Single crystal single-pixel data acquisition and analysis method based on neutron time-of-flight technology

Abstract

The application discloses a single-crystal single-pixel data acquisition and analysis method based on a neutron time-of-flight technology, and the method comprises the following steps: preliminarily orienting a single crystal to be measured; performing a TOF diffraction experiment on the single crystal to be measured, and rotating diffraction spots of a crystal face to be measured to a specified position of a detector according to the result of the preliminary orientation; screening target pixels according to single-pixel diffraction data on the detector, obtaining target pixel positions and diffraction spectra of the target pixels; performing fitting processing on the target pixels, obtaining a crystal face spacing of a specific diffraction crystal face of each pixel point, and a half-height width; calculating lattice strain of different target pixels, and drawing a crystal face spacing distribution diagram of a specific crystal face of the target pixels, a lattice strain distribution diagram, and a half-height width distribution diagram; and for a single-crystal high-temperature alloy, a misfit degree distribution diagram can also be drawn. The application can extract microstructure information of different regions in a diffraction volume of a single-crystal material, and has important significance for perfecting single-crystal material design, a preparation and production process, service damage evaluation and improving a service life of the material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of neutron diffraction, and particularly relates to a single-crystal single-pixel data acquisition and analysis method based on neutron time-of-flight (TOF) technology. BACKGROUND

[0002] Neutrons have the advantages of deep penetration and high spatial resolution, and are one of the most ideal high-flux characterization means for bulk materials. Neutron diffraction technology is currently the only advanced non-destructive testing technology that can realize centimeter-level depth grain orientation and lattice information inside materials. The pulsed polychromatic neutron beam based on the time-of-flight (TOF) technology can scan a large number of reciprocal lattice arrangements through continuous wavelengths (during each pulse) and in cooperation with a fixed-angle area detector, so that multiple Bragg reflections of a single crystal can be measured simultaneously and distinguished by the flight time. These technical features make the TOF technology have natural and unique advantages for measuring single-crystal materials.

[0003] The existing single-crystal related researches using the TOF technology use the total diffraction spectrum generated by the superposition of all diffraction beams of a reflection surface to obtain the average lattice information of the material in the neutron diffraction volume. It has been found in existing researches that the single crystals obtained in actual production are not perfect single crystals, and their diffraction spots often deviate from the ideal case, are unevenly distributed in reciprocal space, and have a certain degree of divergence. The unevenly distributed divergent diffraction spots correspond to the diffraction information of different micro regions inside the material, so that new lattice information can be extracted by single-pixel analysis of the diffraction spots, and the unevenness of the microstructure and deformation of the material can be further revealed. SUMMARY

[0004] In view of the deficiencies of the existing method, the purpose of the present application is to provide a single-crystal single-pixel data acquisition and analysis method based on neutron TOF technology, which extracts the microstructure information of different regions in the diffraction volume of a single-crystal material by depth single-pixel analysis of the TOF diffraction information of the single crystal, and reveals the micro unevenness of the material.

[0005] The present application achieves the above-mentioned purpose by the following technical solutions:

[0006] A single-crystal single-pixel data acquisition and analysis method based on neutron time-of-flight technology, comprising the following steps:

[0007] Preliminary orientation of a single crystal to be measured;

[0008] TOF diffraction experiment on the single crystal to be measured, the diffraction spots of the crystal face to be measured are rotated to the specified position of the detector according to the results of the preliminary orientation, and then the neutron diffraction data is started to be acquired;

[0009] Extracting single-pixel diffraction data on the detector, screening target pixels according to the single-pixel diffraction data, and obtaining target pixel positions and diffraction spectra thereof;

[0010] Performing fitting processing on diffraction spectra of all the finally screened target pixels, and obtaining crystal face spacing and half-height width of specific crystal faces of each pixel point;

[0011] Calculating lattice strain of different target pixels, and drawing crystal face spacing distribution graph, lattice strain distribution graph, and half-height width distribution graph of the target pixels.

[0012] Further, the preliminary orientation of the to-be-measured single crystal comprises: using a laboratory X-ray diffraction device equipped with a multi-axis rotating sample stage or a scanning electron microscope equipped with an electron backscattering diffraction system to preliminarily orient the to-be-measured single crystal, and obtaining the orientation of the specified to-be-measured crystal face relative to the single crystal sample coordinate system; if there are multiple to-be-measured crystal faces, the spatial orientations of the multiple to-be-measured crystal faces relative to the single crystal sample coordinate system are determined.

[0013] Further, the orientation accuracy of the preliminary orientation is less than or equal to 5°.

[0014] Further, the TOF diffraction experiment of the to-be-measured single crystal comprises: rotating the diffraction spot of the to-be-measured crystal face to a specified position of the detector according to the result of the preliminary orientation, and then starting to collect sub-diffraction data, which comprises:

[0015] Zeroing the initial coordinates of the six-foot displacement table, and fixing the single crystal sample on the sample table with the six-foot displacement table, so that the normal of the to-be-measured crystal face is located on the angle bisector of the included angle between the central axis of the detector and the incident beam;

[0016] Using the three-axis heavy-duty table located below the six-foot displacement table to move the to-be-measured point to the neutron beam diffraction center coordinates (X0, Y0, Z0);

[0017] Obtaining the initial rotation center coordinates (X2, Y2, Z2) of the six-foot displacement table;

[0018] Calculating the relative difference ΔX=X0-X2, ΔY=Y0-Y2, and ΔZ=Z0-Z2 between the to-be-measured point coordinates (X0, Y0, Z0) and the initial rotation center coordinates (X2, Y2, Z2) of the six-foot displacement table, and setting the rotation center position in the control software of the six-foot displacement table through the difference, to ensure that the rotation center of the six-foot displacement table is located at the to-be-measured point of the sample;

[0019] Turning on the neutron beam, setting a short collection time (such as 2 min), judging the orientation of the single crystal sample through the diffraction spot position on the detector, then adjusting the spatial orientation of the single crystal sample by using the six-foot displacement table and re-collecting diffraction information, until the diffraction spot of the to-be-measured crystal face is rotated to the specified position of the detector;

[0020] Start formal collection of the diffraction data, set a longer collection time (such as 240 min) to ensure that the intensity of the single-pixel data meets the requirements of diffraction spectrum fitting.

[0021] Further, the screening of the target pixels according to the single-pixel diffraction data comprises:

[0022] Obtaining single-pixel raw data of the detector on which the diffraction spot is located, the raw data containing two-dimensional position coordinates of each pixel on the detector and a complete one-dimensional diffraction spectrum corresponding to each pixel, wherein the complete one-dimensional diffraction spectrum includes a crystal face spacing value and a diffraction intensity value;

[0023] Drawing a two-dimensional distribution map of diffraction intensity of all pixels on the detector, the diffraction intensity being a total integral intensity of diffraction intensity Int corresponding to all crystal face spacing values in the neutron waveband coverage;

[0024] According to the two-dimensional distribution map of the total integral intensity, setting an intensity threshold value or directly specifying the coordinate position of the target pixel, so as to determine the coordinate position of the target pixel and extract the diffraction spectrum of the target pixel;

[0025] Fitting the diffraction spectrum of the target pixel with a model function, and judging whether the data quality of each target pixel meets the fitting requirements according to the peak shape of the original data of each target pixel and the fitting variance; the diffraction data of good quality refers to the peak shape being relatively smooth as a whole and the fitting variance being small; therefore, a threshold value of the peak shape smoothness and the fitting variance can be set to determine whether the data meets the fitting requirements, and the threshold value can be selected according to the user's experience;

[0026] If the data quality of each target pixel meets the requirements, extracting the final diffraction spectrum of the target pixel according to the coordinate position of the target pixel;

[0027] If the data quality of a target pixel does not meet the requirements, merging the target pixel and its adjacent pixels and judging again whether the data quality meets the requirements;

[0028] Finally, it is necessary to ensure that the data quality of all target pixels meets the fitting requirements.

[0029] Further, the model function is generally a Pseudo-Voigt function, and other suitable model functions can also be used.

[0030] Further, the target pixel and its adjacent pixels are merged by using a merging mode of m*n merging, where m is equal to n or m is not equal to n; when the target pixel cannot be located at the center of the to-be-merged pixels (for example, 2*2 merging), the center coordinates of the merged pixels can be selected by itself but should be as close to the original target pixel as possible; when the target pixel can be located at the center of the to-be-merged pixels (3*3 merging), the center coordinates of the merged pixels are still the original target pixel coordinates.

[0031] Further, for single crystal superalloys, by fitting and peak separation processing on the diffraction spectrum of the screened target pixel, the lattice constants of the gamma and gamma' phases are calculated by using the obtained interplanar spacing d and crystallographic knowledge, the misfit degree delta of the two phases is calculated according to the lattice constants, and the misfit degree delta distribution graph is drawn.

[0032] Further, according to the analysis result of the single crystal single pixel data obtained by the above method, the microstructure heterogeneity and the inhomogeneity of micro deformation in the production and service process of the single crystal material are analyzed, the internal high-precision orientation information of the material is obtained, and the damage behavior quantitative analysis is carried out; the analysis result of the single crystal single pixel data includes at least one of the following: the interplanar spacing distribution graph of the specific crystal face of the target pixel, the lattice strain distribution graph, the half-height width distribution graph, and the misfit degree delta distribution graph of the single crystal superalloy.

[0033] Compared with the prior art, the beneficial effects brought by the present application are:

[0034] The present application extracts the microstructure diffraction information of different regions inside the single crystal material by analyzing the diffraction signal of the single crystal material under the TOF technology, which can reveal the microstructure heterogeneity and the inhomogeneity of micro deformation in the production and service process of the single crystal material, obtain the internal high-precision orientation information of the material which cannot be realized by conventional characterization and analysis methods, and perform damage behavior quantitative analysis, which has important significance for improving the single crystal material design, preparation process, service damage evaluation and improving the service life of the material. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a single crystal single pixel data acquisition and analysis method flow diagram based on neutron TOF technology provided by an embodiment of the present application;

[0036] Figure 2 is a single crystal orientation result using EBSD technology in an embodiment of the present application;

[0037] Figure 3 is a single crystal test diffraction geometry diagram based on neutron TOF technology in an embodiment of the present application;

[0038] Figure 4is a detector real-time acquisition image when the crystal face diffraction spot of the single crystal high-temperature alloy (100) is located at an ideal position in an embodiment of the present application;

[0039] Figure 5 is a diffraction intensity two-dimensional distribution graph of all pixels on a selected detector module in a single crystal high-temperature alloy in an embodiment of the present application;

[0040] Figure 6 is a merging manner schematic diagram of target pixel adjacent pixel merging in an embodiment of the present application;

[0041] Fig. 7(a) and Fig. 7(b) are respectively a fitting result before and after merging of a target pixel in an embodiment of the present application, wherein Fig. 7(a) is a fitting result without merging, and Fig. 7(b) is a fitting result after 3x3 merging;

[0042] Figure 8 is an intensity distribution graph of all target pixels screened out in an embodiment of the present application;

[0043] Fig. 9(a) and Fig. 9(b) are respectively a crystal face spacing d distribution graph and a full width at half maximum (FWHM) distribution graph of all target pixels in an embodiment of the present application, wherein Fig. 9(a) is a crystal face spacing d distribution graph, and Fig. 9(b) is a full width at half maximum (FWHM) distribution graph;

[0044] Figure 10 is a γ and γ' two-phase mismatch degree distribution graph of all target pixels of a single crystal high-temperature alloy in an embodiment of the present application. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are 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 labor fall within the scope of protection of the present application. The present application will be further described below in combination with the drawings.

[0046] In order to make those skilled in the art better understand the technical scheme of the present application, the technical scheme of the present application will be described below in combination with the drawings. Figures 1 to 3 The present application will be further described in detail.

[0047] The present application provides a single crystal single-pixel data acquisition and analysis method based on neutron TOF technology, and a data acquisition and analysis process is as shown in Figure 1 The present application provides a single crystal single-pixel data acquisition and analysis method based on neutron TOF technology, and a data acquisition and analysis process is as shown in

[0048] S100: Preliminary orientation of the single crystal to be measured by a laboratory X-ray diffraction device (such as an X-ray texture diffractometer or an X-ray single crystal diffractometer) equipped with a multi-axis rotating sample stage or a scanning electron microscope equipped with an Electron Back Scatter Diffraction (EBSD) system.

[0049] S200: TOF diffraction experiment of the single crystal by a spallation neutron source diffraction device equipped with a high-precision six-legged displacement stage. According to the preliminary orientation result of the single crystal in step S100, after the sample is installed, the diffraction spot of the crystal plane to be measured is rotated to the specified position (near the center position) of the detector with a specific orientation in the real space by the high-precision six-legged displacement stage, and then the neutron diffraction data is collected.

[0050] S300: Obtain single-pixel diffraction data on a specific detector from a data acquisition backend system, draw a two-dimensional distribution map of diffraction intensity on all pixels of the detector, filter target pixels by setting an intensity threshold or directly specifying target pixel coordinates, and obtain the position of the target pixel and its diffraction spectrum. Select an appropriate model function, and judge whether the diffraction data quality of each target pixel meets the fitting requirements by the peak shape of the target pixel diffraction spectrum original data and the fitting variance. If the data quality of the target pixel meets the fitting requirements, the single-pixel diffraction spectrum of the target pixel is directly used. If the data quality of the target pixel does not meet the requirements, the target pixel and its adjacent pixels are combined by defining the range of adjacent pixels of the target pixel, and the data quality is judged again. Finally, the diffraction data quality of all target pixels must meet the fitting requirements. The target pixel refers to the target single pixel of interest to be analyzed in the detector.

[0051] S400: Final fitting processing of the diffraction spectrum of the target pixel filtered in step S300 to obtain the interplanar spacing d value, full width at half maximum (FWHM) and the like of the specific diffraction crystal plane.

[0052] S500: Calculate the lattice strain of different target pixels, and draw the diffraction intensity distribution map, interplanar spacing d distribution map, lattice strain distribution map and FWHM distribution map of the filtered target pixels. The formula for calculating the lattice strain is:

[0053]

[0054] wherein, is the measured interplanar spacing of the reference sample (h k l) crystal plane, d (hkl) is the measured interplanar spacing of the other sample (h k l) crystal plane.

[0055] S600: for single crystal superalloy, the lattice constant a of both γ and γ' phases can be obtained by using the interplanar spacing d fitted in step S400, so as to calculate the mismatch δ of both phases, and then draw a mismatch δ distribution map. The calculation formula of δ is:

[0056]

[0057] wherein a γ′ is the lattice constant of γ' phase in single crystal superalloy, and a γ is the lattice constant of γ phase.

[0058] Preferably, in step S100, the single crystal needs to be preliminarily oriented before the neutron diffraction experiment is carried out, which requires obtaining the orientation of the specified measured crystal face (h k l) relative to the single crystal sample coordinate system. If there are multiple measured crystal faces, the spatial orientation of these crystal faces relative to the single crystal sample coordinate system needs to be determined together. The orientation accuracy is best within 5° (less than or equal to 5°).

[0059] Preferably, step S200 includes the following steps:

[0060] S201: Ensure that the initial coordinates X, Y, Z, Rx, Ry, Rz of the hexapod displacement table are zeroed, fix the single crystal sample on the sample table with the hexapod displacement table, and make the normal of the measured (h k l) crystal face of the sample located on the angle bisector of the angle between the center axis of the sample and the incident beam;

[0061] S202: Obtain the sample measured point coordinates (X1, Y1, Z1) by using the high-precision mechanical arm, and move the measured point to the neutron beam diffraction center coordinates (X0, Y0, Z0) by using the X, Y, Z three-axis heavy load table located below the hexapod displacement table;

[0062] S203: Obtain the initial rotation center coordinates (X2, Y2, Z2) of the hexapod displacement table at this time by using the high-precision mechanical arm;

[0063] S204: Calculate the relative difference ΔX = X0-X2, ΔY = Y0-Y2, ΔZ = Z0-Z2 between the sample measured point coordinates (X0, Y0, Z0) and the initial rotation center coordinates (X2, Y2, Z2) of the hexapod displacement table, and set the rotation center position in the control software of the hexapod displacement table by using the difference, to ensure that the rotation center of the hexapod displacement table is located at the sample measured point;

[0064] S205: Turn on the neutron beam, set a relatively short data acquisition time according to the actual situation, and then adjust the spatial orientation of the single crystal sample by using the hexapod displacement table until the diffraction spot of the measured (h k l) crystal face is rotated to the specified position of the detector;

[0065] S206: Set the long data acquisition time of the single crystal sample, and ensure that the intensity of the single pixel data meets the requirements of the diffraction spectrum fitting.

[0066] Preferably, step S300 comprises the following steps:

[0067] S301: Obtain the single-pixel raw data of the diffraction spot on the detector, which mainly includes the following information: the two-dimensional position (X, Y) of the pixel on the detector, the interplanar spacing d value of the diffraction spectrum in the pixel, and the diffraction intensity Int value;

[0068] S302: Draw a two-dimensional distribution map of the diffraction intensity of all pixels on the selected detector, which is the total integrated intensity of all d values covered by the experimental neutron wave band;

[0069] S303: According to the diffraction total integrated intensity distribution map in step S302, set the intensity threshold or directly specify the coordinate position (X, Y) of the target pixel, determine the position coordinates (X, Y) of the target pixel, and extract the diffraction spectrum of these target pixels;

[0070] S304: Use the selected model function to fit the diffraction spectrum of the determined target pixel, and judge whether the data quality of each target pixel meets the fitting requirements according to the original data peak shape and fitting variance of different target pixels. If yes, proceed to step S306, otherwise proceed to step S305;

[0071] S305: Merge the adjacent pixels of the target pixel. Since the d values of the diffraction spectra of each pixel are the same, the intensity Int value can be directly linearly superimposed when merging the pixels. After superposition, step S304 is performed again;

[0072] S306: Extract the target pixel diffraction spectrum that meets the fitting requirements in step S304, i.e. the single-pixel diffraction spectrum or the merged-pixel diffraction spectrum.

[0073] Preferably, the model function used in step S304 is generally a Pseudo-Voigt function, and other suitable model functions can also be used. The formula of the Pseudo-Voigt function is:

[0074]

[0075] Where y is the fitted value of the diffraction intensity, y0 is the background of the diffraction peak, A is the area of the diffraction peak, i.e. the integrated intensity, η is the proportion of the Lorentz function in the Pseudo-Voigt function, x c is the peak position of the diffraction peak, w is the width of the diffraction peak, and x is the horizontal coordinate interplanar spacing d of the diffraction spectrum.

[0076] Preferably, step S400 requires batch processing of the selected target pixels to obtain the d-value and half-width (FWHM) of all target pixels.

[0077] Preferably, step S500 can draw the diffraction intensity distribution map, interplanar spacing d distribution map, and FWHM distribution map of the selected target pixels; if the lattice strain of different target pixels is calculated, a lattice strain distribution map can also be drawn.

[0078] Preferably, in step S600, the single-crystal high-temperature alloy can obtain the two-phase mismatch degree δ of different pixels and draw the mismatch degree δ distribution map. Other alloys such as steel, titanium alloy, aluminum alloy and magnesium alloy cannot obtain this distribution map.

[0079] The technical solution of the present invention will be specifically described below using nickel-based single-crystal superalloys as an example.

[0080] 1. Using a scanning electron microscope equipped with an EBSD system, preliminary orientation of the single-crystal superalloy under test was performed, such as... Figure 2 As shown, the relationship between the test crystal planes (100) and (001) and the sample coordinate system is obtained;

[0081] 2. TOF diffraction experiments on single crystals were conducted using a general-purpose powder diffractometer at the China Spallation Neutron Source. This spectrometer is equipped with a high-precision six-legged displacement stage, which can meet the testing requirements for single crystals. The steps of the TOF diffraction experiment on single crystals include:

[0082] a) Based on the single crystal orientation results in step 1, install the sample, ensuring that the normals of the (100) and (001) crystal planes to be measured are located on the angle bisector of the angle between the detector center and the incident beam. Figure 3 A schematic diagram of the diffraction geometry during sample testing is provided.

[0083] b) Subsequently, by moving the heavy-load stage and setting a new rotation center for the hexapod displacement stage, the neutron beam diffraction center, the sample test point, and the rotation center of the hexapod displacement stage are made to coincide.

[0084] c) Turn on the neutron beam, set the data acquisition time to 2 minutes, and then use a six-legged displacement stage to adjust the spatial orientation of the single crystal sample, rotating the diffraction spots of the (100) and (001) crystal planes to be measured to the center of the detector, such as... Figure 4 As shown;

[0085] d) The final data acquisition time was set to 240 min to ensure that the intensity of single-pixel data met the requirements for diffraction spectrum fitting.

[0086] 3. Extraction Figure 3 Using single-pixel diffraction data from detectors 1 and 2, a two-dimensional distribution map of the diffraction intensity of all pixels on the selected detectors was plotted. This diffraction intensity represents the neutron band used in the experiment. The total integral intensity of the diffraction intensity Int corresponding to all covered d values is shown as Figure 5 The Pseudo-Voigt function is selected as the model function. Since the original data diffraction intensity of the target pixel is low, the fitting quality is poor, the target pixel is merged with adjacent pixels, and the merging method is shown as Figure 6 The fitting maps of the same pixel point before merging and after 3x3 merging are shown in FIG. 7(a) and FIG. 7(b), respectively. The total diffraction intensity threshold is set to 150, the target pixels are screened, the pixel positions and diffraction spectra are obtained, and the intensity distribution diagram of the screened target pixels is shown as Figure 8 The two detectors (detector 1 and detector 2) can obtain information of two orientations at the same time, thereby improving the efficiency, and in other embodiments, only one detector can be used.

[0087] 4. The original diffraction spectrum of the screened target pixel is fitted and peak-separated to obtain the crystal plane spacing d value, full width at half maximum (FWHM), etc. of the (100) crystal plane;

[0088] 5. The lattice strain of different target pixels is calculated, and the crystal plane spacing d distribution diagram, lattice strain distribution diagram, and FWHM distribution diagram of the screened target pixels are drawn. In this example, only the crystal plane spacing d distribution diagram and FWHM distribution diagram of the (100) crystal plane are calculated and drawn, as shown in FIG. 9(a) and FIG. 9(b), respectively.

[0089] 6. For single crystal superalloys, the crystal plane spacing d of the (100) crystal plane can be considered equal to the lattice constant a, so the lattice constants a of the γ and γ' phases can be obtained at the same time, the misfit degree δ of the two phases is calculated, and then the misfit degree δ distribution diagram is drawn, as shown in Figure 10

[0090] In this embodiment, the size of a single pixel of the detector is 4x4 mm, and the distance between the detector and the sample is 2 m. According to the diffraction intensity distribution diagram in step 3, the diffraction spot covers an area of about 30x12 pixels, so the maximum internal misorientation of the single crystal superalloy near the (100) crystal plane is about The crystal plane spacing d distribution diagram, FWHM distribution diagram, and misfit degree δ distribution diagram in steps 5 and 6 show that the misfit degrees of different regions in the single crystal alloy are mostly distributed between -0.3% and -0.2%, and the maximum lattice constant difference between different regions is about ​The value is close to the difference of lattice constants of γ and γ' two phases in the alloy. In addition, the smaller the lattice constant, the larger the FWHM of the (100) plane of the γ' phase, which indicates that the γ' phase lattice constant size and uniformity in different regions of the single crystal alloy during directional solidification due to composition segregation, which may affect the subsequent local micro-mechanical behavior of the alloy during service.

[0091] The specific embodiments of the application disclosed above are intended to help understand the content of the application and to implement the application, those skilled in the art can understand that various replacements, changes and modifications are possible without departing from the spirit and scope of the application. The application should not be limited to the content disclosed in the examples of the specification, the protection scope of the application is defined by the scope of the claims.

Claims

1. A method for acquiring and analyzing single-crystal single-pixel data based on neutron time-of-flight technology, characterized in that, Includes the following steps: Preliminary orientation of the single crystal to be tested; To perform a TOF diffraction experiment on the single crystal under test, the diffraction spots on the crystal plane under test are rotated to the designated position of the detector based on the preliminary orientation results, and then neutron diffraction data are collected. Extract single-pixel diffraction data from the detector, filter target pixels based on the single-pixel diffraction data, and obtain the target pixel position and its diffraction spectrum; The diffraction patterns of all the final selected target pixels are fitted to obtain the interplanar spacing and full width at half maximum (FWHM) of each pixel's specific diffraction plane. Calculate the lattice strain of different target pixels, and plot the interplanar spacing distribution, lattice strain distribution, and full width at half maximum (FWHM) distribution of the target pixels; The step of filtering target pixels based on single-pixel diffraction data includes: Obtain the raw data of a single pixel of the detector where the diffraction spot is located. This raw data includes the two-dimensional position coordinates of each pixel on the detector, as well as the complete one-dimensional diffraction pattern corresponding to each pixel, including the interplanar spacing value and the diffraction intensity value. Plot a two-dimensional distribution of diffraction intensity for all pixels on the detector. This diffraction intensity is the total integral intensity of the diffraction intensity Int corresponding to all interplanar spacing values ​​within the neutron band coverage area. Based on the two-dimensional distribution map of total diffraction intensity, an intensity threshold is set or the coordinate position of the target pixel is directly specified to determine the position coordinates of the target pixel and extract the diffraction spectrum of the target pixel. The diffraction spectrum of the target pixel is fitted using a model function. Based on the peak shape of the original data of different target pixels and the fitting variance, it is determined whether the data quality of each target pixel meets the fitting requirements. If the data quality of each target pixel meets the requirements, the final diffraction pattern of the target pixel is extracted based on the position coordinates of the target pixel. If the data quality of a target pixel does not meet the requirements, the target pixel and its neighboring pixels are merged, and the data quality is checked again to see if it meets the requirements. Ultimately, it is necessary to ensure that the data quality of all target pixels meets the fitting requirements.

2. The method according to claim 1, characterized in that, The preliminary orientation of the single crystal to be tested includes: using a laboratory X-ray diffraction device equipped with a multi-axis rotating sample stage or a scanning electron microscope equipped with an electron backscatter diffraction system to perform preliminary orientation of the single crystal to be tested, and obtaining the orientation of the specified crystal facet to be tested relative to the coordinate system of the single crystal sample; if there are multiple crystal faces to be tested, the spatial orientation of multiple crystal faces to be tested relative to the coordinate system of the single crystal sample is determined together.

3. The method according to claim 2, characterized in that, The initial orientation accuracy is less than or equal to 5°.

4. The method according to claim 1, characterized in that, The TOF diffraction experiment on the single crystal under test involves rotating the diffraction spots of the crystal plane under test to the designated position on the detector based on the preliminary orientation results, and then starting to collect neutron diffraction data, including: Set the initial coordinates of the six-legged displacement stage to zero, fix the single crystal sample on the sample stage with the six-legged displacement stage, and make the normal of the crystal plane to be measured lie on the angle bisector of the angle between the central axis of the detector and the incident beam. The point to be measured is moved to the coordinates (X0, Y0, Z0) of the neutron beam diffraction center using a triaxial heavy-duty stage located below the hexapod displacement stage. Obtain the initial rotation center coordinates (X2, Y2, Z2) of the hexapod displacement stage; Calculate the relative difference between the coordinates of the point to be measured (X0, Y0, Z0) and the initial rotation center coordinates (X2, Y2, Z2) of the hexagonal displacement stage. X = X0 – X2, Y = Y0 – Y2, Z = Z0 - Z2. In the control software of the six-legged displacement stage, the rotation center position is set by this difference to ensure that the rotation center of the six-legged displacement stage is located at the sample test point. Turn on the neutron beam, set a short acquisition time, determine the orientation of the single crystal sample by the position of the diffraction spot on the detector, then use a six-legged displacement stage to adjust the spatial orientation of the single crystal sample and reacquire diffraction information until the diffraction spot of the crystal plane to be tested is rotated to the designated position of the detector. We began formally collecting neutron diffraction data, setting a relatively long acquisition time to ensure that the intensity of single-pixel data met the requirements for diffraction spectrum fitting.

5. The method according to claim 1, characterized in that, The model function is the Pseudo-Voigt function or other suitable model function. The formula for the Pseudo-Voigt function is: in, The values ​​are the fitted calculation values ​​for the diffraction intensity. The background of the diffraction peaks. The diffraction peak area is the integral intensity. The proportion of the Lorentz function in the Pseudo-Voigt function. The peak position of the diffraction peak. The width of the diffraction peak. The horizontal axis of the diffraction pattern is the interplanar spacing. .

6. The method according to claim 1, characterized in that, The method used to merge the target pixel and its neighboring pixels is as follows: Merging, among which equal or Not equal to ; When the target pixel cannot be located at the center of the pixels to be merged, the center coordinates of the merged pixel should be selected automatically, but should be as close as possible to the original target pixel; when the target pixel is located at the center of the pixels to be merged, the center coordinates of the merged pixel are still the coordinates of the original target pixel.

7. The method according to claim 1, characterized in that, For single-crystal high-temperature alloys, the diffraction spectra of the selected target pixels are fitted and peaked, and the obtained interplanar spacing is used as the basis for the analysis. Calculated using crystallographic knowledge and The lattice constants of the two phases are used to calculate the degree of misfit between the two phases. And plot the mismatch degree Distribution map.

8. The method according to claim 7, characterized in that, The mismatch The calculation formula is: in, It is a single-crystal high-temperature alloy The lattice constant of the phase, yes The lattice constant of the phase.

9. The method according to any one of claims 1 to 8, characterized in that, Based on the analysis results of the obtained single-crystal single-pixel data, the microstructural heterogeneity and micro-deformation inhomogeneity during the production and service of single-crystal materials are analyzed, and high-precision orientation information inside the material is obtained, as well as quantitative analysis of damage behavior is performed. The analysis results of the single-crystal single-pixel data include at least one of the following: interplanar spacing distribution map, lattice strain distribution map, full width at half maximum (FWHM) distribution map of a specific crystal plane of the target pixel, and misfit degree of the single-crystal high-temperature alloy. Distribution map.

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