Quantitative channel contrast imaging method based on scanning electron microscope, electronic device and medium

Abstract

The application discloses a kind of quantitative channel contrast imaging methods based on scanning electron microscope, electronic equipment and medium, comprising: the polycrystalline sample is placed into scanning electron microscope system, determines ROI, obtains crystal data;Adjust the state of polycrystalline sample, obtain the cross-correlation diagram of backscattered electron image and diffraction contrast value image, so that backscattered electron beam scanning area and ROI coincide;In ROI, optional one position, calculate ECP under the current electron beam energy;Determine target orientation on ECP, determine the optimal path of rotating polycrystalline sample to target orientation;Get backscattered electron image before and after rotation and cross-correlation, move polycrystalline sample so that backscattered electron beam scanning area before and after rotation coincide;Adjust scanning electron microscope system by the above steps, collect a series of backscattered electron images of ROI.The application can realize the characterization and analysis of block sample dislocation, nanotwin, stacking fault and other crystal defects by scanning electron microscope.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of metal material analysis testing, and more particularly, to a quantitative channeling contrast imaging method based on a scanning electron microscope, an electronic device and a medium. BACKGROUND

[0002] In recent years, with the continuous improvement of the resolution of the scanning electron microscope (SEM), researchers have been able to directly observe dislocations in crystalline materials using a backscattered electron (BSE) detector in the scanning electron microscope. According to the relative angle between the crystal orientation of the material and the incident electron, the signal of the BSE will produce different changes, especially when the incident electron beam and the orientation of the material meet the Bragg diffraction condition, the signal of the BSE will produce a sharp mutation, so that the defects in the material such as dislocations, stacking faults and twin boundaries appear strong contrast. This contrast is called channeling contrast, and the corresponding electron beam imaging method is called electron channeling contrast imaging (ECCI). By analyzing the relationship between the contrast and the crystal orientation of the defects, the defects in the material can be quantitatively analyzed.

[0003] The most important point in the application of ECCI is to make the crystal orientation of the material and the incident electron beam form a specific Bragg diffraction condition. For single crystal materials, this process can be easily achieved in SEM: when the electron beam is scanned over a large area on the sample surface, different angles between the incident electrons and the sample will be formed as the electron beam is scanned to different positions on the sample. At this time, different positions of the image naturally correspond to different angles, and the pattern of BSE intensity change with the incident angle is called electron channeling pattern (ECP). The parallel lines in the pattern correspond one-to-one to the Kikuchi lines of the crystal orientation. According to the analysis of the electron channeling pattern, the orientation of the crystal relative to the incident direction of the electron beam can be determined, so as to guide the rotation of the sample to achieve the desired Bragg diffraction condition. However, in polycrystalline samples, it is generally not possible to obtain an electron channeling pattern in this way: the grain size of common polycrystalline samples is on the order of 1-100 um, and the angle change on a grain is generally very small, usually below 1°, through ordinary imaging scanning. However, too small an angle cannot form a resolvable electron channeling pattern. In order to achieve scanning in a large angle range on a small spatial scale, the electron optical system of the SEM can be controlled, and the swing point of the electron beam scanning can be moved on the surface of the polycrystalline sample, so as to obtain an electron channeling pattern with an angle range of nearly 5°. However, even so, it is still difficult to accurately determine the orientation of the crystal because of the limited angle. On the other hand, the orientation distribution of the grains on the surface of the polycrystalline sample can be obtained in a common SEM using EBSD (Electron backscatter diffraction). Using the grain orientation information obtained by EBSD, in principle, any grain of interest can be accurately rotated to the desired lattice orientation. Based on this idea, researchers have used EBSD information to guide quantitative ECCI analysis. However, this process is basically still in the form of manual operation, and the user needs to calculate by himself how to change the angle of the sample to meet the Bragg diffraction condition according to the specific orientation information, and manually adjust the sample stage in the SEM to achieve the calculated angle change. In the whole process, if the sample stage in the SEM is controlled to rotate and tilt to achieve the required Bragg diffraction condition, and how to ensure that the region of interest is always within the field of view during the movement without being lost, all depend on the experience and familiarity of the operator with the sample, and in actual use, it is often impossible to guarantee that the desired result can be obtained.

[0004] Therefore, it is necessary to develop a quantitative channel contrast imaging method based on a scanning electron microscope, an electronic device and a medium.

[0005] The information disclosed in the Background section of the present invention is only intended to enhance the understanding of the general background of the present invention and should not be taken as an acknowledgement or any form of suggestion that this information forms prior art that is already known to those skilled in the art. SUMMARY

[0006] The present invention provides a scanning electron microscope-based quantitative channel contrast imaging method, an electronic device and a medium.

[0007] In a first aspect, the present disclosure provides a scanning electron microscope-based quantitative channel contrast imaging method, comprising:

[0008] placing a polycrystalline sample into a scanning electron microscope system, determining a region of interest (ROI), and then obtaining crystal data, including diffraction contrast values of backscattered diffraction patterns;

[0009] adjusting the state of the polycrystalline sample, obtaining a cross-correlation map of backscattered electron images and diffraction contrast value images, and then moving the polycrystalline sample so that the backscattered electron beam scanning area coincides with the ROI;

[0010] at an optional position in the ROI, calculating an electron channeling pattern (ECP) at the current electron beam energy according to the lattice constant of this position;

[0011] determining a target orientation on the ECP, and then determining an optimal path for rotating the polycrystalline sample to the target orientation;

[0012] obtaining backscattered electron images before and after rotation and performing cross-correlation, and then moving the polycrystalline sample so that the backscattered electron beam scanning areas before and after rotation coincide;

[0013] adjusting the scanning electron microscope system through the above steps, and collecting a series of backscattered electron images of the ROI.

[0014] Preferably, placing a polycrystalline sample into a scanning electron microscope system, determining a region of interest (ROI), and then obtaining crystal data comprises:

[0015] fixing the polycrystalline sample on a multi-axis sample stage of the scanning electron microscope system, wherein Rx represents the acute angle between the X-axis rotation of the polycrystalline sample and the horizontal state, Ry represents the acute angle between the Y-axis rotation of the polycrystalline sample and the horizontal state, and at least one of Rx and Ry is 0;

[0016] determining a region of interest (ROI) on the polycrystalline sample;

[0017] determining crystal data of each position in the ROI, including diffraction contrast values of backscattered diffraction patterns

[0018] Preferably, the crystal data further comprises lattice constants, lattice orientations.

[0019] Preferably, adjusting the polycrystalline sample state, obtaining a cross-correlation map between the backscattered electron image and the diffraction contrast value image, and further moving the polycrystalline sample so that the backscattered electron beam scanning area coincides with the ROI comprises:

[0020] adjusting the polycrystalline sample to a level state where Rx and Ry are both 0;

[0021] acquiring a backscattered electron image, edge filter processing the diffraction contrast value image and the backscattered electron image, and further obtaining a cross-correlation map between the two processed images;

[0022] calculating the translation values in X and Y directions between the two processed images through the cross-correlation map, and moving the polycrystalline sample according to the calculated translation values so that the backscattered electron beam scanning area coincides with the ROI.

[0023] Preferably, determining the target orientation on the ECP comprises:

[0024] selecting any one of the relative orientations between the lattices of the materials that one wants to achieve as the target orientation on the ECP.

[0025] Preferably, determining the optimal path to rotate the polycrystalline sample to the target orientation comprises:

[0026] rotating the polycrystalline sample from the initial position to the target orientation through at least two rotation operations according to the combination of different rotation directions that the polycrystalline sample has in the scanning electron microscope system;

[0027] determining the optimal path to rotate the polycrystalline sample to the target orientation.

[0028] Preferably, acquiring the backscattered electron images before and after rotation and performing cross-correlation, and further moving the polycrystalline sample so that the backscattered electron beam scanning areas before and after rotation coincide comprises:

[0029] taking two backscattered electron images before and after the rotation operation respectively, and performing edge filter processing on the two backscattered electron images, and further calculating the cross-correlation map between the two images;

[0030] obtaining the translation data of the two backscattered electron images in X and Y directions from the cross-correlation map so that the backscattered electron beam scanning areas before and after rotation coincide.

[0031] Preferably, acquiring a series of backscattered electron images of the ROI comprises:

[0032] After the image alignment is realized by the translation data, the backscattered electron image is collected again, and the image before the rotation operation is combined to obtain the backscattered electron image after the same position and different orientation changes;

[0033] The relative orientation is changed, the image alignment is performed again, and a series of backscattered electron images at the same position and different relative orientations between material lattices are obtained.

[0034] The region of interest (ROI) is changed, and the above steps are repeated to collect a series of backscattered electron images of multiple ROIs.

[0035] In a second aspect, the embodiments of the present disclosure further provide an electronic device, which comprises:

[0036] a memory, which stores executable instructions;

[0037] a processor, which runs the executable instructions in the memory to implement the quantitative channel contrast imaging method based on a scanning electron microscope.

[0038] In a third aspect, the embodiments of the present disclosure further provide a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the quantitative channel contrast imaging method based on a scanning electron microscope.

[0039] The beneficial effects are as follows:

[0040] The present application can realize characterization and analysis of crystal defects such as dislocations, nanotwins and stacking faults of block-shaped samples by a scanning electron microscope. Compared with observation of crystal defects by a transmission electron microscope, the present test method has the advantages of simple sample preparation, low cost and high efficiency, and solves the problem of limited observation area of the transmission electron microscope. The present application can realize observation of defect distribution in a more macroscopic range, and is a powerful supplement to the function of the transmission electron microscope. Especially for observation and test of a large number of crystal defects, the present application is not only beneficial to in-depth research on deformation and microstructure evolution mechanism of engineering materials, but also promotes further development and application of related technologies in the field of backscattered electrons, and proposes analysis of crystal defects by a scanning electron microscope.

[0041] The method and device of the present application have other characteristics and advantages, which will be apparent or will be described in detail in the accompanying drawings and subsequent detailed description incorporated herein, which together serve to explain the specific principles of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0042] The above and other objects, features and advantages of the present application will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which like reference characters refer to like parts throughout the figures, and in which:

[0043] Figure 1 A flow chart showing the steps of a scanning electron microscopy based quantitative channel contrast imaging method according to one embodiment of the present application.

[0044] Figure 2 A schematic diagram of a scanning electron microscope system according to one embodiment of the present application is shown.

[0045] Figure 3a , Figure 3b , Figure 3c , Figure 3d A secondary electron image at 70° tilt, EBSD diffraction contrast values at 70° tilt, EBSD Euler angles at 70° tilt, and a backscatter image at 0° tilt of the same region of a nickel-based superalloy according to one embodiment of the present application are shown.

[0046] Figure 4a , Figure 4b A diffraction contrast image and a backscatter electron image after using edge filters according to one embodiment of the present application are shown.

[0047] Figure 5 A cross-correlation plot between a diffraction contrast image and a backscatter electron image after using edge filters according to one embodiment of the present application is shown.

[0048] Figure 6 A schematic diagram of a spherical polar plot of ECP patterns of nickel under 20 kV electron beam conditions in the direction of the

[100] principal axis according to one embodiment of the present application is shown.

[0049] Figure 7a , Figure 7b Schematic diagrams of ECP images of a particular grain in the initial state and after a change in tilt and rotation orientation according to one embodiment of the present application are shown.

[0050] Figure 8a , Figure 8b , Figure 8c A backscatter image at 0° tilt, a backscatter image at 3° tilt angle, and a cross-correlation plot between the two according to one embodiment of the present application are shown.

[0051] Figure 9a , Figure 9b , Figure 9c An edge filter image at 0° tilt, an edge filter image at 3° tilt angle, and a cross-correlation plot between the two according to one embodiment of the present application are shown.

[0052] Explanation of reference numerals in the attached figures:

[0053] 1. Electron optical tube; 2. Vacuum chamber; 3. Secondary electron detector a; 4. Backscattered electron detector a; 5. Secondary electron detector b; 6. Backscattered electron detector b; 7. Polycrystalline sample; 8. Multi-axis sample stage; 9. EBSD detector; 10. Control circuit; 11. Computer; 12. Control program. Detailed Implementation

[0054] Preferred embodiments of the invention will now be described in more detail. While preferred embodiments of the invention are described below, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0055] Figure 1 A flowchart illustrating the steps of a quantitative channel contrast imaging method based on scanning electron microscopy according to an embodiment of the present invention is shown.

[0056] like Figure 1 As shown, the present invention provides a quantitative channel contrast imaging method based on scanning electron microscopy, comprising:

[0057] Step 101: Place the polycrystalline sample into a scanning electron microscope system, determine the region of interest (ROI), and then obtain crystal data, including the diffraction contrast value of the backscattered diffraction pattern.

[0058] Step 102: Adjust the state of the polycrystalline sample to obtain the cross-correlation diagram of the backscattered electron image and the diffraction contrast value image, and then move the polycrystalline sample so that the backscattered electron beam scanning area coincides with the ROI.

[0059] Step 103: Select any location in the ROI and calculate the electron channel effect pattern (ECP) at the current electron beam energy based on the lattice constant of this location.

[0060] Step 104: Determine the target orientation on the ECP, and then determine the optimal path to rotate the polycrystalline sample to the target orientation;

[0061] Step 105: Obtain backscattered electron images before and after rotation and perform cross-correlation, then move the polycrystalline sample so that the backscattered electron beam scanning areas before and after rotation overlap.

[0062] Step 106: Adjust the scanning electron microscope system according to the above steps to acquire a series of backscattered electron images of the ROI.

[0063] In one example, a polycrystalline sample is placed in a scanning electron microscope system to determine the region of interest (ROI) and then acquire crystal data, including:

[0064] fixing the polycrystalline sample on a multi-axis sample stage of a scanning electron microscope system, wherein Rx represents an acute angle between a horizontal state and an angle of the polycrystalline sample rotated in an X direction as an axis, and Ry represents an acute angle between the horizontal state and an angle of the polycrystalline sample rotated in a Y direction as an axis, at least one of Rx and Ry being 0;

[0065] determining a region of interest (ROI) on the polycrystalline sample;

[0066] determining crystal data of each position in the ROI, including a diffraction contrast value of a backscattered diffraction pattern, in one example, the crystal data further includes a lattice constant and a lattice orientation.

[0067] in one example, adjusting the polycrystalline sample, obtaining a cross-correlation map between the backscattered electron image and the diffraction contrast value image, and then moving the polycrystalline sample so that the backscattered electron beam scans the region coincides with the ROI includes:

[0068] adjusting the polycrystalline sample to a horizontal state with both Rx and Ry being 0;

[0069] capturing a backscattered electron image, performing edge filter processing on the diffraction contrast value image and the backscattered electron image, and then obtaining a cross-correlation map between the two processed images;

[0070] calculating translation values in the X and Y directions between the two processed images through the cross-correlation map, and moving the polycrystalline sample according to the calculated translation values so that the backscattered electron beam scans the region coincides with the ROI.

[0071] in one example, determining a target orientation on the ECP includes:

[0072] selecting any one of the relative orientations between the lattices of the materials that are desired to be achieved on the ECP as the target orientation.

[0073] in one example, determining an optimal path for rotating the polycrystalline sample to the target orientation includes:

[0074] according to the different combinations of rotation directions that the polycrystalline sample has in the scanning electron microscope system, rotating the polycrystalline sample from an initial position to the target orientation through at least two rotation operations;

[0075] determining an optimal path for rotating the polycrystalline sample to the target orientation.

[0076] in one example, obtaining backscattered electron images before and after rotation and performing cross-correlation, and then moving the polycrystalline sample so that the backscattered electron beam scans the region before and after rotation coincides includes:

[0077] capturing two backscattered electron images before and after the rotation operation respectively, and performing edge filter processing on the two backscattered electron images, and then calculating a cross-correlation map therebetween;

[0078] The translation data of the two backscattered electron images in X and Y directions is obtained from the cross-correlation map, so that the backscattered electron beam scanning areas before and after rotation are overlapped.

[0079] In one example, the series of backscattered electron images of the ROI are collected by:

[0080] After the image alignment by the translation data, the backscattered electron images are collected again, combined with the images before the rotation operation, to obtain the backscattered electron images after the same position and different orientation changes.

[0081] The relative orientation is changed, the image alignment is performed again, and a series of backscattered electron images at the same position and different relative orientations between the crystal lattices are obtained.

[0082] The ROI of interest is changed, and the above steps are repeated to collect a series of backscattered electron images of multiple ROIs.

[0083] Specifically, the method uses a scanning electron microscope system, and the vacuum chamber of the scanning electron microscope system is provided with a multi-axis sample stage, a backscattered electron detector a, and an EBSD detector. The multi-axis sample stage can realize translation in X and Y directions or translation in X, Y, and Z directions. Meanwhile, the multi-axis sample stage can realize rotation around X and Y directions or rotation around X, Y, and Z directions. X, Y, and Z are three mutually perpendicular directions in geometry. The multi-axis sample stage can fix one or more polycrystalline samples. The method steps are as follows:

[0084] 1) Fix the polycrystalline sample to be observed on the multi-axis sample stage. Rx represents the acute angle between the rotation of the polycrystalline sample around the X direction and the horizontal state. Ry represents the acute angle between the rotation of the polycrystalline sample around the Y direction and the horizontal state. At least one of Rx and Ry is 0. Select one or more ROIs on the polycrystalline sample. The ROI is the region of interest. Collect the backscattered diffraction pattern by the EBSD detector and analyze the crystal data of each position in the ROI, including the lattice constant, the lattice orientation, and the band contrast of the backscattered diffraction pattern.

[0085] 2) After the crystal data is obtained, the polycrystalline sample is adjusted to a level state with Rx and Ry both being 0, and a backscattered electron image is collected by the backscattered electron detector a, and both the diffraction contrast value image of the backscattered diffraction pattern obtained by the EBSD detector and the backscattered electron image collected by the backscattered electron detector a are subjected to edge filtering, so as to obtain two processed images, and the translation values in the X and Y directions between the two processed images can be calculated by calculating the cross-correlation diagram between the two processed images, and the sample stage is moved according to the calculated translation values, so that the area scanned by the electron beam when the backscattered electron detector a images coincides with the ROI defined in step 1;

[0086] 3) An arbitrary position in the ROI is selected, and the ECP at the current electron beam energy can be calculated according to the lattice constant and the lattice orientation of the position, the ECP being an electron channeling pattern, and the pattern can calculate the position distribution of each Kirchhoff line through the Bragg diffraction formula;

[0087] 4) Any desired relative orientation between the lattices of the materials, i.e. the target orientation, is selected on the ECP generated in step 3), and the polycrystalline sample is rotated from the initial position to achieve the desired target orientation through at least two rotation operations according to the combination of different rotation directions of the sample stage; after rotating in a specific direction, the optimized rotation and tilt path is calculated to rotate the polycrystalline sample to the selected direction;

[0088] 5) Two backscattered electron images are respectively taken by the backscattered electron detector a before and after the rotation operation in step 4), and the edge filtering is performed on the two backscattered electron images, and the cross-correlation diagram between the two backscattered electron images is calculated, and the translation between the two backscattered electron images in the X and Y directions is obtained from the cross-correlation diagram; the sample stage is moved according to the calculated translation values, so that the backscattered electron beam scanning areas before and after the rotation coincide;

[0089] 6) After the image alignment is achieved through step 5), the backscattered electron image is collected again by the backscattered electron detector a, and the backscattered electron image after the change of the relative orientation between the lattices of the materials at the same position is obtained in combination with the image before the rotation operation in step 4);

[0090] 7) A series of backscattered electron images at the same position and different relative orientations between the lattices of the materials can be obtained by repeating the operations of steps 4) to 6);

[0091] 8) The data collection process of steps 2) to 7) is realized by controlling the scanning electron microscope system, and a series of backscattered electron images of a plurality of ROIs are collected.

[0092] In the process of calculating ECP, a new ECP is calculated for any position in the selected ROI each time; and ECPs of all material phases present in the material at any angle are pre-calculated and recorded, so that each time any position in the selected ROI is selected, the corresponding material phase and lattice orientation can be queried and interpolated in the general ECP database to quickly generate the corresponding ECP.

[0093] The method realizes the automatic process of quantitative ECCI analysis through EBSD, and in the whole process, the program can control the sample stage of SEM to realize various rotations and translations according to the results of EBSD, so as to realize any desired Bragg diffraction condition, and in the process of sample rotation and translation, the defined region of interest is automatically tracked according to image recognition, and nanoscale automatic tracking is realized.

[0094] The application further provides an electronic device, which comprises a memory storing executable instructions and a processor running the executable instructions in the memory to realize the quantitative channel contrast imaging method based on a scanning electron microscope.

[0095] The application further provides a computer readable storage medium storing a computer program, and the computer program is executed by a processor to realize the quantitative channel contrast imaging method based on a scanning electron microscope.

[0096] In order to facilitate understanding of the scheme and effects of the embodiments of the application, three specific application examples are given below. Those skilled in the art should understand that the examples are only for facilitating understanding of the application, and any specific details of the examples are not intended to limit the application in any way.

[0097] Example 1

[0098] Figure 2 A schematic diagram of a scanning electron microscope system according to an embodiment of the application is shown.

[0099] As Figure 2As shown, the scanning electron microscope system used in the present application is a Zeiss GEMINI 460, which includes an electron optical column 1 and a vacuum chamber 2, a multi-axis sample stage 8 for placing a polycrystalline sample 7 is arranged in the vacuum chamber 2, a secondary electron detector a 3 and a backscattered electron detector a 4 for collecting signals of the polycrystalline sample 7 are also arranged in the vacuum chamber 2, the secondary electron detector a 3 is located obliquely above the multi-axis sample stage 8, the backscattered electron detector a 4 is located directly above the multi-axis sample stage 8, the secondary electron detector b 5 and the backscattered electron detector b 6 are arranged from top to bottom in the electron optical column 1, the secondary electron detector b 5 is located below the secondary electron detector a 3 in the vacuum chamber 2 and faces the multi-axis sample stage 8 for placing the surface of the multi-axis sample stage 8, and an EBSD detector 9 is arranged for collecting the diffraction pattern of backscattered electrons; the secondary electron detector a 3, the backscattered electron detector a 4, the secondary electron detector b 5, the backscattered electron detector b 6, the multi-axis sample stage 8 and the EBSD detector 9 are all connected with a control circuit 10, the control circuit 10 is connected with a computer 11, and the computer 11 is provided with a control program 12. The computer 11 controls various imaging scanning functions of the scanning electron microscope system, the movement of the multi-axis sample stage 8 and the signal acquisition of the EBSD detector 9 through the signals transmitted by the control circuit 10. The multi-axis sample stage 8 can move in the X-axis, Y-axis and Z-axis directions in the vacuum chamber 2 and can rotate and tilt, and the polycrystalline sample 7 to be measured is adhered to the multi-axis sample stage 8 by conductive glue.

[0100] The method for realizing quantitative channel contrast imaging based on the above scanning electron microscope system comprises the following steps:

[0101] Step 1: First, the polycrystalline sample 7 is adhered to the multi-axis sample stage 8 by conductive glue in a tilted state in the scanning electron microscope system, a specific region (ROI) is selected for EBSD measurement by the EBSD detector 9, and the lattice orientation of each grain on the polycrystalline sample 7 can be obtained from the EBSD measurement results.

[0102] Step 2: The polycrystalline sample 7 is adjusted from the tilted state to the horizontal state to realize the observation of BSE using the backscattered electron detector a 4. After adjusting the tilt angle of the polycrystalline sample 7, the position information of the specific region (ROI) selected in step 1 is obtained according to the EBSD measurement results (the shape of the grain), and then the specific region (ROI) is found in the horizontally placed polycrystalline sample 7 and the electron beam is centered.

[0103] Step 3: After the end of the electron beam centering, the grain in any specific region (ROI) in the BSE image observed by the backscattered electron detector a 4 can be known, and the possible ECP pattern can be calculated according to the lattice parameters and the lattice orientation corresponding to the grain.

[0104] Step 4: Select any desired Bragg condition in the ECP pattern and calculate the rotation and tilt angles that the multi-axis sample stage 8 needs to go through to achieve this condition.

[0105] Step 5: Correct any horizontal drift of the sample during the rotation and tilt of the sample using an image cross-correlation algorithm to ensure that the ROI is always centered.

[0106] Step 6: Take an image of the BSE using the backscatter electron detector a 4 at the desired Bragg condition. Then go back to Step 4 to select a new Bragg condition or go back to Step 3 to select a new grain of interest. The user only needs to perform the selection of a specific area (ROI), selection of a grain of interest and selection of a Bragg direction in the entire workflow. The tilt of the polycrystalline sample 7, the tracking of the specific area (ROI), the calculation of the ECP pattern and the acquisition of the image of the BSE are done by the control of the scanning electron microscope to reduce the burden of manual adjustment and to increase the work efficiency.

[0107] Figure 3a 、 Figure 3b 、 Figure 3c 、 Figure 3d Figures 1A, 1B, 1C and 1D respectively show a secondary electron image at 70° tilt, an EBSD diffraction contrast value at 70° tilt, an EBSD Euler angle at 70° tilt and a backscatter image at 0° tilt of the same area of a nickel-based superalloy according to one embodiment of the application.

[0108] Figure 4a 、 Figure 4b Figures 2A and 2B respectively show a diffraction contrast image and a backscatter electron image after using an edge filter according to one embodiment of the application.

[0109] Figure 5 Figure 3 shows a cross-correlation map between a diffraction contrast image and a backscatter electron image after using an edge filter according to one embodiment of the application.

[0110] In Step 2, after reading the EBSD measurement, it is necessary to observe the ECCI by backscatter electron 4 at a smaller (acute) tilt angle. Even if the polycrystalline sample 7 is rotated back from 70° tilt to 0° tilt by a high-precision mechanical stage, there will be a drift of 10-50 pm in the observed area in practice. Therefore, it is necessary to correlate the positions of the observed area of the polycrystalline sample 7 at 70° tilt and 0° tilt under two different working conditions. It is generally difficult to find the corresponding area by directly comparing the results of EBSD and ECCI manually. Figure 3a 、 Figure 3b 、 Figure 3c 、 Figure 3dThe secondary electron image at 70° tilt and the EBSD diffraction contrast values are shown for the same sample area, as well as the backscattered electron image at 0°. From the images it can be seen that a small shift is caused by the rotation of the polycrystalline sample 7 between 0° and 70°. Considering that the samples are usually observed after surface polishing and thus lack surface topography information, the secondary electrons hardly provide any contrast, while the backscattered electrons can show the distribution of grain boundaries and the scratches on the sample surface by channeling effects, and the same grain boundary distribution and scratches can be shown by the diffraction contrast values in the EBSD results. By comparing the topography information provided by the two kinds of contrast, the working area under the two different working conditions can be accurately correlated, and thus the orientation of the grains at each position under the ECCI imaging condition can be determined. Figure 4a , Figure 4b , Figure 5 The diffraction contrast values and the backscattered electron image after using the edge filter are shown, as well as the image obtained by the cross-correlation algorithm between the two. By detecting the position of the maximum value in the image obtained by the cross-correlation algorithm, the shift of the sample under the two positions can be accurately measured.

[0111] Figure 6 A schematic diagram of the ECP pattern of nickel in the

[100] orientation under 20 kV electron beam conditions is shown.

[0112] With the knowledge of the orientation of the grains at each position in the observed area, the multi-axis sample stage 8 can be selected to rotate so as to satisfy the electron diffraction conditions of a specific crystal face on a specific grain. In the case of known crystal orientation, the effect of changing the relative angle between the incident electron beam and the sample on the backscattered signal can be deduced by numerical simulation, that is, the ECP pattern is obtained, so that all directions that satisfy the electron diffraction conditions can be displayed. This process can be calculated after selecting the grain of interest, or the backscattering coefficient can be simulated at all crystal face angles in advance by the Monte Carlo numerical method, so as to obtain the full-angle ECP pattern (ECP master pattern). In the case of obtaining the full-angle ECP pattern, a new ECP can be quickly generated for any possible crystal lattice orientation by table lookup interpolation, without repeating the Monte Carlo numerical simulation process. Figure 6 A schematic diagram of the ECP pattern of nickel in the

[100] orientation under 20 kV electron beam conditions is shown.

[0113] Figure 7a , Figure 7b Schematic diagrams of the ECP images of a specific grain in the initial state, the state after the tilt and rotation orientation are changed, respectively, are shown.

[0114] In the case of a specific grain ECP pattern, the Bragg condition to be achieved can be selected on the ECP pattern. The control software will automatically tilt and rotate the sample stage to achieve the selected angle. Figure 7a , Figure 7b The figure on the left shows the simulated ECP at 0° tilt after selecting an orientation of a specific grain. After rotating a specific direction, the optimized rotation and tilt path is calculated to place the sample in the selected direction.

[0115] Figure 7a The figure on the right shows the ECP of a specific grain in the sample at 0° tilt and rotation. A specific direction can be selected on the ECP, indicated by the yellow dot. The control software will automatically rotate and tilt the sample to achieve this direction. The sample and ECP at the new selected direction are shown on the left. Figure 7b The figure on the right.

[0116] Figure 8a , Figure 8b , Figure 8c The figures show the 0°, 3° tilt angle backscatter images and the cross-correlation of the two, respectively, according to one embodiment of the application.

[0117] Figure 9a , Figure 9b , Figure 9c The figures show the 0°, 3° tilt angle edge filter images and the cross-correlation of the two, respectively, according to one embodiment of the application.

[0118] When performing ECCI observations, the same area needs to be observed at a high magnification in a number of different tilt and rotation directions. The multi-axis sample stage 8 will inevitably cause a drift of 10-50 μm when tilting and rotating. Therefore, image recognition and tracking is needed to correct for this drift. Figure 8a , Figure 8b , Figure 8c The figures show the backscatter images of a stainless steel sample at 0° and 3° tilt. Due to the effect of electron channeling contrast, the gray scale of the grains will differ greatly in the two directions. This makes it very difficult to automatically recognize the drift of the sample, as there is hardly any significant maximum peak in the cross-correlation of the two images. However, even though the gray scale of the individual grains will vary greatly, the position of the grain boundaries will not change. Therefore, the contrast of the grain boundaries can be highlighted by using an edge filter, while the effect of the variation of the gray scale of the grains themselves is reduced. In the Figure 9a , Figure 9b , Figure 9c It can be seen that the cross-correlation after using the edge filter to adjust the brightness of the grain boundary profile can obtain a significant maximum peak, so that the drift of the sample can be accurately obtained.

[0119] Precise positioning of the sample is achieved by moving the sample stage, and BSE images are collected with the BSE probe after tilting and rotation. A series of BSE images corresponding to the region of interest are then generated by selecting the region of interest. Finally, the scanning electron microscope is used to characterize and analyze crystal defects such as dislocations, nanotwins, and stacking faults in bulk samples.

[0120] Example 2

[0121] The electronic device includes a memory storing executable instructions, and a processor running the executable instructions in the memory to implement the quantitative channel contrast imaging method based on a scanning electron microscope.

[0122] The electronic device according to an embodiment of the present disclosure includes a memory and a processor.

[0123] The memory is configured to store non-transitory computer-readable instructions. Specifically, the memory can include one or more computer program products, which can include various forms of computer-readable storage media, such as volatile memory and / or non-volatile memory. The volatile memory may, for example, include random access memory (RAM), cache memory, and / or the like. The non-volatile memory may, for example, include read-only memory (ROM), hard disk, flash memory, and / or the like.

[0124] The processor can be a central processing unit (CPU) or other form of processing unit having data processing and / or instruction execution capabilities, and can control other components in the electronic device to perform desired functions. In an embodiment of the present disclosure, the processor is configured to run the computer-readable instructions stored in the memory.

[0125] Those skilled in the art will understand that, in order to solve the technical problem of how to obtain a good user experience effect, the present embodiment can also include well-known structures such as a communication bus, an interface, and the like, which should also be included in the protection scope of the present disclosure.

[0126] Detailed descriptions of the present embodiment can be found in the corresponding descriptions of the foregoing embodiments, which will not be repeated here.

[0127] Example 3

[0128] The present embodiment provides a computer-readable storage medium storing a computer program, which is executed by a processor to implement the quantitative channel contrast imaging method based on a scanning electron microscope.

[0129] A computer readable storage medium according to embodiments of the present disclosure has non-transitory computer readable instructions stored thereon. When the non-transitory computer readable instructions are run by a processor, all or part of the steps of the method of the embodiments of the present disclosure described above are performed.

[0130] The computer readable storage medium described above includes, but is not limited to, an optical storage medium (for example, a CD-ROM and a DVD), a magneto-optical storage medium (for example, an MO), a magnetic storage medium (for example, a magnetic tape or a moving hard disk), a medium having a built-in rewritable nonvolatile memory (for example, a memory card), and a medium having a built-in ROM (for example, a ROM cartridge).

[0131] It will be understood by those skilled in the art that the above description of the embodiments of the present application is only for the purpose of exemplarily illustrating the beneficial effects of the embodiments of the present application, and is not intended to limit the embodiments of the present application to any of the examples given.

[0132] The embodiments of the present application have been described above, and the above description is exemplary, is not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A quantitative channel contrast imaging method based on scanning electron microscopy, characterized in that, include: The polycrystalline sample is placed in a scanning electron microscope system to determine the region of interest (ROI) and then crystal data, including the diffraction contrast value of the backscattered diffraction pattern, is obtained. The state of the polycrystalline sample is adjusted to obtain a cross-correlation diagram of the backscattered electron image and the diffraction contrast value image, and then the polycrystalline sample is moved so that the backscattered electron beam scanning area coincides with the ROI; Choose any location in the ROI and calculate the electron channel effect pattern (ECP) at the current electron beam energy based on the lattice constant of that location; The target orientation is determined on the ECP, and then the optimal path for rotating the polycrystalline sample to the target orientation is determined. The backscattered electron images before and after rotation are acquired and cross-correlated, and then the polycrystalline sample is moved so that the backscattered electron beam scanning areas before and after rotation overlap. By adjusting the scanning electron microscope system through the above steps, a series of backscattered electron images of the ROI are acquired.

2. The quantitative channel contrast imaging method based on scanning electron microscopy according to claim 1, wherein, The polycrystalline sample is placed in a scanning electron microscope system to determine the region of interest (ROI), and then crystal data is obtained, including: The polycrystalline sample is fixed on the multi-axis sample stage of the scanning electron microscope system, wherein Rx represents the acute angle between the polycrystalline sample rotating about the X-axis and the horizontal state, Ry represents the acute angle between the polycrystalline sample rotating about the Y-axis and the horizontal state, and at least one of Rx and Ry is 0. Determine the region of interest (ROI) on the polycrystalline sample; Determine the crystal data for each location in the ROI, including the diffraction contrast value of the backscattered diffraction pattern.

3. The quantitative channel contrast imaging method based on scanning electron microscopy according to claim 1, wherein, The crystal data also includes lattice constant and lattice orientation.

4. The quantitative channel contrast imaging method based on scanning electron microscopy according to claim 2, wherein, Adjusting the state of the polycrystalline sample to obtain a cross-correlation diagram of the backscattered electron image and the diffraction contrast value image, and then moving the polycrystalline sample so that the backscattered electron beam scanning area coincides with the ROI includes: The polycrystalline sample was adjusted to a state where both Rx and Ry were 0. Backscattered electron images are acquired, and edge filtering is applied to the diffraction contrast value image and the backscattered electron image to obtain a cross-correlation map between the two processed images. The cross-correlation plot is used to calculate the translation values ​​in the X and Y directions between the two processed images. The polycrystalline sample is then moved according to the calculated translation values ​​so that the backscattered electron beam scanning area coincides with the ROI.

5. The quantitative channel contrast imaging method based on scanning electron microscopy according to claim 1, wherein, Determining the target orientation on the ECP includes: The target orientation is any relative orientation between material lattices that is desired to be achieved on the ECP.

6. The quantitative channel contrast imaging method based on scanning electron microscopy according to claim 5, wherein, Determining the optimal path for rotating the polycrystalline sample to the target orientation includes: Based on the different combinations of rotation directions of the polycrystalline sample in the scanning electron microscope system, the polycrystalline sample is rotated from its initial position to achieve the target orientation through at least two rotation operations; Determine the optimal path to rotate the polycrystalline sample to the target orientation.

7. The quantitative channel contrast imaging method based on scanning electron microscopy according to claim 6, wherein, Acquiring backscattered electron images before and after rotation and performing cross-correlation, then moving the polycrystalline sample to make the backscattered electron beam scanning areas before and after rotation coincide, includes: Two backscattered electron images were captured before and after the rotation operation. The two backscattered electron images were then processed with an edge filter, and the cross-correlation map between them was calculated. The translation data of the two backscattered electron images in the X and Y directions are obtained from the cross-correlation plot, so that the backscattered electron beam scanning areas before and after rotation coincide.

8. The quantitative channel contrast imaging method based on scanning electron microscopy according to claim 7, wherein, The acquisition of a series of backscattered electron images of the ROI includes: After image alignment is achieved by translating data, backscattered electron images are acquired again. Combined with the image before the rotation operation, backscattered electron images are obtained after different orientation changes at the same position. By changing the relative orientation and re-aligning the images, a series of backscattered electron images are obtained under the relative orientation of different material lattices at the same location. Change the region of interest (ROI) and repeat the above steps to acquire a series of backscattered electron images of multiple ROIs.

9. An electronic device, characterized in that, The electronic device includes: Memory, which stores executable instructions; A processor that executes the executable instructions in the memory to implement the quantitative channel contrast imaging method based on scanning electron microscopy as described in any one of claims 1-8.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the quantitative channel contrast imaging method based on scanning electron microscopy as described in any one of claims 1-8.

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