Preparation method of high-entropy high-temperature alloy and high-entropy high-temperature alloy

Abstract

The application is suitable for the field of high-entropy high-temperature alloy, and particularly relates to a preparation method of high-entropy high-temperature alloy and high-entropy high-temperature alloy. The preparation method comprises the following steps: a material preparation step: preparing Co, Ni, Cr, Ti, Al and Cu according to a set component ratio to obtain alloy raw materials; the component ratio of the Co, Ni, Cr, Ti, Al and Cu is Al: 5-7, Co: 35-39, Cr: 22-25, Cu: 4-7, Ni: 21-23 and Ti: 5-7; the alloy raw materials are smelted to form alloy materials; and the alloy materials are subjected to heat treatment, wherein the heat treatment comprises solid solution treatment and quenching at a set temperature. The preparation method of high-entropy high-temperature alloy and high-entropy high-temperature alloy have good mechanical properties of high-entropy high-temperature alloy and have great application prospects.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of high-entropy high-temperature alloys, and particularly relates to a preparation method of a high-entropy high-temperature alloy and the high-entropy high-temperature alloy. BACKGROUND

[0002] Ni-based high-temperature alloys have been widely used in the fields of aviation industry, aerospace industry, petroleum and chemical industry, etc. due to their excellent high-temperature microstructure stability, high-temperature mechanical properties, high-temperature oxidation resistance and hot corrosion resistance.

[0003] The existence of the γ-γ' coherent structure in the alloy can maintain the strength of the alloy under high-temperature conditions. However, due to the limitation of the melting point (1455℃) of the Ni element, the working temperature of the Ni-based high-temperature alloy has reached the limit, and therefore it is necessary to find a new type of high-temperature alloy to meet the development needs of the next generation of aero-engines. The melting point of the Co element is about 40℃ higher than that of the Ni element, and therefore the Co-based high-temperature alloy is considered as a potential material for the next generation of aero-engines. However, the high-temperature mechanical properties of the traditional Co-based high-temperature alloy are poor, and the main strengthening mechanism is carbide precipitation strengthening rather than the L12 strengthening of the Ni-based high-temperature alloy.

[0004] In 2006, Sato et al. found a γ+γ' two-phase coherent structure similar to that in the Ni-based alloy in the Co-Al-W-based alloy, which is the original new Co-based high-temperature alloy, as shown in FIGS. 1(a) to 1(c). In order to further understand the phase composition of the alloy system, Kobayashi et al. used the diffusion couple method to determine the Co-rich side of the ternary isothermal section of the Co-Al-W system at 900℃ in 2009, and the results showed that the L12 phase region is very small after the Co-Al-W system alloy is heat treated at 900℃ for 500 hours, and the phase significantly coarsens and some unwanted impurities appear, which are harmful; if the heat preservation time is further increased to 1500 hours, the L12 phase is observed to be transformed into γ, Co3W (D0 19 ) and CoAl (B2) three phases, which indicates that the L12 phase in the Co-Al-W system alloy is a metastable phase, i.e. the L12 phase has poor thermal stability and low solid solution temperature. In addition, the Co-Al-W system adds a large amount of W element, which can improve the stability of the L12 phase, which significantly increases the density of the alloy, which is not conducive to the application of the alloy in the field of aero-engines. Most importantly, the strength of the alloy at high temperature cannot meet the requirements of commercial application under harsh service conditions.

[0005] In summary, there are two main research ideas for developing new Co-based high-temperature alloys with better performance: one is to develop new Co-based high-temperature alloy systems with γ' phase strengthening mechanism, and the other is to add alloying elements in the existing Co-based high-temperature alloy system to improve its performance.

[0006] Since 2008, the Ishida group has successively found the existence of γ'-Co3(Ga,W) and γ'-Co3(Ge,W) phases in Co-Ga-W-X and Co-Ge-W-X systems, and prepared Co-based superalloys with γ-γ' dual-phase coherent structure in Co-Ga-W-X and Co-Ge-W-X systems. The new Co-based superalloy system has been expanded and extended. Because the Co-W binary system has a metastable γ'-Co3W phase, it can be considered that the addition of Ga / Ge elements can improve the stability of the L12 phase. Compared with the traditional Co-Al-W system high-temperature alloy, the effect of improving the thermal stability of the L12 phase, the solid solution temperature and reducing the density of the alloy is not significant, which greatly limits the industrial application prospect of these two types of alloys, which leads to no follow-up research on Co-Ga-W-X and Co-Ge-W-X system Co-based superalloys.

[0007] In 2015, Makineni et al. prepared Co-Al-Mo system high-temperature alloy, which has a γ-γ' dual-phase coherent structure, and its strengthening phase is γ'-Co3Al. Nb, Mo and Ta elements can improve the stability of the L12 phase. Experimental results show that compared with the traditional Co-Al-W system high-temperature alloy, this kind of alloy has good high-temperature mechanical properties and low density (about 8.5 g·cm -3 ), which makes the W-free Co-based superalloy system get widespread attention. There are still some problems in this kind of alloy, such as insufficient L12 phase solid solution temperature and mechanical properties, etc. Co-Ti-Cr-X, Co-V-Ta-X, Co-V-Nb-X alloy systems with γ+γ' two phases have also been found successively. These alloys do not contain heavy W elements, which can effectively reduce the density of Co-based superalloys, and have great development prospects.

[0008] Traditional Co-based superalloys have only one "main element," and their mechanical properties and melting points are currently approaching their limits. Recently, researchers have developed a Co-Ni-based superalloy based on Co-based superalloys. This alloy exhibits higher L12 phase stability than Co-based superalloys, breaking the traditional limitation of superalloys having only one "main element." High-entropy alloys possess four major effects, leading to unexpected and remarkable properties. Constructing high-entropy alloys with a γ-γ' dual-phase coherent structure organically combines high-entropy alloys with superalloys; these alloys are called high-entropy superalloys and have broad application prospects. High-entropy alloys have a larger number of components, resulting in a much larger compositional space than traditional alloys. Liu et al. successfully developed the AlCoCrFeNiY high-entropy superalloy; however, this alloy is used as a bonding layer between Ni-based superalloys and thermal barrier coatings, and does not belong to the traditional load-bearing structural materials. Currently, research on high-entropy superalloys for aero-engines and gas turbines is limited, and their mechanical properties are far from meeting commercial standards. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a high-entropy high-temperature alloy and a high-entropy high-temperature alloy, which has excellent mechanical properties and great application prospects.

[0010] The technical solution of this invention is: a method for preparing a high-entropy high-temperature alloy, comprising:

[0011] Material preparation steps: Prepare Co, Ni, Cr, Ti, Al, and Cu according to the set composition ratio to obtain alloy raw materials; the composition ratio of Co, Ni, Cr, Ti, Al, and Cu (by weight) is Al: 5-7, Co: 35-39, Cr: 22-25, Cu: 4-7, Ni: 21-23, Ti: 5-7;

[0012] Smelting step: The alloy raw materials are smelted to produce alloy materials;

[0013] Heat treatment steps: The alloy material is subjected to heat treatment, which includes solution treatment and quenching at a set temperature.

[0014] Specifically, before preparing the alloy material, the process includes cleaning Co, Ni, Cr, Ti, Al, and Cu.

[0015] Co, Ni, Cr, Ti, Al, and Cu were placed separately in a cleaning solution for ultrasonic water-resistant cleaning. After cleaning, residual cleaning solution was removed from the material surface. Then, the Co, Ni, Cr, Ti, Al, and Cu materials were weighed according to the set composition ratio using a weighing device.

[0016] Specifically, in the smelting step, an electric arc furnace is used to smelt the alloy raw materials, and the smelting current is between 130A and 420A.

[0017] Specifically, in the smelting step, the material with a high melting point is pre-melted first, and then the material with a low melting point is added;

[0018] During the smelting process, inert gas is introduced into the electric arc melting furnace for gas washing.

[0019] The smelting process includes at least four repeated smelting steps.

[0020] Specifically, the heat treatment includes: aging the alloy material at 880℃-920℃, pre-treating it at 1060-1100℃ for a set time, quickly removing the alloy material from the furnace after the solution treatment, and rapidly quenching and cooling the alloy material in ice water.

[0021] Specifically, the heat treatment includes: aging the alloy material at 900°C, pre-solution treating it at 1080°C for 12 hours, quickly removing the alloy material from the furnace after the solution treatment, and rapidly quenching and cooling the alloy material in cold water with ice, and then subjecting the sample to aging treatment for 48 hours.

[0022] Specifically, the composition ratio of Co, Ni, Cr, Ti, Al, and Cu is Al: 5.5-6.5, Co: 35-39, Cr: 22-25, Cu: 4.5-6.5, Ni: 21-23, and Ti: 5.5-6.5.

[0023] Specifically, the composition ratio of Co, Ni, Cr, Ti, Al, and Cu is Al: 5.8-6.2, Co: 35.5-38.5, Cr: 22.5-24.5, Cu: 4.8-6.2, Ni: 21.8-222.2, and Ti: 5.8-6.2.

[0024] Specifically, the composition ratio of Co, Ni, Cr, Ti, Al, and Cu is Co38Cr23Ni22Al6Ti6Cu5 or Co36Cr24Ni22Al6Ti6Cu6.

[0025] The present invention also provides a high-entropy high-temperature alloy, which adopts the above-described method for preparing a high-entropy high-temperature alloy.

[0026] The present invention provides a method for preparing a high-entropy high-temperature alloy and the high-entropy high-temperature alloy itself. The yield strengths of Co38Cr23Ni22Al6Ti6Cu5 and Co36Cr24Ni22Al6Ti6Cu6 at 700℃ reach 628 MPa and 615 MPa, respectively. The high-entropy high-temperature alloy has excellent mechanical properties and great application prospects. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1(a) is a dark-field image of the Co-9Al-7.5W alloy after aging at 900℃ for 72 hours in the prior art using transmission electron microscopy.

[0029] Figure 1(b) is a selected area electron diffraction pattern of Co-based superalloys in the prior art;

[0030] Figure 1(c) is a metastable isothermal phase diagram of the Co-Al-W ternary system of Co-based superalloys in the prior art at 900℃ on the Co-rich side;

[0031] Figure 2 This is a schematic diagram comparing the compressive strength of a high-entropy superalloy based on the Co-Ni-Cr-Al system and a novel Co-based superalloy with temperature, provided in an embodiment of the present invention.

[0032] Figure 3(a) shows the room temperature compressive stress-strain curves of Ni35Co24Cr24Cu10Ti4Al3, Ni35Co26Cr22Cu10Ti4Al3 and Ni35Co26Cr20Cu10Ti6Al3.

[0033] Figure 3(b) shows the room temperature compressive stress-strain curves of Co37Ni25Cr23Cu5Ti5Al5, Co38Cr23Ni22Al6Ti6Cu5, and Co36Cr24Ni22Al6Ti6Cu6;

[0034] Figure 4 This is a comparison of the compressive strength of high-entropy superalloys in the Co-Ni-Cr-Al system and novel Co-based superalloys as a function of temperature.

[0035] Figure 5(a) shows the XRD patterns of Ni35Co24Cr24Cu10Ti4Al3, Ni35Co26Cr22Cu10Ti4Al3 and Ni35Co26Cr20Cu10Ti6Al3 after solution treatment and aging treatment;

[0036] Figure 5(b) shows the XRD patterns of Co37Ni25Cr23Cu5Ti5Al5, Co38Cr23Ni22Al6Ti6Cu5 and Co36Cr24Ni22Al6Ti6Cu6 after solution treatment and aging.

[0037] Figure 6 shows secondary electron images of the microstructures of the six alloy compositions after solution-aging treatment;

[0038] Figure 7 DSC heating curves for Co37Ni25Cr23Cu5Ti5Al5, Co38Cr23Ni22Al6Ti6Cu5, and Co36Cr24Ni22Al6Ti6Cu6 materials;

[0039] Figure 8 shows the transmission electron microscopy (TEM) analysis results of the solution-treated and aged Co38Cr23Ni22Al6Ti6Cu5 material;

[0040] Figure 9 The results of transmission electron microscopy (TEM) energy dispersive spectroscopy (EDS) analysis of Co38Cr23Ni22Al6Ti6Cu5 material after solution treatment and aging.

[0041] Figure 10 The results of transmission electron microscopy analysis of Co36Cr24Ni22Al6Ti6Cu6 material after solution treatment and aging;

[0042] Figure 11 The results are obtained from transmission electron microscopy (TEM) energy dispersive spectroscopy (EDS) analysis of Co38Cr23Ni22Al6Ti6Cu5 material after solution treatment and aging. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0044] The various specific technical features and embodiments described in the detailed embodiments can be combined in any suitable manner without contradiction. For example, different implementation methods can be formed by combining different specific technical features / embodiments. In order to avoid unnecessary repetition, the various possible combinations of the various specific technical features / embodiments in this invention will not be described separately.

[0045] This invention provides a method for preparing a high-entropy superalloy, comprising:

[0046] Material preparation steps: Prepare Co, Ni, Cr, Ti, Al, and Cu according to the set composition ratio to obtain alloy raw materials; the composition ratio of Co, Ni, Cr, Ti, Al, and Cu is Al: 5-7, Co: 35-39, Cr: 22-25, Cu: 4-7, Ni: 21-23, and Ti: 5-7.

[0047] Smelting step: The alloy raw materials are smelted to produce alloy materials;

[0048] Heat treatment steps: The alloy material is subjected to heat treatment, which includes solution treatment and quenching at a set temperature.

[0049] Specifically, before preparing the alloy material, the process includes cleaning Co, Ni, Cr, Ti, Al, and Cu.

[0050] Co, Ni, Cr, Ti, Al, and Cu are placed separately in a cleaning solution and ultrasonically cleaned in a water-resistant environment for 8 to 12 minutes. After cleaning, the residual cleaning solution on the material surface is removed, and then the Co, Ni, Cr, Ti, Al, and Cu materials are weighed according to the set composition ratio using a weighing device. The cleaning solution can be acetone. In specific applications, the pretreated Co, Ni, Cr, Ti, Al, and Cu are placed in acetone and ultrasonically cleaned in a water-resistant environment for 10 minutes using an ultrasonic cleaner. After cleaning, the acetone residue on the material surface is removed, and finally, the cleaned materials are weighed according to the designed composition ratio using an electronic precision balance.

[0051] Specifically, in the smelting step, an electric arc furnace is used to smelt the alloy raw materials, and the smelting current is between 130A and 420A. More specifically, the smelting current can be between 140A and 400A or between 150A and 400A.

[0052] Specifically, in the smelting step, materials with high melting points are pre-melted first, and then materials with low melting points are added. In specific applications, Cr can be pre-melted first, and then Ti, Co, Ni, Cu, and Al can be added sequentially. Alternatively, Cr, Ti, and Co can be pre-melted first, and then Ni, Cu, and Al can be added sequentially.

[0053] Specifically, during the smelting process, inert gas is introduced into the electric arc melting furnace for gas scrubbing. The pre-proportioned alloy raw materials are smelted in the electric arc melting furnace. To protect the alloy sample from oxidation by atmospheric oxygen, Ar gas is repeatedly used to scrub the furnace cavity to create an inert atmosphere. After scrubbing, the scrubbed Ar gas is extracted and replaced with pure Ar gas. The sample is then smelted in a water-cooled copper crucible, with the smelting current controlled between 150 and 400 A. In this embodiment, the high-melting-point alloy is pre-melted before other metals are added to ensure uniform melting of the sample. This process is repeated at least 4-5 times to obtain the sample (alloy material).

[0054] Specifically, the heat treatment includes: aging the alloy material at 880℃-920℃, pre-treating it at 1060-1100℃ for a set time, quickly removing the alloy material from the furnace after the solution treatment, and rapidly quenching and cooling the alloy material in ice water.

[0055] Specifically, the heat treatment includes: aging the alloy material at 900°C, pre-solution treating it at 1080°C for 12 hours, quickly removing the alloy material from the furnace after the solution treatment, and rapidly quenching and cooling the alloy material in cold water with ice, and then subjecting the sample to aging treatment for 48 hours.

[0056] Specifically, the composition ratio of Co, Ni, Cr, Ti, Al, and Cu is Al: 5.5-6.5, Co: 35-39, Cr: 22-25, Cu: 4.5-6.5, Ni: 21-23, and Ti: 5.5-6.5.

[0057] Specifically, the composition ratio of Co, Ni, Cr, Ti, Al, and Cu is Al: 5.8-6.2, Co: 35.5-38.5, Cr: 22.5-24.5, Cu: 4.8-6.2, Ni: 21.8-22.2, and Ti: 5.8-6.2.

[0058] Specifically, the composition ratio of Co, Ni, Cr, Ti, Al, and Cu is Co38Cr23Ni22Al6Ti6Cu5 and Co36Cr24Ni22Al6Ti6Cu6.

[0059] Samples aged at 900℃ require prior solution treatment at 1080℃ for 12 hours. After solution treatment, the samples are quickly removed from the furnace and rapidly quenched in ice water. The purpose of quenching is to maintain the microstructure of the alloy sample at high temperatures, and then the samples are aged for 48 hours.

[0060] High-entropy superalloys typically operate at high temperatures. To explore the influence of temperature on the mechanical properties of high-entropy superalloy materials, compression tests were conducted on samples at 500℃, 600℃, 700℃, 800℃, and 900℃. The room-temperature based high-temperature strength of the two novel materials developed in this work is superior to that of most novel Co-based superalloys. For high-entropy superalloys in the Co-Ni-Cr-Al system, the high-temperature compressive strength of the material decreases continuously with increasing temperature. Specifically, at 700℃, the high-temperature compressive strength of the alloy shows a slight rebound, with the yield strengths of Co38Cr23Ni22Al6Ti6Cu5 and Co36Cr24Ni22Al6Ti6Cu6 reaching 628 MPa and 615 MPa, respectively. To more clearly describe the relationship between the compressive strength of high-entropy superalloys and ambient temperature, two materials with the best room-temperature mechanical properties were selected from the above six materials to test their high-temperature compressive properties. The relationship between the high-temperature compressive yield strength of Co38Cr23Ni22Al6Ti6Cu5 and Co36Cr24Ni22Al6Ti6Cu6 and temperature is as follows: Figure 2 As shown, although Co36Cr24Ni22Al6Ti6Cu6 material has a higher room temperature compressive strength than Co38Cr23Ni22Al6Ti6Cu5 material, Co38Cr23Ni22Al6Ti6Cu5 material has a higher high temperature compressive strength. In other words, Co38Cr23Ni22Al6Ti6Cu5 material is more suitable for service under high temperature conditions.

[0061] The most important property of high-entropy superalloys in the Co-Ni-Cr-Al system is its mechanical properties. First, the room temperature compressive properties of six materials were tested, as shown in Figures 3(a) and 3(b), which depict the room temperature compressive stress-strain curves of the Co-Ni-Cr-Al system. As shown in Figure 3(b), the Co36Cr24Ni22Al6Ti6Cu6 material exhibits the highest room temperature yield strength, reaching 872 MPa; the Co38Cr23Ni22Al6Ti6Cu5 material has the second highest yield strength, reaching 824 MPa; while the Co37Ni25Cr23Cu5Ti5Al5 material has a yield strength of 758 MPa. In contrast, as shown in Figure 3(a), the yield strengths of Ni35Co24Cr24Cu10Ti4Al3, Ni35Co26Cr22Cu10Ti4Al3, and Ni35Co26Cr20Cu10Ti6Al3 materials are relatively low, only 522 MPa, 578 MPa, and 466 MPa, respectively. At high temperatures, the room temperature yield strength of these materials would only be lower, which clearly does not meet the actual service requirements of high-entropy high-temperature materials. Therefore, the mechanical properties of Ni35Co24Cr24Cu10Ti4Al3, Ni35Co26Cr22Cu10Ti4Al3, and Ni35Co26Cr20Cu10Ti6Al3 high-entropy high-temperature alloys will not be analyzed further.

[0062] High-entropy superalloys typically operate at high temperatures. To investigate the effect of temperature on the mechanical properties of high-entropy superalloy materials, compression tests were conducted on samples at 500℃, 600℃, 700℃, 800℃, and 900℃. For Co-Ni-Cr-Al system high-entropy superalloys, the high-temperature compressive strength of the material showed a continuous decreasing trend with increasing temperature. In particular, at 700℃, the high-temperature compressive strength of the alloy showed a slight rebound, with the yield strengths of Co38Cr23Ni22Al6Ti6Cu5 and Co36Cr24Ni22Al6Ti6Cu6 reaching 628 MPa and 615 MPa, respectively.

[0063] To more clearly describe the relationship between the compressive strength of high-entropy superalloys and ambient temperature, two materials with the best room-temperature mechanical properties were selected from the above six materials to test their high-temperature compressive properties. The relationship between the high-temperature compressive yield strength of Co38Cr23Ni22Al6Ti6Cu5 and Co36Cr24Ni22Al6Ti6Cu6 and temperature is as follows: Figure 4 As shown, Figure 4This is a comparison of the compressive strength of high-entropy superalloys in the Co-Ni-Cr-Al system and novel Co-based superalloys as a function of temperature. It can be observed that although Co36Cr24Ni22Al6Ti6Cu6 has a higher room-temperature compressive strength than Co38Cr23Ni22Al6Ti6Cu5, Co38Cr23Ni22Al6Ti6Cu5 has a higher high-temperature compressive strength. In other words, Co38Cr23Ni22Al6Ti6Cu5 is more suitable for service under high-temperature conditions.

[0064] To determine the phase composition of the above materials, X-ray diffraction phase analysis (XRD) was performed on each sample, and the results are shown in Figure 5(a) and Figure 5(b).

[0065] Figure 5(a) shows the XRD patterns of Ni35Co24Cr24Cu10Ti4Al3, Ni35Co26Cr22Cu10Ti4Al3, and Ni35Co26Cr20Cu10Ti6Al3 after solution treatment and aging. Figure 5(b) shows the XRD patterns of Co37Ni25Cr23Cu5Ti5Al5, Co38Cr23Ni22Al6Ti6Cu5, and Co36Cr24Ni22Al6Ti6Cu6 after solution treatment and aging. Combining the phase volume fraction-temperature curves and XRD patterns, it can be seen that for Ni35Co24Cr24Cu10Ti4Al3, Ni35Co26Cr22Cu10Ti4Al3 and Ni35Co26Cr20Cu10Ti6Al3 materials, the main phase structures are Ni3Al with an FCC+L12 structure and Cu with an FCC structure. Among them, Ni3Al is the strengthening phase of the above three alloys, while Cu will reduce the strength and melting point of these three alloys.

[0066] For Co37Ni25Cr23Cu5Ti5Al5, Co38Cr23Ni22Al6Ti6Cu5, and Co36Cr24Ni22Al6Ti6Cu6 materials, the main phase structures are (Ni, Co)3Al and (Ni, Co)3Ti with FCC+L12 structures, and Cu with FCC structures. Compared with Ni35Co24Cr24Cu10Ti4Al3, Ni35Co26Cr22Cu10Ti4Al3, and Ni35Co26Cr20Cu10Ti6Al3 materials, as shown in Figure 5.20, these three materials produce less Cu, which reduces the harmful effects of excessive Cu precipitation on the strength and melting point of these three alloys.

[0067] Figure 6 shows secondary electron images of the microstructures of six alloys after solution treatment and aging. The six alloys are: (a) Ni35Co24Cr24Cu10Ti4Al3; (b) Ni35Co26Cr22Cu10Ti4Al3; (c) Ni35Co26Cr20Cu10Ti6Al3; (d) Co37Ni25Cr23Cu5Ti5Al5; (e) Co38Cr23Ni22Al6Ti6Cu5; and (f) Co36Cr24Ni22Al6Ti6Cu6. All alloys exhibited an FCC+L12 coherent dual-phase structure, which significantly improves the alloy's strength. Figure 6 The medium-dark gray color indicates an FCC structure, while the blocky light gray color indicates an L12 structure. Notably, the Ni35Co24Cr24Cu10Ti4Al3, Ni35Co26Cr22Cu10Ti4Al3, Ni35Co26Cr20Cu10Ti6Al3, and Co36Cr24Ni22Al6Ti6Cu6 high-entropy superalloys exhibit black microstructures. Combined with the XRD analysis results above, it is easy to identify these black microstructures as elemental Cu. Although Cu has a stabilizing effect on the L12 phase, excessive Cu will lower the melting point and strength of the alloy, which is undoubtedly detrimental to the Co-Ni-Cr-Al system of high-entropy superalloys.

[0068] To investigate the high-entropy mechanical properties of high-entropy superalloys in the Co-Ni-Cr-Al system and to verify the phase diagram calculations predicting the solution temperature of the L12 phase, SEM images show that Ni35Co24Cr24Cu10Ti4Al3, Ni35Co26Cr22Cu10Ti4Al3, and Ni35Co26Cr20Cu10Ti6Al3 contain a large amount of elemental Cu, which significantly reduces the solution temperature and melting point of the L12 phase. Therefore, the solution temperature and melting point of the L12 phase were not tested for these three materials.

[0069] Figure 7 The DSC heating curves for Co37Ni25Cr23Cu5Ti5Al5, Co38Cr23Ni22Al6Ti6Cu5, and Co36Cr24Ni22Al6Ti6Cu6 materials are shown below. Figure 7The DSC heating curves for each alloy composition are presented. The figures show that the L12 phase solution temperature of Co37Ni25Cr23Cu5Ti5Al5 is 1035℃, and its melting point is 1217℃; the L12 phase solution temperature of Co38Cr23Ni22Al6Ti6Cu5 is 1018℃, and its melting point is 1220℃; and the L12 phase solution temperature of Co36Cr24Ni22Al6Ti6Cu6 is 998℃, and its melting point is 1211℃. This further demonstrates that Cu lowers the L12 phase solution temperature and melting point.

[0070] In comparison, the phase diagram calculations predict the L12 phase solution temperatures of Co37Ni25Cr23Cu5Ti5Al5, Co38Cr23Ni22Al6Ti6Cu5, and Co36Cr24Ni22Al6Ti6Cu6 materials to be 1030℃, 1100℃, and 1030℃, respectively, while their melting points are 1280℃, 1290℃, and 1290℃. This demonstrates that the phase diagram calculations accurately predict the L12 phase solution temperatures and melting points of each material, eliminating the need for corrections to the heat treatment parameters.

[0071] The previous analysis results show that the microstructure of Co38Cr23Ni22Al6Ti6Cu5 is a γ-γ' two-phase coherent structure, exhibiting excellent compressive properties and no excessive Cu precipitation. To further investigate the microstructure and elemental distribution of this material, and thus analyze the strengthening mechanism of the Co-Ni-Cr-Al system high-entropy superalloy, this study aims to further investigate these characteristics.

[0072] Figure 8 shows the transmission electron microscopy (TEM) analysis results of the Co38Cr23Ni22Al6Ti6Cu5 material after solution treatment and aging, where (a) is the dark-field image and (b) is the selected area electron diffraction (SADP) image. Combining the TEM dark-field image and the SADP image, it can be seen that γ' in this alloy has a lattice structure, has an L12 crystal structure, and is uniformly distributed in the γ matrix phase.

[0073] Figure 9 shows the transmission electron microscopy (TEM) energy dispersive spectroscopy (EDS) results of the solution-treated and aged Co38Cr23Ni22Al6Ti6Cu5 material. Figure 9Transmission electron microscopy (TEM) energy dispersive spectroscopy analysis of solution-aged Co38Cr23Ni22Al6Ti6Cu5 material revealed that Ni, Al, Ti, and Cu elements tend to be distributed in the γ' strengthening phase, while Co and Cr tend to be distributed in the γ matrix phase. Cr can improve the corrosion resistance of the Co-Ni-Cr-Al high-entropy superalloy matrix and reduce the mismatch of the γ-γ' coherent structure. The high volume fraction of the γ' phase in this alloy, containing abundant Al and Ti elements, contributes to the lightweighting of the Co-Ni-Cr-Al high-entropy superalloy. The addition of Ni generates the γ'-(Ni, Co)3Al phase, which helps improve the stability of the γ'-Co3Al phase. Cu also has a stabilizing effect on the L12 phase, but excessive Cu will reduce the mechanical properties, melting point, and solution temperature of the L12 phase in the Co-Ni-Cr-Al high-entropy superalloy.

[0074] To further analyze the composition of the harmful phase, Figure 10 Transmission electron microscopy (TEM) analysis results of solution-aged Co36Cr24Ni22Al6Ti6Cu6 material: dark-field image and selected area electron diffraction (SADP) pattern. The results show that the γ' phase in this alloy exhibits a lattice-like structure with an L12 crystal structure and is uniformly distributed within the γ matrix phase. The precipitated harmful phases are distributed in both the γ matrix phase and the γ' phase.

[0075] Figure 11 The results are from transmission electron microscopy (TEM) energy dispersive spectroscopy (EDS) analysis of Co38Cr23Ni22Al6Ti6Cu5 material after solution treatment and aging. Ni, Al, Ti, and a small amount of Cu used to stabilize the L12 phase tend to be distributed in the γ' strengthening phase, while Co and Cr tend to be distributed in the γ matrix phase. In particular, the excess Cu exhibits concentrated precipitation, distributed in both the γ matrix and γ' phases. Combined with the previous XRD and TEM analysis results, the harmful phase is elemental Cu.

[0076] The present invention also provides a high-entropy high-temperature alloy, which adopts the above-described method for preparing a high-entropy high-temperature alloy.

[0077] The present invention provides a method for preparing a high-entropy high-temperature alloy and the high-entropy high-temperature alloy thereof, which has excellent mechanical properties and great application prospects.

[0078] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a high-entropy superalloy, characterized in that, include: Material preparation steps: Prepare Co, Ni, Cr, Ti, Al, and Cu according to the set composition ratio to obtain alloy raw materials. By weight, the composition ratio of Co, Ni, Cr, Ti, Al, and Cu is Al: 5-7, Co: 35-39, Cr: 22-25, Cu: 4-7, Ni: 21-23, and Ti: 5-7. Smelting step: The alloy raw materials are smelted to produce alloy materials; Heat treatment steps: The alloy material is subjected to heat treatment, which includes solution treatment and quenching at a set temperature.

2. The method for preparing a high-entropy superalloy as described in claim 1, characterized in that, Before preparing the alloy material, the process includes cleaning the Co, Ni, Cr, Ti, Al, and Cu components. Co, Ni, Cr, Ti, Al, and Cu were placed in a cleaning solution for ultrasonic water-resistant cleaning. After cleaning, the residual cleaning solution on the material surface was removed, and then the Co, Ni, Cr, Ti, Al, and Cu materials were weighed according to the set composition ratio using a weighing device.

3. The method for preparing a high-entropy superalloy as described in claim 1, characterized in that, In the smelting step, an electric arc furnace is used to smelt the alloy raw materials, and the smelting current is between 130A and 420A.

4. The method for preparing a high-entropy superalloy as described in claim 3, characterized in that, In the smelting step, the material with a high melting point is pre-melted first, and then the material with a low melting point is added. During the smelting process, inert gas is introduced into the electric arc melting furnace for gas washing. The smelting process involves at least four repeated turnings.

5. The method for preparing a high-entropy superalloy as described in claim 1, characterized in that, The heat treatment includes: aging the alloy material at 880℃-920℃, pre-solution treatment at 1060-1100℃ for a set time, quickly removing the alloy material from the furnace after solution treatment, and rapidly quenching and cooling the alloy material in ice water.

6. The method for preparing a high-entropy superalloy as described in claim 5, characterized in that, The heat treatment includes: aging the alloy material at 900°C, pre-solution treating it at 1080°C for 12 hours, quickly removing the alloy material from the furnace after solution treatment, quenching the alloy material in cold water with ice, and then aging the sample for 48 hours.

7. The method for preparing a high-entropy superalloy as described in claim 1, characterized in that, By weight, the composition ratio of Co, Ni, Cr, Ti, Al, and Cu is Al: 5.5-6.

5. ， Co: 35-39 ， Cr: 22-25, Cu: 4.5-6.5, Ni: 21-23, Ti: 5.5-6.

5.

8. The method for preparing a high-entropy superalloy as described in claim 1, characterized in that, By weight, the composition ratio of Co, Ni, Cr, Ti, Al, and Cu is Al: 5.8-6.

2. ， Co: 35.5-38.5 ， Cr: 22.5-24.5, Cu: 4.8-6.2, Ni: 21.8-22.2, Ti: 5.8-6.

2.

9. A method for preparing a high-entropy superalloy as described in any one of claims 1 to 8, characterized in that, By weight, the composition ratio of Co, Ni, Cr, Ti, Al, and Cu is Co38Cr23Ni22Al6Ti6Cu5 or Co36Cr24Ni22Al6Ti6Cu6.

10. A high-entropy superalloy, characterized in that, It is prepared by any one of the methods for preparing a high-entropy superalloy as described in any one of claims 1 to 9.

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