Device and method for testing surface microscopic performance of magnetic material under service condition

Abstract

The invention relates to a device and a method for testing surface microscopic performance of a magnetic material under a service condition, and belongs to the field of precise scientific instruments. The device is composed of a test loading module and an in-situ detection module. The test loading module drives a worm gear and a worm through a servo motor to drive a lead screw mechanism to achieve pulling or pressing preloading, and fatigue loading is completed in combination with a piezoelectric stack and a flexible hinge. A modularized high-temperature loading cavity and a liquid nitrogen refrigerating device are adopted to realize high or low-temperature environment construction; the position of the coil or the magnitude of current is accurately adjusted through the air cylinder to achieve accurate application of the magnetic field. The in-situ detection module carries out observation by using a behavior in-situ test method, and supports magnetic domain dynamic observation and in-situ mechanical test. According to the invention, the construction of a more complex coupling loading service condition is realized, the real service behavior of the magnetic material is more accurately simulated, a plurality of methods for observing the microscopic performance of the surface of the magnetic material are provided, and a more accurate observation means is provided for the research on the service performance of the magnetic material.

Description

Technical Field

[0001] The present invention relates to the field of precision scientific instruments, and in particular to a device and method for testing the surface microscopic properties of magnetic materials under service conditions. Background Art

[0002] Magnetic materials are increasingly used in a wide range of fields, including scientific research, medicine, industry, energy, aerospace, and information technology. Examples include magnetic resonance imaging, magnetic levitation trains, the International Nuclear Experimental Reactor (ITER), and aerospace magnetic shielding. Currently, most methods for testing magnetic material properties rely on offline testing, measuring their macroscopic magnetic properties, microscopic magnetic structure, dynamic magnetic properties, thermal magnetic properties, and other related characteristics. However, online testing and measurement of magnetic material magnetomechanical properties under varying loads remain inadequate and require further improvement.

[0003] Magnetic materials are widely used in a variety of complex operating conditions due to their unique properties. However, existing physical field simulation devices focus on simulating a single complex load, temperature, humidity, or magnetic field condition, and struggle to accurately simulate the multi-physics loading conditions experienced in real-world service. Under these complex operating conditions, changes in magnetic field intensity and direction, temperature fluctuations, and the interaction of mechanical stresses prevent existing simulations from fully capturing material failure mechanisms, such as domain wall migration, domain reversal, and demagnetization. This limits the optimization of magnetic material performance and the development of new materials.

[0004] Therefore, there is an urgent need for a method that can detect the properties of magnetic materials online and a testing device that can achieve high-low temperature, force, and magnetic high-precision coupled loading measurement of the mechanical properties of magnetic materials, which is of great significance for promoting materials science research and engineering applications. Summary of the Invention

[0005] The purpose of the present invention is to provide a device and method for testing the surface microscopic properties of magnetic materials under service conditions, which solves the technical problems of the prior art such as incomplete simulation environment and single observation means. The present invention better establishes the relationship between force, magnetism, temperature and material magnetic domains through multiple observation methods such as in-situ dynamic magnetic domain observation and in-situ observation. At the same time, the original magnetic domain testing method is innovated to achieve in-situ observation of magnetic domains. More complex multi-physical field coupling methods such as high and low temperature, electromagnetic, tensile, compression, fatigue, etc. are realized to more closely simulate the actual service conditions of the material. The device can be loaded in single or multiple parts to achieve the versatility of the device. The device can not only simulate the complex environment of magnetic materials under actual working conditions, but also provide reliable data support for the design, optimization and performance evaluation of materials.

[0006] The above-mentioned purpose of the present invention is achieved through the following technical solutions: A device for testing the surface microscopic properties of magnetic materials under service conditions employs a horizontal layout and includes an observation unit, a drive and transmission unit, a fatigue loading unit, a temperature loading unit, a magnetic field loading unit, and a specimen clamping unit. The drive and transmission unit is implemented as follows: a DC servo motor 109 outputs a constant speed and torque, which is transmitted via a gear reducer to a worm gear assembly 110. The worm gear is secured to a lead screw 113 via a set screw. Lead screw 113 transmits power via a push plate 114 to a flexible hinge 10502. A force sensor 10402 is mounted at the front end of flexible hinge 10502. The other end of force sensor 10402 is connected to an extension rod 120, which transmits the load to specimen 119 via a clamping body 10202. A baffle is mounted on the side of flexible hinge 10502. When the device reaches its limit position, the baffle triggers a limit switch assembly 111, stopping the device. The fatigue loading unit is implemented as follows: after the tensile preload is completed, the worm gear assembly 110 is self-locked to prevent loosening during loading; a piezoelectric stack 10501 is integrated into the flexible hinge 10502, and a constant displacement is generated by the piezoelectric stack 10501 to drive the flexible hinge 10502 to drive the force sensor 10402 and the clamp body 10202, thereby applying a periodic fatigue load to the sample 119; the temperature loading unit adopts a modular design and is arranged below the sample 119, which can realize rapid switching between high-temperature loading and low-temperature loading. Replacement; the magnetic field loading unit is arranged behind the clamp body 10202 to apply a controllable magnetic field to the sample 119; the sample clamping unit is connected to the extension rod 120 through a threaded structure to ensure the accurate transmission of the load; the observation unit is a magneto-optical Kerr microscope 2 and a high-temperature digital image DIC microscope 3, and the two microscopes can be replaced. The magneto-optical Kerr microscope is placed directly above the sample 119 for in-situ magnetic domain observation of the sample 119; it is replaced with a high-temperature digital image DIC microscope 3, and in-situ observation of the sample 119 is achieved by spraying speckle on the sample 119.

[0007] The observation unit includes a magneto-optical Kerr microscope 2 and a high-temperature digital image DIC microscope 3, which can realize rapid replacement of microscopes through a slide rail to achieve different observation modes; the magneto-optical Kerr microscope 2 is fixed directly above the sample 119 and is used for in-situ dynamic magnetic domain observation of the sample 119; the high-temperature digital image DIC microscope 3 is used for in-situ testing of the sample 119, by spraying speckles and combining digital image correlation method DIC to analyze the strain distribution of the sample; by switching the observation mode, the device can simultaneously meet the requirements of magnetic domain dynamic analysis and in-situ mechanical property testing, thereby improving test efficiency and functionality.

[0008] The drive and transmission unit drives the worm gear assembly 110 via a DC servo motor 109. The worm gear transmits torque to a ball screw 113, which converts rotational motion into linear motion. This ball screw drives a flexible hinge 10502 via a push plate 114. A force sensor 10402 is positioned in front of the flexible hinge 10502. The load is transmitted to the specimen 119 via an extension rod 120 housed in a bearing seat. The bearing seat is intended to prevent bending of the extension rod 120 due to its length. Synchronous or asynchronous loading can be achieved in four directions, as can individual loading in the remaining directions. This provides a wider range of loading methods for the specimen and improves the practicality of the device.

[0009] The fatigue loading unit applies force control to the DC servo motor 109. When a certain force is reached, the worm gear assembly 110 self-locks. At this point, the piezoelectric stack 10501, housed within the flexible hinge 10502, operates. A four-channel piezoelectric amplifier allows for simultaneous loading of the four piezoelectric stacks 10501, both in the same manner and in different ways. Advantages include high-precision control with nanometer-level resolution using the piezoelectric stacks 10501, fast response speed, compact structure, and high-frequency testing capabilities. Self-locking also ensures the original preload of the specimen, thereby improving the accuracy of magnetic material loading and, consequently, the reliability of observations and analytical conclusions.

[0010] The temperature loading unit is designed to place a high-temperature loading device in the center of the test apparatus. Two ceramic heating rods 10802 heat the specimen 119 through heat conduction. A heating chamber 10803 is screwed to the lower surface of the baseplate of the multi-physics field coupling test platform 1. After removing the heating chamber 10803, a low-temperature loading head 20301 can be inserted through the temperature loading hole in the center of the baseplate and placed under the specimen 119 to apply low-temperature loading to the specimen 119. This loading method allows for the flexible replacement of high and low-temperature devices, significantly improving convenience.

[0011] The magnetic field loading unit, an electromagnetic loading device placed behind the clamping body 10202, applies a precise magnetic field to the specimen 119. Two cylinders 10101 are positioned on the electromagnetic loading device. By extending and retracting the cylinders 10101, the density of the magnetic field coils 10102 can be varied, thereby changing the magnitude of the magnetic field applied to the specimen. The magnetic field magnitude can also be varied by adjusting the current flowing through the magnetic field coils 10102. This feature enhances the precision and controllability of magnetic field variations.

[0012] The size of the test device is less than 350mm*350mm*120mm to ensure that the small test device can be integrated with the microscope.

[0013] Another object of the present invention is to provide a method for testing the surface microscopic properties of magnetic materials under service conditions, comprising the following steps: a. Before each experiment, adjust the fixture back to the absolute position of the fixture zero point, so that the fixture can be accurately returned to the zero point after each experiment, which is convenient for installing the specimen; b. Install the sample into the groove of the clamping body. After clamping the sample, clear the readings of the four force sensors and four grating displacement sensors to zero. c. Perform high-temperature loading: First, turn on the water cooling system to circulate water cooling on the outside of the high-temperature cavity; set the high-temperature loading temperature and perform temperature loading; if low-temperature loading is required, the high-temperature cavity needs to be removed and the low-temperature loading head needs to be placed under the specimen; during the temperature loading process, the force sensor is kept at zero through the force control mode; d. After the temperature loading is completed, the magnetic field loading is carried out, and the position of the cylinder is controlled according to different requirements to control the magnetic field size; e. According to different purposes, different loading modes such as uniaxial tension, biaxial tension, uniaxial fatigue and biaxial fatigue can be realized at high temperature; f. By adjusting the position of the microscope, the required microscope can be replaced to perform in-situ magnetic domain dynamic observation or in-situ mechanical property observation of the sample.

[0014] The beneficial effects of the present invention are: (1) The test device can be integrated with a magneto-optical Kerr microscope and a high-temperature digital image DIC microscope. The microscope can be repositioned via a guide rail to achieve different observation methods. Multiple observation methods can realize in-situ dynamic observation of magnetic domain changes on the surface of magnetic materials and in-situ mechanical property testing of magnetic materials. The relationship between force, magnetism, temperature and the magnetic domains of the material can be better established.

[0015] (2) The synchronous control of four motors can realize single or double axis tension and compression, tension and compression in different proportions, and the use of piezoelectric ceramics to realize the coupling of various loading conditions such as single or double axis fatigue and fatigue in different proportions.

[0016] (3) It can achieve coupling of high and low temperature, tensile and compressive fatigue, and strong magnetism, and better simulate the complex service conditions of magnetic materials.

[0017] (4) The temperature loading module can realize the replacement of high temperature loading module and low temperature loading module.

[0018] (5) Using piezoelectric ceramics to achieve fatigue loading is more accurate than motor fatigue loading, has a compact structure, and is easy to arrange.

[0019] (6) The test accuracy is high, the structure is relatively simple, and it is easy to implement.

[0020] In summary, the present invention provides effective testing and multiple observation methods for performance testing of magnetic materials under complex service conditions, and has strong practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings described herein are used to provide further understanding of the present invention and constitute a part of this application. The illustrative examples of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0022] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 Schematic diagram of the overall structure of the multi-physics field coupling test device of the present invention; Figure 3 It is a structural schematic diagram of the transmission mechanism of the present invention; Figure 4 This is a schematic diagram of the fatigue loading structure of the present invention; Figure 5 It is a structural schematic diagram of the magnetic field loading of the present invention; Figure 6 This is a schematic structural diagram of high-temperature loading of the present invention; Figure 7 This is a schematic diagram of the structure of low-temperature loading of the present invention; Figure 8 is an exploded view of the clamping assembly of the present invention; Figure 9 This is a schematic structural diagram of the mechanical signal detection unit of the present invention; Figure 10 Schematic diagram of the structure of the deformation signal detection unit of the present invention.

[0023] In the figure: 1. Multi-physics field coupling test platform; 101. Magnetic field loading assembly; 10101. Cylinder; 10102. Magnetic field coil; 10103. Coil compression plate; 10104. Magnetic field support block; 102. Clamping assembly; 10201. Fixture upper cover; 10202. Clamp body; 103. Extension rod support bearing seat; 104. Force sensor assembly; 10401. Locking nut; 10402. Force sensor; 105. Fatigue loading assembly; 10501. Piezoelectric stack; 10502. Flexible hinge; 106. Deformation measurement assembly; 10601. Reading head; 10602. Reading head fixing plate; 10603. Grating scale; 10604. Grating scale fixing plate; 107. Sliding assembly; 1 0701, support plate slider; 10702, bottom plate slider; 108, high-temperature loading assembly; 10801, heating chamber upper cover; 10802, heating rod; 10803, heating chamber; 109, DC servo motor; 110, worm gear assembly; 111, limit switch assembly; 112, screw fixing seat; 113, screw; 114, push plate; 115, screw nut; 116, support plate; 117, screw support seat; 118, motor fixing plate; 119, specimen; 120, extension rod; 2, magneto-optical Kerr microscope; 201, high-speed camera; 202, objective lens; 203, low-temperature loading assembly; 20301, low-temperature loading head; 3, high-temperature digital image DIC microscope; 301, CCD camera. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0025] See also Figures 1 to 10As shown, the device and method for testing the surface microscopic properties of magnetic materials under service conditions of the present invention are composed of a test loading module and an in-situ detection module: the test loading module drives the worm gear to drive the screw mechanism through a servo motor to achieve tensile or compressive preloading, and combines the piezoelectric stack and the flexible hinge to complete fatigue loading; a modular high-temperature loading cavity and a liquid nitrogen refrigeration device are used to achieve high or low temperature environment construction; the cylinder accurately adjusts the coil position or adjusts the current size to achieve precise application of the magnetic field. The in-situ detection module uses a behavioral in-situ test method for observation, and supports dynamic observation of magnetic domains and in-situ mechanical testing. The present invention realizes the construction of more complex coupled loading service conditions, more accurately simulates the real service behavior of magnetic materials, provides a variety of methods for observing the surface microscopic properties of magnetic materials, and provides a more accurate observation means for the study of the service performance of magnetic materials.

[0026] See also Figures 1 to 3 As shown, the surface microscopic performance testing device for magnetic materials under service conditions of the present invention adopts a horizontal arrangement as the overall structure, including an observation unit, a drive and transmission unit, a fatigue loading unit, a temperature loading unit, a magnetic field loading unit, and a fixture clamping unit. The observation unit is composed of a magneto-optical Kerr microscope 2 and a high-temperature digital image DIC microscope 3, which can be replaced by a guide rail. First, the multi-physical field coupling test device 1 is installed on the base plate through a screw connection, and the objective lens 202 is aligned with the center of the sample 119. The high-speed camera 201 is used to perform in-situ dynamic magnetic domain observation or the CCD camera 301 is used to perform in-situ observation. The drive and transmission unit includes a DC servo motor 109, fixed to a motor mounting plate 118. It is driven by a worm gear assembly 110 after deceleration and torque increase, driving a ball screw 113 for transmission. The ends of the ball screw 113 are fixed to a screw mounting base 112 and a screw support base 117. By driving a screw nut 115, the rotational motion is converted into linear motion and transmitted to a push plate 114. Both sides of the push plate 114 are fixed to the bottom plate slider 10702 of the sliding assembly 107 to prevent the generation of an overturning moment. The push plate 114 is connected to a flexible hinge 10502 via screws, transmitting power to the flexible hinge 10502. The ends of the flexible hinge 10502 are also connected to a support plate slider 10701 via screws. The support plate slider 10701 is mounted on a support plate 116 to prevent the flexible hinge 10505 from generating an overturning moment. Flexible hinge 10502 is threadedly connected to locking nut 10401 and force sensor 10402. The other end of force sensor 10402 is threadedly attached to extension rod 120 of extension rod support bearing seat 103. A stud at the other end of extension rod 120 is connected to clamp body 10202 to load specimen 119.

[0027] See also Figure 4Figure 1 shows the structure of the fatigue loading unit. A flexible hinge 10502 is connected to a support plate slider 10701 on the support plate 116. A piezoelectric stack 10501 is placed within the flexible hinge 10502. The other end of the stack is secured with a set screw to ensure highly accurate and stable displacement output. The piezoelectric stack 10501 drives the flexible hinge 10502, transferring the fatigue load to the specimen 119 via the force sensor 10402, the extension rod 120, and the clamping body 10202.

[0028] See also Figure 5 As shown in the figure, it is a structural diagram of magnetic field loading. The magnetic field support block 10104 is connected to the base plate by four hexagon socket screws. The magnetic field loading assembly 101 is installed on the magnetic field support block 10104 by screws. Two cylinders 10101 are placed on the side wall of the magnetic field loading assembly 101. By controlling the extension and contraction of the cylinder 10101 with high precision, the coil compression plate 10103 is driven to compress the magnetic field coil 10102, so that the size of the magnetic field acting on the sample 119 can be adjusted as needed.

[0029] See also Figures 6 and 7 As shown, the high-temperature loading module, the heating chamber 10803 is connected and fixed to the base plate by screws, and the side walls of the heating chamber 10803 have mutually perpendicular mounting holes, and the two heating rods 10802 are arranged vertically to achieve uniform heating of the specimen 119. The upper cover plate 10801 of the heating chamber is connected to the heating chamber 10803 by screws, and a heat-insulating material is affixed inside to reduce heat conduction to the outside world, so that the entire instrument is basically operated at room temperature. There is a high-temperature window in the center of the upper cover plate 10801 of the heating chamber to achieve observation of the specimen 119 during high-temperature loading. The low-temperature loading module, the multi-physics field coupling test platform 1 is removed, and then the high-temperature loading assembly 108 is removed, and the low-temperature loading head 20301 of the low-temperature loading assembly 203 is placed under the specimen 119 through the center hole of the base plate. The multi-physics field coupling test platform 1 cooperates with the low-temperature loading device to achieve low-temperature loading of the specimen 119.

[0030] See also Figure 8 As shown, the extension rod 120 is connected to the clamp body 10202 of the clamping assembly 102, the sample 119 is placed in the clamp body 10202, and the clamp upper cover 10201 is connected to the clamp body 10202 by screws.

[0031] See also Figures 9 and 10A locking nut 10401 is installed on the force sensor 10402 of the force sensor assembly 104, and then connected to the front end thread of the flexible hinge 10502 of the fatigue loading assembly 105. When the clamp body 10202 is horizontal with the base plate, the locking nut 10401 is tightened to ensure that the clamp body 10202 can remain horizontal without deflection. The deformation detection unit is as follows: the grating scale fixing plate 10604 of the deformation measurement assembly 106 is fixed to the side wall of the flexible hinge 10502, the grating scale 10603 is fixed to the grating scale fixing plate, the reading head fixing plate 10602 is connected to the support plate 116 by screws, and the reading head 10601 is connected to the reading head fixing plate 10602 by screws, so that a constant distance is maintained between the reading head 10601 and the grating scale 10603, so that the reading head 10601 can accurately obtain the displacement, and indirectly measure the deformation of the sample 119 by measuring the displacement of the flexible hinge 10502.

[0032] The surface microscopic performance testing device of the magnetic material under service conditions of the present invention adopts four independent loading modules, and ensures synchronous stretching or multi-form stretching of the four stretching ends by issuing commands simultaneously by the controller. The four piezoelectric stacks are connected in parallel to better ensure synchronous fatigue loading, or different fatigue loadings are achieved through the piezoelectric controller, which is more conducive to in-situ dynamic magnetic domain observation or in-situ observation of the center of the sample 119.

[0033] See also Figures 1 to 10 As shown, the invented method for testing the surface microscopic properties of magnetic materials under service conditions requires calibration and verification of the four force sensors 10402 and the deformation measurement assembly 106 before installing the test instrument. The instrument is then installed and debugged, and the absolute position of the original position is recorded. After each experiment, the clamp must be returned to its original position to facilitate the clamping of the next test specimen. The specific steps are as follows: a. Before each experiment, adjust the fixture back to the absolute position of the fixture zero point, so that the fixture can be accurately returned to the zero point after each experiment, which is convenient for installing the specimen; b. Install the sample into the groove of the clamping body. After clamping the sample, clear the readings of the four force sensors and four grating displacement sensors to zero. c. Perform high-temperature loading: First, turn on the water cooling system and circulate water cooling around the outside of the high-temperature cavity. Set the high-temperature loading temperature and perform temperature loading. To achieve low-temperature loading, remove the high-temperature cavity and place the low-temperature loading head under the specimen. During the temperature loading process, the tensile force sensor is kept at zero through force control mode. d. After the temperature loading is completed, the magnetic field loading is carried out, and the position of the cylinder is controlled according to different requirements to control the magnetic field size; e. According to different experimental purposes, different loading modes such as uniaxial tension, biaxial tension, uniaxial fatigue, and biaxial fatigue can be achieved at high temperature; f. By adjusting the position of the microscope, the required microscope can be replaced to perform on-site magnetic domain observation or in-situ observation of the sample.

[0034] Magnetic material performance testing methods are crucial for evaluating their quality. Currently, magnetic materials are often subjected to complex service conditions (high and low temperatures, strong magnetism, fatigue, tension, compression, and biaxial loading). This method can better simulate these complex service conditions and enable in-situ dynamic magnetic domain observation under a magneto-optical Kerr microscope or in-situ observation under a high-temperature digital imaging DIC microscope, which is of great significance for the performance research of magnetic materials.

[0035] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements to the present invention are intended to fall within the scope of protection of the present invention.

Claims

1. A device for testing the surface microscopic properties of magnetic materials under service conditions, characterized by: The invention adopts a horizontal structural layout, including an observation unit, a driving and transmission unit, a fatigue loading unit, a temperature loading unit, a magnetic field loading unit and a sample clamping unit; the driving and transmission unit is: a DC servo motor (109) outputs a constant speed and torque, which is transmitted to a worm gear assembly (110) through a gear reduction box, the worm gear is fixedly connected to a lead screw (113), and the lead screw (113) transmits power to a flexible hinge (10502) through a push plate (114); a force sensor (10402) is installed at the front end of the flexible hinge (10502), and the other end of the force sensor (10402) is connected to an extension rod (120), and transmits the load to the sample (119) through a clamping body (10202); the fatigue loading unit is: a flexible hinge (10502) A piezoelectric stack (10501) is integrated inside, and a constant displacement is generated by the piezoelectric stack (10501) to drive the flexible hinge (10502) with the power sensor (10402) and the clamp body (10202), thereby applying a periodic fatigue load to the sample (119); the temperature loading unit adopts a modular design and is arranged below the sample (119) to achieve rapid switching between high-temperature loading and low-temperature loading; the magnetic field loading unit is arranged behind the clamp body (10202) to apply a controllable magnetic field to the sample (119); the sample clamping unit is connected to the extension rod (120) to ensure the transmission of the load; the observation unit includes two interchangeable microscopes, a magneto-optical Kerr microscope (2) and a high-temperature digital image DIC microscope (3).

2. The device for testing surface microscopic properties of magnetic materials under service conditions according to claim 1, characterized in that: The observation unit comprises a magneto-optical Kerr microscope (2) and a high-temperature digital image DIC microscope (3), which respectively realize rapid replacement of the microscopes through slide rails to realize different observation modes; the magneto-optical Kerr microscope (2) is fixed directly above the sample (119) to perform in-situ dynamic magnetic domain observation on the sample (119); the high-temperature digital image DIC microscope (3) performs in-situ testing on the sample 119, and analyzes the strain distribution of the sample by spraying speckles and combining digital image correlation method DIC; by switching the observation mode, the dynamic analysis of magnetic domains and in-situ mechanical property testing are simultaneously satisfied, thereby improving the test efficiency and functionality.

3. The device for testing surface microscopic properties of magnetic materials under service conditions according to claim 1, characterized in that: The driving and transmission unit is as follows: a DC servo motor (109) drives the worm gear assembly (110) to move, the worm gear transmits torque to the ball screw (113), the screw converts the rotational motion into linear motion through the push plate (114) to drive the flexible hinge (10502), a force sensor (10402) is arranged in front of the flexible hinge (10502), and the load is transmitted to the specimen (119) through the extension rod (120) placed in the bearing seat, thereby realizing synchronous or asynchronous loading in four directions, and also realizing individual loading.

4. The device for testing surface microscopic properties of magnetic materials under service conditions according to claim 1, characterized in that: The fatigue loading unit is as follows: force control is applied to the DC servo motor (109), and when the expected load is reached, the worm gear assembly (110) is self-locked; at this time, the piezoelectric stack (10501) placed in the flexible hinge (10502) is put into operation, and the four piezoelectric stacks (10501) are driven by a four-channel piezoelectric amplifier to load in the same manner and in different manners at the same time.

5. The device for testing surface microscopic properties of magnetic materials under service conditions according to claim 1, characterized in that: The temperature loading unit is: two ceramic heating rods (10802) heat the sample (119) by heat conduction; the heating chamber (10803) is fixed to the lower surface of the bottom plate of the multi-physics field coupling test platform (1) by screws, and after the heating chamber (10803) is removed, the low-temperature loading head (20301) is inserted from the temperature loading hole in the center of the bottom plate and placed under the sample (119) to achieve low-temperature loading of the sample.

6. The device for testing surface microscopic properties of magnetic materials under service conditions according to claim 1, characterized in that: The magnetic field loading unit is to place an electromagnetic loading device behind the clamp body (10202) to apply a precise magnetic field to the sample (119); two cylinders (10101) are arranged on the electromagnetic loading device, and the density of the magnetic field coil (10102) is changed by the expansion and contraction of the cylinder (10101), thereby changing the size of the magnetic field applied to the sample; at the same time, the magnetic size is changed by changing the size of the current passed into the magnetic field coil (10102).

7. The device for testing surface microscopic properties of magnetic materials under service conditions according to claim 1, characterized in that: The test device has a size of less than 350mm×350mm×120mm and is integrated with a microscope.

8. A method for testing the surface microscopic properties of magnetic materials under service conditions, characterized by: The steps include: a. Before each experiment, adjust the fixture back to the absolute position of the fixture zero point, so that the fixture can be accurately returned to the zero point after each experiment, which is convenient for installing the specimen; b. Install the sample into the groove of the clamping body. After clamping the sample, clear the readings of the four force sensors and four grating displacement sensors to zero. c. Perform high-temperature loading: First, turn on the water cooling system to circulate water cooling on the outside of the high-temperature cavity; set the high-temperature loading temperature and perform temperature loading; if low-temperature loading is required, the high-temperature cavity needs to be removed and the low-temperature loading head needs to be placed under the specimen; during the temperature loading process, the force sensor is kept at zero through the force control mode; d. After the temperature loading is completed, the magnetic field loading is carried out, and the position of the cylinder is controlled according to different requirements to control the magnetic field size; e. According to different purposes, different loading modes such as uniaxial tension, biaxial tension, uniaxial fatigue and biaxial fatigue can be realized at high temperature; f. By adjusting the position of the microscope, the required microscope can be replaced to perform in-situ magnetic domain dynamic observation or in-situ mechanical property observation of the sample.

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