CrmoTa refractory high-entropy alloy and a method for preparing the same
By using a corrosion solution with a specific ratio of deionized water, nitric acid, hydrofluoric acid, polyethylene glycol, and special additives, the passivation layer of CrMoTa-based refractory high-entropy alloys is destroyed, solving the problems of high hazard and complex operation of traditional corrosion agents, and achieving low-cost and safe microstructure visualization.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XIANGTAN UNIV
- Filing Date
- 2026-04-29
- Publication Date
- 2026-07-14
AI Technical Summary
Existing etchants are difficult to store and highly hazardous, and their operation is cumbersome. They are also difficult to effectively and clearly display the microstructure of CrMoTa-based refractory high-entropy alloys. Traditional etching methods are costly, highly dependent on equipment, and have unsatisfactory results.
A corrosion solution composed of deionized water, nitric acid, hydrofluoric acid, polyethylene glycol, and special additives (such as oxalic acid and ferric chloride) is used to destroy the passivation layer on the alloy surface through a chemical reaction in a specific ratio, revealing clear grain boundaries and grain morphology.
This method achieves low-cost and simple metallographic etching, revealing the microstructure of alloys, reducing detection costs, improving detection efficiency, and using widely available etching solutions with safe operation.
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Figure CN122105407B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of metallographic preparation and testing technology of refractory high-entropy alloys, specifically relating to a CrMoTa-based metallographic etching solution for refractory high-entropy alloys and its preparation method. Background Technology
[0002] Refractory high-entropy alloys are typically composed of a mixture of various high-melting-point metallic elements such as chromium, molybdenum, tantalum, tungsten, niobium, and vanadium in equiatomic or near-equiatomic ratios. These alloys possess excellent high-temperature strength, high hardness, and significant wear and corrosion resistance, and are commonly used in high-temperature components of aerospace engines, nuclear engineering, and structural materials for extreme environments. In particular, CrMoTa-based refractory high-entropy alloys, combining the high melting point of tantalum and molybdenum with the oxidation resistance of chromium, exhibit excellent stability under high-temperature service conditions.
[0003] The microstructure of refractory high-entropy alloys, such as grain size, phase distribution, and grain boundary morphology, significantly affects their yield strength, ductility, and high-temperature creep properties. Therefore, clear observation of the microstructure of refractory high-entropy alloys is of substantial significance. Currently, methods for observing the microstructure of such alloys include electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). However, these methods are costly, highly dependent on equipment, and involve time-consuming and cumbersome sample preparation, making them unsuitable for rapid detection.
[0004] Traditionally, aqua regia solutions are often used for metallographic etching of corrosion-resistant metals. However, because CrMoTa-based refractory high-entropy alloys contain large amounts of highly corrosion-resistant elements such as tantalum, molybdenum, and chromium, their surfaces readily form dense passivation films. Conventional etching solutions are ineffective at corroding the grain boundaries of these alloys, often resulting in failure to etch, uneven corrosion, or pitting that obscures the grain boundaries. Furthermore, aqua regia must be prepared fresh for immediate use, making storage difficult. As a mixture of concentrated nitric and hydrochloric acid, aqua regia is highly volatile and corrosive, releasing toxic gases during operation, posing a significant hazard. For refractory high-entropy alloys with high tantalum content, the corrosive power of conventional aqua regia is often insufficient to uniformly break down the stubborn passivation layer, leading to incomplete grain boundary visibility or the appearance of artifacts. Electrolytic etching can be used, which can improve the etching effect to some extent, but it requires specialized power supply and electrolytic cell equipment, strict control of voltage and current parameters, and troublesome post-treatment of the electrolyte. Improper operation can easily produce non-uniform oxide films or corrosion pits on the alloy surface, severely affecting the accurate observation of the metallographic structure. Therefore, exploring a low-cost, simple-to-operate, efficient, and effective metallographic etching solution for refractory high-entropy alloys has significant engineering application and scientific research value. Summary of the Invention
[0005] To address the aforementioned shortcomings of existing technologies, this invention discloses a CrMoTa-based metallographic etching solution for refractory high-entropy alloys and its preparation method. This solves the problems of existing etchants being difficult to store and highly hazardous, as well as the technical difficulties of existing etching methods being cumbersome and difficult to control.
[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A metallographic etching solution for CrMoTa-based refractory high-entropy alloys is provided, which is composed of deionized water, nitric acid and hydrofluoric acid, polyethylene glycol, and special additives; by mass percentage, the metallographic etching solution contains 16.6~25.4wt% nitric acid, 8.3~12.0wt% hydrofluoric acid, 20~22wt% polyethylene glycol, 0.1~5wt% special additives, and the balance being deionized water; the special additives are at least one of multi-toothed chelating agents and micro-battery potential regulating salts.
[0007] Based on the above technical solution, the present invention can be further improved as follows.
[0008] Furthermore, the multidentate chelating agent is oxalic acid; the micro-battery potential regulating salt is ferric chloride.
[0009] CrMoTa-based refractory high-entropy alloys are rich in tantalum, molybdenum, and chromium. These elements readily form a dense and chemically stable oxide passivation film on the surface. The passivation layer is destroyed by the synergistic chemical action of a specific ratio of hydrofluoric acid, nitric acid, special additives, and deionized water. Nitric acid, as a strong oxidizing agent, increases the redox potential of the solution and promotes oxidation on the metal surface. Fluoride ions in hydrofluoric acid react with refractory metals such as tantalum and molybdenum and their oxides to form water-soluble fluoride complex ions, thereby eliminating the surface passivation film and exposing a new metal matrix. Oxalic acid is mainly used to address the problem of refractory metals readily hydrolyzing and precipitating in acidic aqueous solutions. Polyethylene glycol, as a surfactant, can also reduce the surface tension of the solution, allowing the corrosion solution to adhere more tightly and uniformly to the metal surface, reducing uneven corrosion caused by trapped bubbles. Ferric chloride increases the potential difference between different phases, enhancing the contrast between microstructures. Due to lattice distortion and high interfacial energy at grain boundaries, the chemical reactivity of the grain boundary region is higher than that inside the grains. This causes the aforementioned dissolution reaction to preferentially and rapidly occur at the grain boundaries, resulting in the formation of grooves at the grain boundaries. Deionized water is used in the system to adjust the acid concentration and control the chemical reaction rate, preventing excessive corrosion or oxidation discoloration of the sample surface due to excessive acidity, ultimately allowing the alloy microstructure to be clearly revealed.
[0010] Furthermore, CrMoTa-based refractory high-entropy alloys include CrMoTa ternary alloys, as well as multi-component complex refractory high-entropy alloys formed by doping one or more elements of Al, Ti, and Re on the basis of CrMoTa ternary alloys.
[0011] This invention also discloses a method for preparing a metallographic etching solution for CrMoTa-based refractory high-entropy alloys, the steps of which include: adding deionized water, nitric acid, hydrofluoric acid, polyethylene glycol, and special additives sequentially into a container according to mass percentage, and stirring evenly to obtain the solution.
[0012] This invention also discloses a method for etching CrMoTa-based refractory high-entropy alloys using metallographic etching solutions, the steps of which include:
[0013] S1: The CrMoTa refractory high-entropy alloy sample was successively ground, polished and cleaned;
[0014] S2: The metallographic etching solution is dropped onto the surface of the alloy sample for etching, and the etching time is 1~15s;
[0015] S3: Rinse the surface of the etched alloy sample with deionized water and anhydrous ethanol in sequence and then dry.
[0016] Furthermore, the corrosion time in step S2 is 3~8s.
[0017] The beneficial effects of this invention are:
[0018] The specific ratio of hydrofluoric acid, nitric acid, polyethylene glycol, special additives, and deionized water in the etching solution of this invention can effectively destroy the passivation layer on the alloy surface. (1) Compared with traditional reagents, this etching solution can significantly increase the degree of grain boundary corrosion, clearly showing the grain boundary outline and grain size of the alloy, solving the problem that traditional etching solutions are difficult to treat such alloys or the structure is blurred after corrosion. (2) The hydrofluoric acid, nitric acid, and deionized water used in this etching solution are all conventional chemical reagents in the laboratory, which are widely available and inexpensive. The preparation process is simple and does not require expensive special reagents, which helps to reduce the cost of scientific research and industrial testing and facilitates large-scale promotion and application. (3) The etching method provided by this invention is easy to operate, does not require complex electrolytic polishing equipment or harsh high temperature and high pressure conditions, and has low requirements for testing equipment, which greatly simplifies the preparation process of metallographic samples and improves the efficiency of metallographic structure detection. Attached Figure Description
[0019] Figure 1 This is a 100x magnification metallographic corrosion image of the CrMoTa-based refractory high-entropy alloy in Experiment Example 1.
[0020] Figure 2 This is a 100x magnification metallographic corrosion image of the CrMoTa-based refractory high-entropy alloy in Experiment Example 5.
[0021] Figure 3 This is a 100x magnification metallographic corrosion image of the CrMoTa-based refractory high-entropy alloy in Experiment Example 7.
[0022] Figure 4This is a 100x magnification metallographic corrosion image of the CrMoTa refractory high-entropy alloy in Experiment Example 8. Detailed Implementation
[0023] The specific embodiments of the present invention will be described in detail below with reference to examples.
[0024] Example 1
[0025] A CrMoTa-based refractory high-entropy alloy metallographic etching solution, by mass percentage, contains 21.4 wt% nitric acid (calculated as 65% nitric acid), 11 wt% hydrofluoric acid (calculated as 40% hydrofluoric acid), 21.5 wt% polyethylene glycol, 4 wt% special additives (composed of oxalic acid and ferric chloride), and the balance is deionized water. Its preparation method includes the following steps:
[0026] Under ice-water bath and fume hood conditions, slowly add 27.15 mL of deionized water and 12.6 mL of polyethylene glycol to a polytetrafluoroethylene beaker, mix well, then add 1.2 mL of oxalic acid and 0.6 g of ferric chloride, and stir thoroughly with a polytetrafluoroethylene stir bar until the solid dissolves; then slowly add 9.83 mL of nitric acid and 6.28 mL of hydrofluoric acid in sequence, and stir well to obtain the final product.
[0027] Example 2
[0028] A CrMoTa-based refractory high-entropy alloy metallographic etching solution, by mass percentage, contains 17wt% nitric acid (calculated as 65% nitric acid), 8wt% hydrofluoric acid (calculated as 40% hydrofluoric acid), 20wt% polyethylene glycol, 0.5wt% special additives (composed of oxalic acid and ferric chloride), and the balance is deionized water. Its preparation method includes the following steps:
[0029] Under ice-water bath and fume hood conditions, add 36.35 mL of deionized water and 12.10 mL of polyethylene glycol to a polytetrafluoroethylene beaker and mix well; add 0.19 mL of oxalic acid and 0.10 g of ferric chloride and stir until the solid is completely dissolved; then slowly add 10.0 mL of nitric acid (65%) and 4.72 mL of hydrofluoric acid (40%) and stir well to obtain the final product.
[0030] Example 3
[0031] A CrMoTa-based refractory high-entropy alloy metallographic etching solution, by mass percentage, contains 25wt% nitric acid (calculated as 65% nitric acid), 12wt% hydrofluoric acid (calculated as 40% hydrofluoric acid), 22wt% polyethylene glycol, 5wt% special additives (composed of oxalic acid and ferric chloride), and the balance is deionized water. Its preparation method includes the following steps:
[0032] Under ice-water bath and fume hood conditions, add 12.63 mL of deionized water and 8.80 mL of polyethylene glycol to a polytetrafluoroethylene beaker and mix well; add 0.47 mL of oxalic acid and 0.24 g of ferric chloride and stir until the solid is completely dissolved; then slowly add 10.0 mL of nitric acid (65%) and 4.80 mL of hydrofluoric acid (40%) and stir well to obtain the final product.
[0033] Example 4
[0034] A CrMoTa-based refractory high-entropy alloy metallographic etching solution, by mass percentage, contains 18wt% nitric acid (calculated as 65% nitric acid), 11wt% hydrofluoric acid (calculated as 40% hydrofluoric acid), 21wt% polyethylene glycol, 0.1wt% special additives (composed of oxalic acid and ferric chloride), and the balance is deionized water. Its preparation method includes the following steps:
[0035] Under ice-water bath and fume hood conditions, add 38.92 mL of deionized water and 14.89 mL of polyethylene glycol to a polytetrafluoroethylene beaker and mix well; add 0.04 mL of oxalic acid and 0.02 g of ferric chloride and stir until the solid is completely dissolved; then slowly add 10.0 mL of nitric acid (65%) and 7.59 mL of hydrofluoric acid (40%) and stir well to obtain the final product.
[0036] Example 5
[0037] A CrMoTa-based refractory high-entropy alloy metallographic etching solution, by mass percentage, contains 20wt% nitric acid (calculated as 65% nitric acid), 10wt% hydrofluoric acid (calculated as 40% hydrofluoric acid), 21wt% polyethylene glycol, 3.5wt% special additives (composed of oxalic acid and ferric chloride), and the balance is deionized water. Its preparation method includes the following steps:
[0038] Under ice-water bath and fume hood conditions, add 31.94 mL of deionized water and 13.40 mL of polyethylene glycol to a polytetrafluoroethylene beaker and mix well; add 1.14 mL of oxalic acid and 0.57 g of ferric chloride and stir until the solid is completely dissolved; then slowly add 10.0 mL of nitric acid (65%) and 6.21 mL of hydrofluoric acid (40%) and stir well to obtain the final product.
[0039] Comparative Example 1
[0040] A corrosive liquid, by mass percentage, contains 15 wt% nitric acid (calculated as 65% nitric acid), 7 wt% hydrofluoric acid (calculated as 40% hydrofluoric acid), 21.5 wt% polyethylene glycol, 0.05 wt% special additives (composed of oxalic acid and ferric chloride), and the balance is deionized water. Its preparation method includes the following steps:
[0041] Under ice-water bath and fume hood conditions, add 36.39 mL of deionized water and 12.60 mL of polyethylene glycol to a polytetrafluoroethylene beaker and mix well; add 0.015 mL of oxalic acid and 8 mg of ferric chloride and stir until the solid is completely dissolved; then slowly add 6.89 mL of nitric acid (65%) and 4.00 mL of hydrofluoric acid (40%) and stir well to obtain the final product.
[0042] Comparative Example 2
[0043] A corrosive liquid, by mass percentage, contains 32 wt% nitric acid (calculated as 65% nitric acid), 11 wt% hydrofluoric acid (calculated as 40% hydrofluoric acid), 21.5 wt% polyethylene glycol, 4 wt% special additives (composed of oxalic acid and ferric chloride), and the balance is deionized water. Its preparation method includes the following steps:
[0044] Under ice-water bath and fume hood conditions, slowly add 20.32 mL of deionized water and 12.6 mL of polyethylene glycol to a polytetrafluoroethylene beaker, mix well, then add 1.2 mL of oxalic acid and 0.6 g of ferric chloride, and stir thoroughly with a polytetrafluoroethylene stir bar until the solid dissolves; then slowly add 14.7 mL of nitric acid and 6.28 mL of hydrofluoric acid in sequence, and stir well to obtain the final product.
[0045] Comparative Example 3
[0046] A CrMoTa-based refractory high-entropy alloy metallographic etching solution, by mass percentage, contains 21.4 wt% nitric acid (calculated as 65% nitric acid), 5 wt% hydrofluoric acid (calculated as 40% hydrofluoric acid), 21.5 wt% polyethylene glycol, 4 wt% special additives (composed of oxalic acid and ferric chloride), and the balance is deionized water. Its preparation method includes the following steps:
[0047] Under ice-water bath and fume hood conditions, slowly add 31 mL of deionized water and 12.6 mL of polyethylene glycol to a polytetrafluoroethylene beaker, mix well, then add 1.2 mL of oxalic acid and 0.6 g of ferric chloride, and stir thoroughly with a polytetrafluoroethylene stirring rod until the solid dissolves; then slowly add 9.83 mL of nitric acid and 2.85 mL of hydrofluoric acid in sequence, and stir well to obtain the final product.
[0048] Comparative Example 4
[0049] A CrMoTa-based refractory high-entropy alloy metallographic etching solution, by mass percentage, contains 21.4 wt% nitric acid (calculated as 65% nitric acid), 16 wt% hydrofluoric acid (calculated as 40% hydrofluoric acid), 21.5 wt% polyethylene glycol, 4 wt% special additives (composed of oxalic acid and ferric chloride), and the balance is deionized water. Its preparation method includes the following steps:
[0050] Under ice-water bath and fume hood conditions, slowly add 23.93 mL of deionized water and 12.6 mL of polyethylene glycol to a polytetrafluoroethylene beaker, mix well, then add 1.2 mL of oxalic acid and 0.6 g of ferric chloride, and stir thoroughly with a polytetrafluoroethylene stir bar until the solid dissolves; then slowly add 9.83 mL of nitric acid and 9.13 mL of hydrofluoric acid in sequence, and stir well to obtain the final product.
[0051] Comparative Example 5
[0052] A corrosive liquid, the preparation method of which includes the following steps:
[0053] Under ice-water bath and fume hood conditions, 9 mL of hydrochloric acid (37% by mass) and 3 mL of nitric acid (65% by mass) were added to a beaker, and then the mixture was stirred thoroughly with a polytetrafluoroethylene stirring rod until homogeneous to obtain aqua regia metallographic etching solution.
[0054] Comparative Example 6
[0055] A corrosive liquid, the preparation method of which includes the following steps:
[0056] Under ice-water bath and fume hood conditions, 100 mL of deionized water was added to a beaker, followed by 5 mL of nitric acid (65% by mass) and 3 mL of hydrofluoric acid (40% by mass). The mixture was then stirred thoroughly with a polytetrafluoroethylene stir bar to obtain the Kroll etching solution.
[0057] Experimental Example 1
[0058] The CrMoTaAlTi refractory high-entropy alloy sample was etched with the metallographic etching solution of the CrMoTa-based refractory high-entropy alloy prepared in Example 1, including the following steps:
[0059] S1: The CrMoTa-based refractory high-entropy alloy metallographic sample was cold-mounted with epoxy resin and epoxy resin curing agent. After the mounted sample solidified, it was removed. Then, the sample surface was polished sequentially from coarse to fine using sandpaper of different grits (80#, 240#, 320#, 400#, 800#, 1200#, 2000#) to remove the previous processing scratches. Each time the sandpaper was changed, the sample was rotated 90 degrees so that the polishing directions were intersecting to ensure the surface flatness. Then, it was polished for 2 minutes with 2.5μm water-soluble diamond polishing paste and wool polishing cloth, and then finely polished for 2 minutes with 0.5μm water-soluble diamond polishing paste. When the sample surface showed a mirror gloss and no scratches were observed under an optical microscope, the polishing was considered complete. The polished sample was first placed in anhydrous ethanol for ultrasonic vibration for 5 minutes, and then placed in deionized water for ultrasonic vibration for 5 minutes. Finally, it was removed and dried with a hair dryer.
[0060] S2: Apply the etching solution evenly to the polished sample surface, ensuring that the etching solution completely covers the sample to guarantee the uniformity of etching. The etching time is 3 seconds.
[0061] S3: When the etching solution turns brownish-brown and a matte film appears on the sample surface, rinse quickly with deionized water, then rinse the sample surface with anhydrous ethanol, and dry it with a hair dryer.
[0062] Experimental Example 2
[0063] The CrMoTa-based refractory high-entropy alloy sample was etched with the metallographic etching solution prepared in Example 2, including the following steps:
[0064] S1: The CrMoTa-based refractory high-entropy alloy metallographic sample was cold-mounted with epoxy resin and epoxy resin curing agent. After the mounted sample solidified, it was removed. Then, the sample surface was polished sequentially from coarse to fine using sandpaper of different grits (80#, 240#, 320#, 400#, 800#, 1200#, 2000#) to remove the previous processing scratches. Each time the sandpaper was changed, the sample was rotated 90 degrees so that the polishing directions were intersecting to ensure the surface flatness. Then, it was polished for 1 minute with 2.5μm water-soluble diamond polishing paste and wool polishing cloth, and then finely polished for 1 minute with 0.5μm water-soluble diamond polishing paste. The polishing was completed when the sample surface showed a mirror gloss and no scratches were observed under an optical microscope. The polished sample was first placed in anhydrous ethanol for ultrasonic vibration for 10 minutes, and then placed in deionized water for ultrasonic vibration for 10 minutes. Finally, it was removed and dried with a hair dryer.
[0065] S2: Apply the etching solution evenly to the polished sample surface, ensuring that the etching solution completely covers the sample to guarantee the uniformity of etching. The etching time is 8 seconds.
[0066] S3: When the etching solution turns brownish-brown and a matte film appears on the sample surface, rinse quickly with deionized water, then rinse the sample surface with anhydrous ethanol, and dry it with a hair dryer.
[0067] In Experiments 3-8, the etchant solutions from Comparative Examples 1-6 were used to etch the refractory high-entropy alloy CrMoTaAlTi, and the etching method was the same as in Experiment 1.
[0068] Experimental results
[0069] The etched metallographic sample was observed under a metallographic microscope. Figure 1The image shows the metallographic corrosion pattern of the CrMoTa refractory high-entropy alloy in Experiment 1. The image reveals clear grain boundaries and complete grain morphology, with no obvious over- or under-corrosion, effectively showcasing the microstructure details of the refractory high-entropy alloy. In Experiment 3, due to insufficient dosage of nitric acid, hydrofluoric acid, and special additives, the oxidizing power of the etching solution was insufficient to break the natural passivation state of the CrMoTa refractory high-entropy alloy surface. Under the same corrosion time, the alloy surface hardly reacted, failing to effectively expose grain boundaries and precipitates. Forcibly extending the corrosion time resulted in uneven shallow pits on the surface, and the metallographic structure remained unclear. In Experiment 4, when the nitric acid ratio was too high, the extremely strong oxidizing properties caused Cr, Ta, and other elements on the alloy surface to instantly form a very thick, dense oxide film. At this time, the limited hydrofluoric acid in the system could not dissolve this oxide film in time, leading to a rapid blockage of the corrosion reaction. The sample surface turned yellow and dark, not only failing to clearly etch out grain boundaries but also obscuring the microstructure details. In Experiment 5, the products formed by the oxidation of refractory metals Ta and Mo by nitric acid are extremely difficult to dissolve and require a sufficient amount of fluoride ions for complexation. Under this ratio, due to the low hydrofluoric acid content, the oxide layer formed on the surface cannot be effectively stripped and dissolved. Figure 2 As shown, when the HF ratio decreases, the penetration of the etchant into the passivation film weakens, resulting in most grain boundaries and grains remaining covered by the passivation film. This ultimately manifests as discontinuous grain boundaries, incomplete grains, and a layer of grayish-white reaction products covering the sample surface, making it impossible to clearly etch out the grain morphology and phase boundaries. In Example 6, when the amount of hydrofluoric acid was excessive, the etchant exhibited extremely strong corrosiveness. Fluoride ions not only rapidly corrode grain boundaries but also severely corrode the matrix within the grains. This leads to severe over-corrosion, causing the sample surface to quickly blacken and develop dense, deep pits (pitting corrosion). The original metallographic morphology is completely destroyed, making it unusable for accurate microstructure analysis. Figure 3 The image shows the metallographic corrosion of the CrMoTa refractory high-entropy alloy in Experiment Example 7. Due to the strong inertness of Ta to aqua regia, a passivation film of Ta2O5 is rapidly induced on the surface during the corrosion process. However, other areas without passivation films are corroded by aqua regia, resulting in a large number of black corrosion pits, making it difficult to corrode complete grains. Figure 4 The image shows the metallographic corrosion of the CrMoTa refractory high-entropy alloy in Experiment Example 8, indicating incomplete interfacial corrosion.
[0070] Although specific embodiments of the present invention have been described in detail with reference to examples, they should not be construed as limiting the scope of protection of this patent. Various modifications and variations that can be made by those skilled in the art without inventive effort within the scope described in the claims are still within the scope of protection of this patent.
Claims
1. A metallographic etching solution for CrMoTa-based refractory high-entropy alloys, characterized in that: The metallographic etching solution contains, by mass percentage, 16.6-25.4 wt% nitric acid, 8.3-12.0 wt% hydrofluoric acid, 20-22 wt% polyethylene glycol, 0.1-5 wt% special additives, and the balance being deionized water; the special additives are oxalic acid and ferric chloride.
2. The CrMoTa-based refractory high-entropy alloy metallographic etching solution according to claim 1, characterized in that: The CrMoTa-based refractory high-entropy alloys include CrMoTa ternary alloys and multi-component complex refractory high-entropy alloys formed by doping one or more elements of Al, Ti, and Re on the basis of CrMoTa ternary alloys.
3. The method for preparing the CrMoTa-based refractory high-entropy alloy metallographic etching solution according to any one of claims 1 to 2, characterized in that, The steps include: adding deionized water, polyethylene glycol, nitric acid, hydrofluoric acid, and special additives to a container according to the mass percentage, and stirring evenly to obtain the final product.
4. The etching method of the CrMoTa-based refractory high-entropy alloy metallographic etching solution according to any one of claims 1 to 2, characterized in that, The steps include: S1: The CrMoTa refractory high-entropy alloy sample was successively ground, polished and cleaned; S2: The metallographic etching solution is dropped onto the surface of the alloy sample for etching, and the etching time is 1~15s; S3: Rinse the surface of the etched alloy sample with deionized water and anhydrous ethanol in sequence and then dry.
5. The corrosion method according to claim 4, characterized in that, The etching time in step S2 is 3~8s.