Transmission electron microscope analysis method for interaction of nano precipitated phase and dislocation in alloy

Abstract

The invention discloses a transmission electron microscope analysis method for interaction of a nano precipitated phase and dislocation in an alloy, and belongs to the technical field of alloy analysis. According to the method, the target alloy is analyzed through the steps of sample preparation, component analysis, dislocation imaging, image registration and overlay analysis, collaborative characterization of components, morphology and distribution of the nano precipitated phase and interaction behaviors of the nano precipitated phase and dislocation in the same view field is achieved, and the method has high spatial resolution and component sensitivity; and the contrast of the dislocation image is optimized, so that the interaction between the nano precipitated phase and the dislocation structure is visualized, and the technical problems that the nano precipitated phase and the dislocation are difficult to clearly display at the same time and the spatial relationship of the interaction between the nano precipitated phase and the dislocation cannot be intuitively revealed in a single imaging mode are solved. The analysis method is easy to operate, clear in step, good in repeatability, convenient to popularize in a laboratory, high in universality and suitable for analysis of various precipitation strengthened alloys.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of alloy analysis, and in particular to a transmission electron microscope analysis method for interaction between nano precipitates and dislocations in an alloy. BACKGROUND

[0002] Alloy materials are widely used in key industrial fields such as aerospace, energy equipment, and transportation. Their mechanical properties, such as strength, toughness, and creep resistance, are often significantly affected by second-phase particles in the microstructure, especially nano-scale precipitates. Nano precipitates play a key role in regulating the plastic deformation, work hardening, and dynamic recrystallization of alloys by hindering dislocation movement and changing the local stress field. Therefore, in-depth study of the interaction mechanism between nano precipitates and dislocations is of great theoretical significance and engineering value for understanding the deformation behavior of alloys and optimizing material design and process.

[0003] However, due to the size of nano precipitates, which is usually between a few nanometers and tens of nanometers, and the sub-nanometer scale of dislocations, traditional optical microscopes and even ordinary scanning electron microscopes (SEM) cannot directly observe their interaction behavior. Although high-resolution transmission electron microscopy (HRTEM) has atomic-scale resolution, it still faces many challenges in practical applications: first, sample preparation is difficult, and an electron-transparent area that is thin enough and undamaged needs to be obtained; second, the contrast mechanism of dislocations and precipitates is complex, and a single imaging mode often cannot clearly display both; third, the spatial resolution of energy spectrum analysis is limited, making it difficult to accurately characterize the composition distribution of precipitates and their interaction region with dislocations at the nanoscale.

[0004] Currently, some studies have attempted to observe dislocations by combining conventional TEM bright / dark field imaging with diffraction contrast analysis, or to identify second-phase particles with obvious composition differences by HAADF-STEM imaging, but there is still a lack of a systematic, efficient, and repeatable analysis method that can simultaneously characterize the composition, morphology, distribution of nano precipitates, and their interaction behavior with dislocations in the same field of view. Therefore, developing a TEM analysis method that integrates multi-mode imaging and composition analysis is an urgent need in the field of material microcharacterization. SUMMARY

[0005] Therefore, the present application mainly provides a transmission electron microscope analysis method for interaction between nano precipitates and dislocations in an alloy, which solves the technical problem that existing analysis methods cannot simultaneously characterize the composition, morphology, distribution of nano precipitates, and their interaction behavior with dislocations in the same field of view.

[0006] To achieve the above-mentioned purpose, the present application provides a transmission electron microscope analysis method for interaction between nano precipitates and dislocations in an alloy, comprising the following steps: Sample preparation: preparing an electron-transparent thin foil sample of the target alloy; Composition analysis: in scanning transmission electron microscopy mode, using a HAADF detector to scan for a region where a nano precipitate exists, then obtaining an energy spectrum area scan image of the region where the nano precipitate exists, determining the nano precipitate and element composition of the target alloy through the energy spectrum area scan image, determining the matrix element in the target alloy, and determining the enrichment element in the nano precipitate through composition comparison; Dislocation imaging: in transmission electron microscopy mode, obtaining a dislocation structure in the region where the nano precipitate exists under double-beam diffraction conditions in bright field mode and / or dark field mode; Image registration: obtaining a high-angle annular dark field image that can simultaneously observe the nano precipitate and the dislocation structure, and obtaining a bright field image and / or a dark field image under the same field of view, and performing spatial registration on the high-angle annular dark field image, the bright field image and / or the dark field image to adjust the clarity of the nano precipitate and the dislocation structure and obtain a corresponding dislocation image; Overlay analysis: assigning pseudo-color to the matrix element and at least one enrichment element in the nano precipitate to form color contrast between the target alloy matrix and the nano precipitate, obtaining a pseudo-color contrast image, performing image overlay on the pseudo-color contrast image and the dislocation image to generate an overlay image, and analyzing the interaction between the nano precipitate and the dislocation based on the overlay image.

[0007] In some embodiments of the present application, the thickness of the electron-transparent thin foil sample is less than or equal to 100 nm.

[0008] In some embodiments of the present application, the target alloy includes a high-entropy alloy, a nickel-based superalloy, an aluminum alloy, or a steel.

[0009] In some embodiments of the present application, the size of the nano precipitate in the target alloy is less than or equal to 5 nm.

[0010] In some embodiments of the present application, in the step of composition analysis, a HAADF detector is used to scan for a region where a nano precipitate exists, and then the position of the nano precipitate is preliminarily identified using Z-contrast difference, and then an energy spectrum area scan image of the region where the nano precipitate exists is obtained.

[0011] In some embodiments of the present application, in the step of image registration, the high-angle annular dark field image, the bright field image and / or the dark field image are registered by image alignment software to obtain the dislocation image.

[0012] In some embodiments of the present application, in the step of superimposition analysis, two or more of the enrichment elements in the nano precipitates are selected, and pseudo colors are assigned to the selected enrichment elements.

[0013] In some embodiments of the present application, after the pseudo color contrast map is superimposed on the dislocation image, transparency adjustment and color fusion are performed to adjust the clarity of the interaction between the nano precipitates and the dislocation structure, thereby generating the superimposed image.

[0014] In some embodiments of the present application, in the step of superimposition analysis, the analysis of the interaction between the nano precipitates and the dislocations includes judging at least one of the behaviors of the dislocations being pinned by the nano precipitates, the dislocations being bent, the dislocations being wrapped around, or the dislocations being sheared in the nano precipitates.

[0015] In some embodiments of the present application, after the step of superimposition analysis, energy spectrum line scanning or point analysis is performed on the interaction region between the nano precipitates and the dislocations in the superimposed image to quantitatively characterize the composition gradient and / or strain field at the interface.

[0016] The beneficial effects that can be achieved by the present application are as follows: The analysis method of the present application can realize the synergistic characterization of the composition, morphology, distribution of the nano precipitates, and the interaction behavior between the nano precipitates and the dislocations in the same field of view, has higher spatial resolution and composition sensitivity, and optimizes the contrast of the dislocation image, so that the interaction between the nano precipitates and the dislocation structure is visualized, and the technical difficulties that a single imaging mode cannot clearly display the nano precipitates and the dislocations and cannot intuitively reveal the spatial relationship of the interaction between them are overcome.

[0017] The analysis method of the present application is simple to operate, clear in steps, and good in repeatability, and is easy to popularize in the laboratory. Moreover, it has strong universality and is suitable for the analysis of various precipitation-strengthened alloys, including but not limited to high-entropy alloys, nickel-based high-temperature alloys, aluminum alloys, steels, etc. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following briefly introduces the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained from the structures shown in these drawings without creative labor.

[0019] Figure 1 The characterization image of the FeNiTiAlCr high-entropy alloy of embodiment 1 of the present application under the HAADF imaging mode; Figure 2The energy spectrum surface scanning diagram of the FeNiTiAlCr high-entropy alloy of the embodiment 1 of the present application, and the dislocation diagram BF-S image and DF-I image after image alignment; Figure 3 The characterization diagram in the superposition analysis step in the embodiment 1 of the present application.

[0020] The implementation, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0021] It should be understood that the specific embodiments described herein are merely illustrative of the present application and do not limit the present application.

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0023] In the present application, the description such as "first", "second" and the like is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In addition, the technical solutions of various embodiments can be combined with each other, but it must be based on the fact that the technical solutions can be realized by those skilled in the art. When the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, and is not within the scope of protection required by the present application.

[0024] The present application provides a transmission electron microscope analysis method for the interaction between nano precipitates and dislocations in an alloy, comprising the following steps: Sample preparation: preparing an electron transparent thin sample of the target alloy; Composition analysis: in the scanning transmission electron microscope mode, using the HAADF detector to scan to find the region where the nano precipitates exist, then acquiring the energy spectrum surface scanning image of the region where the nano precipitates exist, determining the nano precipitates and the element composition of the target alloy through the energy spectrum surface scanning image, determining the matrix elements in the target alloy, and determining the enrichment elements in the nano precipitates through composition comparison; Dislocation imaging: in the transmission electron microscope mode, acquiring the dislocation structure in the region where the nano precipitates exist under the double-beam diffraction condition in the bright field and / or dark field mode; Image registration: a high-angle annular dark-field image capable of simultaneously observing the nano precipitates and dislocation structure is obtained, a bright-field image and / or a dark-field image are obtained under the same field of view, and the high-angle annular dark-field image, the bright-field image and / or the dark-field image are spatially registered to adjust the clarity of the nano precipitates and the dislocation structure and obtain a corresponding dislocation image; Overlay analysis: pseudo-color is given to the base element and at least one of the enrichment elements in the nano precipitates, so that the target alloy base and the nano precipitates form color contrast, and a pseudo-color contrast image is obtained, the pseudo-color contrast image and the dislocation image are superimposed to generate an overlay image, and the interaction between the nano precipitates and the dislocation is analyzed based on the overlay image.

[0025] The analysis method of the present application can realize the synergistic characterization of the composition, morphology, distribution and interaction behavior of the nano precipitates and dislocations under the same field of view, has higher spatial resolution and composition sensitivity, and optimizes the contrast of the dislocation image, so that the interaction between the nano precipitates and the dislocation structure can be visualized, and the technical difficulties that a single imaging mode cannot clearly display the nano precipitates and the dislocation and cannot intuitively reveal the spatial relationship between the two are overcome.

[0026] Moreover, the analysis method of the present application is simple to operate, clear in steps, good in repeatability, easy to promote in the laboratory, and has strong universality and is suitable for the analysis of various precipitation-strengthened alloys, including but not limited to high-entropy alloys, nickel-based superalloys, aluminum alloys, steels, etc.

[0027] In some embodiments, the target alloy is prepared into an electron-transparent thin sheet sample by focused ion beam (FIB) cutting, electrolytic double spraying, ion thinning, etc.

[0028] In some embodiments, the thickness of the electron-transparent thin sheet sample is less than or equal to 100 nm, and the interface between the precipitates and the target alloy base is clear, reducing the preparation damage.

[0029] In some embodiments, the target alloy includes a high-entropy alloy, a nickel-based superalloy, an aluminum alloy, or a steel.

[0030] In some embodiments, the target alloy is a FeNiTiAlCr high-entropy alloy.

[0031] In some embodiments, the target alloy is subjected to plastic deformation before being analyzed for the interaction between the nano precipitates and the dislocation by the analysis method of the present application.

[0032] In some embodiments, the plastic deformation includes at least one of stretching, compression or creep.

[0033] In the step of composition analysis, the scanning mode of HAADF-STEM and the energy spectrum surface scanning are combined to identify the nano precipitates with a size of less than or equal to 5 nm, and thus, in some embodiments, the size of the nano precipitates in the target alloy is less than or equal to 5 nm. It can be understood that the size of less than or equal to 5 nm refers to the average particle size of the nano precipitates.

[0034] In some embodiments, in the step of composition analysis, the HAADF detector is used to scan for the area where the nano precipitates exist, and then the positions of the nano precipitates are preliminarily identified by using the Z-contrast difference, and then the energy spectrum surface scanning image of the area where the nano precipitates exist is obtained.

[0035] In some embodiments, the double-beam diffraction condition is a strong diffraction beam g vector, and by adjusting the sample tilt angle, a certain group of diffraction beams is in a strong excitation state, so that a high-contrast dislocation image is obtained in the bright field (BF) mode and / or the dark field (DF) mode.

[0036] In some embodiments, in the step of dislocation imaging, by tilting the sample stage, multiple different strong diffraction vectors g are tried, and corresponding bright field images and dark field images are collected respectively, so that the morphology of the dislocation can be well observed by comparing the visibility and contrast changes of the dislocation lines under different diffraction conditions.

[0037] In some embodiments, in the step of dislocation imaging, by optimizing the parameters such as the objective lens diaphragm, the beam spot size and the camera length, the dislocation lines are clearly visible, and overexposure or insufficient contrast is avoided.

[0038] In the image registration step, the high-angle annular dark field image (HAADF image) is used to display the composition contrast and highlight the nano precipitates, and the bright field image (BF) and / or the dark field image (DF) is used to display the diffraction contrast and highlight the dislocations. By spatially aligning the above images and adjusting the sharpness, the clear nano precipitates and dislocation structures can be observed.

[0039] Specifically, the high-angle annular dark field image can simultaneously observe the nano precipitates and the dislocation structure, but the dislocation lines are relatively blurred. Therefore, the bright field image (BF) and / or the dark field image (DF) is obtained under the same field of view, and by spatially registering the HAADF image with the BF image and / or the DF image, a dislocation image with clearer nano precipitates and dislocation structures can be obtained. Subsequent superposition analysis of the dislocation image can easily observe the interaction between the nano precipitates and the dislocations.

[0040] In some embodiments, in the image registration step, the images are registered by using image alignment software.

[0041] In some embodiments, the image alignment software includes DigitalMicrograph or GMS.

[0042] wherein DigitalMicrograph is a digital microscopy image acquisition and processing software developed by Gatan Corporation, and GMS is an acronym for Gatan Microscopy Suite®, also a digital microscopy image acquisition and processing software developed by Gatan Corporation.

[0043] In some embodiments, in the image registration step, a feature point-based automatic or semi-automatic registration algorithm is adopted, the feature points including precipitate phase sharp corners, contamination points, which can significantly improve the accuracy and efficiency of multi-source image registration, reduce the error introduced by human operation, and ensure that images from different imaging modes are accurately aligned at a lower pixel.

[0044] In the superposition analysis step, by assigning a pseudo color to the matrix element with the highest content of the target alloy and at least one enriched element in the nano-precipitate phase, a strong color contrast between the target alloy matrix and the nano-precipitate phase is formed, so that the morphology of the nano-precipitate phase can be clearly observed, and then superimposed with the dislocation image obtained by image registration, the clarity can be adjusted to observe the interaction between the nano-precipitate phase and the dislocation.

[0045] In the present application, the matrix element refers to the element with the highest molar percentage content in the target alloy.

[0046] In the present application, the content of the components in the nano-precipitate phase can be compared to select the element with the highest molar percentage content as the enriched element. For example, the target alloy is FeNiTiAlCr high-entropy alloy, and the nano-precipitate phase contains elements Ni, Ti and Cr. The element with the highest molar percentage content is selected as the enriched element, so that a strong color contrast between the matrix element in the target alloy and the nano-precipitate phase can be formed, and the interaction between the nano-precipitate phase and the dislocation can be easily observed.

[0047] In some embodiments, the type of enriched element is one or more, and the elements in the nano-precipitate phase are arranged from low to high in content, and the element with higher content is selected as the enriched element. For example, when there is one enriched element, it corresponds to the element with the highest content in the nano-precipitate phase; when there are two enriched elements, they correspond to the element with the highest content and the element with the second highest content in the nano-precipitate phase; and so on.

[0048] In some embodiments, in the superimposition analysis step, two or more enrichment elements are selected from the nano precipitates, and pseudo colors are assigned to the selected enrichment elements. By selecting at least two enrichment elements, this embodiment can generate a pseudo color contrast map with strong color contrast and rich information dimensions, which not only greatly enhances the visual recognition of the nano precipitate and the matrix boundary, making the morphology and distribution of the precipitate obvious at a glance, but also can intuitively represent the differences between different chemical composition precipitates through unique color combinations, achieving rapid differentiation of the types of the precipitates, and revealing the composition gradient changes inside the precipitates and at the interface.

[0049] In some embodiments, the pseudo color contrast map and the dislocation image are subjected to transparency adjustment and color fusion to generate the superimposed image. By transparency adjustment and color fusion, this embodiment can highlight the clear morphology of the dislocation structure and the composition of the precipitated elements, reveal the spatial position relationship between the dislocations and different chemical composition precipitates, and make the key interaction behaviors such as pinning and bypassing obvious at a glance.

[0050] In some embodiments, in the superimposition analysis step, analyzing the interaction between the nano precipitates and the dislocations includes judging at least one behavior of the dislocations being pinned by the nano precipitates, the dislocations being bent, the dislocations bypassing or shearing the precipitates. This embodiment can observe the complex morphology in the alloy material.

[0051] In some embodiments, the FeNiTiAlCr high-entropy alloy is taken as the target alloy, the molar content of Fe element in the FeNiTiAlCr high-entropy alloy is the highest, the Fe element is taken as the matrix element of the FeNiTiAlCr high-entropy alloy, and if the enrichment elements in the alloy precipitates in the FeNiTiAlCr high-entropy alloy are determined as Ni, Ti and Cr, pseudo colors are assigned to the matrix element Fe and the enrichment elements Ni, Ti and / or Cr. For example, red color is assigned to Fe, green color which forms a sharp contrast with the red color is assigned to the enrichment element Ni, or green color is assigned to the enrichment element Ni, and blue color in the same series of blue-green color is assigned to the other enrichment elements Ti and / or Cr at the same time, so that the high content element Fe of the alloy matrix and the enrichment elements in the alloy precipitates form a sharp color contrast, and the interaction between the alloy precipitates and the dislocation structure can be clearly observed.

[0052] In some embodiments, after the superimposition analysis step, energy spectrum line scanning or point analysis is performed on the interaction region of the nano precipitates and the dislocations in the superimposed image to quantitatively represent the composition gradient and / or strain field at the interface. This embodiment can quantitatively obtain the concentration distribution curve of the elements across the interface, and accurately represent the interdiffusion behavior and composition gradient of the elements at the phase interface.

[0053] The technical solutions of the present application are further described in detail below in combination with specific embodiments. It should be understood that the specific embodiments below are only used to explain the present application and do not limit the present application.

[0054] Embodiment 1 S10, sample preparation: thin slices of FeNiTiAlCr high-entropy alloy are obtained by alkaline thinning in an electrolytic double-spray manner, which are suitable for transmission electron microscope observation.

[0055] S20, component analysis: the thin slice sample is placed in a Thermo Talos electron microscope, the energy spectrum analysis function is turned on, and scanning is performed on the sample in a scanning transmission electron microscope (STEM) mode using a HAADF detector. The existence of a nano precipitate phase is preliminarily found by using Z contrast difference. When a suspected nano precipitate phase area is found, an energy spectrum scanning image of the area is obtained, and the existence of the nano precipitate phase and its element composition are determined by energy spectrum scanning image analysis. The element with the highest molar percentage in the FeNiTiAlCr high-entropy alloy is taken as the matrix element, and the enrichment elements in the nano precipitate phase are determined by component comparison.

[0056] Reference Figure 2 The element composition of the FeNiTiAlCr high-entropy alloy in the energy spectrum scanning image includes Fe, Ni, Ti, Al, and Cr. The Fe element content in the alloy matrix is higher, and Fe is taken as the matrix element. The Ni, Ti, and Cr elements in the nano precipitate phase are obviously enriched, and Ni, Ti, and Cr are taken as the enrichment elements.

[0057] S30, dislocation imaging: the electron microscope is switched to a transmission electron microscope (TEM) mode, and scanning is performed in the area where the nano precipitate phase exists. By using double-beam imaging technology, the incident direction of the electron beam is adjusted so that a certain group of diffraction beams is in a strong excitation state, and parameters such as objective lens diaphragm, beam spot size, and camera length are optimized to ensure that the dislocation line is clearly visible and to avoid excessive exposure or insufficient contrast. The dislocation structure is found in the area where the nano precipitate phase exists through bright field and / or dark field modes, so that the dislocation structure can be clearly imaged on the fluorescent screen or the detector.

[0058] S40, image registration: the magnification of the electron microscope is adjusted to an appropriate magnification that can clearly display the nano precipitate phase and clearly display the dislocation. Then, the high-angle annular dark field (HAADF) imaging mode is turned on.

[0059] Reference Figure 1 , Figure 1For the HAADF image obtained in the HAADF mode, the nanometer precipitate phase and the dislocation image can be observed at the same time. However, in the HAADF imaging mode, the dislocation line and the precipitate phase profile are relatively blurred, and the interaction cannot be clearly presented, but in the double-beam diffraction condition, the high-angle annular dark-field image and the bright-field image and / or the dark-field image are obtained through spatial registration to obtain clear and sharp dislocation images. Referring to Figure 2 , Figure 2 The BF-S image and the DF-I image in the above are dislocation images after image registration, and the clear and sharp dislocation lines can be clearly displayed.

[0060] S50, superposition analysis: in the energy spectrum analysis software, the colors of the nanometer precipitate phase and the FeNiTiAlCr high-entropy alloy matrix in the energy spectrum scanning image are adjusted. Because the Fe content in the FeNiTiAlCr high-entropy alloy is higher, there is Ni, Ti, and Cr enrichment in the nanometer precipitate phase, therefore, pseudo-color is given to Fe and Ni, Ti, and Cr, so that the target alloy matrix and the nanometer precipitate phase form a color contrast, and a pseudo-color contrast image is obtained. Specifically, red color is given to Fe, green color which can form strong contrast with red color is given to Ni, blue color in the same color system as green color is given to Ti which is also an enrichment element, so as to further form strong color contrast with Fe, then the color contrast image and the dislocation image BF-S image and DF-I image in the image registration step are overlapped to obtain a superposition image.

[0061] Referring to Figure 3 , Figure 3 From left to right, respectively: the color contrast image obtained by giving pseudo-color to Fe and Ni; the superposition image obtained by overlapping the color contrast image obtained by giving pseudo-color to Fe and Ni and the BF-S image; and the superposition image obtained by overlapping the color contrast image obtained by giving pseudo-color to Fe, Ni, and Ti and the DF-I image, so that the interaction between the nanometer precipitate phase and the dislocation structure can be observed, such as whether the dislocation is pinned by the nanometer precipitate phase, the bending of the dislocation around the nanometer precipitate phase, and the like.

[0062] S60, save the original image, the energy spectrum data and the superposition image, and perform image processing to enhance the contrast or the signal-to-noise ratio, output an analysis report, including the precipitate phase size statistics, the dislocation density estimation, the interaction type classification and the like results.

[0063] The above is only a preferred embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent flow transformation made by using the content of the specification and the drawings, or direct or indirect application in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A method of transmission electron microscopy analysis of the interaction of nanoscale precipitates with dislocations in an alloy, characterized in that, The method comprises the following steps: Sample preparation: preparing an electron-transparent thin foil sample of the target alloy; Composition analysis: using a HAADF detector to scan for a region where a nano-precipitate exists in a scanning transmission electron microscope mode, then obtaining an energy spectrum area scan image of the region where the nano-precipitate exists, determining the nano-precipitate and element composition of the target alloy through the energy spectrum area scan image, determining the matrix element in the target alloy, and determining the enrichment element in the nano-precipitate through composition comparison; Dislocation imaging: obtaining a dislocation structure in the region where the nano-precipitate exists in a bright field mode and / or a dark field mode under double-beam diffraction conditions in a transmission electron microscope mode; Image registration: obtaining a high-angle annular dark field image that can simultaneously observe the nano-precipitate and the dislocation structure, and obtaining a bright field image and / or a dark field image under the same field of view, and performing spatial registration on the high-angle annular dark field image, the bright field image and / or the dark field image to adjust the clarity of the nano-precipitate and the dislocation structure and obtain a corresponding dislocation image; Superposition analysis: assigning pseudo-color to the matrix element and at least one enrichment element in the nano-precipitate to form color contrast between the target alloy matrix and the nano-precipitate, and obtaining a pseudo-color contrast image, and performing image superposition on the pseudo-color contrast image and the dislocation image to generate a superimposed image, and analyzing the interaction between the nano-precipitate and the dislocation based on the superimposed image.

2. The method of claim 1, wherein the nano-precipitates interact with dislocations in the alloy. The thickness of the electron-transparent thin foil sample is less than or equal to 100 nm.

3. The method of claim 1, wherein the nano-precipitates interact with dislocations in the alloy. The target alloy comprises a high-entropy alloy, a nickel-based superalloy, an aluminum alloy or a steel.

4. The method of claim 1, wherein the nano-precipitates interact with dislocations in the alloy. The size of the nano-precipitate in the target alloy is less than or equal to 5 nm.

5. The method of claim 1, wherein the nano-precipitates interact with dislocations in the alloy. In the composition analysis step, the HAADF detector is used to scan for a region where a nano-precipitate exists, and then the position of the nano-precipitate is preliminarily identified by using Z-contrast difference, and then an energy spectrum area scan image of the region where the nano-precipitate exists is obtained.

6. The method of claim 1, wherein the nano-precipitates interact with dislocations in the alloy. In the image registration step, the high-angle annular dark field image, the bright field image and / or the dark field image are registered by image alignment software to obtain the dislocation image.

7. The method of claim 1, wherein the nano-precipitates interact with dislocations in the alloy. In the superposition analysis step, two or more enrichment elements are selected from the nano-precipitate, and pseudo-color is assigned to the selected enrichment elements.

8. The method of claim 1, wherein the nano-precipitates interact with dislocations in the alloy. After the pseudo-color contrast image and the dislocation image are superimposed, transparency adjustment and color fusion are performed to adjust the clarity of the interaction between the nano-precipitate and the dislocation structure, thereby generating the superimposed image.

9. The method of claim 1, wherein the nano-precipitates interact with dislocations in the alloy. In the superposition analysis step, the analysis of the interaction between the nano-precipitate and the dislocation includes at least one of the behaviors of dislocation pinning by the nano-precipitate, dislocation bending, dislocation wrapping or shearing the precipitate.

10. The method of claim 1, wherein the nano-precipitates interact with dislocations in the alloy. After the superposition analysis step, energy spectrum line scanning or point analysis is performed on the interaction region between the nano-precipitate and the dislocation in the superimposed image to quantitatively characterize the composition gradient and / or strain field at the interface.

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