A method for characterizing the interface orientation of a polycrystalline material

Abstract

This invention discloses a method for characterizing the interface orientation of polycrystalline materials, belonging to the field of crystallography and materials characterization technology. The method involves depositing a protective layer on the target interface using a focused ion beam followed by etching, and acquiring scan images of the sample surface and the etched surface. The angles between the interface traces on the sample surface and the etched surface and the sample coordinate system are measured. After manually tilting and correcting the angle measured on one side, the interface normal is calculated using the cross product of the direction vectors of the traces on the sample surface and the etched surface. This method eliminates the need for multiple sample rotations, acquiring all required data in a single scan, thus significantly improving characterization efficiency. It is suitable for large-scale automated interface orientation measurement, providing strong technical support for the study of the microscopic mechanisms of polycrystalline materials.

Description

Technical Field

[0001] This invention relates to the fields of crystallography and materials characterization, specifically to a method for characterizing the interface orientation of polycrystalline materials. Background Technology

[0002] Polycrystalline materials typically contain numerous interfaces, such as grain boundaries, twin boundaries, and phase boundaries. The orientation of these interfaces significantly influences the material's microstructure evolution, chemical properties, and mechanical properties. Accurate characterization of interface orientation is not only fundamental to studying the deformation, phase transformation, and microscopic mechanisms of polycrystalline materials, but also crucial for predicting material microstructure evolution, optimizing mechanical properties, addressing material failure issues, and guiding material design and fabrication.

[0003] Currently, compared with traditional grain boundary orientation characterization methods (such as continuous section method, two-surface trace method, three-dimensional reconstruction method and stereoscopic method), the method based on focused ion beam (FIB) etching to characterize interface orientation has greater flexibility. It can combine multiple characterization methods such as electron backscatter diffraction (EBSD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) in the same device to perform directional analysis on grain boundaries with specific characteristics.

[0004] Traditional FIB characterization procedures typically include the following steps: (1) establishing a three-dimensional sample coordinate system on the sample surface; (2) placing the sample in a dual-beam focused ion beam scanning electron microscope (FIB-SEM), adjusting the sample stage to a horizontal position, finding the target interface and rotating it horizontally until it is parallel to the Y-axis of the electron microscope coordinate system, while manually recording the rotation angle; then keeping the target interface parallel to the Y-axis of the electron microscope coordinate system, moving the target interface to the center of the electron microscope view; (3) rotating the sample stage around the X-axis of the electron microscope coordinate system so that the sample surface is perpendicular to the focused ion beam, using... A focused ion beam is used to deposit and etch on the sample surface corresponding to the target interface to form an etched surface perpendicular to the sample surface; (4) The etched surface is scanned by an electron beam to obtain the angle between the interface trace of the target interface on the etched surface and the Z-axis of the sample coordinate system. After correcting the angle, the normal vector of the target interface is calculated using the angle. The cross product of the normal vector of the target interface and the sample rotation matrix is ​​the normal vector of the target interface in the sample coordinate system; (5) Finally, the sample stage is rotated to a horizontal position, and steps (2)-(4) are repeated to characterize other interfaces. This process not only requires multiple adjustments to the sample stage angle and manual positioning of the target grain boundary, but also requires manual recording of rotation data, resulting in cumbersome operation and long experimental cycle, making it difficult to meet the requirements of large-scale and high-efficiency interface orientation characterization.

[0005] Furthermore, although modern dual-beam electron microscopy (DEM) equipment is equipped with automated micro / nano fabrication procedures, existing FIB characterization processes still largely rely on manual operation, making it impossible to achieve fully automated measurement of interface orientation. This technological bottleneck not only limits comprehensive statistical analysis of interface orientation in polycrystalline materials but also hinders a deeper understanding of material microstructure evolution, deformation mechanisms, and failure behavior. Therefore, developing an efficient and automated interface orientation characterization method has significant scientific and practical value. Summary of the Invention

[0006] In view of the above-mentioned shortcomings of the existing technology, the purpose of this invention is to provide a method for characterizing the interface orientation of polycrystalline materials, which solves the problems that existing interface orientation characterization methods are cumbersome to operate, have long experimental cycles, and are difficult to meet the needs of large-scale and high-efficiency interface orientation characterization.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0008] A method for characterizing the interface orientation of polycrystalline materials includes the following steps:

[0009] (1) Establish a sample coordinate system XYZ on the smooth surface of the polycrystalline sample; and make the Z-axis perpendicular to the sample surface, and the X-axis and Y-axis parallel to the sample surface and perpendicular to each other;

[0010] (2) Place the sample in a dual-beam focused ion beam scanning electron microscope, rotate the electron microscope sample stage so that the sample surface is perpendicular to the focused ion beam, and use the focused ion beam to deposit a protective layer and etch on the sample surface part corresponding to the target interface in sequence to form an etched surface perpendicular to the sample surface.

[0011] (3) Use an electron beam to scan and image the sample surface and the etched surface simultaneously. Based on the scanned image, measure the angle α between the interface trace of the target interface on the sample surface and the X-axis, and the angle β' between the interface trace of the target interface on the etched surface and the Z-axis. Then, perform tilt correction on β' to obtain the corrected angle β.

[0012] (4) Calculate the direction vector v1 of the interface trace on the sample surface and the direction vector v2 of the interface trace on the etched surface according to α and β respectively. The cross product of v1 and v2 is the normal vector n of the target interface in the sample coordinate system, thus completing the characterization of the interface orientation of the polycrystalline material.

[0013] Furthermore, in step (3), the correction formula for the angle between the interface trace on the etched surface and the Z-axis is:

[0014] β=atan((tan(β') / cos(θ))×sin(θ))

[0015] θ is the rotation angle of the electron microscope sample stage in step (2).

[0016] Furthermore, in step (4), the expressions for v1 and v2 are:

[0017] v1 = (cos(α), sin(α), 0)

[0018] v2 = (-sin(β), 0, cos(β)).

[0019] Furthermore, in step (2), the ion beam current is 20kV / 240pA when depositing the protective layer; and the ion beam current is 20kV / 4nA when etching.

[0020] Furthermore, when characterizing different target interfaces of the same sample, after the characterization of the previous target interface is completed, the sample is moved on the sample stage and steps (2)-(4) are repeated to characterize the next target interface until all target interfaces are characterized.

[0021] Furthermore, in step (3), during scanning with an electron beam, the electron beam is not parallel to either the sample surface or the etched surface. The orientation of the interface traces on both the sample surface and the etched surface is acquired simultaneously in a single scan. The electron beam direction is not parallel to either the sample surface or the etched surface because if the electron beam were parallel to a surface, that surface would appear as a line in the scan image, making it impossible to observe the interface traces on that surface.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. This invention provides a method for characterizing the interface orientation of polycrystalline materials. This method simultaneously acquires interface trace data of the target interface on the sample surface and etched surface in a single scan. Then, it combines angle measurement and tilt correction algorithms to obtain the interface trace vectors on the sample surface and etched surface. Finally, it directly obtains the interface normal vector by performing an outer product operation on the interface trace vectors. Compared to traditional FIB characterization techniques, this invention eliminates the need for multiple adjustments to the sample stage and manual recording of the horizontal rotation angle, as well as manual positioning of the target interface (i.e., moving the target interface back to the center of the electron microscope view). This greatly simplifies the operation steps and improves the accuracy and efficiency of interface orientation characterization.

[0024] 2. The method of this invention is compatible with FIB-SEM automated micro / nano fabrication systems, supports continuous etching and data acquisition of interfaces in batches, and has the potential for large-scale interface orientation measurement. It provides a standardized solution for high-throughput, high-precision characterization of interface orientation in polycrystalline materials, and is particularly suitable for microscopic mechanism research in fields such as aerospace materials and semiconductor devices. When characterizing different grain boundaries of the same polycrystalline material using the method of this invention, under the same experimental conditions and equipment, the characterization of 113 target interfaces can be successfully completed within 24 hours. In contrast, the traditional FIB characterization method can only characterize 10 target interfaces within 24 hours. The efficiency of the method of this invention is approximately ten times that of the traditional FIB characterization method. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the target interface, sample surface, and etched surface after FIB etching according to the present invention.

[0026] Figure 2 The following are schematic diagrams of the algorithm of the present invention: (a) interface scan image after etching, (b) schematic diagram of interface trace correction on the etched surface, and (c) schematic diagram of interface orientation calculation.

[0027] Figure 3 These are material scanning images obtained after etching using the method of the present invention (a) and the conventional FIB etching method (b) in Example 1;

[0028] Figure 4 These are material scanning images obtained after etching using the method of the present invention (a) and the conventional FIB etching method (b) in Example 2;

[0029] Figure 5 (a) and (b) are distribution maps obtained from the large-scale characterization of 113 interfaces in Example 3; (a) and (b) are interface distribution maps after characterizing the interfaces at different locations of the same sample using the method of the present invention. Detailed Implementation

[0030] The specific embodiments of the present invention will be described in further detail below with reference to specific examples.

[0031] I. This invention provides a method for characterizing the interface orientation of polycrystalline materials, comprising the following steps:

[0032] (1) Establish a sample coordinate system XYZ on the smooth surface of the polycrystalline sample; and make the Z-axis perpendicular to the sample surface, and the X-axis and Y-axis parallel to the sample surface and perpendicular to each other;

[0033] (2) Place the sample in a dual-beam focused ion beam scanning electron microscope (FIB-SEM), rotate the electron microscope sample stage around the X-axis of the electron microscope coordinate system so that the sample surface is perpendicular to the focused ion beam, and record the rotation angle as θ. Use the focused ion beam to deposit and etch the protective layer on the sample surface corresponding to the target interface in sequence to form an etched surface perpendicular to the sample surface.

[0034] (3) The sample surface and the etched surface are scanned and imaged simultaneously using an electron beam. Based on the scanned image, the angle α between the interface trace of the target interface on the sample surface and the X-axis and the angle β' between the interface trace of the target interface on the etched surface and the Z-axis are measured. The angle β' is then corrected by tilt correction. When scanning with an electron beam, the electron beam is not parallel to either the sample surface or the etched surface. The orientation of the interface trace of the target interface on the sample surface and the etched surface is obtained simultaneously in a single scan.

[0035] (4) Calculate the direction vector v1 of the interface trace on the sample surface and the direction vector v2 of the interface trace on the etched surface according to α and β respectively. Their cross product is the normal vector n of the target interface in the sample coordinate system.

[0036] Figure 1 This is a schematic diagram of the target interface, sample surface, and etched surface after FIB etching according to the present invention; from Figure 1 As can be seen, based on the method of this invention, after FIB etching, the target interface intersects with both the sample surface and the etched surface, and clear interface traces can be observed on both surfaces. Since both interface traces are located on the target interface, by analyzing their spatial orientation relationship in the sample coordinate system and combining it with vector outer product calculation, the three-dimensional orientation of the target interface can be directly derived.

[0037] Figure 2 a is a scanned image of the interface after etching using the method of the present invention, such as Figure 2 As shown in Figure a, interface traces of the target interface can be observed on the sample surface and the etched surface, respectively. Based on the angles between the interface traces and the sample coordinate system, v1 and v2 can be obtained:

[0038] v1 = (cos(α), sin(α), 0)

[0039] v2 = (-sin(β), 0, cos(β))

[0040] Where α is the angle between the interface trace of the target interface on the sample surface and the X-axis, and β is the angle between the interface trace of the target interface on the etched surface and the Z-axis after correction.

[0041] Figure 2 b is a schematic diagram of interface trace correction on the etched surface, such as Figure 2As shown in b, because the angles between the sample surface and the etched surface and the electron beam are different, distortion occurs when the information in the scanned image is projected onto the projection surface. Normally, the scanned image is corrected based on the angle between the sample surface and the projection surface to obtain an image consistent with the actual sample surface. However, because the angle between the etched surface and the projection surface differs from that of the sample surface, the image of the etched surface still has significant errors, thus requiring secondary correction of the etched surface. In this invention, the correction formula for the angle β between the interface trace on the etched surface and the Z-axis is:

[0042] β=atan((tan(β') / cos(θ))×sin(θ))

[0043] Where β' and β' are the original and corrected angles of the target interface trace on the etched surface relative to the Z-axis of the sample coordinate system, respectively. θ is the rotation angle of the electron microscope sample stage.

[0044] Figure 2 c is a schematic diagram of interface orientation calculation, such as Figure 2 As shown in c, the sample surface and the etched surface are perpendicular. Based on the corrected angle, the direction vector of the interface trace of the target interface on the sample surface and the etched surface can be obtained, and the orientation vector n perpendicular to the target interface in the sample coordinate system can be calculated by its outer product:

[0045] n = v1 × v2

[0046] Where v1 and v2 represent the interface trace vectors of the target interface on the sample surface and the etched surface, respectively.

[0047] II. Implementation Examples

[0048] Example 1

[0049] Studies have shown that during the deformation twinning process of Ti-15Mo alloys, the twin interfaces are generally relatively straight, and the interface orientations at different locations within the same twin are basically consistent. Therefore, this study selects the twin interfaces of Ti-15Mo alloys as the characterization target to compare the reliability of the method of this invention and the traditional FIB etching method in measuring interface orientation.

[0050] The characterization method for the twin interface of Ti-15Mo alloy provided in this embodiment includes the following steps:

[0051] S1, Sample Pretreatment

[0052] First, the Ti-15Mo alloy was placed in a muffle furnace at 900℃ and held for 1 hour before being quenched in water to obtain a Ti-15Mo alloy sample with a full β-phase microstructure.

[0053] Subsequently, a compression specimen measuring 9mm × 6mm × 6mm was cut from the Ti-15Mo alloy sample and subjected to a strain rate of 10 on a universal mechanical testing machine. -3 s -1 A compression deformation experiment with a deformation amount of 2% was conducted to form twins in the sample.

[0054] Next, the sample surface was polished smooth using 400, 800, and 2000 grit sandpaper in sequence, followed by electrolytic polishing to prepare a smooth sample surface. The polishing solution was a mixed solution of 60% (v / v) methanol, 34% (v / v) n-butanol, and 6% (v / v) perchloric acid. The specific parameters for electrolytic polishing were: voltage 30V, temperature -30℃, and time 30s.

[0055] S2, Interface Orientation Characterization

[0056] (1) Establish a sample coordinate system XYZ on the smooth sample surface, where the Z-axis is perpendicular to the sample surface, and the X-axis and Y-axis are parallel to the sample surface and perpendicular to each other.

[0057] (2) Place the sample in a Zeiss Auriga FIB-SEM dual-beam electron microscope, then rotate the sample stage 54° around the X-axis of the electron microscope coordinate system so that the sample surface is perpendicular to the focused ion beam. Move the sample so that the target interface is within the observation window. The target interface is determined by changing the magnification of the microscope to observe the position of the grain boundary. Select a grain boundary to be studied as the research object, thus completing the determination of the target interface.

[0058] (3) A protective layer is sequentially deposited and etched on the sample surface corresponding to the target interface using a focused ion beam to form an etched surface perpendicular to the sample surface. During protective layer deposition, the ion beam current is 20 kV / 240 pA; during etching, the ion beam current is 20 kV / 4 nA. In this embodiment, a platinum (Pt) layer is deposited using a focused ion beam (FIB). The principle is: a high-energy ion beam (such as gallium ions, Ga...) is used to deposit the protective layer. + The ion beam bombards the sample surface corresponding to the target interface while simultaneously injecting a platinum-containing organometallic precursor gas (such as MeCpPtMe3) onto the sample surface. The energy of the ion beam causes the precursor molecules to decompose, releasing platinum atoms that are deposited on the surface, while the organic components are converted into volatile byproducts and removed by the vacuum system. By precisely controlling the ion beam scanning path, a platinum layer with nanoscale precision is deposited layer by layer. Here, the purpose of depositing a protective layer is to ensure that the interface between the sample surface and the etched surface is well preserved during subsequent etching processes, thus exhibiting a complete right-angled morphology.

[0059] (4) Use an electron beam to scan and image the sample surface and the etched surface simultaneously. Based on the scanned images, measure the angle α between the interface trace of the target interface on the sample surface and the X-axis, and the angle β' between the interface trace of the target interface on the etched surface and the Z-axis, respectively. Then, perform tilt correction on β' to obtain the corrected angle β.

[0060] Figure 3 a is a scan image of the target interface after etching obtained in this embodiment. It can be measured from the scan image that after tilt correction, α is 111.2°; β' is -4.1°, and after secondary correction, β is -5.6°.

[0061] (5) Calculate the direction vector v1 of the interface trace on the sample surface and the direction vector v2 of the interface trace on the etched surface according to α and β respectively. Their cross product is the normal vector n of the target interface in the sample coordinate system.

[0062] Based on α and β, we can obtain v1 and v2:

[0063] v1=(cos(α),sin(α),0)=(-0.3616,0.9323,0)

[0064] v2=(-sin(β),0,cos(β))=(0.0976,0,0.9952)

[0065] The target interface normal can be represented by the outer product vector of the two vectors mentioned above:

[0066] n=v1×v2=(0.9279,0.3599,-0.0910)

[0067] To verify the reliability of the characterization method for interface orientation of the present invention, the orientation of the same twin interface was characterized using the conventional FIB etching method.

[0068] Traditional FIB etching methods for characterizing interface orientation include the following steps:

[0069] (1) Establish a sample coordinate system XYZ on the smooth Ti-15Mo alloy sample surface, where the Z axis is perpendicular to the sample surface, and the X and Y axes are parallel to the sample surface and perpendicular to each other.

[0070] (2) Place the sample in the Zeiss Auriga FIB-SEM dual-beam electron microscope and adjust the sample stage to a horizontal position to determine the target interface to be characterized. The method of determination is: by changing the magnification of the microscope, the position of the grain boundary can be observed. Select a grain boundary to be studied as the research object, and the target interface is determined.

[0071] (3) Rotate the sample stage horizontally to make the target interface parallel to the Y-axis of the electron microscope coordinate system and manually record the rotation angle. The rotation process in this experiment is as follows: rotate counterclockwise by 339.4° and record the rotation angle as α. Then keep the target interface parallel to the Y-axis of the electron microscope coordinate system and move the target interface to the center of the electron microscope view.

[0072] (4) Rotate the sample stage around the X-axis of the electron microscope coordinate system so that the sample surface is perpendicular to the focused ion beam. The rotation angle is denoted as θ. The focused ion beam is used to deposit and etch the protective layer on the sample surface corresponding to the target interface in sequence to form an etched surface perpendicular to the sample surface. During deposition, the ion beam current is 20kV / 240pA. During etching, the ion beam current is 20kV / 4nA.

[0073] (5) The etched surface is scanned and imaged using an electron beam, and the angle β' between the interface trace of the target interface on the etched surface and the Z-axis of the sample coordinate system is measured and β' is corrected to obtain β;

[0074] Figure 3 b is the etched surface scan obtained by the traditional method. As can be seen from the figure, the angle β' between the interface trace on the etched surface and the Z-axis of the sample coordinate system is -6.2°, and the true angle β after correction is -8.5°.

[0075] β=atan((tan(β') / cos(θ))×sin(θ))

[0076] (6) Calculate the normal vector v3 of the target interface using β, and calculate the normal vector n' of the target interface in the sample coordinate system based on the normal vector v3 and the rotation matrix T of the sample.

[0077] The algorithm is as follows:

[0078] After the sample stage is rotated horizontally, the normal vector of the target interface in the electron microscope coordinate system can be expressed as:

[0079] v3=(cos(β),0,sin(β))=(0.9897,0,-0.1431)

[0080] The rotation matrix T of the sample can be expressed as:

[0081]

[0082] In the sample coordinate system, the normal vector n' of the target interface can be expressed as:

[0083] n'=v3T=(0.9258,0.3480,-0.1478)

[0084] The target interface normal vectors n and n' obtained by the two methods above are very close. The slight difference mainly comes from the error of measuring the angle from the scan image, which verifies the accuracy and reliability of the method of the present invention.

[0085] Example 2

[0086] To further verify the accuracy of the method of the present invention, the interface orientation of another twin boundary in the same sample was characterized using the same experimental equipment, experimental parameters and experimental steps as in Example 1.

[0087] Figure 4 Figure a shows a scanned image of the target interface obtained by the method of the present invention. In this figure, the interface trace on the sample surface has an angle α of 61.3° with the X-axis, and the interface trace on the etched surface has an angle β' of 11.4° with the Z-axis. After correction, the angle β between the interface trace on the etched surface and the Z-axis of the sample coordinate system is 15.5°.

[0088] The interface traces of the target interface on the sample surface and the etched surface are represented by vectors as follows:

[0089] v1 = (0.4802, 0.8771, 0)

[0090] v2 = (-0.2672, 0, 0.9636)

[0091] The target interface normal can be represented by the outer product of the two vectors mentioned above:

[0092] n = (0.8452, -0.4628, 0.2344)

[0093] The twin interface described in this embodiment was characterized using the conventional FIB etching method, which is the same as the conventional FIB etching method described in Embodiment 1. The difference is that the horizontal rotation angle of the sample stage is different, which is a counterclockwise rotation of 29.4°.

[0094] The scan image of the etched surface after etching using the traditional FIB etching method is as follows: Figure 4 As shown in b, by Figure 4 As shown in b, the angle between the interface trace on the etched surface and the Z-axis of the sample coordinate system is 13.2°, and the corrected actual angle is approximately 17.9°.

[0095] After the sample stage is rotated horizontally, the normal vector of the target interface can be expressed as:

[0096] v3=(cos(β),0,sin(β))=(0.9516,0,0.3074)

[0097] The rotation matrix T of the sample can be expressed as:

[0098]

[0099] The normal vector n' of the target interface in the sample coordinate system can be expressed as:

[0100] n'=v3T=(0.8290,-0.4671,0.3074)

[0101] The target interface normal vectors n and n' obtained by the two methods above are very close. The slight difference mainly comes from the error of measuring the angle from the scan image, which verifies the accuracy and reliability of the method of the present invention.

[0102] Example 3

[0103] To verify the efficiency of the method of the present invention, a cubic sample with a side length of 4 mm was cut from an AZ31 magnesium alloy extrusion bar. First, one side of the sample was polished sequentially using 400, 800, and 2000 grit sandpaper to make its surface smooth. Then, electrolytic polishing was performed using commercial ACII magnesium alloy polishing fluid, with the polishing parameters set as follows: voltage 20V, temperature -30℃, and time 90s. After polishing, a smooth AZ31 magnesium alloy sample was obtained.

[0104] Next, the processed sample was placed in a ZeissAuriga FIB-SEM dual-beam electron microscope. The sample stage was rotated 70° around the X-axis of the electron microscope coordinate system to select the target area and capture EBSD images. The EBSD data was then processed using AZtec software to obtain the grain boundary distribution map of the target area. Based on this grain boundary distribution map and the sample surface morphology, the set of target interfaces to be characterized was selected.

[0105] Then, the interface orientation characterization method described in step S2 of Example 1 was used to sequentially characterize the selected target interfaces. Finally, the characterization of 113 target interfaces was successfully completed within 24 hours, and their interface distribution is as follows: Figure 5 As shown. Under the same operating personnel and equipment conditions, the traditional FIB etching method for characterizing interface orientation can only characterize about 10 target interfaces in 24 hours. Therefore, the efficiency of the method of the present invention is about ten times that of the traditional method.

[0106] It should be noted that when characterizing multiple interfaces of the same polycrystalline material sequentially, this invention only requires translating the sample to complete the operation, without having to rotate the sample stage multiple times or manually position the target interface, and also avoids manually recording the horizontal rotation angle.

[0107] In Examples 1 and 2, a comparison of the characterization results of the present invention's method and the traditional FIB etching method for characterizing interface orientation on two interfaces with different orientations shows that the interface normals obtained by the two methods are very close, verifying the accuracy and reliability of the present invention's method in interface orientation characterization. Example 3 further demonstrates the high efficiency of the present method in large-scale interface characterization.

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the technical solutions. Those skilled in the art should understand that any modifications or equivalent substitutions to the technical solutions of the present invention without departing from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A method for characterizing the interface orientation of polycrystalline materials, characterized in that, Includes the following steps: (1) Establish a sample coordinate system XYZ on the smooth surface of the polycrystalline sample; and make the Z-axis perpendicular to the sample surface, and the X-axis and Y-axis parallel to the sample surface and perpendicular to each other; (2) Place the sample in a dual-beam focused ion beam scanning electron microscope, rotate the electron microscope sample stage so that the sample surface is perpendicular to the focused ion beam, and use the focused ion beam to deposit a protective layer and etch on the sample surface part corresponding to the target interface in sequence to form an etched surface perpendicular to the sample surface. (3) Use an electron beam to scan and image the sample surface and the etched surface simultaneously. Based on the scanned image, measure the angle α between the interface trace of the target interface on the sample surface and the X-axis, and the angle β' between the interface trace of the target interface on the etched surface and the Z-axis. Then, perform tilt correction on β' to obtain the corrected angle β. (4) Calculate the direction vector v1 of the interface trace on the sample surface and the direction vector v2 of the interface trace on the etched surface according to α and β respectively. The cross product of v1 and v2 is the normal vector n of the target interface in the sample coordinate system, thus completing the characterization of the interface orientation of the polycrystalline material.

2. The method for characterizing the interface orientation of polycrystalline materials according to claim 1, characterized in that, In step (3), the correction formula for the angle between the interface trace on the etched surface and the Z-axis is: β=atan((tan(β') / cos(θ))×sin(θ)) θ is the rotation angle of the electron microscope sample stage in step (2).

3. The method for characterizing the interface orientation of polycrystalline materials according to claim 1, characterized in that, In step (4), the expressions for v1 and v2 are: v1 = (cos(α), sin(α), 0) v2 = (-sin(β), 0, cos(β)).

4. The method for characterizing the interface orientation of polycrystalline materials according to claim 1, characterized in that, In step (2), the ion beam current is 20kV / 240pA when depositing the protective layer; and the ion beam current is 20kV / 4nA when etching.

5. The method for characterizing the interface orientation of polycrystalline materials according to claim 1, characterized in that, When characterizing different target interfaces of the same sample, after the characterization of the previous target interface is completed, the sample is moved on the sample stage and steps (2)-(4) are repeated to characterize the next target interface until all target interfaces are characterized.

6. The method for characterizing the interface orientation of polycrystalline materials according to claim 1, characterized in that, In step (3), when scanning with an electron beam, the electron beam is not parallel to either the sample surface or the etched surface. The orientation of the interface traces of the target interface on the sample surface and the etched surface is obtained simultaneously in a single scan.

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