CN118609715A - Interlayer centering method and device for 3D-EBSD continuous section data - Google Patents

Abstract

The invention relates to an interlayer centering method and equipment for 3D-EBSD continuous section data, wherein the method comprises the following steps: s1, acquiring grain boundaries with a sigma 3 orientation relation between grains at two sides, namely sigma 3 grain boundaries, from reconstructed 3D-EBSD data; s2, performing plane fitting of a three-dimensional space on a sigma 3 grain boundary to obtain a best fit plane; step S3, selecting a potential coherent sigma 3 grain boundary; s4, linearly translating all triangle centroid points forming a sigma 3 crystal boundary in the 3D-EBSD microstructure to obtain an optimal translation distance, and calculating an M _AB value of a potential coherent sigma 3 crystal boundary, wherein the M _AB value is a weighted average value of the minimum included angle between the best fitting surface and the {111}/{111} crystal surface; step S5, when the value of M _AB is minimum, the grain boundary surface of the potential common sigma 3 grain boundary is parallel to the {111}/{111} crystal planes of the grains at two sides as much as possible, so that interlayer centering of the 3D-EBSD continuous section data is realized. Compared with the prior art, the invention has the advantages of realizing the centering of the multilayer continuous 2D-EBSD section, improving the accuracy and the like.

Description

Interlayer centering method and device for 3D-EBSD continuous section data

Technical Field

The invention relates to the field of interlayer centering of microscopic characterization technology, in particular to an interlayer centering method and equipment for 3D-EBSD continuous section data.

Background

The Three-Dimensional electron back scattering diffraction (Three-Dimensional Electron Backscattered Diffraction, 3D-EBSD) technology is a chromatographic characterization method that acquires continuous multi-layer Two-Dimensional (2D) EBSD cross-section data and performs Three-Dimensional reconstruction, and can obtain a Three-Dimensional spatial microstructure of a material containing crystallographic orientation information. To solve the problem of centering between 2D-EBSD sections, there are two common approaches:

The first method is to mark the same position of each layer section when acquiring continuous 2D-EBSD section data, so as to realize interlayer centering of the 2D-EBSD section. Hardness indentation is a common marker. Multiple indentations mark the same area where EBSD data acquisition is then performed, which marks are helpful for the approximate positioning of the 2D-EBSD cross-section position, but both the deformation of the indentations and the instability of the manual operation may lead to micrometer-scale distance deviations in the cross-section position.

The second method is to obtain the position information of the 2D-EBSD section from the local crystallographic orientation difference, and the position information is used for adjusting the position deviation between adjacent laminae to restore the microscopic morphology of the grains in the material. This method calculates the orientation differences between adjacent layer voxels, finds the corresponding position of the 2D-EBSD cross-section that minimizes the average value of the orientation differences, and then iteratively calculates to determine the relative position of each pair of adjacent layers, the translation distance of the 2D-EBSD cross-section being represented by the number of voxels. The centering algorithm is widely applied to three-dimensional microstructure analysis software, but since the algorithm only considers the relative positions of adjacent 2D-EBSD sections and is limited by the EBSD acquisition step length, errors exist between the relative positions of the adjacent 2D-EBSD sections and the actual positions in the material, and the layer-by-layer accumulation of the errors can cause the orientation distortion of the three-dimensional grain boundary surface. This method lacks a reference standard for confirming whether the crystal interface orientation is correct, so that only the topology of the three-dimensional microstructure can be restored, and the face orientation of the grain boundary cannot be accurately restored. For this purpose new solutions need to be designed to optimize the interlayer centering between successive 2D-EBSD sections.

The difference in orientation between the annealed twins of a Face Centered Cubic (FCC) structured metal and its parent crystals is <111>60 °, with the grain boundary plane typically located at the {111}/{111} crystal plane. This is because the {111} planes are the closest packed planes in the FCC structure, and provide the lowest interfacial energy and highest atomic coordination, and such grain boundaries are also referred to as coherent Σ3 grain boundaries. The intersection between the grain boundaries and the 2D-EBSD cross-section is called the trace of the grain boundaries, the trace of the coherent sigma 3 grain boundaries must be parallel to the trace of the {111} crystal plane, and the grain boundaries whose trace is parallel to the trace of the {111} crystal plane are likely to be coherent sigma 3 grain boundaries. The coherent sigma 3 grain boundary has a stable structure and can be primarily identified according to the trace of the coherent sigma 3 grain boundary on the 2D-EBSD section, so that the coherent sigma 3 grain boundary can be used as a reference interface for centering treatment. Other interfaces with fixed crystal planes in the material can also be used as reference interfaces. On the other hand, in reconstructing a three-dimensional grain boundary network using software such as dream.3d, grain boundaries are divided into a large number of triangular elements. The triangular element centroid point of the translational grain boundary can realize the fine adjustment of the grain boundary orientation.

Grain boundaries are key microstructures affecting the mechanical and corrosion resistance properties of the material. The interlayer centering of continuous multilayer 2D-EBSD data is realized to accurately represent the grain boundary surface orientation in the material, which plays an important role in the research of structural characterization, performance analysis and the like of the metal material. Aiming at 3D-EBSD data obtained by a continuous cross-section method, the invention provides a method for carrying out interlayer centering on continuous multilayer 2D-EBSD data by using a coherent sigma 3 grain boundary as a material internal reference interface.

How to realize interlayer centering between precisely continuous 2D-EBSD sections becomes a technical problem to be solved.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide an interlayer centering method and equipment for 3D-EBSD continuous section data.

The aim of the invention can be achieved by the following technical scheme:

According to an aspect of the present invention, there is provided a method of interlayer centering of 3D-EBSD continuous section data for interlayer centering of 3D-EBSD continuous section data containing a coherent Σ3 grain boundary material, the method comprising the steps of:

S1, acquiring grain boundaries with a sigma 3 orientation relation between grains at two sides, namely sigma 3 grain boundaries, from reconstructed 3D-EBSD data;

S2, performing plane fitting of a three-dimensional space on a sigma 3 grain boundary to obtain a best fit plane;

step S3, selecting a potential coherent sigma 3 grain boundary;

S4, linearly translating all triangle centroid points forming a sigma 3 crystal boundary in the 3D-EBSD microstructure to obtain an optimal translation distance, and calculating an M _AB value of a potential coherent sigma 3 crystal boundary, wherein the M _AB value is a weighted average value of the minimum included angles between a best fit plane and {111}/{111} crystal faces of crystal grains at two sides of the crystal boundary;

Step S5, when the value of M _AB is minimum, the grain boundary surface of the potential common sigma 3 grain boundary is parallel to the {111}/{111} crystal planes of the grains at two sides as much as possible, so that interlayer centering of the 3D-EBSD continuous section data is realized.

Preferably, the grain boundary with a sigma 3 orientation relationship between the grains at the two sides is obtained by rotating the grains at the two sides of the grain boundary by 60 degrees around a common <111> crystal axis, specifically: the deviation of the orientation difference rotation axis of the grain boundary from the <111> crystal axis direction is within A DEG, and the orientation difference rotation angle is within 60 DEG + -B deg.

Preferably, the process of obtaining the best fit plane is specifically: the centroid point of all the triangular elements constituting a certain sigma 3 grain boundary or the perpendicular distance from the geometric point capable of representing the three-dimensional space position of the triangular element to a certain fitting plane is defined as dist _i, and when the sum of absolute values of these dist _i values is minimum, the fitting plane is the best fitting plane.

Preferably, the process of selecting the "potential coherent Σ3 grain boundaries" includes:

S11, selecting a sigma 3 grain boundary with a 3D appearance close to a plane from the sigma 3 grain boundaries;

step S12, obtaining the trace line of the intersection between the best fit plane close to the grain boundary of the plane sigma 3 and the 2D-EBSD section of a certain layer;

And S13, calculating the included angles between the traces and {111}/{111} crystal surface traces of grains at two sides of the grain boundary on the 2D-EBSD section, and if the included angles at two sides are smaller than C degrees, considering the grains to be nearly parallel and defining the grain boundary as a 'potential coherent sigma 3 grain boundary'.

More preferably, in the step S11, selecting the Σ3 grain boundary with the 3D morphology close to the plane specifically includes: calculating normalized root mean square error of sigma 3 grain boundaries corresponding to all dist _i values, wherein sigma 3 grain boundaries with normalized root mean square error less than D are defined as sigma 3 grain boundaries close to the plane.

Preferably, said calculating the M _AB value of the "potential coherent Σ3 grain boundary" includes:

S21, calculating all included angles between the best fit plane and {111} crystal faces in crystal grains at two sides of a crystal grain on a certain 2D-EBSD section, and defining that the minimum values of the included angles in the crystal grains at two sides are respectively theta _A and theta _B;

In step S22, the M _AB value of the "potential coherent Σ3 grain boundary" is calculated, and the mathematical expression of the M _AB value is:

Wherein a _i is the area of the ith grain boundary, a _T is the sum of the areas of all "potential coherent Σ3 grain boundaries", n is the number of grain boundaries, W _θA and W _θB are the weighted average of θ _A and θ _B of all "potential coherent Σ3 grain boundaries", respectively, and M _AB is the average of W _θA and W _θB.

Preferably, in the step S4, linearly translating all triangle centroid points constituting the Σ3 grain boundary in the 3D-EBSD microstructure, obtaining the optimal translation distance, and calculating the M _AB value of the "potential coherent Σ3 grain boundary" includes: the translation distances of the topmost triangle centroid point in the 3D-EBSD microstructure in the X-axis direction and the Y-axis direction are respectively defined as delta X and delta Y, and the mathematical expression of the new coordinates of each triangle centroid point after translation is as follows:

X_i＝x_i+K_i·ΔX

Y_i＝y_i+K_i·ΔY

Wherein Z is the height of the 3D-EBSD microstructure, Z _i is the height of the ith triangle centroid point relative to the bottom of the 3D-EBSD microstructure, K _i is the proportionality coefficient of the translation distance of the ith triangle centroid point, X _i and Y _i are the original coordinates of the ith centroid on the X axis and the Y axis respectively, deltaX and DeltaY are the translation distances of the topmost triangle centroid point in the 3D-EBSD microstructure in the X axis direction and the Y axis direction respectively, and X _i and Y _i represent the new coordinates of the Ping Yihou ith triangle centroid point.

More preferably, in step S4, all triangle centroid points constituting the Σ3 grain boundary in the 3D-EBSD microstructure are linearly translated, an optimal translation distance is obtained, and the M _AB value of the "potential coherent Σ3 grain boundary" is calculated, further including continuously changing Δx and Δy values over a range of X-direction and Y-direction lengths n times the 3D-EBSD data volume, and calculating the corresponding M _AB value of the "potential coherent Σ3 grain boundary".

Preferably, the 3D-EBSD data is obtained by a series of successive 2D-EBSD cross-sectional data reconstructions.

According to another aspect of the present invention, there is provided an electronic device comprising a memory and a processor, the memory having stored thereon a computer program, the processor implementing the method when executing the program.

Compared with the prior art, the invention has the following beneficial effects:

According to the invention, the coherent sigma 3 grain boundary which is positioned in the material and has a structure with a special fixed crystal face is selected as a reference interface, the best fit plane and a potential coherent sigma 3 grain boundary are obtained, and the centroid point of a triangular element of the grain boundary is linearly translated, so that the limit that the translation distance of a 2D-EBSD section can only be the integral multiple of the EBSD image acquisition step length in the prior art is overcome, when the weighted average M _AB of the minimum included angle between the best fit plane of the grain boundary and the {111}/{111} crystal face is minimum, the grain boundary plane of the potential coherent sigma 3 grain boundary is parallel to the {111}/{111} crystal face of the crystal grain as much as possible, and thus, the alignment of multi-layer continuous 2D-EBSD section data, namely the interlayer alignment of 3D-EBSD continuous section data is realized, and compared with the existing alignment method between 2D-EBSD sections, the distortion degree of the orientation of the grain boundary surface is greatly reduced, and the accuracy is higher.

Drawings

FIG. 1 is a schematic flow chart of a middle layer centering method in the invention;

FIG. 2 (a) is a schematic view of the front view of the centroid point of the grain boundary triangle and the best-fit plane for the grain boundary in the present invention;

FIG. 2 (b) is a schematic diagram of a side view of a grain boundary triangle centroid point and a grain boundary best fit plane in accordance with the present invention;

FIG. 3 is a schematic diagram showing the comparison of the positions of the triangle centroid points of a plurality of grain boundaries before and after linear translation in the invention;

FIG. 4 (a) is a graph showing the contour relationship between the DeltaX and DeltaY values and the M _AB value in example 2 of the present invention;

FIG. 4 (b) is a graph showing the contour relationship between the DeltaX and DeltaY values and the M _AB value in example 3 of the present invention.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.

Example 1

The present embodiment relates to an interlayer centering method of 3D-EBSD continuous section data for 3D-EBSD data processing and analysis of a plurality of materials containing a coherent sigma 3 grain boundary, as shown in fig. 1, comprising the steps of:

Step S1, a grain boundary (twin boundary) with a sigma 3 orientation relation (namely <111>60 DEG) between grains at two sides is found out from the reconstructed 3D-EBSD data, namely grains at two sides of the grain boundary rotate 60 DEG around a common <111> crystal axis; the method comprises the following steps: the orientation difference rotation axis of the grain boundary deviates from the <111> crystal axis direction by within 8 degrees, and the orientation difference rotation angle range is within 60 degrees plus or minus 12 degrees; i.e. the tolerance value of the grain boundary orientation difference axis and the tolerance value of the orientation difference angle are set to 8 deg. and 12 deg., respectively.

The 3D-EBSD data is reconstructed from a series of consecutive 2D-EBSD cross-sectional data.

Step S2, performing plane fitting of a three-dimensional space on the sigma 3 grain boundary selected in the step S1:

In three-dimensional space, the vertical distance from the centroid point of all the trigonometric elements constituting a certain sigma 3 grain boundary (or other geometric points capable of representing the position of the trigonometric elements in three-dimensional space) to a certain fitting plane is defined as dist _i, and when the sum of absolute values of the dist _i values is minimum, the fitting plane is the best fitting plane.

And S3, selecting a sigma 3 grain boundary with a 3D appearance close to a plane from grain boundaries. Calculating normalized root mean square error (Normalized Root Mean Square Error, NRMSE) for a grain boundary corresponding to all dist _i values according to equation (1):

In the expression, dist _i is a measurement value of the vertical distance between each triangle centroid point in a single grain boundary and the best fit plane, N is the number of triangle centroid points in a single grain boundary, and dist _max and dist _min represent the maximum value and the minimum value of the vertical distance between the triangle centroid points and the best fit plane, respectively.

Step S4, defining the sigma 3 grain boundaries with NRMSE value less than 0.6 in step S2 as sigma 3 grain boundaries close to the plane.

Step S5, selecting a potential coherent sigma 3 grain boundary, which is specifically:

And (3) acquiring traces intersecting the sigma 3 grain boundary close to the plane in the step S4 and the 2D-EBSD section of a certain layer, and calculating the included angles between the traces and the {111}/{111} crystal surface traces of grains on two sides of the grain boundary on the 2D-EBSD section. If the included angles are all <15 °, then the grain boundaries are considered to be nearly parallel, defining the grain boundaries as "potential coherent Σ3 grain boundaries".

And S6, calculating all included angles between the best fit plane of the grain boundary obtained in the step S2 and {111} crystal faces in grains at two sides of the grain boundary on a certain 2D-EBSD section indicated in the step S3.

The minimum values of these included angles in the grains at both sides are defined as θ _A and θ _B, respectively, and the M _AB value of the "potential coherent Σ3 grain boundary" obtained in step S5 is calculated, and the mathematical expression of the M _AB value is:

Wherein A _i is the area of the ith grain boundary, A _T is the sum of the areas of all the 'potential total sigma 3 grain boundaries', n is the number of grain boundaries, W _θA and W _θB are the weighted average values of theta _A and theta _B of all the 'potential total sigma 3 grain boundaries', M _AB is the average value of W _θA and W _θB, and theta _A and theta _B are the minimum values of the angles between the best fit plane and {111} crystal planes in the grains on both sides. For each grain boundary, one crystal grain is selected as the minimum value of the included angle between the best fit plane and the {111} crystal face in the crystal grain, and the other crystal grain is selected as the minimum value of the included angle between the best fit plane and the {111} crystal face in the crystal grain. For a plurality of grain boundaries, respectively taking weighted average values of minimum included angles in grains at two sides, and then taking average values of the two weighted average values to obtain M _AB.

And S7, linearly translating all triangle centroid points of all grain boundaries in the 3D-EBSD microstructure. The translation distances of the topmost triangle centroid point in the 3D-EBSD microstructure in the X-axis direction and the Y-axis direction are defined as Δx and Δy, respectively. The mathematical expression of the new coordinates of each triangle centroid point after translation is as follows:

X_i＝x_i+K_i·ΔX (6)

Y_i＝y_i+K_i·ΔY (7)

Wherein Z is the height of the 3D-EBSD microstructure, Z _i is the height of the ith triangle centroid point relative to the bottom of the 3D-EBSD microstructure, K _i is the proportionality coefficient of the translation distance of the ith triangle centroid point, X _i and Y _i are the original coordinates of the ith centroid on the X axis and the Y axis respectively, deltaX and DeltaY are the translation distances of the topmost triangle centroid point in the 3D-EBSD microstructure in the X axis direction and the Y axis direction respectively, and X _i and Y _i represent the new coordinates of the Ping Yihou ith triangle centroid point.

And S8, obtaining the optimal translation distance and realizing interlayer centering of the 3D-EBSD continuous section data.

The ΔX and ΔY values are continuously changed over a range of X-direction and Y-direction lengths twice the 3D-EBSD data volume, and the corresponding M _AB of the "potential coherent Σ3 grain boundaries" selected in step S5 is calculated. When the value of M _AB is minimum, the grain boundary face of the "potential coherent sigma 3 grain boundary" in step S5 is already parallel to the {111}/{111} crystal face of the crystal grain as much as possible, thereby achieving interlayer centering of the 3D-EBSD continuous section data.

At present, parameters for quantifying whether the 3D-EBSD interlayer alignment is sufficient or not are lacking, but the alignment of the insufficient grain boundary surface is distorted, so the invention proposes M _AB by utilizing the surface alignment of the coherent sigma 3 grain boundary.

Example 2

The embodiment also relates to an interlayer centering method of the 3D-EBSD continuous section data, which comprises the following specific steps:

a1 First, the 316L austenitic stainless steel to be measured is mechanically polished, and a single Vickers hardness indentation is used for preliminary positioning of the EBSD area to be scanned.

A2 A CamScan Apollo thermal field emission scanning electron microscope (FE-SEM) equipped with Oxford Instrument/HKL-EBSD probe was used to acquire the back-scattered electron diffraction patterns (Kikuchi pattern) of each pixel in the scanning area one by one, and the position and crystal information of each pixel was stored in the EBSD data. The method for controlling the polishing thinning amount comprises the following steps: the rotating speed of the polishing machine, the polishing force and the polishing time are controlled. The total acquisition of 101 layers of continuous sections is carried out, the acquisition step length of the EBSD image is 2.5 mu m, the scanning area is 600 mu m multiplied by 600 mu m, the preset step length in the Z-axis direction is 2.5 mu m, and the average step length in the actual Z-axis direction is 2.55 mu m respectively.

A3 A series of acquired EBSD images were imported into dream.3d software, the thickness of the 2D-EBSD cross section was set to an average of 2.55 μm of actual thickness. The 3D-EBSD data is then processed using the corresponding filters as follows: identifying dead pixels, converting crystal orientation data, primarily centering, removing or repairing partial dead pixels, cutting edges, retrieving and reconstructing crystal grains and crystal boundaries, triangulating grain boundaries, smoothing crystal boundaries and the like. Among them, the filter "Align Sections (Misorientation)" is used for the preliminary centering process. After processing the 3D-EBSD data, paraview software visualizes the data.

A4 Extracting three-dimensional space coordinate values of all triangle element centroids in the grain boundaries, establishing a best fit plane of each grain boundary by using a plane fitting mode, and calculating a plane approximation value of each grain boundary.

A5 The conditions for selecting the potential coherent sigma 3 grain boundary in this example are: the orientation difference rotation axis of the grain boundary deviates from the <111> crystal axis direction by within 2 degrees, and the orientation difference rotation angle range is within 60 degrees plus or minus 2 degrees; the value range of the NRMSE value is 0-0.25, and the number of triangular elements forming a single grain boundary is more than 100; included angles of the grain boundary trace and the {111} crystal plane traces on both sides are respectively smaller than 3 degrees. According to the conditions in this step, 71 "potential coherent Σ3 grain boundaries" satisfying the conditions were selected out in total.

A6 In this example, the translation distance of the centroid point of the topmost triangle in the three-dimensional microstructure is not more than 200 μm in both the X-axis and the Y-axis, i.e., the range of values of ΔX and ΔY is-200 μm to 200 μm. Within this range, the M _AB value of the "potential coherent sigma 3 grain boundary" at the optimal centered position is 5.24, the corresponding DeltaX value is 3 μm and DeltaY value is-115 μm. The value of M _AB before carrying out the present invention was 15.94 °. The M _AB value of the method is far lower than that before execution, so that the plane orientation accuracy of the sigma 3 crystal boundary is greatly improved, and interlayer centering is more accurate.

As shown in fig. 2 (a) and fig. 2 (b), it can be seen from the figures that for the grain boundary with a morphology close to the plane, the normal of the best fit plane can represent the plane normal of the grain boundary, and further can represent the plane orientation of the grain boundary in the grains at two sides, so as to provide a calculation basis for counting the included angle between the plane orientation of the 'potential coherent Σ3 grain boundary' and the {111} crystal plane orientation.

FIG. 3 is a graph of position comparisons before and after linear translation of multiple exemplary grain boundaries and local trigonometric centroids. It can be seen that the linear translation does not change the topographical features of the grain boundaries, but only the plane orientation of the grain boundaries, which protects the positional information of the 2D-EBSD data provided by the local crystallographic difference minimization method.

Fig. 4 (a) is a graph showing the contour relationship between Δx and Δy values and M _AB values in the present embodiment. It can be seen that, in a certain translation range, the minimum value exists in the M _AB value, and the minimum value is obviously smaller than the original value, which indicates that after the centering method of the invention is executed, the plane orientation of the coherent sigma 3 crystal boundary in the three-dimensional microstructure is more approximate to the crystal plane orientation of {111}/{111 }.

Example 3

The embodiment also relates to an interlayer centering method of the 3D-EBSD continuous section data, which comprises the following specific steps:

b1 First, the 316L austenitic stainless steel to be measured is mechanically polished, and a single Vickers hardness indentation is used for preliminary positioning of the EBSD area to be scanned.

B2 This example uses a CamScan Apollo thermal field emission scanning electron microscope (FE-SEM) device equipped with Oxford Instrument/HKL-EBSD probe to acquire the back-scattered electron diffraction pattern (Kikuchi pattern) of each pixel point within the scanning area one by one, and stores the position and crystal information of each pixel point in the EBSD data. The method for controlling the polishing thinning amount comprises the following steps: the rotating speed of the polishing machine, the polishing force and the polishing time are controlled. The total acquisition of 101 layers of continuous sections is carried out, the acquisition step length of the EBSD image is 2.5 mu m, the scanning area is 600 mu m multiplied by 600 mu m, the preset step length in the Z-axis direction is 2.5 mu m, and the average step length in the actual Z-axis direction is 2.65 mu m respectively.

B3 A series of acquired EBSD images were imported into dream.3d software, the thickness of the 2D-EBSD cross section was set to 2.65 μm as the average of the actual thickness. The 3D-EBSD data is then processed using the corresponding filters as follows: identifying dead pixels, converting crystal orientation data, primarily centering, removing or repairing partial dead pixels, cutting edges, retrieving and reconstructing crystal grains and crystal boundaries, triangulating grain boundaries, smoothing crystal boundaries and the like. Among them, the filter "Align Sections (Misorientation)" is used for the preliminary centering process. After processing the 3D-EBSD data, paraview software visualizes the data.

B4 Extracting three-dimensional space coordinate values of all triangle element centroids in the grain boundaries, establishing a best fit plane of each grain boundary by using a plane fitting mode, and calculating a plane approximation value of each grain boundary.

B5 The conditions for selecting the potential coherent sigma 3 grain boundary are as follows: the orientation difference rotation axis of the grain boundary deviates from the <111> crystal axis direction by within 2 degrees, and the orientation difference rotation angle range is within 60 degrees plus or minus 2 degrees; the approximate value range of the plane of the grain boundary is 0-0.3, and the number of triangular elements forming a single grain boundary is more than 100; included angles of the grain boundary trace and the {111} crystal plane traces on both sides are respectively smaller than 3 degrees. According to the conditions in this step, 44 "potential coherent Σ3 grain boundaries" satisfying the conditions were taken out in total.

B6 In this example, the translation distance of the centroid point of the topmost triangle in the three-dimensional microstructure is not more than 200 μm in both the X-axis and the Y-axis, i.e., the range of values of ΔX and ΔY is-200 μm to 200 μm. Within this range, the M _AB value of the "potential coherent sigma 3 grain boundary" at the optimum centered position is 7.60, the corresponding DeltaX value is 44 μm and DeltaY value is-62 μm. The value of M _AB before carrying out the present invention was 12.11 °.

Fig. 4 (b) is a graph showing the contour relationship between Δx and Δy values and M _AB values in the present embodiment. It can be seen that, in a certain translation range, the minimum value exists in the M _AB value, and the minimum value is obviously smaller than the original value, which indicates that after the centering method of the invention is executed, the plane orientation of the coherent sigma 3 crystal boundary in the three-dimensional microstructure is more approximate to the crystal plane orientation of {111}/{111 }.

Example 4

The electronic device of the present invention includes a Central Processing Unit (CPU) that can perform various appropriate actions and processes according to computer program instructions stored in a Read Only Memory (ROM) or computer program instructions loaded from a storage unit into a Random Access Memory (RAM). In the RAM, various programs and data required for the operation of the device can also be stored. The CPU, ROM and RAM are connected to each other by a bus. An input/output (I/O) interface is also connected to the bus.

A plurality of components in a device are connected to an I/O interface, comprising: an input unit such as a keyboard, a mouse, etc.; an output unit such as various types of displays, speakers, and the like; a storage unit such as a magnetic disk, an optical disk, or the like; and communication units such as network cards, modems, wireless communication transceivers, and the like. The communication unit allows the device to exchange information/data with other devices via a computer network, such as the internet, and/or various telecommunication networks.

The processing unit performs the respective methods and processes described above, for example, the methods S1 to S8. For example, in some embodiments, methods S1-S8 may be implemented as a computer software program tangibly embodied on a machine-readable medium, such as a storage unit. In some embodiments, part or all of the computer program may be loaded and/or installed onto the device via the ROM and/or the communication unit. When the computer program is loaded into RAM and executed by the CPU, one or more steps of the methods S1 to S8 described above may be performed. Alternatively, in other embodiments, the CPU may be configured to perform methods S1-S8 by any other suitable means (e.g., by means of firmware).

The functions described above herein may be performed, at least in part, by one or more hardware logic components. For example, without limitation, exemplary types of hardware logic components that may be used include: a Field Programmable Gate Array (FPGA), an Application Specific Integrated Circuit (ASIC), an Application Specific Standard Product (ASSP), a system on a chip (SOC), a Complex Programmable Logic Device (CPLD), and the like.

Program code for carrying out methods of the present invention may be written in any combination of one or more programming languages. These program code may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus such that the program code, when executed by the processor or controller, causes the functions/operations specified in the flowchart and/or block diagram to be implemented. The program code may execute entirely on the machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

In the context of the present invention, a machine-readable medium may be a tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. The machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of a machine-readable storage medium would include an electrical connection based on one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

While the invention has been described with reference to certain preferred embodiments, it will be understood by those skilled in the art that various changes and substitutions of equivalents may be made and equivalents will be apparent to those skilled in the art without departing from the scope of the invention. Therefore, the protection scope of the invention is subject to the protection scope of the claims.

Claims (10)

1. An interlayer centering method of 3D-EBSD continuous section data, characterized in that the method is used for interlayer centering of 3D-EBSD continuous section data containing a coherent Σ3 grain boundary material, the method comprising the steps of:

S1, acquiring grain boundaries with a sigma 3 orientation relation between grains at two sides, namely sigma 3 grain boundaries, from reconstructed 3D-EBSD data;

S2, performing plane fitting of a three-dimensional space on a sigma 3 grain boundary to obtain a best fit plane;

step S3, selecting a potential coherent sigma 3 grain boundary;

S4, linearly translating all triangle centroid points forming a sigma 3 crystal boundary in the 3D-EBSD microstructure to obtain an optimal translation distance, and calculating an M _AB value of a potential coherent sigma 3 crystal boundary, wherein the M _AB value is a weighted average value of the minimum included angles between a best fit plane and {111}/{111} crystal faces of crystal grains at two sides of the crystal boundary;

Step S5, when the value of M _AB is minimum, the grain boundary surface of the potential common sigma 3 grain boundary is parallel to the {111}/{111} crystal planes of the grains at two sides as much as possible, so that interlayer centering of the 3D-EBSD continuous section data is realized.

2. The interlayer centering method of 3D-EBSD continuous section data according to claim 1, wherein the grain boundary with Σ3 orientation relationship between the grain grains at both sides is grain boundary both sides rotated by 60 ° around a common <111> crystal axis, specifically: the deviation of the orientation difference rotation axis of the grain boundary from the <111> crystal axis direction is within A DEG, and the orientation difference rotation angle is within 60 DEG + -B deg.

3. The interlayer centering method of 3D-EBSD continuous section data according to claim 1, wherein said process of obtaining a best fit plane is specifically: the centroid point of all the triangular elements constituting a certain sigma 3 grain boundary or the perpendicular distance from the geometric point capable of representing the three-dimensional space position of the triangular element to a certain fitting plane is defined as dist _i, and when the sum of absolute values of these dist _i values is minimum, the fitting plane is the best fitting plane.

4. The method for interlayer centering of 3D-EBSD continuous section data according to claim 1, wherein said selecting "potential coherent Σ3 grain boundaries" comprises:

S11, selecting a sigma 3 grain boundary with a 3D appearance close to a plane from the sigma 3 grain boundaries;

step S12, obtaining the trace line of the intersection between the best fit plane close to the grain boundary of the plane sigma 3 and the 2D-EBSD section of a certain layer;

And S13, calculating the included angles between the traces and {111}/{111} crystal surface traces of grains at two sides of the grain boundary on the 2D-EBSD section, and if the included angles at two sides are smaller than C degrees, considering the grains to be nearly parallel and defining the grain boundary as a 'potential coherent sigma 3 grain boundary'.

5. The interlayer centering method of 3D-EBSD continuous section data according to claim 4, wherein in said step S11, selecting a Σ3 grain boundary with 3D morphology close to a plane is specifically: calculating normalized root mean square error of sigma 3 grain boundaries corresponding to all dist _i values, wherein sigma 3 grain boundaries with normalized root mean square error less than D are defined as sigma 3 grain boundaries close to the plane.

6. The method of interlayer centering of 3D-EBSD continuous section data of claim 1, wherein said calculating the M _AB value of "potential coherent Σ3 grain boundaries" comprises:

S21, calculating all included angles between the best fit plane and {111} crystal faces in crystal grains at two sides of a crystal grain on a certain 2D-EBSD section, and defining that the minimum values of the included angles in the crystal grains at two sides are respectively theta _A and theta _B;

In step S22, the M _AB value of the "potential coherent Σ3 grain boundary" is calculated, and the mathematical expression of the M _AB value is:

Wherein a _i is the area of the ith grain boundary, a _T is the sum of the areas of all "potential coherent Σ3 grain boundaries", n is the number of grain boundaries, W _θA and W _θB are the weighted average of θ _A and θ _B of all "potential coherent Σ3 grain boundaries", respectively, and M _AB is the average of W _θA and W _θB.

7. The method of interlayer centering of 3D-EBSD continuous section data according to claim 1, wherein in said step S4, linearly translating all triangle centroid points constituting Σ3 grain boundaries in the 3D-EBSD microstructure, obtaining the optimal translation distance, and calculating the M _AB value of "potential coherent Σ3 grain boundaries" includes: the translation distances of the topmost triangle centroid point in the 3D-EBSD microstructure in the X-axis direction and the Y-axis direction are respectively defined as delta X and delta Y, and the mathematical expression of the new coordinates of each triangle centroid point after translation is as follows:

X_i＝x_i+K_i·ΔX

Y_i＝y_i+K_i·ΔY

Wherein Z is the height of the 3D-EBSD microstructure, Z _i is the height of the ith triangle centroid point relative to the bottom of the 3D-EBSD microstructure, K _i is the proportionality coefficient of the translation distance of the ith triangle centroid point, X _i and Y _i are the original coordinates of the ith centroid on the X axis and the Y axis respectively, deltaX and DeltaY are the translation distances of the topmost triangle centroid point in the 3D-EBSD microstructure in the X axis direction and the Y axis direction respectively, and X _i and Y _i represent the new coordinates of the Ping Yihou ith triangle centroid point.

8. The interlayer centering method of 3D-EBSD continuous section data according to claim 7, wherein in step S4, linearly translating all triangle centroid points constituting Σ3 grain boundaries in the 3D-EBSD microstructure, obtaining an optimal translation distance, and calculating an M _AB value of "potential coherent Σ3 grain boundaries", further comprising: the ΔX and ΔY values are continuously varied over a range of lengths in the X and Y directions that is n times the 3D-EBSD data volume, and corresponding M _AB values for the "potential coherent sigma 3 grain boundaries" are calculated.

9. The method of interlayer centering of 3D-EBSD serial section data according to claim 1, wherein said 3D-EBSD data is obtained by a series of serial 2D-EBSD serial section data reconstruction.

10. An electronic device comprising a memory and a processor, the memory having stored thereon a computer program, characterized in that the processor, when executing the program, implements the method according to any of claims 1-9.