In-situ ebsd characterization of metal electroplated ultra-thin strips

Abstract

The application discloses a quasi-in-situ EBSD characterization method for electric pulse treatment of metal extremely thin strips and relates to the technical field of microstructure characterization of metal extremely thin strips. The characterization method comprises the following steps: obtaining a metal extremely thin strip sample; sequentially performing primary electric pulse treatment and primary electrolytic polishing treatment on the metal extremely thin strip sample; determining a quasi-in-situ observation area on the metal extremely thin strip sample and performing primary EBSD characterization on the quasi-in-situ observation area; sequentially performing subsequent electric pulse treatment and subsequent electrolytic polishing treatment on the metal extremely thin strip sample; wherein the treatment time of the subsequent electrolytic polishing treatment is shorter than that of the primary electrolytic polishing treatment; performing subsequent EBSD characterization on the quasi-in-situ observation area; and repeating the subsequent electric pulse treatment, the subsequent electrolytic polishing treatment and the subsequent EBSD characterization at least once.

Description

Technical Field

[0001] This invention relates to the field of microstructure characterization technology for ultrathin metal strips, and in particular to a quasi-in-situ EBSD characterization method for ultrathin metal strips subjected to electrical pulse treatment. Background Technology

[0002] Electron backscatter diffraction (EBSD) characterization can obtain microstructure information such as grain morphology, grain orientation, and grain boundary distribution of metallic materials, and therefore can be used to study the effect of electrical pulse treatment on the microstructure of extremely thin metal strips.

[0003] How to use the EBSD characterization method to obtain the true and accurate microstructure of ultrathin metal strips after electrical pulse treatment, and to accurately characterize the changes in the microstructure of the sample as the electrical pulse treatment process progresses, has become an urgent problem to be solved in this field. Summary of the Invention

[0004] The purpose of this invention is to provide a quasi-in-situ EBSD characterization method for electrically pulse-treated ultrathin metal strips, so as to accurately characterize the changes in the microstructure of ultrathin metal strips as the electrical pulse treatment process progresses.

[0005] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a quasi-in-situ EBSD characterization method for electrically pulse-treated extremely thin metal strips, comprising: Obtaining extremely thin metal strip samples; The metal ultrathin strip sample was subjected to initial electrical pulse treatment and initial electrolytic polishing treatment in sequence; A quasi-in-situ observation region was determined on the extremely thin metal strip sample, and the quasi-in-situ observation region was initially characterized by EBSD. The metal ultrathin strip sample is subjected to subsequent electrical pulse treatment and subsequent electrolytic polishing treatment in sequence; wherein the processing time of the subsequent electrolytic polishing treatment is shorter than the processing time of the initial electrolytic polishing treatment; The quasi-in-situ observation area was then characterized by EBSD. The subsequent electrical pulse processing, the subsequent electropolishing processing, and the subsequent EBSD characterization are repeated at least once.

[0006] Optionally, in the above-mentioned quasi-in-situ EBSD characterization method for electro-pulse processed metal ultrathin strips, the temperature of the electro-polishing solution is -20℃ to -10℃, the electro-polishing voltage is 15V to 20V, and the electro-polishing current is 0.4A to 0.6A during the initial electro-polishing process and each subsequent electro-polishing process.

[0007] Optionally, in the above-mentioned quasi-in-situ EBSD characterization method for electro-pulse processed metal ultrathin strips, the processing time of the initial electropolishing treatment is 10s to 30s, and the processing time of each subsequent electropolishing treatment is 1s to 2s.

[0008] Optionally, in the above-described quasi-in-situ EBSD characterization method for electrically pulsed metal ultrathin strips, before the initial electropolishing treatment and each subsequent electropolishing treatment, the characterization method further includes: Liquid nitrogen is added to the electropolishing solution to adjust the temperature of the electropolishing solution to -20℃ to -10℃.

[0009] Optionally, in the above-described quasi-in-situ EBSD characterization method for electrically pulsed metal ultrathin strips, the current, frequency, and duty cycle of each subsequent electrical pulse treatment are the same as those of the initial electrical pulse treatment.

[0010] Optionally, in the above-described quasi-in-situ EBSD characterization method for electrically pulsed metal ultrathin strips, determining the quasi-in-situ observation area includes: The location of the quasi-in-situ observation area is determined based on at least one of the edge contour, surface feature region, and preset positioning region of the ultrathin metal strip sample.

[0011] Optionally, in the above-described quasi-in-situ EBSD characterization method for electrically pulse-processed extremely thin metal strips, after the initial electropolishing treatment and before determining the quasi-in-situ observation area, and after each subsequent electropolishing treatment and before performing the subsequent EBSD characterization, the characterization method further includes: The metal ultrathin strip sample was ultrasonically cleaned with anhydrous ethanol and then dried with inert gas.

[0012] Optionally, in the above-described quasi-in-situ EBSD characterization method for electrically pulse-treated metallic ultrathin strips, obtaining the metallic ultrathin strip sample includes: Based on the clamping distance of the electrical pulse processing device and the size of the observation area required for quasi-in-situ EBSD characterization, wire cutting of the ultra-thin metal strip is performed to obtain the cut metal strip part. The metal ultrathin strip cut part was ultrasonically cleaned in anhydrous ethanol and then dried with cold air to obtain the metal ultrathin strip sample.

[0013] Optionally, in the above-mentioned quasi-in-situ EBSD characterization method for electro-pulse processed metal ultrathin strips, the electro-polishing solution used in the initial electro-polishing treatment and each subsequent electro-polishing treatment is a mixture of perchloric acid and anhydrous ethanol, wherein the volume fraction of perchloric acid in the mixture is 10%~20%.

[0014] Optionally, in the above-described quasi-in-situ EBSD characterization method for electro-pulse processed metal ultrathin strips, the processing time of each subsequent electropolishing treatment is 1 / 30 to 1 / 5 of the processing time of the initial electropolishing treatment.

[0015] Compared with the prior art, the quasi-in-situ EBSD characterization method for electro-pulse treated metal ultrathin strips provided in this application performs electrolytic polishing on the metal ultrathin strip sample after the initial electro-pulse treatment and after each subsequent electro-pulse treatment to remove the oxide layer formed on the sample surface after the electro-pulse treatment, reduce the influence of the oxide layer on the EBSD characterization, and enable the EBSD characterization results obtained at each treatment stage to truly reflect the microstructure state of the metal ultrathin strip at the corresponding treatment stage. Based on this, by making the processing time of subsequent electropolishing treatment shorter than that of the initial electropolishing treatment, the oxide layer formed by subsequent electropulse treatment can be removed while reducing the removal of surface material of the sample by subsequent electropolishing treatment. This avoids significant changes in the observed surface due to excessively long subsequent electropolishing time, and ensures that the observed areas characterized by different treatment stages maintain a good correspondence, thereby improving the accuracy of EBSD characterization results obtained from different treatment stages.

[0016] In summary, by performing initial EBSD characterization on the quasi-in-situ observation area, followed by subsequent EBSD characterization after electrical pulse processing and electropolishing, the microstructure information of the quasi-in-situ observation area at different stages of electrical pulse processing can be obtained. By repeating the subsequent electrical pulse processing, electropolishing, and EBSD characterization at least once, the changes in the microstructure of the quasi-in-situ observation area at different stages of electrical pulse processing can be compared. This allows for a true and accurate characterization of the changes in the microstructure of the ultrathin metal strip as the electrical pulse processing progresses, which helps in analyzing the effect of electrical pulse processing on the microstructure of the ultrathin metal strip and provides a basis for selecting electrical pulse processing parameters. Attached Figure Description

[0017] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic flowchart of a quasi-in-situ EBSD characterization method for electrically pulse-processed extremely thin metal strips provided in an embodiment of the present invention. Detailed Implementation

[0018] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application.

[0019] This application provides a quasi-in-situ EBSD characterization method for electrically pulse-treated ultrathin metal strips. The method involves performing initial and subsequent electrical pulse treatments on the same ultrathin metal strip sample according to the sequence of the electrical pulse treatment process, and performing EBSD characterization on corresponding observation areas at different electrical pulse treatment stages to obtain microstructural information such as grain morphology, grain orientation, and grain boundary distribution in the observation area at different electrical pulse treatment stages.

[0020] It should be noted that the "quasi-in-situ observation area" in the embodiments of this application refers to the observation area determined on the ultrathin metal strip sample during the initial EBSD characterization. Subsequent EBSD characterization of the quasi-in-situ observation area refers to, after the ultrathin metal strip sample has undergone subsequent electrical pulse treatment and subsequent electrolytic polishing, re-determining the area corresponding to the initially determined quasi-in-situ observation area on the same ultrathin metal strip sample, and then performing EBSD characterization on the re-determined area. "Initial" and "subsequent" are used to distinguish the order of the processing stages in this method. The initial electrical pulse treatment and each subsequent electrical pulse treatment are applied to the same ultrathin metal strip sample according to the order of the electrical pulse treatment process, and do not indicate that each stage is an independent electrical pulse treatment process.

[0021] In some embodiments of this application, the ultra-thin metal strip can be a metal strip with a thickness in the micrometer range that can undergo electrical pulse treatment, electropolishing, and EBSD characterization. The following description uses cold-rolled stainless steel ultra-thin strip as an example; the thickness of the cold-rolled stainless steel ultra-thin strip can be tens of micrometers. This material and thickness are used to illustrate the specific implementation process of the method in this application and do not constitute a limitation on the type and thickness of the ultra-thin metal strip material.

[0022] Next, the solution provided by the embodiments of this application will be described in conjunction with the accompanying drawings: like Figure 1 As shown, the quasi-in-situ EBSD characterization method for electrically pulse-treated metal ultrathin strips provided in this application embodiment may include steps S100 to S600: Step S100: Obtain a metal ultrathin strip sample.

[0023] Specifically, based on the ultrathin metal strip to be studied and the EBSD observation range, a thin metal strip sample capable of undergoing electrical pulse processing and EBSD characterization is prepared. The ultrathin metal strip sample has an area through which the power supply pulse current passes and a sample surface for EBSD characterization. The ultrathin metal strip sample can be obtained directly from a pre-prepared strip sample or from a larger ultrathin metal strip after cutting. This application does not limit the specific method of obtaining the ultrathin metal strip sample.

[0024] Step S200: The ultrathin metal strip sample is subjected to initial electrical pulse treatment and initial electrolytic polishing treatment in sequence.

[0025] In practice, the ultrathin metal strip sample is placed in an electrical pulse treatment device, and an electrical pulse current flows through it to bring the sample to the initial electrical pulse treatment state required for the study. After the initial electrical pulse treatment, the sample is removed from the device and subjected to an initial electrolytic polishing treatment. This initial electrolytic polishing treatment removes the oxide layer formed on the sample surface after the initial electrical pulse treatment, ensuring the sample surface meets the requirements for initial EBSD characterization.

[0026] Step S300: Determine the quasi-in-situ observation area on the ultrathin metal strip sample and perform the initial EBSD characterization on the quasi-in-situ observation area.

[0027] Specifically, the ultrathin metal strip sample that has undergone initial electropolishing can be placed on the sample stage of a scanning electron microscope. A quasi-in-situ observation area is determined on the surface of the ultrathin metal strip sample, and its position on the sample is recorded. Subsequently, initial EBSD characterization is performed on the quasi-in-situ observation area to obtain the microstructure information of the ultrathin metal strip sample at the current electropulse processing stage.

[0028] In step S400, the ultrathin metal strip sample is subjected to subsequent electrical pulse treatment and subsequent electropolishing treatment in sequence. The processing time of the subsequent electropolishing treatment is shorter than that of the initial electropolishing treatment.

[0029] Specifically, after the initial EBSD characterization, the same ultrathin metal strip sample was removed from the scanning electron microscope, and subsequent electrical pulse treatments were performed on the sample according to the order of the electrical pulse treatment process, thus transitioning the sample from the initial electrical pulse treatment stage to the subsequent electrical pulse treatment stage. Therefore, the initial and subsequent electrical pulse treatments correspond to different processing stages reached sequentially within the same electrical pulse treatment process. After the subsequent electrical pulse treatment, the ultrathin metal strip sample underwent electrolytic polishing to remove the oxide layer that reformed on the sample surface after the subsequent electrical pulse treatment.

[0030] The initial electropolishing process is used to prepare the sample surface after the initial electro-pulse treatment. Its processing time must be sufficient to remove the oxide layer formed during the initial electro-pulse treatment and to allow the sample surface to undergo initial EBSD characterization. Subsequent electropolishing processes deal with sample surfaces that have already undergone the previous electropolishing and EBSD characterization stages, and which have subsequently reformed oxide layers due to subsequent electro-pulse treatments. Therefore, each subsequent electropolishing process uses a shorter processing time than the initial electropolishing process. This allows for the removal of the reformed oxide layer and restoration of the sample surface to a state suitable for EBSD characterization, while minimizing further removal of the already characterized sample surface material.

[0031] Step S500: Perform subsequent EBSD characterization on the in-situ observation area.

[0032] In practice, the ultrathin metal strip sample, after subsequent electropolishing, is repositioned on the scanning electron microscope stage. Based on the position of the quasi-in-situ observation area recorded during the initial EBSD characterization, and in conjunction with the edge contour, surface feature areas, or pre-defined positioning areas of the ultrathin metal strip sample, the position of the quasi-in-situ observation area on the current sample surface is redefined. Subsequently, the redefined quasi-in-situ observation area undergoes further EBSD characterization to obtain the microstructure information of the ultrathin metal strip sample after this subsequent electropulse treatment.

[0033] The initial EBSD characterization data and subsequent EBSD characterization data correspond to the microstructure of the same ultrathin metal strip sample at different stages of the electrical pulse treatment process. They can be used to compare the microstructure changes in the quasi-in-situ observation area at different stages of electrical pulse treatment.

[0034] Step S600: Repeat the subsequent electrical pulse processing step, the subsequent electropolishing processing step, and the subsequent EBSD characterization step at least once.

[0035] In practice, after obtaining subsequent EBSD characterization data, the same ultrathin metal strip sample is subjected to subsequent electrical pulse treatment again. After the initial treatment, a subsequent electropolishing treatment with a shorter processing time than the initial electropolishing treatment is performed. Subsequently, the ultrathin metal strip sample is reset on the scanning electron microscope stage, and the quasi-in-situ observation area is located again according to the position recorded during the initial EBSD characterization. Subsequent EBSD characterization is then performed with the quasi-in-situ observation area aligned with the quasi-in-situ observation area.

[0036] The above process should be repeated at least once more to obtain EBSD characterization data for the initial electrical pulse processing stage and at least two subsequent electrical pulse processing stages. This process can be continued if more electrical pulse processing stages need to be studied.

[0037] When using the above method, after the initial electrical pulse treatment and after each subsequent electrical pulse treatment, the metal ultrathin strip sample is subjected to electrolytic polishing to remove the oxide layer formed on the sample surface after the electrical pulse treatment, reduce the influence of the oxide layer on EBSD characterization, and enable the EBSD characterization results obtained at each treatment stage to truly reflect the microstructure of the metal ultrathin strip at the corresponding treatment stage. Based on this, by making the processing time of subsequent electropolishing treatment shorter than that of the initial electropolishing treatment, the oxide layer formed by subsequent electropulse treatment can be removed while reducing the removal of surface material of the sample by subsequent electropolishing treatment. This avoids significant changes in the observed surface due to excessively long subsequent electropolishing time, and ensures that the observed areas characterized by different treatment stages maintain a good correspondence, thereby improving the accuracy of EBSD characterization results obtained from different treatment stages.

[0038] In summary, by performing initial EBSD characterization on the quasi-in-situ observation area, followed by subsequent EBSD characterization after electrical pulse processing and electropolishing, the microstructure information of the quasi-in-situ observation area at different stages of electrical pulse processing can be obtained. By repeating the subsequent electrical pulse processing, electropolishing, and EBSD characterization at least once, the changes in the microstructure of the quasi-in-situ observation area at different stages of electrical pulse processing can be compared. This allows for a true and accurate characterization of the changes in the microstructure of the ultrathin metal strip as the electrical pulse processing progresses, which helps in analyzing the effect of electrical pulse processing on the microstructure of the ultrathin metal strip and provides a basis for selecting electrical pulse processing parameters.

[0039] In some embodiments, during the initial electropolishing treatment and each subsequent electropolishing treatment, the temperature of the electropolishing solution is -20℃ to -10℃, the electropolishing voltage is 15V to 20V, and the electropolishing current is 0.4A to 0.6A.

[0040] In practice, before starting the electropolishing process, the temperature of the electropolishing solution is adjusted to -20℃ to -10℃, and then the electropolishing voltage and current are set. During the electropolishing process, the temperature, voltage, and current of the electropolishing solution are monitored and kept within the above-mentioned ranges. The specific temperature, voltage, and current used for the initial electropolishing treatment and subsequent electropolishing treatments can be the same, or they can be selected within the above-mentioned ranges according to the surface condition of the sample at the corresponding treatment stage.

[0041] For example, during the initial electropolishing treatment, the temperature of the electropolishing solution can be set to -15℃, the electropolishing voltage to 15V, and the electropolishing current to 0.6A. For subsequent electropolishing treatments, the temperature of the electropolishing solution can be set to -20℃ to -15℃ (specifically -20℃, -18℃, or -15℃), the electropolishing voltage can be set to 15V to 18V (specifically 15V, 16V, 17V, or 18V), and the electropolishing current can be set to 0.4A to 0.6A (specifically 0.4A, 0.45A, 0.5A, 0.55A, or 0.6A).

[0042] Maintaining the electropolishing solution between -20℃ and -10℃ ensures it remains at a low temperature, suppressing the reaction rate and surface temperature rise during the electropolishing process. Limiting the electropolishing voltage and current within this range ensures relative stability in the electrochemical removal process of the extremely thin metal strip sample surface. Therefore, the initial electropolishing treatment and all subsequent electropolishing treatments are conducted under these controlled conditions, guaranteeing the stable execution of the electropolishing process.

[0043] Specifically, in this embodiment, the processing time for the initial electropolishing treatment is 10s to 30s, and the processing time for each subsequent electropolishing treatment is 1s to 2s. For example, the processing time for the initial electropolishing treatment can be 10s, 20s, or 30s; the processing time for each subsequent electropolishing treatment can be 1s or 2s.

[0044] The initial electropolishing treatment is used to treat the sample surface before initial EBSD characterization. When the oxide layer formed after the initial pulse treatment is thin, the treatment time can be selected from 10s to 20s; when the oxide layer is thick, the treatment time can be selected from 20s to 30s. Subsequent electropolishing treatments are for sample surfaces that have undergone the previous electropolishing stage and have reformed an oxide layer due to subsequent pulse treatments. A treatment time of 1s can be used initially; if further removal of the oxide layer is required, the treatment time can be extended to 2s.

[0045] Within the aforementioned range of electropolishing solution temperature, electropolishing voltage, and electropolishing current, limiting the processing time of each subsequent electropolishing treatment to 1-2 seconds can prevent the oxide layer on the sample surface from being ineffectively removed due to excessively short processing times, and also reduce the possibility of excessive removal of surface material due to excessively long processing times. Therefore, when repeatedly performing electrical pulse treatment and electropolishing treatment, the impact on the microstructure of the already characterized observation area can be reduced.

[0046] In some embodiments, liquid nitrogen is added to the electropolishing solution before the initial electropolishing treatment and each subsequent electropolishing treatment to adjust the temperature of the electropolishing solution to -20°C to -10°C. Specifically, liquid nitrogen can be added to the electropolishing solution in stages, and the temperature of the electropolishing solution can be measured between adjacent additions of liquid nitrogen. Once the temperature of the electropolishing solution reaches -20°C to -10°C, the ultrathin metal strip sample is placed at the electropolishing position and the electropolishing treatment begins.

[0047] For example, a portion of liquid nitrogen can be added first to bring the temperature of the electropolishing solution close to the desired temperature. Then, a small amount of liquid nitrogen can be added based on the measured temperature to prevent the temperature of the electropolishing solution from falling below the set range. Liquid nitrogen absorbs heat from the electropolishing solution and vaporizes, which can quickly lower the temperature of the electropolishing solution and is less likely to leave residues, thus reducing the impact of the cooling process on the composition of the electropolishing solution. Adjusting the temperature of the electropolishing solution in the above manner before each electropolishing treatment ensures that the initial electropolishing treatment and all subsequent electropolishing treatments begin within the set low temperature range, reducing the impact of different initial temperatures on the surface treatment degree of the sample.

[0048] In some embodiments, the current, frequency, and duty cycle of each subsequent electrical pulse processing are the same as those of the initial electrical pulse processing.

[0049] In practice, the current, frequency, and duty cycle are kept constant during each electrical pulse treatment. Different treatment stages are formed by increasing the cumulative electrical pulse treatment time, so that the main difference between each stage is concentrated in the electrical pulse treatment time. By combining the EBSD characterization of the same observation area in each treatment stage, the microstructural changes in the observation area can be compared according to the cumulative electrical pulse treatment time, reducing the influence of simultaneous changes in electrical pulse parameters on the comparison results.

[0050] In some embodiments, the location of the quasi-in-situ observation area can be determined based on the edge contour, surface feature region, or preset positioning region of the ultrathin metal strip sample. These three positioning criteria can be used individually or in combination.

[0051] Specifically, when determining the quasi-in-situ observation area based on the edge contour, the quasi-in-situ observation area can be determined according to the relative position between the quasi-in-situ observation area and the edge of the ultrathin metal strip sample. When determining the quasi-in-situ observation area based on surface feature areas, an area on the sample surface that can be identified under a scanning electron microscope can be selected as a positional reference. When determining the quasi-in-situ observation area based on a preset positioning area, a positional reference for subsequent searches can be selected before the initial EBSD characterization, and the relative position between the quasi-in-situ observation area and the preset positioning area can be determined.

[0052] During subsequent EBSD characterization, the current edge contour, surface feature region, or preset positioning region of the ultrathin metal strip sample can be compared with the position recorded during the initial EBSD characterization to re-locate the quasi-in-situ observation area. Using one or more position references can reduce the difficulty in locating the original observation area after the sample has been moved and reset, ensuring that each EBSD characterization targets the quasi-in-situ observation area on the same sample.

[0053] In some embodiments, after the initial electropolishing treatment and before determining the quasi-in-situ observation area, and after each subsequent electropolishing treatment and before performing the corresponding subsequent EBSD characterization, the metal ultrathin strip sample is ultrasonically cleaned with anhydrous ethanol and dried with an inert gas.

[0054] In practice, the electropolished metal strip sample is placed in anhydrous ethanol for ultrasonic cleaning, causing the electropolishing solution and impurities adhering to the sample surface to detach. After ultrasonic cleaning, the sample surface is purged with an inert gas until no obvious liquid residue remains. The inert gas can be nitrogen or argon.

[0055] Completing the above cleaning and drying before determining the quasi-in-situ observation area and performing each subsequent EBSD characterization can reduce the impact of electrolytic polishing solution and impurity residue on the observation area search and EBSD characterization, and ensure that the initial EBSD characterization and each subsequent EBSD characterization are performed on a clean and dry sample surface.

[0056] In some embodiments, obtaining the ultrathin metal strip sample includes wire cutting, ultrasonic cleaning, and cold air drying. Specifically, the cutting size of the ultrathin metal strip is determined based on the clamping distance of the electrical pulse processing device and the size of the observation area required for quasi-in-situ EBSD characterization, ensuring that both ends of the cut ultrathin metal strip can be clamped by the electrical pulse processing device, and that an area for EBSD characterization is reserved between the ends. Subsequently, the ultrathin metal strip is wire-cut to obtain the cut ultrathin metal strip.

[0057] After wire cutting, the ultra-thin metal strip is ultrasonically cleaned in anhydrous ethanol to remove oil, cutting residue, and impurities adhering to its surface during the wire cutting process. For example, the ultrasonic cleaning time can be 1 minute. After ultrasonic cleaning, the surface of the ultra-thin metal strip is blown with cold air until no obvious liquid residue remains, yielding an ultra-thin metal strip sample.

[0058] Determining the cutting size based on the clamping distance of the electrical pulse processing device and the size of the observation area allows the ultrathin metal strip sample to simultaneously meet the clamping requirements of the electrical pulse processing device and the observation requirements of quasi-in-situ EBSD characterization. Ultrasonic cleaning and cold air drying after wire cutting prevent cutting residues from entering subsequent electrical pulse processing, electropolishing, and EBSD characterization processes.

[0059] In some embodiments, the electropolishing solution used in the initial electropolishing treatment and each subsequent electropolishing treatment is a mixture of perchloric acid and anhydrous ethanol, wherein the volume fraction of perchloric acid in the mixture is 10% to 20%.

[0060] When preparing an electrolytic polishing solution, perchloric acid and anhydrous ethanol can be measured separately according to the required volume fraction of perchloric acid, and then the perchloric acid and anhydrous ethanol can be mixed to obtain the electrolytic polishing solution. For example, the volume fraction of perchloric acid in the mixture can be 10%, 12%, 15%, 18%, or 20%. When the volume fraction of perchloric acid is 15%, the volume ratio of perchloric acid to anhydrous ethanol is 15:85.

[0061] The initial electropolishing treatment and all subsequent electropolishing treatments can use an electropolishing solution with the same composition to reduce treatment differences caused by variations in the composition of the electropolishing solution. Within the above-mentioned volume fraction range, the specific volume fraction of perchloric acid can be selected based on the material of the extremely thin metal strip and the surface condition of the sample.

[0062] In some embodiments, the processing time for each subsequent electropolishing treatment is 1 / 30 to 1 / 5 of the processing time of the initial electropolishing treatment. Once the processing time of the initial electropolishing treatment is determined, the processing time for each subsequent electropolishing treatment can be selected within 1 / 30 to 1 / 5 of that initial processing time. The processing time for each subsequent electropolishing treatment can be the same, or it can be selected separately based on the oxidation state of the sample surface after the corresponding subsequent electrical pulse treatment.

[0063] By setting the aforementioned relative time relationships, subsequent electropolishing treatments can be made significantly shorter than the initial electropolishing treatment without limiting the specific time of the initial treatment and each subsequent electropolishing treatment. Limiting the treatment time of each subsequent electropolishing treatment within the aforementioned ratio range can reduce the likelihood of excessive removal of surface material from the sample due to subsequent treatment times being too close to the initial treatment time.

[0064] The above characterization method is further illustrated below with a specific embodiment: In this embodiment, a metal ultrathin strip sample is prepared using cold-rolled stainless steel ultrathin strip. Based on the clamping distance of the electrical pulse processing device and the size of the observation area required for quasi-in-situ EBSD characterization, the cold-rolled stainless steel ultrathin strip is cut using wire cutting. The cut metal ultrathin strip sample is ultrasonically cleaned in anhydrous ethanol for 1 min, and then dried with cold air to obtain the metal ultrathin strip sample.

[0065] The dried metal ultrathin strip sample was placed in an electrical pulse treatment device. The electrical pulse current was set to 2A, the frequency to 100Hz, and the duty cycle to 10%. The metal ultrathin strip sample underwent an initial electrical pulse treatment for 30 seconds. After treatment, the metal ultrathin strip sample was removed from the electrical pulse treatment device.

[0066] An electropolishing solution with a perchloric acid volume fraction of 15% was prepared, i.e., the volume ratio of perchloric acid to anhydrous ethanol was 15:85. Liquid nitrogen was added to the electropolishing solution to adjust its temperature to -15℃. The electropolishing voltage was set to 15V and the electropolishing current to 0.6A. The initial electropolishing treatment was performed on the ultrathin metal strip sample after the initial electrical pulse treatment for 10s.

[0067] After the initial electropolishing treatment, the ultrathin metal strip sample was ultrasonically cleaned with anhydrous ethanol and then dried with nitrogen. The sample was then placed on the stage of a scanning electron microscope, and the quasi-in-situ observation area was determined based on the sample's edge contour and surface feature regions. Initial EBSD characterization was performed on the quasi-in-situ observation area, and its location was recorded.

[0068] After the initial EBSD characterization, the same ultrathin metal strip sample was repositioned in the electro-pulse processing device. With the pulse current, frequency, and duty cycle remaining constant, a subsequent pulse processing session of 10 s was performed, bringing the total pulse processing time to 40 s. Subsequently, the ultrathin metal strip sample underwent electro-polishing in an electro-polishing solution at -20°C, with an electro-polishing voltage of 15 V, an electro-polishing current of 0.5 A, and a processing time of 1 s.

[0069] After subsequent electropolishing, the ultrathin metal strip sample was ultrasonically cleaned with anhydrous ethanol and dried with nitrogen. The sample was then repositioned on the scanning electron microscope stage. Based on the sample edge contour and surface feature areas recorded during the initial EBSD characterization, the quasi-in-situ observation area was re-identified, and subsequent EBSD characterization was performed on the quasi-in-situ observation area.

[0070] The ultrathin metal strip samples were further subjected to subsequent electrical pulse treatments using the method described above, with the cumulative electrical pulse treatment times reaching 60 s and 80 s respectively. After each subsequent electrical pulse treatment, a subsequent electropolishing treatment was performed in an electropolishing solution at -15℃, with an electropolishing voltage of 15V, an electropolishing current of 0.6A, and a treatment time of 2 s. After each subsequent electropolishing treatment, the ultrathin metal strip samples were ultrasonically cleaned with anhydrous ethanol and dried with nitrogen gas before the quasi-in-situ observation area was re-identified and subsequent EBSD characterization was performed.

[0071] Through the above processing, EBSD characterization data of the quasi-in situ observation area can be obtained when the cumulative electrical pulse treatment time is 30s, 40s, 60s and 80s, so as to compare the micro-tissue changes of the same quasi-in situ observation area at different electrical pulse treatment stages.

[0072] It should be noted that the cold air drying in the above embodiments can be replaced by inert gas drying. The inert gas can be nitrogen or argon. When using inert gas drying, the sample surface can be less affected by the external environment again during the drying process. The specific temperature, voltage, and current of each of the subsequent electropolishing treatments can also be selected within the range defined in the claims, and this application does not limit them.

[0073] The above descriptions are specific embodiments of this application, used to illustrate the technical solution of this application, and are not intended to limit the scope of protection of this application. Equivalent changes or substitutions made by those skilled in the art based on the disclosure of this application should fall within the scope defined by the claims of this application.

Claims

1. A quasi-in-situ EBSD characterization method for electrically pulse-treated ultrathin metal strips, characterized in that, include: Obtaining extremely thin metal strip samples; The metal ultrathin strip sample was subjected to initial electrical pulse treatment and initial electrolytic polishing treatment in sequence; A quasi-in-situ observation region was determined on the extremely thin metal strip sample, and the quasi-in-situ observation region was initially characterized by EBSD. The metal ultrathin strip sample is subjected to subsequent electrical pulse treatment and subsequent electrolytic polishing treatment in sequence; wherein the processing time of the subsequent electrolytic polishing treatment is shorter than the processing time of the initial electrolytic polishing treatment; The quasi-in-situ observation area was then characterized by EBSD. The subsequent electrical pulse processing, the subsequent electropolishing processing, and the subsequent EBSD characterization are repeated at least once.

2. The quasi-in-situ EBSD characterization method for electrically pulse-treated metallic ultrathin strips according to claim 1, characterized in that, During the initial electropolishing treatment and each subsequent electropolishing treatment, the temperature of the electropolishing solution is -20℃ to -10℃, the electropolishing voltage is 15V to 20V, and the electropolishing current is 0.4A to 0.6A.

3. The quasi-in-situ EBSD characterization method for electrically pulse-treated metallic ultrathin strips according to claim 2, characterized in that, The initial electropolishing treatment takes 10s to 30s, and each subsequent electropolishing treatment takes 1s to 2s.

4. The quasi-in-situ EBSD characterization method for electrically pulse-treated metallic ultrathin strips according to claim 2, characterized in that, Prior to the initial electropolishing treatment and each subsequent electropolishing treatment, the characterization method further includes: Liquid nitrogen is added to the electropolishing solution to adjust the temperature of the electropolishing solution to -20℃ to -10℃.

5. The quasi-in-situ EBSD characterization method for electrically pulse-treated metallic ultrathin strips according to claim 1, characterized in that, The current, frequency, and duty cycle of each subsequent electrical pulse processing are the same as those of the initial electrical pulse processing.

6. The quasi-in-situ EBSD characterization method for electrically pulse-treated metallic ultrathin strips according to claim 1, characterized in that, The determination of the quasi-in-situ observation area includes: The location of the quasi-in-situ observation area is determined based on at least one of the edge contour, surface feature region, and preset positioning region of the ultrathin metal strip sample.

7. The quasi-in-situ EBSD characterization method for electrically pulse-treated metallic ultrathin strips according to claim 1, characterized in that, The characterization method further includes, after the initial electropolishing treatment and before determining the quasi-in-situ observation area, and after each subsequent electropolishing treatment and before performing the subsequent EBSD characterization: The metal ultrathin strip sample was ultrasonically cleaned with anhydrous ethanol and then dried with inert gas.

8. The quasi-in-situ EBSD characterization method for electrically pulse-treated metallic ultrathin strips according to claim 1, characterized in that, The process of obtaining the extremely thin metal strip sample includes: Based on the clamping distance of the electrical pulse processing device and the size of the observation area required for quasi-in-situ EBSD characterization, wire cutting of the ultra-thin metal strip is performed to obtain the cut metal strip part. The metal ultrathin strip cut part was ultrasonically cleaned in anhydrous ethanol and then dried with cold air to obtain the metal ultrathin strip sample.

9. The quasi-in-situ EBSD characterization method for electrically pulse-treated metallic ultrathin strips according to claim 1, characterized in that, The electropolishing solution used in the initial electropolishing treatment and each subsequent electropolishing treatment is a mixture of perchloric acid and anhydrous ethanol, wherein the volume fraction of perchloric acid in the mixture is 10% to 20%.

10. The quasi-in-situ EBSD characterization method for electrically pulse-treated metallic ultrathin strips according to claim 1, characterized in that, The processing time for each subsequent electropolishing treatment is 1 / 30 to 1 / 5 of the processing time for the initial electropolishing treatment.

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