An interface optimization method for biomimetic micro / nano layered Nb / Nb5Si3 composite materials

Abstract

The present application belongs to the technical field of metal matrix composites, and particularly relates to an interface optimization method of a biomimetic micro-nano layered Nb / Nb5Si3 composite material. The biomimetic micro-nano layered Nb / Nb5Si3 composite material provided by the present application generates a nanoscale Nb4C3 interface phase in situ at the semi-coherent Nb-Nb5Si3 interface, and forms a low-mismatch transition interface of Nb-Nb4C3-Nb5Si3 close to the coherent relationship, greatly optimizing the compatibility and synergistic performance of the Nb / Nb5Si3 composite material interface. The interface performance is improved, and at the same time, the dislocation energy continuously slides through the Nb-Nb4C3-Nb5Si3 transition interface to form long-range dislocations, further improving the compressive strength and room temperature toughness of the Nb / Nb5Si3 composite material, which can meet the use requirements of new high-performance aircraft engines. At the same time, the optimization method described in the present application is expected to be the best way to break through the strong-toughness inversion bottleneck of the Nb / Nb5Si3 composite material.

Description

Technical Field

[0001] This invention belongs to the field of metal matrix composite technology, specifically relating to an interface optimization method for a biomimetic micro / nano layered Nb / Nb5Si3 composite material. Background Technology

[0002] The performance of fighter jets heavily relies on the high-temperature structural materials used in their engines. Currently, the operating temperatures of traditional nickel-based high-temperature structural materials for aero engines are nearing their limits, failing to meet the design requirements of high thrust-to-weight ratio aero engines. Nb / Nb5Si3 composite materials possess high melting points (2520℃) and low densities (7.16 g / cm³). 3 High operating temperature (approximately 1400℃), excellent high-temperature strength (σ at 1200℃) b With a tensile strength exceeding 370 MPa, long high-temperature creep life (over 500 hours at 1100℃ and 105 MPa tensile stress), and good oxidation resistance, its target operating temperature is 200-300℃ higher than nickel-based superalloys. It is considered a key high-temperature structural material that can replace current nickel-based superalloys in future applications in aero-engines, showing significant application potential. However, like other intermetallic compounds, the homogenized Nb / Nb5Si3 composite exhibits poor toughness and cold / hot working ability at room temperature, hindering its application in high-temperature structural materials. Although the toughness of Nb / Nb5Si3 composites can be increased to 10 MPa·m through in-situ composite preparation methods... 1 / 2 The above are not sufficient to meet the requirements for high-temperature structural materials in aero engines, which is a key factor hindering their application in aero engines.

[0003] The micro- and nano-layered structures in biological structural materials, with typical layer thicknesses at the submicron or even nanoscale, exhibit a uniform arrangement of hard and brittle phases and plastic phases that are parallel and interlaced, thus endowing them with both strong and tough mechanical properties. This overcomes the bottleneck of the strength-toughness inversion present in traditional metal materials and artificial composite material systems, providing excellent inspiration and enlightenment for the design and control of the comprehensive performance of metal structural materials. For example, the invention patent with application number 201711352916.3 discloses a low-density niobium-based composite material, which is obtained by pressure sintering Nb / Nb5Si3 (Nb2C) layered structures with a layer thickness of several millimeters. It has an alternating distribution of Nb / Nb5Si3 (Nb2C) layered microstructure, exhibiting high high-temperature strength and room-temperature fracture toughness. However, its room-temperature toughness is still difficult to meet the requirements of new high-performance aero-engines.

[0004] Inspired by biomimetic micro / nano-layered structures, the inventors of this patent have successfully developed a method for preparing biomimetic micro / nano-layered Nb / Nb5Si3 composite materials, essentially solving the problem of low room-temperature toughness in Nb / Nb5Si3 alloys. Although previous research achieved some breakthroughs, subsequent studies revealed that the fundamental reason limiting the simultaneous improvement of strength and toughness in biomimetic micro / nano-layered Nb / Nb5Si3 composite materials lies in the presence of numerous semi-coherent Nb-Nb5Si3 mismatched interfaces. These mismatched interfaces lead to significant dislocation blockage and localized stress concentration, resulting in premature mechanical instability. In biomimetic micro / nano-layered materials, the intrinsic properties of the constituent components remain unchanged, but the overall mechanical properties are significantly improved. Besides the fine micro / nano-layered structure, the compatibility and synergistic properties of the interfaces play a crucial role. Optimizing the degree of interface mismatch is an effective means to improve interface compatibility and synergistic properties because it enhances interface matching characteristics. Therefore, in order to fully explore the mechanical potential of biomimetic micro / nano layered Nb / Nb5Si3 composite materials, optimizing and controlling the mismatch degree of the Nb-Nb5Si3 interface to improve its interfacial compatibility and synergistic performance is the best approach. Summary of the Invention

[0005] To address the aforementioned problems in existing technologies, the present invention aims to provide an interface optimization method for biomimetic micro / nano layered Nb / Nb5Si3 composite materials. This invention generates a nanoscale Nb4C3 interface phase in situ at the semi-coherent Nb-Nb5Si3 mismatched interface of the Nb / Nb5Si3 composite material, forming a near-coherent Nb-Nb4C3-Nb5Si3 transition interface, thereby endowing the Nb / Nb5Si3 composite material with higher compressive strength and room-temperature toughness.

[0006] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0007] A method for interface optimization of biomimetic micro / nano layered Nb / Nb5Si3 composite materials includes the following steps:

[0008] 1) Add graphene to anhydrous ethanol and ultrasonically disperse for 0.5–10 h to obtain a graphene dispersion;

[0009] 2) After wet ball milling of Nb powder, Nb flakes with a diameter of 10-30 μm and a thickness of 100-900 nm were obtained by screening.

[0010] 3) Add the Nb flakes and Si powder obtained in step 2) into a ball mill jar at an atomic ratio of Nb:Si of 82.5:17.5. Then add the graphene dispersion obtained in step 1) at a volume fraction of 0.25-0.75% of graphene. Then ball mill the mixture. After the process is complete, vacuum dry the product to obtain the composite powder material.

[0011] 4) The composite powder material obtained in step 3) is loaded into a graphite mold, and then subjected to ultrasonic vibration while an electric field and a magnetic field are applied. The process lasts for 30 to 240 minutes to obtain a composite powder material with Nb sheets arranged in parallel.

[0012] 5) The Nb sheets obtained in step 4) are arranged in parallel composite powder material and vacuum discharge plasma sintering is performed to obtain biomimetic micro-nano layered Nb / Nb5Si3 composite material.

[0013] As a preferred embodiment of the above technical solution, in step 1), the volume of anhydrous ethanol is 100-1000 mL / g based on the mass of graphene, the ultrasonic treatment time is 30-240 min, and the ultrasonic power is 800-2500 W.

[0014] As a preferred embodiment of the above technical solution, in step 2), the wet ball milling uses ethanol as a dispersant, the ball-to-material mass ratio is (5-20):1, the ball milling speed is 300-500 rpm, the time is 1-3 hours, and it is carried out under argon protection.

[0015] As a preferred embodiment of the above technical solution, in step 3), the particle size of the silicon powder is 100–200 nm. The specific process of ball milling is as follows: the ball-to-material mass ratio is (10–20):1, the ball milling speed is 200–300 rpm, and the ball milling time is 90–150 min. The specific process of vacuum drying is as follows: the vacuum degree is -0.09–-0.1 MPa, the temperature is 80–95 °C, and the drying time is 1–3 h.

[0016] As a preferred embodiment of the above technical solution, in step 4), the power of the ultrasonic vibration is 800-2500W, the applied electric field is 3-50V, and the applied magnetic field is 0.2-0.5T.

[0017] As a preferred embodiment of the above technical solution, in step 5), the specific process of vacuum discharge plasma sintering is as follows: vacuum degree is 8-12 Pa, sintering pressure is 55-65 MPa, sintering temperature is 1425-1500℃, and sintering holding time is 15-30 min.

[0018] Preferably, the sintering temperature is 1450℃, and the sintering holding time is 30 min. Under these conditions, graphene can completely form nanoscale Nb4C3 interface phases in situ.

[0019] In the above technical solution, the present invention first subjectes the graphene-containing composite powder material to ultrasonic vibration while simultaneously applying an electric field and a magnetic field, causing the randomly arranged Nb sheets in the graphite mold to exhibit directional alignment. Then, the composite powder, together with the graphite mold, is subjected to vacuum discharge plasma sintering, which allows the graphene to completely generate nanoscale Nb4C3 interface phases in situ. This transforms the semi-coherent Nb-Nb5Si3 mismatched interface into a near-coherent Nb-Nb4C3-Nb5Si3 transition interface, greatly optimizing the compatibility and synergistic performance of the Nb / Nb5Si3 composite material interface, thereby improving its compressive strength and room temperature toughness.

[0020] In summary, the present invention has the following beneficial effects: 1. The biomimetic micro / nano layered Nb / Nb5Si3 composite material provided by the present invention generates a nanoscale Nb4C3 interface phase in situ at the semi-coherent Nb-Nb5Si3 mismatch interface, and forms a near-coherent Nb-Nb4C3-Nb5Si3 transition interface, which greatly improves the compatibility and synergistic performance of the Nb / Nb5Si3 composite material interface, and enables dislocations to continuously slide through the Nb-Nb4C3-Nb5Si3 transition interface to form long-range dislocations, further improving the compressive strength and room temperature toughness of the Nb / Nb5Si3 composite material.

[0021] 2. The preparation process of this invention is simple and the production cost is low. Moreover, the prepared biomimetic micro / nano layered Nb / Nb5Si3 composite material has a compressive strength of up to 2760 MPa and a room temperature toughness of up to 38.9 MPa·m. 1 / 2 This invention can meet the requirements of new high-performance aero engines, and the optimization method described in this invention is expected to be the best way for Nb / Nb5Si3 composite materials to break through the strength-toughness inversion bottleneck. Attached Figure Description

[0022] Figure 1 The image shows the microstructure of the biomimetic micro / nano layered Nb / Nb5Si3 composite material prepared in Example 1. The inset is a magnified analysis of a portion of the composite material.

[0023] Figure 2 This is a microstructure diagram of the biomimetic micro / nano layered Nb / Nb5Si3 composite material prepared in Example 2;

[0024] Figure 3 This is a microstructure diagram of the biomimetic micro / nano layered Nb / Nb5Si3 composite material prepared in Example 3;

[0025] Figure 4 This is a microstructure diagram of the biomimetic micro / nano layered Nb / Nb5Si3 composite material prepared in Example 4;

[0026] Figure 5This is a microstructure diagram of the biomimetic micro / nano layered Nb / Nb5Si3 composite material prepared in Example 5;

[0027] Figure 6 This is a microstructure diagram of the biomimetic micro / nano layered Nb / Nb5Si3 composite material prepared in Comparative Example 1.

[0028] Figure 7 This is a microstructure diagram of the graphene-reinforced Nb / Nb5Si3 composite material prepared in Comparative Example 3. Detailed Implementation

[0029] The technical solution of the present invention will be further described below with reference to specific embodiments. However, the specific details of the embodiments are only for illustrating the present invention and do not represent all technical methods under the concept of the present invention. Therefore, they should not be construed as limiting the overall technical solution of the present invention.

[0030] Example 1

[0031] A method for interface optimization of biomimetic micro / nano layered Nb / Nb5Si3 composite materials includes the following steps:

[0032] 1) Graphene was added to anhydrous ethanol and ultrasonically dispersed for 6 hours to obtain a graphene dispersion. The volume of anhydrous ethanol was 500 mL / g based on the mass of graphene, the ultrasonic treatment time was 120 min, and the ultrasonic power was 1500 W.

[0033] 2) After wet ball milling of Nb powder, Nb flakes with a diameter of 15-30 μm and an average thickness of about 720 nm were obtained by screening. The wet ball milling was carried out under argon protection, with ethanol as the dispersant, a ball-to-material mass ratio of 15:1, a ball milling speed of 400 rpm, and a time of 2 h.

[0034] 3) The Nb flakes and Si powder (particle size 200 nm) obtained in step 2) are added to a ball mill jar at an atomic ratio of Nb:Si of 82.5:17.5. Then, the graphene dispersion obtained in step 1) is added at a volume fraction of 0.50% of graphene. The mixture is then ball-milled. After the milling is completed, the product is vacuum-dried to obtain a composite powder material. The specific ball milling process is as follows: ball-to-material mass ratio of 15:1, ball milling speed of 250 rpm, and ball milling time of 120 min. The specific vacuum drying process is as follows: vacuum degree of -0.09 MPa, temperature of 90℃, and drying time of 2 h.

[0035] 4) The composite powder material obtained in step 3) is loaded into a graphite mold, and then subjected to ultrasonic vibration while applying voltage and magnetic field for 120 minutes to obtain a composite powder material with Nb sheets arranged in parallel; the ultrasonic vibration power is 1800W, the applied voltage is 5V, and the applied magnetic field is 0.2T.

[0036] 5) The Nb sheets arranged in parallel composite powder material obtained in step 4) are subjected to vacuum discharge plasma sintering to obtain a biomimetic micro-nano layered Nb / Nb5Si3 composite material containing a nanoscale Nb4C3 interface phase; the specific process of vacuum discharge plasma sintering is as follows: vacuum degree is 10 Pa, sintering pressure is 60 MPa, sintering temperature is 1450℃, and sintering holding time is 30 min.

[0037] Figure 1 This is a microstructure image of the biomimetic micro / nano-layered Nb / Nb5Si3 composite material prepared in Example 1. The image shows that a nanoscale Nb4C3 interface phase is generated in situ at the Nb-Nb5Si3 mismatched interface, forming a near-coherent Nb-Nb4C3-Nb5Si3 transition interface. Furthermore, the graphene completely reacts to form the nanoscale Nb4C3 phase. The thinnest part of the lamellar Nb phase is approximately 130 nm, the thickest part is approximately 1.3 μm, and the average interlayer spacing is approximately 400 nm. This biomimetic micro / nano-layered Nb / Nb5Si3 composite material exhibits a compressive strength of 2620 MPa and a room-temperature toughness of 35.6 MPa·m. 1 / 2 Compared with existing literature, the biomimetic micro / nano layered Nb / Nb5Si3 composite material has achieved a significant and simultaneous improvement in compressive strength and room temperature toughness due to the effective optimization of the mismatched interfaces in the composite material, and has broken through the inverse relationship between strength and toughness.

[0038] Example 2

[0039] A method for interface optimization of biomimetic micro / nano layered Nb / Nb5Si3 composite materials includes the following steps:

[0040] 1) Graphene was added to anhydrous ethanol and ultrasonically dispersed for 6 hours to obtain an ethanol dispersion of graphene; the volume of anhydrous ethanol was 500 mL / g based on the mass of graphene, the ultrasonic treatment time was 120 min, and the ultrasonic power was 1500 W.

[0041] 2) After wet ball milling of Nb powder, Nb flakes with a diameter of 10-15 μm and an average thickness of about 600 nm were obtained by screening. The wet ball milling was carried out under argon protection, with ethanol as the dispersant, a ball-to-material mass ratio of 10:1, a ball milling speed of 400 rpm, and a time of 2 h.

[0042] 3) The Nb flakes and Si powder (particle size 200 nm) obtained in step 2) are added to a ball mill jar at an atomic ratio of Nb:Si of 82.5:17.5. Then, the graphene dispersion obtained in step 1) is added at a volume fraction of 0.50% of graphene. The mixture is then ball-milled. After the milling is completed, the product is vacuum-dried to obtain a composite powder material. The specific ball milling process is as follows: ball-to-material mass ratio of 15:1, ball milling speed of 250 rpm, and ball milling time of 120 min. The specific vacuum drying process is as follows: vacuum degree of -0.09 MPa, temperature of 90℃, and drying time of 2 h.

[0043] 4) The composite powder material obtained in step 3) is loaded into a graphite mold, and then subjected to ultrasonic vibration while applying voltage and magnetic field for 120 minutes to obtain a composite powder material with Nb sheets arranged in parallel; the ultrasonic vibration power is 1800W, the applied voltage is 5V, and the applied magnetic field is 0.2T.

[0044] 5) The Nb sheets arranged in parallel composite powder material obtained in step 4) are subjected to vacuum discharge plasma sintering to obtain a biomimetic micro-nano layered Nb / Nb5Si3 composite material containing a nanoscale Nb4C3 interface phase; the specific process of vacuum discharge plasma sintering is as follows: vacuum degree is 10 Pa, sintering pressure is 60 MPa, sintering temperature is 1450℃, and sintering holding time is 30 min.

[0045] Figure 2 This is a microstructure image of the biomimetic micro / nano-layered Nb / Nb5Si3 composite material prepared in Example 2. The image shows that the thinnest part of the lamellar Nb phase in this composite material is approximately 35 nm, the thickest part is approximately 1.0 μm, and the average interlayer spacing is 300 nm. Compared with Example 1, the raw material Nb sheets used in this example have a smaller diameter and thinner thickness, resulting in a smaller Nb phase layer thickness and spacing in the composite material. The compressive strength and room temperature toughness of this biomimetic micro / nano-layered Nb / Nb5Si3 composite material are as high as 2760 MPa and 38.9 MPa·m, respectively. 1 / 2 This indicates that the optimization method described in this invention can significantly improve the compressive strength and room temperature toughness of biomimetic micro / nano layered Nb / Nb5Si3 composite materials with different morphological microstructures.

[0046] Example 3

[0047] The interface optimization method in this embodiment is basically the same as that in embodiment 2, except that the process parameters in step 5) are different. Specifically:

[0048] 5) The Nb flakes obtained in step 4) are arranged in parallel and then subjected to vacuum discharge plasma sintering to obtain an Nb / Nb5Si3 composite material containing a nanoscale Nb4C3 interface phase. The specific process of vacuum discharge plasma sintering is as follows: vacuum degree is 10 Pa, sintering pressure is 60 MPa, sintering temperature is 1425℃, and sintering holding time is 30 min.

[0049] Figure 3 This is a microstructure image of the biomimetic micro / nano-layered Nb / Nb5Si3 composite material prepared in Example 3. The image shows the presence of a small number of pores, indicating a decrease in density compared to Examples 1 and 2. Its compressive strength and room temperature toughness are also reduced. This is because the sintering temperature is similar to the melting point of Si, making it difficult to completely densify the composite material. The Nb / Nb5Si3 composite material prepared in this example has a compressive strength of 1986 MPa and a room temperature toughness of 28.6 MPa·m. 1 / 2 .

[0050] Example 4

[0051] The interface optimization method in this embodiment is basically the same as that in embodiment 2, except that the process parameters in step 5) are different. Specifically:

[0052] 5) The Nb flakes obtained in step 4) are arranged in parallel and then subjected to vacuum discharge plasma sintering to obtain an Nb / Nb5Si3 composite material containing a nanoscale Nb4C3 interface phase. The specific process of vacuum discharge plasma sintering is as follows: vacuum degree is 10 Pa, sintering pressure is 60 MPa, sintering temperature is 1450℃, and sintering holding time is 20 min.

[0053] Figure 4 This is a microstructure image of the biomimetic micro / nano-layered Nb / Nb5Si3 composite material prepared in Example 4. Compared with Example 2, the sintering holding time in this example was shorter, resulting in some graphene not reacting to form the Nb4C3 phase. The optimization of the Nb-Nb5Si3 mismatch interface was lower than in Example 2, leading to a decrease in its compressive strength and room temperature toughness. The compressive strength of this Nb / Nb5Si3 composite material is 2198 MPa, and its room temperature toughness is 33.1 MPa·m. 1 / 2 .

[0054] Example 5

[0055] The interface optimization method in this embodiment is basically the same as that in embodiment 2, except that the process parameters in step 5) are different. Specifically:

[0056] 5) The Nb flakes obtained in step 4) are arranged in parallel and then subjected to vacuum discharge plasma sintering to obtain an Nb / Nb5Si3 composite material containing a nanoscale Nb4C3 interface phase. The specific process of vacuum discharge plasma sintering is as follows: vacuum degree is 10 Pa, sintering pressure is 60 MPa, sintering temperature is 1500℃ and sintering holding time is 15 min.

[0057] Figure 5 This is a microstructure image of the biomimetic micro / nano-layered Nb / Nb5Si3 composite material prepared in Example 5. The image shows a significant coarsening of the Nb phase compared to Examples 2, 3, and 4, likely due to the higher preparation temperature. Furthermore, insufficient sintering time resulted in most of the graphene failing to react and form the Nb4C3 phase, leading to a lower degree of optimization of the Nb-Nb5Si3 mismatch interface compared to Examples 2, 3, and 4, further reducing its compressive strength and room-temperature toughness. The Nb / Nb5Si3 composite material exhibits a compressive strength of 2018 MPa and a room-temperature toughness of 31.4 MPa·m. 1 / 2 .

[0058] The above examples show that the density of the biomimetic micro / nano-layered Nb / Nb5Si3 composite material decreases when the sintering temperature is 1425℃, while the Nb phase of the biomimetic micro / nano-layered Nb / Nb5Si3 composite material coarsens when the sintering temperature is 1500℃. Therefore, 1450℃ is the preferred sintering temperature for the biomimetic micro / nano-layered Nb / Nb5Si3 composite material. By controlling the sintering holding time, different nanoscale Nb4C3 interface phase contents can be obtained, thereby regulating the optimization degree of the Nb-Nb5Si3 mismatch interface. Regulating the optimization degree of the Nb-Nb5Si3 mismatch interface can effectively control the room temperature strength and toughness of the biomimetic micro / nano-layered Nb / Nb5Si3 composite material.

[0059] Comparative Example 1

[0060] A method for preparing a biomimetic micro / nano layered Nb / Nb5Si3 composite material includes the following steps:

[0061] 1) After wet ball milling of Nb powder, Nb flakes with a diameter of 15-30 μm and an average thickness of about 720 nm were obtained by screening. The wet ball milling was carried out under argon protection, with ethanol as the dispersant, a ball-to-material mass ratio of 10:1, a ball milling speed of 400 rpm, and a time of 2 h.

[0062] 2) The Nb flakes and Si powder (particle size 200 nm) obtained in step 1) are added to a ball mill jar and ball-milled at an atomic ratio of Nb:Si of 82.5:17.5. After the milling is completed, the product is vacuum-dried to obtain a composite powder material. The specific process of ball milling is as follows: ball-to-material mass ratio of 15:1, ball milling speed of 250 rpm, and ball milling time of 120 min. The specific process of vacuum drying is as follows: vacuum degree of -0.09 MPa, temperature of 90℃, and drying time of 2 h.

[0063] 3) The composite powder material obtained in step 2) is loaded into a graphite mold, and then subjected to ultrasonic vibration while applying voltage and magnetic field for 120 minutes to obtain a composite powder material with Nb sheets arranged in parallel; the ultrasonic vibration power is 1800W, the applied voltage is 5V, and the applied magnetic field is 0.2T.

[0064] 4) The Nb sheets arranged in parallel composite powder material obtained in step 3) are subjected to vacuum discharge plasma sintering to obtain a biomimetic micro-nano layered Nb / Nb5Si3 composite material; the specific process of vacuum discharge plasma sintering is as follows: vacuum degree is 10 Pa, sintering pressure is 60 MPa, sintering temperature is 1450℃, and sintering holding time is 30 min.

[0065] Figure 6 This is a microstructure image of the biomimetic micro / nano-layered Nb / Nb5Si3 composite material prepared in Comparative Example 1. As can be seen from the image, the Nb / Nb5Si3 composite material exhibits a parallel and interlaced arrangement of lamellar Nb phases. The thinnest part of these lamellar Nb phases is approximately 150 nm, the thickest part is approximately 1.3 μm, and the average interlayer spacing is approximately 400 nm. This biomimetic micro / nano-layered Nb / Nb5Si3 composite material achieves a strength of 2314 MPa and a room-temperature fracture toughness of 30.2 MPa·m at room temperature. 1 / 2 Compared with Example 1, the microstructure of Comparative Example 1 is basically the same except that the Nb-Nb5Si3 mismatch interface was not regulated. However, the strength and toughness of the composite material prepared in Example 1 were significantly improved simultaneously compared with Comparative Example 1, indicating that the interface optimization method of this invention can significantly improve the room temperature strength and toughness of the biomimetic micro / nano layered Nb / Nb5Si3 composite material.

[0066] Comparative Example 2

[0067] A method for preparing a biomimetic micro / nano layered Nb / Nb5Si3 composite material includes the following steps:

[0068] 1) After wet ball milling of Nb powder, Nb flakes with a diameter of 10-15 μm and a thickness of about 600 nm were obtained by screening. The wet ball milling was carried out under argon protection, with ethanol as the dispersant, a ball-to-material mass ratio of 10:1, a ball milling speed of 400 rpm, and a time of 2 h.

[0069] 2) The Nb flakes and Si powder (particle size 200 nm) obtained in step 1) are added to a ball mill jar and ball-milled at an atomic ratio of Nb:Si of 82.5:17.5. After the milling is completed, the product is vacuum-dried to obtain a composite powder material. The specific process of ball milling is as follows: ball-to-material mass ratio of 15:1, ball milling speed of 250 rpm, and ball milling time of 120 min. The specific process of vacuum drying is as follows: vacuum degree of -0.09 MPa, temperature of 90℃, and drying time of 2 h.

[0070] 3) The composite powder material obtained in step 2) is loaded into a graphite mold, and then subjected to ultrasonic vibration while applying voltage and magnetic field for 120 minutes to obtain a composite powder material with Nb sheets arranged in parallel; the ultrasonic vibration power is 1800W, the applied voltage is 5V, and the applied magnetic field is 0.2T.

[0071] 4) The Nb sheets arranged in parallel composite powder material obtained in step 3) are subjected to vacuum discharge plasma sintering to obtain a biomimetic micro-nano layered Nb / Nb5Si3 composite material; the specific process of vacuum discharge plasma sintering is as follows: vacuum degree is 10 Pa, sintering pressure is 60 MPa, sintering temperature is 1450℃, and sintering holding time is 30 min.

[0072] This biomimetic micro / nano layered Nb / Nb5Si3 composite material achieves a strength of 2386 MPa and a room-temperature fracture toughness of 34.6 MPa·m at room temperature. 1 / 2 Compared with Example 2, Comparative Example 2 used the same raw materials (Nb flakes and Si powder) and employed the same ball milling and vacuum discharge plasma sintering processes, except that the Nb-Nb5Si3 mismatch interface was not optimized. However, the composite material prepared in Example 2 showed a significant simultaneous improvement in both strength and toughness compared to Comparative Example 2, indicating that the interface optimization method described in this invention can significantly and simultaneously improve the room temperature strength and toughness of the biomimetic micro / nano layered Nb / Nb5Si3 composite material.

[0073] Comparative Example 3

[0074] A method for preparing a graphene-reinforced Nb / Nb5Si3 composite material includes the following steps:

[0075] 1) Graphene was added to anhydrous ethanol and ultrasonically dispersed for 6 hours to obtain an ethanol dispersion of graphene; the volume of anhydrous ethanol was 500 mL / g based on the mass of graphene, the ultrasonic treatment time was 120 min, and the ultrasonic power was 1500 W.

[0076] 2) Nb powder and Si powder (particle size 200nm) were added to a ball mill jar at an atomic ratio of Nb:Si of 82.5:17.5. Then, the graphene dispersion obtained in step 1) was added at a volume fraction of 0.50% of graphene. The mixture was then ball-milled. After the milling was completed, the product was vacuum-dried to obtain a composite powder material. The specific ball milling process was as follows: ball-to-particle mass ratio of 15:1, ball milling speed of 250 rpm, and ball milling time of 120 min. The specific vacuum drying process was as follows: vacuum degree of -0.09 MPa, temperature of 90℃, and drying time of 2 h.

[0077] 3) The composite powder material obtained in step 2) is loaded into a graphite mold and then subjected to vacuum discharge plasma sintering to obtain a Nb / Nb5Si3 composite material containing graphene; the specific process of vacuum discharge plasma sintering is as follows: vacuum degree is 10 Pa, sintering pressure is 60 MPa, sintering holding time is 20 min, and sintering temperature is 1450℃.

[0078] Figure 7 This is a microstructure image of the graphene-reinforced Nb / Nb5Si3 composite material prepared in Comparative Example 3. The image shows that the composite material has a uniform microstructure. The compressive strength of this composite material is 1897 MPa, and its room temperature toughness is 16.7 MPa·m. 1 / 2 Compared with the conventional graphene-reinforced Nb / Nb5Si3 composite material described in Comparative Example 3, Examples 1 and 2 show an increase of approximately 38.1% and 45.5% in room temperature compressive strength, respectively, and an increase of approximately 116.7% and 132.9% in room temperature toughness, respectively. This fully demonstrates the significant creativity and advantages of the interface optimization method described in this invention in improving the room temperature compressive strength and toughness of Nb / Nb5Si3 composite materials.

[0079] This invention breaks away from the traditional approach of using graphene as a reinforcing phase, creatively employing uniformly dispersed graphene as an intermediate medium to generate a nanoscale Nb4C3 interfacial phase through in-situ reaction, which enhances the interfacial compatibility and synergistic properties of Nb / Nb5Si3 composites. The biomimetic micro / nano-layered Nb / Nb5Si3 composite prepared by this invention exhibits significantly higher strength and toughness than both unmodulated biomimetic micro / nano-layered Nb / Nb5Si3 composites and graphene-reinforced Nb / Nb5Si3 composites.

Claims

1. A method for interface optimization of biomimetic micro / nano layered Nb / Nb5Si3 composite materials, characterized in that, Includes the following steps: 1) Add graphene to anhydrous ethanol and ultrasonically disperse for 0.5–10 h to obtain a graphene dispersion; 2) After wet ball milling of Nb powder, Nb flakes with a diameter of 10-30 μm and a thickness of 100-800 nm were obtained by screening. 3) Add the Nb flakes and Si powder obtained in step 2) into a ball mill jar at an atomic ratio of Nb:Si of 82.5:17.

5. Then add the graphene dispersion obtained in step 1) at a volume fraction of 0.25-0.75% of graphene. Then ball mill the mixture. After the process is complete, vacuum dry the product to obtain the composite powder material. 4) The composite powder material obtained in step 3) is loaded into a graphite mold, and then subjected to ultrasonic vibration while an electric field and a magnetic field are applied. The process lasts for 30 to 240 minutes to obtain a composite powder material with Nb sheets arranged in parallel. 5) The Nb sheets obtained in step 4) are arranged in parallel composite powder material and subjected to vacuum discharge plasma sintering to obtain biomimetic micro-nano layered Nb / Nb5Si3 composite material.

2. The interface optimization method for a biomimetic micro / nano layered Nb / Nb5Si3 composite material according to claim 1, characterized in that, In step 1), the volume of anhydrous ethanol is 100-1000 mL / g based on the mass of graphene, the ultrasonic treatment time is 30-240 min, and the ultrasonic power is 800-2500 W.

3. The interface optimization method for a biomimetic micro / nano layered Nb / Nb5Si3 composite material according to claim 1, characterized in that, In step 2), the wet ball milling uses ethanol as a dispersant, the ball-to-material mass ratio is (5-20):1, the ball milling speed is 300-500 rpm, the time is 1-3 hours, and it is carried out under argon protection.

4. The interface optimization method for a biomimetic micro / nano layered Nb / Nb5Si3 composite material according to claim 1, characterized in that, In step 3), the specific process of ball milling is as follows: the ball-to-material mass ratio is (10-20):1, the ball milling speed is 200-300 rpm, and the ball milling time is 90-150 min.

5. The interface optimization method for a biomimetic micro / nano layered Nb / Nb5Si3 composite material according to claim 1, characterized in that, In step 3), the specific process of vacuum drying is as follows: vacuum degree is -0.09 to -0.1 MPa, temperature is 80 to 95°C, and drying time is 1 to 3 hours.

6. The interface optimization method for a biomimetic micro / nano layered Nb / Nb5Si3 composite material according to claim 1, characterized in that, In step 4), the power of the ultrasonic vibration is 800-2500W, the applied electric field is 3-50V, and the applied magnetic field is 0.2-0.5T.

7. The interface optimization method for a biomimetic micro / nano layered Nb / Nb5Si3 composite material according to claim 1, characterized in that, In step 5), the specific process of vacuum discharge plasma sintering is as follows: vacuum degree is 8-12 Pa, sintering pressure is 55-65 MPa, sintering temperature is 1425-1500℃, and sintering holding time is 15-30 min.

8. The interface optimization method for a biomimetic micro / nano layered Nb / Nb5Si3 composite material according to claim 7, characterized in that, In step 5), the sintering temperature of the vacuum discharge plasma sintering is 1450℃, and the sintering holding time is 30min.

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