Method for preparing EBSD sample of double-phase titanium alloy at normal temperature

Abstract

The invention discloses a double-phase titanium alloy normal-temperature EBSD sample preparation method which comprises the following steps: S1, obtaining a titanium alloy sample, and grinding and cleaning a to-be-polished surface of the titanium alloy sample by using abrasive paper to obtain an EBSD sample ground by using the abrasive paper; and S2, the EBSD sample polished by the abrasive paper serves as a positive electrode, a stainless steel sheet serves as a negative electrode, the polished surface of the EBSD sample polished by the abrasive paper is subjected to electrolytic polishing in a normal-temperature electrolytic polishing solution, ultrasonic cleaning is conducted after electrolytic polishing is finished, and the EBSD sample is obtained after blow-drying. According to the preparation method of the EBSD sample, the preparation process is simplified, the electrolytic polishing time is shortened, the calibration rate of the EBSD sample is effectively improved, and the safety is higher.

Description

Technical Field

[0001] The invention relates to the technical field of titanium alloy surface treatment, and in particular to a method for preparing an EBSD sample of a dual-phase titanium alloy at room temperature. Background Art

[0002] Titanium alloys have high specific strength, good corrosion resistance, high heat resistance, and good biocompatibility. They have many excellent properties that are difficult to achieve with other metals and are widely used in many important fields. EBSD technology (electron backscatter diffraction technology) is a technology based on scanning electron microscopy. When the electron beam scans on a polycrystalline sample in a grid form, the orientation of the crystal at each point of the polycrystalline sample can be measured. The surface distribution map obtained can reveal the morphology, orientation, and large and small angle grain boundaries, texture and other microscopic characteristics of the grains; it is widely used in aviation, aerospace, medicine, military industry, sports and leisure and other fields. EBSD detection is often used in the study and analysis of the microscopic characteristics of titanium alloys; the surface of the sample used for EBSD detection must be kept flat and clean, have good conductivity, and be free of oxide layer and stress layer.

[0003] Traditional methods for preparing EBSD samples have various limitations, such as ion polishing technology, which has high preparation costs and high equipment requirements; low-temperature electrolytic polishing technology, which has high requirements for low-temperature environment, complex electrolyte ratio, high requirements for sample surface finish, and safety hazards in the preparation process; vibration polishing technology, which has high requirements for sample surface finish, high equipment requirements, and is time-consuming; the existing electrolytic polishing technology for preparing duplex titanium alloy EBSD samples has a complex electrolyte composition ratio, and the electrolyte needs to be low-temperature cooled, the preparation process is cumbersome, and the cost is high; the existing electrolytic polishing technology for preparing duplex titanium alloy EBSD samples requires complex pretreatment, and mechanical polishing is required after polishing with different brands of sandpaper in sequence. The mechanical polishing time is long, and the cost of polishing liquid and polishing cloth is high. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for preparing an EBSD sample of a duplex titanium alloy at room temperature.

[0005] The technical solution of the present invention is: a method for preparing an EBSD sample of a dual-phase titanium alloy at room temperature, comprising the following steps:

[0006] S1. Obtain a titanium alloy sample, and sandpaper polish and clean the surface to be polished of the titanium alloy sample to obtain an EBSD sample after sandpaper polishing;

[0007] S2, using the sandpaper-polished EBSD sample as an anode and the stainless steel sheet as a cathode, electrolytically polishing the polished surface of the sandpaper-polished EBSD sample in an electrolytic polishing solution at room temperature, and ultrasonically cleaning and drying the EBSD sample after the electrolytic polishing to obtain the EBSD sample;

[0008] Among them, the DC power supply voltage of electrolytic polishing is 15-25V, the current of electrolytic polishing is 0.2-0.3A, and the time of electrolytic polishing is 90-120s.

[0009] Description: At present, the commonly used surface treatment methods for the preparation of titanium alloy specimens are mechanical polishing and electrolytic polishing; but mechanical polishing can easily damage the surface of the specimen and leave a residual stress layer, resulting in poor calibration rate; and electrolytic polishing requires a special polishing liquid at low temperature. Moreover, the selection of electrolytic polishing parameters is very sensitive to the different materials of duplex titanium alloys. If the temperature, voltage, current, and polishing time during electrolytic polishing are not properly selected, the polishing quality of the titanium alloy specimen surface will be affected. Therefore, when preparing titanium alloy specimens in various states, the electrolytic polishing parameters need to be debugged multiple times, which is not only cumbersome to operate, but also consumes additional titanium alloy materials.

[0010] The present invention improves the electrolytic polishing technology and can prepare EBSD samples at room temperature using a simple electrolytic polishing solution. There is no need to mechanically polish the titanium alloy sample, which greatly simplifies the preparation process, shortens the electrolytic polishing time, and reduces the equipment and environmental requirements for preparing EBSD samples, thereby lowering the manufacturing cost.

[0011] Furthermore, the sandpaper polishing method is: use silicon carbide sandpapers of models 80#, 400#, 800#, 1000#, and 2000# to polish the surface to be polished of the titanium alloy sample in sequence, and rotate the titanium alloy sample 90° before replacing the silicon carbide sandpaper each time to facilitate grinding away the previous scratches. After sandpaper polishing, clean it with ethanol solution to obtain an EBSD sample after sandpaper polishing.

[0012] Note: Sandpaper grinding generally includes initial rough grinding, intermediate grinding, and fine grinding, usually starting from 80 mesh. Low-mesh silicon carbide sandpaper can quickly remove the surface material of the titanium alloy specimen and smooth the surface. At the same time, the silicon carbide sandpaper should be kept parallel to the surface of the titanium alloy specimen and polished with uniform force to avoid excessive polishing in a certain area.

[0013] Intermediate grinding with 400 mesh can further refine the surface. The transition from low mesh to high mesh should be gradual to avoid excessive jumps that lead to uneven surface. After intermediate grinding, fine grinding with 800 mesh, 1000 mesh, and 2000 mesh is used to make the polished surface of the titanium alloy sample smoother. At the same time, a softer force should be used in the fine grinding stage to avoid damaging the smooth surface that has been formed.

[0014] Furthermore, the electrolytic polishing is carried out in a glass container, by placing one end of the stainless steel sheet into the bottom of the glass container, and connecting the other end of the stainless steel sheet to the negative electrode of a DC power supply; using a metal clamp with a wire to immerse the polished surface of the EBSD sample after sandpaper polishing into the electrolytic polishing liquid, and the other end of the metal clamp is connected to the positive electrode of the DC power supply.

[0015] Description: When the current passes through, the metal atoms on the surface of the workpiece will lose electrons to become cations and enter the electrolyte. This process is called anodic dissolution. Since the current density is higher on the raised parts of the polished surface of the EBSD sample after sandpaper polishing, these parts will be dissolved first, thereby gradually making the surface smooth. As the anodic dissolution proceeds, the tiny raised parts on the surface of the workpiece will gradually be dissolved, while the depressed parts will be relatively retained, making the entire polished surface smooth. This process not only removes burrs, scratches and other defects on the polished surface, but also improves the smoothness and brightness of the polished surface. Using a stainless steel sheet as the cathode and the EBSD sample after sandpaper polishing as the anode can effectively electropolish the polished surface, thereby obtaining an EBSD sample after electropolishing.

[0016] Furthermore, the electrolytic polishing solution is 4-7% perchloric acid and the remainder is an anhydrous ethanol solution, measured by volume percentage.

[0017] Description: The selection of electrolytic polishing liquid is very critical. It is not only conductive, but also can form a thin film during the electrolysis process to control the dissolution rate of the metal and ensure the uniformity of the polishing effect. The electrolytic polishing liquid prepared in the above ratio is used in conjunction with the electrolytic polishing process of the present invention. EBSD samples can be prepared at room temperature without the need for low temperature.

[0018] Furthermore, during the electrolytic polishing, the polished surface of the EBSD sample after sandpaper polishing is shaken, and the polished surface of the EBSD sample after sandpaper polishing is always immersed in the electrolytic polishing liquid.

[0019] Note: Since the use of electrolytic polishing liquid is indispensable in electrolytic polishing, the film formed on the polishing surface is inevitable. The shaking treatment can control the destruction of the film and disturb the electrolytic polishing liquid, so that the polishing surface can be polished more evenly during electrolytic polishing, and an EBSD sample with a high calibration rate can be obtained.

[0020] Furthermore, the shaking treatment is to shake the EBSD sample after sandpaper polishing in an electrolytic polishing solution according to a shaking amplitude L and a shaking period of 10 to 20 seconds per time; wherein the shaking amplitude L is the distance from one end point X1 to the other end point X2 of the shaking treatment, and L is 20 to 30 cm.

[0021] Note: Through experiments, we found that when short-amplitude and high-frequency shaking / vibration was performed, the calibration rate of the prepared EBSD sample decreased. This may be because when short-amplitude and high-frequency shaking / vibration was performed, the film formed during the electrolysis process of the polished surface was excessively damaged, so that the film lost its function of protecting the titanium alloy surface from excessive corrosion. Therefore, when short-amplitude and high-frequency shaking / vibration was performed, the calibration rate of the prepared EBSD sample decreased.

[0022] When using long-amplitude and low-frequency shaking, the film can be properly controlled and destroyed, promoting the preferential dissolution of the higher raised parts of the polished surface, making the polished surface smoother, and improving the uniformity of the polishing effect, thereby effectively removing burrs, scratches and other defects on the polished surface, and improving the smoothness and brightness of the polished surface.

[0023] Furthermore, the current of the electrolytic polishing is adjusted according to the distance L0 between the EBSD sample and X1 or X2 after sandpaper polishing. Specifically,

[0024] When >L0, the current of electrolytic polishing is 0.27~0.3A; when ≤L0, the current of electrolytic polishing drops from 0.27~0.3A to 0.2~0.23A; L0 is 0~5cm.

[0025] Note: On the basis of shaking treatment, the current of electropolishing is dynamically adjusted according to the change of speed when the polishing surface shakes. During shaking treatment, when the polishing surface moves to one end point X1 or the other end point X2, its speed drops to 0, that is, the relative speed between the polishing surface and the electropolishing liquid is 0 at this time. At this time, reducing the current of electropolishing can further avoid excessive corrosion. Considering the problem of slowing down to reach end point X1 or X2, the current of electropolishing is reduced within 5 cm, which can better achieve the effect of shaking treatment and obtain EBSD samples with higher calibration rate.

[0026] The beneficial effects of the present invention are:

[0027] (1) The EBSD sample preparation method of the present invention simplifies the preparation process, does not require mechanical polishing, and can be prepared at room temperature, shortening the electrolytic polishing time and effectively improving the calibration rate of the EBSD sample.

[0028] (2) The EBSD sample preparation method of the present invention can reduce the equipment and environmental requirements for preparing EBSD samples, and has a lower preparation cost. The working current and voltage during electrolysis are relatively low, and the safety is higher. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1The dual-phase titanium alloy Ti-B12 (Ti-10Mo-6Zr-4Sn-3Nb) prepared by the preparation method of the present invention is subjected to EBSD macroscopic examination after electrolytic polishing. Figure 1 .

[0030] Figure 2 The dual-phase titanium alloy Ti-B12 (Ti-10Mo-6Zr-4Sn-3Nb) prepared by the preparation method of the present invention is subjected to EBSD macroscopic examination after electrolytic polishing. Figure 2 . DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with specific implementation methods to better reflect the advantages of the present invention.

[0032] Example 1: A method for preparing an EBSD sample of a dual-phase titanium alloy at room temperature, comprising the following steps:

[0033] S1. Obtain a titanium alloy sample, and sandpaper polish and clean the surface to be polished of the titanium alloy sample to obtain an EBSD sample after sandpaper polishing;

[0034] The sandpaper polishing method is as follows: the surface to be polished of the titanium alloy sample is polished using silicon carbide sandpapers of models 80#, 400#, 800#, 1000#, and 2000# in sequence, and the titanium alloy sample is rotated 90° before each replacement of the silicon carbide sandpaper to facilitate the removal of scratches caused by the previous model of silicon carbide sandpaper. After the sandpaper polishing is completed, it is cleaned with an ethanol solution to obtain an EBSD sample after sandpaper polishing;

[0035] S2. Place one end of a stainless steel sheet at the bottom of a glass container containing an electrolytic polishing solution, and connect the other end of the stainless steel sheet to the negative electrode of a DC power supply; immerse the polished surface of the EBSD sample after sandpaper polishing into the electrolytic polishing solution using a metal clamp with a wire, and connect the other end of the metal clamp to the positive electrode of a DC power supply. Electropolish the polished surface of the EBSD sample after sandpaper polishing in the electrolytic polishing solution at room temperature, and ultrasonically clean and blow dry the EBSD sample after the electrolytic polishing. It is understood that ultrasonic cleaning is to rinse the EBSD sample in anhydrous ethanol, clean it with ultrasound, and then blow dry the EBSD sample with a hair dryer;

[0036] The DC power supply voltage of the electropolishing is 20V, the current of the electropolishing is 0.28A, the time of the electropolishing is 110s, and the electropolishing solution is 5% perchloric acid and 95% anhydrous ethanol solution.

[0037] Experimental Example: The EBSD sample of the above-mentioned Example 1 was measured using the EBSD (electron backscatter diffraction) detection method, and the specific steps are as follows:

[0038] 1) Start the equipment: Start the scanning electron microscope (SEM), EBSD control computer and EBSD image processor and stabilize them for 30 minutes;

[0039] 2) Install the sample: Load the EBSD sample into the SEM, making sure that the EBSD sample coordinate system coincides with the electron microscope coordinate system; adjust the position of the EBSD sample so that its edge is parallel or perpendicular to the tensile direction or rolling direction, and use the cross alignment lines on the electron microscope for calibration;

[0040] 3) Sample tilt: Tilt the EBSD sample 70° so that the EBSD sample faces the EBSD probe. If a tilted sample stage is used, this step can be omitted. Then perform tilt correction and dynamic focusing, and adjust the working distance to 20 mm.

[0041] 4) Generate Kikuchi pattern: Insert the EBSD probe and generate Kikuchi pattern in point mode. If clear Kikuchi bands can be seen at this time, it means that the measurement conditions are basically suitable.

[0042] 5) Optimize the image: Return to the SEM image analysis mode, optimize the scanning speed to obtain the best image quality, perform the back-buckling of the Kikuchi pattern on the EBSD system computer, and adjust the brightness, contrast and other parameters to optimize the Kikuchi band effect;

[0043] 6) Data acquisition: Start the EBSD data acquisition software, create a file name for storing data, and call in the crystallographic library file for reference comparison and the calibration file for the probe orientation, select several Kikuchi patterns for automatic calibration, check the reliability and error size of the calibration, and calibrate the working distance, determine the parameters for orientation imaging measurement, such as step size, number of measurement points in the X / Y direction, magnification, etc., and start the automatic button;

[0044] 7) Orientation imaging: After orientation imaging is completed, take a topographic image of the measurement area, and use EBSD software to process and analyze the collected data to obtain Figure 1 , Figure 2 The EBSD macroscopic image of the dual-phase titanium alloy Ti-B12 (Ti-10Mo-6Zr-4Sn-3Nb) after electrolytic polishing was detected, and the total calibration rate of the dual phase was calculated. The results are shown in Table 1 below:

[0045] Table 1 Total calibration rate of two phases of EBSD samples

[0046] Group Biphase total calibration rate / % Example 1 98.68

[0047] It can be seen from Table 1 that the preparation of EBSD samples by this method can improve the calibration rate of EBSD samples measured by the EBSD detection method. At the same time, a control is set. The control is based on Example 1, and mechanical polishing is performed after sandpaper polishing. A polishing machine is used with a speed of 300r / min until a bright mirror surface is thrown out, and then electrolytic polishing is performed; EBSD detection is performed on the EBSD sample prepared by the control, and the total calibration rate of the two phases is calculated. The results are shown in Table 2 below:

[0048] Table 2 Total calibration rate of two phases of EBSD samples

[0049] Group Biphase total calibration rate / % Comparison 98.75

[0050] It can be seen from Table 2 that adding mechanical polishing to the present method can further improve the total calibration rate of the two-phase, but the improvement in the calibration rate is not obvious. It can be seen that the present method can be used to prepare EBSD samples that can measure a high calibration rate without using mechanical polishing.

[0051] Example 2: This example is different from Example 1 in that the DC power supply voltage of the electrolytic polishing is 15V, and the current of the electrolytic polishing is 0.2A.

[0052] Example 3: This example is different from Example 1 in that the DC power supply voltage of the electrolytic polishing is 25V, and the current of the electrolytic polishing is 0.3A.

[0053] Example 4: This example is different from Example 1 in that the electrolytic polishing time is 90 seconds.

[0054] Example 5: This example is different from Example 1 in that the electrolytic polishing time is 120 s.

[0055] Example 6: This example is different from Example 1 in that the electrolytic polishing solution is 4% perchloric acid and 96% anhydrous ethanol solution.

[0056] Example 7: This example is different from Example 1 in that the electrolytic polishing solution is 7% perchloric acid and 93% anhydrous ethanol solution.

[0057] In order to explore the influence of various process parameters of electrolytic polishing on the preparation of EBSD samples in the present invention, EBSD detection is performed on the EBSD samples prepared in the above embodiments, and the total calibration rate of the two-phase is calculated. The results are shown in Table 3 below:

[0058] Table 3 Total calibration rate of two phases of EBSD samples

[0059] Group Biphase total calibration rate / % Example 2 98.34 Example 3 98.61 Example 4 98.44 Example 5 98.60 Example 6 98.65 Example 7 98.53

[0060] It can be seen from Table 3 that after using different electrolytic polishing process parameters and different ratios of electrolytic polishing liquid, the calibration rates of the EBSD samples obtained after EBSD detection are different. The specific analysis is as follows:

[0061] 1) After using different DC power supply voltages and currents for electrolytic polishing, the prepared EBSD sample has a certain impact. By comparing Example 2 and Example 3 with Example 1, after increasing or decreasing the voltage and current on the basis of Example 1, the total calibration rate of the two-phase EBSD sample is reduced. It can be seen that improper selection of voltage and current during electrolytic polishing will affect the polishing quality of the titanium alloy sample surface. Therefore, the current and voltage parameters of Example 1 are relatively better in the preparation of EBSD samples.

[0062] 2) After using different electrolytic polishing times, there is a certain impact on the prepared EBSD sample. By comparing Example 4, Example 5 and Example 1, the total duplex calibration rate of the EBSD sample is reduced by increasing or decreasing the electrolytic polishing time on the basis of Example 1. Insufficient electrolytic polishing time will result in insufficient polishing surface finish, while too long electrolytic polishing time may cause excessive corrosion. It can be seen that improper selection of electrolytic polishing time during electrolytic polishing will affect the polishing quality of the titanium alloy sample surface. Therefore, the current and voltage parameters of Example 1 are relatively superior in the preparation of EBSD samples.

[0063] 3) After using electrolytic polishing liquid with different ratios, it has a certain impact on the prepared EBSD sample. By comparing Example 6, Example 7 and Example 1, the total calibration rate of the two-phase of the EBSD sample is reduced when electrolytic polishing is performed using electrolytic polishing liquid with different perchloric acid contents. The reduction of the perchloric acid content may cause insufficient electrolytic polishing under the rated electrolytic polishing time, resulting in insufficient polishing surface finish. The increase of the perchloric acid content may cause excessive corrosion to the polishing surface under the rated electrolytic polishing time. It can be seen that electrolytic polishing liquid with different ratios will affect the polishing quality of the titanium alloy sample surface. Therefore, it is relatively better to use the electrolytic polishing liquid of Example 1 to prepare the EBSD sample.

[0064] Example 8: The difference between this example and Example 1 is that, during the electrolytic polishing, the polished surface of the EBSD sample after sandpaper polishing is shaken, and the polished surface of the EBSD sample after sandpaper polishing is always immersed in the electrolytic polishing liquid. The shaking treatment is to shake the EBSD sample after sandpaper polishing in the electrolytic polishing liquid with a shaking amplitude L of 25 cm and a shaking period of 16s / time. It can be understood that 16s / time means that the one-way time of the EBSD sample from "X1 to X2" or "X2 to X1" after sandpaper polishing is 16s; wherein, the shaking amplitude L is the distance from one end point X1 to the other end point X2 of the shaking treatment.

[0065] Example 9: This example is different from Example 8 in that shaking is performed in the electrolytic polishing liquid at a shaking amplitude L of 20 cm.

[0066] Example 10: This example is different from Example 8 in that shaking is performed in the electrolytic polishing liquid at a shaking amplitude L of 30 cm.

[0067] Example 11: This example is different from Example 8 in that the shaking is performed in the electrolytic polishing liquid with a shaking cycle of 10 s / time

[0068] Example 12: This example is different from Example 8 in that shaking is performed in the electrolytic polishing liquid at a shaking cycle of 20 s / time.

[0069] Example 13: This example is different from Example 8 in that the current of the electrolytic polishing is adjusted according to the distance L0 between the EBSD sample and X1 or X2 after sandpaper polishing. Specifically,

[0070] When >L0, the electropolishing current is 0.28A; when ≤L0, the electropolishing current is reduced from 0.28A to 0.21A; wherein L0 is 3cm, that is, when the EBSD sample moves to a distance of 3cm between X1 or X2 after sandpaper polishing, the electropolishing current is adjusted, and the current response time of the electropolishing is adjusted to 1s in this application.

[0071] Example 14: This example differs from Example 13 in that, when >L0, the current of electrolytic polishing is 0.27A; when ≤L0, the current of electrolytic polishing is reduced from 0.27A to 0.2A.

[0072] Example 15: This example differs from Example 13 in that, when >L0, the current of electrolytic polishing is 0.3A; when ≤L0, the current of electrolytic polishing is reduced from 0.3A to 0.23A.

[0073] Example 16: This example is different from Example 13 in that L0 is 0 cm. It is understandable that since the distance is 0, regulation requires reaction time. Therefore, when the distance is within 1 cm, the EBSD sample after sandpaper polishing is kept at X1 or X2 for 2 seconds to leave reaction time for the current regulation of electrolytic polishing.

[0074] Example 17: This example is different from Example 13 in that L0 is 5 cm.

[0075] In order to explore the influence of different electrolytic polishing processes on the preparation of EBSD samples in the present invention, EBSD detection is performed on the EBSD samples prepared in the above embodiments, and the total calibration rate of the two-phase is calculated. The results are shown in Table 4 below:

[0076] Table 4 Total calibration rate of two-phase of EBSD samples

[0077] Group Biphase total calibration rate / % Example 8 99.07 Example 9 98.94 Example 10 99.01 Embodiment 11 98.89 Example 12 98.97 Example 13 99.35 Embodiment 14 99.21 Embodiment 15 99.25 Example 16 99.26 Embodiment 17 99.19

[0078] It can be seen from Table 4 that when EBSD samples are prepared using different electrolytic polishing process parameters, the calibration rate of the obtained EBSD samples after EBSD detection is improved to a certain extent compared with the EBSD samples prepared in Example 1. The specific analysis is as follows:

[0079] 1) After the shaking treatment with different shaking amplitudes L, there is a certain influence on the prepared EBSD sample. By comparing Example 9, Example 10 and Example 8, when electrolytic polishing is performed with different shaking amplitudes L, the total two-phase calibration rate of the EBSD sample is reduced. It can be seen that different shaking amplitudes L (i.e., the relative flow rate between the polishing surface and the electrolytic polishing liquid) will affect the polishing quality of the titanium alloy sample surface. Therefore, it is relatively better to use the shaking amplitude L of Example 8 for EBSD sample preparation.

[0080] 2) After shaking treatment with different shaking cycles, the prepared EBSD samples are affected to a certain extent. By comparing Example 11, Example 12 and Example 8, the total two-phase calibration rate of the EBSD samples is reduced when electropolishing is performed with different shaking cycles. It can be seen that different shaking cycles (i.e., the relative flow rate between the polishing surface and the electropolishing liquid) will affect the polishing quality of the titanium alloy sample surface. Therefore, the shaking cycle of Example 8 is relatively better for EBSD sample preparation.

[0081] 3) After shaking treatment with different electropolishing currents, the prepared EBSD samples were affected to a certain extent. By comparing Example 14, Example 15 and Example 13, the total two-phase calibration rate of the EBSD samples decreased when electropolishing was performed with different electropolishing currents. It can be seen that different currents combined with shaking treatment (i.e., the synergistic effect of the relative flow velocity between the polishing surface and the electropolishing liquid and the current size) will affect the polishing quality of the titanium alloy sample surface. Therefore, it is relatively better to use the current size of Example 13 for EBSD sample preparation.

[0082] 4) After the shaking treatment at different distances L0 for adjusting the current, there is a certain influence on the prepared EBSD sample. By comparing Example 16, Example 17 and Example 13, when the current is adjusted at different distances L0, the total calibration rate of the two-phase of the EBSD sample is reduced. It can be seen that the distances of different current regulation (i.e., the time of current regulation and the action time of different currents) will affect the polishing quality of the titanium alloy sample surface. Therefore, it is relatively better to use the distance L0 of Example 13 for EBSD sample preparation.

[0083] At the same time, a control was set up. The control used a short-amplitude high-frequency vibration titanium alloy sample. Specifically, the vibration amplitude was ±3 cm and the reciprocating frequency was 60 times / min. The EBSD sample prepared by the control was subjected to EBSD detection, and the total calibration rate of the two phases was calculated. The results are shown in Table 5 below:

[0084] Table 5 Total calibration rate of two phases of EBSD samples

[0085] Group Biphase total calibration rate / % Comparison 98.33

[0086] It can be seen from Table 5 that the calibration rate of the EBSD sample prepared after using the short-amplitude high-frequency vibration titanium alloy sample has decreased. This may be because during the electrolysis of the polished surface, the short-amplitude high-frequency vibration caused excessive damage to the thin film formed on the polished surface, causing the film to lose the function of protecting the titanium alloy surface from excessive corrosion. It can be seen that the long-amplitude low-frequency shaking treatment of the present invention can well achieve the improvement of the electrolytic polishing effect of the EBSD sample.

Claims

1. A method for preparing EBSD samples of dual-phase titanium alloy at room temperature, characterized in that: The following steps are involved: S1. Obtain a titanium alloy sample, and sandpaper polish and clean the surface to be polished of the titanium alloy sample to obtain an EBSD sample after sandpaper polishing; S2, using the sandpaper-polished EBSD sample as an anode and the stainless steel sheet as a cathode, electrolytically polishing the polished surface of the sandpaper-polished EBSD sample in an electrolytic polishing solution at room temperature, and ultrasonically cleaning and drying the EBSD sample after the electrolytic polishing to obtain the EBSD sample; Among them, the DC power supply voltage of electrolytic polishing is 15-25V, the current of electrolytic polishing is 0.2-0.3A, and the time of electrolytic polishing is 90-120s.

2. The method for preparing an EBSD sample of a dual-phase titanium alloy at room temperature according to claim 1, characterized in that: The sandpaper polishing method is: using silicon carbide sandpapers of models 80#, 400#, 800#, 1000#, and 2000# to polish the surface to be polished of the titanium alloy sample in sequence, and rotating the titanium alloy sample by 90° before replacing the silicon carbide sandpaper each time, and cleaning it with an ethanol solution after sandpaper polishing to obtain an EBSD sample after sandpaper polishing.

3. The method for preparing EBSD samples of a dual-phase titanium alloy at room temperature according to claim 1, characterized in that: The electrolytic polishing is carried out in a glass container, by placing one end of a stainless steel sheet into the bottom of the glass container, and connecting the other end of the stainless steel sheet to the negative electrode of a direct current power supply; using a metal clamp with a wire to immerse the polished surface of the EBSD sample after sandpaper polishing into an electrolytic polishing liquid, and the other end of the metal clamp is connected to the positive electrode of a direct current power supply, and the direct current power supply voltage of the electrolytic polishing is 15 to 25V.

4. The method for preparing an EBSD sample of a dual-phase titanium alloy at room temperature according to claim 1, characterized in that: Calculated by volume percentage, the electrolytic polishing solution is 4-7% perchloric acid and the remainder is anhydrous ethanol solution.

5. The method for preparing EBSD samples of a dual-phase titanium alloy at room temperature according to claim 1, characterized in that: During the electrolytic polishing, the polished surface of the EBSD sample after sandpaper polishing is shaken, and the polished surface of the EBSD sample after sandpaper polishing is always immersed in the electrolytic polishing liquid.

6. A method for preparing EBSD samples of a dual-phase titanium alloy at room temperature as claimed in claim 5, characterized in that: The shaking treatment is to shake the EBSD sample after sandpaper polishing in an electrolytic polishing solution according to a shaking amplitude L and a shaking period of 10 to 20 seconds per time; wherein the shaking amplitude L is the distance from one end point X1 to the other end point X2 of the shaking treatment, and L is 20 to 30 cm.

7. A method for preparing EBSD samples of a dual-phase titanium alloy at room temperature as claimed in claim 6, characterized in that: The current of the electrolytic polishing is adjusted according to the distance L0 between the EBSD sample and X1 or X2 after sandpaper polishing. Specifically, When >L0, the current of electrolytic polishing is 0.27~0.3A; when ≤L0, the current of electrolytic polishing drops from 0.27~0.3A to 0.2~0.23A; L0 is 0~5cm.

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