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

Abstract

The invention discloses a single-crystal single-pixel data acquisition and analysis method based on a neutron time-of-flight technology. The method comprises the following steps: carrying out preliminary orientation on a single crystal to be detected; performing a TOF diffraction experiment on the to-be-detected single crystal, and rotating a diffraction spot of a to-be-detected crystal face to a specified position of a detector according to a preliminary orientation result; screening a target pixel according to single-pixel diffraction data on the detector to obtain a target pixel position and a diffraction spectrum thereof; fitting processing is carried out to acquire interplanar spacing and full width at half maximum of a specific diffraction crystal face of each pixel point; dot matrix strain of different target pixels is calculated, an interplanar spacing distribution diagram, a dot matrix strain distribution diagram and a full width at half maximum distribution diagram of specific crystal faces of the target pixels are drawn, and a mismatch degree distribution diagram can also be drawn for single-crystal high-temperature alloy. The method can be used for extracting the microstructure information of different areas in the diffraction volume of the single crystal material, and has important significance for perfecting the design, preparation and production process and service damage evaluation of the single crystal material and prolonging the service life of the material.

Description

Technical Field

[0001] The present invention belongs to the technical field of neutron diffraction, and particularly relates to a method for collecting and analyzing single-crystal single-pixel data based on neutron time-of-flight (TOF) technology. Background Art

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

[0003] In existing single-crystal related research using TOF technology, the total diffraction spectrum generated by the superposition of all diffraction beams on the reflection plane is used, and the average lattice information of the material within the neutron diffraction volume is obtained. Existing research has found that the single crystals obtained in actual production are not perfect single crystals. Their diffraction spots often deviate from the ideal situation, are unevenly distributed in reciprocal space, and there is a certain degree of divergence. This unevenly distributed divergent diffraction spot corresponds to the diffraction information of different micro-regions inside the material. Therefore, through the single-pixel analysis of the diffraction spots, new lattice information can be extracted to further reveal the microstructural and deformation inhomogeneity of the material. Summary of the Invention

[0004] In view of the deficiencies of the existing methods, the purpose of the present invention is to provide a method for collecting and analyzing single-crystal single-pixel data based on neutron TOF technology, which can extract the microstructural information of different regions within the diffraction volume of a single-crystal material through in-depth single-pixel analysis of the TOF diffraction information of the single crystal, and reveal the micro-inhomogeneity of the material.

[0005] The present invention realizes the above purpose through the following technical solutions:

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

[0007] Perform preliminary orientation on the single crystal to be measured;

[0008] Perform a TOF diffraction experiment on the single crystal to be measured, rotate the diffraction spots of the crystal plane to be measured to the specified position on the detector according to the results of the preliminary orientation, and then start collecting neutron diffraction data;

[0009] Extract the single-pixel diffraction data on the detector, screen the target pixels according to the single-pixel diffraction data, and obtain the positions of the target pixels and their diffraction spectra;

[0010] Perform fitting processing on the diffraction spectra of all the finally screened target pixels to obtain the lattice plane spacing and full width at half maximum of specific diffraction lattice planes of each pixel point;

[0011] Calculate the lattice strain of different target pixels, and draw the distribution diagrams of the lattice plane spacing, lattice strain, and full width at half maximum of the target pixels.

[0012] Further, the preliminary orientation of the single crystal to be measured 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 on the single crystal to be measured, and obtaining the orientation of the specified lattice plane to be measured relative to the single crystal sample coordinate system; if there are multiple lattice planes to be measured, the spatial orientations of the multiple lattice planes to be measured relative to the single crystal sample coordinate system are determined together.

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

[0014] Further, perform a TOF diffraction experiment on the single crystal to be measured, rotate the diffraction spots of the lattice plane to be measured to the specified position on the detector according to the results of the preliminary orientation, and then start collecting neutron diffraction data, including:

[0015] Zero the initial coordinates of the hexapod displacement stage, fix the single crystal sample on the sample stage with the hexapod displacement stage, and make the normal direction of the lattice plane to be measured lie on the angular bisector of the angle between the central axis of the detector and the incident beam;

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

[0017] Obtain the initial rotation center coordinates (X2, Y2, Z2) of the hexapod displacement stage;

[0018] Calculate the relative differences ΔX = X0 – X2, ΔY = Y0 – Y2, ΔZ = Z0 - Z2 between the coordinates (X0, Y0, Z0) of the point to be measured and the initial rotation center coordinates (X2, Y2, Z2) of the hexapod displacement stage, and set the rotation center position in the control software of the hexapod displacement stage through this difference to ensure that the rotation center of the hexapod displacement stage is located at the point to be measured of the sample;

[0019] Turn on the neutron beam, set a short acquisition time (such as 2 min), judge the orientation of the single crystal sample through the position of the diffraction spot on the detector, and then use the hexapod displacement stage to adjust the spatial orientation of the single crystal sample and re-collect the diffraction information until the diffraction spot of the lattice plane to be measured is rotated to the specified position on the detector;

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

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

[0022] Obtain the single-pixel raw data of the detector where the diffraction spot is located. This raw data includes the two-dimensional position coordinates of each pixel on the detector and the complete one-dimensional diffraction spectrum corresponding to each pixel, including the interplanar spacing value and the diffraction intensity value.

[0023] Draw a two-dimensional distribution map of the diffraction intensity of all pixels on the detector. The diffraction intensity is the total integrated intensity of Int corresponding to all interplanar spacing values within the neutron wavelength range.

[0024] Based on the two-dimensional distribution map of the total integrated diffraction intensity, set an intensity threshold or directly specify the coordinate position of the target pixel, thereby determining the coordinate position of the target pixel and extracting the diffraction spectrum of the target pixel point.

[0025] Use a model function to fit the diffraction spectrum of the target pixel point. According to the original data peak shape and fitting variance of different target pixel points, judge whether the data quality of each target pixel point meets the fitting requirements; good-quality diffraction data means that the overall peak shape is relatively smooth and the fitting variance with the model function is small; for this purpose, thresholds for peak shape smoothness and fitting variance can be set to determine whether the data meets the fitting requirements, and the threshold can be selected appropriately according to the user's experience.

[0026] If the data quality of each target pixel point meets the requirements, extract 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 point does not meet the requirements, merge the target pixel and its adjacent pixels, and then judge 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, when merging the target pixel and its neighboring pixels, the merging method adopted is 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 pixels to be merged (e.g., 2×2 merging), the center coordinates of the merged pixel can be selected arbitrarily but should be as close as possible to the original target pixel; when the target pixel can be located at the center of the pixels to be merged (3×3 merging), the center coordinates of the merged pixel remain the same as those of the original target pixel.

[0031] Further, for single-crystal superalloys, by fitting and peak splitting the diffraction spectra of the selected target pixels, the lattice constants of the γ and γ′ phases are calculated using the obtained interplanar spacing d and crystallographic knowledge. Based on the lattice constants, the mismatch degree δ between the two phases is calculated, and a distribution map of the mismatch degree δ is plotted.

[0032] Further, based on the analysis results of the single-crystal single-pixel data obtained by the above method, the microstructural heterogeneity and the non-uniformity of micro-deformation during the production, manufacturing, and service processes of single-crystal materials are analyzed, high-precision orientation information inside the material is obtained, and a quantitative analysis of damage behavior is carried out; the analysis results of the single-crystal single-pixel data include at least one of the following: a distribution map of the interplanar spacing of specific crystal planes of the target pixel, a distribution map of lattice strain, a distribution map of full width at half maximum, and a distribution map of the mismatch degree δ of single-crystal superalloys.

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

[0034] By performing single-pixel analysis on the diffraction signals of single-crystal materials under TOF technology, the present invention extracts the microstructural diffraction information of different regions inside single-crystal materials. Compared with the prior art method of directly analyzing the average information of all diffraction beams, it can reveal the microstructural heterogeneity and the non-uniformity of micro-deformation during the production, manufacturing, and service processes of single-crystal materials, obtain high-precision orientation information inside the material and quantitative analysis of damage behavior that cannot be achieved by conventional characterization and analysis methods, and is of great significance for improving the design, preparation process, service damage evaluation, and service life of single-crystal materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a schematic flow chart of a method for collecting and analyzing single-crystal single-pixel data based on neutron TOF technology provided by an embodiment of the present invention;

[0036] Figure 2 is the single-crystal orientation result obtained by using the EBSD technology in an embodiment of the present invention;

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

[0038] Figure 4It is a real-time acquisition diagram of the detector when the diffraction spots on the crystal plane of the single-crystal superalloy (100) are located at the ideal positions in an embodiment of the present invention;

[0039] Figure 5 It is a two-dimensional distribution diagram of the diffraction intensities of all pixels on the selected detector module of the single-crystal superalloy in an embodiment of the present invention;

[0040] Figure 6 It is a schematic diagram of the merging method for merging adjacent pixels of the target pixel in an embodiment of the present invention;

[0041] Figure 7(a) and Figure 7(b) are respectively the fitting results before and after merging of a target pixel in an embodiment of the present invention, where Figure 7(a) is the fitting result without merging, and Figure 7(b) is the fitting result after 3×3 merging;

[0042] Figure 8 It is a distribution diagram of the intensities of all the selected target pixels in an embodiment of the present invention;

[0043] Figure 9(a) and Figure 9(b) are respectively the distribution diagram of the crystal plane spacing d and the full width at half maximum FWHM distribution diagram of all the target pixels in an embodiment of the present invention, where Figure 9(a) is the distribution diagram of the crystal plane spacing d, and Figure 9(b) is the full width at half maximum FWHM distribution diagram;

[0044] Figure 10 It is a distribution diagram of the mismatch degrees between the γ and γ' phases of all the target pixels of the single-crystal superalloy in an embodiment of the present invention. Detailed implementation manners

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention. The following further illustrates the present invention with reference to the accompanying drawings.

[0046] To enable those skilled in the art to better understand the technical solutions of the present invention, the following will be combined with the attached Figures 1 to 3 A further detailed introduction to the present invention will be made.

[0047] The present invention provides a method for single-crystal single-pixel data acquisition and analysis based on neutron TOF technology. The data acquisition and analysis process is as Figure 1 shown, and includes the following steps:

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

[0049] S200: Use a spallation neutron source diffraction device equipped with a high-precision hexapod displacement stage to carry out the TOF diffraction experiment of the single crystal. According to the preliminary orientation result of the single crystal in step S100, after installing the sample, rotate the diffraction spot of the crystal plane to be measured to the specified position (near the center position) of the detector at a specific orientation in real space through the high-precision hexapod displacement stage, and then start collecting neutron diffraction data.

[0050] S300: Obtain the single-pixel diffraction data on a specific detector from the data acquisition backend system, draw a two-dimensional distribution map of the diffraction intensity of all pixels on the detector, screen the target pixels by setting an intensity threshold or directly specifying the target pixel coordinates, and obtain the position of the target pixels and their diffraction spectra. Select a suitable model function, and judge whether the diffraction data quality of each target pixel point all meets the fitting requirements through the peak shape and fitting variance of the original data of the diffraction spectrum of the target pixel. If it meets the requirements, directly use the single-pixel diffraction spectrum of the target pixel; if the data quality of the target pixel point does not meet the requirements, merge the pixel data of the target pixel and its adjacent pixels by customizing the adjacent pixel range of the target pixel, and judge again whether the data quality meets the requirements. Finally, it is necessary to ensure that the diffraction data quality of all target pixels meets the fitting requirements. Among them, the target pixel refers to the target single pixel of interest to be analyzed in the detector.

[0051] S400: Perform final fitting processing on the diffraction spectra of the target pixels screened in step S300 to obtain the lattice plane spacing d value, full width at half maxima (FWHM), etc. of a specific diffraction crystal plane.

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

[0053]

[0054] Among them, is the measured lattice plane spacing of the reference sample (h k l) crystal plane, d (hkl) is the measured lattice plane spacing of the (h k l) crystal plane of other samples.

[0055] S600: For single-crystal superalloys, the lattice constants a of the γ and γ′ phases can be obtained using the lattice plane spacing d fitted in step S400, and then the mismatch δ between the two phases can be calculated. Subsequently, a distribution map of the mismatch δ is plotted. The calculation formula for δ is as follows:

[0056]

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

[0058] Preferably, in step S100, before conducting the neutron diffraction experiment, the single crystal needs to be preliminarily oriented. This orientation requires obtaining the orientation of the specified crystal plane to be measured (h k l) relative to the coordinate system of the single-crystal sample. If there are multiple crystal planes to be measured, the spatial orientations of these crystal planes relative to the coordinate system of the single-crystal sample need to be determined together. The best orientation accuracy is 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, and Rz of the hexapod displacement stage are reset to zero. Fix the single-crystal sample on the sample stage with the hexapod displacement stage, and make the normal direction of the crystal plane (h k l) to be measured lie on the angular bisector of the angle between the line connecting the detector center and the sample (central axis) and the incident beam;

[0061] S202: Use a high-precision robotic arm to obtain the coordinates (X1, Y1, Z1) of the point to be measured on the sample. Utilize the X, Y, and Z three-axis heavy-duty stages located below the hexapod displacement stage to move the point to be measured to the neutron beam diffraction center coordinates (X0, Y0, Z0);

[0062] S203: Use a high-precision robotic arm to obtain the initial rotation center coordinates (X2, Y2, Z2) of the hexapod displacement stage at this time;

[0063] S204: Calculate the relative differences ΔX = X0 – X2, ΔY = Y0 – Y2, and ΔZ = Z0 - Z2 between the coordinates (X0, Y0, Z0) of the point to be measured on the sample and the initial rotation center coordinates (X2, Y2, Z2) of the hexapod displacement stage. Set the rotation center position in the control software of the hexapod displacement stage through these differences to ensure that the rotation center of the hexapod displacement stage is located at the point to be measured on the sample;

[0064] S205: Turn on the neutron beam. Set a relatively short data acquisition time according to the actual situation. Subsequently, use the hexapod displacement stage to adjust the spatial orientation of the single-crystal sample until the diffraction spot of the crystal plane (h k l) to be measured is rotated to the specified position on the detector;

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

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

[0067] S301: Obtain the single-pixel raw data of the detector where the diffraction spot is located. The main information included in this raw data is: the two-dimensional position (X, Y) of the pixel on the detector, the lattice plane spacing d value of the diffraction spectrum in the pixel, and the diffraction intensity Int value;

[0068] S302: Plot the two-dimensional distribution map of the diffraction intensity of all pixels on the selected detector. This diffraction intensity is the total integrated intensity of all d values covered by the neutron band used in the experiment;

[0069] S303: According to the 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 point, and extract the diffraction spectra of these target pixel points;

[0070] S304: Use the selected model function to fit the diffraction spectra of the determined target pixel points. According to the original data peak shapes and fitting variances of different target pixel points, judge whether the data quality of each target pixel point all meets the fitting requirements. If so, proceed to step S306; otherwise, enter step S305;

[0071] S305: Merge adjacent pixels of the target pixel. Since the d values of the diffraction spectra of each pixel are the same, when merging pixels, the intensity Int values can be directly linearly superimposed; after superimposition, proceed to step S304 again;

[0072] S306: Extract the diffraction spectra of the target pixels whose diffraction data quality meets the fitting requirements in step S304, that is, single-pixel diffraction spectra or merged-pixel diffraction spectra.

[0073] Preferably, the model function used in step S304 is generally the 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 fitting calculated value of the diffraction intensity, y 0 is the diffraction peak background, A is the diffraction peak area, that is, the integrated intensity, η is the proportion of the Lorentz function in the Pseudo-Voigt function, x c is the diffraction peak position, w is the diffraction peak width, and x is the abscissa lattice plane spacing d of the diffraction spectrum.

[0076] Preferably, in step S400, batch processing is required for the selected target pixels to obtain the d values and full width at half maximum (FWHM) of all target pixels.

[0077] Preferably, in step S500, the diffraction intensity distribution map, crystal plane spacing d distribution map, and FWHM distribution map of the selected target pixels can be plotted; if the lattice strain of different target pixels is calculated, the lattice strain distribution map can also be plotted.

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

[0079] Here, taking nickel-based single crystal superalloy as an example, the technical solution of the present invention will be specifically described.

[0080] 1. Using a scanning electron microscope equipped with an EBSD system, the single crystal superalloy to be measured is preliminarily oriented, as Figure 2 shown, to obtain the relationships between the crystal planes (100), (001) to be measured and the sample coordinate system;

[0081] 2. Using the general powder diffraction spectrometer of the China Spallation Neutron Source to carry out the TOF diffraction experiment of the single crystal. This spectrometer is equipped with a high-precision hexapod displacement stage, which can meet the single crystal test requirements. The steps of the TOF diffraction experiment of the single crystal include:

[0082] a) According to the single crystal orientation result in step 1, install the sample to ensure that the normal directions of the crystal planes (100), (001) to be measured are located on the angular bisector of the angle between the detector center and the incident beam, Figure 3 which gives the diffraction geometry schematic diagram during sample testing.

[0083] b) Subsequently, by moving the heavy load stage and setting a new rotation center of the hexapod displacement stage, make the neutron beam diffraction center, the sample point to be measured, and the rotation center of the hexapod displacement stage coincide.

[0084] c) Turn on the neutron beam current, set the data acquisition time to 2 min, and then use the hexapod displacement stage to adjust the spatial orientation of the single crystal sample to rotate the diffraction spots of the crystal planes (100), (001) to be measured to the detector center, as Figure 4 shown;

[0085] d) Finally, set the data acquisition time to 240 min to ensure that the intensity of the single pixel data meets the requirements of diffraction spectrum fitting.

[0086] 3. Extract Figure 3 the single pixel diffraction data on detectors 1 and 2 in The total integrated intensity of the diffraction intensity Int corresponding to all d values covered, as Figure 5 shown. The Pseudo-Voigt function is selected as the model function. Since the original data diffraction intensity of the target pixel is low and the fitting quality is poor, adjacent pixels of the target pixel are merged. The merging method is as Figure 6 shown, including 2×2 merging and 3×3 merging. The fitting spectra before merging and after 3×3 merging of the same pixel are shown in Figures 7(a) and 7(b) respectively. The total diffraction intensity threshold is set to 150, the target pixels are screened out, their pixel positions and diffraction spectra are obtained, and the intensity distribution map of the screened target pixels is as Figure 8 shown. Among them, two detectors (detector 1 and detector 2) are used to simultaneously obtain information on two orientations, thereby improving efficiency. In other embodiments, only one detector can also be used.

[0087] 4. Fit and deconvolute the original diffraction spectra of the screened target pixels to obtain the interplanar spacing d value, full width at half maximum (FWHM), etc. of the (100) crystal plane;

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

[0089] 6. For single-crystal superalloys, the interplanar spacing d of the (100) crystal plane can be considered equal to the lattice constant a. Therefore, the lattice constants a of both the γ and γ′ phases can be obtained simultaneously, and their mismatch degree δ is calculated. Subsequently, the distribution map of the mismatch degree δ is drawn, as Figure 10 shown.

[0090] In this embodiment, the size of a single pixel of the detector is 4×4 mm, and the detector is 2 m away from the sample. According to the diffraction intensity distribution map in step 3, the coverage range of the diffraction spot is about 30×12 pixels. Therefore, the maximum internal orientation difference of this single-crystal superalloy near the (100) crystal plane is about The distribution maps of the interplanar spacing d, FWHM, and mismatch degree δ in steps 5 and 6 show that the mismatch degrees in different regions of this single-crystal alloy are mostly distributed between -0.3% and -0.2%, and the maximum lattice constant difference between different regions is about This value is close to the difference in lattice constants between the γ and γ′ phases in the alloy. Additionally, in the region with a smaller lattice constant, the (100) crystal plane of the γ′ phase has a larger full width at half maximum (FWHM). This indicates that during the directional solidification process of this single-crystal alloy, due to compositional segregation, there are significant differences in the size and uniformity of the lattice constants of the γ′ phase in different regions, which may affect the local micro-mechanical behavior of the alloy during subsequent service.

[0091] The specific embodiments of the present invention disclosed above are intended to help understand the content of the present invention and implement it accordingly. Those of ordinary skill in the art can understand that various substitutions, changes, and modifications are possible without departing from the spirit and scope of the present invention. The present invention should not be limited to the content disclosed in the embodiments of this specification, and the protection scope of the present invention is subject to the scope defined by the claims.

Claims

1. A single crystal single pixel data acquisition and analysis method based on neutron time-of-flight technology, characterized in that: The following steps are involved: Carry out preliminary orientation of the single crystal to be tested; Perform TOF diffraction experiment on the single crystal to be tested, rotate the diffraction spot of the crystal surface to be tested to the specified position of the detector according to the result of preliminary orientation, and then start collecting neutron diffraction data; Extracting single-pixel diffraction data on the detector, screening target pixels according to the single-pixel diffraction data, and obtaining the target pixel position and its diffraction spectrum; Fitting the diffraction spectra of all the target pixels finally screened out to obtain the interplanar spacing and half-height width of the specific diffraction crystal plane of each pixel point; Calculate the lattice strain of different target pixels, and draw the crystal plane spacing distribution map, lattice strain distribution map, and half-height width distribution map of the target pixels.

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 preliminary orient the single crystal to be tested, and obtaining the orientation of a specified crystal plane to be tested relative to the single crystal sample coordinate system; if there are multiple crystal planes to be tested, then determining the spatial orientations of multiple crystal planes to be tested relative to the single crystal sample coordinate system.

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

4. The method according to claim 1, characterized in that: The TOF diffraction experiment is performed on the single crystal to be tested, and the diffraction spot of the crystal surface to be tested is rotated to the specified position of the detector according to the result of the preliminary orientation, and then the neutron diffraction data is collected, including: The initial coordinates of the hexapod are reset to zero, and the single crystal sample is fixed on the sample stage with the hexapod so that the normal direction of the crystal surface to be measured is located on the bisector of the angle between the central axis of the detector and the incident beam; Use the three-axis heavy-load stage located under the hexapod to move the point to be measured to the coordinates (X0, Y0, Z0) of the neutron beam diffraction center; Get the initial rotation center coordinates (X2, Y2, Z2) of the hexapod. Calculate the relative difference between the coordinates of the test point (X0, Y0, Z0) and the initial rotation center coordinates of the hexapod (X2, Y2, Z2) ΔX = X0–X2, ΔY = Y0–Y2, ΔZ = Z0-Z2, and set the rotation center position in the hexapod control software according to the difference to ensure that the rotation center of the hexapod is located at the test point of the sample; 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 the hexapod to adjust the spatial orientation of the single crystal sample and re-collect diffraction information until the diffraction spot on the crystal plane to be measured is rotated to the specified position of the detector; Start formally collecting neutron diffraction data and set a longer collection time to ensure that the intensity of single-pixel data meets the diffraction spectrum fitting requirements.

5. The method according to claim 1, characterized in that The step of screening the target pixel according to the single pixel diffraction data comprises: Obtaining single-pixel raw data of the detector where the diffraction spot is located, the raw data includes the two-dimensional position coordinates of each pixel on the detector, and the complete one-dimensional diffraction spectrum corresponding to each pixel, including the crystal plane spacing value and the diffraction intensity value; Draw a two-dimensional distribution diagram of the diffraction intensity of all pixels on the detector. The diffraction intensity is the total integrated intensity of the diffraction intensity Int corresponding to all crystal plane spacing values ​​within the coverage range of the neutron band; According to the two-dimensional distribution diagram of the total integrated intensity of diffraction, an intensity threshold is set or the coordinate position of the target pixel is directly specified, so as to determine the position coordinate of the target pixel and extract the diffraction spectrum of the target pixel point; The diffraction spectrum of the target pixel point is fitted using the model function, and according to the peak shape of the original data of different target pixel points and the fitting variance, it is judged whether the data quality of each target pixel point meets the fitting requirements; If the data quality of each target pixel point meets the requirements, the final diffraction spectrum of the target pixel is extracted according to 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 adjacent pixels are merged, and it is determined again whether the data quality meets the requirements; Ultimately, it is necessary to ensure that the data quality of all target pixels meets the fitting requirements.

6. The method according to claim 5, characterized in that The model function is a Pseudo-Voigt function or other suitable model function, and the formula of the Pseudo-Voigt function is: Where y is the calculated 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, and x is c is the diffraction peak position, w is the diffraction peak width, and x is the horizontal coordinate crystal plane spacing d of the diffraction spectrum.

7. The method according to claim 5, characterized in that The target pixel and its adjacent pixels are merged in an m×n merging manner, wherein m is equal to n or m is not equal to n; When the target pixel cannot be located at the center of the pixels to be merged, the center coordinates of the merged pixel are selected by yourself but should be as close to the original target pixel as possible; 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 original target pixel coordinates.

8. The method according to claim 1, characterized in that For single crystal high-temperature alloys, the diffraction spectra of the screened target pixels are fitted and peak separated, and the lattice constants of the γ and γ′ phases are calculated using the obtained crystal plane spacing d and crystallographic knowledge. The mismatch δ of the two phases is calculated based on the lattice constants, and a mismatch δ distribution diagram is drawn.

9. The method according to claim 8, characterized in that The calculation formula of the mismatch degree δ is: Among them, a γ′ is the lattice constant of the γ′ phase in the single crystal superalloy, a γ is the lattice constant of the γ phase.

10. The method according to any one of claims 1 to 9, characterized in that: According to the analysis results of the obtained single crystal single pixel data, the microstructural heterogeneity and micro deformation in the production and service process of the single crystal material are analyzed, and the high-precision orientation information inside the material is obtained and the damage behavior is quantitatively analyzed; the analysis results of the single crystal single pixel data include at least one of the following: a crystal plane spacing distribution map of a specific crystal plane of the target pixel, a lattice strain distribution map, a half-height width distribution map, and a mismatch δ distribution map of the single crystal high-temperature alloy.

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