High-modulus high-toughness titanium-based composite material and preparation method thereof

Abstract

The invention belongs to the technical field of titanium-based composite material preparation, and particularly relates to a high-modulus and high-toughness titanium-based composite material and a preparation method thereof.The preparation method of the high-modulus and high-toughness titanium-based composite material comprises the steps that sodium borohydride and graphene serve as raw material powder to prepare functionalized boron alkene-graphene composite powder; dissolving titanium powder and the functionalized boron alkene-graphene composite powder in an alcohol solvent by adopting a wet mixing process, and filtering and drying the obtained mixed slurry to obtain boron alkene-graphene-titanium composite powder; and selective laser melting forming is conducted on the boron alkene-graphene-titanium composite powder through the LPBF technology, and the high-modulus and high-toughness titanium-based composite material is prepared. According to the preparation method of the high-modulus and high-toughness titanium-based composite material, graphene is subjected to boron alkene modification, and an LPBF process is combined, so that the complete lattice structure of graphene is kept while uniform dispersion of graphene in powder is guaranteed, and the excellent intrinsic strengthening effect of graphene is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of titanium matrix composites, and particularly relates to a high-modulus and high-strength and tough titanium matrix composite and a preparation method thereof. Background Art

[0002] Currently, the strengthening method of titanium matrix composites is usually to introduce external ceramic particles, and the comprehensive mechanical properties of the composites are improved by load transfer, fine grain strengthening, solid solution strengthening, and thermal mismatch strengthening, etc. However, with the continuous development of industries such as aerospace, the current titanium matrix composites can no longer meet the requirements, and it is necessary to further prepare titanium matrix composites with higher performance. Graphene, as a current revolutionary two-dimensional nanomaterial, shows great potential in the field of composite material strengthening. First, its single-atom layer structure can achieve an elastic modulus of up to 1 TPa and a theoretical strength of 130 GPa, and the strengthening efficiency per unit mass is 6-8 times that of traditional SiC particles; second, the ultra-large specific surface area (2630 m 2 / g) forms a strong interfacial bond with the titanium matrix, and through the two-dimensional in-plane load transfer mechanism, the strength and plasticity of the material can be improved simultaneously; third, the diamond-like sp 2 hybrid structure endows it with excellent thermal conductivity (5000 W / mK), which can significantly improve the thermal stability of the composite material. However, it currently faces two major technical challenges: first, the agglomeration phenomenon caused by high surface energy will lead to uneven distribution of the reinforcement; second, the affinity between carbon and titanium is relatively high, and the violent reaction between carbon and titanium during the preparation process will generate an excessive amount of brittle TiC phase, which will not only damage the complete lattice of graphene but also seriously deteriorate the plasticity.

[0003] Traditional hot working processes have an essential limitation in the preparation of graphene-reinforced titanium matrix composites - the diffusion coefficient of carbon atoms will increase sharply during long-term high-temperature exposure, leading to the instability of the triple structure: first, the dangling bonds at the edge of graphene react violently with titanium atoms to form a brittle TiC transition layer with a thickness of 3 μm - 5 μm; second, the matrix grains grow abnormally under the action of long-term high temperature, and the resistance to dislocation movement decreases; more seriously, the two-dimensional continuous structure of graphene is divided and damaged by the island-like TiC formed by the reaction, completely losing its intrinsic strengthening advantage.

[0004] Therefore, in view of the above deficiencies, the present invention is specifically proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-modulus and high-strength and tough titanium matrix composite and a preparation method thereof. Compared with traditional processes, in the preparation method of the high-modulus and high-strength and tough titanium matrix composite of the present invention, the graphene is modified with borophene and combined with the LPBF process to ensure that the graphene is evenly dispersed in the powder while retaining its complete lattice structure, so as to exert its excellent intrinsic strengthening effect.

[0006] The first aspect of the present invention provides a method for preparing a high-modulus and high-strength titanium-based composite material. The preparation method includes: preparing a functionalized borophene-graphene composite powder from sodium borohydride and graphene as raw material powders; using a wet mixing process to dissolve titanium powder and the functionalized borophene-graphene composite powder in an alcohol solvent, and performing first filtration and first drying on the obtained mixed slurry to obtain a borophene-graphene-titanium composite powder; using LPBF technology to perform selective laser melting forming on the borophene-graphene-titanium composite powder to prepare the high-modulus and high-strength titanium-based composite material.

[0007] In some embodiments of the present invention, the process parameters of the selective laser melting forming include: a powder spreading speed of 0.04 mm / s to 0.08 mm / s, a laser power of 240 W to 300 W, a scanning speed of 1800 mm / s to 2000 mm / s, and a scanning spacing of 0.10 mm to 0.14 mm.

[0008] In some embodiments of the present invention, the preparation of the functionalized borophene-graphene composite powder includes: performing segmented heating and calcination on the mixed powder of the sodium borohydride and the graphene, and placing the calcined product in an ethanol solution, followed by second filtration and second drying to prepare the functionalized borophene-graphene composite powder.

[0009] In some embodiments of the present invention, the mass ratio of the graphene to the sodium borohydride is 1:(1 to 4).

[0010] In some embodiments of the present invention, the mass ratio of the graphene to the sodium borohydride is 1:(2 to 4);

[0011] In some embodiments of the present invention, the second drying temperature is 60°C to 80°C, and the second drying time is 3 h to 5 h.

[0012] In some embodiments of the present invention, three-stage heating and calcination is adopted. Among them, the first-stage calcination temperature is 460°C to 490°C, and the calcination time is 2 h to 2.5 h; the second-stage calcination temperature is 530°C to 550°C, and the calcination time is 0.5 h to 1 h; the third-stage calcination temperature is 600°C to 650°C, and the calcination time is 0.5 h to 1 h.

[0013] In some embodiments of the present invention, the heating rate of the first-stage calcination is 10°C / min to 15°C / min; and / or, the heating rate of the second-stage calcination is 5°C / min to 10°C / min; and / or, the heating rate of the third-stage calcination is 5°C / min to 10°C / min.

[0014] In some embodiments of the present invention, the mixed slurry is subjected to ultrasonic vibration and / or mechanical stirring before the first filtration.

[0015] In some embodiments of the present invention, the time of ultrasonic vibration is 30 min to 60 min, and the time of mechanical stirring is 30 min to 60 min.

[0016] In some embodiments of the present invention, the temperature of the first drying is 400 °C to 500 °C, and the time of the first drying is 5 h to 7 h.

[0017] In some embodiments of the present invention, based on the mass of the boronene-graphene-titanium composite powder, the mass percentage of the functionalized boronene-graphene composite powder is 0.5 wt% to 3 wt%.

[0018] The second aspect of the present invention provides a high modulus and high strength and toughness titanium matrix composite material, which is prepared by using the preparation method described in the first aspect.

[0019] In some embodiments of the present invention, the relative density of the high modulus and high strength and toughness titanium matrix composite material is ≥ 99%, the tensile strength is 1300 MPa to 1500 MPa, the elongation is 2.0% to 5.0%, and the Young's modulus is 130 GPa to 155 GPa.

[0020] The present invention improves the dispersion degree of graphene on the powder surface through non-destructive modification of graphene and uses selective laser melting technology for forming. Through powder modification combined with the high cooling rate of the LPBF process, the interfacial reaction between graphene and the titanium matrix is reduced, the integrity of the graphene lattice is retained to the greatest extent, and the intrinsic strengthening effect of graphene is exerted.

[0021] The present invention first deposits boronene on the surface of graphene and performs functionalization treatment, which can indirectly increase oxygen-containing functional groups on the powder surface without destroying the lattice structure of graphene. This process avoids the damage effect of high-energy ball milling and chemical modification on graphene, effectively improves the dispersion ability of the powder in aqueous solution and enhances its dispersibility while maintaining the integrity of the graphene lattice. Secondly, compared with other processes, using the LPBF process with extremely high heating and cooling rates can further reduce the interfacial reaction degree between graphene and the titanium matrix, retain the integrity of graphene, and at the same time refine the grain size and the size of the reinforcing particles, which is beneficial to constructing a nano-scale configuration in the matrix. Based on the synergistic strengthening of the comprehensive mechanical properties of the titanium matrix composite material from two aspects of optimizing the powder and optimizing the configuration, the goal of high modulus and high strength and toughness performance is achieved. Description of the Drawings

[0022] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0023] Figure 1 It is the morphology diagram of graphene powder.

[0024] Figure 2 It is the morphology diagram of sodium borohydride powder.

[0025] Figure 3 It is the morphology diagram of the functionalized borophene-graphene composite powder prepared in the embodiment of the present invention.

[0026] Figure 4 It is the morphology diagram of the borophene-graphene-titanium composite powder with an enhancement ratio of 0.5 wt% prepared in Example 1 of the present invention.

[0027] Figure 5 It is the microstructure morphology of the borophene-graphene reinforced titanium matrix composite with an enhancement ratio of 0.5 wt% prepared in Example 1 of the present invention.

[0028] Figure 6 It is the morphology diagram of the borophene-graphene-titanium composite powder with an enhancement ratio of 1.5 wt% prepared in Example 2 of the present invention.

[0029] Figure 7 It is the microstructure morphology of the borophene-graphene reinforced titanium matrix composite with an enhancement ratio of 1.5 wt% prepared in Example 2 of the present invention.

[0030] Figure 8 It is the morphology diagram of the borophene-graphene-titanium composite powder with an enhancement ratio of 3.0 wt% prepared in Example 3 of the present invention.

[0031] Figure 9 It is the microstructure morphology of the borophene-graphene reinforced titanium matrix composite with an enhancement ratio of 3.0 wt% prepared in Example 3 of the present invention.

[0032] Figure 10 It is the test results of the mechanical properties of the borophene-graphene reinforced titanium matrix composites with three enhancement ratios in Examples 1-3 of the present invention.

[0033] Figure 11 It is the scanning electron microscope image of the graphene-titanium composite powder with an enhancement ratio of 0.5 wt% prepared in Comparative Example 1 of the present invention.

[0034] Figure 12SEM image of the graphene-titanium composite powder with an enhancement ratio of 1.5 wt% prepared in Comparative Example 2 of the present invention.

[0035] Figure 13 SEM image of the graphene-titanium composite powder with an enhancement ratio of 3.0 wt% prepared in Comparative Example 3 of the present invention. Detailed implementation manners

[0036] The exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided so that the present invention can be more thoroughly understood and the scope of the present invention can be fully conveyed to those skilled in the art.

[0037] It should be understood that the terms used herein are only for the purpose of describing specific exemplary embodiments and are not intended to be limiting. Unless otherwise clearly specified in the context, the singular forms "a", "an", and "the" as used herein may also include the plural forms. The terms "comprising", "including", "containing", and "having" are inclusive and thus specify the presence of the stated features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring them to be executed in the specific order described or illustrated, unless the execution order is explicitly stated. It should also be understood that additional or alternative steps may be used.

[0038] In the description of the embodiments of the present invention, the technical terms "first", "second", etc. are only used to distinguish different objects and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity, specific order, or primary-secondary relationship of the indicated technical features. In the description of the embodiments of the present invention, "a plurality" means two or more unless otherwise explicitly and specifically defined.

[0039] Referring to "embodiments" herein means that the specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the present invention. The phrase appears at various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0040] In the description of the embodiments of the present invention, the term "and / or" is merely a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0041] In the description of the embodiments of the present invention, the term "plurality" refers to two or more (including two). Similarly, "multiple groups" refers to two or more groups (including two groups), and "multiple pieces" refers to two or more pieces (including two pieces).

[0042] Traditional hot processing technology faces essential limitations in the preparation of graphene-reinforced titanium matrix composites. Prolonged high-temperature exposure will cause a sharp increase in the carbon atom diffusion coefficient, leading to the instability of the triple structure. First, the dangling bonds at the edge of graphene react violently with titanium atoms to form a brittle TiC transition layer with a thickness of 3μm to 5μm. Second, the matrix grains grow abnormally under the action of long-term high temperature, and the dislocation movement resistance decreases. More seriously, the two-dimensional continuous structure of graphene is divided and destroyed by the island-shaped TiC formed by the reaction, completely losing its intrinsic strengthening advantage.

[0043] Laser powder bed fusion (LPBF) technology provides a new idea for solving the above problems. The rapid melting and solidification characteristics of its high-energy laser beam (the cooling rate can reach 103K / s to 108K / s) can effectively avoid the performance deterioration caused by long-term high-temperature exposure. After shortening the high-temperature residence time to the millisecond level, the interfacial reaction between graphene and the titanium matrix can be significantly inhibited. Moreover, the ultra-high temperature gradient (106K / min) can induce the in-situ generation of nano-sized TiC particles, improving the integrity of graphene while obtaining nano-sized reinforcement particles, providing new opportunities for customizing the nano-scale microstructure of titanium matrix composites. By optimizing the laser parameters in the present invention, the thickness of the carbon-titanium reaction layer can be controlled within 1 micron. At the same time, the Marangoni convection inside the molten pool can also promote the dispersion of graphene powder.

[0044] The present invention uses LPBF technology combined with graphene to prepare high-modulus, high-strength and tough titanium matrix composites, which is expected to break through the current bottleneck of high-modulus, high-strength and tough performance of titanium matrix composites.

[0045] The present invention first provides a method for preparing a high-modulus and high-strength titanium-based composite material. The key to this preparation method lies in preparing a functionalized borophene-graphene composite powder using sodium borohydride and graphene as raw material powders; dissolving titanium powder and the functionalized borophene-graphene composite powder in an alcohol solvent by a wet mixing process, and filtering and drying the obtained mixed slurry to obtain a borophene-graphene-titanium composite powder; using LPBF technology to selectively laser melt and form the borophene-graphene-titanium composite powder to prepare a high-modulus and high-strength titanium-based composite material.

[0046] The method for preparing the high-modulus and high-strength titanium-based composite material in the present invention is specifically carried out according to the following steps.

[0047] Preparing a functionalized borophene-graphene composite powder

[0048] 1) Raw material powders

[0049] In the embodiments of the present invention, graphene and sodium borohydride are used as raw material powders. Under a protective atmosphere, such as an argon protection environment, the two powders are mixed together according to the target mass ratio, and then the mixed powder is placed inside a firing boat and vacuum-sealed.

[0050] In some embodiments of the present invention, the original graphene powder prepared by a physical method and analytical pure sodium borohydride are used as raw material powders.

[0051] In some embodiments of the present invention, the mass ratio of graphene to sodium borohydride is 1:(1 - 4). The mass ratio of graphene to sodium borohydride provided by the present invention can be any value within the range formed by any two values within the above range. For example, it can be 1:(1 - 2), or it can be 1:(2 - 4), and so on. Exemplarily, the mass ratio of graphene to sodium borohydride can also be one of 1:1, 1:2, 1:3, 1:4 or any value that satisfies the above range.

[0052] In some embodiments of the present invention, the protective atmosphere can be one of an argon atmosphere and a nitrogen atmosphere. For example, the mixing of the raw material powders is carried out under an argon environment.

[0053] In some embodiments of the present invention, the mixed powder can be placed inside a firing boat under a protective atmosphere according to the actual situation, and then the firing boat is placed in a vacuum bag and sealed to prevent sodium borohydride from oxidizing and deliquescing in the air.

[0054] 2) Heating and calcining

[0055] In the embodiments of the present invention, under a protective atmosphere, such as an argon atmosphere or a nitrogen atmosphere, the mixed powder is heated and calcined in a segmented manner and cooled with the furnace to obtain a calcined product.

[0056] In some embodiments of the present invention, the mixed powder is placed in a firing boat and subjected to staged heating and calcination in a tubular furnace under a protective atmosphere to modify graphene.

[0057] In some embodiments of the present invention, three-stage heating and calcination is adopted. The first-stage calcination temperature is 460°C to 490°C, and the calcination time is 2h to 2.5h; the second-stage calcination temperature is 530°C to 550°C, and the calcination time for this stage is 0.5h to 1h; the third-stage calcination temperature is 600°C to 650°C, and the calcination time is 0.5h to 1h.

[0058] Exemplarily, the first-stage calcination temperature can be one of 460°C, 465°C, 470°C, 475°C, 480°C, 485°C, 490°C or any value satisfying the above range. The first-stage calcination time can be one of 2h, 2.1h, 2.2h, 2.3h, 2.4h, 2.5h or any value satisfying the above range.

[0059] Exemplarily, the second-stage calcination temperature can be one of 530°C, 535°C, 540°C, 545°C, 550°C or any value satisfying the above range. The second-stage calcination time can be one of 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h or any value satisfying the above range.

[0060] Exemplarily, the third-stage calcination temperature can be one of 600°C, 605°C, 610°C, 615°C, 620°C, 625°C, 630°C, 635°C, 640°C, 645°C, 650°C or any value satisfying the above range. The third-stage calcination time can be one of 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h or any value satisfying the above range.

[0061] In some embodiments of the present invention, the heating rate of the first-stage calcination is 10°C / min to 15°C / min. Exemplarily, the heating rate of the first-stage calcination can be one of 10°C / min, 11°C / min, 12°C / min, 13°C / min, 14°C / min, 15°C / min or any value satisfying the above range.

[0062] In some embodiments of the present invention, the heating rate of the second-stage calcination is 5°C / min to 10°C / min. Exemplarily, the heating rate of the second-stage calcination can be one of 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min or any value satisfying the above range.

[0063] In some embodiments of the present invention, the heating rate of the third stage calcination is 5°C / min to 10°C / min. For example, the heating rate of the third stage calcination can be one of 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, or any value satisfying the above range.

[0064] In some embodiments of the present invention, sodium borohydride and graphene are mixed uniformly in an argon environment at a weight ratio of (1 to 4): 1, and the mixed powder is subjected to three-stage heating calcination to promote the in-situ thermal decomposition of sodium borohydride and cover the graphene surface with a layer of boronene. The specific heating calcination parameters are: first, the temperature is raised to 460°C to 490°C at a heating rate of 10°C / min to 15°C / min, and the temperature is kept at this temperature for 2h to 2.5h for the first stage of calcination; secondly, the temperature is raised to 530°C to 550°C at a heating rate of 5°C / min to 10°C / min, and the temperature is kept at this temperature for 0.5h to 1h for the second stage of calcination; finally, the temperature is raised to 600°C to 650°C at a heating rate of 5°C / min to 10°C / min, and the temperature is kept at this temperature for 0.5h to 1h for the third stage of calcination. After the insulation is completed, the calcined product is naturally cooled to room temperature with the furnace.

[0065] It is worth mentioning that room temperature refers to a state where the temperature is between 20℃ and 30℃ without active heating or cooling.

[0066] 3) Removal of sodium

[0067] In an embodiment of the present invention, the calcined product is placed in an ethanol solution to remove the sodium element in the calcined product, and at the same time, the boron surface is functionalized to introduce oxygen-containing functional groups such as hydroxyl groups to improve the hydrophilicity of the composite powder.

[0068] In some embodiments of the present invention, in order to improve the removal effect of sodium and achieve the effect of preliminary dispersion, the calcined product can be placed in an ethanol solution and subjected to a third ultrasonic vibration and / or a third mechanical stirring at the same time according to actual needs.

[0069] In some embodiments of the present invention, the third ultrasonic vibration time is 0.5h to 1h. For example, the third ultrasonic vibration time can be one of 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h or any value within the above range.

[0070] In some embodiments of the present invention, the frequency of the third ultrasonic vibration is 40kHz to 50kHz. For example, the frequency of the third ultrasonic vibration can be one of 40kHz, 41kHz, 42kHz, 43kHz, 44kHz, 45kHz, 46kHz, 47kHz, 48kHz, 49kHz, 50kHz or any value that meets the above range.

[0071] In some embodiments of the present invention, the third mechanical stirring time is 0.5h to 1h, and the rotation speed is 300rpm to 400rpm. Exemplarily, the third mechanical stirring time can be one of 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h or any value satisfying the above range value. The rotation speed of the third mechanical stirring can be one of 300rpm, 310rpm, 320rpm, 330rpm, 340rpm, 350rpm, 360rpm, 370rpm, 380rpm, 390rpm, 400rpm or any value satisfying the above range value.

[0072] In some embodiments of the present invention, the calcined product obtained after calcination is placed in an ethanol solution, and treated by a third ultrasonic vibration and a third mechanical stirring method for 0.5h to 1h, respectively, to remove the sodium element in the material and disperse the graphene powder modified by borophene. At the same time, in this process, due to the electron-deficient characteristics of boron itself, the hydroxyl functional group in anhydrous ethanol can also open the boron element energy band, combine with borophene, and improve the overall dispersion ability of the powder in the aqueous solution.

[0073] In some embodiments of the present invention, a Branson 450D disperser with a frequency of 40kHz to 50kHz is used for the third ultrasonic vibration treatment, and an IKARW20 mechanical stirrer with a rotation speed of 300rpm to 400rpm is used for continuous stirring for 30min to 60min to remove the sodium element in the material and disperse the boron-modified graphene powder.

[0074] 4) Filtration and drying

[0075] In an embodiment of the present invention, the composite powder slurry obtained by dissolving the calcined product in an ethanol solution is subjected to a second filtration and a second drying process to obtain a functionalized borophene-graphene composite powder, see Figure 3 shown.

[0076] In some embodiments of the present invention, the temperature of the second drying is 60°C to 80°C, and the time of the second drying is 3h to 5h. Exemplarily, the temperature of the second drying can be one of 60°C, 65°C, 70°C, 75°C, 80°C or any value satisfying the above range. The time of the second drying can be one of 3h, 4h, 5h or any value satisfying the above range.

[0077] In some embodiments of the present invention, a vacuum drying oven is used for the second drying treatment, and drying is carried out at 60°C to 80°C for 3h to 5h to obtain functionalized borophene-graphene composite powder.

[0078] Prepare borophene-graphene-titanium composite powder

[0079] In an embodiment of the present invention, a wet mixing process is used to dissolve titanium powder and functionalized borophene-graphene composite powder in an alcohol solvent, and the obtained mixed slurry is subjected to first filtration and first drying to obtain borophene-graphene-titanium composite powder.

[0080] 1) Prepare functionalized borophene-graphene composite powder slurry

[0081] In an embodiment of the present invention, the functionalized borophene-graphene composite powder is placed in an alcohol solvent and subjected to first ultrasonic vibration and / or first mechanical stirring to obtain a functionalized borophene-graphene composite powder slurry.

[0082] In some embodiments of the present invention, the functionalized borophene-graphene composite powder is placed in an ethanol solution to improve the overall hydrophilicity of the powder, thereby laying a foundation for subsequent adsorption on the surface of titanium powder to improve its lattice integrity.

[0083] In some embodiments of the present invention, the alcohol solvent is selected from ethanol.

[0084] In some embodiments of the present invention, the ultrasonic vibration treatment time of the functionalized borophene-graphene composite powder can be 0.5h to 1h. Exemplarily, the ultrasonic vibration time of the functionalized borophene-graphene composite powder can be one of 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h or any value satisfying the above range.

[0085] In some embodiments of the present invention, the mechanical stirring time of the functionalized borophene-graphene composite powder can be 0.5h to 1h. Exemplarily, the mechanical stirring time of the functionalized borophene-graphene composite powder can be one of 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h or any value satisfying the above range.

[0086] 2) Prepare titanium powder slurry

[0087] In an embodiment of the present invention, titanium powder is placed in an alcohol solvent, and first ultrasonic vibration and / or first mechanical stirring are performed to obtain a titanium powder slurry.

[0088] In some embodiments of the present invention, the alcohol solvent is selected from ethanol.

[0089] In some embodiments of the present invention, the ultrasonic vibration treatment time of the titanium powder can be 0.5 h to 1 h. Exemplarily, the ultrasonic vibration time of the titanium powder can be one of 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, 1 h or any value satisfying the above range value.

[0090] In some embodiments of the present invention, the mechanical stirring time of the titanium powder can be 0.5 h to 1 h. Exemplarily, the mechanical stirring time of the titanium powder can be one of 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, 1 h or any value satisfying the above range value.

[0091] 3) Mixed slurry

[0092] In an embodiment of the present invention, the functionalized boronene-graphene composite powder slurry is mixed with the titanium powder slurry, and second ultrasonic vibration and / or second mechanical stirring are performed to fully mix to obtain a mixed slurry.

[0093] In some embodiments of the present invention, after the functionalized boronene-graphene composite powder slurry and the titanium powder slurry are mixed, second ultrasonic vibration is performed for 0.5 h to 1 h, and second mechanical stirring is performed for 0.5 h to 1 h to promote the adsorption of graphene on the surface of the titanium powder. Exemplarily, the second ultrasonic vibration time can be one of 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, 1 h or any value satisfying the above range value. The second mechanical stirring time can be one of 0.5 h, 0.6 h, 0.7 h, 0.8 h, 0.9 h, 1 h or any value satisfying the above range value.

[0094] In some embodiments of the present invention, a Branson 450D disperser is used, with a frequency of 40 kHz to 50 kHz, lasting for 30 min to 60 min, and at the same time, an IKA RW20 mechanical stirrer is used, with a rotation speed of 300 rpm to 400 rpm, lasting for 30 min to 60 min.

[0095] In some embodiments of the present invention, first, the functionalized borophene-graphene composite powder and titanium powder are independently dispersed into an ethanol solution according to the required weight ratio, and are independently subjected to ultrasonic vibration treatment for 0.5 h to 1 h and mechanical stirring for 0.5 h to 1 h; then the two obtained slurries are mixed together, and after mixing, ultrasonic vibration for 0.5 h to 1 h and mechanical stirring for 0.5 h to 1 h are performed again to promote the adsorption of graphene on the surface of titanium powder.

[0096] In some embodiments of the present invention, powdering is carried out by a wet mixing process. Specifically, the functionalized borophene-graphene composite powder and spherical titanium powder are independently dispersed into an ethanol solution according to the target weight ratio, and after independently performing ultrasonic vibration for 0.5 h to 1 h, the functionalized borophene-graphene composite powder slurry and the titanium powder slurry are mixed. Subsequently, the mixed slurry is simultaneously subjected to ultrasonic vibration and mechanical stirring for 0.5 h to 1 h to enhance the adhesion effect of the modified graphene on the powder surface.

[0097] In some embodiments of the present invention, based on the mass of the borophene-graphene-titanium composite powder, the mass percentage of the functionalized borophene-graphene composite powder is 0.5 wt% to 3 wt%. Exemplarily, the mass percentage of the functionalized borophene-graphene composite powder can be one of 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.2 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.8 wt%, 2 wt%, 2.2 wt%, 2.4 wt%, 2.5 wt%, 2.6 wt%, 2.8 wt%, 3 wt% or any value satisfying the above range.

[0098] 4) Filtration and drying

[0099] In the embodiments of the present invention, the mixed slurry is subjected to first filtration and first drying to obtain the borophene-graphene-titanium composite powder.

[0100] In some embodiments of the present invention, the temperature of the first drying is 400 °C to 500 °C, and the time of the first drying is 5 h to 7 h. Exemplarily, the temperature of the first drying can be one of 400 °C, 450 °C, 500 °C or any value satisfying the above range. The time of the first drying can be one of 5 h, 6 h, 7 h or any value satisfying the above range.

[0101] In some embodiments of the present invention, the first drying is carried out using a vacuum drying oven, and drying is carried out at 400 °C to 500 °C for 5 h to 7 h to obtain the borophene-graphene-titanium composite powder.

[0102] In some embodiments of the present invention, after wet mixing and powder coating, the mixed slurry is subjected to a first filtration, and then subjected to a first drying at 450°C to 500°C in a vacuum drying oven for 5h to 7h. While drying the powder, the oxygen-containing functional groups introduced in the previous functionalization operation are removed to reduce the oxygen content of the powder.

[0103] Selective laser melting forming

[0104] In an embodiment of the present invention, the selective laser melting forming of the boronene-graphene-titanium composite powder is carried out by using the LPBF technology, that is, the boronene-graphene-titanium composite powder is scanned layer by layer for selective laser melting forming to obtain a high-modulus and high-strength and tough titanium matrix composite material.

[0105] In some embodiments of the present invention, the process parameters of the selective laser melting forming include: the powder spreading speed is 0.04 mm / s to 0.08 mm / s, the laser power is 240 W to 300 W, the scanning speed is 1800 mm / s to 2000 mm / s, and the scanning spacing is 0.10 mm to 0.14 mm.

[0106] Exemplarily, the powder spreading speed can be one of 0.04 mm / s, 0.05 mm / s, 0.06 mm / s, 0.07 mm / s, 0.08 mm / s or any value satisfying the above range. The laser power can be one of 240 W, 250 W, 260 W, 270 W, 280 W, 290 W, 300 W or any value satisfying the above range. The scanning speed can be one of 1800 mm / s, 1900 mm / s, 2000 mm / s or any value satisfying the above range. The scanning spacing can be one of 0.10 mm, 0.11 mm, 0.12 mm, 0.13 mm, 0.14 mm or any value satisfying the above range.

[0107] In some embodiments of the present invention, the selective laser melting forming of the boronene-graphene-titanium composite powder is carried out by using the LPBF technology, and the process parameters are set as follows: the powder spreading speed is 0.06 mm / s, the laser power is 280 W, the scanning speed is 2000 mm / s, and the scanning spacing is 0.12 mm.

[0108] The present invention also provides a high-modulus and high-strength and tough titanium matrix composite material, which is prepared by using the above preparation method.

[0109] In an embodiment of the present invention, the relative density of the high-modulus and high-strength and tough titanium matrix composite material is ≥99%, the tensile strength is 1300 MPa to 1500 MPa, the elongation is 2.0% to 5.0%, and the Young's modulus is 130 GPa to 155 GPa.

[0110] Exemplarily, the tensile strength of the high modulus and high strength and toughness titanium-based composite material can be one of 1300 MPa, 1320 MPa, 1347 MPa, 1350 MPa, 1360 MPa, 1373 MPa, 1380 MPa, 1390 MPa, 1400 MPa, 1410 MPa, 1420 MPa, 1430 MPa, 1440 MPa, 1450 MPa, 1460 MPa, 1471 MPa, 1480 MPa, 1490 MPa, and 1500 MPa, or any value that meets the above range.

[0111] Exemplarily, the elongation of the high modulus and high strength and toughness titanium-based composite material can be 2.0%, 2.1%, 2.2%, 2.3%, 2.47%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0%, 3.2%, 3.4%, 3.5%, 3.6%, 3.8%, 4.0%, 4.2%, 4.4%, 4.47%, 4.5%, 4.6%, 4.8%, 5.0% or any value that meets the above range.

[0112] Exemplarily, the Young's modulus of the high modulus and high strength and toughness titanium-based composite material can be one of 130 GPa, 132 GPa, 134 GPa, 135 GPa, 136 GPa, 138 GPa, 140 GPa, 142 GPa, 144 GPa, 145 GPa, 146 GPa, 148 GPa, 150 GPa, 151 GPa, 153 GPa, and 155 GPa, or any value that satisfies the above range.

[0113] The present invention adopts functionalized borophene-graphene composite powder as raw material, utilizes wet mixing process to apply powder, and combines laser selective melting technology to prepare borophene-graphene reinforced titanium-based composite material.

[0114] First, the graphene and sodium borohydride are mixed evenly by in-situ thermal decomposition, and then heated and calcined, and a layer of borene is plated on the surface of the graphene to achieve the modification of the graphene. The calcined product is then placed in a 60% to 70% ethanol solution, and while removing the sodium element, oxygen-containing functional groups such as hydroxyl groups are plated on its surface by utilizing the electron-deficient characteristics of boron to achieve the functionalization of the borene-graphene powder. The composite powder is then filtered and dried in a vacuum drying oven at 50°C to 80°C to obtain a functionalized borene-graphene composite powder.

[0115] Finally, a certain amount of functionalized borophene-graphene composite powder was weighed according to the set enhancement ratio and dispersed in an ethanol solution, and ultrasonic dispersion and mechanical stirring were carried out for 30 min to 45 min. Subsequently, the composite powder slurry was poured into the titanium powder slurry, and ultrasonic dispersion and mechanical stirring were continued for 30 min to 45 min for dispersion. After the mixed slurry was filtered and dried, a uniformly coated borophene-graphene-titanium composite powder was obtained. Subsequently, combined with the selective laser melting technology, the borophene-graphene reinforced titanium matrix composite was prepared using the optimal process parameters screened in the previous work. During the processing and preparation, the borophene attached to the surface of graphene reacted with titanium to generate titanium boride whiskers, titanium boride nanoparticles, and titanium carbide nanoparticles. On the one hand, it played an insulating effect between graphene and the titanium matrix, reduced the reaction degree between graphene and titanium, increased the retention of graphene in the workpiece, and improved the overall modulus of the composite material by virtue of the excellent elastic modulus of graphene itself. On the other hand, titanium boride could play a pinning effect between the interfaces, improve the interfacial bonding degree between the titanium matrix, titanium carbide, and graphene, reduce the initiation and propagation of fine cracks during the stress process, and improve the ductility of the composite material.

[0116] Unless otherwise defined, the technical terms used in the following examples have the same meanings as commonly understood by those skilled in the art to which the present invention belongs. The experimental reagents used in the following examples are all conventional biochemical reagents unless otherwise specified; the raw materials, instruments, and equipment used in the following examples can all be obtained through market purchases or by existing methods; the dosages of the experimental reagents are the dosages of the reagents in conventional experimental operations unless otherwise specified; the experimental methods are all conventional methods unless otherwise specified.

[0117] Example 1

[0118] Preparation of functionalized borophene-graphene composite powder:

[0119] Throughout the process, under an argon atmosphere, weigh Figure 2 10 g of sodium borohydride as shown and Figure 15g of graphene as shown is placed in a mixing bottle and mixed evenly so that the mixed powder is in the form of a gray powder as a whole, avoiding the aggregation of too much black graphene or white sodium borohydride in the powder, and then pouring the mixed powder into a calcination boat. Adjust the heating program of the tubular furnace to carry out segmented heating and calcination. The heating rate of the first segment is set to 10℃ / min, heating to 490℃ and keeping warm for 2h; the heating rate of the second segment is 5℃ / min, heating to 550℃ and keeping warm for 0.5h; the heating rate of the third segment is 5℃ / min, heating to 600℃ and keeping warm for 0.5h. After the heating and calcination is completed, it is cooled with the furnace, and the whole process is under argon protection to avoid oxidation. After the calcination is completed, the product is taken out and placed in an ethanol solution to remove the sodium metal element in the product material, and oxygen-containing functional groups are plated on the surface of the boron olefin. After the treatment is completed, the composite powder slurry is filtered and dried at 60℃ for 3h to obtain a functionalized boron olefin-graphene composite powder, such as Figure 3 shown.

[0120] Preparation of borophene-graphene-titanium composite powder:

[0121] Based on the mass of borene-graphene-titanium composite powder, the weight percentage of functionalized borene-graphene composite powder is 0.5wt%, and the enhancement ratio of borene-graphene-titanium composite powder is recorded as 0.5wt%. According to the above ratio, 9.5g of functionalized borene-graphene composite powder and corresponding titanium powder are taken, and the two powders are placed in an ethanol solution independently, and each is independently subjected to ultrasonic vibration for 45min and mechanical stirring for 45min to make it dispersed evenly, to obtain functionalized borene-graphene composite powder slurry and titanium powder slurry. Subsequently, the functionalized borene-graphene composite powder slurry is mixed with the titanium powder slurry, treated with an ultrasonic vibrator for 40min, and mechanically stirred for 30min to uniformly adsorb graphene on the surface of the titanium powder. Subsequently, the mixed slurry is filtered and dried at 400°C for 6h to obtain a borene-graphene-titanium composite powder with an enhancement ratio of 0.5wt%.

[0122] The morphology of the boron olefin-graphene-titanium composite powder with a reinforcement ratio of 0.5 wt % prepared in Example 1 is as follows: Figure 4 As shown, its microstructure includes titanium powder and boron olefin-graphene composite powder adsorbed on its surface. It can also be seen from the powdering effect of the functionalized boron olefin-graphene composite powder with a weight percentage of 0.5wt%. Due to the low content of graphene powder, only a single layer / few layers of flaky graphene structure exist on the surface of part of the titanium powder, and the adhesion effect between the powders is good. The graphene sheets and titanium powder are closely combined with less gaps, showing a coated form. In addition, the graphene sheets are evenly distributed in the titanium powder, and there is basically no agglomeration between the graphene sheets, which has a good dispersion state.

[0123] Preparation of borophene-graphene reinforced titanium matrix composite:

[0124] The boronene-graphene-titanium composite powder is formed by selective laser melting to obtain a boronene-graphene reinforced titanium matrix composite, that is, a high modulus and high strength and toughness titanium matrix composite. Among them, the set process parameters are specifically: the powder spreading speed is 0.06 mm / s, the laser power is 280 W, the scanning speed is 2000 mm / s, and the scanning spacing is 0.12 mm.

[0125] Figure 5 The specific morphology of the boronene-graphene reinforced titanium matrix composite prepared by the LPBF process in Example 1 is shown. Under the condition that the reinforcement ratio is 0.5 wt%, the density of the boronene-graphene reinforced titanium matrix composite reaches more than 99%, the tensile strength reaches 1373 MPa, the elongation is 4.47%, and the Young's modulus reaches 134 GPa. The amount of graphene powder is less, mainly the titanium matrix as a whole, the grains are relatively fine, the interfacial bonding degree is good, and there are no obvious defects.

[0126] Example 2

[0127] Preparation of functionalized borophene-graphene composite powder:

[0128] Throughout in an argon environment, weigh Figure 2 20 g of sodium borohydride shown in Figure 1 10 g of graphene shown in Figure 3 and place them in a mixing bottle and mix evenly, so that the overall mixed powder presents a grayish-white powder particle appearance, avoiding the situation of more black graphene or white sodium borohydride aggregation in the powder. After mixing evenly, put the mixed powder into a firing boat. Adjust the heating program of the tube furnace for segmented heating and calcination. In the first stage, set the heating rate to 10 °C / min and heat to 490 °C and hold for 2 h; in the second stage, set the heating rate to 5 °C / min and heat to 550 °C and hold for 0.5 h; in the third stage, set the heating rate to 5 °C / min and heat to 600 °C and hold for 0.5 h. After heating and calcination, cool with the furnace, and the whole process is in an argon protection environment to avoid oxidation. Take out the sintered product and place it in an ethanol solution to remove the sodium metal simple substance in the product material and apply oxygen-containing functional groups on the surface of boronene. After the treatment is completed, filter the composite powder slurry and dry it at 60 °C for 3 h to obtain a functionalized boronene-graphene composite powder, as shown in

[0129] Preparation of borophene-graphene-titanium composite powder:

[0130] According to the enhancement ratio of the borophene-graphene-titanium composite powder being 1.5 wt%, 19 g of functionalized borophene-graphene composite powder and the corresponding titanium powder were weighed. The two powders were independently placed in an ethanol solution and independently dispersed evenly by ultrasonic vibration for 45 min and mechanical stirring for 45 min to obtain a functionalized borophene-graphene composite powder slurry and a titanium powder slurry. Subsequently, the functionalized borophene-graphene composite powder slurry and the titanium powder slurry were mixed and treated with an ultrasonic vibrator for 40 min and mechanical stirring for 30 min to make graphene uniformly adsorbed on the surface of the titanium powder. Subsequently, the mixed slurry was filtered and dried at 400 °C for 6 h to obtain a borophene-graphene-titanium composite powder with an enhancement ratio of 1.5 wt%.

[0131] The morphology of the borophene-graphene-titanium composite powder with an enhancement ratio of 1.5 wt% prepared in Example 2 is as Figure 6 shown. Its microstructure includes titanium powder and the borophene-graphene composite powder adsorbed on its surface. It can also be seen that when the content of the functionalized borophene-graphene composite powder increases to 1.5 wt%, the powdering effect of graphene has been significantly improved, and graphene sheets are attached to the surface of many titanium powders, and the powder still presents a single-layer flaky morphology. With the increase in the graphene content, the number of graphene sheets attached to the surface of the titanium powder increases significantly, and the content of large-size graphene also increases significantly.

[0132] Preparation of borophene-graphene reinforced titanium matrix composite:

[0133] The borophene-graphene-titanium composite powder was subjected to selective laser melting forming to obtain a borophene-graphene reinforced titanium matrix composite. Among them, the set process parameters are specifically: the powder spreading speed is 0.06 mm / s, the laser power is 280 W, the scanning speed is 2000 mm / s, and the scanning spacing is 0.12 mm.

[0134] Figure 7 Shows the specific morphology of the borophene-graphene reinforced titanium matrix composite prepared by the LPBF process in Example 2. Under the condition of an enhancement ratio of 1.5 wt%, the relative density of the borophene-graphene reinforced titanium matrix composite reaches more than 99%, the tensile strength reaches 1471 MPa, the elongation is 3.7%, and the Young's modulus reaches 151 GPa. Through microstructure characterization and analysis, it can be known that the graphene in the prepared borophene-graphene reinforced titanium matrix composite shows good dispersion characteristics, and its two-dimensional sheet structure remains intact in the matrix, and no significant macroscopic agglomeration phenomenon is observed. High-resolution microscopic imaging shows that the grain size in the material system is relatively fine, a transition interface layer of titanium carbide (TiC) with a certain size is formed between the graphene sheets and the titanium matrix, and it can be seen that there are in-situ generated titanium boride (TiB) nano-reinforcement phases in the matrix, and their distribution is similar to that of graphene, forming a three-dimensional interconnected network structure.

[0135] Example 3

[0136] Preparation of functionalized borophene-graphene composite powder:

[0137] The whole process was carried out under argon atmosphere. Figure 2 35 g of sodium borohydride and Figure 1 15g of graphene as shown is placed in a mixing bottle and mixed evenly so that the mixed powder presents an overall appearance of grayish white powder particles, avoiding the appearance of more black graphene or white sodium borohydride aggregation in the powder. After mixing evenly, the mixed powder is placed in a sintering boat. Adjust the heating program of the tubular furnace to perform segmented heating and calcination. The heating rate of the first segment is set to 10℃ / min, heating to 490℃ and keeping warm for 2h; the heating rate of the second segment is 5℃ / min, heating to 550℃ and keeping warm for 0.5h; the heating rate of the third segment is 5℃ / min, heating to 600℃ and keeping warm for 0.5h. After the heating and calcination is completed, it is cooled with the furnace. The whole process is under argon protection to avoid oxidation. The sintered product is taken out and placed in an ethanol solution to remove the sodium metal element in the product material, and oxygen-containing functional groups are plated on the surface of the boronene. After the treatment is completed, the composite powder slurry is filtered and dried at 60℃ for 3h to obtain a functionalized boronene-graphene composite powder, such as Figure 3 shown.

[0138] Preparation of borophene-graphene-titanium composite powder:

[0139] According to the enhancement ratio of borene-graphene-titanium composite powder of 3.0wt%, 19g of functionalized borene-graphene composite powder and corresponding titanium powder were weighed, and the two powders were placed in an ethanol solution independently, and ultrasonic vibration was used for 45min and mechanical stirring was used for 45min to make them dispersed evenly, and functionalized borene-graphene composite powder slurry and titanium powder slurry were obtained. Subsequently, the functionalized borene-graphene composite powder slurry and titanium powder slurry were mixed, treated with an ultrasonic vibrator for 40min, and mechanically stirred for 30min to make graphene uniformly adsorbed on the surface of titanium powder. Subsequently, the mixed slurry was filtered and dried at 400°C for 6h to obtain a borene-graphene-titanium composite powder with an enhancement ratio of 3.0wt%.

[0140] The morphology of the boron olefin-graphene-titanium composite powder with a reinforcement ratio of 3.0 wt% prepared in Example 3 is as follows: Figure 8As shown, its microstructure includes titanium powder and the borophene-graphene composite powder adsorbed on its surface. It can also be seen that when the content of the functionalized borophene-graphene composite powder increases to 3 wt%, the number of graphene sheets significantly increases, and more graphene sheets adhere to the surface of the titanium powder particles. Compared with the reinforcement ratios of 0.5 wt% and 1.5 wt%, when the reinforcement ratio is 3 wt%, there is a certain powder agglomeration phenomenon of graphene on the surface of the titanium powder, forming a relatively thick sheet aggregation layer. Although there is a certain agglomeration phenomenon between the graphene sheets at a content of 3.0 wt%, its dispersion degree still has a great advantage compared with the original graphene. Its agglomeration situation and sheet thickness are significantly reduced, and the powder coating situation and coating effect are also significantly improved.

[0141] For the crystal structure of graphene, by comparing and analyzing the size, morphology, and number of layers of the borophene-modified graphene and the original graphene, no obvious changes have occurred in the borophene-modified graphene. Its lateral size still remains in the range of 10 μm to 50 μm. And after being modified by borophene, the sheet thickness of the graphene is greatly reduced, and the number of sheets is significantly reduced, without causing significant lattice damage to the graphene.

[0142] Preparation of borophene-graphene reinforced titanium matrix composite:

[0143] The borophene-graphene-titanium composite powder is formed by selective laser melting to obtain a borophene-graphene reinforced titanium matrix composite. Among them, the specific process parameters are set as follows: the powder spreading speed is 0.06 mm / s, the laser power is 280 W, the scanning speed is 2000 mm / s, and the scanning spacing is 0.12 mm.

[0144] Figure 9 The specific morphology of the borophene-graphene reinforced titanium matrix composite prepared by the LPBF process in Example 3 is shown. Under the condition of a reinforcement ratio of 3.0 wt%, the relative density of the borophene-graphene reinforced titanium matrix composite reaches more than 99%, the tensile strength reaches 1347 MPa, the elongation is 2.47%, and the Young's modulus reaches 146 GPa.

[0145] See Figure 10As shown, compared with the borophene-graphene reinforced titanium matrix composites with two different enhancement ratios in Example 2 and Example 3, the borophene-graphene reinforced titanium matrix composite in Example 1 has lower modulus and tensile strength, but overall better plasticity. Compared with the borophene-graphene reinforced titanium matrix composite with an enhancement ratio of 1.5 wt%, the tensile strength, Young's modulus, and elongation of the borophene-graphene reinforced titanium matrix composite with an enhancement ratio of 3.0 wt% are all reduced. This is mainly because the content of graphene is relatively high, and partial agglomeration of graphene powder occurs again during the preparation process, resulting in the inability to exert the intrinsic properties of graphene. Moreover, excessive graphene content reacts with the titanium matrix to generate more brittle titanium carbide phase interfaces. During the subsequent stress application process, the modulus is reduced. At the same time, stress concentration is likely to occur at the agglomeration sites and interface bonding sites, the crack propagation is rapid, and the plasticity is reduced.

[0146] Comparative Example 1

[0147] Prepared according to the same process as Example 1 above, except that the graphene is not modified by borophene. Directly place pure graphene powder with a weight percentage of 0.5 wt% and the corresponding weight of titanium powder independently in an ethanol solution, and independently disperse them evenly by ultrasonic vibration for 30 min and mechanical stirring for 30 min to obtain a graphene powder slurry and a titanium powder slurry. Subsequently, mix the graphene powder slurry and the titanium powder slurry, and process them with an ultrasonic vibrator for 40 min and mechanical stirring for 30 min. Then filter the mixed slurry and dry it at 400 °C for 6 h to obtain a graphene-titanium composite powder with the same enhancement ratio of 0.5 wt% as in Example 1, see Figure 11 shown, for comparing the improvement of boronated graphene in powder coating.

[0148] Comparative Example 2

[0149] Prepared according to the same process as Example 2 above, except that the graphene is not modified by borophene. Directly place pure graphene powder with a weight percentage of 1.5 wt% and the corresponding weight of titanium powder independently in an ethanol solution, and independently disperse them evenly by ultrasonic vibration for 30 min and mechanical stirring for 30 min to obtain a graphene powder slurry and a titanium powder slurry. Subsequently, mix the graphene powder slurry and the titanium powder slurry, and process them with an ultrasonic vibrator for 40 min and mechanical stirring for 30 min. Then filter the mixed slurry and dry it at 400 °C for 6 h to obtain a graphene-titanium composite powder with the same enhancement ratio of 1.5 wt% as in Example 2, see Figure 12 shown, for comparing the improvement of boronated graphene in powder coating.

[0150] Comparative Example 3

[0151] Prepared by the same process as in Example 3 above, except that the graphene was not modified with borophene. Pure graphene powder with a weight percentage of 3.0 wt% and the corresponding weight of titanium powder were independently placed in an ethanol solution, and were independently dispersed evenly by ultrasonic vibration for 30 min and mechanical stirring for 30 min to obtain a graphene powder slurry and a titanium powder slurry. Subsequently, the graphene powder slurry and the titanium powder slurry were mixed and treated with an ultrasonic vibrator for 40 min and mechanical stirring for 30 min. Subsequently, the mixed slurry was filtered and dried at 400 °C for 6 h to obtain a graphene-titanium composite powder with the same enhancement ratio of 3.0 wt% as in Example 3, see Figure 13 as shown, for comparing the improvement of boronated graphene in powder coating.

[0152] Since pure graphene was used in Comparative Examples 1 to 3, the powder coating effect was not good. Compared with the modified borophene-graphene powder, the agglomeration effect was too large, resulting in large-area graphene agglomeration in the subsequent processing of titanium matrix composites, leading to problems such as excessive stress concentration, cracking, and extremely poor plasticity.

[0153] Comparative Example 4

[0154] In the prior art, titanium powders with different particle sizes were used as raw materials. Graphene was coated on the surface of large-particle-size titanium powder, and boron powder was coated on the surface of small-particle-size titanium powder. Then the two were mixed to obtain a graphene-boron heterostructure titanium-based mixed powder. The dispersion process was low-energy ball milling dispersion at 200 r / min for 4 h. Finally, it was prepared into a molded product by spark plasma sintering. The process parameters were a heating rate of 100 °C / min, a temperature of 900 °C to 1100 °C, a time of 6 min, and a pressure of 40 MPa to 60 MPa. Finally, by adjusting the proportion of graphene and boron, a tensile strength of 997 MPa, an elongation of 6.17%, and a Young's modulus of 127 GPa were prepared.

[0155] The present invention can indirectly increase oxygen-containing functional groups on the powder surface without destroying the lattice structure of graphene by first depositing borophene on the surface of graphene and performing functionalization treatment. This process avoids the damage effect of high-energy ball milling and chemical modification on graphene, effectively improves the dispersion ability of the powder in an aqueous solution, and enhances its dispersibility while maintaining the integrity of the graphene lattice. Secondly, compared with other processes, using the LPBF process with extremely high heating and cooling rates can further reduce the degree of interfacial reaction between graphene and the titanium matrix, retain the integrity of graphene, and at the same time refine the grain size and the size of the reinforcing particles, which is beneficial to constructing a nano-size configuration in the matrix. Based on the synergistic strengthening of the comprehensive mechanical properties of the titanium matrix composite by optimizing the powder and the configuration, the goal of high modulus, high strength, and high toughness performance is achieved.

[0156] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a high-modulus and high-strength and tough titanium matrix composite, characterized in that, The preparation method includes: Preparing a functionalized borophene-graphene composite powder from sodium borohydride and graphene as raw material powders; Using a wet mixing process to dissolve titanium powder and the functionalized borophene-graphene composite powder in an alcohol solvent, and subjecting the obtained mixed slurry to first filtration and first drying to obtain a borophene-graphene-titanium composite powder; Using the LPBF technology to perform selective laser melting forming on the borophene-graphene-titanium composite powder to prepare the high-modulus and high-strength and tough titanium matrix composite material.

2. The preparation method of the high modulus and high strength and toughness titanium matrix composite material according to claim 1, characterized in that, The process parameters of the selective laser melting forming include: the powder spreading speed is 0.04 mm / s to 0.08 mm / s, the laser power is 240 W to 300 W, the scanning speed is 1800 mm / s to 2000 mm / s, and the scanning spacing is 0.10 mm to 0.14 mm.

3. The preparation method of the high modulus and high strength and toughness titanium matrix composite material according to claim 1, characterized in that, The preparation of the functionalized borophene-graphene composite powder includes: Performing segmented heating and calcination on the mixed powder of the sodium borohydride and the graphene, and Placing the calcined product in an ethanol solution, and then subjecting it to second filtration and second drying to prepare the functionalized borophene-graphene composite powder.

4. The preparation method of the high-modulus and high-strength and tough titanium matrix composite material according to claim 3, wherein, The mass ratio of the graphene to the sodium borohydride is 1:(1 to 4); preferably 1:(2 to 4); Preferably, the second drying temperature is 60 °C to 80 °C, and the second drying time is 3 h to 5 h.

5. The preparation method of the high-modulus and high-strength and tough titanium matrix composite material according to claim 3, characterized in that, Three-stage heating and calcination is adopted, wherein the first-stage calcination temperature is 460 °C to 490 °C, and the calcination time is 2 h to 2.5 h; the second-stage calcination temperature is 530 °C to 550 °C, and the calcination time is 0.5 h to 1 h; the third-stage calcination temperature is 600 °C to 650 °C, and the calcination time is 0.5 h to 1 h.

6. The preparation method of the high-modulus and high-strength and tough titanium matrix composite material according to claim 5, wherein, The heating rate of the first-stage calcination is 10 °C / min to 15 °C / min; and / or, the heating rate of the second-stage calcination is 5 °C / min to 10 °C / min; and / or, the heating rate of the third-stage calcination is 5 °C / min to 10 °C / min.

7. The preparation method of the high-modulus and high-strength and tough titanium matrix composite material according to claim 3, characterized in that, Performing ultrasonic vibration and / or mechanical stirring on the mixed slurry before the first filtration; Preferably, the ultrasonic vibration time is 30 min to 60 min, and the mechanical stirring time is 30 min to 60 min.

8. The preparation method of the high-modulus and high-strength and tough titanium-based composite material according to claim 1, wherein, The first drying temperature is 400 °C to 500 °C, and the first drying time is 5 h to 7 h.

9. The preparation method of the high modulus and high strength and toughness titanium matrix composite material according to claim 1, characterized in that, Based on the mass of the borophene-graphene-titanium composite powder, the mass percentage of the functionalized borophene-graphene composite powder is 0.5 wt% to 3 wt%.

10. A high-modulus and high-strength and tough titanium-based composite material, characterized in that, The high-modulus and high-strength and tough titanium matrix composite material is prepared by the preparation method according to any one of claims 1 to 9; Preferably, the relative density of the high-modulus and high-strength and tough titanium matrix composite material is ≥99%, the tensile strength is 1300 MPa to 1500 MPa, the elongation is 2.0% to 5.0%, and the Young's modulus is 130 GPa to 155 GPa.

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