Device for quasi-in-situ testing of microstructure evolution of metal sample

Abstract

The invention provides a device for quasi-in-situ testing of microstructure evolution of a metal sample, the device comprises a bridge, one end of the bridge is used for being electrically connected with one end of the metal sample, and the other end of the bridge is used for being electrically connected with the other end of the metal sample, the electric bridge and the metal sample together form an annular closed loop; the electromagnetic induction coil is used for enabling the annular closed loop to generate induction current, and the induction current enables the temperature of the metal sample to rise and microstructure evolution to occur. The electromagnetic induction efficiency can be remarkably improved, eddy current distribution is simplified, quasi-in-situ analysis is facilitated, the influence rule of eddy current on microstructure evolution can be more accurately reflected, and the action mechanism of the eddy current can be determined.

Description

Technical Field

[0001] The present disclosure relates to the field of testing the microstructure evolution of metal specimens, and particularly to an apparatus for quasi-in-situ testing of the microstructure evolution of metal specimens. Background Art

[0002] The microstructure of metal materials has a decisive influence on their macroscopic properties. The microstructure includes characteristics such as grain morphology, second-phase distribution, grain orientation, texture, etc. During metal processing, heat treatment, etc., the microstructure will evolve, and the study of these evolution laws is of great significance for optimizing the properties of metal materials and improving their application value.

[0003] Currently, the research on the microstructure evolution law of metal specimens is mainly achieved by comparing the microstructure characteristics before and after electromagnetic induction treatment and electromagnetic induction-assisted plastic deformation. Commonly used characterization methods include electron backscatter diffraction, scanning electron microscopy, etc. The specific process is as follows: First, electromagnetic induction treatment or electromagnetic induction-assisted plastic deformation is performed on the metal specimen, and then the observation regions are intercepted from different specimens, and equipment such as electron backscatter diffraction and scanning electron microscopy is used to analyze the microstructure characteristics of these regions, such as measuring the recrystallization fraction, texture, second-phase morphology and distribution, etc.

[0004] However, there are some problems with the existing testing methods. First, since generally the observation regions for microstructure characterization are taken from different specimens and there are differences in the initial microstructure, comparing the microstructure characteristics of specimens after electromagnetic induction treatment or electromagnetic induction-assisted plastic deformation under different conditions cannot accurately reflect the influence law of eddy current on microstructure evolution, and it is difficult to accurately reveal the action mechanism of induced eddy current. Second, there is a strong alternating magnetic field around the coil during electromagnetic induction, and the excitation of induced eddy current is not selective. All metals close to the coil will generate induced eddy current in the alternating magnetic field and the temperature will rise. This makes it difficult to directly combine the electromagnetic induction device with the scanning electron microscope for in-situ observation of the electromagnetic induction process, and it is necessary to separate and alternate the electromagnetic induction process and the microstructure characterization process of the same specimen, that is, to perform quasi-in-situ characterization. Moreover, the eddy current distribution inside the specimen is complex and difficult to predict, and it is difficult to correspond to the evolution of the microstructure. This brings difficulties to analyzing the influence law of the eddy current direction on the microstructure evolution. Summary of the Invention

[0005] The present disclosure provides an apparatus for quasi-in-situ testing of the microstructure evolution of metal specimens; it can significantly improve the electromagnetic induction efficiency, simplify the eddy current distribution, facilitate quasi-in-situ analysis, and can more accurately reflect the influence law of eddy current on microstructure evolution and determine its action mechanism.

[0006] The technical solution of the present disclosure is realized as follows: An embodiment of the present disclosure provides a device for quasi-in-situ testing of the microstructure evolution of a metal specimen. The device includes: A bridge, one end of the bridge is used to be electrically connected to one end of the metal specimen, and the other end of the bridge is used to be electrically connected to the other end of the metal specimen, so that the bridge and the metal specimen together form a closed loop. An electromagnetic induction coil, which is used to generate an induced current in the closed loop, and the induced current causes the temperature of the metal specimen to rise and the microstructure to evolve.

[0007] In some alternative examples, the bridge clamps the metal specimen between one end and the other end of the bridge through elastic deformation, so that the metal specimen is fixed in the device.

[0008] In some alternative examples, a first slot is formed at one end of the bridge, and a second slot is formed at the other end of the bridge. The first slot is used to closely cooperate with one end of the metal specimen, and the second slot is used to closely cooperate with the other end of the metal specimen, so that the metal specimen is fixed in the device.

[0009] In some alternative examples, the device further includes an enclosure, which is used to enclose the metal specimen and is formed with an air inlet and an air outlet. The air inlet is used to allow a protective gas to enter the interior of the enclosure, and the air outlet is used to discharge the gas inside the enclosure, so as to prevent the metal specimen from undergoing an undesired chemical reaction during the temperature rise.

[0010] In some alternative examples, the enclosure is further formed with a sampling opening, which is used to sample the gas inside the enclosure.

[0011] In some alternative examples, the device further includes an infrared thermometer outside the enclosure. The enclosure is inlaid with infrared glass, and the infrared thermometer is used to measure the temperature of the metal specimen through the infrared glass.

[0012] In some alternative examples, the enclosure includes a lifting base and a cover body. When the lifting base is in the raised position, the lifting base and the cover body together form a closed space that encloses the metal specimen. When the lifting base is in the lowered position, a gap is formed between the lifting base and the cover body through which the metal specimen can pass.

[0013] In some alternative examples, the device further includes a specimen stage, the specimen stage is formed with a fixing portion in the shape of an arcuate cylinder, and the bridge is fixed to the fixing portion in a manner surrounding the cylindrical surface of the fixing portion, such that one end and the other end of the bridge face the rectangular surface of the fixing portion and the rectangular surface is spaced apart from the bridge.

[0014] In some alternative examples, the fixing portion is formed with a longitudinal depression radially opposed to the rectangular surface, and a protrusion matching the depression is formed in the middle section of the bridge.

[0015] In some alternative examples, the bridge includes a first conductive chuck, a second conductive chuck, and a flexible wire. The first conductive chuck is used to clamp one end of the metal specimen, the second conductive chuck is used to clamp the other end of the metal specimen, and the flexible wire connects the first conductive chuck and the second conductive chuck, such that when the metal specimen is stretched, the bridge will not affect the stretching result.

[0016] The present disclosure provides a device for quasi-in-situ testing of the microstructure evolution of a metal specimen. By connecting a bridge with the metal specimen to form a closed loop, the electromagnetic induction efficiency is significantly improved. This design not only enables the induced current to flow along a circular path, reducing energy loss, but also can quickly heat up and accelerate the microstructure evolution, enhancing the experimental efficiency. At the same time, the closed loop simplifies the eddy current distribution inside the specimen, making its path clear and single, facilitating quasi-in-situ analysis. Additionally, in traditional electromagnetic induction, the eddy current distribution is complex and difficult to predict. However, by simplifying the eddy current distribution, the present disclosure can more accurately reflect the influence law of eddy currents on the microstructure evolution, clearly observe and analyze the evolution process of the microstructure under different eddy current conditions, thereby determining the action mechanism of eddy currents and providing a guarantee for precisely controlling the experimental conditions. Description of the Drawings

[0017] Figure 1 It is a schematic structural diagram of the device for quasi-in-situ testing of the microstructure evolution of a metal specimen provided by an embodiment of the present disclosure.

[0018] Figure 2 It is a schematic structural diagram of the specimen stage of the device for quasi-in-situ testing of the microstructure evolution of a metal specimen provided by an embodiment of the present disclosure and the bridge fixed to the specimen stage.

[0019] Figure 3 It is a schematic structural diagram of the bridge of the device for quasi-in-situ testing of the microstructure evolution of a metal specimen provided by another embodiment of the present disclosure.

[0020] Figure 4 It is a schematic diagram of the electron microscope scanning area of the metal specimen provided by the present disclosure.

[0021] Figure 5 Schematic structural diagram of a device including a flexible wire bridge for quasi-in-situ testing of the microstructure evolution of a metal specimen provided by another embodiment of the present disclosure.

[0022] Figure 6 Schematic structural diagram of the combination of a device including a flexible wire bridge for quasi-in-situ testing of the microstructure evolution of a metal specimen provided by another embodiment of the present disclosure and a universal testing machine. Detailed implementation manners

[0023] Next, the technical solutions in the present disclosure will be clearly and completely described in conjunction with the accompanying drawings in the present disclosure.

[0024] In the prior art, as a commonly used method for regulating the microstructure of metal materials, electromagnetic induction treatment can effectively achieve processes such as recrystallization annealing, solid solution, and aging of metal materials, but there are many challenges in the study of the microstructure evolution law. During the electromagnetic induction process, the alternating magnetic field around the coil will excite induced eddy currents in all metals close to the coil, resulting in temperature rise. This non-selective excitation of induced eddy currents makes it difficult for the electromagnetic induction device to be directly combined with microscopic characterization equipment such as a scanning electron microscope, thus making it impossible to achieve in-situ observation of the electromagnetic induction process. Therefore, current research usually needs to separate the electromagnetic induction process from the microstructure characterization process, that is, adopt the method of quasi-in-situ characterization.

[0025] However, in the prior art, the eddy current distribution inside the specimen is complex and difficult to predict, which makes it difficult to accurately analyze the relationship between the eddy current direction and the microstructure evolution. In addition, since the specimen is in a high-temperature state during the electromagnetic induction process, chemically active metal materials (such as aluminum alloys) are prone to oxidation and form oxide films, thus affecting the accuracy and reliability of subsequent microstructure characterization.

[0026] In view of the above problems, the present disclosure proposes a device for quasi-in-situ testing of the microstructure evolution of a metal specimen. Through innovative design, the device realizes the quasi-in-situ characterization of the microstructure evolution of the metal specimen. Specifically, referring to Figure 1 and Figure 2 , an embodiment of the present disclosure provides a device 1 for quasi-in-situ testing of the microstructure evolution of a metal specimen S. The device 1 may include a bridge 10 and an electromagnetic induction coil 20.

[0027] One end 101 of the bridge 10 is used to be electrically connected to one end S1 of the metal specimen S, and the other end 102 of the bridge 10 is used to be electrically connected to the other end S2 of the metal specimen S, so that the bridge 10 and the metal specimen S together form a circular closed loop 10S.

[0028] The electromagnetic induction coil 20 is used to generate an induced current in the annular closed loop 10S, and the induced current causes the temperature of the metal specimen S to rise and the microstructure to evolve.

[0029] In the present disclosure, the bridge 10 is connected to the metal specimen S to form an annular closed loop 10S. This structural design significantly improves the electromagnetic induction efficiency. The annular closed loop 10S can more effectively guide the flow of the induced current, reduce energy loss, so that under the same electromagnetic induction conditions, the metal specimen S can be heated up faster and the microstructure evolution process can be accelerated. This not only improves the experimental efficiency but also provides a guarantee for accurately controlling the experimental conditions. The design of the annular closed loop 10S makes the induced eddy current flow along an annular path, thus simplifying the eddy current distribution inside the specimen S. In traditional electromagnetic induction treatment, the eddy current distribution inside the specimen S is complex and difficult to predict, which brings difficulties to analyzing the relationship between the eddy current direction and the microstructure evolution. However, through the design of the bridge 10 and the annular closed loop 10S in the present disclosure, the path of the induced eddy current is made more clear and single, facilitating quasi-in-situ analysis. Since the annular closed loop 10S simplifies the eddy current distribution, the present disclosure can more accurately reflect the influence law of the eddy current on the microstructure evolution. During the electromagnetic induction process, the direction and intensity of the induced eddy current play a key role in the microstructure evolution of the metal specimen S. By simplifying the eddy current distribution, the present disclosure can more clearly observe and analyze the evolution process of the microstructure under different eddy current conditions, thereby determining the action mechanism of the eddy current.

[0030] In some embodiments of the present disclosure, referring to Figure 2 , the bridge 10 can clamp the metal specimen S between one end 101 and the other end 102 of the bridge 10 through elastic deformation, as shown in Figure 2 , so that the metal specimen S is fixed in the device 1, as can be easily understood by referring to Figure 1 .

[0031] During the quasi-in-situ test, the metal specimen S needs to be repeatedly switched between electromagnetic induction treatment and microstructure characterization. That is, the metal specimen S needs to be electrically connected to the bridge 10 to cause microstructure evolution, and at the same time needs to be separated from the bridge 10 for testing using equipment such as a scanning electron microscope. In the present disclosure, the bridge 10 clamps the metal specimen S through elastic deformation, making the connection and separation processes simple and efficient. Specifically, the bridge 10 is designed as a structure that can be elastically deformed. When the metal specimen S is placed in the bridge 10, the notch of the bridge 10 opens to both sides and undergoes slight elastic deformation, and then rebounds to clamp the metal specimen S. This design not only simplifies the operation steps but also reduces the risk of poor contact or damage caused by frequent connection and separation. During the electromagnetic induction process, the metal specimen S is subjected to the Lorentz force, which causes it to displace, thereby affecting the stability and accuracy of the experiment. Through the elastic deformation design of the bridge 10, the present disclosure realizes reliable fixation of the metal specimen S. The elastic deformation of the bridge 10 can clamp the metal specimen S, which can resist the action of the Lorentz force during the electromagnetic induction process and prevent the metal specimen S from displacing. This design effectively avoids experimental errors caused by the Lorentz force and ensures the stability of the electromagnetic induction treatment and microstructure characterization processes.

[0032] More specifically, the end faces of one end 101 and the other end 102 of the bridge 10 can be polished to ensure good contact and prevent arcing and local high temperature on the contact surface.

[0033] In some embodiments of the present disclosure, referring to Figure 3 , a first slot 10A can be formed at one end 101 of the bridge 10, and a second slot 10B can be formed at the other end 102 of the bridge 10. The first slot 10A is used for close fitting with one end S1 of the metal specimen S, and the second slot 10B is used for close fitting with the other end S2 of the metal specimen S, as shown in Figure 3 to keep the metal specimen S fixed in the device 1, as can be easily understood by referring to Figure 1 . In this case, one end S1 of the metal specimen S can be in the shape of a thin sheet matching the first slot 10A for fitting with the first slot 10A, and the other end S2 of the metal specimen S can be in the shape of a thin sheet matching the second slot 10B for fitting with the second slot 10B, or as shown in Figure 3 , the metal specimen S can be in the shape of a thin sheet as a whole.

[0034] In materials science experiments, the shapes and sizes of metal specimens S are diverse. Especially for thin sheet specimens, due to their small thickness and large surface area, they are prone to deformation or sliding during the clamping process, making it difficult to achieve reliable fixation. In this disclosure, a first slot 10A is provided at one end 101 of the bridge 10, and a second slot 10B is provided at the other end 102, so that both ends S1 and S2 of the thin sheet specimen can closely cooperate with the slots. This design not only solves the problem of difficult clamping of thin sheet specimens but also ensures the stability of the specimen during the electromagnetic induction treatment process. Through the slot design, this disclosure also enables the metal specimen S to quickly and accurately cooperate with the bridge 10, simplifies the connection and separation steps, not only improves the experimental efficiency but also reduces the risk of damage or poor contact of the metal specimen S caused by frequent operations. Additionally, it can also achieve reliable fixation of the metal specimen S. Even under the action of the Lorentz force during the electromagnetic induction process, the metal specimen S and the bridge 10 can remain stable, avoiding experimental errors caused by displacement, ensuring the stability of the electromagnetic induction treatment and microstructure characterization processes, and improving the reliability of experimental results.

[0035] In some embodiments of the present disclosure, referring to Figure 1 , the device 1 may further include an enclosure 30. The enclosure 30 is used to enclose the metal specimen S and is formed with an air inlet opening 30A and an air outlet opening 30B. The air inlet opening 30A is used to allow a protective gas to enter the interior of the enclosure 30, and the air outlet opening 30B is used to exhaust the gas inside the enclosure 30 to prevent the metal specimen S from undergoing unwanted chemical reactions during the temperature increase. Additionally, as shown in Figure 1 , the air inlet opening 30A and the air outlet opening 30B can be configured as quick-connect fittings for air pipes to facilitate connection to the air inlet pipe and the air outlet pipe. Additionally, although not shown in the drawings, it can be understood that the air inlet pipe can be connected to a protective gas source, such as a gas cylinder filled with a protective gas. A pressure reducing valve can be provided on the air inlet pipe.

[0036] During the electromagnetic induction treatment process, the temperature of the metal specimen S will increase significantly. Metal materials with relatively active chemical properties (such as aluminum alloys) are prone to react with oxygen in the air to form an oxide film. This oxide film will seriously affect the subsequent microstructure characterization. For example, it will reduce the resolution of electron backscatter diffraction characterization and the accuracy of electron microscope analysis. The present disclosure forms an inert gas environment inside the enclosure 30 by providing the enclosure 30 and introducing a protective gas (such as argon or nitrogen), thereby effectively preventing the oxidation of the surface of the metal specimen S. This design ensures the chemical stability of the specimen during the high-temperature treatment process and provides a high-quality sample for the subsequent microstructure characterization. By preventing the oxidation of the surface of the metal specimen S, the present disclosure significantly improves the accuracy of the microstructure characterization. The presence of the oxide film will lead to a reduction in the resolution of electron backscatter diffraction characterization because the oxide layer will interfere with the interaction between the electron beam and the specimen surface and affect the quality of the diffraction signal. In addition, the oxide film will also lead to a reduction in the contrast of the electron microscope image, affecting the observation and analysis of the microstructure. The present disclosure ensures that the specimen surface remains clean through the protective gas environment, thereby improving the accuracy and reliability of characterization techniques such as electron backscatter diffraction and electron microscopy.

[0037] In some embodiments of the present disclosure, referring to Figure 1 , the enclosure 30 may also be formed with a sampling opening 30C for sampling the gas inside the enclosure 30. Additionally, as shown in Figure 1 , the sampling opening 30C may also be configured as a quick-connect fitting for an air pipe to facilitate connection to a sampling air pipe. Additionally, although not shown in the drawings, it can be understood that the sampling air pipe may be connected to a sampler.

[0038] By providing the sampling opening 30C on the enclosure 30, it is convenient to sample the gas inside the enclosure 30. This design allows experimenters to monitor the gas composition during the electromagnetic induction treatment to ensure that an inert gas environment is always maintained inside the enclosure 30. For example, by connecting a gas analyzer (such as an oxygen analyzer), the oxygen content inside the enclosure 30 can be detected in real time. Once the oxygen content exceeds the set threshold, the gas flow rate can be adjusted in a timely manner or the protective gas can be replaced, thereby effectively preventing the occurrence of oxidation reactions. Conducting experiments in a controlled gas environment can ensure that the conditions of each experiment are highly consistent. By monitoring the gas composition in real time and making timely adjustments, experimental errors caused by changes in the gas environment can be avoided. Such highly consistent experimental conditions contribute to improving the repeatability of experimental results and providing reliable experimental data support for scientific research and industrial applications.

[0039] In some embodiments of the present disclosure, referring to Figure 1, the apparatus 1 may further include an infrared thermometer 40 outside the enclosure 30. The enclosure 30 may be inlaid with an infrared glass 301. The infrared thermometer 40 is configured to measure the temperature of the metal specimen S through the infrared glass 301.

[0040] The infrared glass 301 has an extremely low infrared absorption rate, which means that during the measurement process, infrared radiation energy can efficiently pass through the glass and transfer from the metal specimen S to the infrared thermometer 40. The low absorption rate characteristic ensures that the infrared thermometer 40 can accurately capture the infrared signal emitted by the specimen surface, thereby providing high-precision temperature measurement results. This high-precision temperature measurement is particularly important for experiments that require strict temperature control, and can significantly improve the reliability and repeatability of the experiments. The infrared thermometer 40 performs non-contact temperature measurement through the infrared glass 301, avoiding problems that may be caused by contact temperature measurement, such as interference of the temperature measurement element with the specimen, measurement delay caused by thermal inertia, and errors caused by poor contact. Non-contact temperature measurement not only improves the measurement response speed but also reduces potential damage to the specimen surface.

[0041] In some embodiments of the present disclosure, referring to Figure 1 , the enclosure 30 may include a lifting base 31 and a housing 32. As shown in Figure 1 , when the lifting base 31 is in the raised position, the lifting base 31 and the housing 32 together form an enclosed space that encloses the metal specimen S. As can be easily understood although not shown in the drawings, when the lifting base 31 is in the lowered position, a gap is formed between the lifting base 31 and the housing 32 through which the metal specimen S can pass.

[0042] The cooperative design of the lifting base 31 and the housing 32 enables the metal specimen S to quickly switch between electromagnetic induction treatment and microstructure characterization. When the lifting base 31 is in the lowered position, a gap is formed between the base and the housing, and the metal specimen S can be easily taken out or put in through this gap. This design avoids complex disassembly and installation processes and significantly improves the experimental efficiency.

[0043] A rubber pad may be installed at the bottom edge of the housing 32 to reduce air leakage.

[0044] The material of the lifting base 31 may be insulating and heat-resistant materials such as silica and alumina.

[0045] The material of the housing 32 may be insulating and transparent materials such as heat-resistant glass and plexiglass to facilitate observing the internal situation of the housing 32 during the experiment.

[0046] In some embodiments of the present disclosure, referring to Figure 2 and combining with Figure 1, the apparatus 1 may further include a specimen stage 50. The specimen stage 50 is formed with a fixing portion 51 having an arcuate cylindrical shape. Here, the "arcuate cylindrical shape" refers to the shape obtained after a part of a complete cylinder is cut off by a plane parallel to its longitudinal central axis. Such a shape has a cylindrical surface 51T and a rectangular surface 51S as shown in Figure 2 . The bridge 10 is fixed to the fixing portion 51 in a manner surrounding the cylindrical surface 51T of the fixing portion 51, such that one end 101 and the other end 102 of the bridge 10 face the rectangular surface 51S of the fixing portion 51 and the rectangular surface 51S is spaced apart from the bridge 10. Thus, when the metal specimen S is fixed to the bridge 10, the metal specimen S will be spaced apart from the rectangular surface 51S.

[0047] In this way, it is ensured that the metal specimen S can be stably fixed on the specimen stage 50 under the action of the bridge 10, avoiding the displacement of the metal specimen S during the electromagnetic induction treatment process, thereby improving the reliability of the experiment. By designing the fixing portion 51 of the specimen stage 50, the metal specimen S only contacts the bridge 10 and does not contact the specimen stage 50 or other components. This design simplifies the heat dissipation path of the metal specimen S and avoids the increase in thermal resistance caused by additional contact. The design of the specimen stage 50 keeps the metal specimen S spaced from the rectangular surface 51S of the fixing portion 51, avoiding direct heat conduction between the metal specimen S and the specimen stage 50. This design reduces the influence of the specimen stage 50 on the temperature of the metal specimen S, ensuring that the temperature measured by the infrared thermometer 40 can more accurately reflect the temperature of the metal specimen S itself. This precise temperature control is crucial for studying the evolution law of the microstructure.

[0048] As shown in Figure 2 , the specimen stage 50 may further be formed with a through hole, and the through hole can cooperate with a pin shaft provided on a lifting base 31 as shown in Figure 1 , thereby fixing the specimen stage 50. The materials of the specimen stage 50 and the pin shaft may also be insulating and heat-resistant materials such as silica and alumina.

[0049] In some embodiments of the present disclosure, referring to Figure 2 , the fixing portion 51 may be formed with a longitudinal recess 51R radially opposed to the rectangular surface 51S, and a protrusion 10P matching the recess 51R may be formed in the middle section of the bridge 10.

[0050] Through the cooperation of the protrusion 10P and the recess 51R, the bridge 10 can be quickly and accurately positioned on the fixing part 51. This design simplifies the installation process of the bridge 10, enabling the experimenter to complete the assembly of the bridge 10 and the fixing part 51 within a short time, reducing errors and time waste caused by manual adjustment. This precise positioning mechanism is particularly suitable for experimental scenarios that require frequent specimen replacement, significantly improving the experimental efficiency. The cooperation between the recess 51R and the protrusion 10P ensures the stability of the bridge 10 on the fixing part 51. During the electromagnetic induction process, the metal specimen S will be affected by electromagnetic force and thermal expansion, and this design can effectively prevent the bridge 10 from shifting or loosening due to external forces. The stable fixing method of the bridge 10 not only improves the safety of the experiment but also ensures the reliable clamping of the metal specimen S during the experiment, thereby improving the reliability of the experimental results.

[0051] In some embodiments of the present disclosure, the material of the bridge 10 can be the same as that of the metal specimen S.

[0052] When the material of the bridge 10 is the same as that of the metal specimen S, the bridge 10 and the specimen S exhibit similar electromagnetic characteristics during the electromagnetic induction process. This design enables the induced current to be more evenly distributed between the bridge 10 and the specimen S, thereby simplifying the eddy current distribution inside the specimen. Compared with combinations of different materials, the bridge 10 and the specimen S of the same material can reduce the eddy current complexity caused by material differences, making the eddy current distribution more regular, and thus more accurately observing and analyzing the evolution law of the microstructure under the action of eddy currents. This design reduces experimental errors caused by material differences, enabling the experimental results to more truly reflect the influence of eddy currents on the evolution of the microstructure.

[0053] In some embodiments of the present disclosure, refer to Figure 1 , the device 1 may further include: an electromagnetic induction sub-machine 60, an electromagnetic induction main machine 70, and a temperature control system 80.

[0054] The electromagnetic induction coil 20 can be installed on the electromagnetic induction sub-machine 60 and is located directly above the bridge 10 and the metal specimen S, as shown in Figure 1 .

[0055] The temperature control system 80 can preset the upper and lower temperature limits. By comparing the temperature measured by the infrared thermometer 40 with the preset upper and lower temperature limits, the temperature control system 80 realizes precise temperature control of the metal specimen S. Specifically: when the temperature measured by the infrared thermometer 40 is lower than the preset lower temperature limit, the temperature control system 80 controls the electromagnetic induction main unit 70 and the electromagnetic induction auxiliary unit 60 to start and increases the electromagnetic induction current, so that the temperature of the metal specimen S rises rapidly until it exceeds the preset lower temperature limit; when the temperature measured by the infrared thermometer 40 is higher than the preset upper temperature limit, the temperature control system 80 controls to reduce the electromagnetic induction current until the electromagnetic induction main unit 70 and the electromagnetic induction auxiliary unit 60 are turned off, so that the temperature of the metal specimen S decreases. Through the closed-loop control of the infrared thermometer 40 and the temperature control system 80, the start and stop of the electromagnetic induction main unit 70 and the electromagnetic induction auxiliary unit 60 and the precise regulation of the magnitude of the electromagnetic induction current are realized, so as to ensure that the metal specimen S always remains within the set temperature range during the whole experiment process, and the accurate temperature control of the specimen is realized.

[0056] Based on the device 1 according to the foregoing embodiments of the present disclosure, the specific process of quasi-in-situ testing the microstructure evolution of the metal specimen S is as follows: First, a cuboid-shaped metal specimen S is cut by wire cutting, and the observation plane of the metal specimen S is polished until it reaches a mirror-like and scratch-free effect. At the same time, the planes on the left and right sides of the metal specimen S in contact with the bridge 10 are polished to be flat and smooth to ensure the reliability of subsequent connections; then, a 500μm×500μm square area is selected on the observation plane of the metal specimen S as the electron microscope scanning area, and microhardness indentations are made at the two vertices of the upper left corner and the lower right corner of this area using a microhardness tester. The hardness indentations are diamond-shaped, and its two diagonals are along the horizontal and vertical directions respectively. Vertical and horizontal extension lines are made through the bottom vertex and the top vertex of the hardness indentation, and the square area surrounded by the intersection of the extension lines is the electron microscope scanning area, such as Figure 4As shown in ; then, the observation plane of the metal sample S is electropolished or ion polished to remove the surface stress layer. For 2 series aluminum alloys, the electropolishing can use anhydrous ethanol perchloric acid (1:9) solution, the voltage is set to 30V, the processing time is 15s, and during ion polishing, the ion gun beam energy is set to 6kV, the thinning angle is 10°, and the bombardment time is 30min; then, the metal sample S is placed in the scanning electron microscope sample chamber, and the secondary electron image and electron backscattered diffraction image are taken in the preset electron microscope scanning area, and the energy dispersion spectrum and electron backscattered diffraction analysis and characterization are performed to obtain the grain morphology, second phase distribution, grain orientation, and texture of the sample observation plane. The metal sample S is taken out from the scanning electron microscope sample chamber, the lifting base 31 is lowered, and then the metal sample S is clamped on the bridge 10 with the observation plane facing outward. Subsequently, the bridge 10 and the metal sample S are installed on the sample table 50, and the lifting base 31 is raised until the lifting base 31 is tightly fitted with the rubber pad at the bottom edge of the cover body 32, thereby forming a closed space. The oxygen analyzer and the vacuum pump connected to the outlet end of the sampling air pipe are turned on, the gas cylinder switch is turned on, the pressure reducing valve connected to the inlet end of the air inlet opening 30A is turned on, and protective gas is introduced into the closed cover 30. The pressure reducing valve is adjusted to a gas flow rate of about 5L / min, and the oxygen analyzer reading is observed. Wait for the closed cover to be closed. When the oxygen content of the gas inside the cover 30 is lower than 1000ppm, adjust the pressure reducing valve to reduce the gas flow until the oxygen content is stable; align the infrared thermometer 40 with the observation plane of the metal sample S, ensure that the infrared thermometer 40 and the metal sample S are separated by the infrared glass 301 to ensure the accuracy of temperature measurement, set the target temperature in the temperature control system 80, and start the electromagnetic induction process. The temperature control system 80 controls the start and stop of the electromagnetic induction main machine 70 and the electromagnetic induction auxiliary machine 60 and the electromagnetic induction current by comparing the temperature measured by the infrared thermometer 40 with the preset temperature upper limit and temperature lower limit, so as to achieve accurate temperature control of the metal sample S; during the entire experiment, the oxygen analyzer is used to monitor the temperature in real time. Control the oxygen content of the gas inside the closed cover 30. If the oxygen content rises above 1000ppm, slowly increase the flow rate of protective gas until the oxygen content begins to decrease. When the oxygen content drops below 1000ppm, slowly reduce the flow rate of protective gas until the oxygen content stabilizes. After the target processing time is reached, stop the electromagnetic induction processing, wait for the metal sample S and the bridge 10 to cool naturally, and after the temperature of the metal sample S drops to 25°C, close the pressure reducing valve and gas cylinder switch connected to the air inlet end of the air inlet opening 30A, lower the lifting base 31, and take out the metal sample S. Repeat the above steps until the quasi-in-situ characterization of the microstructural evolution of the metal sample during the electromagnetic induction processing is completed.

[0057] In some embodiments of the present disclosure, see Figure 5, the bridge 10 may include a first conductive chuck 101H, a second conductive chuck 102H, and a flexible wire 10W. The first conductive chuck 101H is used to clamp one end S1 of the metal specimen S, and the second conductive chuck 102H is used to clamp the other end S2 of the metal specimen S. The flexible wire 10W connects the first conductive chuck 101H and the second conductive chuck 102H, so that when the metal specimen S is stretched, the bridge 10 will not affect the stretching result.

[0058] When the metal specimen S is stretched, the design of the flexible wire 10W ensures that the bridge 10 will not affect the stretching result. The shape of the flexible wire 10W is adjustable, which can make the shape of the looped closed circuit 10S similar to that of the electromagnetic induction coil 20, while allowing the metal specimen S to freely deform during the stretching process without affecting the test of its mechanical properties. Through the looped closed circuit 10S formed by the bridge 10 and the metal specimen S, the present disclosure can also improve the electromagnetic induction efficiency, accurately control the experimental conditions, simplify the eddy current distribution inside the specimen S, facilitate the quasi-in-situ analysis, and more accurately reflect the influence law of eddy current on the microstructure evolution and determine its action mechanism while the metal specimen S is being stretched.

[0059] Of course, the flexible wire 10W also needs to have a certain stiffness to maintain a looped closed circuit 10S with a certain area together with the metal specimen S under the action of the Lorentz force.

[0060] See Figure 5 and Figure 6 , according to the present disclosure, the device 1 can also be integrated on a universal testing machine 100 to realize the stretching of the metal specimen S, and perform electromagnetic induction treatment on the metal specimen S while stretching, so as to test the microstructure evolution of the metal specimen S. In this case, circular holes are respectively opened in the middle of the top surface and the bottom surface of the closed cover 30 to allow the upper connecting column 101 and the lower connecting column 102 of the universal testing machine 100 to pass through, so that the upper chuck 103 and the lower chuck 104 of the universal testing machine 100 can move up and down to clamp the metal specimen S, and the bridge 10 including the first conductive chuck 101H, the second conductive chuck 102H, and the flexible wire 10W can form a looped closed circuit 10S together with the metal specimen S. In this way, the shape of the bridge 10 is adjustable to make the shape of the looped closed circuit 10S similar to that of the electromagnetic induction coil 20, improving the electromagnetic induction efficiency. The temperature measurement position of the infrared thermometer 40 is selected as the center of the gauge section of the metal specimen S to accurately measure the temperature change of the metal specimen S during the stretching process.

[0061] Based on the device 1 according to the foregoing embodiments of the present disclosure, the specific process of quasi-in-situ testing of the microstructure evolution of the metal specimen S during the stretching of the metal specimen S assisted by electromagnetic induction is as follows: Cut the metal specimen S by wire cutting, and polish the outer surface of the gauge section of the metal specimen S until it reaches a mirror-like and scratch-free effect. At the same time, perform a smooth and clean polishing treatment on the surfaces of the clamping ends of the metal specimen S that come into contact with the first conductive chuck 101H and the second conductive chuck 102H to ensure the reliability of subsequent connections; Select a square area of 500μm×500μm on the surface of the gauge section of the metal specimen S as the electron microscope scanning area. Use a microhardness tester to make hardness indentations at the two vertices of the upper left corner and the lower right corner of this area. The hardness indentations are diamond-shaped, and its two diagonals are along the horizontal and vertical directions respectively. Draw vertical and horizontal extension lines through the bottom vertex and the top vertex of the hardness indentation. The square area surrounded by the intersection of the extension lines is the electron microscope scanning area, such as in Figure 4As shown in the figure; the surface of the gauge section is electropolished or ion polished to remove the surface stress layer. For 2 series aluminum alloys, electropolishing can be performed using a perchloric acid anhydrous ethanol (1:9) solution, the voltage is set to 30V, and the processing time is 15s; during ion polishing, the ion gun beam energy is set to 6kV, the thinning angle is 10°, and the bombardment time is 30min; the metal sample S is placed in the scanning electron microscope sample chamber, and the secondary electron image and backscattered electron image are taken in the preset electron microscope scanning area, and the energy dispersion spectrum and electron backscattered diffraction and other analysis and characterization are performed to obtain the sample observation plane electron microscope scanning area The metal sample S is taken out from the scanning electron microscope sample chamber, the lifting base 31 of the device is lowered, and the metal sample S is clamped between the upper chuck 103 and the lower chuck 104 of the universal testing machine 100, and then the first conductive chuck 101H and the second conductive chuck 102H are clamped on the upper and lower clamping ends of the metal sample S, and 10W is used to connect the first conductive chuck 101H and the second conductive chuck 102H to form a circular closed loop; the uniaxial tensile test program is set to determine the deformation amount and deformation of a single electromagnetic induction assisted stretching. 1. Turn on the oxygen analyzer and the vacuum pump connected to the outlet end of the sampling air pipe, turn on the gas cylinder switch, open the pressure reducing valve connected to the inlet end of the air inlet pipe, introduce protective gas into the closed cover 30, adjust the pressure reducing valve to a gas flow rate of about 5L / min, observe the oxygen analyzer reading, when the oxygen content of the gas inside the closed cover 30 is lower than 1000ppm, adjust the pressure reducing valve to reduce the gas flow rate until the oxygen content is stable; align the infrared thermometer 40 with the center of the S gauge length section of the metal sample, and ensure that the infrared thermometer 40 and the S gauge length section of the metal sample are separated by the infrared glass 301 to ensure the accuracy of the temperature measurement. To ensure the accuracy of the test, set the target temperature in the temperature control system 80 and start the electromagnetic induction treatment. After the temperature of the temperature measurement area of ​​the metal sample S rises to the target temperature, start the uniaxial stretching test program and start the electromagnetic induction assisted stretching. During the experiment, the oxygen content of the gas inside the closed cover 30 is monitored by an oxygen analyzer. If the oxygen content rises above 1000ppm, the flow rate of the protective gas is slowly increased until the oxygen content begins to decrease. When the oxygen content drops below 1000ppm, the flow rate of the protective gas is slowly reduced until the oxygen content stabilizes. After the electromagnetic induction assisted stretching is completed, the electromagnetic induction treatment is stopped and the metal sample S is allowed to cool naturally. After the sample temperature drops to 25°C, the pressure reducing valve and the gas cylinder switch connected to the air inlet end of the air inlet pipe are closed, the lifting base 31 is lowered, and the metal sample S is taken out. Repeat the above steps until the quasi-in-situ characterization of the evolution of the sample microstructure during the electromagnetic induction assisted stretching process is completed.

[0062] It should be noted that the technical solutions described in the present disclosure can be combined arbitrarily without conflict.

[0063] As described above, it is only the specific implementation manner of the present disclosure. However, the protection scope of the present disclosure is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present disclosure can easily think of changes or substitutions, which should all be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims described above.

Claims

1. A device for quasi-in-situ testing of microstructural evolution of metal specimens, characterized in that: The device comprises: An electric bridge, one end of which is used to be electrically connected to one end of the metal sample, and the other end of which is used to be electrically connected to the other end of the metal sample, so that the electric bridge and the metal sample together form a ring-shaped closed loop; The electromagnetic induction coil is used to generate an induced current in the annular closed loop, and the induced current causes the temperature of the metal sample to increase and cause microstructure evolution.

2. The device for quasi-in-situ testing of microstructure evolution of metal specimens according to claim 1, characterized in that: The electric bridge clamps the metal sample between one end of the electric bridge and the other end of the electric bridge through elastic deformation, so that the metal sample is kept fixed in the device.

3. The device for quasi-in-situ testing of microstructure evolution of metal specimens according to claim 2, characterized in that: A first slot is formed at one end of the bridge, and a second slot is formed at the other end of the bridge. The first slot is used to tightly fit with one end of the metal sample, and the second slot is used to tightly fit with the other end of the metal sample to keep the metal sample fixed in the device.

4. The device for quasi-in-situ testing of microstructure evolution of metal specimens according to any one of claims 1 to 3, characterized in that: The device also includes a closed cover, which is used to close the metal sample and is formed with an air inlet opening and an exhaust opening. The air inlet opening is used to allow protective gas to enter the interior of the closed cover, and the exhaust opening is used to exhaust the gas inside the closed cover to avoid undesirable chemical reactions of the metal sample during temperature increase.

5. The device for quasi-in-situ testing of microstructure evolution of metal specimens according to claim 4, characterized in that: The enclosed cover is also formed with a sampling opening, and the sampling opening is used to sample the gas inside the enclosed cover.

6. The device for quasi-in-situ testing of microstructure evolution of metal specimens according to claim 4, characterized in that: The device further comprises an infrared thermometer outside the closed cover, the closed cover is inlaid with infrared glass, and the infrared thermometer is used to measure the temperature of the metal sample through the infrared glass.

7. The device for quasi-in-situ testing of microstructure evolution of metal specimens according to claim 4, characterized in that: The closed cover includes a lifting base and a cover body. When the lifting base is in a raised position, the lifting base and the cover body together constitute a closed space that encloses the metal sample. When the lifting base is in a lowered position, a gap is formed between the lifting base and the cover body through which the metal sample can pass.

8. The device for quasi-in-situ testing of microstructure evolution of metal specimens according to claim 2 or 3, characterized in that: The device also includes a sample table, which is formed with a fixed part in the shape of an arcuate cylinder, and the bridge is fixed to the fixed part in a manner of surrounding the cylindrical surface of the fixed part, so that one end and the other end of the bridge are opposite to the rectangular surface of the fixed part and the rectangular surface is spaced apart from the bridge.

9. The device for quasi-in-situ testing of microstructure evolution of metal specimens according to claim 8, characterized in that: The fixing portion is formed with a longitudinal recess radially opposite to the rectangular surface, and the middle section of the bridge is formed with a protrusion matching the recess.

10. The device for quasi-in-situ testing of microstructure evolution of metal specimens according to claim 1, characterized in that: The electric bridge includes a first conductive chuck, a second conductive chuck and a flexible wire. The first conductive chuck is used to clamp one end of the metal sample, and the second conductive chuck is used to clamp the other end of the metal sample. The flexible wire connects the first conductive chuck and the second conductive chuck, so that when the metal sample is stretched, the electric bridge will not affect the stretching result.

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