostructure, which includes a NiCoMo-rich phase as the matrix and a CrAlNb-rich phase as the precipitated phase.

3. The high-entropy alloy material with an antioxidant nanostructure according to claim 2, characterized in that, The nanostructure also includes a MoNb-rich phase as the precipitated phase.

4. The high-entropy alloy material with an antioxidant nanostructure according to claim 1, characterized in that, After the NiCoCrAlMoNb alloy is subjected to oxidation treatment at 1200℃ or below for no more than 500 hours, the oxide film formed on the surface does not peel off.

5. A method for preparing a high-entropy alloy material with an antioxidant nanostructure according to any one of claims 1 to 4, characterized in that, The preparation method includes: After converting the atomic ratio of the NiCoCrAlMoNb 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 an alloy material with a primary nanostructure. The alloy material with the primary nanostructure is repeatedly melted and solidified to obtain the high-entropy alloy material with the antioxidant nanostructure.

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

7. The method for preparing the high-entropy alloy material with antioxidant nanostructure according to claim 5, characterized in that, The melting was carried out under a protective atmosphere; The melting temperature is 1500~2000℃.

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

10. The application of a high-entropy alloy material with an antioxidant nanostructure according to any one of claims 1 to 4 as a binder material.

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