In-situ generated light high-strength high-plasticity silicon carbide / niobium composite material and preparation method thereof

Abstract

The invention discloses an in-situ generated light high-strength high-plasticity silicon carbide / niobium composite material, which is composed of a niobium silicide, a niobium carbide, a ceramic second phase of silicon carbide and a niobium-based matrix, and has the characteristics of a microcosmic orientation structure and a core-shell structure. The preparation method of the composite material comprises the following steps: step 1, powder mixing; 2, oscillating and orienting; 3, performing cold pressing to form a blank; 4, spark plasma sintering; and 5, hot rolling deformation. According to the composite material, niobium silicide, niobium carbide and light silicon carbide with the density remarkably lower than that of a niobium matrix are introduced into the niobium-based matrix to serve as a ceramic second phase, the overall density of the composite material is effectively reduced, light weight is achieved, the reinforcing effect is achieved, and the strength and high-temperature performance of the composite material are remarkably improved; meanwhile, the characteristics of a microcosmic orientation structure and a core-shell structure are introduced, the plasticity and toughness of the composite material are improved, and the light high-strength high-plasticity silicon carbide / niobium composite material is obtained and is suitable for the fields of aerospace, deep space exploration, weaponry, nuclear engineering and the like.

Description

Technical Field

[0001] This invention belongs to the field of high-performance ceramic-metal composite material preparation technology, specifically relating to an in-situ generation of lightweight, high-strength, and high-plasticity silicon carbide / niobium composite material and its preparation method. Background Technology

[0002] With the rapid development of aerospace, nuclear industry, and deep space exploration, the performance requirements for key structural materials are increasing. In these fields, hot-end components of aero-engines and critical components of hypersonic vehicles need to operate stably for extended periods under harsh conditions such as high temperature, high pressure, oxidation, and corrosion, while also considering cost constraints and implementing lightweight designs. Therefore, developing structural materials that are lightweight, high-strength, and highly ductile is a pressing challenge in the field of materials engineering applications.

[0003] Traditional high-temperature alloys exhibit good and stable service performance in high-temperature applications, but their service temperatures are insufficient to meet the performance requirements of ultra-high service temperatures. Compared to high-temperature alloys, refractory metals can better fill this gap. Among them, niobium (Nb) and its alloys possess high melting points, good strength and ductility, and particularly low density (8.57 g / cm³). 3 Niobium alloys have become a highly promising high-temperature structural material. However, alloy-based niobium alloys still suffer from problems such as difficulty in simultaneously improving strength and ductility, insufficient lightweighting, and limited control over microstructure and properties. To address these issues, materials scientists have adopted a composite design strategy, incorporating a ceramic second phase into the niobium matrix to prepare ceramic / niobium composites. This approach retains the strength and ductility of niobium and the niobium alloy matrix itself while introducing a second phase to better meet service requirements, thus becoming an effective way to improve the overall performance of niobium alloys.

[0004] Silicon carbide (SiC), due to its high melting point, high hardness, high strength, low density, and good thermal stability, is widely used as a key structural component in high-temperature applications such as aerospace, and is also an ideal ceramic reinforcing phase for niobium-based composites. In composites, Nb and SiC undergo a chemical reaction at high temperatures, generating in-situ reinforcing phases such as niobium silicides and niobium carbides. This not only improves the strength and melting point of the composite but also transforms the weak mechanical interfacial bond between the two phases into a stronger chemical bond. Simultaneously, some Si dissolves into Nb to form a niobium-based solid solution, which improves the plasticity and toughness of the composite. Furthermore, the in-situ reaction imparts a core-shell structure to the composite, i.e., the compositional difference from the matrix to the reinforcing phase, effectively alleviating interfacial stress concentration and improving interfacial stability. Therefore, the in-situ reaction not only enhances the interfacial bond between the two phases but also contributes to improving the overall mechanical properties of the composite.

[0005] Compared to the single microstructure and property control strategy of alloying design, microstructure design in composite materials can more effectively improve the mechanical properties of composite materials. Among them, the microstructure of the reinforcing phase arranged in a layered form can effectively induce crack propagation along the interface, avoid catastrophic fracture, and help improve the fracture toughness of composite materials.

[0006] Chinese invention patent (application number 202510618775.3) discloses a novel Nb-Si-Ni-Ti ultra-high temperature structural material and its rapid directional solidification preparation method. This invention designs a composition consisting of an Nb4NiSi phase and an Nb solid solution, and uses a laser direct deposition method combined with rapid solidification technology to prepare the novel Nb-Si-Ni-Ti ultra-high temperature structural material. However, this invention lacks microstructure design, the Nb4NiSi phase generated during the preparation process inevitably impairs the material's ductility and toughness, and the additive manufacturing-based preparation process is complex, making large-scale industrial production difficult. Summary of the Invention

[0007] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing an in-situ generated lightweight, high-strength, and high-ductility silicon carbide / niobium composite material. This composite material introduces niobium silicides, niobium carbides, and lightweight silicon carbide with a density significantly lower than that of the niobium matrix as a ceramic second phase into the niobium matrix. This effectively reduces the overall density of the composite material, achieving lightweighting, and also provides reinforcement, significantly improving the strength and high-temperature performance of the composite material. Simultaneously, it introduces microscopic oriented structures and core-shell structure features into the composite material. Through a combination of compositional and structural design, a novel preparation process is developed, simultaneously achieving lightweight, high-strength, and high-ductility comprehensive mechanical properties in the niobium-based composite material. This solves the problems of the inability to simultaneously achieve strength and ductility in niobium alloys and the resulting poor service performance in existing technologies.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: an in-situ generated lightweight, high-strength, and high-plasticity silicon carbide / niobium composite material, characterized in that the composite material is composed of a ceramic second phase including niobium silicide, niobium carbide, and silicon carbide, and a niobium matrix, wherein the volume fraction of the second phase is 5% to 80%, and the remainder is the niobium matrix; the composite material has microscopic oriented structure and core-shell structure characteristics.

[0009] The aforementioned in-situ generated lightweight, high-strength, and high-plasticity silicon carbide / niobium composite material is characterized in that the niobium silicide is selected from Nb3Si, NbSi2, and Nb5Si3, and the niobium carbide is selected from Nb2C and NbC. The aforementioned niobium silicide and niobium carbide are generated by the in-situ reaction of silicon carbide and niobium during sintering. Compared with conventional physical addition of a second phase, the compounds from the in-situ reaction have cleaner interfaces, higher bonding strength, smaller size, and more dispersed distribution, enabling effective load transfer and improving the strength and plasticity of the material.

[0010] The aforementioned in-situ generated lightweight, high-strength, and highly ductile silicon carbide / niobium composite material is characterized in that the niobium-based matrix is ​​selected from niobium-based solid solutions, Nb-W alloys, Nb-Hf alloys, Nb-Ti-Al alloys, and niobium.

[0011] The above-mentioned in-situ generated lightweight, high-strength, and high-plasticity silicon carbide / niobium composite material is characterized in that the second phase in the composite material exhibits a core-shell structure with silicon-poor niobium carbide as the shell and silicon-rich niobium silicide as the core.

[0012] The aforementioned in-situ generated lightweight, high-strength, and highly ductile silicon carbide / niobium composite material is characterized in that the density of the composite material is 4.2 g / cm³. 3 ~8.5g / cm 3 The hardness of the parallel orientation is 4.2 GPa to 10 GPa, and the hardness of the perpendicular orientation is 3.7 GPa to 8 GPa; the compressive strength of the parallel orientation is 1.8 GPa to 6 GPa, and the compressive failure strain of the parallel orientation is 3% to 18%; the compressive strength of the perpendicular orientation is 1.9 GPa to 4 GPa, and the compressive failure strain of the perpendicular orientation is 3% to 24%; the flexural strength of the perpendicular orientation is 0.95 GPa to 2 GPa, and the flexural failure strain is 0.3% to 1.1%. The composite material of this invention exhibits excellent comprehensive mechanical properties, especially due to its micro-oriented structure, which results in anisotropy in mechanical properties. Specifically, it is stronger and harder along the parallel orientation, and more ductile and tougher along the perpendicular orientation. Parallel orientation refers to the orientation of the applied load parallel to the second phase, and perpendicular orientation refers to the orientation of the applied load perpendicular to the second phase.

[0013] Meanwhile, this invention also discloses a method for preparing lightweight, high-strength, and highly ductile silicon carbide / niobium composite materials in situ as described above, characterized in that the method includes the following steps: Step 1, Powder Mixing: After mixing silicon carbide powder and niobium-based powder, the mixture is placed in a three-dimensional mixer to obtain mixed powder; the mixing rate does not exceed 50 rpm and the time does not exceed 10 hours. Step 2, Powder Orientation: The mixed powder obtained in Step 1 is placed into a cold press mold and then placed in a vibrator for vibration; the vibration frequency is 100Hz~500Hz and the time is 1h~3h. Step 3, Cold pressing of powder: The mixed powder after vibration in step 2 is cold pressed into a blank to obtain a composite blank; the cold pressing pressure is not less than 500MPa and the holding time is 1h; Step 4: Sintering and Shaping: The composite blank obtained in Step 3 is subjected to spark plasma sintering to obtain a composite sintered blank; the heating rate of the spark plasma sintering is 100℃ / min~500℃ / min, the temperature is 1300℃~1700℃, the holding time is 5min~30min, the sintering pressure is 50MPa~100MPa, the sintering atmosphere is vacuum, and the vacuum degree is less than 10. -1 Pa; Step 5, Rolling Deformation: The composite sintered billet obtained in Step 4 is subjected to hot rolling deformation to obtain an in-situ generated lightweight, high-strength, and high-plasticity silicon carbide / niobium composite material; the hot rolling deformation temperature is 900℃~1200℃, the rolling deformation amount is 10%~80%, and the rolling direction is perpendicular to the pressure direction of spark plasma sintering.

[0014] In step two of this invention, the orientation of the powder is achieved using an oscillation process. By limiting the frequency and time of the oscillation, the orientation is better ensured, while avoiding whisker breakage due to excessive time or frequency. In step three, limiting the cold pressing pressure and holding time is beneficial for densification of the composite preform. More preferably, the cold pressing pressure is 500 MPa to 2 GPa. In step four, limiting the sintering temperature, holding time, heating rate, sintering pressure, and vacuum degree of the spark plasma sintering process effectively controls the generation of in-situ chemical reaction products during preparation, facilitating the formation of core-shell structure features and promoting densification of the composite material. More preferably, the heating rate is 100℃ / min to 300℃ / min, the sintering temperature is 1400℃ to 1600℃, the holding time is 5 min to 20 min, and the vacuum degree is less than 5 × 10⁻⁶. -2 Pa; In step five, by limiting the temperature and amount of hot rolling deformation, it is beneficial to optimize the directional structure of the composite material and improve the density and mechanical properties of the composite material. More preferably, the hot rolling temperature is 1000℃~1200℃ and the rolling deformation is 10%~50%.

[0015] The above-described method for preparing a lightweight, high-strength, and highly ductile silicon carbide / niobium composite material in situ is characterized in that the silicon carbide powder in step one is silicon carbide whiskers, with a length of 5 μm to 20 μm, a diameter of 50 nm to 500 nm, and an aspect ratio of not less than 40; the niobium-based powder is selected from one or more of niobium, Nb-W alloy, Nb-Hf alloy, and Nb-Ti-Al alloy, and has a particle size of 100 nm to 10 μm. More preferably, the silicon carbide whiskers have a length of 1 μm to 20 μm, a diameter of 100 nm to 200 nm, and an aspect ratio of 100 to 200; more preferably, the niobium-based powder has a particle size of 100 nm to 1 μm. By limiting the sizes of the silicon carbide whiskers and niobium-based powder, it is more conducive to forming a microscopic oriented structure.

[0016] The above-mentioned method for preparing a lightweight, high-strength, and highly ductile silicon carbide / niobium composite material in situ is characterized in that, in step five, stress-relief annealing is performed after hot rolling deformation at a temperature of 900℃~1200℃ under vacuum for a holding time of 1h~3h. More preferably, the annealing temperature is 900℃~1000℃.

[0017] The above-mentioned method for preparing a lightweight, high-strength, and highly ductile silicon carbide / niobium composite material in situ is characterized in that, in step five, the second phase in the composite material is oriented along the pressure direction perpendicular to the discharge plasma sintering.

[0018] Compared with the prior art, the present invention has the following advantages: 1. In the silicon carbide / niobium composite material of the present invention, through the design of composition and content, the niobium matrix (~8.57 g / cm³) is optimized. 3 The material incorporates niobium silicides, niobium carbides, and lightweight silicon carbide (~3.2 g / cm³), which has a significantly lower density than the niobium matrix. 3 The use of ceramic second phases, such as high-strength ceramic phases, effectively reduces the overall density of composite materials and achieves lightweighting. At the same time, these high-strength ceramic phases play a reinforcing role, significantly improving the strength and high-temperature performance of composite materials. By introducing micro-oriented structures and core-shell structure features into composite materials through structural design, stress concentration at the interface is avoided, and the plasticity and toughness of composite materials are improved, thereby endowing composite materials with high strength and high plasticity.

[0019] 2. This invention employs a series of processes including powder mixing, powder orientation, powder cold pressing, sintering, and rolling deformation to generate lightweight, high-strength, and high-plasticity silicon carbide / niobium composite materials in situ. Powder orientation is achieved through oscillation, ensuring a microscopic oriented structure. Combined with spark plasma sintering and controlled process parameters, the in-situ chemical reaction is effectively regulated. On one hand, niobium silicides and niobium carbides are generated, effectively improving the strength and high-temperature performance of the composite material. On the other hand, a core-shell structure is formed with niobium carbide (silicon-poor) as the shell and niobium silicide (silicon-rich) as the core, which reduces stress concentration, avoids stress shielding at the interface, enhances the interfacial bonding between the two phases, and effectively prevents interfacial cracking, resulting in composite materials with excellent comprehensive mechanical properties.

[0020] 3. This invention uses silicon carbide whiskers as raw materials, which is beneficial for forming a micro-oriented structure through oscillation. On the other hand, it is beneficial for the in-situ generation of niobium silicides and niobium carbides through chemical reaction with the niobium matrix during the spark plasma sintering process. The in-situ reaction products are small in size and have high interfacial bonding strength, which can simultaneously improve the strength and plasticity of the composite material. At the same time, silicon carbide has a low density, which can also significantly reduce the density of the composite material and achieve material lightweighting.

[0021] 4. The composite material prepared by this invention has comprehensive mechanical properties of being lightweight, high-strength, and highly ductile. The preparation process is simple, the process is short, and the cost is controllable. It is expected to replace existing structural components used in high-temperature fields and can be widely used in aerospace, deep space exploration, weaponry, and nuclear engineering.

[0022] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0023] Figure 1 This is a scanning electron microscope image of the silicon carbide / niobium composite material prepared in Example 1 of the present invention.

[0024] Figure 2 The image shows the X-ray diffraction pattern of the silicon carbide / niobium composite material prepared in Example 1 of this invention.

[0025] Figure 3 The compression-strain curve of the silicon carbide / niobium composite material prepared in Example 1 of this invention is shown.

[0026] Figure 4 The bending stress-strain curve of the silicon carbide / niobium composite material prepared in Example 1 of the present invention is shown.

[0027] Figure 5 This is a Vickers hardness histogram of the silicon carbide / niobium composite material prepared in Example 1 of the present invention. Detailed Implementation Example 1 In this embodiment, a lightweight, high-strength, and high-plasticity silicon carbide / niobium composite material is generated in situ. It consists of a ceramic second phase including niobium silicide Nb3Si, niobium carbide Nb2C, NbC, silicon carbide, and a niobium matrix. The volume fraction of the second phase is 5%, and the remainder is the niobium matrix. In the composite material, the second phase is arranged along the pressure direction perpendicular to the spark plasma sintering to form a micro-oriented structure. The second phase exhibits a core-shell structure with silicon-poor niobium carbide as the shell and silicon-rich niobium silicide as the core.

[0028] The preparation method of the in-situ generation of lightweight, high-strength, and highly ductile silicon carbide / niobium composite material in this embodiment includes the following steps: Step 1, Powder Mixing: Silicon carbide whiskers with a length of 5μm and a diameter of 50nm (i.e., an aspect ratio of 100) are mixed with niobium powder with a particle size of 100nm at a mass ratio of 1:40 and then placed in a three-dimensional mixer for mixing. No ball milling media are added during the mixing process. The mixing rate is 20rpm and the time is 8h to obtain mixed powder. Step 2, Powder Orientation: Place the mixed powder obtained in Step 1 into a cold press mold with a diameter of 30 mm, and place the whole mixture in a vibrator for vibration. Before vibration, the powder is kept in a loose state. The vibration frequency is 100 Hz and the time is 1 hour. Step 3, Cold pressing of powder: The mixed powder after vibration in step 2 is placed into a cold press for cold pressing into a blank. The cold pressing pressure is 1 GPa and the holding time is 1 h, to obtain a composite blank with a diameter of 30 mm and a height of not less than 10 mm. Step 4: Sintering and Shaping: The composite green body obtained in Step 3 is placed into a graphite mold for spark plasma sintering. The inner dimensions of the graphite mold are consistent with the dimensions of the composite green body. The heating rate is 100℃ / min, the temperature is 1500℃, the holding time is 5min, the sintering pressure is 50MPa, and the sintering atmosphere is vacuum with a vacuum degree of 5×10⁻⁶. -2 Pa, after cooling, is taken out to obtain a composite sintered blank; Step 5, Rolling Deformation: The composite sintered billet obtained in Step 4 is first placed in a heat treatment furnace for heat treatment at a temperature of 900℃ for 1 hour. Then, it is hot rolled and deformed with a deformation amount of 10%. The rolling direction is perpendicular to the pressure direction of the spark plasma sintering. After each single pass of rolling, it is immediately placed in the heat treatment furnace for heat treatment for 10 minutes before the next pass of rolling is performed. The rolling process is repeated for 5 passes. Then, stress-relief annealing is performed at a temperature of 1000℃ in a vacuum atmosphere for 1 hour. Finally, it is cooled to obtain an in-situ lightweight, high-strength, and high-plasticity silicon carbide / niobium composite material.

[0029] Example 2 In this embodiment, a lightweight, high-strength, and high-plasticity silicon carbide / niobium composite material is generated in situ. It consists of a ceramic second phase including niobium silicide Nb5Si3, niobium carbide Nb2C, NbC, silicon carbide, and a niobium matrix. The volume fraction of the second phase is 20%, and the remainder is the niobium matrix. In the composite material, the second phase is arranged along the pressure direction perpendicular to the spark plasma sintering to form a micro-oriented structure. The second phase exhibits a core-shell structure with silicon-poor niobium carbide as the shell and silicon-rich niobium silicide as the core.

[0030] The preparation method of the in-situ generation of lightweight, high-strength, and highly ductile silicon carbide / niobium composite material in this embodiment includes the following steps: Step 1, Powder Mixing: Silicon carbide whiskers with a length of 10μm and a diameter of 100nm (i.e., an aspect ratio of 100) are mixed with niobium powder with a particle size of 1μm at a mass ratio of 1:10 and then placed in a three-dimensional mixer for mixing. No ball milling media are added during the mixing process. The mixing rate is 15rpm and the time is 6h to obtain mixed powder. Step 2, Powder Orientation: Place the mixed powder obtained in Step 1 into a cold press mold with a diameter of 30mm, and place the whole mixture in a vibrator for vibration. Before vibration, the powder is kept in a loose state. The vibration frequency is 200Hz and the time is 3h. Step 3, Cold pressing of powder: The mixed powder after vibration in step 2 is placed into a cold press for cold pressing into a blank. The cold pressing pressure is 1 GPa and the holding time is 1 h, to obtain a composite blank with a diameter of 30 mm and a height of not less than 10 mm. Step 4: Sintering and Shaping: The composite green body obtained in Step 3 is placed into a graphite mold for spark plasma sintering. The inner cavity dimensions of the graphite mold are consistent with the dimensions of the composite green body. The heating rate is 300℃ / min, the temperature is 1650℃, the holding time is 30min, the sintering pressure is 100MPa, and the sintering atmosphere is vacuum with a vacuum degree of 5×10⁻⁶. -2 Pa, after cooling, is taken out to obtain a composite sintered blank; Step 5, Rolling Deformation: The composite sintered billet obtained in Step 4 is first placed in a heat treatment furnace for heat treatment at a temperature of 1100℃ for 1 hour. Then, hot rolling deformation is performed with a rolling deformation amount of 30%. The rolling direction is perpendicular to the pressure direction of spark plasma sintering. After each single-pass rolling, the billet is immediately placed in a heat treatment furnace for heat treatment for 10 minutes before the next rolling pass is performed. The rolling process is repeated for 5 passes. Then, the billet is cooled to obtain an in-situ lightweight, high-strength, and high-plasticity silicon carbide / niobium composite material.

[0031] Example 3 In this embodiment, a lightweight, high-strength, and high-plasticity silicon carbide / niobium composite material is generated in situ. It consists of niobium silicides Nb3Si, NbSi2, and Nb5Si3, niobium carbides Nb2C and NbC, a ceramic second phase of silicon carbide, and an Nb-5W-2Mo-1Zr alloy matrix. The volume fraction of the second phase is 50%, and the remainder is the Nb-5W-2Mo-1Zr alloy matrix. In the composite material, the second phase is arranged along the pressure direction perpendicular to the spark plasma sintering to form a micro-oriented structure. The second phase exhibits a core-shell structure with silicon-poor niobium carbides as the shell and silicon-rich niobium silicides as the core.

[0032] The preparation method of the in-situ generation of lightweight, high-strength, and highly ductile silicon carbide / niobium composite material in this embodiment includes the following steps: Step 1, Powder Mixing: Silicon carbide whiskers with a length of 20μm and a diameter of 500nm (i.e., an aspect ratio of 40) are mixed with Nb-5W-2Mo-1Zr alloy powder with a particle size of 10μm at a mass ratio of 1:2.8 and then placed in a three-dimensional mixer for mixing. No ball milling media are added during the mixing process. The mixing rate is 15rpm and the time is 4h to obtain mixed powder. Step 2, Powder Orientation: Place the mixed powder obtained in Step 1 into a cold press mold with a diameter of 30 mm, and place the whole mixture in a vibrator for vibration. Before vibration, the powder is kept in a loose state. The vibration frequency is 500 Hz and the time is 3 hours. Step 3, Cold pressing of powder: The mixed powder after vibration in step 2 is placed into a cold press for cold pressing into a blank. The cold pressing pressure is 1 GPa and the holding time is 1 h, to obtain a composite blank with a diameter of 30 mm and a height of not less than 10 mm. Step 4: Sintering and Shaping: The composite green body obtained in Step 3 is placed into a graphite mold for spark plasma sintering. The inner dimensions of the graphite mold are consistent with the dimensions of the composite green body. The heating rate is 200℃ / min, the temperature is 1700℃, the holding time is 10min, the sintering pressure is 50MPa, and the sintering atmosphere is vacuum with a vacuum degree of 5×10⁻⁶. -2 Pa, after cooling, is taken out to obtain a composite sintered blank; Step 5, Rolling Deformation: The composite sintered billet obtained in Step 4 is first placed in a heat treatment furnace for heat treatment at a temperature of 1000℃ for 1 hour. Then, hot rolling deformation is performed with a rolling deformation amount of 50%. The rolling direction is perpendicular to the pressure direction of spark plasma sintering. After each single-pass rolling, the billet is immediately placed in a heat treatment furnace for heat treatment for 10 minutes before the next rolling pass is performed. The rolling process is repeated for 5 passes. Then, the billet is cooled to obtain an in-situ generated lightweight, high-strength, and high-plasticity silicon carbide / niobium composite material.

[0033] Example 4 In this embodiment, a lightweight, high-strength, and high-plasticity silicon carbide / niobium composite material is generated in situ. It consists of niobium silicides Nb3Si and Nb5Si3, niobium carbides Nb2C and NbC, a ceramic second phase of silicon carbide, and an Nb-10Hf-1Ti alloy matrix. The volume fraction of the second phase is 80%, and the remainder is the Nb-10Hf-1Ti alloy matrix. In the composite material, the second phase is arranged along the pressure direction perpendicular to the spark plasma sintering to form a micro-oriented structure. The second phase exhibits a core-shell structure with silicon-poor niobium carbide as the shell and silicon-rich niobium silicide as the core.

[0034] The preparation method of the in-situ generation of lightweight, high-strength, and highly ductile silicon carbide / niobium composite material in this embodiment includes the following steps: Step 1, Powder Mixing: Silicon carbide whiskers with a length of 15μm and a diameter of 300nm (i.e., an aspect ratio of 50) are mixed with Nb-10Hf-1Ti alloy powder with a particle size of 500nm at a mass ratio of 1.5:1 and then placed in a three-dimensional mixer for mixing. No ball milling media are added during the mixing process. The mixing rate is 15rpm and the time is 4h to obtain mixed powder. Step 2, Powder Orientation: Place the mixed powder obtained in Step 1 into a cold press mold with a diameter of 30mm, and place the whole mixture in a vibrator for vibration. Before vibration, the powder is kept in a loose state. The vibration frequency is 300Hz and the time is 2h. Step 3, Cold pressing of powder: The mixed powder after vibration in step 2 is placed into a cold press for cold pressing into a blank. The cold pressing pressure is 1 GPa and the holding time is 1 h, to obtain a composite blank with a diameter of 30 mm and a height of not less than 10 mm. Step 4: Sintering and Shaping: The composite green body obtained in Step 3 is placed into a graphite mold for spark plasma sintering. The inner cavity dimensions of the graphite mold are consistent with the dimensions of the composite green body. The heating rate is 500℃ / min, the temperature is 1300℃, the holding time is 30min, the sintering pressure is 100MPa, and the sintering atmosphere is vacuum with a vacuum degree of 5×10⁻⁶. -2 Pa, after cooling, is taken out to obtain a composite sintered blank; Step 5, Rolling Deformation: The composite sintered billet obtained in Step 4 is first placed in a heat treatment furnace for heat treatment at a temperature of 1200℃ for 1 hour. Then, it is hot rolled and deformed with a rolling deformation amount of 80%. The rolling direction is perpendicular to the pressure direction of spark plasma sintering. After each single-pass rolling, it is immediately placed in the heat treatment furnace for heat treatment for 10 minutes before the next rolling pass is performed. The rolling process is repeated for 5 passes. Then, it is cooled to obtain an in-situ generated lightweight, high-strength, and high-plasticity silicon carbide / niobium composite material.

[0035] The microstructure and phase composition of the silicon carbide / niobium composite material prepared in step five of Example 1 of this invention were analyzed using scanning electron microscopy and X-ray diffraction, respectively. The results are as follows: Figure 1 and Figure 2 As shown.

[0036] Figure 1 The images shown are scanning electron micrographs of the silicon carbide / niobium composite material prepared in Example 1 of this invention. In the left image, the gray phase is the second phase, which is mainly composed of niobium silicide and niobium carbide, and the white phase is the niobium-based solid solution. The second phase is oriented along a specific orientation, as shown by the black arrow. The right image shows the core-shell structure of the composite material. In the second phase, the dark gray niobium silicide is the core, and the light gray niobium carbide is the shell.

[0037] Figure 2 The image shows the X-ray diffraction pattern of the silicon carbide / niobium composite material prepared in Example 1 of this invention. Figure 2 It can be seen that niobium silicide (Nb3Si) and niobium carbide (NbC and Nb2C) exist in the composite material, which proves that silicon carbide and niobium underwent an in-situ reaction at high temperature; in addition, some silicon carbide second phase still exists, and Si element is dissolved in the niobium matrix to form niobium-based solid solution (Nbss).

[0038] The density, hardness, compressive properties, and flexural properties of the silicon carbide / niobium composite materials prepared in Examples 1-4 of this invention were tested using an electronic balance combined with Archimedes' displacement method, a Vickers hardness tester, and a universal testing machine. For the hardness and compressive property tests, the loads were applied parallel to and perpendicular to the second phase orientation, respectively; for the flexural property tests, the loads were applied perpendicular to the second phase orientation. The results are shown in Table 1 and... Figures 3-5 As shown.

[0039] Table 1

[0040] From Table 1 and Figures 3-5 It can be seen that the density of the silicon carbide / niobium composite materials prepared in Examples 1-4 of this invention is 4.2 g / cm³. 3 ~8.5g / cm 3 The parallel orientation hardness is 4.2 GPa to 10 GPa, and the perpendicular orientation hardness is 3.7 GPa to 8 GPa; the parallel orientation compressive strength is 1.8 GPa to 6 GPa, and the parallel orientation compressive failure strain is 3% to 18%; the perpendicular orientation compressive strength is 1.9 GPa to 4 GPa, and the perpendicular orientation compressive failure strain is 3% to 24%; the perpendicular orientation flexural strength is 0.95 MPa to 2 GPa, and the flexural failure strain is 0.3% to 1.1%, indicating that the composite material of the present invention has good comprehensive mechanical properties and exhibits anisotropy in mechanical properties.

[0041] Figure 3 The left and right figures show the compression-strain curves of the silicon carbide / niobium composite material prepared in Example 1 of this invention. The left figure shows the applied load parallel to the second phase orientation, and the right figure shows the applied load parallel to the second phase orientation. Figure 4 The bending stress-strain curve of the silicon carbide / niobium composite material prepared in Example 1 of the present invention is shown, wherein the applied load is perpendicular to the orientation of the second phase; Figure 5 This is a Vickers hardness histogram of the silicon carbide / niobium composite material prepared in Example 1 of the present invention, wherein the applied loads are parallel and perpendicular to the orientation of the second phase, respectively.

[0042] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. An in-situ generated lightweight, high-strength, and highly ductile silicon carbide / niobium composite material, characterized in that, The composite material is composed of a ceramic second phase including niobium silicide, niobium carbide, and silicon carbide, and a niobium matrix, wherein the volume fraction of the second phase is 5% to 80%, and the remainder is the niobium matrix; the composite material has microscopic oriented structure and core-shell structure characteristics.

2. The in-situ generated lightweight, high-strength, and highly ductile silicon carbide / niobium composite material according to claim 1, characterized in that, The niobium silicide is selected from Nb3Si, NbSi2 and Nb5Si3, and the niobium carbide is selected from Nb2C and NbC.

3. The in-situ generated lightweight, high-strength, and highly ductile silicon carbide / niobium composite material according to claim 1, characterized in that, The niobium-based matrix is ​​selected from niobium-based solid solutions, Nb-W alloys, Nb-Hf alloys, Nb-Ti-Al alloys, and niobium.

4. The in-situ generated lightweight, high-strength, and highly ductile silicon carbide / niobium composite material according to claim 1, characterized in that, The second phase in the composite material exhibits a core-shell structure with silicon-poor niobium carbides as the shell and silicon-rich niobium silicides as the core.

5. The in-situ generated lightweight, high-strength, and highly ductile silicon carbide / niobium composite material according to claim 1, characterized in that, The density of the composite material is 4.2 g / cm³. 3 ~8.5g / cm 3 The parallel orientation hardness is 4.2 GPa to 10 GPa, and the perpendicular orientation hardness is 3.7 GPa to 8 GPa; the parallel orientation compressive strength is 1.8 GPa to 6 GPa, and the parallel orientation compressive failure strain is 3% to 18%; the perpendicular orientation compressive strength is 1.9 GPa to 4 GPa, and the perpendicular orientation compressive failure strain is 3% to 24%; the perpendicular orientation flexural strength is 0.95 GPa to 2 GPa, and the flexural failure strain is 0.3% to 1.1%.

6. A method for preparing a lightweight, high-strength, and highly ductile silicon carbide / niobium composite material in situ as described in any one of claims 1 to 5, characterized in that, The method includes the following steps: Step 1, Powder Mixing: After mixing silicon carbide powder and niobium-based powder, the mixture is placed in a three-dimensional mixer to obtain mixed powder; the mixing rate does not exceed 50 rpm and the time does not exceed 10 hours. Step 2, Powder Orientation: The mixed powder obtained in Step 1 is placed into a cold press mold and then placed in a vibrator for vibration; the vibration frequency is 100Hz~500Hz and the time is 1h~3h. Step 3, Cold pressing of powder: The mixed powder after vibration in step 2 is cold pressed into a blank to obtain a composite blank; the cold pressing pressure is not less than 500MPa and the holding time is 1h; Step 4: Sintering and Shaping: The composite blank obtained in Step 3 is subjected to spark plasma sintering to obtain a composite sintered blank; the heating rate of the spark plasma sintering is 100℃ / min~500℃ / min, the temperature is 1300℃~1700℃, the holding time is 5min~30min, the sintering pressure is 50MPa~100MPa, the sintering atmosphere is vacuum, and the vacuum degree is less than 10. -1 Pa; Step 5, Rolling Deformation: The composite sintered billet obtained in Step 4 is subjected to hot rolling deformation to obtain an in-situ generated lightweight, high-strength, and high-plasticity silicon carbide / niobium composite material; the hot rolling deformation temperature is 900℃~1200℃, the rolling deformation amount is 10%~80%, and the rolling direction is perpendicular to the pressure direction of spark plasma sintering.

7. The method for preparing a lightweight, high-strength, and highly ductile silicon carbide / niobium composite material in situ according to claim 6, characterized in that, The silicon carbide powder mentioned in step one is silicon carbide whiskers, with a length of 5μm to 20μm, a diameter of 50nm to 500nm, and an aspect ratio of not less than 40; the niobium-based powder is selected from one or more of niobium, Nb-W alloy, Nb-Hf alloy, and Nb-Ti-Al alloy, and has a particle size of 100nm to 10μm.

8. The method for preparing a lightweight, high-strength, and highly ductile silicon carbide / niobium composite material in situ according to claim 6, characterized in that, In step five, stress-relief annealing is performed after hot rolling deformation. The annealing temperature is 900℃~1200℃, the atmosphere is vacuum, and the holding time is 1h~3h.

9. The method for preparing a lightweight, high-strength, and highly ductile silicon carbide / niobium composite material in situ according to claim 6, characterized in that, In step five, the second phase in the composite material is oriented perpendicular to the pressure direction of the spark plasma sintering.

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