A si c fiber reinforced metal matrix composite joint sample and a preparation method and application thereof

Abstract

The application relates to the technical field of metal matrix composite structure preparation, in particular to a SiC fiber reinforced metal matrix composite joint sample and a preparation method and application thereof. The structural design of the joint sample comprises an inclined plane joint and a conical surface joint, and the preparation method comprises the following steps: the SiC fiber reinforced metal matrix composite precursor wire and an alloy rod with an inclined plane or a conical surface structure at one end are jointly loaded into a hollow cylindrical alloy sheath, then hot isostatic pressing is adopted, and mechanical processing is carried out, so that the SiC fiber reinforced metal matrix composite joint sample with a specific structural form is obtained. Different forms of metal matrix composite and alloy connection are provided by designing different joint structures. The whole forming of the alloy and the composite material is realized through hot isostatic pressing, the obtained joint can be processed to prepare a tensile sample, the tensile test is carried out, and the research on the mechanical properties and failure behavior of the joint is realized.

Description

Technical Field

[0001] This invention relates to the field of metal matrix composite structural component preparation technology, specifically to a SiC fiber reinforced metal matrix composite joint sample, its preparation method, and its application. Background Technology

[0002] Metal matrix composites prepared by introducing continuous SiC fibers as a reinforcing phase possess low density, high specific strength, high specific stiffness, and excellent high-temperature resistance, creep resistance, and fatigue resistance. They can be applied to lightweight, high-strength structural components in the aerospace industry, such as integral engine blade rings, turbine shafts, connecting rods, piston rods, and skins. However, due to the significant anisotropy of SiC fibers, they exhibit high strength along the fiber direction, while their load-bearing capacity perpendicular to the fiber direction is relatively low. Therefore, in engineering applications, selective reinforcement of metal matrix composite structural components requires rational structural design and demand-driven fiber arrangement. For example, in landing gear structures, fibers can be arranged axially along the cylindrical sandwich layer, or in shaft-type structural components, fibers can be laid at varying angles to improve their torsional resistance.

[0003] In metal matrix composite (MMC) components, the connection between the SiC fiber layup section and the alloy forms the joint region. This region often experiences significant stress concentration during service and may be simultaneously affected by thermal stress, mechanical impact, and chemical environments. MMC applications frequently face technical challenges in joint design and manufacturing, especially under high temperature, high pressure, and complex load conditions, where the stability and mechanical properties of the joint directly impact the overall structural reliability of the component. However, directly evaluating the joint's mechanical properties using actual structural components is not only costly in terms of sample preparation and testing but also time-consuming, hindering systematic optimization of the joint structure and fiber layup scheme. Currently, joint specimens used for mechanical performance testing are mostly plate-shaped. Plate-shaped specimens are prone to deformation or thermal effects during machining (such as milling and wire cutting), while thick plates may warp due to residual stress release. In tensile tests, improper design of the transition zone between the specimen clamping area and the parallel section can easily lead to stress concentration, causing fracture to occur in the non-parallel section, affecting data accuracy and reducing the representativeness of the test results to actual service conditions. Summary of the Invention

[0004] To address the problems existing in the structural design and mechanical property characterization of metal matrix composite joints in current technologies, this invention provides a SiC fiber-reinforced metal matrix composite joint specimen, its preparation method, and its applications. By optimizing the joint interface structure design and combining it with hot isostatic pressing (HIP) technology to achieve integrated molding, the connection reliability and load-bearing capacity of the joint are improved, thus meeting the performance requirements of metal matrix composite joints in aerospace and other fields.

[0005] This invention employs standard rod-shaped specimens. Compared to plate-shaped specimens, standard rod-shaped specimens possess excellent axial symmetry, resulting in a stress state closer to ideal uniaxial tensile conditions during tensile loading. This leads to a more uniform stress distribution, which helps avoid interference from additional bending moments and edge effects on the test results. Therefore, using the joint specimens of this invention to characterize the mechanical properties of joints can significantly reduce testing costs while improving testing efficiency, providing a valid basis for joint structure design and fiber placement schemes. Furthermore, round rod specimens better conform to mechanical property testing standards, resulting in higher repeatability and comparability of test results, making them particularly suitable for characterizing the mechanical properties of joints and interfaces.

[0006] To achieve the above objectives, this invention proposes a method for preparing SiC fiber-reinforced metal matrix composite joint specimens. The method includes the following steps:

[0007] (1) Take the SiC fiber-reinforced metal matrix composite precursor wire, clean it and set it aside;

[0008] (2) Prepare a cylindrical alloy rod, one end of which is a joint and the other end is an end face; the end face of the joint is an inclined plane or a conical surface;

[0009] (3) Prepare a hollow cylindrical alloy cladding, wherein the alloy material of the alloy cladding is the same as that of the alloy rod described in step (2);

[0010] (4) Insert the joint of the alloy rod into one end of the alloy sleeve, and then put two cylindrical alloy plugs on the same side. Fill the other end of the alloy sleeve with multiple pilot wires from step (1) so that the pilot wires abut against the end face of the joint of the alloy rod. After all filling is completed, cut the pilot wires that extend beyond the end face of the alloy sleeve to be flush with the end face of the sleeve. Take out one alloy plug from one side of the alloy rod and put it into the side of the pilot wire. Slowly push it in until both alloy plugs are flush with the end face of the sleeve.

[0011] (5) The alloy plugs are sealed to both ends of the alloy sheath by vacuum electron beam welding to obtain the joint preform;

[0012] (6) After hot isostatic pressing of the joint preform, SiC fiber reinforced metal matrix composite joint samples are obtained.

[0013] The outer diameter of the alloy sheath is 8-15 mm, and the inner diameter is 3-5 mm; the diameter of the alloy rod is 0.01-0.1 mm smaller than the inner diameter of the alloy sheath; the diameter of the SiC fiber-reinforced metal matrix composite precursor wire is 100-160 μm; the diameter of the alloy plug is 0.01-0.1 mm smaller than the inner diameter of the alloy sheath, and it is used for sliding fit.

[0014] Furthermore, the SiC fiber-reinforced metal matrix composite precursor filament described in step (1) is prepared by magnetron sputtering, specifically: using continuous SiC fibers as the substrate and a metal alloy as the target material, with a vacuum degree lower than 4×10⁻⁶. -4 The sputtering parameters are: Pa, target distance 10~150 mm, sputtering power 200~4500 W, sputtering current 1~5 A, deposition rate 0.5~2 μm / h, and gas pressure controlled at 0.5~1.0 Pa during sputtering.

[0015] The metal alloy is one of titanium alloy, aluminum alloy, and high-temperature alloy; the high-temperature alloy is one of nickel-based high-temperature alloy, iron-based high-temperature alloy, and cobalt-based high-temperature alloy.

[0016] In the SiC fiber-reinforced metal matrix composite precursor filament, the volume fraction of SiC fiber is 40-65%.

[0017] The cleaning process involves ultrasonic cleaning with acetone and anhydrous ethanol, with each ultrasonic cleaning session lasting 10–15 minutes. After cleaning, the sample is rinsed with deionized water and then air-dried.

[0018] Further, the alloy rod in step (2) is made of aluminum alloy or titanium alloy; the inclined plane has an angle of 8 to 90°, and the conical surface has an angle of 15 to 180°.

[0019] Furthermore, in step (4), the precursor wires are arranged parallel to each other along the axial direction of the sheath, and adjacent precursor wires are in contact with each other or the gap between them does not exceed 20 μm, so that the precursor wires remain axially parallel and without obvious torsion within the sheath.

[0020] After step (4) is completed, the central cross-section of the joint of the alloy rod is on the central cross-section of the alloy sheath.

[0021] Furthermore, the alloy plug described in step (5) has the same composition as the alloy sheath, and its height is 5~10 mm; the welding parameters are: electron gun vacuum degree ≤9.0×10 -3 Pa; Vacuum chamber vacuum < 4.0 × 10⁻⁶ Pa; -2 Pa; High voltage: 0~85 kV, welding beam current 0~70 mA; Focusing current: 0~700 mA, welding depth ≤3 mm.

[0022] Further, the hot isostatic pressing process parameters in step (6) are: temperature 400~1000 ℃, pressure 80~180MPa, and constant temperature and pressure time 60~240 min.

[0023] The SiC fiber reinforced metal matrix composite joint specimen obtained in step (6) is machined into dumbbell-shaped tensile specimens: during the machining process, the axis of the joint preform after hot isostatic pressing is used as the machining reference for circumferential centering and centering, and the joint interface is centered along the axial direction in the parallel section of the tensile specimen bar.

[0024] The parallel section is a uniform cross-section section used for stress testing in a tensile specimen, and the projection length of the end face of the joint in the horizontal direction does not exceed 1 / 3 of the length of the parallel section.

[0025] A SiC fiber-reinforced metal matrix composite joint sample prepared by the above-described preparation method.

[0026] Application of the above-mentioned SiC fiber-reinforced metal matrix composite joint specimen in the characterization of the mechanical properties of composite joints.

[0027] Advantages and benefits of the present invention

[0028] (1) By designing different joint structures, this invention provides different forms of connection between metal matrix composites and alloys. The joint samples prepared by this method can more conveniently study the mechanical properties of metal matrix composite joint structures.

[0029] (2) The present invention achieves integral molding of alloy and composite material by hot isostatic pressing. The resulting joint can be processed to prepare tensile specimens for tensile testing, so as to realize the study of the mechanical properties and failure behavior of the joint. Attached Figure Description

[0030] Figure 1 This is a flowchart of the method for preparing SiC fiber-reinforced metal matrix composite joint samples according to the present invention; wherein 1 is an alloy rod, 2 is an alloy sheath, and 3 is a pilot wire;

[0031] Figure 2 The drawing shows the fabrication process of the 8° single-bevel joint tensile test bar of SiC fiber-reinforced metal matrix composite material in Example 1.

[0032] Figure 3 This is a schematic diagram of the 8° single-bevel joint tensile specimen bar of SiC fiber-reinforced metal matrix composite material in Example 1;

[0033] Figure 4 This is an industrial CT image of the tensile specimen bar of the SiC fiber-reinforced metal matrix composite material with an 8° single-bevel joint in Example 1.

[0034] Figure 5 The image shows the morphology of the SiC fiber-reinforced metal matrix composite 8° single-bevel joint tensile specimen bar after tensile testing in Example 1.

[0035] Figure 6This is a schematic diagram of the tensile test bar of the SiC fiber-reinforced metal matrix composite material with a 90° tapered joint in Example 2;

[0036] Figure 7 This is an industrial CT image of the tensile specimen bar of the SiC fiber-reinforced metal matrix composite material with a 90° tapered joint in Example 2.

[0037] Figure 8 The image shows the morphology of the SiC fiber-reinforced metal matrix composite 90° tapered joint tensile specimen bar after tensile testing in Example 2.

[0038] Figure 9 The images show the morphology of the SiC fiber-reinforced metal matrix composite tensile specimens with tapered joints at different angles after tensile testing in Example 3.

[0039] Figure 10 This is a schematic diagram of the non-axially centered machining sample of the SiC fiber reinforced metal matrix composite 8° single-bevel joint in Comparative Example 1.

[0040] Figure 11 Industrial CT image of the tensile specimen bar of SiC fiber reinforced metal matrix composite material with an 8° single-bevel joint in Comparative Example 1;

[0041] Figure 12 Industrial CT image of the tensile test bar of SiC fiber reinforced metal matrix composite material with 90° tapered joint eccentric processing in Comparative Example 2. Detailed Implementation

[0042] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0043] Example 1

[0044] A method for preparing an 8° single-bevel joint specimen of SiC fiber reinforced Ti-55531 titanium alloy composite material, the preparation process is as follows: Figure 1 As shown, first, alloy rod 1, alloy sheath 2, and pilot wire 3 are prepared, and then... Figure 1 Assemble the components in the direction indicated by the middle arrow, and obtain the composite material joint sample of this embodiment after hot isostatic pressing. The specific steps include:

[0045] (1) Select a sufficient number of SiC f / Ti-55531 precursor wire (SiC fiber reinforced Ti-55531 titanium matrix composite precursor wire) was ultrasonically cleaned sequentially with acetone and anhydrous ethanol before use. SiC fThe structure of the Ti-55531 precursor wire is as follows: The precursor wire has a SiC fiber core, a length of 60 mm, and is surrounded by a Ti-55531 titanium alloy layer; the SiC fiber has a diameter of 98 μm; SiC... f The Ti-55531 precursor wire has a total diameter of 140 μm and a SiC fiber volume fraction of 49%. This precursor wire was prepared using magnetron sputtering: continuous SiC fibers were used as the substrate, Ti-55531 alloy was used as the target, and the vacuum level was below 4 × 10⁻⁶. -4 Pa was used to deposit a metal alloy layer on the surface of SiC fiber using magnetron sputtering technology. The sputtering target distance was controlled at 150 mm, the sputtering power was 4500 W, the sputtering current was 5 A, the deposition rate was 2 μm / h, and the gas pressure in the coating chamber was controlled at 1.0 Pa during sputtering.

[0046] (2) Select Ti-55531 titanium alloy rods provided by Western Superconducting Technologies as raw materials (the nominal composition of Ti-55531 titanium alloy rods is: Ti-5Al-5Mo-5V-3Cr-1Zr), fix them in the machine tool fixture and perform axis correction; use the axis of the alloy rod as the machining reference to turn the alloy rod to make it into a cylindrical rod with a diameter of Φ3.9±0.02 mm. After machining the cylindrical section, keeping the axis of the alloy rod unchanged, a beveled end with an 8° inclination to the axis is formed at one end of the alloy rod by mechanical cutting. After the bevel is machined, ultrasonic cleaning is performed sequentially with acetone and anhydrous ethanol to remove residual oil, cutting fluid and metal debris from the machining process. Each ultrasonic cleaning takes 10 to 15 minutes. After cleaning, the rod is rinsed with deionized water and dried in a clean environment to obtain a Ti-55531 alloy rod with an 8° bevel at one end. In this embodiment, the total length of the alloy rod is 51.4 mm and the diameter is Φ3.9±0.02 mm.

[0047] (3) Ti-55531 titanium alloy was selected as the raw material and cut to a fixed length of 85 mm. The hollow cylindrical structure was prepared by machining. First, the alloy rod was blanked and the outer diameter was machined to Φ14 mm. Then, the inner hole was formed by drilling and internal finishing. The inner hole size was refined by boring or honing to control the inner diameter within the range of Φ4±0.02 mm. After the inner and outer diameters were machined, the end face was trimmed and deburred. The machined hollow sheath was ultrasonically cleaned with acetone and anhydrous ethanol to remove residual oil, cutting fluid and metal chips. Each ultrasonic cleaning time was 10~15 min. After cleaning, it was rinsed with deionized water and dried in a clean environment to obtain a Ti-55531 hollow sheath with an outer diameter of Φ14 mm, an inner diameter of Φ4±0.02 mm and a length of 85 mm.

[0048] (4) Insert the alloy rod with the bevel (joint part) facing inward into the sheath, and then insert two Ti-55531 alloy plugs on the same side one after the other. Each plug is 5 mm long and has a diameter of Φ3.9±0.02 mm. Then, on the other side of the sheath, insert the SiC obtained in step (1) f The Ti-55531 precursor wires are tightly arranged in the sheath (adjacent precursor wires are in contact with each other or the gap between them does not exceed 20μm), so that the ends of the precursor wires abut against the inclined surface. During operation, the applied force is controlled to avoid bending or breaking of the precursor wires. The portion of the precursor wires that extends beyond the end face of the sheath is trimmed to be flush with the end face of the sheath. Take out a plug from the other side, insert it into one side of the precursor wire, and slowly push it in until the plug is completely inserted into the sheath, until both plugs are flush with the end face of the sheath. At this point, the central cross-section of the alloy rod joint is on the central cross-section of the sheath.

[0049] (5) The plug and the cladding were welded together using vacuum electron beam welding to obtain the pre-formed joint sample. The welding parameters were as follows: electron gun vacuum degree ≤ 9.0 × 10⁻⁶. -3 Pa; Vacuum chamber vacuum < 4.0 × 10⁻⁶ Pa; -2 Pa; High voltage: 85 kV, welding beam current 15 mA; Focusing current: 500 mA, welding depth ≤3 mm.

[0050] (6) The joint sample preform obtained in step (5) is densified by hot isostatic pressing (850℃ / 140MPa / 5h) to obtain SiC. f / Ti-55531 connector round rod blank sample.

[0051] (7) The joint blank sample obtained in step (6) is processed according to the requirements of GB / T 228.1—2010 standard and the corresponding tensile test bar drawings. Figure 2 The tensile specimen bar is prepared by machining. During the machining process, the axis of the joint specimen is used as the machining reference for circumferential centering to avoid geometric eccentricity, ensure that the thickness of the hollow sheath in the specimen bar is uniformly distributed circumferentially after machining, and ensure that the joint interface is axially centered within the parallel section of the tensile specimen bar. Figure 3 As shown.

[0052] Industrial CT scanning was performed on the parallel section of the sample bar processed in this embodiment, and the results are as follows: Figure 4 As shown, the absence of pores at the interface indicates a dense bond between the pilot wire and the alloy. Tensile specimens were prepared using the above method and subjected to tensile tests (GBT 228.1-2010). The tensile specimens that fractured after the test are shown below. Figure 5 As shown, the fracture location of the sample is at the joint interface. This indicates that the joint sample structure and preparation method described in this invention can be used to evaluate SiC. f The tensile properties of the Ti-55531 composite single-bevel joint are required. The tensile strength of this specimen is 1162 MPa.

[0053] Example 2

[0054] A method for preparing a 90° tapered joint specimen of SiC fiber reinforced Ti-55531 titanium alloy composite material. All steps are the same as in Example 1, except for the setting of joint structure and size parameters in step (2) and step (4).

[0055] In this embodiment, step (2) selects Ti-55531 titanium alloy rod as raw material, fixes it in the machine tool fixture and performs axis correction; using the axis of the alloy rod as the machining reference, the alloy rod is turned to form a cylindrical rod with a diameter of Φ3.9±0.02 mm; while keeping the axis of the alloy rod unchanged, a tapered end is formed at one end of the alloy rod by mechanical cutting, and the cone angle of the tapered end is 90° (apex angle); after the tapered end is processed, it is ultrasonically cleaned with acetone and anhydrous ethanol in sequence to remove residual oil, cutting fluid and metal chips during the processing, and the ultrasonic cleaning time is 10 to 15 minutes each time; after cleaning, it is rinsed with deionized water and dried in a clean environment to obtain a tapered Ti-55531 alloy rod with a cone angle of 90° at one end, a cone surface length of 2 mm, a total length of 43.5 mm and a diameter of Φ3.9±0.02 mm.

[0056] In step (4), after the tip of the pilot wire is attached to the bevel of the alloy rod tapered connector, it is ensured that the center cross-section of the alloy rod tapered connector is on the center cross-section of the sheath.

[0057] The processed tensile test bar is as follows Figure 6 As shown, the joint interface is centered in the parallel section.

[0058] Industrial CT scanning was performed on the parallel section of the sample bar processed in this embodiment, and the results are as follows: Figure 7 As shown, the absence of pores at the interface indicates a dense bond between the pilot wire and the alloy. Tensile specimens were prepared using the above method and subjected to tensile tests. The tensile specimens that fractured after the test are shown below. Figure 8 As shown, the joint specimen structure and its preparation method described in this invention can evaluate the tensile properties of SiC fiber-reinforced metal matrix composite tapered joints. The tensile strength of this specimen is 753 MPa.

[0059] Example 3

[0060] In this embodiment, tapered joint samples of SiC fiber reinforced Ti-55531 titanium alloy composite material with different angles were prepared. In step (2), tapered Ti-55531 alloy rods with one end tapering of 16°, 30°, 60° and 120° were prepared respectively. Other steps were the same as in Example 2.

[0061] Tensile specimens were prepared according to the above method and subjected to tensile tests. The tensile specimens that fractured after the test were as follows: Figure 9 As shown, the tensile strengths of the tapered joint specimens with angles of 16°, 30°, 60° and 120° are 766 MPa, 733 MPa, 743 MPa and 682 MPa respectively, and the joints all fracture along the interface.

[0062] Characterization methods in Examples 2 and 3 lead to the conclusion that among the SiC fiber reinforced Ti-55531 titanium alloy composite materials with tapered joints of different angles, the 16° tapered joint exhibits the best tensile properties.

[0063] Comparative Example 1

[0064] In Comparative Example 1, the method for preparing the joint sample was the same as in Example 1, except that:

[0065] In step (4), after the tip of the pilot wire is attached to the bevel of the alloy rod, the center cross-section of the alloy rod bevel joint is not placed on the center cross-section of the sheath, but rather it is placed past the center position and closer to 1 / 3 of the inner end face of the pilot wire side of the sheath, such as... Figure 10 As shown. After processing, the joint interface in the tensile specimen was offset axially and failed to be centrally located within the parallel section of the specimen. The fracture surface of the specimen after the tensile test was located at the alloy section. A CT scan was performed, and the results are as follows. Figure 11As shown, no fracture occurred at the joint interface. The tensile strength of this specimen was 937 MPa, lower than that of the specimen in Example 1. This comparative example illustrates the critical importance of axial centering for the joint specimen; otherwise, it would reduce the accuracy of the mechanical property testing and even lead to premature failure in the non-interface region.

[0066] Comparative Example 2

[0067] In Comparative Example 2, the preparation method of the joint sample was the same as in Example 2, except that:

[0068] In step (7), during the processing of the tensile specimen bar, although the joint interface is controlled to be centered along the axial direction within the parallel section of the specimen bar, the processing reference axis is not guaranteed to be coaxial with the specimen, resulting in the specimen bar being eccentric with the processing axis.

[0069] CT scans were performed on parallel sections of the processed sample, such as... Figure 12 As shown, due to the lack of circumferential centering, the wall thickness of the tensile specimen after processing is unevenly distributed along the circumference, and the center of the alloy end cone is not in the center position. The tensile strength of this specimen is 664 MPa, which is lower than the tensile strength of the specimen in Example 2. The eccentric processing results in a significant reduction in the number of fibers in local areas, which can easily cause uneven stress during subsequent tensile loading, thereby reducing the accuracy of the mechanical property test of the specimen.

[0070] In summary, this invention provides a SiC fiber-reinforced metal matrix composite joint specimen and its preparation method. This method simplifies the joint form in actual components into a specimen structure with a specific geometric configuration. The SiC fiber-reinforced metal matrix composite joint is prepared through structural design and hot isostatic pressing. The core innovation lies in the design of the joint connection form, including single-sloping surfaces and conical structures at different angles. A comparison of the examples and comparative examples shows that the key step is to ensure that the joint specimen's axis is used as the processing reference for centered machining, so that the joint interface is axially centered within the parallel section of the specimen rod, and the thickness of the hollow sheath is uniformly distributed circumferentially, thereby effectively avoiding interference from geometric eccentricity on the mechanical property test results. The joint specimen prepared by this method has advantages such as good structural consistency, high repeatability, and strong reliability of test results. The SiC fiber-reinforced metal matrix composite joint specimen and its preparation method of this invention are suitable for the characterization and engineering application of the mechanical properties of related composite material joints.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a SiC fiber-reinforced metal matrix composite joint specimen, characterized in that, Includes the following steps: (1) Take the SiC fiber-reinforced metal matrix composite precursor wire, clean it and set it aside; (2) Prepare a cylindrical alloy rod, one end of which is a joint and the other end is an end face; the end face of the joint is an inclined plane or a conical surface; (3) Prepare a hollow cylindrical alloy cladding, wherein the alloy material of the alloy cladding is the same as that of the alloy rod described in step (2); (4) Insert the joint of the alloy rod into one end of the alloy sheath, and then place two cylindrical alloy plugs on the same side. Fill the other end of the alloy sheath with multiple pilot wires from step (1) so that the pilot wires abut against the end face of the joint of the alloy rod. After all filling is completed, cut the pilot wires that extend beyond the end face of the alloy sheath to be flush with the end face of the sheath. Take out one alloy plug from one side of the alloy rod and place it on the side of the pilot wires. Slowly push it in until both alloy plugs are flush with the end face of the sheath. At this time, the central cross-section of the joint of the alloy rod is on the central cross-section of the alloy sheath. The pilot wires are arranged parallel to each other along the axial direction of the sheath, and adjacent pilot wires are in contact with each other or their gap does not exceed 20 μm, so that the pilot wires remain axially parallel and without obvious twisting in the sheath. (5) The alloy plugs are sealed to both ends of the alloy sheath by vacuum electron beam welding to obtain the joint preform; (6) After hot isostatic pressing of the joint preform, a SiC fiber reinforced metal matrix composite joint sample is obtained. The outer diameter of the alloy sheath is 8-15 mm, and the inner diameter is 3-5 mm; the diameter of the alloy rod is 0.01-0.1 mm smaller than the inner diameter of the alloy sheath; the diameter of the SiC fiber-reinforced metal matrix composite precursor wire is 100-160 μm; the diameter of the alloy plug is 0.01-0.1 mm smaller than the inner diameter of the alloy sheath, and it is used for sliding fit.

2. The method for preparing SiC fiber-reinforced metal matrix composite joint specimens according to claim 1, characterized in that: The SiC fiber-reinforced metal matrix composite precursor filament described in step (1) is prepared by magnetron sputtering, specifically: using continuous SiC fibers as the substrate and a metal alloy as the target material, with a vacuum degree lower than 4×10⁻⁶. -4 Pa, target distance is 10~150 mm, sputtering power is 200~4500 W, sputtering current is 1~5 A, deposition rate is 0.5~2 μm / h, and gas pressure is controlled at 0.5~1.0 Pa during sputtering; The metal alloy mentioned is one of titanium alloy, aluminum alloy, and high-temperature alloy; In the SiC fiber-reinforced metal matrix composite precursor filament, the volume fraction of SiC fiber is 40-65%. The cleaning process involves ultrasonic cleaning with acetone and anhydrous ethanol, with each ultrasonic cleaning session lasting 10-15 minutes. After cleaning, the sample is rinsed with deionized water and then air-dried.

3. The method for preparing SiC fiber-reinforced metal matrix composite joint specimens according to claim 1, characterized in that: The alloy type of the alloy rod in step (2) is aluminum alloy or titanium alloy; the slope angle of the inclined plane is 8~90°, and the cone angle of the conical surface is 15~180°.

4. The method for preparing SiC fiber-reinforced metal matrix composite joint specimens according to claim 1, characterized in that: The alloy plug described in step (5) has the same composition as the alloy sheath and a height of 5-10 mm; the welding parameters are: electron gun vacuum degree ≤ 9.0 × 10⁻⁶ mm. -3 Pa; Vacuum chamber vacuum < 4.0 × 10⁻⁶ Pa; -2 Pa; high pressure 0~85 kV, welding beam current 0~70mA; focusing current: 0~700 mA, welding depth ≤3 mm.

5. The method for preparing SiC fiber-reinforced metal matrix composite joint specimens according to claim 1, characterized in that: The hot isostatic pressing process parameters in step (6) are: temperature 400~1000 ℃, pressure 80~180 MPa, and constant temperature and pressure time 60~240 min.

6. The method for preparing SiC fiber-reinforced metal matrix composite joint specimens according to claim 1, characterized in that: The SiC fiber reinforced metal matrix composite joint specimen obtained in step (6) is machined into dumbbell-shaped tensile specimens: during the machining process, the axis of the joint preform after hot isostatic pressing is used as the machining reference for circumferential centering and centering, and the joint interface is centered along the axial direction in the parallel section of the tensile specimen bar. The parallel section is a uniform cross-section section used for stress testing in a tensile specimen, and the projection length of the end face of the joint in the horizontal direction does not exceed 1 / 3 of the length of the parallel section.

7. A SiC fiber-reinforced metal matrix composite joint specimen prepared by a method according to any one of claims 1-6.

8. The application of the SiC fiber-reinforced metal matrix composite joint specimen as described in claim 7 in the characterization of the mechanical properties of composite joints.

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