A metal matrix composite fiber ejection test device and test method

Abstract

The present invention belongs to the field of micro-nanomechanical test technology, and relates to a metal matrix composite fiber ejection test device and test method. The test device includes symmetrical clamping jaws, a cylindrical sample placement platform, a hand-adjusting ring, an angle adjustment base, and a fixed base. The device and test method proposed by the present invention are suitable for fiber ejection and push-in tests of metal matrix composite samples with different diameters and cross-sectional shapes. The test sample can be repeatedly installed and disassembled without damage, avoiding contamination of the sample and the sample table by glue fixation and mechanical damage caused during the sample disassembly process. The sample can be reused and can then be used for subsequent microstructure analysis. At the same time, the clamping jaws clamp the sample perpendicularly to the plane of the sample, avoiding the shear force introduced by the sample fixation, and providing a solid foundation for accurately measuring the interface shear strength, interface friction, and interface bonding strength of the metal matrix composite material.

Description

Technical Field

[0001] The invention belongs to the technical field of micro-nanomechanical testing and relates to a metal-based composite material fiber ejection testing device and a testing method. Background Art

[0002] Continuous fiber-reinforced metal matrix composites utilize high-strength, high-modulus, low-density fibers as reinforcements, composited with a corresponding metal matrix. They are lightweight, have high specific strength and stiffness, and exhibit excellent high-temperature resistance, fatigue resistance, and corrosion resistance, offering broad application prospects in aviation, aerospace, automotive, and electronics fields. The interface is a crucial component unique to composite materials, and the fiber / matrix interface plays a key role in determining the performance of composite materials. Interfacial shear strength is an important parameter for measuring the performance of the fiber / matrix interface. Currently, the main methods for testing the interfacial shear strength of composite materials include fiber pullout, microdroplet debonding, single fiber breakage, and fiber ejection. Due to differences in sample preparation, experimental techniques, and microscopic model simplification, the interfacial shear strength values ​​obtained using different test methods vary. Eliminating interfering factors in the test method to ensure that the results are closer to the true interfacial shear strength is an important issue that urgently needs to be addressed in the study of the interfacial strength of continuous fiber-reinforced metal matrix composites.

[0003] Both the fiber pulling method and the droplet debonding method are applicable to resin-based composite materials. For metal-based composite materials, the sample preparation technology for the fiber pull-out test is complex, and the test measurement results are highly dispersed due to factors such as the fiber embedding length and the fiber exposed length measurement accuracy. The droplet debonding test requires the matrix to be transparent and is not applicable to metal-based composite materials. When the fiber ejection test is performed using a nanoindenter, the sample can be cut from the actual composite material, and an in-situ test can be performed on the real metal-based composite material. Compared with other methods, the results obtained are closer to the actual interface shear strength. Conventional nanoindenters are not equipped with a dedicated fiber ejection test platform. Existing devices usually use one or several rectangular grooves with a width much smaller than the sample diameter and a length greater than the sample diameter to set up on the platform surface. The sample is fixed on the platform, the fiber position corresponding to the groove area is determined, and then the fiber is pushed out with a diamond flat indenter. At present, there are several problems in the process of using nanoindenters for fiber ejection tests: (1) The sample fixing method causes contamination to the sample or introduces additional radial force at the interface between the fiber and the matrix. The common method is to use liquid glue or paraffin to stick the test piece on the platform groove. The sample for metal-based composite testing is usually a disc-shaped sample with a diameter of about 5mm. During the fixing process, it is very easy for the fibers at the corresponding position of the groove to be stained with glue, causing sample contamination and affecting the accuracy of the test results. At the same time, mechanical removal of the sample with tweezers or blades will damage the sample and leave glue residue. Soaking and separating with acetone cannot completely remove the residual colloid, resulting in the scrapping of the sample and the inability to conduct further analysis of the microstructure of the test area. The fixing method of setting clamping blocks around the sample and applying radial force to support the sample will increase the shear force on all fiber and matrix interfaces in the sample for fiber-reinforced composites, resulting in test data errors. (2) The test area is small, and it is impossible to perform fiber ejection test at the original position while observing and determining the area of ​​interest. For the groove platform, the test range of the sample is limited to the area corresponding to the groove width, and it is impossible to test any interesting position in the sample. Moreover, due to the small size of the test piece, the number of fibers that can be tested within the groove range is very limited. (3) It is impossible to achieve free positioning test on the sample surface. The test platform does not have a rotation function, and manual placement of the platform will inevitably result in errors with the system coordinate system, making it impossible to accurately position the fiber using the sample reference coordinate system.

[0004] The present invention proposes a metal matrix composite fiber ejection test device and test method for nanoindentation, which effectively solves the problems encountered in the fiber ejection test of continuous fiber reinforced metal matrix composite materials. Moreover, the device is very convenient to load and unload during the test and can be reused for testing, greatly improving the test accuracy and efficiency. Summary of the Invention

[0005] The present invention proposes a metal-based composite fiber ejection test device and test method for nanoindentation, which are used to fix samples during fiber ejection tests. This device solves the problems of sample contamination and damage, introduction of additional stress, small test sample size, and inability to accurately position the sample caused by the fixation method, thereby ensuring the accuracy and flexibility of the test.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A nano-indentation metal matrix composite fiber ejection test device comprises a symmetrical clamping jaw 1, a cylindrical sample placement platform 2, a hand-adjusting ring 3, an angle-adjusting base 4, and a fixed base 5. A circular groove 8 is provided at the center of the end face of the cylindrical sample placement platform 2. The symmetrical clamping jaw 1 is installed in the through groove symmetrically provided on the cylindrical sample placement platform 2. The clamping end of the symmetrical clamping jaw 1 is approximately a trapezoidal body. The outer sides of the two clamping ends are rounded rectangles, and the inner sides are arcs concentric with the groove 8. The arc at the bottom of the clamping end close to the platform 2 has the same radius as the groove 8. The plane where the upper arc is located is parallel to the bottom surface. The bottom angle of the arc side of the trapezoid is 45 °; The cylindrical sample placement platform 2 is connected by steps 19 and 20 on the angle adjustment base 4 and bolt fasteners 21; a magnet 16 is placed at the center of the fixed base 5 and connected by a wedge-shaped bolt fastener 17, and the angle adjustment base 4 is connected to the magnetic force it receives via the step 18 on the fixed base 5; the manual adjustment ring 3 and the cylindrical sample placement platform 2 are threadedly connected, and a reverse groove 15 is provided at the lower part of the manual adjustment ring 3, and the circular ring piece 14 is stuck in the groove. The symmetrical claws 1 and the circular ring piece 14 are fixedly connected by a spring 13; a long pin 12 is placed in the middle of the spring, and the length of the pin is consistent with the length of the spring in the relaxed state;

[0008] The circular groove 8 is located at the center of the cylindrical sample placement platform 2, and the diameter of the groove is 2 mm to 5 mm.

[0009] In the clamped state, the height of the symmetrical clamping claws 1 above the cylindrical sample placement platform 2 is 0.5 mm to 1.5 mm.

[0010] The fixed base 5 and the angle adjustment base 4 are made of martensitic stainless steel, which is a ferromagnetic material. The symmetrical claws 1, the cylindrical sample placement platform 2, and the manual adjustment ring 3 are made of austenitic stainless steel.

[0011] The surface of the cylindrical sample placement platform 2 is respectively marked with marking lines 6 for centering circular samples and marking lines 7 for centering square samples, as well as vertical cross marks 22 for unifying the sample coordinate system and the test system coordinate system.

[0012] The surface of the hand-adjusting ring 3 is processed with anti-slip threads; the angle adjustment base 4 is provided with angle engraved lines 9 with an interval of 1° from 0° to 360°; the fixed base 5 is provided with four evenly distributed fixing bolt holes 11, and a 0° angle marking line 10 is engraved along the diameter direction of the base.

[0013] A testing method for a metal matrix composite fiber ejection test device comprises the following steps:

[0014] 1) Prepare a sample with two parallel end faces and end faces perpendicular to the fiber length direction, with a thickness of 0.1 mm to 0.7 mm;

[0015] 2) Select the high-load module of the nanoindenter and install the conical flat indenter;

[0016] 3) Perform air pressure calibration on the indentation axis;

[0017] 4) Calibrate the relative position of the needle tip and the optical microscope: Install the aluminum standard sample on the nanoindenter test platform, make a single indentation or a group of indentations on the aluminum standard sample, and then find the indentation under the nanoindenter optical microscope. Check whether the center of the X-axis and Y-axis cross-marking lines at the center of the optical microscope field of view coincide with the set indentation position. If there is any deviation, adjust them until they are completely aligned.

[0018] 5) Place the sample on the sample placement platform. For regularly shaped samples, use the centering mark to align the sample's X and Y axes with the coordinate system of the test device platform. Place the area where the fibers to be ejected are located above the circular groove 8. Rotate the manual adjustment ring 3 clockwise to move the two jaws 1 downward, clamping the sample edge and securing the sample to be tested.

[0019] 6) Fix the test device fixed base 5 on the nanoindenter test platform by adsorption or bolts;

[0020] 7) In the optical microscope observation interface of the nanoindenter, focus the sample surface, set the working area boundary, and set the test range for the ejection test according to the position of the clamping jaws, that is, the working area of ​​the nanoindenter;

[0021] 8) In the optical microscope observation interface, observe the overall morphology of the sample in the working area, select the fiber to be tested for ejection, and adjust the X and Y axes of the nanoindenter test platform and the rotation angle of the angle adjustment base to make the center of the target fiber cross section coincide with the center of the X and Y axis intersection mark line at the center of the nanoindenter optical microscope field of view;

[0022] 9) In the indentation module of the nanoindenter, select the displacement control mode and the trapezoidal loading function. The loading curve includes: linear loading section - load holding section - linear unloading section. Set the maximum displacement, loading time, load holding time, and unloading time. Start the test. You can set multiple fiber ejection positions at the same time and record the coordinates.

[0023] 10) After the test, starting from the first set position, use the analysis module of the nanoindenter software to obtain the force-displacement curve, and use the in-situ imaging function of the nanoindenter to obtain information such as the length of the ejected fiber and the deformation of the matrix near the fiber;

[0024] 11) Rotate the manual adjustment ring 3 counterclockwise to move the two claws 1 upwards, remove the sample from the cylindrical sample placement platform 2 with tweezers, and place it into the sample box.

[0025] The conical flat indenter used in step 2) has a plane diameter of 50 μm; the load of the high-load module is 100 mN to 30 N.

[0026] The air pressure calibration of the indentation axis in step 3) should be performed before each test after the specimen is replaced.

[0027] The sample is a fiber-reinforced metal matrix composite material, and the sample is a circular, oval, square, rectangular or irregular sheet. The test plane is the cross section of the composite sample perpendicular to the fiber length direction. The sample thickness is 0.1mm to 0.5mm, and the fiber diameter is 50μm to 150μm. Compared with the existing technology.

[0028] The beneficial effects of the present invention are:

[0029] 1. The present invention provides a metal matrix composite fiber ejection test device and test method for a nanoindenter. By utilizing a clamping structure of clamping claws and a hand-adjustable ring, the test sample can be repeatedly installed and disassembled without damage, thus avoiding contamination of the sample and the sample stage by glue fixation and mechanical damage caused during sample disassembly. The sample can be reused and can then be used for subsequent microstructure analysis, greatly improving work efficiency. At the same time, the clamping claws clamp the sample perpendicularly to the plane, thus avoiding the shear force introduced by sample fixation.

[0030] 2. The manual adjustment ring clamping structure is composed of a spring, a long pin, a circular ring and a reverse groove. Each part is connected and affects each other, ensuring the overall coordination of the clamping claw when fixing the specimen, and avoiding the problem of local overload and deformation of the specimen caused by installation and disassembly.

[0031] 3. The relative position of the clamping claw and the circular groove is used to determine the test area within the specimen where the fiber ejection test can be performed. Within a large range, it is possible to observe the different fiber characteristics of the test section while arbitrarily selecting the location of interest for ejection test.

[0032] 4. The platform surface is marked with a centering mark. For circular and rectangular specimens, the mark and the vertical crosshairs on the nanoindenter test screen can be used to unify the sample coordinate system with the test system coordinate system. For samples of any shape, the sample placement platform rotates by rotating the angle adjustment base, achieving rotational motion of the specimen to unify the sample coordinate system with the nanoindentation test system coordinate system. This allows testing in multiple directions and at any specified location on the specimen surface.

[0033] 5. The fixture and testing method provided by the present invention are suitable for fiber ejection and push-in tests of metal matrix composite samples with different fiber diameters and cross-sectional shapes, providing a solid foundation for accurately measuring the interface shear strength, interface friction, and interface bonding strength of metal matrix composites. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a side view of the fiber ejection test device;

[0035] Figure 2 It is an oblique view of the fiber ejection test device;

[0036] Figure 3 yes Figure 1 Sectional view of the AA section plane;

[0037] Figure 4 It is a front view of one jaw of the symmetrical jaw 1 and a cross-sectional view along the BB direction. DETAILED DESCRIPTION

[0038] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0039] like Figures 1-4As shown, a metal matrix composite fiber ejection test device for nano indentation includes symmetrical clamping jaws 1, a cylindrical sample placement platform 2, a hand adjustment ring 3, an angle adjustment base 4 and a fixed base 5; a circular groove 8 is provided at the center of the end face of the cylindrical sample placement platform 2, and the groove diameter is 2mm to 5mm; the symmetrical clamping jaws 1 are installed in the through grooves symmetrically arranged on the cylindrical sample placement platform 2, and the clamping ends of the symmetrical clamping jaws 1 are approximately trapezoidal, with the outer sides of the two clamping ends being rounded rectangles and the inner sides being arcs concentric with the grooves 8. The arc at the bottom of the clamping end close to the platform 2 has the same radius as the groove 8, and the plane where the upper arc is located is parallel to the bottom surface. The bottom angle of the arc side is 45°; the cylindrical specimen placement platform 2 is connected via steps 19 and 20 on the angle adjustment base 4 and bolt fasteners 21; a magnet 16 is placed at the center of the fixed base 5 and connected via wedge-shaped bolt fasteners 17, and the angle adjustment base 4 is connected to the magnetic force it receives via steps 18 on the fixed base 5; the manual adjustment ring 3 and the cylindrical specimen placement platform 2 are threadedly connected, and a reverse groove 15 is provided at the bottom of the manual adjustment ring 3, in which a circular ring piece 14 is stuck, and the symmetrical claw 1 and the circular ring piece 14 are fixedly connected by a spring 13; a long pin 12 is placed in the middle of the spring, and the pin length is consistent with the length of the spring in the relaxed state;

[0040] When the symmetrical clamping jaws 1 are in a clamping state, the height of the symmetrical clamping jaws 1 above the cylindrical sample placement platform 2 is 0.5 mm to 1.5 mm.

[0041] The fixed base 5 and the angle adjustment base 4 are made of martensitic stainless steel, which is a ferromagnetic material. The symmetrical claws 1, the cylindrical sample placement platform 2, and the manual adjustment ring 3 are made of austenitic stainless steel.

[0042] The surface of the cylindrical sample placement platform 2 is respectively marked with marking lines 6 for centering circular samples and marking lines 7 for centering square samples, as well as vertical cross marks 22 for unifying the sample coordinate system and the test system coordinate system.

[0043] The surface of the hand-adjusting ring 3 is processed with anti-slip threads; the angle adjustment base 4 is provided with angle engraved lines 9 with an interval of 1° from 0° to 360°; the fixed base 5 is provided with four evenly distributed fixing bolt holes 11, and a 0° angle marking line 10 is engraved along the diameter direction of the base.

[0044] A testing method for a metal matrix composite fiber ejection test device comprises the following steps:

[0045] 1) Prepare a sample with two parallel end faces and end faces perpendicular to the fiber length direction, with a thickness of 0.1 mm to 0.7 mm;

[0046] 2) Select the high-load module of the nanoindenter and install a conical flat indenter; the conical flat indenter has a flat diameter of 50 μm; the load of the high-load module is 100 mN to 30 N.

[0047] 3) Perform air pressure calibration of the indentation shaft; air pressure calibration of the indentation shaft should be performed before each test after replacing the specimen.

[0048] 4) Calibrate the relative position of the needle tip and the optical microscope: Install the aluminum standard sample on the nanoindenter test platform, make a single indentation or a group of indentations on the aluminum standard sample, and then find the indentation under the nanoindenter optical microscope. Check whether the center of the X-axis and Y-axis cross-marking lines at the center of the optical microscope field of view coincide with the set indentation position. If there is any deviation, adjust them until they are completely aligned.

[0049] 5) Place the sample on the sample placement platform. For regularly shaped samples, use the centering mark to align the sample's X and Y axes with the coordinate system of the test device platform. Place the area where the fibers to be ejected are located above the circular groove 8. Rotate the manual adjustment ring 3 clockwise to move the two jaws 1 downward, clamping the sample edge and securing the sample to be tested.

[0050] 6) Fix the test device fixed base 5 on the nanoindenter test platform by adsorption or bolts;

[0051] 7) In the optical microscope observation interface of the nanoindenter, focus the sample surface, set the working area boundary, and set the test range for the ejection test according to the position of the clamping jaws, that is, the working area of ​​the nanoindenter;

[0052] 8) In the optical microscope observation interface, observe the overall morphology of the sample in the working area, select the fiber to be tested for ejection, and adjust the X and Y axes of the nanoindenter test platform and the rotation angle of the angle adjustment base to make the center of the target fiber cross section coincide with the center of the X and Y axis intersection mark line at the center of the nanoindenter optical microscope field of view;

[0053] 9) In the indentation module of the nanoindenter, select the displacement control mode and the trapezoidal loading function. The loading curve includes: linear loading section - load holding section - linear unloading section. Set the maximum displacement, loading time, load holding time, and unloading time. Start the test. You can set multiple fiber ejection positions at the same time and record the coordinates.

[0054] 10) After the test, starting from the first set position, use the analysis module of the nanoindenter software to obtain the force-displacement curve, and use the in-situ imaging function of the nanoindenter to obtain information such as the length of the ejected fiber and the deformation of the matrix near the fiber;

[0055] 11) Rotate the manual adjustment ring 3 counterclockwise to move the two claws 1 upwards, remove the sample from the cylindrical sample placement platform 2 with tweezers, and place it into the sample box.

[0056] The sample is a fiber-reinforced metal matrix composite material, and the sample is a circular, oval, square, rectangular or irregular sheet-like form. The test plane is a cross-section of the composite sample perpendicular to the fiber length direction. The sample thickness is 0.1mm to 0.5mm, and the fiber diameter is 50μm to 150μm.

[0057] Example 1

[0058] like Figures 1 to 3 As shown, a metal matrix composite fiber ejection test device for nanoindentation includes: symmetrical clamping jaws 1, a cylindrical sample placement platform 2, a manual adjustment ring 3, an angle adjustment base 4 and a fixed base 5, wherein:

[0059] The cylindrical sample placement platform 2 has a circular groove 8 at its center, and the edge of the clamping claw 1 is flush with the edge of the circular groove 8. A marking line 6 for centering circular samples and a marking line 7 for centering square samples are drawn, respectively, as well as a vertical cross-mark 22 for unifying the sample coordinate system and the test system coordinate system. The metal matrix composite material sample to be tested is placed above the circular groove on the platform surface. The hand-adjusting ring 3 is rotated clockwise, and the groove 15 drives the circular ring 14 downward, tightening the spring 13 and applying a vertical downward force to the clamping claw 1, clamping the sample edge and thus fixing the sample. The cylindrical sample placement platform 2 and the angle adjustment base 4 are connected by bolts 21 and steps 19 and 20. The angle adjustment base 4 and the fixed base 5 are both made of ferromagnetic materials and are connected by steps 18 and the magnetic force they are subjected to. Rotating the angle adjustment base 4 drives the sample placement platform 2 to rotate, driving the rotation of the sample, and unifying the X and Y axes of the sample coordinate system with the X and Y axis cross-marks on the nanoindentation test system screen. When removing the sample, rotate the hand-adjusting ring 3 counterclockwise, and the reverse groove 15 drives the annular piece 14 to move upward. When the annular piece contacts the pin 12, continue to rotate the hand-adjusting ring, and the claw is lifted by the pin to remove the sample.

[0060] As a preferred embodiment, the test sample is a fiber-reinforced metal matrix composite material, the sample thickness is 0.1 mm to 0.7 mm, and the fiber diameter is 50 μm to 150 μm.

[0061] As a preferred embodiment, the circular groove 8 is located in the center of the cylindrical sample placement platform 2, and the diameter of the groove is 2 mm to 5 mm.

[0062] As a preferred embodiment, in the clamped state, the height of the clamping claw 1 protruding from the cylindrical sample placement platform 2 is 0.5 mm to 1.5 mm.

[0063] As a preferred embodiment, the fixed base 5 and the angle adjustment base 4 are made of martensitic stainless steel, and the symmetrical claws 1, the cylindrical sample placement platform 2, and the manual adjustment ring 3 are made of austenitic stainless steel.

[0064] Example 2

[0065] In this embodiment, SiC f Taking the / Ti composite material as an example, the fiber diameter is about 100μm, the outer sheath is titanium alloy, and the cross section of the sample is a Φ5mm circular section. The fiber ejection test method includes the following steps:

[0066] 1) Prepare SiC with two parallel ends and end faces perpendicular to the fiber length direction and a thickness of about 0.2 mm f / Ti metal matrix composite test specimens.

[0067] 2) Select the high-load module of the nanoindenter and install a flat conical indenter with a flat diameter of 50 μm.

[0068] 3) Turn on the nanoindenter, enter the operation interface, and perform air pressure calibration of the indentation axis (Air Indent).

[0069] 4) Calibrate the relative position of the needle tip and the optical microscope: Install the aluminum standard sample on the nanoindenter test platform, make an indentation on the aluminum standard sample, and then find it under the nanoindenter optical microscope. Check whether the center of the X and Y axis cross-marking lines at the center of the optical microscope field of view coincides with the set indentation position. If there is any deviation, adjust it to completely coincide.

[0070] 5) Place the sample on the sample placement platform with the center of the sample cross section aligning with the center of the circular centering mark. Make sure that approximately 90% of the fiber area is located above the circular groove, and the outer fiber and sheath area overlap the platform. Rotate the hand adjustment ring clockwise to move the two claws downward, clamp the edge of the sample, and fix the sample to be tested.

[0071] 6) Adsorb the fixed base of the test device onto the nanoindenter test platform.

[0072] 7) Focus the sample surface on the nanoindenter's optical microscope observation interface and set the boundaries of the working area. Since the edges of the jaws align with the edges of the groove on the sample placement platform, the circular area corresponding to the two jaws is the test range for the ejection test, i.e., the nanoindenter's working area.

[0073] 8) In the optical microscope observation interface, observe the overall morphology of the sample in the working area, select the fiber that needs to be tested for ejection test, and adjust the X, Y axis and the rotation angle of the angle adjustment base of the nanoindenter test platform to coincide the center of the target fiber cross section with the center of the X, Y axis cross mark line of the center position of the nanoindenter optical microscope field of view, record the coordinate value displayed by the optical microscope position, and then find and set the next fiber position for ejection test. Similarly, complete the setting of the fiber position of all the fibers that need to be tested for ejection test in the tested section.

[0074] 9) In the indentation module of the nanoindenter, select the displacement control mode, the loading function as trapezoidal loading (linear loading-holding-linear unloading), set the maximum displacement to 10000nm, the loading time to 10s, the holding time to 5s, and the unloading time to 10s, and start the test.

[0075] 10) After the test, starting from the first set position, the force-displacement curve is obtained using the analysis module of the nanoindenter software. The in-situ imaging function of the nanoindenter is used to obtain information such as the length of the ejected fiber and the deformation of the matrix near the fiber.

[0076] 11) Rotate the manual adjustment ring counterclockwise to move the two claws upward. Use tweezers to remove the specimen from the cylindrical specimen platform and place it in the specimen box. The specimen can be placed directly into a scanning electron microscope (SEM). Using the recorded coordinates, locate the fiber that has undergone ejection testing to observe the surface morphology and analyze the micro-elemental elements. Additionally, after SEM observation, if additional fiber ejection testing is deemed necessary, record the coordinates and repeat steps 2) through 11) to repeat the test on the same specimen.

[0077] Example 3

[0078] In this embodiment, the composite material test sample is SiC f / Ti composite material, fiber is SiC f / W composite fiber, with local fiber-to-matrix cracks, and hardness distribution testing along the crack propagation direction near the crack includes the following steps:

[0079] 1) Select the standard load module of the nanoindenter and install the Berkovich indenter.

[0080] 2) Turn on the nanoindenter, enter the operation interface, and perform air pressure calibration of the indentation axis (Air Indent).

[0081] 3) Calibrate the relative position of the needle tip and the optical microscope: Install the aluminum standard sample on the nanoindenter test platform, make an indentation on the aluminum standard sample, and then find it under the nanoindenter optical microscope. Check whether the center of the X and Y axis cross-marking lines at the center of the optical microscope field of view coincides with the set indentation position. If there is any deviation, adjust it to completely coincide.

[0082] 4) Place the sample on the sample placement platform, place the cracked area of ​​the sample above the circular groove, overlap the outer fiber and sheath area on the platform, rotate the hand adjustment ring clockwise to move the two claws down, clamp the edge of the sample, and fix the sample to be tested.

[0083] 5) Adsorb the fixed base of the test device onto the nanoindenter test platform.

[0084] 6) Focus the sample surface on the optical microscope observation interface of the nanoindenter and set the working area boundary according to the crack location of the sample to be tested.

[0085] 7) In the optical microscope observation interface, move the crack position to the center of the nanoindenter optical microscope field of view by adjusting the X and Y axes of the nanoindenter test platform. Rotate the angle adjustment base to drive the manual adjustment ring and the sample placement platform to rotate. The angle adjustment base is provided with angle lines from 0° to 360° with an interval of 1°. A 0° angle marking line is engraved along the diameter direction of the fixed base. According to the deflection angle between the crack propagation direction and the X axis, rotate the angle adjustment base in the opposite direction. Through the rotation of the sample placement platform, rotate the crack propagation direction to coincide with the X axis of the nanoindenter test platform.

[0086] 8) In the automated test interface, set a 40×1 dot matrix with a spacing of 5 μm, starting from the intersection of the X and Y axis crosshairs in the optical microscope.

[0087] 9) In the indentation module of the nanoindenter, select the load control mode, the loading function as trapezoidal loading (linear loading-holding-linear unloading), set the maximum load to 5 mN, the loading time to 5 s, the holding time to 2 s, and the unloading time to 5 s, and start the test.

[0088] 10) After the test, the data is batch processed using the analysis module of the nanoindenter software to obtain a set of hardness and reduced modulus values ​​distributed along the crack propagation direction, and the corresponding contact depth curve (force-displacement curve) is obtained.

[0089] 11) Rotate the manual adjustment ring counterclockwise to move the two jaws upward. Use tweezers to remove the specimen from the cylindrical specimen placement platform and place it in the specimen box. The specimen can be directly placed in a scanning electron microscope. Using the recorded coordinates, locate the crack location for testing hardness distribution, observe the microstructure morphology of the crack area, and analyze the element distribution in the micro area.

[0090] The present invention is simple to operate, effectively prevents sample contamination and damage during the testing process, and improves the accuracy and efficiency of fiber ejection tests for metal-based composite materials. Furthermore, the research ideas proposed in this invention can be easily expanded and applied to nanoindenter indentation and scratch testing of sheet-like specimens made of other materials.

[0091] The above description describes some preferred embodiments of the present invention. However, it should be pointed out that for those skilled in the art, several modifications and changes can be made without departing from the principles of the present invention. These modifications and changes should also be regarded as the scope of protection of the present invention.

Claims

1. A metal matrix composite fiber ejection test device for nanoindentation, characterized by: The invention comprises a symmetrical clamping claw (1), a cylindrical sample placing platform (2), a hand-adjusting ring (3), an angle adjustment base (4) and a fixed base (5); a circular groove (8) is provided at the center position of the end face of the cylindrical sample placing platform (2); the symmetrical clamping claw (1) is installed in the through groove symmetrically provided on the cylindrical sample placing platform (2); the clamping end of the symmetrical clamping claw (1) is approximately a trapezoid, the outer side of the clamping end is a rounded rectangle, the inner bottom side is an arc concentric with the circular groove (8), the arc radius is equal to the circular groove (8), the plane where the upper arc is located is parallel to the bottom surface, and the bottom angle of the trapezoidal arc end side is 45°; the cylindrical sample placing platform (2) is connected to the cylindrical sample placing platform (2) through the angle adjustment base (4 ) is connected with the steps b (19), step c (20) and bolt fasteners (21) on the fixed base (5); a magnet (16) is placed at the center of the fixed base (5) and connected by a wedge-shaped bolt fastener (17); the angle adjustment base (4) is connected with the magnetic force received by the step a (18) on the fixed base (5); the manual adjustment ring (3) and the cylindrical sample placement platform (2) are threadedly connected, and the lower part of the manual adjustment ring (3) is provided with a reverse groove (15), and the annular piece (14) is stuck in the groove. The symmetrical claws (1) and the annular piece (14) are fixedly connected by a spring (13); a long pin (12) is placed in the middle of the spring, and the length of the pin is consistent with the length of the spring in the relaxed state.

2. The metal matrix composite fiber ejection test device for nanoindentation according to claim 1, characterized in that: The circular groove (8) is located in the center of the cylindrical sample placement platform (2), and the diameter of the groove is 2 mm to 5 mm.

3. The metal matrix composite fiber ejection test device for nanoindentation according to claim 1, characterized in that: In the clamping state, the height of the symmetrical clamping claws (1) above the cylindrical specimen placement platform (2) is 0.5 mm to 1.5 mm.

4. The metal matrix composite fiber ejection test device for nanoindentation according to claim 1, characterized in that: The fixed base (5) and the angle adjustment base (4) are made of martensitic stainless steel, which is a ferromagnetic material, and the symmetrical claws (1), the cylindrical sample placement platform (2), and the manual adjustment ring (3) are made of austenitic stainless steel.

5. The metal matrix composite fiber ejection test device for nanoindentation according to claim 1, characterized in that: The surface of the cylindrical sample placement platform (2) is respectively marked with an identification line (6) for aligning a sample having a circular cross section and an identification line a (7) for aligning a square sample, as well as a vertical cross mark (22) for unifying the sample coordinate system and the test system coordinate system.

6. The metal matrix composite fiber ejection test device for nanoindentation according to claim 1, characterized in that: The surface of the hand-adjusting ring (3) is processed with anti-slip threads; the angle adjustment base (4) is provided with angle engraved lines (9) ranging from 0° to 360° at intervals of 1°; the fixed base (5) is provided with four evenly distributed fixing bolt holes (11), and a 0° angle marking line b (10) is engraved along the diameter direction of the base.

7. A metal matrix composite fiber ejection test method, characterized in that: The test method uses the metal matrix composite fiber ejection test device for nanoindentation according to any one of claims 1 to 6, comprising the following steps: 1) Prepare a specimen with two parallel end faces and end faces perpendicular to the fiber length direction, with a thickness of 0.1mm~0.7mm; 2) Select the high-load module of the nanoindenter and install the conical flat indenter; 3) Perform air pressure calibration on the indentation axis; 4) Calibrate the relative position of the needle tip and the optical microscope: Install the aluminum standard sample on the nanoindenter test platform, make a single indentation or a group of indentations on the aluminum standard sample, and then find the indentation under the nanoindenter optical microscope. Check whether the center of the X and Y axis cross mark line at the center of the optical microscope field of view coincides with the set indentation position. If there is any deviation, adjust it to completely coincide. 5) Place the sample on the sample placement platform. For samples with regular shapes, use the centering mark line to align the X and Y axes of the sample with the coordinate system of the test device platform; place the area where the fiber to be ejected is located above the circular groove (8), rotate the hand adjustment ring (3) clockwise to move the two symmetrical claws (1) downward, clamp the edge of the sample, and fix the sample to be tested; 6) Fix the test device fixing base (5) on the nanoindenter test platform by adsorption or bolts; 7) In the optical microscope observation interface of the nanoindenter, focus on the sample surface, set the working area boundary, and set the test range for the ejection test according to the position of the jaws, that is, the working area of ​​the nanoindenter; 8) In the optical microscope observation interface, observe the overall morphology of the sample in the working area, select the fiber that needs to be tested for ejection, and adjust the X and Y axes of the nanoindenter test platform and the rotation angle of the angle adjustment base to make the center of the target fiber cross section coincide with the center of the X and Y axis intersection mark line at the center of the nanoindenter optical microscope field of view; 9) In the indentation module of the nanoindenter, select the displacement control mode and the trapezoidal loading function. The loading curve includes: linear loading section - load holding section - linear unloading section. Set the maximum displacement, loading time, load holding time, and unloading time, and start the test. You can set multiple fiber ejection positions at the same time and record the coordinates. 10) After the test, starting from the first set position, use the analysis module of the nanoindenter software to obtain the force-displacement curve. Use the in-situ imaging function of the nanoindenter to obtain information such as the length of the ejected fiber and the deformation of the matrix near the fiber; 11) Rotate the hand-adjusting ring (3) counterclockwise to move the two symmetrical claws (1) upwards, remove the sample from the cylindrical sample placement platform (2) with tweezers, and place it in the sample box.

8. The metal matrix composite fiber ejection test method according to claim 7, characterized in that: The conical flat indenter used in step 2) has a plane diameter of 50 μm; the load of the high-load module is 100 mN to 30 N.

9. The metal matrix composite fiber ejection test method according to claim 7, characterized in that: The air pressure calibration of the indentation axis in step 3) should be performed before each test after the specimen is replaced.

10. The metal matrix composite fiber ejection test method according to claim 7, characterized in that: The sample is a fiber-reinforced metal matrix composite material, and the sample is a circular, oval, square, rectangular or irregular sheet-like form. The test plane is a cross-section of the composite sample perpendicular to the fiber length direction. The sample thickness is 0.1mm~0.5mm, and the fiber diameter is 50μm~150μm.

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