Nano lanthanum hexaboride reinforced titanium-based composite material and preparation method thereof

Abstract

The invention relates to the technical field of metal-based composite materials, in particular to a nanometer lanthanum hexaboride reinforced titanium-based composite material and a preparation method of the nanometer lanthanum hexaboride reinforced titanium-based composite material. The composite reinforcements are uniformly dispersed in the titanium alloy matrix; wherein the composite reinforcement is of a core-shell structure, the core of the core-shell structure is nano lanthanum hexaboride particles, and the shell layer of the core-shell structure is an in-situ reaction layer coating the outer surfaces of the nano lanthanum hexaboride particles; the in-situ reaction layer is a transition layer with components and a structure in gradient change, and the transition layer at least comprises a La / B-rich amorphous transition region and a TiB whisker layer which are distributed from inside to outside. According to the preparation method, low-energy mixing and spark plasma sintering are adopted, controllable in-situ reaction of nano LaB6 and Ti is induced, a LaB6 core and gradient reaction layer core-shell structure composite reinforcement is constructed, and nano La2O3 particles are separated out, so that reinforcement phase agglomeration is inhibited, interface bonding is improved, and the contradiction of strong plasticity inversion is solved.

Description

Technical Field

[0001] This invention relates to the field of metal matrix composites technology, specifically to a nano-lanthanum hexaboride reinforced titanium matrix composite and its preparation method. Background Technology

[0002] Titanium alloys are widely used in aerospace, biomedical, and chemical industries due to their high specific strength, excellent corrosion resistance, and good biocompatibility. However, the insufficient hardness, wear resistance, and high-temperature strength of traditional titanium alloys limit their application in scenarios with higher performance requirements.

[0003] To improve the performance of titanium alloys, researchers often use the method of adding reinforcing phases to prepare titanium-based composites. Among them, discontinuously reinforced titanium-based composites have become a research hotspot due to their isotropic properties and relatively simple preparation process. Commonly used reinforcing phases include ceramic particles such as TiB, TiC, and La2O3. Among them, TiB has been widely studied due to its good lattice matching and compatibility with the titanium matrix. However, single-reinforcing-phase titanium-based composites often face the problem of strength-plasticity inversion, that is, while the strength is increased, the plasticity is significantly reduced. Therefore, the application of rare earth elements and their compounds in titanium-based composites provides a new approach to solving this problem. Lanthanum hexaboride, as a rare earth boride, has advantages such as high melting point, high hardness, low volatility, and excellent chemical stability. In addition, when lanthanum hexaboride reacts with the titanium matrix, it can generate TiB whiskers and La2O3 nanoparticles in situ, forming a multi-scale synergistic reinforcement effect. Lanthanum hexaboride, as a strong deoxidizer, can effectively reduce the oxygen content of alloys and alleviate oxygen embrittlement. The generated La2O3 nanoparticles can pin grain boundaries, hinder dislocation movement, and improve the high-temperature strength and creep resistance of the material. However, this in-situ reaction process is usually difficult to control precisely. The morphology and distribution of the reaction products, as well as the interface structure between the reinforcement and the matrix, are often random, limiting the full realization of its reinforcement potential.

[0004] However, the existing technology for adding nano-lanthanum hexaboride particles to titanium alloy matrices faces two major technical challenges: First, due to their extremely high surface energy, nano-lanthanum hexaboride particles are prone to agglomeration, making it difficult to achieve uniform dispersion in the matrix, forming stress concentration points, and severely impairing the material's plasticity, toughness, and fatigue properties; Second, the poor physical and chemical compatibility between lanthanum hexaboride and the titanium matrix results in weak interfacial bonding, becoming a weak link in the composite material under stress, easily leading to interfacial debonding and crack propagation, causing the material to fail prematurely under actual loads (especially dynamic or high-temperature loads), making it difficult for its strength and reliability to meet theoretical expectations. Summary of the Invention

[0005] This application provides a nano-lanthanum hexaboride reinforced titanium matrix composite material and its preparation method, in order to solve the problems in the prior art where the reinforcing phase is easy to agglomerate and difficult to disperse uniformly, and its weak interfacial bonding with the titanium matrix leads to damage to the plasticity, toughness and other properties of the material, and the strength and reliability cannot meet the theoretical expectations.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The present invention provides a nano-lanthanum hexaboride reinforced titanium-based composite material, such as... Figure 1 As shown, the composite material comprises: a titanium alloy matrix; and a composite reinforcement uniformly dispersed in the titanium alloy matrix; wherein, as Figure 2 As shown, the composite reinforcement has a core-shell structure, wherein the core of the core-shell structure is a nano-lanthanum hexaboride particle, and the shell layer of the core-shell structure is an in-situ reaction layer covering the outer surface of the nano-lanthanum hexaboride particle; the in-situ reaction layer is a transition layer with a gradient change in composition and structure, and the transition layer includes at least a La / B-rich amorphous transition region and a TiB whisker layer distributed from the inside to the outside.

[0007] Furthermore, the composite reinforcement and the titanium alloy matrix are enriched with La2O3 particles at the phase interface, wherein the size of the La2O3 particles is less than 100 nm and they are preferentially distributed at the interface between the TiB whiskers and the titanium alloy matrix.

[0008] Furthermore, the average particle size of the nano-lanthanum hexaboride particles is 50nm-200nm; the average diameter of the TiB whiskers is less than 500nm, and the aspect ratio is greater than 3.

[0009] Furthermore, the content of the nano-lanthanum hexaboride particles is from 0.1 wt.% to 2.0 wt.%; and the content of the TiB whiskers is from 0.5 wt.% to 8.0 wt.%.

[0010] Furthermore, the titanium alloy matrix is ​​a TC4 alloy, a TC11 alloy, or a Ti-Al-Mo-V-Cr β-type titanium alloy.

[0011] This invention also provides a method for preparing nano-lanthanum hexaboride reinforced titanium-based composite materials, characterized by comprising the following steps: S1: Obtain titanium alloy powder and nano-lanthanum hexaboride powder; S2: The titanium alloy powder and nano lanthanum hexaboride powder are mechanically mixed under inert gas protection, wherein the mechanical mixing is performed by low-energy ball milling or three-dimensional mixing machine, so that the nano lanthanum hexaboride powder is uniformly attached to the surface of the titanium alloy powder to obtain composite powder. S3: The composite powder is subjected to spark plasma sintering. By controlling the pulse current parameters and hot pressing parameters of the sintering, the nano-lanthanum hexaboride particles and the titanium alloy matrix are induced to undergo an interfacial reaction, thereby generating the gradient interfacial structure in situ and obtaining a dense composite material blank.

[0012] Furthermore, in step S3, the process parameters for the discharge plasma sintering are: sintering temperature of 900℃-1200℃, sintering pressure of 30MPa-60MPa, and holding time of 5-20 minutes.

[0013] Furthermore, the pulse current is a DC pulse, and the pulse mode is: pulse width of 0.1ms-20ms and pulse interval of 0.1ms-20ms.

[0014] Furthermore, after step S3, step S4 is also included: hot extrusion treatment of the composite material preform, with an extrusion ratio of 8:1 to 15:1 and an extrusion temperature of 900℃-1000℃.

[0015] The present invention also provides a component made of nano-lanthanum hexaboride-reinforced titanium-based composite material through forming.

[0016] The beneficial effects achieved by using the present invention described above are as follows: 1. This invention induces a controllable in-situ reaction between nano-lanthanum hexaboride and surrounding Ti through designed SPS process parameters, actively constructing a composite reinforcement with incompletely reacted nano-lanthanum hexaboride as the core and a gradient reaction layer as the shell. This core-shell structure physically isolates the direct contact between nano-lanthanum hexaboride particles, thereby fundamentally inhibiting their aggregation tendency and ensuring their uniform distribution in the matrix. 2. Simultaneously, the shell generated by the in-situ reaction is not a single phase, but a gradient transition layer with continuously changing composition and structure. This interface structure completely changes the shortcomings of traditional composite materials, such as weak interfacial bonding and easy crack initiation. Among them, the La / B rich amorphous transition region acts as a buffer zone between the nano-lanthanum hexaboride core and the external TiB whiskers. Its amorphous structure can effectively relax and absorb the interfacial stress caused by the mismatch of thermal expansion coefficients, passivate the nucleation and propagation of microcracks, and greatly improve the toughness of the material. The TiB whisker layer has an excellent lattice matching relationship with the titanium matrix, which can form a strong coherent or semi-coherent interfacial bond, realizing the efficient transfer of load from the plastic titanium matrix to the high-strength reinforcement, significantly improving the strength and modulus of the material. The La / B rich amorphous transition region and the TiB whisker layer synergistically solve the contradiction of "strong plasticity inversion" where high strength and high plasticity / toughness are difficult to achieve at the same time. 3. During the sintering process, this invention achieves in-situ precipitation of nanoscale La2O3 particles at the interface between the composite reinforcement and the titanium alloy matrix by precisely controlling the reaction degree. These nanoparticles preferentially pinnate at the interface between the TiB whiskers and the matrix, further refining the matrix grains and strongly hindering dislocation movement, resulting in significant dispersion strengthening and grain refinement effects. Through the synergistic strengthening of multiple scales and mechanisms, including nano-lanthanum hexaboride core support, TiB whisker load transfer, gradient interface stress buffering, and nano-La2O3 interface pinning and dispersion strengthening, a significant improvement in strength, hardness, wear resistance, and creep resistance at both room temperature and high temperature is achieved. 4. The present invention employs a combination of low-energy mixing and spark plasma sintering processes. Low-energy mixing ensures the initial adhesion state of nano-lanthanum hexaboride without introducing excessive defects. Spark plasma sintering, utilizing its high-pulse current-generated localized high temperature, plasma activation, and rapid sintering characteristics, provides the possibility for precise control of the interfacial reaction. By adjusting the pulse current (pulse width, interval) and hot-pressing parameters, the reaction kinetics between nano-lanthanum hexaboride and Ti can be precisely controlled, thereby obtaining the desired gradient interfacial structure rather than a random reaction. Subsequent hot extrusion further eliminates residual porosity, optimizes the microstructure, and makes the material properties more stable and superior. This solves the problems in existing technologies, such as the tendency of the reinforcing phase to agglomerate and be difficult to disperse evenly, and the weak interfacial bonding between the reinforcing phase and the titanium matrix, which leads to damage to the plasticity, toughness and other properties of the material, and the inability to achieve the theoretical expected strength and reliability. Attached Figure Description

[0017] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein...

[0018] Figure 1 This is a schematic diagram of the structure of the composite material provided in the embodiments of the present invention.

[0019] Figure 2 This is a schematic diagram of the structure of the composite reinforcement provided in the embodiments of the present invention.

[0020] Figure 3 This is a scanning electron microscope image of the nano-lanthanum hexaboride-reinforced titanium-based composite material provided in Example 1 of this invention.

[0021] Figure 4 This is a scanning electron microscope image of the nano-lanthanum hexaboride-reinforced titanium-based composite material provided in Example 2 of this invention.

[0022] Figure 5 This is a scanning electron microscope image of the nano-lanthanum hexaboride-reinforced titanium-based composite material provided in Example 3 of this invention.

[0023] Figure 6This is a scanning electron microscope image of the nano-lanthanum hexaboride-reinforced titanium-based composite material provided in Comparative Example 1 of this invention.

[0024] Figure 7 This is a scanning electron microscope image of the nano-lanthanum hexaboride-reinforced titanium-based composite material provided in Comparative Example 2 of this invention.

[0025] Figure 8 This is a scanning electron microscope image of the nano-lanthanum hexaboride-reinforced titanium-based composite material provided in Comparative Example 3 of this invention.

[0026] Figure 9 This is a DSC schematic diagram of the composite material provided in the embodiments of the present invention.

[0027] Figure 10 This is an XPS diagram of the nano-lanthanum hexaboride-reinforced titanium-based composite material provided in the embodiments of the present invention, located at 5 nm.

[0028] Figure 11 This is an XPS diagram of the nano-lanthanum hexaboride-reinforced titanium-based composite material provided in the embodiments of the present invention at a depth of 15 nm.

[0029] Figure 12 This is an XPS diagram of the nano-lanthanum hexaboride-reinforced titanium-based composite material provided in the embodiments of the present invention at a depth of 30 nm.

[0030] Figure 13 This is an XPS diagram of the nano-lanthanum hexaboride-reinforced titanium-based composite material provided in the embodiments of the present invention at a wavelength of 50 nm.

[0031] Figure 14 This is an XPS diagram of the nano-lanthanum hexaboride-reinforced titanium-based composite material provided in the embodiments of the present invention at 80 nm. Detailed Implementation

[0032] The technical solution of the present invention is illustrated below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or defining the scope of the present invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the present invention.

[0033] To better understand the above technical solutions, exemplary embodiments of the present invention are described in more detail below. While exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the invention to those skilled in the art.

[0034] The following description, with reference to the accompanying drawings, illustrates an embodiment of a nano-lanthanum hexaboride-reinforced titanium-based composite material and its preparation method. Addressing the issue of weak interfacial bonding mentioned in the background section, this application provides a nano-lanthanum hexaboride-reinforced titanium-based composite material. This invention addresses the performance shortcomings of existing nano-lanthanum hexaboride-reinforced titanium-based composite materials, which suffer from easy agglomeration of the reinforcing phase and weak interfacial bonding with the titanium matrix. It employs a combination of low-energy mixing and spark plasma sintering (SPS) processes. By precisely controlling the pulse current and hot-pressing parameters, a controllable in-situ reaction between nano-lanthanum hexaboride and the titanium matrix is ​​achieved, constructing a gradient composite material with continuously changing composition and structure, centered on incompletely reacted nano-lanthanum hexaboride. The composite reinforcement, with a reaction layer as the shell, fundamentally isolates particles from direct contact, inhibiting agglomeration to ensure uniform dispersion. The La / B-rich amorphous transition region in the gradient transition layer relaxes interfacial stress and passivates microcracks, while the TiB whisker layer forms a strong interfacial bond with the matrix for efficient load transfer. These two elements synergistically resolve the contradiction between strong plasticity and weak ductility. Simultaneously, nano-La2O3 particles precipitated in situ during sintering achieve dispersion strengthening and grain refinement by pinning grain boundaries and hindering dislocation movement. Subsequent hot extrusion further eliminates residual porosity and optimizes the microstructure. Ultimately, through the synergistic effect of LaB6 core bearing, TiB whisker load transfer, gradient interfacial stress buffering, and nano-La2O3 reinforcement, the composite material's strength, hardness, wear resistance, and creep resistance at room and high temperatures are significantly improved, solving the problems of impaired plasticity and toughness and unmet theoretical strength reliability in existing technologies.

[0035] All raw materials used in the embodiments of this application have clear commercial sources. The titanium alloy powder is TC4 (Ti-6Al-4V) pre-alloyed spherical powder conforming to GB / T3620 standard, with a particle size range of 15-53μm and an oxygen content of ≤0.13%. The nano lanthanum hexaboride powder is purchased from Shanghai Aladdin Biochemical Technology, with a purity of ≥99% and an average particle size of 50-200nm. The spark plasma sintering system is the SPS-625 sintering system manufactured by Fuji Electric Industries, Ltd. of Japan. The high-purity argon gas used for sintering comes from Beijing Praxair Practical Gases Co., Ltd.

[0036] The present invention will be further described in conjunction with the following embodiments.

[0037] Example 1 This invention provides a nano-lanthanum hexaboride reinforced titanium-based composite material, such as... Figure 1 As shown, the composite material includes: a titanium alloy matrix; and a composite reinforcement uniformly dispersed in the titanium alloy matrix; wherein, as... Figure 2 As shown, the composite reinforcement has a core-shell structure, wherein the core of the core-shell structure is a nano-lanthanum hexaboride particle, and the shell of the core-shell structure is an in-situ reaction layer covering the outer surface of the nano-lanthanum hexaboride particle; the in-situ reaction layer is a transition layer with a gradient change in composition and structure, and the transition layer includes at least a La / B rich amorphous transition region and a TiB whisker layer distributed from the inside to the outside.

[0038] Furthermore, La2O3 particles are enriched at the interface between the composite reinforcement and the titanium alloy matrix. The size of the La2O3 particles is less than 100 nm, and they are preferentially distributed at the interface between the TiB whiskers and the titanium alloy matrix.

[0039] Furthermore, the average particle size of the nano-lanthanum hexaboride particles is 50nm-200nm; the average diameter of the TiB whiskers is less than 500nm, and the aspect ratio is greater than 3.

[0040] Furthermore, the content of nano-lanthanum hexaboride particles is 0.1 wt.%; the content of TiB whiskers is 0.5 wt.%.

[0041] Furthermore, the titanium alloy matrix is ​​TC4 alloy.

[0042] This invention also provides a method for preparing nano-lanthanum hexaboride reinforced titanium-based composite materials, characterized by comprising the following steps: S1: Obtain titanium alloy powder and nano-lanthanum hexaboride powder; S2: Under inert gas protection, titanium alloy powder and nano lanthanum hexaboride powder are mechanically mixed, wherein the mechanical mixing is performed by low-energy ball milling or three-dimensional mixer mixing, so that the nano lanthanum hexaboride powder is uniformly attached to the surface of the titanium alloy powder to obtain composite powder. S3: The composite powder is subjected to spark plasma sintering. By controlling the pulse current parameters and hot pressing parameters of sintering, an interfacial reaction is induced between the nano-lanthanum hexaboride particles and the titanium alloy matrix, generating a gradient interfacial structure in situ, and obtaining a dense composite material blank.

[0043] Furthermore, in step S3, the process parameters for spark plasma sintering are: sintering temperature of 900℃, sintering pressure of 30MPa, and holding time of 5 minutes.

[0044] Furthermore, the pulse current is a DC pulse, and the pulse mode is: pulse width of 0.1ms and pulse interval of 0.1ms.

[0045] Furthermore, after step S3, step S4 is also included: hot extrusion treatment of the composite material preform, with an extrusion ratio of 8:1 and an extrusion temperature of 900℃.

[0046] The present invention also provides a component made of nano-lanthanum hexaboride-reinforced titanium-based composite material through forming.

[0047] Example 2 This invention provides a nano-lanthanum hexaboride reinforced titanium-based composite material, such as... Figure 1 As shown, the composite material includes: a titanium alloy matrix; and a composite reinforcement uniformly dispersed in the titanium alloy matrix; wherein, as... Figure 2 As shown, the composite reinforcement has a core-shell structure, wherein the core of the core-shell structure is a nano-lanthanum hexaboride particle, and the shell of the core-shell structure is an in-situ reaction layer covering the outer surface of the nano-lanthanum hexaboride particle; the in-situ reaction layer is a transition layer with a gradient change in composition and structure, and the transition layer includes at least a La / B rich amorphous transition region and a TiB whisker layer distributed from the inside to the outside.

[0048] Furthermore, La2O3 particles are enriched at the phase interface between the composite reinforcement and the titanium alloy matrix, wherein La2O 33 The particle size is less than 100 nm and is preferentially distributed at the interface between TiB whiskers and the titanium alloy matrix.

[0049] Furthermore, the average particle size of the nano-lanthanum hexaboride particles is 50nm-200nm; the average diameter of the TiB whiskers is less than 500nm, and the aspect ratio is greater than 3.

[0050] Furthermore, the content of nano-lanthanum hexaboride particles is 1.0 wt.%; the content of TiB whiskers is 4.0 wt.%.

[0051] Furthermore, the titanium alloy matrix is ​​TC11 alloy.

[0052] This invention also provides a method for preparing nano-lanthanum hexaboride reinforced titanium-based composite materials, characterized by comprising the following steps: S1: Obtain titanium alloy powder and nano-lanthanum hexaboride powder; S2: Under inert gas protection, titanium alloy powder and nano lanthanum hexaboride powder are mechanically mixed, wherein the mechanical mixing is performed by low-energy ball milling or three-dimensional mixer mixing, so that the nano lanthanum hexaboride powder is uniformly attached to the surface of the titanium alloy powder to obtain composite powder. S3: The composite powder is subjected to spark plasma sintering. By controlling the pulse current parameters and hot pressing parameters of sintering, an interfacial reaction is induced between the nano-lanthanum hexaboride particles and the titanium alloy matrix, generating a gradient interfacial structure in situ, and obtaining a dense composite material blank.

[0053] Furthermore, in step S3, the process parameters for spark plasma sintering are: sintering temperature of 1050℃, sintering pressure of 45MPa, and holding time of 15 minutes.

[0054] Furthermore, the pulse current is a DC pulse, and the pulse mode is: pulse width of 10ms and pulse interval of 10ms.

[0055] Furthermore, after step S3, step S4 is also included: hot extrusion treatment of the composite material preform, with an extrusion ratio of 11:1 and an extrusion temperature of 950°C.

[0056] The present invention also provides a component made of nano-lanthanum hexaboride-reinforced titanium-based composite material through forming.

[0057] Example 3 This invention provides a nano-lanthanum hexaboride reinforced titanium-based composite material, such as... Figure 1 As shown, the composite material includes: a titanium alloy matrix; and a composite reinforcement uniformly dispersed in the titanium alloy matrix; wherein, as... Figure 2 As shown, the composite reinforcement has a core-shell structure, wherein the core of the core-shell structure is a nano-lanthanum hexaboride particle, and the shell of the core-shell structure is an in-situ reaction layer covering the outer surface of the nano-lanthanum hexaboride particle; the in-situ reaction layer is a transition layer with a gradient change in composition and structure, and the transition layer includes at least a La / B rich amorphous transition region and a TiB whisker layer distributed from the inside to the outside.

[0058] Furthermore, La2O3 particles are enriched at the interface between the composite reinforcement and the titanium alloy matrix. The size of the La2O3 particles is less than 100 nm, and they are preferentially distributed at the interface between the TiB whiskers and the titanium alloy matrix.

[0059] Furthermore, the average particle size of the nano-lanthanum hexaboride particles is 50nm-200nm; the average diameter of the TiB whiskers is less than 500nm, and the aspect ratio is greater than 3.

[0060] Furthermore, the content of nano-lanthanum hexaboride particles is 2.0 wt.%; and the content of TiB whiskers is 8.0 wt.%.

[0061] Furthermore, the titanium alloy matrix is ​​a Ti-Al-Mo-V-Cr β-type titanium alloy.

[0062] This invention also provides a method for preparing nano-lanthanum hexaboride reinforced titanium-based composite materials, characterized by comprising the following steps: S1: Obtain titanium alloy powder and nano-lanthanum hexaboride powder; S2: Under inert gas protection, titanium alloy powder and nano lanthanum hexaboride powder are mechanically mixed, wherein the mechanical mixing is performed by low-energy ball milling or three-dimensional mixer mixing, so that the nano lanthanum hexaboride powder is uniformly attached to the surface of the titanium alloy powder to obtain composite powder. S3: The composite powder is subjected to spark plasma sintering. By controlling the pulse current parameters and hot pressing parameters of sintering, an interfacial reaction is induced between the nano-lanthanum hexaboride particles and the titanium alloy matrix, generating a gradient interfacial structure in situ, and obtaining a dense composite material blank.

[0063] Furthermore, in step S3, the process parameters for spark plasma sintering are: sintering temperature of 1200℃, sintering pressure of 60MPa, and holding time of 20 minutes.

[0064] Furthermore, the pulse current is a DC pulse, and the pulse mode is: pulse width of 20ms and pulse interval of 20ms.

[0065] Furthermore, after step S3, step S4 is also included: hot extrusion treatment of the composite material blank, with an extrusion ratio of 15:1 and an extrusion temperature of 1000℃.

[0066] The present invention also provides a component made of nano-lanthanum hexaboride-reinforced titanium-based composite material through forming.

[0067] Comparative Example 1 A conventional in-situ self-generated titanium-based composite material, directly mixed with micron-sized TiB2, is presented. The titanium alloy matrix is ​​the same TC11 alloy as in Example 2, and the reinforcing phase is micron-sized titanium diboride powder, with the same addition amount as in Example 2. Preparation method: TC11 alloy powder and micron-sized TiB2 powder are mixed in a three-dimensional mixer for 8 hours under argon protection. Sintering and subsequent hot extrusion are performed using the same SPS process as in Example 2.

[0068] Comparative Example 2 A composite material with directly added nano-LaB6 but without forming a complete gradient shell is identical to that of Example 2, namely a TC11 matrix with a nano-LaB6 addition amount of 1.0 wt.%. The mixing process is the same as in Example 2, using conventional pressureless sintering instead of SPS. Sintering is carried out in a high-temperature vacuum sintering furnace at a sintering temperature of 1100°C and a holding time of 120 minutes to ensure complete sintering, but without applying pressure and without pulsed current activation effect.

[0069] Comparative Example 3 A nano-lanthanum hexaboride-reinforced titanium-based composite material is different from Example 2 only in that it uses high-energy ball milling instead of low-energy mixing; the other components and preparation process are the same as in Example 2.

[0070] Performance testing The materials prepared in Examples 1-3 and Comparative Examples 1-3 of this invention were subjected to systematic mechanical property testing and microstructure characterization, and the results are shown below.

[0071] like Figures 3-5 As shown, in backscattered electron mode, reinforcements with varying brightness and darkness were uniformly distributed within the titanium alloy matrix in Examples 1-3. At high magnification, the reinforcement exhibited a clear core-shell structure, with no visible cracks between the core and shell, or between the shell and the matrix, indicating a tight bond. La was mainly enriched in the core region, B diffused from the core to the outer shell, while Ti permeated from the matrix into the shell, confirming the existence of a transition layer with a gradient in composition and structure.

[0072] like Figure 6 As shown, rod-shaped TiB whiskers are visible in the microstructure of Comparative Example 1, but their interface with the titanium matrix is ​​clear and straight, and no obvious compositional transition layer is observed. Figure 7 As shown, the microstructure of Comparative Example 2 mainly consists of coarse, unevenly distributed TiB whiskers and bulk compounds; no complete, regular core-shell structure was observed. Figure 8 As shown, obvious micron-scale agglomerates can be observed in Comparative Example 3. Energy dispersive spectroscopy analysis confirmed that the agglomerates were LaB6, proving the severe agglomeration of nanoparticles.

[0073] The room temperature tensile test was conducted according to GB / T228.1 standard, and the Vickers hardness test was conducted according to GB / T4340.1 standard. The results are shown in Table 1 below.

[0074] Table 1. Results of room temperature mechanical properties test

[0075] As shown in Table 1, the three embodiments of the present invention are significantly superior to the comparative examples in both strength and hardness, thanks to the strong load-bearing capacity of the core-shell composite reinforcement and the gradient interface. More importantly, while achieving high strength, the embodiments maintain an elongation rate far exceeding that of the comparative examples, successfully solving the problem of "inverted strength-plasticity". This demonstrates the crucial role of the gradient interface structure in coordinating deformation and improving toughness.

[0076] Comparative Example 1, lacking multi-scale synergistic reinforcement and a tough interface, exhibited performance significantly lower than the Example 1. Comparative Example 2, due to structural instability, had the worst performance, demonstrating that precise process control is crucial for obtaining the ideal structure. Comparative Example 3, due to severe agglomeration defects, showed a sharp deterioration in both strength and plasticity, highlighting the importance of low-energy mixing for ensuring initial dispersion.

[0077] Therefore, with the increase of the amount of nano-lanthanum hexaboride added, the strength and hardness of the composite material gradually increased (Examples 1 to 3), while the plasticity decreased accordingly. Among them, Example 2 achieved an excellent elongation of 8.0% while maintaining a high tensile strength of 1380 MPa, demonstrating the best strength-plasticity match and representing the preferred embodiment of the present invention. This indicates that by controlling the content of the reinforcing phase, composite materials that meet different performance requirements can be obtained, and for most structural applications, the composition ratio represented by Example 2 achieves the optimal combination of high strength and high toughness.

[0078] The samples from Example 2, Comparative Example 1, and Comparative Example 2 were subjected to high-temperature tensile tests at 600°C, and their creep life under the conditions of 600°C / 200MPa was tested. The results are shown in Table 2 below.

[0079] Table 2 High Temperature Tensile Test Data

[0080] As shown in Table 2, Example 2 exhibits the best high-temperature strength and creep resistance. This is attributed to: 1) the highly thermally stable nano-LaB6 core can still effectively support the load at high temperatures; 2) the gradient interface structure remains stable at high temperatures; and 3) the in-situ generated reinforcing phase effectively pins the grain boundaries. Comparative Examples 1 and 2, lacking a strengthening mechanism, show significantly inferior high-temperature performance.

[0081] The samples from Example 2 and Comparative Example 1 were processed to specified dimensions and placed in a muffle furnace for 100-500 hours of exposure in an air atmosphere at 600-800°C. The weight gain per unit area was then measured, and the surface morphology and cross-sectional structure of the oxide film were observed using a scanning electron microscope. The test results showed that after 500 hours / 800°C oxidation, the weight gain per unit area of ​​Example 2 was reduced by more than 50% compared to Comparative Example 1. The oxide film of Comparative Example 1 was thick and porous, with poor adhesion to the substrate, and easily peeled off; while the oxide film of Example 2 was thinner, denser, and had good adhesion to the substrate.

[0082] The composite powders or small blocks of Example 2 and Comparative Example 2 (conventional sintering, structural runaway) were tested using DSC. Under argon protection, they were heated from room temperature to above 1200°C at a certain heating rate (e.g., 20°C / min), and their heat flow profiles were analyzed. Figure 9 As shown in the DSC curves, Comparative Example 2 exhibits a sharp exothermic peak at approximately 900°C, corresponding to the intense and disordered exothermic reaction between LaB6 and Ti. In contrast, the curve for Example 2 shows only a broadened and gentle exothermic plateau in this temperature range.

[0083] like Figure 10 , Figure 11 , Figure 12 , Figure 13 , Figure 14 As shown, using XPS depth profiling results, chemical state analysis was performed on the nano-lanthanum hexaboride reinforced titanium matrix composite material prepared in Example 2 at different sputtering depths (5-80 nm). The results clearly revealed the evolution law of chemical composition and chemical state gradient from the surface of the material to the Ti matrix, directly confirming that sufficient element diffusion and complex in-situ chemical reactions occurred between the LaB6 reinforcing phase and the Ti matrix, ultimately forming a well-defined gradient transition layer. Specifically, the material surface (5nm) forms a natural oxide layer of TiO2 (Ti2p=458.5eV) and B2O3 (B1s=192.0eV) due to exposure to air, which is a normal surface state of the metallic material; significant enrichment of La2O3 nanoparticles appears in the near-interface region (15nm) (La3d=834.2eV, signal intensity reaches peak); in the transition region (30nm), Ti and B undergo in-situ reaction to form TiB whiskers (Ti2p=454.8eV, B1s=188.2eV); and the internal region (50nm) retains incompletely reacted LaB6 cores (La3d=836.0eV, B1s=188.0eV). The continuous change in the chemical states of the elements is particularly significant: Ti2p gradually shifts from 458.5 eV at the surface TiO2 to 453.9 eV at the matrix metal Ti; La transforms from La2O3 at the interface to LaB6 in the interior; and B undergoes an orderly transition between the oxidized and reactive states. Furthermore, O is mainly concentrated in the surface oxide layer and the La2O3-enriched region at the interface, with extremely low content in the interior. These results not only fully record the in-situ reaction process between LaB6 and the Ti matrix but also directly confirm the core characteristics of "in-situ reaction forming a gradient transition layer" and "interfacial enrichment of La2O3 particles," providing a solid chemical state characterization basis for the interfacial structure design and performance optimization of composite materials.

[0084] This invention addresses the problems of existing nano-lanthanum hexaboride-reinforced titanium matrix composites, such as the reinforcing phase's tendency to agglomerate due to high surface energy, weak interfacial bonding with the titanium matrix, inverted strong-plasticity relationship, insufficient antibacterial properties, and failure to meet theoretical expectations in terms of plasticity, toughness, strength, and reliability. It employs a combination of low-energy mixing and spark plasma sintering processes. By precisely controlling the pulse current (pulse width and interval) and hot-pressing parameters, a controllable in-situ reaction is induced between nano-lanthanum hexaboride and the titanium matrix. This constructs a composite reinforcement with an incompletely reacted nano-lanthanum hexaboride core and a gradient reaction layer (containing a La / B-rich amorphous transition region and a TiB whisker layer) forming a shell with continuously varying composition and structure. The core-shell structure fundamentally isolates particles from direct contact to inhibit agglomeration and ensure uniform dispersion. The gradient transition layer can relax interfacial stress, passivate microcracks, and achieve efficient load transfer, thus synergistically resolving the contradiction between strong plasticity. At the same time, the nano-La2O3 particles precipitated in situ during sintering achieve dispersion strengthening and grain refinement by pinning grain boundaries and hindering dislocation movement. Furthermore, the introduction of La element endows the material with antibacterial properties. Subsequent hot extrusion treatment further eliminates residual porosity and optimizes the microstructure. Ultimately, through multi-scale and multi-mechanism synergistic strengthening, the composite material's strength, hardness, wear resistance, creep resistance, and antibacterial properties at room temperature and high temperature are comprehensively improved.

[0085] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A nano-lanthanum hexaboride reinforced titanium-based composite material, characterized in that, The composite material includes: Titanium alloy matrix; and A composite reinforcement uniformly dispersed in the titanium alloy matrix; wherein, The composite reinforcement has a core-shell structure, wherein the core of the core-shell structure is a nano-lanthanum hexaboride particle, and the shell layer of the core-shell structure is an in-situ reaction layer covering the outer surface of the nano-lanthanum hexaboride particle. The in-situ reaction layer is a transition layer with a gradient in composition and structure, and the transition layer includes at least a La / B rich amorphous transition region and a TiB whisker layer distributed from the inside to the outside.

2. The nano-lanthanum hexaboride reinforced titanium-based composite material according to claim 1, characterized in that, The composite reinforcement is enriched with La2O3 particles at the phase interface between the composite reinforcement and the titanium alloy matrix. The La2O3 particles are smaller than 100 nm in size and are preferentially distributed at the interface between the TiB whiskers and the titanium alloy matrix.

3. The nano-lanthanum hexaboride reinforced titanium-based composite material according to claim 1, characterized in that, The average particle size of the nano-lanthanum hexaboride particles is 50nm-200nm; the average diameter of the TiB whiskers is less than 500nm, and the aspect ratio is greater than 3.

4. The nano-lanthanum hexaboride reinforced titanium-based composite material according to claim 1, characterized in that, The content of the nano-lanthanum hexaboride particles is from 0.1 wt.% to 2.0 wt.%; the content of the TiB whiskers is from 0.5 wt.% to 8.0 wt.%.

5. The nano-lanthanum hexaboride reinforced titanium-based composite material according to claim 1, characterized in that, The titanium alloy matrix is ​​TC4 alloy, TC11 alloy, or Ti-Al-Mo-V-Cr β-type titanium alloy.

6. A method for preparing a nano-lanthanum hexaboride-reinforced titanium-based composite material according to any one of claims 1-5, characterized in that, Includes the following steps: S1: Obtain titanium alloy powder and nano-lanthanum hexaboride powder; S2: The titanium alloy powder and nano lanthanum hexaboride powder are mechanically mixed under inert gas protection, wherein the mechanical mixing is performed by low-energy ball milling or three-dimensional mixing machine, so that the nano lanthanum hexaboride powder is uniformly attached to the surface of the titanium alloy powder to obtain composite powder. S3: The composite powder is subjected to spark plasma sintering. By controlling the pulse current parameters and hot pressing parameters of the sintering, the nano-lanthanum hexaboride particles and the titanium alloy matrix are induced to undergo an interfacial reaction, generating a gradient interfacial structure in situ, and obtaining a dense composite material blank.

7. The method for preparing a nano-lanthanum hexaboride-reinforced titanium-based composite material according to claim 6, characterized in that, In step S3, the process parameters for the discharge plasma sintering are: sintering temperature of 900℃-1200℃, sintering pressure of 30MPa-60MPa, and holding time of 5-20 minutes.

8. The method for preparing a nano-lanthanum hexaboride-reinforced titanium-based composite material according to claim 6, characterized in that, The pulse current is a DC pulse, and the pulse mode is: pulse width of 0.1ms-20ms and pulse interval of 0.1ms-20ms.

9. The method for preparing a nano-lanthanum hexaboride-reinforced titanium-based composite material according to claim 6, characterized in that, After step S3, step S4 is also included: hot extrusion treatment of the composite material preform, with an extrusion ratio of 8:1 to 15:1 and an extrusion temperature of 900℃-1000℃.

10. A component, characterized in that, The component is made by forming and processing from the nano-lanthanum hexaboride reinforced titanium-based composite material as described in any one of claims 1-5.

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