System and method for analyzing microstructure strain dynamic evolution of material under ultra-high temperature deformation

Abstract

The application provides a material ultra-high temperature deformation microstructure strain dynamic evolution analysis system and method, the system cuts a sheet-shaped material to be tested by a sample preparation mechanism, and pretreats an effective material sample according to test requirements; a high-contrast random speckle is made for the material sample by a test speckle forming mechanism; then the speckle material sample in an ultra-high temperature environment is tested in situ based on a set displacement rate by an in-situ stretching observation mechanism, and a laser scanning confocal microscope is used to observe the video and dynamic image of the sample in real time; finally, the dynamic image of the test process is analyzed based on a DIC algorithm by a deformation strain evolution analysis module, a displacement field of the surface of the speckle material sample is constructed, and a corresponding strain field is calculated; the comprehensiveness limitation in the prior art is overcome, the micro failure mechanism of the ultra-high temperature material can be finely observed, the practicality is higher, and the strain field evolution of various material deformations can be further reliably analyzed.

Description

Technical Field

[0001] This invention relates to the field of material failure observation and analysis technology, and in particular to an analysis system and method for the dynamic evolution of strain in the microstructure of materials under ultra-high temperature deformation. It is used to observe in situ the surface microstructure, strain evolution, crack initiation, propagation, and failure of materials under ultra-high temperature conditions under tensile / compressive (fatigue) loads, and to analyze the evolution law. Background Technology

[0002] The microstructure of materials interacts with their service environment (such as coupling with temperature and stress fields), directly affecting their performance and service life. In recent years, the field has continuously dedicated itself to researching in-situ testing techniques that can accurately simulate material service conditions, enabling microscopic testing of material surface structures, observing changes in the microstructure of material surfaces under external fields at different scales, and obtaining information on the fracture and damage behavior of materials under loading.

[0003] The stress and strain characteristics of materials are closely related to their failure behavior. In particular, the stress and strain state of materials in the micrometer-scale micro-regions is often used to explain macroscopic failure phenomena. Current conventional testing techniques are insufficient for micrometer-scale stress and strain testing and analysis. In recent years, the newly developed electron backscatter diffraction (EBSD) technique has become a powerful tool for analyzing the stress and strain state of micro-regions. Scanning electron microscopy (SEM) with an in-situ tensile stage can study stress and strain concentration during deformation. However, the maximum allowable experimental temperature for SEM under high-temperature conditions is 1200℃, which cannot meet the experimental requirements for in-situ observation of ultra-high temperature tensile stress. Furthermore, EBSD technology measures lattice strain and cannot analyze the plastic strain of materials.

[0004] The information disclosed in the background section of this invention is intended only to enhance the understanding of the general background of this invention, and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides an analysis system for the dynamic evolution of strain in the microstructure of materials under ultra-high temperature deformation. By combining ultra-high temperature laser scanning confocal microscopy with DIC analysis technology, it enables in-situ observation and analysis of the microstructure evolution and dynamic strain evolution during material deformation at ultra-high temperatures. This reveals the initiation and propagation mechanism of cracks at ultra-high temperatures at a microscale, providing an effective research method for studying the microscopic failure mechanism of ultra-high temperature materials. In one embodiment, the system includes:

[0006] The sample preparation mechanism is configured to cut sheet-shaped materials to be tested and pre-treat them according to the testing requirements to obtain effective material samples for testing to achieve ultra-high temperature deformation tests of materials.

[0007] The experimental speckle forming mechanism is configured to generate high-contrast random speckles for the obtained material sample, thereby obtaining a speckled material sample; the speckles are speckle particles with sizes in the submicron / nanometer range and stable performance.

[0008] The in-situ tensile observation mechanism is configured to perform in-situ tensile tests on the speckled material sample in a high-temperature heating furnace environment cavity using a high-temperature tensile compression system based on a set displacement rate. During the test, a laser scanning confocal microscope is used to observe and save the video and dynamic images of the sample in real time.

[0009] The deformation strain evolution analysis module, which is connected to the in-situ tensile observation mechanism, is configured to analyze the dynamic images of the test process based on the DIC algorithm, construct the displacement field of the speckled material sample surface and calculate the corresponding strain field.

[0010] Preferably, the sample preparation mechanism includes a material cutting module and a material processing module;

[0011] The material cutting module is used to cut sheet materials of a set size from the plate using wire cutting, according to the experimental requirements of ultra-high temperature in-situ observation.

[0012] The material processing module is configured to use a sandpaper grinding device to grind the cut sheet material on both sides, select one side as the observation surface, and use a metallographic sandpaper device to grind it step by step until the observation requirements are met; then a marking device is used to mark the observation area on the observation surface, and the marking device is a microhardness tester.

[0013] Furthermore, the experimental speckle forming mechanism includes:

[0014] The primer spraying module is configured to uniformly spray a set thickness of matte high-temperature primer onto the observation surface of the material test while ensuring that the surface of the material sample is clean and free of contaminants.

[0015] The speckle spraying module is configured to further spray a diffused and randomly distributed high-contrast high-temperature paint onto a high-temperature primer.

[0016] As a further improvement of the present invention, the experimental speckle forming mechanism also includes

[0017] The speckle sample baking module uses a muffle furnace to bake the material sample after spraying speckles at a constant temperature according to the set temperature and time, so that the speckles have high temperature stability.

[0018] Furthermore, the in-situ tensile observation mechanism includes a tensile compression worktable and two loading mechanisms disposed within the environmental cavity of the high-temperature heating furnace.

[0019] The loading mechanism is used to install speckled material samples. The first loading mechanism is fixed on the tensile compression worktable, and the other is connected to the linear driver of the high-temperature tensile compression system.

[0020] Optionally, the laser scanning confocal microscope of the in-situ tensile observation mechanism uses a purple laser VL2000DX with a wavelength of 408nm and a scanning speed of 15-120 frames per second.

[0021] Furthermore, the in-situ tensile observation mechanism also includes a test pretreatment module, which is configured to evacuate the vacuum chamber and purge it with ultra-high purity argon gas before heating after the speckled material sample is mounted on the loading mechanism to reduce the oxygen content and protect the sample surface from oxidation.

[0022] As a further improvement of the present invention, the laser scanning confocal microscope tracks the marked area of ​​the material sample in real time during the shooting process, keeps the marked area in the center of the field of view throughout the tensile process, saves the observation video in real time, saves the pictures at the corresponding time intervals according to the set time intervals, and records the tensile curve of the test in real time.

[0023] Preferably, the deformation-strain evolution analysis module includes an image filtering unit and a strain analysis unit;

[0024] The image filtering unit is configured to filter material surface photographs obtained by ultra-high temperature laser scanning confocal microscope during the in-situ stretching process, and select effective speckle images whose grayscale distribution meets the set requirements.

[0025] The strain analysis unit is configured to use the DIC algorithm to calculate the selected valid speckle images, realize the matching of deformation points on the object surface, reconstruct the coordinates of the calculated points on the object surface based on the disparity data of each corresponding point, and obtain the displacement field of the object surface by comparing the coordinate changes of each point in the measurement area of ​​each deformation state. Then, the strain field of the object surface is calculated using GOM software and VIC-2D software.

[0026] Based on the application aspects of the system described in any one or more of the above embodiments, the present invention also provides a method for analyzing the dynamic evolution of strain in the microstructure of materials under ultra-high temperature deformation, the method comprising:

[0027] The sample preparation steps involve cutting the material to be tested into sheet-like pieces and then pre-treating it according to the testing requirements to obtain effective material samples for testing to achieve ultra-high temperature deformation tests of materials.

[0028] The experiment involves the following steps: creating high-contrast random speckles on the obtained material sample to obtain a speckled material sample; the speckles are speckled particles with sizes in the submicron / nanometer range and stable performance.

[0029] The in-situ tensile observation procedure involves conducting an in-situ tensile test on the speckled material sample within a high-temperature heating furnace environment chamber using a high-temperature tensile compression system based on a set displacement rate. During the test, a laser scanning confocal microscope is used to observe and save the video and dynamic images of the sample in real time.

[0030] The deformation strain evolution analysis steps are configured to analyze the dynamic images of the test process based on the DIC algorithm, construct the displacement field on the surface of the speckled material sample, and calculate the corresponding strain field.

[0031] Compared with the closest prior art, the present invention also has the following beneficial effects:

[0032] This invention provides an analysis system and method for the dynamic evolution of microstructure strain in materials under ultra-high temperature deformation. After cutting and preprocessing the material to be tested into effective material samples, a high-contrast random speckle pattern is created on the material samples through an experimental speckle forming mechanism. This provides a basis for the analysis of the evolution of tensile stress field in materials based on the DIC algorithm, and can also improve the quality and stability of the observed images.

[0033] Furthermore, based on a set displacement rate, in-situ tensile tests were conducted on speckled material samples under ultra-high temperature conditions. A laser scanning confocal microscope was used to observe the video and dynamic images of the samples in real time. Finally, the deformation-strain evolution analysis module analyzed the dynamic images of the test process based on the DIC algorithm, constructed the displacement field on the surface of the speckled material sample, and calculated the corresponding strain field. This solved the problem that conventional DIC tests cannot observe the microstructure using high-speed cameras, and broke through the test temperature limitations of traditional technologies. It also enables more refined observation of the microscopic failure mechanism of ultra-high temperature materials, making it more practical. Moreover, it can further reliably analyze the strain dynamic evolution and crack initiation mechanism of tensile deformation failure processes of various materials under ultra-high temperature conditions.

[0034] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the description, claims, and drawings. Attached Figure Description

[0035] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0036] Figure 1 This is a schematic diagram of the structure of the analysis system for the dynamic evolution of strain in the microstructure of materials under ultra-high temperature deformation provided in an embodiment of the present invention;

[0037] Figure 2 This is an example diagram of the material sample size of the analysis system for the dynamic evolution of strain in the microstructure of ultra-high temperature deformation of materials provided in the embodiments of the present invention;

[0038] Figure 3 This is an example diagram of speckle preparation of the analysis system for the dynamic evolution of strain in the microstructure of materials under ultra-high temperature deformation provided in another embodiment of the present invention;

[0039] Figure 4 This is a diagram showing the composition of the in-situ tensile observation mechanism of the analysis system for the dynamic evolution of strain in the microstructure of materials under ultra-high temperature deformation according to an embodiment of the present invention.

[0040] Figure 5 This is a schematic diagram illustrating the DIC algorithm principle of the analysis system for the dynamic evolution of microstructure strain in ultra-high temperature deformation of materials provided in an embodiment of the present invention.

[0041] Figure 6 This is a flowchart illustrating the analytical method for the dynamic evolution of strain in the microstructure of materials under ultra-high temperature deformation, provided in another embodiment of the present invention. Detailed Implementation

[0042] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples. Those skilled in the art will then fully understand how the present invention uses technical means to solve technical problems and achieve technical effects, and will be able to implement the present invention specifically based on the above-described implementation process. It should be noted that, as long as there is no conflict, the various embodiments and features of the present invention can be combined with each other, and the resulting technical solutions are all within the protection scope of the present invention.

[0043] Although the flowchart describes the operations as sequential processes, many of these operations can be performed in parallel, concurrently, or simultaneously. The order of the operations can be rearranged. A process can terminate when its operation is complete, but it may also have additional steps not included in the diagram. A process can correspond to a method, function, procedure, subroutine, subroutine, etc.

[0044] The terms “first,” “second,” etc., may be used herein to describe various units, but these units should not be limited by these terms; they are used merely to distinguish one unit from another. The term “and / or” as used herein includes any and all combinations of one or more of the associated listed items. When a unit is referred to as “connected” or “coupled” to another unit, it may be directly connected or coupled to said other unit, or there may be intermediate units present.

[0045] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments. Unless the context clearly indicates otherwise, the singular forms “a” and “an” as used herein are also intended to include the plural. It should also be understood that the terms “comprising” and / or “including” as used herein specify the presence of the stated features, integers, steps, operations, units, and / or components, without excluding the presence or addition of one or more other features, integers, steps, operations, units, components, and / or combinations thereof.

[0046] The interaction between the microstructure of a material and its service environment (such as coupling with temperature and stress fields) directly affects its performance and service life. In recent years, both domestic and international researchers have been developing in-situ testing techniques capable of simulating material service conditions. These techniques combine loading with microscopic testing of the material's surface structure, allowing for real-time tracking and observation of the microstructural evolution of the material surface under external fields at different scales, and analysis of deformation mechanisms and fracture damage behavior. The stress and strain characteristics of a material are closely related to its failure behavior; in particular, the stress and strain states within the micrometer-scale region are often used to explain macroscopic failure phenomena. Current conventional testing techniques are insufficient for micrometer-level stress and strain testing and analysis. The newly developed electron backscatter diffraction (EBSD) technique has become a powerful tool for analyzing micro-region stress and strain states. Scanning electron microscopy (SEM) with an in-situ tensile stage combined with EBSD can study stress and strain concentration during deformation. However, the maximum allowable temperature for SEM testing in high-temperature environments is 1200℃, which cannot meet the requirements for in-situ observation of ultra-high temperature tensile stress. Furthermore, EBSD measures lattice strain, not plastic strain. Furthermore, there is currently a lack of methods to analyze the microstructure strain distribution and dynamic evolution process of materials based on observation of microstructure changes and crack initiation and propagation processes at ultra-high temperatures.

[0047] For example, CN112881195A provides a hot and cold in-situ tensile microstress testing system, which can perform tensile experiments and observations under a set temperature environment. The system uses a DIC microstrain measurement system with its imaging lens positioned directly opposite the transparent window of the tensile chamber. It combines digital image correlation (DIC) and binocular stereomicroscopy to microscopically observe and measure the three-dimensional coordinates, displacement, and strain of the specimen surface during deformation within the tensile chamber. While this system can stabilize the temperature and humidity within the tensile chamber and flexibly adjust it according to experimental needs, and the DIC microstrain measurement system provides real-time imaging and damage observation of the experimental process, its applicable test temperature conditions are limited. It cannot measure the tensile strain of materials under ultra-high temperature environments, and it cannot analyze the strain distribution and dynamic evolution of the material's microstructure based on observations of ultra-high temperature microstructural changes and crack initiation and propagation processes.

[0048] The inventors of this invention considered that laser scanning confocal microscopy (LSCM) can observe in real time and continuously the changes in the surface structure and metallography of materials under tensile / compressive (fatigue) external forces at high temperatures, as well as the initiation, propagation, and failure of cracks. At the same time, it can realize real-time, in-situ, and high-definition observation and analysis of changes in the microstructure of materials at high or even ultra-high temperatures.

[0049] Based on this, the present invention provides a scheme for analyzing the dynamic evolution of strain in the microstructure of materials under ultra-high temperature deformation using ultra-high temperature laser scanning confocal microscopy combined with DIC technology. It analyzes the microstructure evolution and strain dynamic evolution process of materials under ultra-high temperature deformation, and can reveal the initiation and development mechanism of cracks at ultra-high temperature from a microscopic scale. This overcomes the problem that existing in-situ observation techniques cannot study the deformation microstructure of materials under ultra-high temperature (above 1200℃) and are difficult to effectively analyze the strain dynamic evolution process.

[0050] The detailed flow of the analysis system according to an embodiment of the present invention will now be described in detail with reference to the accompanying drawings. Although the logical order of each operation is shown in the section on system operation principles, in some cases, the operations shown or described may be performed in a different order than that shown here.

[0051] Example 1

[0052] Figure 1 This diagram illustrates the structure of an analysis system for the dynamic evolution of strain in the microstructure of materials under ultra-high temperature deformation, as provided in Embodiment 1 of the present invention. (Refer to...) Figure 1 According to the information provided, the system includes:

[0053] The sample preparation mechanism is configured to cut sheet-shaped materials to be tested and pre-treat them according to the testing requirements to obtain effective material samples for testing to achieve ultra-high temperature deformation tests of materials.

[0054] The experimental speckle forming mechanism is configured to generate high-contrast random speckles for the obtained material sample, thereby obtaining a speckled material sample; the speckles are speckle particles with a size in the submicron or nanometer range and stable performance.

[0055] The in-situ tensile observation mechanism is configured to perform in-situ tensile tests on the speckled material sample in a high-temperature heating furnace environment cavity using a high-temperature tensile compression system based on a set displacement rate. During the test, a laser scanning confocal microscope is used to observe and save the video and dynamic images of the sample in real time.

[0056] The deformation strain evolution analysis module, which is connected to the in-situ tensile observation mechanism, is configured to analyze the dynamic images of the test process based on the DIC algorithm, construct the displacement field of the speckled material sample surface and calculate the corresponding strain field.

[0057] Based on the above-mentioned analysis system, this invention uses an ultra-high temperature laser scanning confocal microscope to obtain high-resolution images of the material deformation process in real time, solving the problem that traditional DIC tests cannot observe the microstructure using high-speed cameras. On the other hand, by combining ultra-high temperature laser scanning confocal microscope with DIC analysis technology, it solves the problem that SEM+EBSD methods cannot study the dynamic evolution of material deformation strain at ultra-high temperatures. It provides an effective research scheme for the study of the microscopic failure mechanism of ultra-high temperature materials, and can be effectively applied to various needs in the field of material failure analysis. It provides an effective observation method for the study of strain dynamic evolution and crack initiation mechanism of material deformation failure process under ultra-high temperature conditions.

[0058] In a preferred embodiment, the sample preparation mechanism includes a material cutting module and a material processing module;

[0059] The material cutting module is used to cut sheet materials of a set size from the plate using wire cutting, according to the experimental requirements of ultra-high temperature in-situ observation.

[0060] The material processing module is configured to use a sandpaper grinding device to grind the cut sheet material on both sides, select one side as the observation surface, and use a metallographic sandpaper device to grind it step by step until the observation requirements are met; then a marking device is used to mark the observation area on the observation surface, and the marking device is a microhardness tester.

[0061] Specifically, in practical applications, according to the experimental requirements of ultra-high temperature in-situ observation, in-situ tensile specimens are cut from the plate using wire cutting (selecting sheet specimens with dimensions such as...). Figure 2As shown), the gauge length is 17 mm long, 5 mm wide, and 1.5 mm thick. To facilitate the installation of the specimen onto the loading device of the in-situ tensile observation mechanism, a 5.1 mm diameter hole is reserved at the position set at the specimen clamping end for mounting (unmounting) the specimen and the loading device.

[0062] This invention provides a sheet-like specimen for high-temperature tensile testing, the dimensions of which are as follows: Figure 2 As shown, this is a standard size. In actual applications, apart from the fixed dimensions of the two ends and the dimensions of the holes corresponding to the requirements, the length, width, and thickness of the middle part can be appropriately varied.

[0063] Then, use metallographic sandpaper to grind both sides of the sample flat. One side is selected as the observation surface and is ground with metallographic sandpaper up to 2000 grit. Then, it is mechanically polished to a mirror finish to facilitate fine observation.

[0064] Furthermore, in this embodiment of the invention, a microhardness tester is used to create indentations at the four corners of the observation area for marking. The preparation load can be set to 0.5 N during indentation creation. This invention uses a microhardness tester to create indentations as markers for the observation area. While ensuring the accuracy of the marking position, even if the material sample deforms during the tensile test, the effectiveness of the marking in the observation area will not be affected, and it maintains stability even in ultra-high temperature environments.

[0065] After the sample is prepared, surface impurities are removed by alcohol cleaning or ultrasonic cleaning, and surface moisture is removed by drying.

[0066] After obtaining a clean material sample whose observation surface meets the test requirements, the sample surface must have random features in order to obtain a high-contrast random grayscale distribution image. Before measurement, the object to be measured needs to be treated with speckle spraying. This invention utilizes a test speckle forming mechanism to create high-contrast random speckles on the obtained material sample, thus obtaining a speckled material sample; in one embodiment, the test speckle forming mechanism includes:

[0067] The primer spraying module is configured to uniformly spray a set thickness of matte high-temperature primer onto the observation surface of the material test while ensuring that the surface of the material sample is clean and free of contaminants.

[0068] The speckle spraying module is configured to further spray a diffused and randomly distributed high-contrast high-temperature paint onto a high-temperature primer.

[0069] Furthermore, in a preferred embodiment, the experimental speckle forming mechanism further includes

[0070] The speckle sample baking module uses a muffle furnace to bake the material sample after spraying speckles at a constant temperature according to the set temperature and time, so that the speckles have high temperature stability.

[0071] In practical applications, this invention can first spray a layer of white high-temperature paint onto the sample as a primer, and then spray a diffused and randomly distributed black high-temperature paint onto the primer. To improve the deformation measurement sensitivity and spatial resolution of speckle photography, this invention fabricates speckle particles with submicron / nanometer-scale sizes and stable performance. Simultaneously, to ensure the stability of the prepared high-temperature speckles, the sample is baked in a muffle furnace at 230°C for 30 minutes, providing fundamental support for the effective conduct of ultra-high temperature experiments.

[0072] The quality of speckle patterns directly affects the accuracy of analytical results. To obtain reliable experimental observation results, it is important to prepare high-quality speckle patterns. This invention sets up a method for producing high-quality speckle patterns that meets the following rules:

[0073] (1) Random speckle: The speckle needs to be randomly distributed rather than regularly arranged;

[0074] (2) High contrast: The more obvious the black and white contrast, the better;

[0075] (3) Uniform size: The size of the scattered spots should be consistent, and the occurrence of scattered spots of different sizes should be avoided as much as possible;

[0076] (4) 50% ratio: black and white each account for 50%. If the sample surface is white, black speckles need to be made.

[0077] Specifically, high-quality speckle patterns meeting the above conditions can be prepared using nanoparticles and dispersants through the following operations:

[0078] The speckled materials used in the preparation process include: nanoparticles (such as nano SiO2), dispersants and substrate materials, and the equipment includes an ultrasonic cleaner and a dropper.

[0079] The preparation process includes: polishing the surface of the sample to a bright, scratch-free mirror finish; thoroughly mixing the nanopowder and dispersant according to the required ratios and dispersing them uniformly using ultrasound; keeping the treated surface horizontal, taking a portion of the well-dispersed mixture as the speckle mixture and vertically dropping it onto the surface, allowing the mixture to spread freely on the surface; then using filter paper to absorb the droplets from the edge of the droplets; then slowly tilting the surface at 40°–80° and rinsing it with anhydrous ethanol; and finally quickly drying the surface to obtain speckles on the surface.

[0080] In addition, to ensure that the speckled finished product used in the tensile test is qualified, multiple samples can be prepared in the same group after the speckles are prepared. Microscopic images of the surface to be tested are also taken, and the sample images are analyzed to identify whether the distribution of nanoparticles is uniform. If the area occupied by nanoparticles in the image meets the set value of 30%-50% of the sample, the requirements are met. If all requirements are not met, the preparation operation parameters are adjusted and the preparation is repeated according to the above steps until the speckles meet the conditions. The corresponding preparation operation parameters are then applied to the sample treatment before the tensile test in this invention.

[0081] If a speckle is 5 pixels in size, then its distance from the next speckle should also be 5 pixels (5 black pixels and 5 white pixels). Figure 3 As shown.

[0082] Furthermore, to improve the sensitivity and spatial resolution of deformation measurements, this invention fabricates speckle particles with sizes in the submicron / nanometer range and stable performance. The specific method for preparing the speckle particles is as follows:

[0083] (1) Ensure that the surface of the test sample is clean and free of dirt;

[0084] (2) Spray a layer of white high-temperature paint on the sample as a primer. Shake well before spraying to avoid blockage during the spraying process.

[0085] (3) Spray white matte paint evenly, and the thickness should not be too thick or too thin;

[0086] (4) Then, a diffuse and randomly distributed black high-temperature paint is sprayed on the white primer; to ensure the stability of the prepared high-temperature speckle, the prepared speckle sample is placed in a muffle furnace for baking at a temperature of 230°C for 30 minutes.

[0087] During high-temperature tensile in-situ observation tests, laser scanning confocal microscopy allows direct observation of microstructural changes and failure processes on the sample surface, but strain evolution analysis is not possible. DIC (Discrete Injection Concentration) technology, as a non-contact measurement method, enables full-field strain measurement; speckle patterns are prepared on the sample surface to facilitate pixel tracking in the DIC method.

[0088] After obtaining a material sample with random speckle patterns, the material sample is placed in an in-situ tensile observation mechanism to conduct an in-situ tensile test. This invention uses a high-temperature tensile compression system based on a set displacement rate to conduct an in-situ tensile test on a speckled material sample in a high-temperature heating furnace environment through an in-situ tensile observation mechanism. During the test, a laser scanning confocal microscope is used to observe and save the video and dynamic images of the sample in real time.

[0089] In one embodiment, such as Figure 4As shown, the in-situ tensile observation mechanism includes a tensile compression worktable and two loading mechanisms installed in the environmental cavity of the high-temperature heating furnace.

[0090] The loading mechanism is used to install speckled material samples. The first loading mechanism is fixed on the tensile compression worktable, and the other is connected to the linear driver of the high-temperature tensile compression system. The high-temperature heating furnace is mainly used to provide the test environment cavity for the high-temperature tensile compression process. The high-temperature heating furnace is equipped with a tensile compression worktable.

[0091] In one embodiment, the laser scanning confocal microscope of the in-situ tensile observation mechanism uses a purple laser VL2000DX with a wavelength of 408nm and a scanning speed of 15-120 frames per second, which can perform real-time observation and storage of dynamic images at high speed.

[0092] The high-temperature tensile compression system uses a dual-halogen lamp to reflectively heat the sample, with an effective heating area of ​​[missing information]. The loading mechanism within the heating furnace's environmental chamber is used to mount small tensile specimens. Of the two loading mechanisms, one is fixed, and the other is connected to a linear actuator. A constant load or constant displacement rate is applied to the specimen, with a drive speed ranging from 0.01 to 20 mm / min and an effective test stroke of 80 mm.

[0093] Furthermore, in one embodiment, the in-situ tensile observation mechanism further includes a test pretreatment module, which is configured to evacuate the vacuum chamber and purge it with ultra-high purity argon gas before heating after the speckled material sample is mounted on the loading mechanism to reduce the oxygen content and protect the sample surface from oxidation.

[0094] Considering that the marked area will continuously move during the tensile process, in an optional embodiment, the laser scanning confocal microscope is configured to track the marked area of ​​the material sample in real time during imaging, ensuring that the marked area remains centered in the field of view throughout the tensile process. The observation video is saved in real time, and images at corresponding time intervals are saved at set intervals. Simultaneously, the tensile curve of the test is recorded in real time. The tensile curve refers to the file record of load, displacement, and other relevant data output by the computer control system during the tensile test; the tensile curve changing over time can be obtained from the data in the file.

[0095] Taking a specific material sample as an example, the following steps are used to perform a targeted ultra-high temperature in-situ tensile test:

[0096] (1) The sample was mounted on the loading fixture by bolts using an ultra-high temperature laser scanning confocal microscope (LSCM) with tensile compression function. Before heating, the vacuum chamber was evacuated and purged with ultra-high purity argon to reduce the oxygen content (nitrogen flow rate 100 ml / min) to protect the sample surface from oxidation.

[0097] (2) Focus by adjusting the distance between the lens and the sample surface until the lens obtains a clear image; adjust the lens position to make the marked area in the center of the field of view; set the magnification appropriately and ensure that the magnification remains unchanged during the shooting process.

[0098] (3) During the test, the temperature inside the chamber was measured by thermocouples. A certain heating rate was set at the control terminal according to the experimental requirements to raise the temperature to the specified temperature. Similarly, a constant displacement rate was set at the control terminal, and the sample was stretched at a certain displacement rate at the set experimental temperature until it broke.

[0099] (4) During the experiment, speckle images of the specimen at each deformation stage were acquired in real time. Since the marked area moves continuously during the tensile process, it is necessary to track the marked area in real time during image capture. Throughout the tensile process, the microstructure evolution, crack initiation, and propagation process of the specimen surface can be observed and recorded in real time using a microscopic imaging system. During the experiment, observation videos were saved in real time, and one image was saved per second in JPG or PNG format. Simultaneously, the tensile curve was recorded in real time.

[0100] The tensile test is carried out according to the above logic until the material fractures, indicating that the test is invalid.

[0101] During the high-temperature tensile in-situ observation test, the microstructure changes and failure process on the sample surface can be directly observed using a laser scanning confocal microscope, but strain evolution analysis cannot be performed.

[0102] As a non-contact measurement method, Digital Image Correlation (DIC) technology can achieve full-field strain measurement. Furthermore, researchers can, according to experimental needs, use a deformation-strain evolution analysis module during or after the experiment to analyze some or all of the dynamic images of the testing process based on the DIC algorithm, constructing the displacement field of the speckle material sample surface and calculating the corresponding strain field. The DIC method is based on a speckle map with a certain distribution of feature points. These feature points use pixels as coordinates and pixel grayscale as information carriers. Before the correlation algorithm runs, a square sub-region of the image is selected, with the center of this sub-region being the pixel of interest. During image movement or deformation, the displacement vector at the center point of the sub-region can be obtained by tracking the position of the sub-region in the deformed image (i.e., the target image). Analyzing the displacement vectors of multiple sub-region center points constitutes the displacement field of the entire analysis area.

[0103] like Figure 5As shown, one image is used as a reference image and the other as the image to be matched. In the reference image, a rectangular sub-image of size (2M+1)×(2M+1) centered at the point to be matched (x, y) is selected. In the image to be matched, a certain search method is used, and a correlation calculation is performed according to a certain correlation function to find the sub-image centered at (x′, y′) with the largest correlation coefficient with the selected sub-image. Then, the point (x′, y′) is the corresponding point of the point (x, y) in the image to be matched.

[0104] In one embodiment, the deformation-strain evolution analysis module includes an image filtering unit and a strain analysis unit;

[0105] The image filtering unit is configured to filter material surface photographs obtained by ultra-high temperature laser scanning confocal microscope during the in-situ stretching process, and select effective speckle images whose grayscale distribution meets the set requirements.

[0106] The strain analysis unit is configured to use the DIC algorithm to calculate the selected valid speckle images, realize the matching of deformation points on the object surface, reconstruct the coordinates of the calculated points on the object surface based on the disparity data of each corresponding point, and obtain the displacement field of the object surface by comparing the coordinate changes of each point in the measurement area of ​​each deformation state. Then, the strain field of the object surface is calculated using GOM software and VIC-2D software.

[0107] Specifically, in one embodiment, the strain analysis unit uses GOM software and VIC-2D software to calculate the strain value of each pixel; the strain increment at each pixel under the loading step can be calculated by using two adjacent deformation images, and the corresponding strain distribution image and strain increment distribution image are formed by combining image processing functions.

[0108] In practical applications, the in-situ tensile process material surface failure photos obtained by ultra-high temperature laser scanning confocal microscopy (LSCM) are first screened, and high-quality speckle images with a certain grayscale distribution are selected.

[0109] This invention utilizes a digital image correlation (DIC) algorithm to analyze photographs (selecting speckle images with a certain grayscale distribution) obtained from in-situ stretching using an ultra-high temperature laser scanning confocal microscope (LSCM). This allows for the matching of deformation points on the object's surface. Based on the parallax data of each point, the coordinates of the calculated points on the object's surface are reconstructed. Furthermore, by comparing the coordinate changes of each point within the measurement area of ​​each deformation state, the displacement field of the object's surface is obtained, and the strain field of the object's surface is further calculated. By comparing the speckle images of the material surface before and after deformation and applying the correlation algorithm to obtain the full-field displacement and strain, the strain distribution and dynamic evolution process of the microstructure on the sample surface can be studied and analyzed. For example, GOM software and VIC-2D software can be used to calculate the strain value of each pixel. The strain increment at each pixel under the loading step can be calculated from two adjacent deformation images. The strain distribution image and strain increment distribution image can be obtained using the software's built-in image processing function. By comparing the speckle images of the material surface before and after deformation under external loads or other factors and applying the correlation algorithm to obtain the full-field displacement and strain, the strain distribution and dynamic evolution process of the microstructure on the sample surface can be studied and analyzed.

[0110] This invention addresses the limitation of existing SEM combined with EBSD in-situ observation techniques in studying the dynamic failure processes of ultra-high temperature (above 1200℃) materials. It employs ultra-high temperature laser scanning confocal microscopy (LSCM) combined with DIC technology to analyze the strain dynamic evolution during material deformation at ultra-high temperatures, providing an effective method for revealing the initiation and propagation mechanisms of cracks at ultra-high temperatures. This invention can be applied to the field of material failure analysis, providing reliable observational data for studying the strain dynamic evolution and crack initiation mechanisms of material deformation and failure processes under ultra-high temperature conditions.

[0111] In the analysis system for the dynamic evolution of strain in the microstructure of materials under ultra-high temperature deformation provided in this invention, each module or unit structure can operate independently or in combination according to experimental and computational requirements to achieve the corresponding technical effects.

[0112] Example 2

[0113] The above-disclosed embodiments of the present invention have described the structure of the system in detail. Based on the operating principle of the system described in any one or more of the above embodiments, the present invention also provides a method for analyzing the dynamic evolution of strain in the microstructure of materials under ultra-high temperature deformation. This method is applied to the analysis system for the dynamic evolution of strain in the microstructure of materials under ultra-high temperature deformation described in any one or more of the above embodiments. Specific embodiments are given below for detailed description.

[0114] Specifically, Figure 6 The diagram shows a flowchart illustrating the analytical method for the dynamic evolution of microstructure strain in materials under ultra-high temperature deformation provided in an embodiment of the present invention. Figure 6As shown, the method includes:

[0115] The sample preparation steps involve cutting the material to be tested into sheet-like pieces and then pre-treating it according to the testing requirements to obtain effective material samples for testing to achieve ultra-high temperature deformation tests of materials.

[0116] The experiment involves the following steps: creating high-contrast random speckles on the obtained material sample to obtain a speckled material sample; the speckles are speckled particles with sizes in the submicron / nanometer range and stable performance.

[0117] The in-situ tensile observation procedure involves conducting an in-situ tensile test on the speckled material sample within a high-temperature heating furnace environment chamber using a high-temperature tensile compression system based on a set displacement rate. During the test, a laser scanning confocal microscope is used to observe and save the video and dynamic images of the sample in real time.

[0118] The deformation strain evolution analysis steps are configured to analyze the dynamic images of the test process based on the DIC algorithm, construct the displacement field on the surface of the speckled material sample, and calculate the corresponding strain field.

[0119] Furthermore, in one embodiment, the sample preparation step includes:

[0120] The material cutting process involves cutting sheet materials of a set size from the plate using wire cutting, based on the experimental requirements of ultra-high temperature in-situ observation.

[0121] The material processing steps involve using a sandpaper grinding device to grind the cut sheet material on both sides, selecting one side as the observation surface, and using a metallographic sandpaper device to grind it step by step until the observation requirements are met; then, a marking device is used to mark the observation area on the observation surface, and the marking device is a microhardness tester.

[0122] In a preferred embodiment, the experimental speckle formation step includes:

[0123] In the primer spraying step, after ensuring that the surface of the material sample is clean and free of contaminants, a matte high-temperature primer of a set thickness is evenly sprayed onto the observation surface of the material test.

[0124] In the speckled spraying step, a high-contrast high-temperature paint with diffused and randomly distributed coating is further sprayed on the high-temperature primer.

[0125] Furthermore, the experimental speckle formation step also includes...

[0126] The sample baking process involves using a muffle furnace to bake the sprayed sample at a constant temperature for a set time, so that the speckled pattern has high-temperature stability.

[0127] Specifically, in one embodiment, the in-situ tensile observation step includes mounting the obtained speckled material test specimen on a loading mechanism of a tensile-compression stage within the environmental cavity of a high-temperature heating furnace, and conducting an in-situ tensile test under the control of a linear actuator of the high-temperature tensile-compression system. There are two loading mechanisms within the environmental cavity of the high-temperature heating furnace; the first loading mechanism is fixed to the tensile-compression stage, and the other is connected to the linear actuator of the high-temperature tensile-compression system.

[0128] The laser scanning confocal microscope of the in-situ tensile observation mechanism uses a purple laser VL2000DX with a wavelength of 408nm and a scanning speed of 15-120 frames per second.

[0129] On the other hand, in order to ensure that the state of the test sample is reliable and there is no interference from other external factors, in one embodiment, the tensile in-situ observation step also includes a test pretreatment step: after the speckled material sample is installed on the loading mechanism, before heating, the vacuum chamber is evacuated and purged with ultra-high purity argon to reduce the oxygen content and protect the sample surface from oxidation.

[0130] Furthermore, in one embodiment, the in-situ tensile observation step further includes: having the laser scanning confocal microscope track the marked area of ​​the material sample in real time during imaging, so that the marked area is always in the center of the field of view throughout the tensile process, saving the observation video in real time, saving the images at the corresponding time intervals according to the set time intervals, and recording the tensile curve in real time.

[0131] Furthermore, in a preferred embodiment, the deformation strain evolution analysis step includes:

[0132] The image screening step involves screening in-situ tensile process material surface photographs obtained by ultra-high temperature laser scanning confocal microscope, and selecting effective speckle images whose grayscale distribution meets the set requirements.

[0133] The strain analysis step involves using the DIC algorithm to calculate the selected valid speckle images, matching the deformation points on the object surface, reconstructing the coordinates of the calculated points on the object surface based on the disparity data of each corresponding point, and obtaining the displacement field of the object surface by comparing the coordinate changes of each point in the measurement area of ​​each deformation state. Then, the strain field of the object surface is calculated using GOM software and VIC-2D software.

[0134] For the foregoing method embodiments, in order to simplify the description, they are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0135] It should be noted that, in other embodiments of the present invention, the method can also combine one or more of the above embodiments to obtain a new method for dynamic evolution analysis of strain in the microstructure of materials under ultra-high temperature deformation, so as to achieve a comprehensive analysis of material failure research.

[0136] It should be noted that, based on the methods in any one or more embodiments of the present invention described above, the present invention also provides a storage medium storing program code that can implement the methods described in any one or more embodiments. When the program code is executed by the operating system, it can realize the analysis method for the dynamic evolution of strain in the microstructure of ultra-high temperature deformation of materials as described above.

[0137] It should be understood that the embodiments disclosed herein are not limited to the specific structures, processing steps, or materials disclosed herein, but should be extended to equivalent substitutions of these features as understood by those skilled in the art. It should also be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0138] The phrase "an embodiment" in the specification means that a specific feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Therefore, the phrase "an embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0139] While the embodiments disclosed in this invention are as described above, the content is merely for the purpose of facilitating understanding of the invention and is not intended to limit the invention. Any person skilled in the art to which this invention pertains may make any modifications and variations in form and detail of the implementation without departing from the spirit and scope disclosed herein; however, the scope of patent protection for this invention shall still be determined by the scope defined in the appended claims.

Claims

1. An analysis system for the dynamic evolution of strain in the microstructure of materials under ultra-high temperature deformation, characterized in that, The system includes: The sample preparation mechanism is configured to cut sheet-shaped materials to be tested and pre-treat them according to the testing requirements to obtain effective material samples for testing to achieve ultra-high temperature deformation tests of materials. The experimental speckle formation mechanism is configured to create high-contrast random speckles on the obtained material sample to obtain a speckled material sample; the speckles are speckle particles with sizes in the submicron or nanometer range and stable performance; after the speckles are prepared, a microscopic photograph of the surface to be tested is taken, and the sample image is analyzed to identify whether the distribution of nanoparticles is uniform; if the area occupied by nanoparticles in the photograph meets the set value of 30%-50% of the sample quantity, the requirements are met; if the requirements are not met, the parameters of the preparation operation are adjusted and the preparation is repeated until the prepared speckles meet the conditions. The in-situ tensile observation mechanism is configured to perform in-situ tensile testing on the speckled material sample in a high-temperature heating furnace environment cavity using a high-temperature tensile compression system based on a set displacement rate. During the test, a laser scanning confocal microscope is used to observe and save the video and dynamic images of the sample in real time. The deformation strain evolution analysis module is connected to the in-situ tensile observation mechanism and is configured to analyze the dynamic images of the test process based on the DIC algorithm, construct the displacement field of the speckle material sample surface and calculate the corresponding strain field. The in-situ tensile observation mechanism also includes a test pretreatment module, which is configured to evacuate the vacuum chamber and purge it with ultra-high purity argon gas before heating after the speckled material sample is installed on the loading mechanism to reduce the oxygen content and protect the sample surface from oxidation. The deformation-strain evolution analysis module includes an image filtering unit and a strain analysis unit; The image filtering unit is configured to filter material surface photographs obtained by ultra-high temperature laser scanning confocal microscope during the in-situ stretching process, and select effective speckle images whose grayscale distribution meets the set requirements. The strain analysis unit is configured to use the DIC algorithm to calculate the selected valid speckle images, realize the matching of deformation points on the object surface, reconstruct the coordinates of the calculated points on the object surface based on the disparity data of each corresponding point, and obtain the displacement field of the object surface by comparing the coordinate changes of each point in the measurement area of ​​each deformation state. Then, the strain field of the object surface is calculated using GOM software and VIC-2D software.

2. The system according to claim 1, characterized in that, The sample preparation mechanism includes a material cutting module and a material processing module; The material cutting module is used to cut sheet materials of a set size from the plate using wire cutting, according to the experimental requirements of ultra-high temperature in-situ observation. The material processing module is configured to use a sandpaper grinding device to grind the cut sheet material on both sides, select one side as the observation surface, and use a metallographic sandpaper device to grind it step by step until the observation requirements are met; then a marking device is used to mark the observation area on the observation surface, and the marking device is a microhardness tester.

3. The system according to claim 1, characterized in that, The experimental speckle forming mechanism includes: The primer spraying module is configured to uniformly spray a set thickness of matte high-temperature primer onto the observation surface of the material test while ensuring that the surface of the material sample is clean and free of contaminants. The speckle spraying module is configured to further spray a diffused and randomly distributed high-contrast high-temperature paint onto a high-temperature primer.

4. The system according to claim 1, characterized in that, The experimental speckle forming mechanism also includes The speckle sample baking module uses a muffle furnace to bake the material sample after spraying speckles at a constant temperature according to the set temperature and time, so that the speckles have high temperature stability.

5. The system according to claim 1, characterized in that, The in-situ tensile observation mechanism includes a tensile compression worktable and two loading mechanisms installed in the environmental cavity of a high-temperature heating furnace. The loading mechanism is used to install speckled material samples. The first loading mechanism is fixed on the tensile compression worktable, and the other is connected to the linear driver of the high-temperature tensile compression system.

6. The system according to claim 1, characterized in that, The laser scanning confocal microscope of the in-situ tensile observation mechanism uses a purple laser VL2000DX with a wavelength of 408 nm and a scanning speed of 15-120 frames per second.

7. The system according to claim 1, characterized in that, The laser scanning confocal microscope tracks the marked area of ​​the material sample in real time during imaging, ensuring that the marked area remains in the center of the field of view throughout the tensile process. It saves the observation video in real time and saves images at corresponding time intervals, while simultaneously recording the tensile curve of the test in real time.

8. A method for analyzing the dynamic evolution of strain in the microstructure of materials under ultra-high temperature deformation, characterized in that, The method is applied to the system according to any one of claims 1 to 7, and the method includes: The sample preparation steps involve cutting the material to be tested into sheet-like pieces and then pre-treating it according to the testing requirements to obtain effective material samples for testing to achieve ultra-high temperature deformation tests of materials. The experiment involves the following steps: creating high-contrast random speckles on the obtained material sample to obtain a speckled material sample; the speckles are speckled particles with sizes in the submicron or nanometer range and stable performance. The in-situ tensile observation procedure involves conducting an in-situ tensile test on the speckled material sample within a high-temperature heating furnace environment chamber using a high-temperature tensile compression system based on a set displacement rate. During the test, a laser scanning confocal microscope is used to observe and save the video and dynamic images of the sample in real time. The deformation strain evolution analysis steps are configured to analyze the dynamic images of the test process based on the DIC algorithm, construct the displacement field on the surface of the speckled material sample, and calculate the corresponding strain field.

Images