Eutectic high-entropy alloy, preparation method thereof and casting target material

Abstract

The embodiment of the invention provides a eutectic high-entropy alloy, a preparation method thereof and a casting target material. The eutectic high-entropy alloy comprises the following components in atomic percent: 14 to 19.5 at% of Al, 16 to 19 at% of Co, 16 to 19 at% of Cr, 13 to 17 at% of Fe, 0.01 to 0.1 at% of Y, 0.01 to 0.1 at% of Hf and the balance of Ni. Therefore, the eutectic high-entropy alloy has excellent oxidation resistance at a high temperature, a generated oxidation film is uniform and compact, the bonding state is good, the toughness is also considered, the eutectic high-entropy alloy is particularly suitable for preparing a casting target material for a high-oxidation-resistance coating through vacuum arc ion plating, and the oxidation resistance requirement of a superhigh-temperature metal bonding layer coating can be met.

Description

Technical Field

[0001] This disclosure relates to the field of thermal barrier coating preparation technology, and in particular to a eutectic high entropy alloy and its preparation method, and a casting target. Background Technology

[0002] Thermal barrier coating (TBC) technology is widely used for high-temperature protection of turbine blades in gas turbines and aero-engines. For example, to reduce the surface temperature of hot-end components in aero-engines and improve their resistance to oxidation and corrosion, surface thermal protection technology using TBCs is commonly employed. TBCs typically consist of a ceramic layer that provides insulation and a bonding layer that mitigates the thermal expansion mismatch between the ceramic layer and the substrate alloy, thereby improving the substrate's resistance to oxidation and corrosion. With the continuous improvement of aero-engine thrust and operating efficiency, the gas inlet temperature is increasing. Even excluding the insulation effect of the ceramic layer in the TBC and the film cooling effect of the blades themselves, the surface operating temperature of the bonding layer will reach 1150℃ or 1200℃. Currently, MCrAlY and Ni-Al based high-temperature protective metal bonding layers are commonly used. Their main function is to generate a dense Al2O3 oxide film in high-temperature environments, providing good oxidation protection for the substrate. However, the long-term service temperature of the widely used MCrAlY bonding layer generally does not exceed 1100℃. At higher service temperatures, the oxidation rate increases dramatically, forming non-protective oxides such as spinel, leading to rapid coating failure. Although Ni-Al based adhesive layers can rapidly form a continuous and dense protective α-Al2O3 film during service at 1150℃ or 1200℃, thus preventing further diffusion of external oxygen into the substrate and improving ultra-high temperature oxidation resistance, the high content of the brittle β-NiAl phase easily leads to poor adhesion between the oxide film and the coating. As the oxidation time increases, the continuous thickening of the oxide film leads to the continuous accumulation of internal stress, which easily causes cracking and peeling, limiting the long service life of the coating.

[0003] Since its introduction in 2004, high-entropy alloys (HEAs) have demonstrated superior properties unmatched by traditional alloys simultaneously, due to four major effects: the high-entropy effect, the structural lattice distortion effect, the kinetic hysteresis diffusion effect, and the performance-enhancing cocktail effect. These properties include high fracture toughness, high strength, high hardness, high wear resistance, high oxidation resistance, high corrosion resistance, and radiation resistance. The high mixing entropy gives HEAs a simple solid solution structure, such as face-centered cubic (FCC), body-centered cubic (BBC), or FCC+BCC. The kinetic hysteresis diffusion effect slows down the diffusion rate of alloying elements, thus reducing the alloy's oxidation rate. Therefore, HEAs hold promise as high-temperature protective coating materials and represent a promising high-temperature protective coating system.

[0004] However, current eutectic high-entropy alloys, their preparation methods, and casting targets still need improvement. Summary of the Invention

[0005] This disclosure provides a eutectic high-entropy alloy and its preparation method, as well as a casting target, to solve or alleviate one or more technical problems in the related art.

[0006] As a first aspect of the present disclosure, the present disclosure provides a eutectic high-entropy alloy, which, by atomic percentage, comprises: Al 14-19.5 at%, Co 16-19 at%, Cr 16-19 at%, Fe 13-17 at%, Y 0.01-0.1 at%, Hf 0.01-0.1 at%, with the remainder being Ni.

[0007] In one possible implementation, the eutectic high-entropy alloy comprises, by atomic percentage: Al 14-16.4 at%, Co 16-17.5 at%, Cr 16-17.5 at%, Fe 15.5-17 at%, Y 0.01-0.03 at%, Hf 0.01-0.03 at%, with the remainder being Ni.

[0008] In one possible implementation, the phase composition of the eutectic high-entropy alloy includes 42-46% ordered B2 phase, 53-57% FCC phase, and 0.2-1.5% Y- and Hf-rich phases; in the microstructure of the eutectic high-entropy alloy, the B2 phase and the FCC phase are partially distributed in alternating lamellar or rod-like forms, and the Y- and Hf-rich phases are located at the interface between the B2 phase and the FCC phase.

[0009] In one possible implementation, the eutectic high-entropy alloy is isothermally oxidized at 1150°C and 1200°C for 200 h to form a uniform and dense α-Al2O3 oxide layer.

[0010] In one possible implementation, the oxidation rate of the eutectic high-entropy alloy after isothermal oxidation at 1150°C for 100 hours is 0.034-0.049 g / (m³). 2 The oxidation rate of the eutectic high-entropy alloy after isothermal oxidation at 1150℃ for 200 h is 0.027-0.034 g / (m). 2 The oxidation rate of the eutectic high-entropy alloy after isothermal oxidation at 1200℃ for 100 h is 0.040-0.054 g / (m). 2 The oxidation rate of the eutectic high-entropy alloy after isothermal oxidation at 1200℃ for 200 h is 0.028-0.038 g / (m). 2 ·h).

[0011] In one possible implementation, the oxidation rate of the eutectic high-entropy alloy after isothermal oxidation at 1150°C for 100 hours is 0.034-0.042 g / (m³).2 The oxidation rate of the eutectic high-entropy alloy after isothermal oxidation at 1150℃ for 200 h is 0.027-0.030 g / (m). 2 The oxidation rate of the eutectic high-entropy alloy after isothermal oxidation at 1200℃ for 100 h is 0.040-0.046 g / (m). 2 The oxidation rate of the eutectic high-entropy alloy after isothermal oxidation at 1200℃ for 200 h is 0.028-0.035 g / (m). 2 ·h).

[0012] In one possible implementation, the eutectic high-entropy alloy has a processing Rockwell hardness of 31-35.5 HRC.

[0013] As a second aspect of this disclosure, this disclosure provides a method for preparing the eutectic high-entropy alloy described in any of the preceding claims. The method includes vacuum induction melting and vacuum casting. The method further includes: grinding and cleaning the metal raw material to obtain a clean raw material, the clean raw material including pure metals of Ni, Co, Cr, Fe, Al, Hf, and Y; and loading the pure metals of Ni, Co, Cr, and Fe into a crucible according to a specified ratio for vacuum induction melting, wherein the vacuum degree during the melting process is 10... -3 -10 -2 Heat the clean raw material at 5-15 kW for 10-15 minutes, then adjust the power to 30-40 kW and maintain for 10-20 minutes. Finally, adjust the power to 45-50 kW and melt the clean raw material at 1550-1600°C. After the clean raw material is melted, reduce the power to 10-15 kW and wait for 5-10 minutes. Then, purge with high-purity argon gas to 2000-3000 Pa and add Al particles. Stir for 2 minutes, then add metallic Y and Hf. Then, increase the power to 40-45 kW, stir and heat, and melt at 1500-1600°C. Refining at 0℃ for 5-10 minutes forms an alloy liquid; after refining, the power is reduced to 10-20Kw, and vacuum casting is performed when the temperature of the alloy liquid drops to 1450-1500℃; precision casting is performed using a ceramic mold shell, the mold shell baking temperature is 800-1100℃, the vacuum degree of the vacuum casting process is 0.1-5Pa, the casting time of the vacuum casting process is 3-5s, after casting, wait 1-10 minutes to break the vacuum and air cool to room temperature in an atmospheric environment, break the shell to obtain a eutectic high-entropy alloy ingot, and obtain the eutectic high-entropy alloy.

[0014] In one possible implementation, the clean raw materials include 99.95wt% pure Ni blocks, 99.95wt% pure Co blocks, 99.9wt% pure Cr particles, 99.99wt% pure electrolytic iron, 99.99wt% pure Al particles, 99.95wt% pure Hf particles, and 99.9wt% pure Y button ingots after calcium removal. After loading the clean raw materials into the crucible according to the specified ratio, the method further includes: closing the furnace door, turning on the mechanical pump to evacuate to below 500 Pa, and then turning on the Roots pump to evacuate to below 10 Pa. -1 Pa-10 -2 Pa, finally turn on the oil diffusion pump to evacuate to 10 Pa. -2 Pa-10 -3 Pa; The precision casting is performed using a cylindrical ceramic mold shell, and the shell is broken to obtain a cylindrical eutectic high-entropy alloy ingot.

[0015] As a third aspect of the present disclosure, the present disclosure provides a casting target material comprising any of the preceding claims of a eutectic high-entropy alloy, or comprising a eutectic high-entropy alloy prepared by the preceding methods, wherein the casting target material can be used to prepare the adhesive layer of a thermal barrier coating by a vacuum arc ion plating process. Attached Figure Description

[0016] In the accompanying drawings, unless otherwise specified, the same reference numerals throughout the various drawings denote the same or similar parts or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings depict only some embodiments according to this disclosure and should not be construed as limiting the scope of this disclosure.

[0017] Figure 1 This is a schematic diagram of a method for preparing a eutectic high-entropy alloy according to an embodiment of the present disclosure; Figure 2 Scanning electron microscope (SEM) images of the phase composition of a eutectic high-entropy alloy according to embodiments of this disclosure; Figure 3 Scanning electron microscope (SEM) images of the phase composition of a high-entropy alloy according to the comparative examples of this disclosure; Figure 4 XRD pattern of phase composition of eutectic high-entropy alloy according to embodiments of the present disclosure; Figure 5 XRD patterns of phase composition of high-entropy alloys according to comparative examples of this disclosure; Figure 6 This is a comparison chart showing the weight gain of high-entropy alloys from embodiments and comparative examples of this disclosure after isothermal oxidation at 1150°C for 200 hours. Figure 7 This is a comparison chart showing the weight gain of high-entropy alloys from embodiments and comparative examples of this disclosure after isothermal oxidation at 1200°C for 200 hours. Figure 8 The image shows the XRD pattern of the eutectic high-entropy alloy according to the embodiments of this disclosure after isothermal oxidation at 1150°C for 200 h. Figure 9 The image shows the XRD pattern of the eutectic high-entropy alloy according to an embodiment of the present disclosure after isothermal oxidation at 1200°C for 200 h. Figure 10 The image shows the surface morphology of the eutectic high-entropy alloy after isothermal oxidation at 1200°C for 200 hours according to an embodiment of the present disclosure; Figure 11 The image shows the surface morphology of a high-entropy alloy after isothermal oxidation at 1200°C for 200 h, according to the comparative example of this disclosure, using a scanning electron microscope. Detailed Implementation

[0018] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of this disclosure, and different embodiments can be combined arbitrarily without conflict. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0019] As a first aspect of the present disclosure, this embodiment provides a eutectic high-entropy alloy, which, by atomic percentage, may comprise: Al 14-19.5 at%, Co 16-19 at%, Cr 16-19 at%, Fe 13-17 at%, Y 0.01-0.1 at%, Hf 0.01-0.1 at%, with the remainder being Ni. Therefore, this eutectic high-entropy alloy exhibits excellent oxidation resistance at high temperatures, producing a uniform and dense oxide film with good bonding, while also possessing both strength and toughness. It is particularly suitable for casting targets used in vacuum arc ion plating to prepare high-oxidation-resistant coatings, and can meet the oxidation resistance requirements of ultra-high temperature metal bonding coatings.

[0020] For ease of understanding, the principle by which the eutectic high-entropy alloy according to the embodiments of this application achieves the above-mentioned beneficial effects will be explained in detail below: With the continuous improvement of aero-engine thrust and operating efficiency, the gas intake temperature is getting higher and higher, and the surface operating temperature of the bonding layer will reach 1150℃ or 1200℃. High-entropy alloys, due to their unique properties, are expected to serve as high-temperature protective coating materials and are a promising high-temperature protective coating material system. Currently, high-entropy alloy coatings are usually prepared using processes such as laser cladding, supersonic flame spraying, and plasma spraying. For example, some methods use vacuum suspension melting + planetary ball mill crushing and powdering + atmospheric plasma spraying to prepare an antioxidant high-entropy bonding layer coating with an equal atomic ratio of Al, Co, Cr, Fe, and Ni. Compared with the traditional NiCoCrAlY bonding layer, the high-entropy bonding layer coating did not show any form of peeling after 200 thermal cycles of oxidation at 1150℃ and 1200℃, and its oxidation resistance was superior. However, its oxidation rate was not published. Some methods employ vacuum arc melting + vacuum argon atomization powder preparation + supersonic plasma spraying to prepare high-entropy alloy coatings resistant to oxidation at 1200℃. After isothermal oxidation at 1200℃ for 500 hours, a single Al2O3 oxide film forms on the surface. In reality, these techniques are mainly used to prepare high-entropy alloy coatings due to their simple operation or the difficulty in preparing target materials due to the high brittleness of the developed high-entropy alloys.

[0021] However, in the field of binder coating preparation, especially for high-pressure turbine blades of engines, physical vapor deposition techniques such as magnetron sputtering, electron beam physical vapor deposition, and vacuum arc ion plating are highly regarded due to their good coating density, small pores, and good metallurgical bonding. Among these, vacuum arc ion plating is the most widely used for preparing metal binder layers. One method involves using AlCoCrFeNi high-entropy alloy targets and magnetron sputtering to prepare Dy and Hf modified AlCoCrFeNi high-entropy films to improve the oxidation resistance of TiAl alloys. However, this method is limited to an oxidation temperature of 900℃, which is not very relevant for ultra-high temperature oxidation. Furthermore, the deposition rate of magnetron sputtering is relatively slow, resulting in low production efficiency. Another method involves using electron beam physical vapor deposition to evaporate and deposit a double-layer microstructured FeCoNiCrAl high-entropy coating on DD6 single-crystal high-temperature alloy samples. A static oxidation test at 1200℃ for 100 hours was conducted and compared with that of a Ni-Al coating. The results showed that neither achieved complete oxidation resistance.

[0022] In summary, current high-entropy alloys, when used as high-temperature protective coating materials, especially as adhesive coating materials, such as the adhesive coating for high-pressure turbine blades in engines, suffer from incompatibility with existing adhesive coating preparation processes (e.g., vacuum arc ion plating) and poor oxidation resistance at high temperatures (e.g., 1150℃, 1200℃). In this application, the inventors, through in-depth and extensive research, discovered that optimizing the composition of high-entropy alloys can significantly improve their oxidation resistance and ensure compatibility with subsequent coating preparation processes. Therefore, the eutectic high-entropy alloy designed in this application, by controlling the content range of the main components Al, Co, Cr, Fe, and Ni, guarantees a configuration entropy higher than 1.5R, conforming to the basic characteristics of high-entropy alloys. Furthermore, this eutectic high-entropy alloy exhibits certain eutectic characteristics, a short solidification temperature range, and good liquid fluidity, facilitating mold filling and reducing casting defects. This eutectic high-entropy alloy possesses excellent strength-toughness matching, effectively solving the cracking problem of cast high-entropy alloy targets and ensuring that the prepared coating does not fail prematurely due to stress concentration caused by excessive brittleness. Simultaneously, the addition of appropriate amounts of active elements Y and Hf improves the interfacial bonding performance of the oxide layer and enhances the alloy's oxidation resistance. The eutectic high-entropy alloy in this application exhibits excellent oxidation resistance after oxidation at 1150℃ and 1200℃ for 100h and 200h, respectively, with oxidation rates reaching the fully oxidation-resistant level; the oxide layer is uniform, and the phase is a single, stable α-Al₂O₃. The eutectic high-entropy alloy material in this application has the potential to be used as a target material for preparing high-temperature protective coatings in vacuum arc plating processes.

[0023] According to some embodiments of this application, the Al content in the eutectic high-entropy alloy, by atomic percentage, can be 15 at%, 16 at%, 17 at%, 18 at%, 19 at%, 14-16.4 at%, etc.; the Co content in the eutectic high-entropy alloy can be 17 at%, 18 at%, 16-17.5 at%, etc.; the Cr content in the eutectic high-entropy alloy can be 17 at%, 18 at%, 16-17.5 at%, etc.; the Fe content in the eutectic high-entropy alloy can be 14 at%, 15 at%, 16 at%, 15.5-17 at%, etc.; the Y content in the eutectic high-entropy alloy can be 0.02 at%, 0.04 at%, 0.05 at%, 0.06 at%, 0.07 at%, 0.08 at%, 0.09 at%, 0.01-0.03 at%, etc.; the Hf content in the eutectic high-entropy alloy can be 0.02 at%, 0.04 at%, 0.05 at%, 0.06 at%, etc. The components in this eutectic high-entropy alloy, when their contents are within the above ranges, exhibit good oxidation resistance at high temperatures, good bonding, and good strength and toughness.

[0024] According to some embodiments of this application, the phase composition of the eutectic high-entropy alloy may include 42-46% ordered B2 phase, 53-57% FCC phase, and 0.2-1.5% Y- and Hf-rich phases. Specifically, the phase composition of the eutectic high-entropy alloy may include 43%, 44%, or 45% ordered B2 phase, 54%, 55%, or 56% FCC phase, and 0.4%, 0.5%, 0.8%, 1%, 1.2%, or 1.4% Y- and Hf-rich phases. In one possible embodiment, in the microstructure of the eutectic high-entropy alloy, the B2 phase and FCC phase may be distributed in an alternating lamellar or rod-like manner, and the Y- and Hf-rich phase may be located at the interface between the B2 phase and the FCC phase. Therefore, the microstructure of this high-entropy alloy consists of a face-centered cubic (FCC) structure rich in Cr and Fe with insufficient oxidation resistance but good toughness, and a body-centered cubic (BCC_B2) structure rich in Al with good oxidation resistance but high brittleness, which fully takes into account the dual requirements of the target material preparation for the mechanical properties of the high-entropy alloy and the high oxidation resistance of the target material itself.

[0025] According to some embodiments of this application, a uniform and dense α-Al2O3 oxide layer can be formed by isothermal oxidation of eutectic high-entropy alloys at 1150°C and 1200°C for 200 h.

[0026] According to some embodiments of this application, the oxidation rate of a eutectic high-entropy alloy is 0.034-0.049 g / (m³) during isothermal oxidation at 1150°C for 100 h. 2 •h), for example, can be 0.034-0.042 g / (m 2 ·h), can be 0.043 g / (m 2 ·h), 0.044 g / (m 2 ·h), 0.045 g / (m 2 ·h), 0.046 g / (m 2 ·h), 0.047 g / (m 2 ·h), 0.048 g / (m 2 The oxidation rate of this eutectic high-entropy alloy under isothermal oxidation at 1150℃ for 200 h can be 0.027-0.034 g / (m). 2 (·h), for example, can be 0.027-0.030 g / (m 2 · h), can be 0.028 g / (m 2 ·h), 0.029 g / (m 2 ·h), 0.031 g / (m 2 ·h), 0.032 g / (m 2 ·h), 0.033 g / (m 2The oxidation rate of this eutectic high-entropy alloy under isothermal oxidation at 1200℃ for 100 h can be 0.040-0.054 g / (m). 2 •h), for example, can be 0.040-0.046 g / (m 2 ·h), can be 0.042 g / (m 2 ·h), 0.044 g / (m 2 ·h), 0.048g / (m 2 ·h), 0.050 g / (m 2 ·h), 0.052 g / (m 2 ·h), 0.053g / (m 2 The oxidation rate of this eutectic high-entropy alloy under isothermal oxidation at 1200℃ for 200 h can be 0.028-0.038 g / (m). 2 (·h), for example, can be 0.028-0.035 g / (m 2 · h), can be 0.029 g / (m 2 ·h), 0.030 g / (m 2 ·h), 0.032 g / (m 2 ·h), 0.034 g / (m 2 ·h), 0.037 g / (m 2 Therefore, the eutectic high-entropy alloy of this application can achieve a fully oxidation-resistant grade when isothermally oxidized at 1150℃ and 1200℃.

[0027] According to some embodiments of this application, the processing Rockwell hardness of the eutectic high-entropy alloy can be 31-35.5 HRC, for example, 32 HRC, 33 HRC, 34 HRC, 35 HRC, etc. Therefore, the eutectic high-entropy alloy possesses both good strength and toughness.

[0028] As a second aspect of the present disclosure, the present disclosure provides a method for preparing the eutectic high-entropy alloy described in any of the preceding claims. The eutectic high-entropy alloy prepared by this method has all the characteristics and advantages of the eutectic high-entropy alloy described in the preceding claims, which will not be repeated here.

[0029] According to some embodiments of this application, the method includes vacuum induction melting and vacuum casting, see reference. Figure 1 The method further includes: S100: Grinding and cleaning the metal raw materials to obtain clean raw materials. In this step, the metal raw materials are polished and cleaned to obtain clean raw materials. The clean raw materials may include pure metals such as Ni, Co, Cr, Fe, Al, Hf, and Y. Specifically, the clean raw materials may include 99.95wt% pure Ni blocks, 99.95wt% pure Co blocks, 99.9wt% pure Cr particles, 99.99wt% pure electrolytic iron, 99.99wt% pure Al particles, 99.95wt% pure Hf particles, and 99.9wt% pure Y button ingots after calcium removal.

[0030] S200: Clean raw materials are subjected to vacuum induction melting to form an alloy liquid. In this step, pure metals Ni, Co, Cr, and Fe are first loaded into a crucible according to the specified ratio and then subjected to vacuum induction melting. The vacuum degree during the melting process can be 10. -3 -10 -2 Specifically, the furnace door can be closed, the mechanical pump can be turned on to evacuate to below 500 Pa, and then the Roots pump can be turned on to evacuate to below 10 Pa. -1 Pa-10 -2 Pa, finally turn on the oil diffusion pump to evacuate to 10 Pa. -2 Pa-10 -3 Pa. Next, heat with a power of 5-15 kW for 10-15 minutes, then adjust the power to 30-40 kW and maintain for 10-20 minutes. Finally, adjust the power to 45-50 kW and melt the clean raw material at 1550-1600℃. After the clean raw material is completely melted, reduce the power to 10-15 kW and wait 5-10 minutes. Then, purge with high-purity argon gas to 2000-3000 Pa, add Al particles, stir for 2 minutes, then add metallic Y and Hf. Increase the power to 40-45 kW, stir and heat, and refine at 1500-1600℃ for 5-10 minutes to form an alloy liquid. Specifically, the initial melting power can be 8-12 kW, and the vacuum degree during melting can be 5 × 10⁻⁶. -3 -1×10 -2 Pa, the temperature for melting the clean raw material can be 1500-1550℃, and the melting time for the clean raw material can be 5-8 minutes.

[0031] S300: Vacuum casting is performed on the molten alloy to obtain a eutectic high-entropy alloy ingot. In this step, after the refining process described above is completed, the power can be reduced to 10-20 kW, and vacuum casting can be performed when the alloy liquid temperature drops to 1450-1500℃. Precision casting can be performed using a ceramic mold, with a mold baking temperature of 800-1100℃, a vacuum degree of 0.1-5 Pa, and a casting time of 3-5 seconds. After casting, wait 1-10 minutes for air cooling to room temperature in an atmospheric environment to obtain a eutectic high-entropy alloy ingot. Specifically, vacuum casting can be performed when the alloy liquid temperature drops to 1480-1490℃, with a mold baking temperature of 750-850℃, a casting vacuum degree controlled at 0.5-2 Pa, a casting time of 3-4 seconds, and a waiting time of 1-2 minutes. Alternatively, a cylindrical ceramic mold can be used for precision casting, and the ingot can be obtained by breaking the mold.

[0032] As a third aspect of this disclosure, an embodiment provides a casting target comprising the eutectic high-entropy alloy described in any of the preceding claims, or comprising the eutectic high-entropy alloy prepared by the methods described above. This casting target can be used in vacuum arc ion plating to prepare the bonding layer of a thermal barrier coating. Therefore, this casting target possesses all the characteristics and advantages of the aforementioned eutectic high-entropy alloy, which will not be elaborated further here. In general, this casting target exhibits excellent oxidation resistance at high temperatures, produces a uniform and dense oxide film with good bonding, and also maintains high strength and toughness. It is particularly suitable as a casting target for preparing high-oxidation-resistant coatings by vacuum arc ion plating, and can meet the oxidation resistance requirements of ultra-high temperature metal bonding layer coatings.

[0033] Example 1 The eutectic high-entropy alloy, by atomic percentage, consists of Al 15.7 at%, Co 16.2 at%, Cr 17.1 at%, Fe 15.8 at%, Y 0.012 at%, Hf 0.018 at%, with the remainder being Ni.

[0034] The preparation process of eutectic high-entropy alloy is as follows: melting is performed using a medium-frequency vacuum induction furnace. The raw materials are cleaned and dried before being fed into the furnace. Pure metals, including Ni blocks, Co blocks, Cr granules, and Fe granules, are loaded into a zirconium oxide crucible according to the specified proportions, and the furnace is evacuated to 10°C. -3After Pa, the furnace charge was initially heated at 12 kW for 15 minutes, then adjusted to 36 kW and maintained for 15 minutes. Finally, the charge was melted at 1580℃ with 45 kW. After the charge was completely melted, the power was reduced to 15 kW and waited for 5 minutes. The vacuum pump was then turned off, and high-purity argon gas was introduced to 2000 Pa. Al particles were added, and the mixture was stirred for 2 minutes. Metallic Y and Hf were then added, and the power was increased to 40 kW while stirring and heating. The mixture was then refined at 1550℃ for 5 minutes. After refining, the power was reduced to 10 kW, and vacuum casting was performed when the alloy liquid temperature dropped to 1480℃. The mold shell baking temperature was 800℃, the casting vacuum degree was controlled at 2 Pa, and the casting time was controlled at 3 seconds. After casting, the mixture was allowed to cool to room temperature in an atmospheric environment after 1 minute. The resulting cylindrical eutectic high-entropy alloy ingot with a diameter of 80 mm was obtained.

[0035] Comparative Example 1 The high-Al high-entropy alloy has the following atomic percentage composition: Al 25.6 at%, Co 14.2 at%, Cr 14.5 at%, Fe 15.1 at%, Y 0.012 at%, Hf 0.018 at%, with the remainder being Ni. The atomic percentages of Y and Hf are the same as in Example 1, and the process parameters for smelting the high-entropy alloy are also the same as in Example 1.

[0036] Performance testing (1) SEM test The high-entropy alloy phase composition of Example 1 and Comparative Example 1 was analyzed by SEM morphology testing, and the obtained SEM morphology images are referenced. Figure 2 and Figure 3 .

[0037] Figure 2 The image shows the SEM morphology of the eutectic high-entropy alloy phase composition provided in Example 1. It can be seen that the dark gray B2 phase is rod-shaped and regularly arranged with the light gray FCC phase, exhibiting partial eutectic characteristics. The B2 phase content is 43.0%, the FCC phase content is 56.8%, and the Y- and Hf-rich phase content is 0.2%.

[0038] Figure 3 The SEM image shows the phase composition of the high-entropy alloy with high Al content provided for Comparative Example 1. The phase composition consists of obvious blocky B2 phase and FCC phase, with B2 phase accounting for 68.5%, FCC phase accounting for 31.4%, and Y- and Hf-rich phase accounting for 0.1%.

[0039] (2) XRD test XRD analysis was performed on the high-entropy alloy phase composition of Example 1 and Comparative Example 1. The obtained XRD patterns are referenced. Figure 4 and Figure 5(The horizontal axis represents 2θ angle / °, and the vertical axis represents intensity; the coordinates for other XRD plots are the same.) Figure 4 as well as Figure 5 ).

[0040] Depend on Figure 4 Example 1 and Figure 5 XRD analysis of the phase composition of both in Comparative Example 1 shows that the FCC phase of the eutectic high-entropy alloy in Example 1 has the strongest diffraction peak, while the B2 phase of the high-entropy alloy in Comparative Example 1 has the strongest diffraction peak.

[0041] Therefore, SEM morphology observation and XRD analysis together indicate that the B2 phase content in Comparative Example 1 is higher than that in Example 1.

[0042] (3) Isothermal oxidation performance test For the high-entropy alloy materials in Example 1 and Comparative Example 1, rectangular test pieces with dimensions of 10mm × 20mm × 1.5mm were cut using an electrical discharge wire cutting machine and polished to 2000# using sandpaper of different grits. According to the standard HB5258-2000 "Test Method for Determination of Oxidation Resistance of Steel and High-Temperature Alloys", high-temperature oxidation experiments were conducted in air at 1150℃ and 1200℃ using a muffle furnace. Every 25 hours, the crucible and test piece were removed and allowed to cool for 3 hours before being weighed using an electronic balance with an accuracy of 0.01mg. This weighing was repeated 10 times, and the mass increase due to oxidation was taken as the average of the mass increases of the four groups of samples.

[0043] Figure 6 and Figure 7 The oxidation weight gain curves of the two high-entropy alloys in Example 1 and Comparative Example 1 after oxidation at 1150℃ and 1200℃ for 200h are shown respectively. It can be seen that although both high-entropy alloys are at the fully oxidation-resistant level at both oxidation temperatures, the oxidation weight gain of the eutectic high-entropy alloy provided in Example 1 is lower than that in Comparative Example 1.

[0044] Meanwhile, the average oxidation rate of the eutectic high-entropy alloy prepared in Example 1 after oxidation at 1150℃ for 100h and 200h was 0.043 g / (m³). 2 ·h), 0.029 g / (m 2 The average oxidation rate of the high-entropy alloy prepared in Comparative Example 1 after oxidation at 1150℃ for 100 h and 200 h was 0.047 g / (m). 2 ·h), 0.034 g / (m 2 The average oxidation rate of the eutectic high-entropy alloy prepared in Example 1 after oxidation at 1200℃ for 100 h and 200 h was 0.044 g / (m). 2 ·h), 0.028 g / (m 2The average oxidation rate of the high-entropy alloy prepared in Comparative Example 1 after oxidation at 1200℃ for 100 h and 200 h was 0.057 g / (m). 2 ·h), 0.033 g / (m 2 ·h).

[0045] Figure 8 and Figure 9 The XRD patterns of the oxide layers of the eutectic high-entropy alloy provided in Example 1 after oxidation at 1150℃ and 1200℃ for 200 h are shown respectively. It can be seen that the oxide layers of the eutectic high-entropy alloy at both temperatures are composed of α-Al2O3 phase, with a small amount of HfO2 oxide phase present.

[0046] Figure 10 and Figure 11 The images show the SEM morphology of the oxide layers of the two high-entropy alloys from Example 1 and Comparative Example 1, respectively, after oxidation at 1200℃ for 200 hours. It can be seen that the eutectic high-entropy alloy oxide layer provided in Example 1 is uniform and dense after oxidation at 1200℃ for 200 hours, while the high-entropy alloy oxide layer in Comparative Example 1, although relatively dense, exhibits some peeling.

[0047] In summary, while appropriately increasing the Al content is beneficial for increasing the amount of Al-rich B2 phase, and the B2-rich phase is an antioxidant phase, thus its antioxidant properties are generally higher, compared with the comparative example, the oxidation rate of the eutectic high-entropy alloy in the examples of this application is lower than that of the high-Al high-entropy alloy in the comparative example when oxidized at 1150℃ or 1200℃ for 200h. This indicates that the partial eutectic morphology improves the antioxidant capacity of the high-entropy alloy. Meanwhile, the eutectic high-entropy alloy prepared in Example 1 has a Rockwell hardness of 33.8 HRC, exhibiting excellent strength-toughness matching, making it suitable for use as a target material in vacuum arc ion plating processes. This ensures that the target material does not become brittle and crack during use, and also avoids the problem of premature coating failure due to excessive brittle phases after coating preparation.

[0048] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this disclosure, "multiple" means two or more, unless otherwise explicitly specified.

[0049] In this disclosure, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0050] In this disclosure, unless otherwise expressly specified and limited, "above" or "below" a second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of a second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" a second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature. The foregoing disclosure provides many different embodiments or examples for implementing different structures of this disclosure. To simplify this disclosure, components and arrangements of specific examples are described above. Of course, these are merely examples and are not intended to limit this disclosure. Furthermore, reference numerals and / or reference letters may be repeated in different examples of this disclosure; such repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed.

[0051] The above are merely specific embodiments of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in this disclosure, and these should all be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A eutectic high-entropy alloy, characterized in that, The eutectic high-entropy alloy comprises, by atomic percentage: Al 14-19.5 at%, Co 16-19 at%, Cr 16-19 at%, Fe 13-17 at%, Y 0.01-0.1 at%, Hf 0.01-0.1 at%, with the remainder being Ni.

2. The eutectic high-entropy alloy according to claim 1, characterized in that, The eutectic high-entropy alloy comprises, by atomic percentage: Al 14-16.4 at%, Co 16-17.5 at%, Cr 16-17.5 at%, Fe 15.5-17 at%, Y 0.01-0.03 at%, Hf 0.01-0.03 at%, with the remainder being Ni.

3. The eutectic high-entropy alloy according to claim 1, characterized in that, The phase composition of the eutectic high-entropy alloy includes 42-46% ordered B2 phase, 53-57% FCC phase, and 0.2-1.5% Y- and Hf-rich phases. In the microstructure of the eutectic high-entropy alloy, the B2 phase and the FCC phase are partially distributed in alternating lamellar or rod-like forms, and the Y- and Hf-rich phases are located at the interface between the B2 phase and the FCC phase.

4. The eutectic high-entropy alloy according to claim 1, characterized in that, The eutectic high-entropy alloy was isothermally oxidized at 1150℃ and 1200℃ for 200h to form a uniform and dense α-Al2O3 oxide layer.

5. The eutectic high-entropy alloy according to claim 4, characterized in that, The oxidation rate of the eutectic high-entropy alloy after isothermal oxidation at 1150℃ for 100 h was 0.034-0.049 g / (m³). 2 The oxidation rate of the eutectic high-entropy alloy after isothermal oxidation at 1150℃ for 200 h is 0.027-0.034 g / (m). 2 The oxidation rate of the eutectic high-entropy alloy after isothermal oxidation at 1200℃ for 100 h is 0.040-0.054 g / (m). 2 The oxidation rate of the eutectic high-entropy alloy after isothermal oxidation at 1200℃ for 200 h is 0.028-0.038 g / (m). 2 ·h).

6. The eutectic high-entropy alloy according to claim 5, characterized in that, The oxidation rate of the eutectic high-entropy alloy after isothermal oxidation at 1150℃ for 100 h was 0.034-0.042 g / (m³). 2 The oxidation rate of the eutectic high-entropy alloy after isothermal oxidation at 1150℃ for 200 h is 0.027-0.030 g / (m). 2 The oxidation rate of the eutectic high-entropy alloy after isothermal oxidation at 1200℃ for 100 h is 0.040-0.046 g / (m). 2 The oxidation rate of the eutectic high-entropy alloy after isothermal oxidation at 1200℃ for 200 h is 0.028-0.035 g / (m). 2 ·h).

7. The eutectic high-entropy alloy according to claim 1, characterized in that, The processing Rockwell hardness of the eutectic high-entropy alloy is 31-35.5 HRC.

8. A method for preparing the eutectic high-entropy alloy according to any one of claims 1-7, characterized in that, The method includes vacuum induction melting and vacuum casting, and the method further includes: The metal raw materials are ground and cleaned to obtain clean raw materials, which include pure metals such as Ni, Co, Cr, Fe, Al, Hf, and Y. Pure metals Ni, Co, Cr, and Fe were loaded into a crucible according to a specific ratio and subjected to vacuum induction melting. The vacuum degree during the melting process was 10. -3 -10 -2 The clean raw material is heated at 5-15 kW for 10-15 minutes, then the power is adjusted to 30-40 kW and maintained for 10-20 minutes. Finally, the power is adjusted to 45-50 kW and the clean raw material is melted at 1550-1600℃. After the clean raw material is melted, the power is reduced to 10-15 kW and waited for 5-10 minutes. Then, high-purity argon gas is introduced to 2000-3000 Pa, and Al particles are added. After stirring for 2 minutes, metallic Y and Hf are added again. Then, the power is increased to 40-45 kW, stirred and heated, and refined at 1500-1600℃ for 5-10 minutes to form an alloy liquid. After the refining process is completed, the power is reduced to 10-20 kW. When the temperature of the alloy liquid drops to 1450-1500℃, vacuum casting is performed. Precision casting is carried out using a ceramic mold shell, with the mold shell baking temperature at 800-1100℃. The vacuum degree of the vacuum casting process is 0.1-5 Pa, and the casting time is 3-5 seconds. After casting, wait 1-10 minutes for the mold shell to be broken open and air-cooled to room temperature in an atmospheric environment. The shell is broken open to obtain a eutectic high-entropy alloy ingot, thus obtaining the eutectic high-entropy alloy.

9. The method according to claim 8, characterized in that, The clean raw materials include 99.95wt% pure Ni blocks, 99.95wt% pure Co blocks, 99.9wt% pure Cr particles, 99.99wt% pure electrolytic iron, 99.99wt% pure Al particles, 99.95wt% pure Hf particles, and 99.9wt% pure Y button ingots after calcium removal; After the clean raw materials are loaded into the crucible according to the specified ratio, the method further includes: closing the furnace door, turning on the mechanical pump to evacuate to below 500 Pa, and then turning on the Roots pump to evacuate to below 10 Pa. -1 Pa-10 -2 Pa, finally turn on the oil diffusion pump to evacuate to 10 Pa. -2 Pa-10 -3 Pa; The precision casting is performed using a cylindrical ceramic mold shell, and the shell is broken to obtain a cylindrical eutectic high-entropy alloy ingot.

10. A casting target material, characterized in that, The casting target material includes the eutectic high-entropy alloy according to any one of claims 1-7, or the casting target material includes the eutectic high-entropy alloy prepared by the method according to claim 8 or 9. The casting target material can be used to prepare the bonding layer of the thermal barrier coating by vacuum arc ion plating process.

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