EBSD sample of AlMoNbTiV series refractory high-entropy alloy and preparation method

Abstract

The invention discloses an EBSD sample of an AlMoNbTiV-series refractory high-entropy alloy and a preparation method. The preparation method comprises the following steps: cutting a refractory high-entropy alloy sample to be prepared; carrying out step-by-step grinding and mechanical polishing on the EBSD analysis surface of the sample by adopting abrasive paper so as to enable the surface to be smooth and bright, cleaning and blow-drying for later use; preparing an electrolytic polishing solution composed of a methanol solution and a sulfuric acid solution; the refractory high-entropy alloy sample is used as an anode and connected with the positive electrode of a power supply; stainless steel or other steel sheets serve as a cathode and are connected with the negative electrode of the power source, and the refractory high-entropy alloy sample is subjected to electrolytic polishing; and after electric polishing is completed, the refractory high-entropy alloy EBSD sample is rapidly cleaned and blow-dried, and the refractory high-entropy alloy EBSD sample is obtained. The EBSD sample prepared through the method is easy to operate, low in environment temperature requirement and high in resolution rate, expensive equipment such as vibration polishing equipment is not needed, the high resolution rate of the EBSD sample is guaranteed, and low-cost and high-efficiency preparation of the AlMoNbTiV series refractory high-entropy alloy EBSD sample is achieved.

Description

Technical Field

[0001] This invention belongs to the field of metal material sample preparation technology, specifically relating to an EBSD sample of an AlMoNbTiV refractory high-entropy alloy and its preparation method. Background Technology

[0002] Electron backscattered diffraction (EBSD) is a microscopic characterization method based on scanning electron microscopy. During testing, the electron beam emitted by the scanning electron microscope acts on the surface of a tilted sample, exciting a Kikuchi pattern of backscattered diffraction. By collecting and calibrating this Kikuchi pattern, functions such as phase identification, orientation relationship analysis, and dislocation distribution characterization can be achieved. Currently, this technology has become an important tool in the field of material microstructure observation and crystal orientation analysis.

[0003] AlMoNbTiV refractory high-entropy alloys possess high melting points, high hardness, and excellent high-temperature strength properties, with applicable temperatures reaching 1273K and higher. This successfully overcomes the performance bottlenecks of traditional high-temperature alloys, thus showing broad application prospects in key fields such as aerospace, energy, and military. The mechanical properties of these alloys largely depend on crystallographic parameters such as phase composition and content, grain size, and texture orientation. For the analysis of these parameters, EBSD technology, with a spatial resolution of up to 0.1 μm, can accurately characterize these crystallographic features.

[0004] EBSD testing places extremely high demands on sample surface quality. Defects such as unevenness, raised surfaces, scratches, or stress layers on the sample surface make it difficult to obtain clear diffraction patterns, thus hindering the effective interpretation of crystallographic information. Currently, common methods for preparing EBSD samples of refractory high-entropy alloys include vibration polishing, electropolishing, and ion polishing. Vibration polishing requires pre-mounting and mechanical polishing of the sample, and this method is time-consuming and has a cumbersome overall process. Ion polishing is prone to ion implantation damage, causing changes in the alloy's crystal structure, and suffers from high equipment costs and low sample preparation efficiency. Electropolishing, utilizing electrochemical action, can effectively remove stress layers from the sample surface, offering advantages such as shorter preparation time and lower cost. However, for different processing targets, the electrolyte ratio and electrolytic parameters required for electropolishing are difficult to determine precisely. This can lead to poor polishing results and excessive corrosion, further reducing sample preparation efficiency and increasing time and economic costs.

[0005] Existing technology 1 (CN117969572A) discloses a method for preparing refractory high-entropy alloy EBSD samples. Although this method has achieved certain results in the preparation of refractory high-entropy alloy samples, it has shortcomings in sample preparation efficiency. First, the refractory high-entropy alloy samples need to be hot-mounted, which increases the economic cost; second, it uses chemical polishing slurry for polishing, and the polishing slurry needs to be continuously added dropwise for 30-60 minutes during the polishing process, which increases the time cost. In addition, the time point phenomenon at the completion of polishing is not described clearly, making it difficult to determine the surface state of qualified EBSD samples.

[0006] Existing technology 2 (CN118777342A) discloses a high-resolution EBSD sample preparation method for CoCrFeNi high-entropy alloys. Although this system does not belong to the category of refractory high-entropy alloys, its EBSD preparation method still has reference value. A certain difficulty in the preparation process is that the temperature parameters for electrolytic polishing of this alloy need to be maintained between -30℃ and -10℃, which undoubtedly increases the operational difficulty, and the time point phenomenon at the completion of polishing is not clearly described. Summary of the Invention

[0007] In order to overcome the above-mentioned problems in the prior art, the present invention provides an EBSD sample of AlMoNbTiV refractory high-entropy alloy and its preparation method, which is used to solve the above-mentioned problems in the prior art.

[0008] A method for preparing EBSD samples of AlMoNbTiV refractory high-entropy alloys, the method comprising the following steps: S1. Obtain the sample to be prepared from the AlMoNbTiV refractory high-entropy alloy; S2. The sample to be prepared is ground with sandpaper and mechanically polished, then cleaned and dried before use; S3. Prepare an electrolytic polishing solution consisting of a methanol solution and a concentrated sulfuric acid solution; S4. Using the dried sample as the anode and connected to the positive terminal of the power supply; using a steel sheet as the cathode and connected to the negative terminal of the power supply, immerse the sample in the electrolytic polishing solution for electrolytic polishing. S5. After electropolishing, the sample to be prepared is cleaned and dried to obtain the EBSD sample of AlMoNbTiV refractory high-entropy alloy.

[0009] In addition to the aspects and any possible implementations described above, a further implementation is provided in which, in S1, an electrical discharge wire cutting device is used to cut and obtain the AlMoNbTiV refractory high entropy alloy sample to be prepared. The sample to be prepared is a cylinder with its upper surface serving as the surface to be observed. Its diameter is less than 15 mm, and the height of the cylinder is 10 mm to 15 mm.

[0010] In addition to the aspects and any possible implementations described above, a further implementation is provided in which, in S2, the surface to be observed of the sample to be prepared is successively ground with 60#, 240#, 400#, 800#, 1000# and 2000# sandpaper until scratches in a uniform direction are visible to the naked eye, and the remaining surfaces are ground smooth with 60# sandpaper.

[0011] In addition to the aspects and any possible implementations described above, a further implementation is provided in which, in S2, the mechanical polishing uses a water-soluble diamond polishing paste, the rotation speed is 1500 rpm, and the polishing time is 20 to 30 minutes.

[0012] In addition to the aspects described above and any possible implementation, a further implementation is provided in which, in S3, the volume percentage of methanol solution in the electrolytic polishing solution is 80-95%, and the volume percentage of concentrated sulfuric acid solution is 5-20%.

[0013] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the steel sheet is a stainless steel sheet or other steel sheet.

[0014] In addition to the aspects and any possible implementations described above, a further implementation is provided in which, in S4, the temperature of the electrolytic polishing solution is room temperature (20-25°C), the polishing voltage is 10-20V, the polishing current is 5A, and the polishing time is 2-4s.

[0015] In addition to the aspects and any possible implementations described above, a further implementation is provided in which, in S4, the condition for determining that the sample to be prepared has completed electropolishing is that the light gray epidermis of the analytical surface has peeled off.

[0016] In addition to the aspects and any possible implementations described above, a further implementation is provided in which, in S5, the process of cleaning and drying the sample to be prepared after electropolishing is carried out by rinsing with clean water and ultrasonically cleaning the surface of the alloy sample with anhydrous ethanol, and then using a blower to dry the surface of the AlMoNbTiV refractory high entropy alloy sample along one side with hot air.

[0017] The present invention also provides an EBSD sample of an AlMoNbTiV refractory high-entropy alloy, wherein the EBSD sample is obtained by the preparation method described above.

[0018] Beneficial effects of the present invention The present invention discloses a method for preparing EBSD samples of AlMoNbTiV refractory high-entropy alloys, comprising: S1. obtaining an AlMoNbTiV refractory high-entropy alloy sample to be prepared; S2. grinding and mechanically polishing the sample to be prepared with sandpaper, and then cleaning and drying it for later use; S3. preparing an electrolytic polishing solution composed of methanol solution and concentrated sulfuric acid solution; S4. using the dried sample to be prepared as the anode, connected to the positive terminal of a power supply; using a steel sheet as the cathode, connected to the negative terminal of a power supply, immersing the sample to be prepared in the electrolytic polishing solution for electrolytic polishing; S5. cleaning and drying the sample after electropolishing to obtain an EBSD sample of the AlMoNbTiV refractory high-entropy alloy. This method, under room temperature conditions, completes the preparation of the EBSD sample by grinding the cut AlMoNbTiV refractory high-entropy alloy sample, followed by mechanical polishing, electrolytic polishing, and finally ultrasonic cleaning and drying. The AlMoNbTiV refractory high-entropy alloy EBSD samples prepared using this invention are not only simple to operate, time-saving, and do not require expensive equipment, but also ensure a high calibration rate on the EBSD sample surface by observing the time node phenomenon at the completion of electropolishing. This achieves efficient and low-cost preparation of AlMoNbTiV refractory high-entropy alloy EBSD samples. The original calibration rate of the samples prepared by this invention can reach over 95%, accurately reflecting the microstructure and orientation information of the AlMoNbTiV refractory high-entropy alloy.

[0019] Compared with the prior art, the present invention has the following advantages: 1. This invention involves grinding a cut AlMoNbTiV refractory high-entropy alloy sample, followed by mechanical polishing and electrolytic polishing, and finally ultrasonic cleaning and drying to obtain the target EBSD sample. This preparation method is both efficient and rapid, with a high sample preparation success rate; the original pattern calibration rate of the corresponding EBSD sample can reach over 95%.

[0020] 2. Compared with the vibration polishing method, the sample preparation method of the present invention does not require additional sample mounting operations and is less likely to introduce new surface defects. It not only significantly shortens the sample preparation time, but also keeps the Kikuchi flower pattern calibration rate at a better level. Compared with ion polishing, the method of the present invention has lower requirements for polishing equipment and can achieve a significant reduction in sample preparation costs.

[0021] 3. Furthermore, the electropolishing solution provided by this invention is not only highly efficient, but its ambient temperature is also easy to control. At room temperature, the corrosive properties of the methanol-concentrated sulfuric acid mixture effectively improve polishing efficiency. By observing the time point phenomenon at the completion of electropolishing, the residual stress layer generated during grinding and mechanical polishing can be effectively eliminated. Simultaneously, by optimizing the electropolishing solution ratio and electropolishing parameters, the reaction rate between the electropolishing solution and the surface of the AlMoNbTiV refractory high-entropy alloy sample can be buffered, thereby preventing excessive corrosion and significantly improving the surface finish of the sample, ultimately obtaining a uniform surface. Attached Figure Description

[0022] Figure 1 This is a flowchart of the method of the present invention; Figure 2 This is a grain orientation distribution diagram of the as-cast AlMoNbTiV refractory high-entropy alloy EBSD sample prepared in Example 1 of the present invention; Figure 3 This is a grain orientation distribution diagram of the hot isostatically pressed AlMoNbTiV refractory high entropy alloy EBSD sample prepared in Example 2 of the present invention; Figure 4 To compare the grain orientation distribution of AlMoNbTiV-based cast refractory high-entropy alloy samples under a polishing voltage of 5V; Figure 5 The calibration curve of the analytical surface of the AlMoNbTiV system hot isostatic pressing refractory high entropy alloy sample of Comparative Example 5 is shown. Figure 6 This is a schematic diagram of the component connections for electropolishing according to the present invention. Detailed Implementation

[0023] To better understand the technical solution of this invention, the content of this invention includes, but is not limited to, the specific embodiments described below. Similar technologies and methods should be considered within the scope of protection of this invention. To make the technical problems to be solved, the technical solutions, and advantages of this invention clearer, a detailed description will be provided below in conjunction with the accompanying drawings and specific embodiments.

[0024] It should be understood that the embodiments described in this invention are merely some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0025] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0026] This invention provides a method for preparing EBSD samples of AlMoNbTiV refractory high-entropy alloys, the method comprising the following steps: S1. Obtain the sample to be prepared from the AlMoNbTiV refractory high-entropy alloy; S2. The sample to be prepared is ground with sandpaper and mechanically polished, then cleaned and dried before use; S3. Prepare an electrolytic polishing solution consisting of a methanol solution and a concentrated sulfuric acid solution; S4. Using the dried sample as the anode and connected to the positive terminal of the power supply; using a steel sheet as the cathode and connected to the negative terminal of the power supply, immerse the sample in the electrolytic polishing solution for electrolytic polishing. S5. After electropolishing, the sample to be prepared is cleaned and dried to obtain the EBSD sample of AlMoNbTiV refractory high-entropy alloy.

[0027] Specifically, such as Figure 1 As shown, the preparation process of the present invention is as follows: A method for preparing EBSD samples of AlMoNbTiV refractory high-entropy alloys includes the following steps: Step 1: Use an electrical discharge wire cutting device to cut the AlMoNbTiV refractory high-entropy alloy sample to be prepared; Step 2: Grind the sample to be prepared with sandpaper to remove the surface oxide layer generated during the wire cutting process; Step 3: The ground AlMoNbTiV refractory high-entropy alloy is mechanically polished to make its surface smooth and light gray, and then cleaned and dried for later use. Step 4: Prepare an electrolytic polishing solution consisting of methanol solution and concentrated sulfuric acid solution; Step 5: Using the AlMoNbTiV refractory high-entropy alloy sample as the anode, connected to the positive terminal of the power supply; and using stainless steel or other steel sheets as the cathode, connected to the negative terminal of the power supply, electrolytically polish the refractory high-entropy alloy sample. The material requirements for the steel sheets are not high, as long as they are conductive; therefore, stainless steel or other steel sheets can meet the requirements and form the anode and cathode with the sample. Specifically... Figure 6 As shown, an AlMoNbTiV refractory high-entropy alloy sample is used as the anode, designated as alloy sample 6, and connected to the positive terminal of power supply 1 via a conductive clamp such as metal tweezers 5. A stainless steel sheet or other conductive steel sheet 7 is used as the cathode, with its junction connected to the negative terminal of power supply 1 and placed at the bottom of the electrolytic cell or glass dish 3. Electrolytic polishing solution is poured into the electrolytic cell or glass dish 3, with the liquid level simultaneously submerging the upper surface of the cathode steel sheet 7 and the analytical surface of the alloy sample 6 to be polished. During polishing, the analytical surface of the alloy sample 6 is vertically immersed downwards in the electrolytic polishing solution without contacting the steel sheet 7. Electrolytic polishing is achieved through electrochemical action to remove residual stress from the analytical surface of the alloy sample 6. Step 6: After the AlMoNbTiV refractory high-entropy alloy has been electropolished, it is quickly cleaned and dried to obtain the EBSD sample of the AlMoNbTiV refractory high-entropy alloy.

[0028] Furthermore, in step one, the cut AlMoNbTiV refractory high-entropy alloy is used as a cylindrical sample to be prepared. The upper or lower surface of the cylinder can be used as the analytical surface, and the diameter is less than 15 mm, and the height of the cylinder is 10 mm to 15 mm.

[0029] Furthermore, in step two, the cut AlMoNbTiV refractory high-entropy alloy is polished on its surface using 60#, 240#, 400#, 800#, 1000#, and 2000# sandpaper respectively, until scratches in a uniform direction are visible to the naked eye. Specifically, the surface is first polished with 60# sandpaper to remove oxides from the cut sample surface; then 240#, 400#, 800#, 1000#, and 2000# sandpaper are used to remove stress generated by each previous polishing pass. After polishing with 2000# sandpaper, fine scratches in a uniform direction are visible to the naked eye on the sample surface. At this point, the stress on the surface is relatively low, indicating that the stress layer on the surface has been thinned. Diamond polishing paste is then used to further remove residual stress and these small scratches, further eliminating stress on the surface. The remaining surfaces, namely the cylindrical side and the other bottom surface, are polished smooth using 60# sandpaper.

[0030] Furthermore, in step three, the mechanical polishing uses water-soluble diamond polishing paste to remove sandpaper particles and eliminate fine scratches, thereby further reducing residual stress on the surface.

[0031] Furthermore, in step three, the mechanical polishing uses a rotation speed of 1500 rpm and a polishing time of 20 to 30 minutes. This parameter combination can achieve a balance between polishing efficiency and surface quality. That is, the 1500 rpm rotation speed provides a suitable linear velocity to quickly eliminate scratches; the 20 to 30 minute time window matches the rotation speed. Too short a time will result in scratch residue, while too long a time will easily cause uneven surface gloss and edge chamfering.

[0032] Furthermore, in step four, the volume percentage of methanol solution in the electrolytic polishing solution is 80-95%, and the volume percentage of concentrated sulfuric acid solution is 5-20%. The purpose of using this ratio range is twofold: the 5-20% concentrated sulfuric acid provides adequate chemical etching, and its low volume fraction effectively controls the corrosion rate, preventing over-etching of the surface; the 80-95% methanol acts as a solvent, serving a dual purpose: firstly, it adjusts the pH of the electrolyte to stabilize the corrosion process; secondly, its high volatility carries away the heat generated by the electrolytic reaction, avoiding over-etching caused by localized temperature rises.

[0033] Furthermore, in step five, the EBSD resolution surface of the AlMoNbTiV refractory high-entropy alloy sample is directly opposite the negative electrode stainless steel sheet or other steel sheet, thereby forming an electric field path between the steel sheet, the electrolytic polishing solution and the resolution surface of the sample, realizing controllable corrosion of the resolution surface, thereby completely eliminating residual stress and ensuring the uniformity of corrosion.

[0034] Furthermore, in step five, the temperature of the electrolytic polishing solution is room temperature (20–25°C), the polishing voltage is 10–20V, the polishing current is 5A, and the polishing time is 2–4s. The purpose of using these parameter ranges is as follows: room temperature operation eliminates the need for special temperature control equipment, making operation convenient and ensuring stable electrolyte performance; the 10–20V voltage provides a suitable driving force for the electrochemical reaction; too low a voltage will fail to completely remove the stress layer on the analytical surface, while too high a voltage will cause an overly vigorous reaction, easily leading to localized over-corrosion of the analytical surface; the constant 5A current is coordinated with the voltage and time parameters to ensure a moderate charge transfer rate; the short polishing window of 2–4s, matched with the voltage and current parameters, can efficiently remove the residual stress layer while avoiding excessive corrosion, achieving rapid sample preparation.

[0035] Furthermore, in step six, the method for determining whether the AlMoNbTiV refractory high-entropy alloy sample has completed electropolishing is as follows: by visual observation, when more than 95% of the light gray skin on the surface peels off within 2 to 4 seconds, revealing a uniform metallic color and exhibiting a mirror-like reflective effect, the polishing is considered complete. The mirror-like reflective effect serves as the main basis for determining whether the polishing is complete.

[0036] Furthermore, in step six, the cleaning and drying process involves rinsing with clean water and ultrasonically cleaning the analytical surface of the sample with anhydrous ethanol, and then using a hairdryer to blow hot air along either side of the sample, i.e., one side, to dry the surface of the AlMoNbTiV refractory high-entropy alloy sample.

[0037] As a disclosed embodiment of the present invention, the present invention also provides an EBSD sample of an AlMoNbTiV refractory high-entropy alloy. The EBSD sample is obtained using the aforementioned preparation method. The original calibration rate of the EBSD sample reaches over 95%, and the surface is free of residual stress layers and scratches. It can accurately reflect information such as the phase composition, grain size, and grain boundary characteristics of the AlMoNbTiV refractory high-entropy alloy. Specific embodiments are described below for illustration: Example 1 This embodiment includes the following steps: S1. A cylindrical AlMoNbTiV-based as-cast refractory high-entropy alloy sample with a diameter × height of Φ10mm × 15mm was cut using an electrical discharge wire cutting device. S2, the 10mm diameter observation surface of the AlMoNbTiV system as-cast refractory high-entropy alloy sample to be prepared in S1 was ground with 60#, 240#, 400#, 800#, 1000# and 2000# sandpaper respectively until scratches in a uniform direction were visible to the naked eye. The remaining surfaces were ground smooth with 60# sandpaper. S3. The ground AlMoNbTiV-based as-cast refractory high-entropy alloy was mechanically polished using water-soluble diamond polishing paste. Wearing rubber gloves, a fine-fiber polishing cloth was used. The polishing disc speed was 1500 rpm, and the polishing time was 20 minutes. The sample surface was visually inspected intermittently. If scratches remained, mechanical polishing was repeated for 5 minutes until the sample surface was smooth and light gray. The polishing was then stopped. The sample surface was rinsed with water, dehydrated with anhydrous ethanol, and then dried with a hairdryer. S4, the volume ratio of the electrolytic polishing solution used for sample surface treatment is: 80-95% methanol solution and 5-20% concentrated sulfuric acid solution, with the sum of the volume percentages of the two solutions being 100%; Specifically, in this Example 1, the volume ratio of the electrolytic polishing solution is: 92% methanol solution and 8% concentrated sulfuric acid solution.

[0038] S5, using an AlMoNbTiV-based as-cast refractory high-entropy alloy sample as the anode, connected to the positive terminal of a power supply; and using a stainless steel sheet or other steel sheet as the cathode, connected to the negative terminal of a power supply, which is a constant current and regulated power supply. After the voltage stabilizes, the AlMoNbTiV-based as-cast refractory high-entropy alloy sample is immersed in an electrolytic polishing solution. The room temperature of the electrolytic polishing solution is 20-25°C, specifically 25°C in Example 1. The polishing voltage is 15V, and the polishing current is 5A. During the electrolytic polishing process, the EBSD resolution surface faces the negative electrode stainless steel sheet or other steel sheet, and the polishing time is 2-4 seconds. In Example 1, the sample is removed after approximately 2 seconds of polishing. Specifically, the completion of electrolytic polishing is defined as the removal of most of the light gray outer layer from the surface of the EBSD resolution area.

[0039] S6. After electrolytic polishing, the AlMoNbTiV system cast refractory high entropy alloy sample was quickly rinsed with water and ultrasonically cleaned with anhydrous ethanol. Finally, the surface was dried by blowing hot air along one side with a hair dryer. The dried sample surface had no water stains, thus preparing a smooth and clean EBSD sample.

[0040] EBSD testing was performed on the analytical plane of the AlMoNbTiV as-cast refractory high-entropy alloy sample prepared in this embodiment, with a detection step size of 1 μm. The resulting grain orientation distribution diagram is shown below. Figure 2 As shown, from Figure 2It can be seen that the EBSD orientation information of the sample's analytical surface is complete, and the original calibration rate reaches 97.89%.

[0041] Example 2 This embodiment includes the following steps: S1. A cylindrical AlMoNbTiV-based hot isostatic pressing refractory high entropy alloy sample with a diameter × height of Φ10mm × 10mm was cut using an electric discharge wire cutting device. S2, the 10mm diameter surface of the AlMoNbTiV hot isostatic pressing refractory high entropy alloy sample to be prepared in S1 was ground with 60#, 240#, 400#, 800#, 1000# and 2000# sandpaper respectively until scratches in a uniform direction were visible to the naked eye. The remaining surfaces were ground smooth with 60# sandpaper. S3. The ground AlMoNbTiV-based hot isostatic pressing refractory high-entropy alloy was mechanically polished using water-soluble diamond polishing paste. Rubber gloves were worn, and a fine velvet polishing cloth was used. The polishing disc rotated at 1500 rpm for 30 minutes. The sample surface was visually inspected intermittently. If scratches remained, mechanical polishing was repeated for 5 minutes until the sample surface was smooth and light gray. The sample was then rinsed with water, dehydrated with anhydrous ethanol, and dried with a hairdryer. S4, the volume ratio of the electrolytic polishing solution used for sample surface treatment is: 80-95% methanol solution and 5-20% concentrated sulfuric acid solution, with the sum of the volume percentages of the two solutions being 100%; Specifically, in this Example 2, the volume ratio of the electrolytic polishing solution is: 90% methanol solution and 10% concentrated sulfuric acid solution.

[0042] S5, using an AlMoNbTiV-based hot isostatic pressing (HIP) refractory high-entropy alloy sample as the anode, connected to the positive terminal of a power supply; and using a stainless steel sheet or other steel sheet as the cathode, connected to the negative terminal of a power supply, which is a constant current and regulated power supply. After the voltage stabilizes, the AlMoNbTiV-based HIP refractory high-entropy alloy sample is immersed in an electrolytic polishing solution. The temperature of the electrolytic polishing solution is 20–25°C, specifically 20°C in Example 2. The polishing voltage is 20V, and the polishing current is 5A. During the polishing process, the EBSD resolution surface faces the negative electrode stainless steel sheet or other steel sheet, and the polishing time is 2–4 seconds. In Example 2, the sample is removed after approximately 4 seconds of electrolytic polishing. Specifically, the completion of electrolytic polishing is defined as the removal of most of the light gray outer layer from the surface of the EBSD resolution area.

[0043] S6. After electrolytic polishing, the AlMoNbTiV system hot isostatic pressing refractory high entropy alloy sample was quickly rinsed with water and ultrasonically cleaned with anhydrous ethanol. Finally, the surface was dried by blowing hot air along one side with a hair dryer. The dried sample surface had no water stains, thus preparing a smooth and clean EBSD sample.

[0044] EBSD testing was performed on the analytical surface of the AlMoNbTiV-based hot isostatic pressed refractory high-entropy alloy sample prepared in this embodiment, with a detection step size of 1 μm. The resulting grain orientation distribution diagram is shown below. Figure 3 As shown, from Figure 3 It can be seen that the EBSD orientation information of the sample's analytical surface is complete, and the original calibration rate reaches 99.13%.

[0045] In this Example 2, compared with the AlMoNbTiV system cast refractory high-entropy alloy of Example 1, the residual stress inside the alloy sample after hot isostatic pressing is increased. Therefore, it is necessary to increase the electropolishing voltage and extend the electropolishing time to ensure that the residual stress layer on the sample surface is completely removed and the Kikuchi pattern on the analytical surface is accurately calibrated.

[0046] Example 3 This embodiment differs from Embodiment 1 only in that the voltage parameters during electropolishing are changed. The calibration rate of the analytical surface of the AlMoNbTiV as-cast refractory high-entropy alloy sample is analyzed using the electropolishing solution described in this embodiment. The results are shown in Table 1.

[0047] Table 1. Calibration rate at different voltages Electropolishing voltage (V) 10 15 20 Calibration rate (%) 97.38 97.89 97.00 As shown in Table 1, when the electropolishing voltage is in the range of 10-20V, the original calibration rate of the analytical surface of the AlMoNbTiV as-cast refractory high-entropy alloy samples all reached over 95%, indicating that the voltage range selected in this invention is reasonable. Electropolishing of AlMoNbTiV as-cast refractory high-entropy alloy samples at lower and higher voltage parameters, with parameters set to 5V and 25V as comparative examples, showed that the original calibration rates of the analytical surface reached 83.69% and 94.27%, respectively, both below the 95% target. This indicates that, with the electropolishing solution composition remaining constant, increasing or decreasing the polishing voltage is detrimental to the electropolishing of the analytical surface of AlMoNbTiV as-cast refractory high-entropy alloy samples. Especially at a polishing voltage of 5V, the original calibration rate drops significantly, and the orientation information of the analytical surface is severely lacking. EBSD testing with a detection step size of 1 μm yielded the grain orientation distribution map of the AlMoNbTiV-based cast refractory high-entropy alloy sample under a polishing voltage of 5 V, as shown below. Figure 4 As shown.

[0048] Example 4 This embodiment differs from Embodiment 2 only in the formulation of the electropolishing solution. The calibration rate of the analytical surface of the AlMoNbTiV system hot isostatic pressing refractory high entropy alloy sample was analyzed using the electropolishing solution described in this embodiment. The results are shown in Table 2.

[0049] Table 2. Calibration rates under different formulation ratios Methanol (%) Concentrated sulfuric acid (%) Calibration rate (%) 95 5 98.18 90 10 99.13 85 15 97.82 80 20 96.79 As shown in Table 2, different electropolishing solution ratios resulted in varying electropolishing effects on AlMoNbTiV-based hot isostatic pressing refractory high-entropy alloy samples. However, both methanol solutions in the 80–95% range and concentrated sulfuric acid solutions in the 5–20% range ensured an original calibration rate of over 95%, indicating that the electropolishing solution ratios selected in this invention were reasonable. The 90% methanol and 10% concentrated sulfuric acid ratio resulted in the highest original calibration rate of 99.13% for the analytical surface, achieving accurate characterization of grain orientation. Further increasing the concentrated sulfuric acid volume fraction to 25% resulted in a methanol volume fraction of 75%. Using this as a comparative example, the original calibration rate for the analytical surface was 94.36%, lower than the 95% target. This is because when the concentrated sulfuric acid volume fraction exceeded 20%, the corrosiveness of the electropolishing solution increased, leading to a certain degree of over-corrosion of the analytical surface and deteriorating the EBSD calibration effect.

[0050] Comparative Example 5 This comparative example, based on Example 2, replaces the electropolishing solution with a mixture of 6% perchloric acid, 59% methanol, and 35% n-butanol commonly used in titanium alloys or stainless steel, to verify the superiority of the methanol-concentrated sulfuric acid system described in this invention. Figure 5 As shown, the calibration rate of the analytical surface of the AlMoNbTiV system hot isostatic pressing refractory high entropy alloy sample is only 58.70%, and the EBSD calibration effect is significantly lower than that of Example 2 of the present invention.

[0051] The foregoing description illustrates and describes several preferred embodiments of the present invention. However, as previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. An EBSD sample preparation method of an AlMoNbTiV refractory high-entropy alloy, characterized by, The method comprises the following steps: S1. obtaining an AlMoNbTiV refractory high-entropy alloy sample to be prepared; S2. grinding and mechanically polishing the sample to be prepared, and cleaning and drying the sample to be prepared for use; S3. preparing an electrolytic polishing solution composed of a methanol solution and a concentrated sulfuric acid solution; S4. connecting the sample to be prepared, which is dried for use, to the positive pole of a power supply as an anode, and connecting a steel sheet to the negative pole of the power supply as a cathode, and immersing the sample to be prepared in the electrolytic polishing solution for electrolytic polishing; S5. cleaning and drying the sample to be prepared after electrolytic polishing to obtain an EBSD sample of the AlMoNbTiV refractory high-entropy alloy.

2. The EBSD sample preparation method of an AlMoNbTiV-based refractory high-entropy alloy according to claim 1, characterized by, In S1, the AlMoNbTiV refractory high-entropy alloy sample to be prepared is obtained by using an electric spark wire cutting device, the sample to be prepared is a cylinder, the upper surface thereof is used as an observation surface, the diameter of the cylinder is less than 15 mm, and the height of the cylinder is 10-15 mm.

3. The method of claim 1, wherein the AlMoNbTiV refractory high-entropy alloy is characterized by, In S2, the observation surface of the sample to be prepared is ground with 60#, 240#, 400#, 800#, 1000# and 2000# sandpaper in sequence until scratches in a uniform direction are observed by naked eye, and the remaining surface is ground flat with 60# sandpaper.

4. The method of claim 1, wherein the AlMoNbTiV refractory high-entropy alloy is characterized by, In S2, the mechanical polishing is performed by using water-soluble diamond polishing paste at a rotation speed of 1500 rpm for 20-30 minutes.

5. The method of claim 1, wherein the AlMoNbTiV refractory high-entropy alloy is characterized by, In S3, the volume percentage of the methanol solution in the electrolytic polishing solution is 80-95%, and the volume percentage of the concentrated sulfuric acid solution is 5-20%.

6. The method of preparing an EBSD sample of an AlMoNbTiV-based refractory high-entropy alloy according to claim 1, characterized in that, The steel sheet is a stainless steel sheet or other steel sheet.

7. The method of claim 1, wherein the AlMoNbTiV refractory high-entropy alloy is characterized by, In S4, the temperature of the electrolytic polishing solution is room temperature 20-25℃, the polishing voltage is 10-20V, the polishing current is 5A, and the polishing time is 2-4s.

8. The method of claim 1, wherein the AlMoNbTiV refractory high-entropy alloy is characterized by, In S4, the judgment condition for completing electrolytic polishing of the sample to be prepared is that the light gray skin of the analysis surface is peeled off.

9. The method of claim 1, wherein the AlMoNbTiV refractory high-entropy alloy is characterized by, In S5, the sample to be prepared after electrolytic polishing is cleaned and dried by using clean water to rinse and anhydrous ethanol to ultrasonically clean the surface of the alloy sample, and then the surface of the AlMoNbTiV refractory high-entropy alloy sample is blown dry along one side by using a hair dryer.

10. An EBSD sample of an AlMoNbTiV refractory high-entropy alloy, characterized in that, The EBSD sample is obtained by using the preparation method of any one of claims 1-9.

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