Atomic scale deformation field two-gradient decoupling method based on geometric phase analysis

Abstract

The invention provides an atomic scale deformation field two-gradient decoupling method based on geometric phase analysis. The method comprises the following steps: (1) obtaining original data after crystal deformation through a high-resolution transmission electron microscope image; (2) performing Fourier transform on the original data to obtain reciprocal space information, selecting diffraction spots in the reciprocal space information of different crystal orientations to perform inverse Fourier transform to obtain phase information of a local lattice, and obtaining an atomic displacement field in a crystal grain based on the phase information; (3) decomposing the atomic displacement field into a first-order affine displacement gradient tensor and a second-order non-affine displacement gradient tensor, and respectively decomposing the first-order affine displacement gradient tensor and the second-order non-affine displacement gradient tensor to obtain deformation components of respective basic localization events; and (4) defining the participation degree of the atomic scale basic localization event, and analyzing the atomic scale physical mechanism of microdefect evolution. The method is reasonable in conception, and can effectively solve the multi-scale problem of regulation and control of macroscopic performance by a current material microscopic evolution mechanism.

Description

Technical Field

[0001] The present invention relates to the technical field of crystal material defect deformation field analysis, and in particular to a two-term gradient decoupling method of atomic scale deformation field based on geometric phase analysis. Background Art

[0002] The macroscopic mechanical properties of crystalline materials are largely affected by the evolution of their microscopic defects. The type, distribution and dynamic behavior of microscopic defects directly determine the response characteristics of the material under the action of external forces. Therefore, in-depth understanding and analysis of the structural evolution of crystalline materials at the micro-nano scale is of great significance for improving material performance and developing new high-performance materials.

[0003] At the micro-nano scale, displacement fields in crystalline materials are caused by tiny changes in the arrangement of atoms. These changes usually manifest as the movement and interaction of microscopic defects such as dislocations, interfaces, and phase boundaries. Accurately measuring and analyzing these displacement fields can reveal the microstructural characteristics of materials and their evolution laws, thus providing a scientific basis for material design.

[0004] Traditional characterization techniques, such as transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM), can provide nanoscale structural information, but how to effectively extract and quantify displacement field information from these images remains a technical challenge. Geometric phase analysis (GPA), as an advanced image processing technology, can extract displacement field information with high precision through Fourier space analysis of HRTEM images. However, the existing GPA technology mainly focuses on the acquisition of displacement fields, and is not perfect for further decomposing and analyzing the components of these displacement fields (such as rotation fields, volume expansion fields, and shear fields). Summary of the invention

[0005] In response to the technical problems existing in the above-mentioned background technology, the present invention proposes an analytical method for decomposing the micro-nanoscale deformation field of crystal materials to solve the current multi-scale problem of the micro-evolution mechanism of materials regulating macroscopic properties, especially the difficulties in analyzing the evolution mechanism of micro-defects, the complexity of atomic motion, and the interaction mechanism of multiple defects.

[0006] In order to solve the above technical problems, the present invention provides a two-term gradient decoupling method of atomic scale deformation field based on geometric phase analysis, which is characterized by mainly comprising the following steps:

[0007] (1) observing a pre-selected material area with a high-resolution transmission electron microscope to obtain a high-resolution transmission electron microscope image, and obtaining raw data after crystal deformation based on the high-resolution transmission electron microscope image;

[0008] (2) Performing Fourier transform on the original data after crystal deformation to obtain reciprocal space information, selecting diffraction spots in the reciprocal space information of different crystal directions for inverse Fourier transform to obtain the phase information of the local lattice, and then calculating the atomic displacement field inside the grain based on the phase information of the local lattice;

[0009] (3) Perform two-term gradient decomposition on the calculated atomic displacement field, decomposing it into a first-order affine displacement gradient tensor containing local affine deformation and a second-order non-affine displacement gradient tensor containing local non-affine deformation, and decompose the first-order affine displacement gradient tensor and the second-order non-affine displacement gradient tensor separately to obtain the deformation components of their respective basic localized events. After superposition of the two terms, the basic localized event components that comprehensively consider local affine deformation and non-affine deformation are obtained;

[0010] (4) Based on the deformation components of the basic localized events obtained, the respective participation degrees of atoms in the motion are defined, and the spatiotemporal motion patterns of atoms during the evolution of material crystal defects are analyzed to determine the atomic-scale physical mechanism of the evolution of microscopic defects.

[0011] The two-term gradient decoupling method of atomic-scale deformation field based on geometric phase analysis, wherein the specific process of step (2) is as follows:

[0012] (2.1) High-resolution transmission electron microscopy images Perform Fourier transform to obtain reciprocal space image

[0013] (2.2) Select different basis vectors in the reciprocal space The diffraction points of the target are masked, and the selected diffraction points are inversely transformed to reconstruct the intensity distribution information as follows:

[0014]

[0015] In the above formula, g1 and g2 are the coordinates of the selected reciprocal space basis vectors, I is the positive space intensity distribution information obtained after inverse Fourier transform, and A g and P g They represent the amplitude and phase of different diffraction points, respectively, and A0 represents the base value of positive spatial intensity;

[0016] (2.3) According to the reconstructed positive spatial intensity distribution information, the phase change information P is obtained. g , and the displacement field that causes the phase periodic change is obtained.

[0017] The two-term gradient decoupling method of atomic-scale deformation field based on geometric phase analysis, wherein the specific process of step (2.2) is:

[0018] (2.2.1) Select the basis vector in the reciprocal space Diffraction points of the target;

[0019] (2.2.2) After mask processing, select specific frequency components and perform power spectrum analysis to select specific peaks to extract periodic information and lattice structure information in the image.

[0020] (2.2.3) The obtained Fourier transform, we get in, and Select Image intensity information after mask processing and inverse Fourier transformation;

[0021] For displacement The phase change is:

[0022] Thus, the correlation formula between displacement and phase information is obtained, that is, the displacement field formula generated by phase change is:

[0023]

[0024] Among them, u in the above formula x 、u y are the horizontal and vertical displacements in the high-resolution transmission electron microscope image, respectively; g 1x , g 1y , g 2x and g 2y Take the basis vectors and The horizontal and vertical coordinates of and They are and The periodic phase variation in direction is a function of the positive spatial coordinates (x,y).

[0025] The two-term gradient decoupling method of atomic-scale deformation field based on geometric phase analysis, wherein the specific process of performing second-order gradient decomposition on the calculated atomic displacement field in step (3) is:

[0026] (3.1) In order to better analyze the relationship between the microscopic displacement field and the structural crystal orientation, the displacement Transform the coordinates to make them parallel Represents the crystal direction and perpendicular to The rectangular coordinate system of

[0027] (3.2) Perform Taylor expansion on the displacement after coordinate transformation, The first-order affine displacement gradient tensor F and the second-order non-affine displacement gradient tensor η are calculated respectively; among which, the first-order affine displacement gradient tensor is expanded as follows: The second-order non-affine displacement gradient tensor is expressed as

[0028] (3.3) For the first-order affine displacement gradient tensor in two-dimensional space, the decomposition of the basic localized deformation event is:

[0029]

[0030] Among them, in the above formula They are the components of three basic localized events, namely, volume expansion, shear and rotation in affine deformation;

[0031] Decomposition of the second-order non-affine displacement gradient tensor in two-dimensional space into elementary localized deformation events:

[0032]

[0033] And in the above formula They are the volume expansion, shear and rotation components in non-affine deformation respectively;

[0034] (3.4) Superimpose the expansion, rotation and shear components of affine deformation and non-affine deformation:

[0035]

[0036] Among them, a in the above formula i is a first-order binomial tensor, where a1 is parallel to the basis vector g1, and the modulus is equal to the interplanar spacing of the plane in the crystal direction; a2 is perpendicular to a1, and the modulus is equal to the interplanar spacing of the plane in the crystal direction perpendicular to a1; and They are the dimensionless expansion, shear and rotation components of the second-order non-affine deformation; D, S and R represent the three basic localized event components of expansion, shear and rotation that comprehensively consider the first-order affine deformation and the second-order non-affine deformation.

[0037] The two-term gradient decoupling method of atomic-scale deformation field based on geometric phase analysis, wherein the participation of volume expansion, shear and rotation in different regions during the atomic motion in step (4) is defined as:

[0038]

[0039] Among them, P D , P S and P RThey represent the degree of participation of atomic expansion, shear and rotation deformation events in the defect evolution process, respectively, and measure the main deformation mode leading to defect evolution;

[0040] By comparing and analyzing the degree of participation of three basic deformation events, namely, volume expansion, shear and rotation, in different stages of defect evolution, the spatial and temporal motion pattern of atoms in the process of defect generation and evolution is obtained, and the physical mechanism of defect evolution is obtained.

[0041] By adopting the above technical solution, the present invention has the following beneficial effects:

[0042] The present invention is well-conceived and can accurately and completely describe local deformation information, helping to deeply understand the microstructure evolution and deformation mechanism of crystal materials. The present invention can effectively solve the multi-scale problem of the micro-evolution mechanism of materials regulating macroscopic performance, especially the challenges of difficult analysis of micro-defect evolution mechanism, complex atomic motion mode and multiple defect interaction mechanism; at the same time, it can solve the multi-scale problem of the micro-evolution mechanism of materials regulating macroscopic performance, especially the challenges of difficult analysis of micro-defect evolution mechanism, complex atomic motion mode and multiple defect interaction mechanism.

[0043] Compared with the prior art, the present invention has the following characteristics and advantages:

[0044] (1) Combined with the macro freezing test, it can analyze the timing of atomic motion at different evolution stages of micro-nano defects and realize cross-scale analysis of material deformation mechanism. Compared with the traditional geometric phase analysis method, its advantage is that it comprehensively considers the affine and non-affine motion of atoms and has more comprehensive motion information;

[0045] (2) The decomposition of the traditional deformation field is mainly aimed at the von Mises strain defined by affine deformation, which will inevitably cause the loss of deformation information and cannot fully describe the motion mode at the microscopic discrete atomic scale to a certain extent. Taking into account the first-order affine deformation and second-order non-affine deformation of atoms, decomposing them into three basic localized deformation events: volume expansion, shear and rotation, and defining the participation degree of the three types of events, we can deeply analyze the dominant mode of atomic motion and the spatiotemporal motion law of atoms during deformation, overcome the limitations of the complex atomic motion during defect evolution, and describe the microscopic defect evolution process in a new way;

[0046] (3) Compared with current atomic-scale analysis methods, such as molecular dynamics simulation, our method is more integrated with experiments, and the analysis of actual deformed specimens is closer to the actual situation. Especially for the mechanism of multiple defects, we can comprehensively consider the complex atomic motion and provide an effective experimental auxiliary means to reveal the atomic-scale deformation mechanism;

[0047] (4) The current deformation decomposition mainly considers affine motion, which results in the loss of deformation information. Our decomposition method also provides new ideas for the decomposition of other deformation fields.

[0048] At the same time, the present invention also has the following advantages:

[0049] (1) Analyze the atomic motion mechanism of micro-defect evolution and reveal the physical mechanism of the formation and evolution of micro-defects;

[0050] (2) The present invention is helpful for material design and optimization and promotes the research and development of new high-performance materials;

[0051] (3) Combined with freezing test, molecular dynamics simulation and other technologies to improve research efficiency;

[0052] (4) The present invention is applicable to deformation analysis of various crystal materials. It is not only of great value in basic research, but also can be used in the fields of micro-nano technology, semiconductor material analysis, composite materials, etc., and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0054] Figure 1 It is a flow chart of the analysis method of the micro-nanoscale deformation field decomposition of the crystal material of the present invention;

[0055] Figure 2 The displacement field principle diagram is extracted for the geometric phase analysis involved in the analysis method for decomposing the micro-nanoscale deformation field of the crystal material of the present invention. DETAILED DESCRIPTION

[0056] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. 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 are within the scope of protection of the present invention.

[0057] The present invention is further explained below in conjunction with specific implementation modes.

[0058] The present embodiment provides an analysis method for decomposing the micro-nanoscale deformation field of a crystal material. The method first obtains the original data of the crystal after deformation through a high-resolution transmission electron microscope image, and performs a Fourier transform on the data to obtain reciprocal space information; then, the diffraction spots of the reciprocal space of different crystal directions are selected for inverse Fourier transform to obtain the phase information of the local lattice, and then the atomic displacement field inside the grain is obtained through geometric phase analysis; then, the calculated atomic displacement field is subjected to two-term gradient decomposition to decompose it into a first-order affine displacement gradient tensor containing local affine deformation and a second-order non-affine displacement gradient tensor containing local non-affine deformation, and the first-order affine displacement gradient tensor and the second-order non-affine displacement gradient tensor are decomposed respectively, and the three basic localized events of bulk expansion, shear and rotation are decoupled from the comprehensive affine and non-affine atomic motions to accurately and completely describe the local deformation information; finally, according to the degree of participation of the three basic localized events of bulk expansion, shear and rotation in the atomic motion, the atomic spatiotemporal motion pattern during the evolution of material crystal defects is analyzed to determine the atomic-scale physical mechanism of the evolution of microscopic defects.

[0059] like Figure 1 As shown, the analysis method for decomposing the micro-nanoscale deformation field of a crystal material of the present invention specifically comprises the following steps:

[0060] S100, select a material area for high-resolution transmission electron microscope observation and obtain a high-resolution transmission electron microscope image

[0061] S200, high resolution transmission electron microscope images The geometric phase analysis is performed to obtain the local lattice displacement field of the transmission area through the phase information change. Geometric phase analysis is performed by reconstructing the phase change caused by atomic displacement through the distortion of the reciprocal space diffraction points in the high-resolution transmission electron microscope image, and inverting it to obtain the atomic displacement; the specific steps are:

[0062] S210, high resolution transmission electron microscope images Perform Fourier transform to obtain reciprocal space image

[0063] S220. Select different basis vectors in reciprocal space The diffraction points of the target are correctly masked, and the selected diffraction points are inversely Fourier transformed to obtain the phase change information Pg of the local lattice, and the intensity distribution information is reconstructed as:

[0064]

[0065] In the above formula, g1 and g2 are the coordinates of the selected reciprocal space basis vectors, I is the positive space intensity distribution information obtained after inverse Fourier transform, and A g and P g They represent the amplitude and phase of different diffraction points, respectively, and A0 represents the base value of positive spatial intensity;

[0066] The specific steps are as follows:

[0067] S221, select the basis vector in the reciprocal space Diffraction points of the target;

[0068] S222, after g1 and g2 are masked, a specific frequency component is selected, and a power spectrum analysis is performed to select a specific peak value and extract the periodic information and lattice structure information in the image.

[0069] S223, the obtained Inverse Fourier transform, get in, and Select Image intensity information after mask processing and inverse Fourier transformation;

[0070] For displacement Phase change:

[0071]

[0072] Thus, the correlation formula between displacement and phase information is obtained:

[0073]

[0074] Among them, u in the above formula x 、u y are the horizontal and vertical displacements in the high-resolution transmission electron microscope image, respectively; g 1x , g 1y , g 2x and g 2y Take the basis vectors and The horizontal and vertical coordinates of and They are and The periodic phase variation in direction is a function of the positive spatial coordinates (x,y).

[0075] S230, according to the reconstructed positive space intensity distribution information, the displacement formula generated by the phase change, that is, the above-mentioned displacement and phase information correlation formula, can be obtained; wherein, the phase information contains the periodicity of the lattice, the original perfect lattice has a consistent periodicity, and the atomic displacement occurs during the defect evolution process, and the periodic local change can be used to reversely calculate the atomic displacement field;

[0076] S300, expand the displacement information along the main crystallographic direction into a two-term gradient model including a first-order displacement gradient and a second-order displacement gradient, and decompose the rotation R under affine and non-affine motion xy , volume expansion D and shear S xy Locally basicize the deformation component of the event; the specific steps are as follows:

[0077] S301, in order to better analyze the relationship between the microscopic displacement field and the structural crystal orientation, the displacement Transform the coordinates to make them parallel Represents the crystal direction and perpendicular to The rectangular coordinate system of

[0078] S302, perform Taylor expansion on the displacement after coordinate transformation, The first-order affine displacement gradient tensor F and the second-order non-affine displacement gradient tensor η are calculated respectively; among which, the first-order affine displacement gradient tensor is expanded as follows: The second-order non-affine displacement gradient tensor is expressed as The two-term gradient model refers to the addition of the first and second order, representing the affine and non-affine terms;

[0079] The general decomposition of the deformation field is mainly aimed at the von Mi ses strain defined by affine deformation, which will inevitably cause the loss of deformation information. To a certain extent, it cannot fully describe the local affine deformation field, especially the motion mode at the micro-discrete atomic scale. Generally speaking, local rotation events (similar to vortex motion) can be represented by linear transformation and are dominated by the affine part, while the bulk expansion and shear motion of atoms are dominated by severe irregular distortion and belong to the non-affine part of the deformation. Therefore, in order to fully describe the local deformation field information and decouple the three basic localized events from it, it is necessary to comprehensively consider the affine and non-affine parts.

[0080] S303, decomposition of the first-order affine displacement gradient tensor basic localized deformation event in two-dimensional space:

[0081]

[0082] Among them, in the above formula They are the components of three basic localized events, namely, volume expansion, shear and rotation in affine deformation;

[0083] Decomposition of the second-order non-affine displacement gradient tensor in two-dimensional space into elementary localized deformation events:

[0084]

[0085] Similarly, the above They are the volume expansion, shear and rotation components in non-affine deformation respectively;

[0086] S304, superimposing the volume expansion, rotation and shear components of the affine deformation and the non-affine deformation:

[0087]

[0088] In the above formula, a i is a first-order binomial tensor, where a1 is parallel to the basis vector g1, and the modulus is equal to the interplanar spacing of the plane in the crystal direction; a2 is perpendicular to a1, and the modulus is equal to the interplanar spacing of the plane in the crystal direction perpendicular to a1; and are the dimensionless second-order non-affine deformation components of volume expansion, shear and rotation; D, S, and R represent the three basic localized event components of volume expansion, shear and rotation that comprehensively consider the first-order affine deformation and the second-order non-affine deformation, respectively. Here, the superscript A represents the affine deformation component, and the superscript N represents the non-affine deformation component. Among them, the affine deformation A is a dimensionless quantity, and the dimension of the non-affine deformation is [L -1 ], taking full account of affine deformation and non-affine deformation, superimposing them requires integrating non-affine variables to unify the dimensions for superposition. Taking volume expansion as an example: the non-affine deformation volume expansion is: It is expressed as the integral of the non-affine deformation field around the atom in the i direction to measure the non-affine deformation of the atom, which is a dimensionless quantity; however, it is simplified to a i / 2 represents the eigenvalue of the integral of the interplanar spacing.

[0089] S400. Define the participation of rotation, volume expansion and shear in the process of atomic motion, and analyze the main spatiotemporal motion modes of atoms in the process of defect evolution; among them, the participation of volume expansion, shear and rotation in different regions during atomic motion is defined as:

[0090]

[0091] Among them, P D , P S and P R They represent the degree of participation of atomic expansion, shear and rotation deformation events in the defect evolution process, respectively, and measure the main deformation mode leading to defect evolution;

[0092] By comparing and analyzing the degree of participation of three basic deformation events, namely, volume expansion, shear and rotation, in different stages of defect evolution, the spatial and temporal motion pattern of atoms in the process of defect generation and evolution is obtained, and the physical mechanism of defect evolution is obtained.

[0093] The present invention has a reasonable concept and can effectively solve the current multi-scale problem of regulating macroscopic properties of materials by microscopic evolution mechanisms, especially the challenges of difficult analysis of microscopic defect evolution mechanisms, complex atomic motion patterns and multiple defect interaction mechanisms.

[0094] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A two-term gradient decoupling method for atomic-scale deformation field based on geometric phase analysis, characterized in that , mainly including the following steps: (1) observing a pre-selected material area with a high-resolution transmission electron microscope to obtain a high-resolution transmission electron microscope image, and obtaining raw data after crystal deformation based on the high-resolution transmission electron microscope image; (2) Performing Fourier transform on the original data after crystal deformation to obtain reciprocal space information, selecting diffraction spots in the reciprocal space information of different crystal directions for inverse Fourier transform to obtain the phase information of the local lattice, and then calculating the atomic displacement field inside the grain based on the phase information of the local lattice; (3) Perform two-term gradient decomposition on the calculated atomic displacement field, decomposing it into a first-order affine displacement gradient tensor containing local affine deformation and a second-order non-affine displacement gradient tensor containing local non-affine deformation, and decompose the first-order affine displacement gradient tensor and the second-order non-affine displacement gradient tensor separately to obtain the deformation components of their respective basic localized events. After superposition of the two terms, the basic localized event components that comprehensively consider local affine deformation and non-affine deformation are obtained; (4) Based on the deformation components of the basic localized events obtained, the respective participation degrees of atoms in the motion are defined, and the spatiotemporal motion patterns of atoms during the evolution of material crystal defects are analyzed to determine the atomic-scale physical mechanism of the evolution of microscopic defects.

2. The two-term gradient decoupling method of atomic scale deformation field based on geometric phase analysis as claimed in claim 1, characterized in that: The specific process of step (2) is as follows: (2.1) High-resolution transmission electron microscopy images Perform Fourier transform to obtain reciprocal space image (2.2) Select different basis vectors in the reciprocal space The diffraction points of the target are masked, and the selected diffraction points are inversely transformed to reconstruct the intensity distribution information as follows: In the above formula, g1 and g2 are the coordinates of the selected reciprocal space basis vectors, I is the positive space intensity distribution information obtained after inverse Fourier transform, and A g and P g They represent the amplitude and phase of different diffraction points, respectively, and A0 represents the base value of positive spatial intensity; (2.3) According to the reconstructed positive spatial intensity distribution information, the phase change information P is obtained. g , and the displacement field that causes the phase periodic change is obtained.

3. The two-term gradient decoupling method of atomic scale deformation field based on geometric phase analysis as claimed in claim 2, characterized in that: The specific process of step (2.2) is as follows: (2.2.1) Select the basis vector in the reciprocal space Diffraction points of the target; (2.2.2) After mask processing, select specific frequency components and perform power spectrum analysis to select specific peaks to extract periodic information and lattice structure information in the image. (2.2.3) The obtained Fourier transform, we get Among them, H g1 ' and H g2 'Select Image intensity information after mask processing and inverse Fourier transformation; For displacement The phase change is: Thus, the correlation formula between displacement and phase information is obtained, that is, the displacement field formula generated by phase change is: Among them, u in the above formula x 、u y are the horizontal and vertical displacements in the high-resolution transmission electron microscope image, respectively; g 1x , g 1y , g 2x and g 2y Take the basis vectors and The horizontal and vertical coordinates of and They are and The periodic phase variation in direction is a function of the positive spatial coordinates (x,y).

4. The two-term gradient decoupling method of atomic scale deformation field based on geometric phase analysis as claimed in claim 1, characterized in that: The specific process of performing second-order gradient decomposition on the calculated atomic displacement field in step (3) is as follows: (3.1) In order to better analyze the relationship between the microscopic displacement field and the structural crystal orientation, the displacement Transform the coordinates to make them parallel Represents the crystal direction and perpendicular to The rectangular coordinate system of (3.2) Perform Taylor expansion on the displacement after coordinate transformation, The first-order affine displacement gradient tensor F and the second-order non-affine displacement gradient tensor η are calculated respectively; among which, the first-order affine displacement gradient tensor is expanded as follows: The second-order non-affine displacement gradient tensor is expressed as (3.3) For the first-order affine displacement gradient tensor in two-dimensional space, the decomposition of the basic localized deformation event is: Among them, in the above formula They are the components of three basic localized events, namely, volume expansion, shear and rotation in affine deformation; Decomposition of the second-order non-affine displacement gradient tensor in two-dimensional space into elementary localized deformation events: And in the above formula They are the volume expansion, shear and rotation components in non-affine deformation respectively; (3.4) Superimpose the expansion, rotation and shear components of affine deformation and non-affine deformation: Among them, a in the above formula i is a first-order binomial tensor, where a1 is parallel to the basis vector g1, and the modulus is equal to the interplanar spacing of the plane in the crystal direction; a2 is perpendicular to a1, and the modulus is equal to the interplanar spacing of the plane in the crystal direction perpendicular to a1; and They are the dimensionless expansion, shear and rotation components of the second-order non-affine deformation; D, S, and R represent the three basic localized event components of expansion, shear and rotation that comprehensively consider the first-order affine deformation and the second-order non-affine deformation.

5. The two-term gradient decoupling method of atomic scale deformation field based on geometric phase analysis as claimed in claim 1, characterized in that: The participation degree of volume expansion, shear and rotation in different regions during the atomic motion in step (4) is defined as: Among them, P D , P S and P R They represent the degree of participation of atomic expansion, shear and rotation deformation events in the defect evolution process, respectively, and measure the main deformation mode leading to defect evolution; By comparing and analyzing the degree of participation of three basic deformation events, namely, volume expansion, shear and rotation, in different stages of defect evolution, the spatial and temporal motion pattern of atoms in the process of defect generation and evolution is obtained, and the physical mechanism of defect evolution is obtained.

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