Dislocation crystallography three-dimensional characterization method based on double-view-angle image

Abstract

The invention discloses a dislocation crystallography three-dimensional characterization method based on a double-view image. The method comprises the following steps: acquiring two dislocation images of a sample at different angles by using a transmission electron microscope; carrying out image registration on the dislocation image, and carrying out binarization and single-pixel processing on the registered dislocation image to obtain a dislocation line; constructing a preset coordinate system, and obtaining a space coordinate and a three-dimensional image of the dislocation line in the preset coordinate system; tilting the sample in situ to enable any crystal zone axis of the sample to be parallel to the incident direction of the electron beam, obtaining a reference orientation parameter and a tilting parameter of the sample, and obtaining a conversion parameter from a preset coordinate system to a crystal coordinate system according to the reference orientation parameter and the tilting parameter; and according to the space coordinate of the dislocation line in the preset coordinate system and the conversion parameter, obtaining the space coordinate of the dislocation line in the crystal coordinate system and a three-dimensional image. According to the method, efficient three-dimensional quantitative integrated characterization of dislocation geometrical characteristics and crystallographic characteristics in a crystal coordinate system is realized based on a double-view-angle image three-dimensional reconstruction method and a correlated crystallographic analysis technology.

Description

Technical Field

[0001] The present invention relates to the technical field of crystal material analysis, and in particular to a dislocation crystallography three-dimensional characterization method based on dual-viewing angle images. Background Art

[0002] Dislocations are important defects in crystalline materials. Comprehensive characterization of the geometric and crystallographic characteristics of various dislocation configurations in three-dimensional space is of great significance for a deep understanding of basic scientific issues related to dislocations. Diffraction contrast imaging technology based on traditional transmission electron microscopy is an important method for characterizing dislocation morphology, but since this technology can only obtain a two-dimensional projection image of the dislocation, it is difficult to accurately reflect the spatial structural information of the dislocation.

[0003] At present, researchers have developed a three-dimensional dislocation characterization technology based on series tilting based on transmission electron microscopy. Under stable imaging conditions, this technology continuously collects a series of tilted images of the sample in a large angle range with a certain tilt angle step, and then reconstructs the three-dimensional morphology of the dislocation using a suitable three-dimensional reconstruction algorithm. However, this technology usually requires the collection of dozens to hundreds of images, so it takes a lot of time. In addition, for radiation-sensitive materials, long-term electron beam irradiation during image acquisition may cause changes in the dislocation configuration, thereby obtaining distorted or even erroneous three-dimensional reconstruction results. In summary, the efficiency and flexibility of the three-dimensional dislocation characterization technology based on series tilting still need to be improved. The development of a more efficient and accurate three-dimensional dislocation characterization method has become an urgent need for high spatiotemporal resolution dislocation characterization.

[0004] The three-dimensional characterization method of dislocation based on the principle of stereology can calculate the depth information of the dislocation line using several dislocation images at different viewing angles, which greatly reduces the number of images required and weakens the stringent requirements for dislocation imaging conditions. It has important application potential in the study of the dynamic evolution of dislocation three-dimensional structure. However, the three-dimensional reconstructed image of the dislocation obtained by this method can only reflect the morphological information of the dislocation, and cannot systematically and accurately reveal the characteristics of the crystal structure and spatial orientation of the sample where the dislocation is located, and thus cannot achieve high-precision coupling characterization of the dislocation geometric characteristic parameters and crystallographic characteristic parameters, which largely hinders the accurate understanding of the dislocation characteristics and their behavioral characteristics.

[0005] In summary, there is an urgent need to develop a new three-dimensional dislocation characterization method that can achieve characterization with higher efficiency and accuracy, and at the same time realize three-dimensional quantitative coupling characterization of dislocation geometry and crystallographic characteristic parameters, thereby providing an efficient research tool for basic scientific problems related to dislocations in the field of materials science, especially greatly improving the characterization efficiency of dislocation non-equilibrium structures and dynamic behaviors in crystalline materials. Summary of the invention

[0006] The purpose of the present invention is to provide a dislocation crystallographic three-dimensional characterization method based on dual-viewing images, which can achieve coupled quantitative integrated characterization of dislocation geometric characteristics and crystallographic characteristic parameters with high efficiency and high precision.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A dislocation crystallographic three-dimensional characterization method based on dual-view images, comprising:

[0009] Acquire two dislocation images of the sample through a transmission electron microscope, wherein the dislocation images are respectively obtained when the sample is tilted around a sample tilt axis to different tilt angles, and perform image registration on the two dislocation images;

[0010] Binarization and single-pixel processing are performed on the two registered dislocation images to obtain single-pixel dislocation lines, and a preset coordinate system is constructed. According to the geometric information of the dislocation line, the spatial coordinates and a three-dimensional image of the dislocation line in the preset coordinate system are obtained, wherein the preset coordinate system is a three-dimensional coordinate system established with the sample tilt axis and the axis parallel to the electron beam incident direction as coordinate axes when the transmission electron microscope images the sample;

[0011] The sample is tilted in situ so that any crystal zone axis of the sample is parallel to the incident direction of the electron beam, a tilt parameter is obtained according to the tilt angle of the sample, an original reference orientation parameter and a rotation parameter of the sample in the preset coordinate system are obtained according to the crystallographic orientation information of the crystal zone axis, and a reference orientation parameter of the sample in the preset coordinate system is obtained according to the original reference orientation parameter and the rotation parameter, and a conversion parameter from the preset coordinate system to the crystal coordinate system of the sample is obtained according to the reference orientation parameter and the tilt parameter;

[0012] According to the spatial coordinates of the dislocation line in the preset coordinate system and the conversion parameter, the spatial coordinates of the dislocation line in the crystal coordinate system of the sample and a three-dimensional image are obtained.

[0013] Optionally, two dislocation images of the sample are obtained by a transmission electron microscope, wherein the dislocation images are respectively obtained when the sample is tilted around a sample tilt axis to different tilt angles, including:

[0014] When the sample is tilted around the sample tilt axis to a tilt angle θ1, the transmission electron microscope obtains the diffraction vector g hkl Dislocation images under conditions;

[0015] When the sample is tilted around the sample tilt axis to a tilt angle θ2, the transmission electron microscope obtains the diffraction vector -g hkl Dislocation image under .

[0016] Optionally, performing image registration on the two dislocation images includes:

[0017] Using a filtering algorithm to enhance the two dislocation images;

[0018] Detecting and calibrating feature points in the two enhanced dislocation images;

[0019] A feature matching algorithm is used to align the feature points in the two dislocation images to obtain the two aligned dislocation images.

[0020] Optionally, binarizing and pixelizing the two registered dislocation images to obtain a single-pixel dislocation line includes:

[0021] Using a threshold segmentation algorithm to perform image segmentation processing on the two registered dislocation images to obtain an optimal threshold;

[0022] Binarizing the two dislocation images according to an optimal threshold value to obtain two binary images;

[0023] A continuous curve with a line width of a single pixel is used to fit the geometric center position of the dislocation in the two binary images to obtain a single-pixel dislocation line.

[0024] Optionally, obtaining the spatial coordinates and the three-dimensional image of the dislocation line in the preset coordinate system according to the geometric information of the dislocation line includes:

[0025] The spatial coordinates P (x, y, z) of any point on the dislocation line in the preset coordinate system are calculated using the following method:

[0026]

[0027] Wherein, x1, y1 and x2, y2 are the coordinates of the projection points P1 (x1, y1) and P2 (x2, y2) of the point P on the dislocation line when the sample is tilted around the sample tilt axis to the tilt angles θ1 and θ2, respectively, the OX axis is parallel to the sample tilt axis direction, and the OY axis is perpendicular to the sample tilt axis direction, wherein |θ1|≥|θ2|;

[0028] The line direction of the dislocation segment is determined according to the spatial coordinates, the dislocation segment refers to the line segment between every two points on the dislocation line, and the coordinates of two adjacent points on the dislocation line are sequentially connected by line segments to obtain a three-dimensional image of the dislocation line in the preset coordinate system.

[0029] Optionally, according to the coordinates P of two adjacent points on the dislocation line m (x m ,y m , z m ) and Pn (x n ,y n ,z n )(m < n) can determine the local line direction of the dislocation segment V on the dislocation line as follows: smn In the preset coordinate system:

[0030]

[0031] Optionally, obtaining the tilting parameter according to the tilting angle of the sample includes:

[0032] Calculating the tilting parameter by the following method:

[0033]

[0034] where T represents the tilting parameter of the sample, α represents the tilting angle of the sample around the OX axis, β represents the tilting angle of the sample around the OY axis; the OX axis is parallel to the sample tilting axis direction, and the OY axis is perpendicular to the sample tilting axis direction.

[0035] Optionally, obtaining the original reference orientation parameter and the rotation parameter of the sample in the preset coordinate system according to the crystallographic orientation information of the zone axis, and obtaining the reference orientation parameter of the sample in the preset coordinate system according to the original reference orientation parameter and the rotation parameter includes:

[0036] In-situ tilt the sample so that any zone axis direction vector [u1v1w1] of the sample is parallel to the electron beam incident direction. According to the diffraction vector [h1k1l1] of a certain crystal plane under the zone axis and the diffraction vector [r1s1t1] of the crystal plane perpendicular to the diffraction vector [h1k1l1] of the crystal plane, obtain the original reference orientation parameter of the sample in the preset coordinate system. The original reference orientation parameter G r is expressed as:

[0037]

[0038] where G r represents the original reference orientation parameter, [u1v1w1] represents the direction vector of the zone axis, [h1k1l1] and [r1s1t1] respectively represent the diffraction vectors of two mutually perpendicular crystal planes under the zone axis [u1v1w1], where the * sign represents normalization processing;

[0039] According to the angle between the original reference orientation parameter and the diffraction vector [h1k1l1] and the OX axis obtain the rotation parameter of the original reference orientation parameter. The OX axis is parallel to the sample tilting axis direction. The rotation parameter is expressed as:

[0040]

[0041] The reference orientation parameter G is calculated using the following method: R :

[0042]

[0043] Among them, G R represents the reference orientation parameter, [u2v2w2] represents the calculated direction vector of the crystal zone axis, [h2k2l2] represents the diffraction vector parallel to the sample tilt axis under the [u2v2w2] crystal zone axis; [r2s2t2] represents the diffraction vector perpendicular to the sample tilt axis under the [u2v2w2] crystal zone axis; * indicates normalization.

[0044] Optionally, obtaining a conversion parameter from the preset coordinate system to the crystal coordinate system of the sample according to the reference orientation parameter and the tilt parameter includes:

[0045] The conversion parameters are calculated using the following method:

[0046]

[0047] Among them, G represents the conversion parameter, G R represents the reference orientation parameter, T represents the tilt parameter, G r represents the original reference orientation parameter, Represents the rotation parameter.

[0048] Optionally, the dislocation segment V on the dislocation line cmn The local line directions in the crystal coordinate system are calculated using the following method:

[0049] V cmn =G·V smn ;

[0050] Among them, V cmn represents the local line direction of the dislocation segment on the dislocation line in the crystal coordinate system; G represents the transformation parameter, V smn Indicates the local line direction of the dislocation segment on the dislocation line in the preset coordinate system.

[0051] It can be seen from the above technical scheme that the dislocation crystallographic three-dimensional characterization method based on dual-viewing angle images provided by the present invention has few requirements for dislocation imaging conditions. Compared with the dislocation three-dimensional reconstruction method based on series tilt (such as WBP) and sample crystal coordinate system transformation, the sample imaging condition g=[hkl] is always parallel to the sample tilt axis direction during the series image acquisition process. The present method does not require strict imaging conditions. Through two images (all dislocations are visible), three-dimensional reconstruction of dislocation lines and quantitative analysis in the sample crystal coordinate system can be achieved. It is suitable for samples of all orientations. Only two images at different angles need to be collected to reconstruct the three-dimensional shape of the dislocation. It can greatly shorten the image acquisition time and reduce the number of images required, effectively reduce the damage of the electron beam to the sample, and improve the efficiency of dislocation characterization. At the same time, it uses image registration, binarization and single pixel processing to improve the accuracy of dislocation characterization; through the correlation crystallographic analysis method, the quantitative integrated characterization analysis of the coupling of dislocation geometry and crystallographic characteristic parameters in three-dimensional space is realized, and the geometric space structure and crystallographic information of crystal dislocations are clearly, vividly and accurately displayed. In addition, the conversion from the preset coordinate system based on the dual-view image to the crystal coordinate system of the sample can be achieved by tilting once, which significantly improves the efficiency and accuracy compared with the multiple tilts of the series tilt. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0053] Figure 1 A flow chart of a dislocation crystallographic three-dimensional characterization method based on dual-view images provided in one embodiment of the present invention;

[0054] Figure 2 A schematic diagram of establishing a preset coordinate system in one embodiment of the present invention;

[0055] Figure 3 A schematic diagram of an image in image registration according to an embodiment of the present invention;

[0056] Figure 4 A schematic diagram of an image after being converted into a single pixel according to an embodiment of the present invention;

[0057] Figure 5 for Figure 4 A partial enlarged schematic diagram of

[0058] Figure 6 A three-dimensional reconstructed image of dislocation in the preset coordinate system and the crystal coordinate system of the sample according to an embodiment of the present invention;

[0059] Figure 7 A schematic diagram of obtaining conversion parameters from a preset coordinate system to a sample crystal coordinate system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0060] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0061] Please refer to Figure 1 , Figure 1 A flow chart of a dislocation crystallographic three-dimensional characterization method based on dual-view images provided in one embodiment of the present invention, such as Figure 1 As shown, the dislocation crystallography three-dimensional characterization method based on dual-view images includes the following steps:

[0062] S10: Acquire two dislocation images of the sample through a transmission electron microscope, wherein the dislocation images are respectively obtained when the sample is tilted around a sample tilt axis to different tilt angles, and perform image registration on the two dislocation images.

[0063] Please refer to Figure 2 In a specific embodiment of the present invention, the sample is loaded on a double-tilt sample holder of a transmission electron microscope and placed in the transmission electron microscope, and two dislocation images of the sample tilted to different angles around the sample tilt axis α are obtained by the transmission electron microscope. In order to obtain a clear image that can present the three-dimensional morphology of each dislocation in the sample crystal structure, each dislocation in the two different angle images should maintain a clear and visible contrast. Optionally, the sample diffraction vector is collected separately as g hkl and -g hkl Dislocation image under the condition, at this time the corresponding sample is tilted around the sample tilt axis α to the tilt angle θ1 and the tilt angle θ2.

[0064] In order to obtain accurate spatial coordinates that can present the dislocation characteristics in the sample crystal structure, any one of the two dislocation images at different angles is used as a reference image to ensure accurate spatial registration of the two dislocation images. Optionally, a filtering algorithm can be used to enhance the two dislocation images. The specific filtering algorithm can be median filtering, Gaussian filtering, adaptive filtering, etc. Then, the feature points in the two enhanced dislocation images are automatically or manually detected and calibrated by a computer vision algorithm, including but not limited to using a feature matching algorithm to register the feature points in the two dislocation images to obtain the two registered dislocation images. The specific feature matching algorithm can be SIFT and SUFT, etc. Figure 3 The figure is a schematic diagram of an image in the registration of two dislocation images at different angles according to an embodiment of the present invention. After the image registration is completed, the coordinates of the matching feature points of the two dislocation images are equal in the x direction.

[0065] S11: Binarize and pixelate the two registered dislocation images to obtain a single-pixel dislocation line, construct a preset coordinate system, and obtain the spatial coordinates and a three-dimensional image of the dislocation line in the preset coordinate system based on the geometric information of the dislocation line. The preset coordinate system is a three-dimensional coordinate system established with the sample tilt axis and the axis parallel to the electron beam incident direction as coordinate axes when the transmission electron microscope images the sample.

[0066] In order to obtain accurate spatial coordinates that can present the dislocation characteristics in the sample crystal structure, the single-pixel dislocation line is obtained by fitting the geometric center position of the dislocation image in the image through a continuous curve with a line width of a single pixel. Optionally, the registered image pair can be first thresholded and then binarized, and the two registered dislocation images can be segmented using a threshold segmentation algorithm to obtain the optimal threshold; the two dislocation images are binarized according to the optimal threshold to obtain two binary images; and then the BWMORPH algorithm is used to fit the geometric center position of the dislocation image in the image through a continuous curve with a line width of a single pixel to achieve single-pixel dislocation image and obtain the dislocation line. Please refer to Figure 4 , Figure 4 This is a schematic diagram of an image of a dislocation line obtained by converting a dislocation image into a single pixel in this embodiment.

[0067] By using the right-hand rule, a three-dimensional coordinate system is established with the sample tilt axis and the axis parallel to the electron beam incident direction as the coordinate axes when the transmission electron microscope is imaging the dislocation, where the OZ axis is parallel to the opposite direction of the electron beam incident direction, the OX axis is parallel to the sample tilt axis α axis direction, and the OY axis is perpendicular to the sample tilt axis α axis direction. Please refer to Figure 2 , Figure 2 A schematic diagram of establishing a preset coordinate system in this embodiment is shown.

[0068] Based on the displacement difference corresponding to the single-pixelated dislocation images in two dislocation images, the point coordinates containing the geometric information of the dislocation line in three-dimensional space are calculated in a preset coordinate system. Please refer to Figure 5 , Figure 5 which Figure 4 is the schematic diagram of the local enlarged view of the dislocation line in

[0069]

[0070] . When extracting the point coordinates on the curve, the unified two-dimensional coordinate system takes the upper left corner of the image as the coordinate origin O, OX is the vertically downward direction, and the OY axis is the horizontally rightward direction. At the tilting angle of θ1, a point P1(x1, y1) on the dislocation line, and at the corresponding tilting angle of θ2, a point P2(x2, y2) on the dislocation line (where |θ1|≥|θ2|). Then, according to the geometric relationship during the sample tilting process, the point coordinates of the geometric information of the dislocation line in three-dimensional space are solved, that is, the three-dimensional point coordinates P(x, y, z) of the dislocation line in the preset coordinate system are calculated by using the general-purpose interactive method. Specifically, the general-purpose interactive method is expressed as: Figure 6 , Figure 6 The left figure in m is the three-dimensional reconstruction image of the dislocation in the preset coordinate system in this embodiment. Preferably, according to the coordinates P m (x m , y m , z n ) and P n (x n , y n , z smn ) (m < n) of two adjacent points in sequence on the dislocation line, the local line direction of the dislocation segment (V

[0071]

[0072] ) in the preset coordinate system can be determined as:

[0073] Among them, the tilt parameter refers to the parameter reflecting the tilt angle of the sample around the sample tilt axis; the original reference orientation parameter of the sample in the preset coordinate system refers to the parameter reflecting the arrangement of the crystal coordinate axis of the sample in the preset coordinate system when the sample is tilted so that any crystal band axis of the sample is parallel to the incident direction of the electron beam; the rotation parameter refers to the parameter reflecting the rotation angle of the crystal coordinate axis of the sample on the imaging plane; the conversion parameter from the preset coordinate system to the sample crystal coordinate system reflects the conversion relationship from the preset coordinate system to the sample crystal coordinate system. For example, please refer to Figure 7 , Figure 7 The schematic diagram of the conversion parameters from the preset coordinate system to the sample crystal coordinate system in this embodiment is shown in Figure 1. The sample is tilted by α around the OX axis and β around the OY axis from the initial in-situ condition (i.e., α=0°, β=0°) using a double tilt rod under a transmission electron microscope, so that the electron beam incident direction is completely parallel to the [u1v1w1] crystal zone axis. The tilt parameter T of the sample tilt is expressed as:

[0074]

[0075] Wherein, α represents the angle at which the sample is tilted around the OX axis during the tilting process, and β represents the angle at which the sample is tilted around the OY axis during the tilting process.

[0076] The diffraction vector of a certain crystal plane under the crystal zone axis [u1v1w1] is [h1k1l1]. According to the right-hand rule, the diffraction vector [h1k1l1] and the crystal zone axis [u1v1w1] are cross-producted to obtain the diffraction vector [r1s1t1] of the second crystal plane perpendicular to the crystal plane diffraction vector [h1k1l1] and the crystal zone axis direction vector [u1v1w1]. According to the diffraction vectors [h1k1l1] of the two mutually perpendicular crystal planes under the crystal zone axis and the diffraction vectors [r1s1t1] of the crystal plane and the crystal zone axis direction vector [u1v1w1], the original reference orientation parameter G of the sample in the preset coordinate system is obtained. r , specifically, the original reference orientation parameter G r It is expressed as:

[0077]

[0078] Among them, G r represents the original reference orientation parameter, [u1v1w1] represents the direction vector of the crystal zone axis, [h1k1l1] and [r1s1t1] respectively represent the diffraction vectors of two mutually perpendicular crystal planes under the crystal zone axis [u1v1w1], where the * indicates normalization.

[0079] Please refer to Figure 7 , when the crystal coordinate axis of the sample is on the imaging plane, the angle between the diffraction vector [h1k1l1] and the OX axis parallel to the sample tilt axis is further measured. The original reference orientation parameter G can be converted into r On the imaging plane, the angle of rotation around the crystal axis is Obtain the reference orientation parameter G of the sample in the preset coordinate system R , specifically, the reference orientation parameter G R It is expressed as:

[0080]

[0081] Among them, G R represents the reference orientation parameter, [u2v2w2] represents the calculated direction vector of the crystal zone axis, [h2k2l2] represents the diffraction vector parallel to the sample tilt axis under the [u2v2w2] crystal zone axis; [r2s2t2] represents the diffraction vector perpendicular to the sample tilt axis under the [u2v2w2] crystal zone axis; * indicates normalization.

[0082] The conversion parameter from the preset coordinate system to the sample crystal coordinate system is obtained according to the tilt parameter and the reference orientation parameter.

[0083] Specifically, the conversion parameter can be obtained according to the following formula:

[0084]

[0085] Among them, G represents the conversion parameter, G R represents the reference orientation parameter, T represents the tilt parameter, G r represents the original reference orientation parameter, Represents the rotation parameter.

[0086] S13: According to the spatial coordinates and three-dimensional image of the dislocation line in the preset coordinate system and the conversion parameter, the spatial coordinates and three-dimensional image of the dislocation line in the crystal coordinate system of the sample are obtained.

[0087] According to the obtained conversion parameters from the preset coordinate system to the crystal coordinate system of the sample, the spatial coordinates of the dislocation calculated above in the preset coordinate system are converted to the crystal coordinate system of the sample, thereby obtaining the spatial coordinates of the dislocation in the crystal coordinate system of the sample containing the dislocation geometric information, and further based on the spatial coordinates of the dislocation in the crystal coordinate system obtained by conversion, the line direction of the dislocation segment is determined and the coordinates of two adjacent points are connected in sequence with line segments to obtain a three-dimensional image of the dislocation.

[0088] Exemplarily, according to step S12, the conversion relationship between the preset coordinate system and the sample crystal coordinate system can be calculated, and the dislocation segment (V smn ) is converted into the line direction of the sample crystal coordinate system (V cmn), expressed as:

[0089]

[0090] Furthermore, the dislocation crystallographic three-dimensional characterization method based on dual-view images in this embodiment also includes step S14: obtaining the Burgers vector of the dislocation in the image. Specifically, the Burgers vector of the dislocation can be obtained by the following process, including: obtaining the dislocation images of the sample under multiple different diffraction vectors through the transmission electron microscope, and determining the Burgers vector of the dislocation in combination with the invisibility of the dislocation in the dislocation image. The invisibility criterion of the dislocation is expressed as g·b=0, g represents the diffraction vector, and b represents the Burgers vector of the dislocation.

[0091] In a specific embodiment, three-dimensional characterization of dislocations in an Al-Cu-Mg-Ag alloy is taken as an example for explanation.

[0092] 1) The dislocation images at two angles of θ1 = 18° and θ2 = -2° were collected by transmission electron microscopy, and the dislocation image at the angle of θ1 was used as the reference image for image registration (e.g. Figure 3 ) and use the BWMORPH algorithm to single-pixel the registered dislocation image (as shown Figure 4 As shown). By using the right-hand rule, a three-dimensional preset coordinate system is established with the sample tilt axis and the axis parallel to the electron beam incident direction as the coordinate axes when the transmission electron microscope is imaging the dislocation. Based on the single-pixel dislocation image, the spatial coordinates of the dislocation line in the three-dimensional preset coordinate system are further determined by a universal interactive method and a three-dimensional image is constructed (as shown). Figure 6 ).

[0093] 2) Based on the correlation crystallographic analysis, the conversion between the preset coordinate system and the crystal coordinate system of the sample is realized.

[0094] The sample is tilted in situ. When α tilts -31.56° and β tilts -0.59°, it reaches the crystal zone axis

[011] . According to the above analysis, the corresponding sample tilt parameters can be calculated by combining formula (3): At the same time, the diffraction vector corresponding to the (11-1) crystal plane under the

[011] crystal zone axis is obtained as [11-1]. The diffraction vector of the crystal plane perpendicular to both

[011] and [11-1] is calculated as [-21-1] by cross product. According to the above analysis and formula (4), the corresponding sample original reference orientation parameter is determined: In the imaging plane, measure the angle between the diffraction vector [11-1] and the OX axis parallel to the sample tilt axis. is 30°, according to the above analysis, the corresponding rotation parameters can be determined Combined with formula (5), determine the reference orientation parameter of the sample Combined with formula (6), the transformation parameters between the preset coordinate system of the sample and the crystal coordinate system are determined as follows:

[0095] 3) Conversion of dislocation line spatial coordinates and three-dimensional images between the sample's preset coordinate system and the crystal coordinate system.

[0096] like Figure 6 As shown, the spatial coordinates of the dislocation line and the line direction of the dislocation segment in the preset coordinate system of the sample are converted to the crystal coordinate system through formula (7) and a three-dimensional image of the sample in the crystal coordinate system is constructed (such as Figure 6 In materials science, the dislocation reconstruction images are arranged regularly in the crystal system, which can be seen in the reconstruction image of this embodiment, which also proves that this method is accurate and reliable.

[0097] The dislocation crystallographic three-dimensional characterization method based on dual-view images in this embodiment can comprehensively, accurately and quantitatively couple characterize many geometric parameters and crystallographic parameters of dislocations in the crystal coordinate system. In practical applications, many other geometric characteristic information of dislocations can be obtained by calculating the dislocation lines in the three-dimensional image in the preset coordinate system, including but not limited to geometric information such as dislocation length, density, step height, dislocation spacing or curvature radius. Furthermore, according to the conversion relationship from the preset coordinate system to the sample crystal coordinate system and the Burgers vector of the dislocation, the crystallographic characteristic information of the dislocation can be obtained, including but not limited to the dislocation blade screw component, the characteristic plane where the dislocation is located, and the slip system.

[0098] The above is a detailed introduction to the dislocation crystallographic three-dimensional characterization method based on dual-view images provided by the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent application. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A dislocation crystallographic three-dimensional characterization method based on dual-view images, characterized in that: include: Acquire two dislocation images of the sample through a transmission electron microscope, wherein the dislocation images are respectively obtained when the sample is tilted around a sample tilt axis to different tilt angles, and perform image registration on the two dislocation images; Binarization and single-pixel processing are performed on the two registered dislocation images to obtain single-pixel dislocation lines, and a preset coordinate system is constructed. According to the geometric information of the dislocation line, the spatial coordinates and a three-dimensional image of the dislocation line in the preset coordinate system are obtained, wherein the preset coordinate system is a three-dimensional coordinate system established with the sample tilt axis and the axis parallel to the electron beam incident direction as coordinate axes when the transmission electron microscope images the sample; The sample is tilted in situ so that any crystal zone axis of the sample is parallel to the incident direction of the electron beam, a tilt parameter is obtained according to the tilt angle of the sample, an original reference orientation parameter and a rotation parameter of the sample in the preset coordinate system are obtained according to the crystallographic orientation information of the crystal zone axis, and a reference orientation parameter of the sample in the preset coordinate system is obtained according to the original reference orientation parameter and the rotation parameter, and a conversion parameter from the preset coordinate system to the crystal coordinate system of the sample is obtained according to the reference orientation parameter and the tilt parameter; According to the spatial coordinates of the dislocation line in the preset coordinate system and the conversion parameter, the spatial coordinates of the dislocation line in the crystal coordinate system of the sample and a three-dimensional image are obtained.

2. The dislocation crystallographic three-dimensional characterization method based on dual-view images according to claim 1, characterized in that: Two dislocation images of the sample are obtained by transmission electron microscopy, wherein the dislocation images are obtained when the sample is tilted around the sample tilt axis to different tilt angles, including: When the sample is tilted around the sample tilt axis to a tilt angle θ1, the transmission electron microscope obtains the diffraction vector g hkl Dislocation images under conditions; When the sample is tilted around the sample tilt axis to a tilt angle θ2, the transmission electron microscope obtains the diffraction vector -g hkl Dislocation image under .

3. The dislocation crystallographic three-dimensional characterization method based on dual-view images according to claim 1, characterized in that: Performing image registration on the two dislocation images includes: Using a filtering algorithm to enhance the two dislocation images; Detecting and calibrating feature points in the two enhanced dislocation images; A feature matching algorithm is used to align the feature points in the two dislocation images to obtain the two aligned dislocation images.

4. The dislocation crystallographic three-dimensional characterization method based on dual-view images according to claim 1, characterized in that: The two registered dislocation images are binarized and pixelated to obtain a single-pixel dislocation line, including: Using a threshold segmentation algorithm to perform image segmentation processing on the two registered dislocation images to obtain an optimal threshold; Binarizing the two dislocation images according to an optimal threshold value to obtain two binary images; A continuous curve with a line width of a single pixel is used to fit the geometric center position of the dislocation in the two binary images to obtain a single-pixel dislocation line.

5. The dislocation crystallographic three-dimensional characterization method based on dual-view images according to claim 1, characterized in that: Acquiring the spatial coordinates and the three-dimensional image of the dislocation line in the preset coordinate system according to the geometric information of the dislocation line includes: The spatial coordinates P (x, y, z) of any point on the dislocation line in the preset coordinate system are calculated using the following method: Wherein, x1, y1 and x2, y2 are the coordinates of the projection points P1 (x1, y1) and P2 (x2, y2) of the point P on the dislocation line when the sample is tilted around the sample tilt axis to the tilt angles θ1 and θ2, respectively, the OX axis is parallel to the sample tilt axis direction, and the OY axis is perpendicular to the sample tilt axis direction, wherein |θ1|≥|θ2|; The line direction of the dislocation segment is determined according to the spatial coordinates, the dislocation segment refers to the line segment between every two points on the dislocation line, and the coordinates of two adjacent points on the dislocation line are sequentially connected by line segments to obtain a three-dimensional image of the dislocation line in the preset coordinate system.

6. The dislocation crystallographic three-dimensional characterization method based on dual-viewing images according to claim 5, characterized in that: Determining the line direction of the dislocation segment according to the spatial coordinates includes: According to the coordinates P of two adjacent points in sequence on the dislocation line m (x m , y m , z m ) and P n (x n , y n , z n )(m < n), determine that the local line direction of the dislocation segment V smn on the preset coordinate system is:

7. The dislocation crystallographic three-dimensional characterization method based on dual-view images according to any one of claims 1 to 6, characterized in that: Obtaining a tilt parameter according to the tilt angle of the sample includes: The tilt parameters are calculated using the following method: Wherein, T represents the sample tilt parameter, α represents the tilt angle of the sample around the OX axis, and β represents the tilt angle of the sample around the OY axis; the OX axis is parallel to the sample tilt axis direction, and the OY axis is perpendicular to the sample tilt axis direction.

8. The dislocation crystallographic three-dimensional characterization method based on dual-view images according to any one of claims 1 to 6, characterized in that: Obtaining original reference orientation parameters and rotation parameters of the sample in the preset coordinate system according to the crystallographic orientation information of the crystal zone axis, and obtaining reference orientation parameters of the sample in the preset coordinate system according to the original reference orientation parameters and the rotation parameters, including: The sample is tilted in situ so that any crystal band axis direction vector [u1v1w1] of the sample is parallel to the incident direction of the electron beam, and the original reference orientation parameter of the sample in the preset coordinate system is obtained according to the diffraction vector [h1k1l1] of a crystal plane under the crystal band axis and the diffraction vector [r1s1t1] of the crystal plane perpendicular to the diffraction vector [h1k1l1] of the crystal plane. The original reference orientation parameter G r It is expressed as: Among them, G r represents the original reference orientation parameter, [u1v1w1] represents the direction vector of the crystal zone axis, [h1k1l1] and [r1s1t1] represent the diffraction vectors of two mutually perpendicular crystal planes under the crystal zone axis [u1v1w1], respectively, where the * sign indicates normalization; According to the original reference orientation parameter and the angle between the diffraction vector [h1k1l1] and the OX axis Obtain the rotation parameters of the original reference orientation parameters, the OX axis is parallel to the sample tilt axis direction, and the rotation parameters It is expressed as: The reference orientation parameter G is calculated using the following method: R : Among them, G R represents the reference orientation parameter, [u2v2w2] represents the calculated direction vector of the crystal zone axis, [h2k2l2] represents the diffraction vector parallel to the sample tilt axis under the [u2v2w2] crystal zone axis; [r2s2t2] represents the diffraction vector perpendicular to the sample tilt axis under the [u2v2w2] crystal zone axis; * indicates normalization.

9. The dislocation crystallographic three-dimensional characterization method based on dual-view images according to claim 8, characterized in that: Obtaining a conversion parameter from the preset coordinate system to the crystal coordinate system of the sample according to the reference orientation parameter and the tilt parameter, comprising: The conversion parameters are calculated using the following method: Among them, G represents the conversion parameter, G R represents the reference orientation parameter, T represents the tilt parameter, G r represents the original reference orientation parameter, Represents the rotation parameter.

10. The dislocation crystallographic three-dimensional characterization method based on dual-view images according to claim 9, characterized in that: The dislocation segment V on the dislocation line cmn The local line directions in the crystal coordinate system are calculated using the following method: V cmn =G·V smn ; Among them, V cmn represents the local line direction of the dislocation segment on the dislocation line in the crystal coordinate system; G represents the transformation parameter, V smn Indicates the local line direction of the dislocation segment on the dislocation line in the preset coordinate system.

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