TiBw and TiCp synergistic reinforced double-base heterogeneous structure titanium matrix composite and its preparation method and application

Abstract

This invention discloses an in-situ self-generated TiBw and TiCp synergistically reinforced bi-matrix heterostructure titanium matrix composite material prepared by powder metallurgy, and its preparation method. This invention aims to solve the problems of "strength-plasticity mismatch" and insufficient dynamic impact energy absorption efficiency in traditional titanium alloys and their composites. The composite material uses pure Ti as the soft phase, TC4 as the hard phase, and B4C particles as the reinforcing precursor. It can be formed by low-energy ball milling, vacuum drying, rapid hot pressing sintering, and heat treatment, without subsequent rolling or forging. B4C reacts in-situ with the matrix to generate TiBw (TiBw) and TiCp (TiCp), constructing a discontinuous in-situ self-generated bi-scale TiBw and TiCp synergistically reinforced heterostructure at the soft-hard phase interface, achieving a significant synergistic effect of strengthening and toughening. The prepared composite material has a quasi-static tensile strength of 1085 MPa and a fracture strain of 16.3%; at 3000 s⁻¹, the tensile strength is 1085 MPa. ‑1 The dynamic compressive strength under strain rate reaches 1562 MPa, with a true strain of 27.8% and an energy absorption efficiency of 408 MJ / m³. This composite material achieves synergistic optimization of high strength, high plasticity, and high energy absorption through mechanisms such as twinned coordinated plasticity, multi-stage whisker fracture energy dissipation, and adiabatic shear band suppression. The invention features a simple process and low cost, making it suitable for the fabrication of lightweight, high-impact-resistant structural components for aerospace, armor protection, and other applications.

Description

Technical Field

[0001] This invention relates to the field of metal matrix composite material preparation technology, and more particularly to an in-situ self-generated TiBw and TiCp reinforced double-matrix (TC4+Ti) heterostructure titanium matrix composite material based on powder metallurgy, its preparation method, and its applications. This invention utilizes spark plasma sintering or rapid hot pressing sintering combined with heat treatment processes to construct an in-situ self-generated TiBw and TiCp reinforced double-matrix (TC4+Ti) heterostructure titanium matrix composite material with a multi-scale heterostructure design. It is particularly suitable for preparing lightweight structural materials that possess high strength, high plasticity, and excellent energy absorption efficiency under impact-resistant environments. This material can be widely used in aerospace, armor protection, automotive, and civilian equipment fields. Background Technology

[0002] Titanium alloys are a typical class of lightweight, high-strength structural materials, characterized by low density, high specific strength, excellent corrosion resistance, and high-temperature performance. They are widely used in engineering fields such as aerospace, energy equipment, and biomedicine. However, with the rapid growth in demand for larger, lighter, and more complex components, the mechanical properties and service stability of existing titanium alloys are still insufficient to meet the development requirements of high-end equipment.

[0003] Titanium-based composites are considered a new generation of high-performance structural materials due to their combination of high specific strength, good impact resistance, and low density. Existing research mainly focuses on improving strength by introducing external reinforcing phases (such as TiC, TiB, SiC, etc.) into the titanium matrix. However, this usually requires a high content (>10 wt%) of the reinforcing agent, and the interface between the reinforcing phase and the matrix is ​​often a single structure. This results in a significant decrease in plasticity (elongation is often less than 5%) while improving the material's strength, which severely limits its engineering applications.

[0004] Under the requirements of lightweight design, how to further improve the strength of titanium-based materials while maintaining high plasticity has become a major challenge in current materials design. Traditional strengthening strategies often result in a "strength-plasticity mismatch," mainly due to the following technical bottlenecks: 1. Inversion of strength and plasticity: When a single matrix is ​​combined with a reinforcement, the strengthening of the reinforcement leads to a significant reduction in plasticity, making it difficult for the material to balance strength and ductility. 2. Insufficient dynamic properties: Existing research on titanium-based composite materials mainly focuses on quasi-static mechanical properties, with limited application to high strain rates (>10). 3 s -1 The dynamic impact response and energy absorption mechanism under these conditions lack systematic research; 3. High process complexity: Traditional processes rely on post-processing such as rolling or forging to eliminate porosity and defects, which is complex, time-consuming and costly.

[0005] In recent years, the concept of heterogeneous structure design has been introduced into titanium alloy systems. By creating strain coordination and stress distribution between the soft and hard phases, a synergistic improvement in strength and plasticity can be achieved. Simultaneously, the in-situ reaction of B4C with the matrix can generate fine TiBw and TiCp particles, which helps strengthen the interface between the soft and hard phases and enhance load transfer. However, systematic research and effective design are still lacking regarding the multi-scale coupling strengthening mechanism of dual-matrix systems (such as TC4 / Ti) and B4C reinforcements under dynamic loading.

[0006] Therefore, how to introduce appropriately sized B4C reinforcements into a titanium matrix and achieve synergistic improvement in strength and plasticity through controllable interfacial reactions and heterogeneous structure design, while also taking into account excellent dynamic energy absorption performance, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0007] Given the limitations of existing titanium-based composite materials, such as the difficulty in achieving a balance between strength and plasticity, insufficient dynamic energy absorption, and complex and costly processes, this invention proposes a low-cost preparation method based on a roll-free powder metallurgy process, and constructs a titanium-based composite material with a heterogeneous structure. This process enables one-step forming, producing a novel dual-matrix (TC4+Ti) titanium-based composite material with TC4 titanium alloy (hard phase) and pure Ti (soft phase) as the dual matrix, and synergistic reinforcement of TiBw and TiCp through in-situ reaction of B4C. The material prepared by this invention significantly improves quasi-static tensile strength while achieving a synergistic effect of strength and plasticity, along with excellent dynamic energy absorption efficiency, breaking through the design bottleneck of traditional titanium-based composite materials where "strength and plasticity are difficult to achieve simultaneously."

[0008] The technical solution of this invention is:

[0009] 1. Composite material structures The composite material comprises a matrix and a reinforcement: (1) Matrix structure: It is composed of a soft-hard coupled double continuous network of TC4 titanium alloy (hard phase) and pure Ti (soft phase), and after in-situ reaction, it forms a discontinuous in-situ self-generated double-scale TiBw and TiCp synergistic reinforcement type α+β dual phase structure; (2) Formation of the reinforcing phase: The initial reinforcing precursor introduced is B4C, which generates TiBw and TiCp through in-situ reaction; (3) Interface structure: TiBw is distributed in three dimensions at the interface between the soft and hard matrix, while TiCp is distributed in a particle-dispersed manner. The two work together to construct a “whisker particle” coupling reinforcement unit that strengthens the interface bonding. Some TiBw and TiCp are further distributed in the crystal through diffusion mechanism to achieve a multi-level synergistic reinforcement effect between the interface and the crystal.

[0010] 2. Preparation method This invention also provides a method for preparing an in-situ self-generated TiBw and TiCp synergistically reinforced bi-molecular heterostructure titanium-based composite material, comprising the following steps: (1) Mixing powder and ball milling: Ti powder with similar particle size and mass fraction was mixed with TC4 titanium alloy powder in a certain proportion, and nano-sized B4C particles were added. The mixture was then ball-milled uniformly in anhydrous ethanol.

[0011] Among them, B4C is 0.2 wt% to 2 wt%, Ti is 35 wt% to 65 wt%, and TC4 is 35 wt% to 65 wt%.

[0012] Preferred particle sizes: TC4 powder 15–45 μm, B4C powder 50–200 nm.

[0013] Ball milling parameters: rotation speed 200–500 rpm, time 4–8 h, ball-to-material ratio 5–20:1, medium 300–500 mL of anhydrous ethanol. Two types of zirconia balls (3–5 mm and 1–3 mm in diameter, with a mass ratio of 2–5:1) were used as the milling medium.

[0014] (2) Vacuum drying: After ball milling, remove the grinding balls, place the slurry in a 500-1000 mL eggplant-shaped flask, and vacuum dry it at 60-85 °C for 0.5-2 h to remove ethanol and obtain a dry and uniform mixed powder.

[0015] (3) Hot pressing and sintering: The rapid hot pressing sintering (SPS) process was adopted, and sintering was carried out under vacuum conditions (vacuum degree <15 Pa).

[0016] Preferred parameters: heating rate 100-200 ℃ / min, sintering temperature 550-700 ℃, pressure 300-900 MPa, holding time 10-20 min, to obtain a circular preform with a diameter of 20-30 mm and a thickness of 5-15 mm.

[0017] (4) Heat treatment reaction: Heat treatment is performed using a vacuum atmosphere muffle furnace, atmosphere tube furnace, or pit furnace to promote the full in-situ reaction of B4C with the matrix to generate TiBw and TiCp. The specific steps are as follows: ① Load the furnace at room temperature and evacuate to <15 Pa; ② Refill with high-purity argon gas to a slightly positive pressure; ③ Increase the temperature to 700-800℃ at a rate of 5-10℃ / min and hold for 30-120 min; ④ After heat preservation, the mixture is slowly cooled to 200-300℃ at a rate of 5-8℃ / min for annealing, and finally cooled to room temperature in the furnace to obtain a heterostructure titanium-based composite material with TiBw / TiCp synergistic reinforcement. Beneficial effects

[0019] (1) This invention proposes a novel method for preparing TiBw and TiCp synergistically reinforced dual-matrix (TC4+Ti) heterostructure titanium matrix composites using roll-free powder metallurgy. Through low-energy ball milling, rapid hot-pressing sintering, and heat treatment, in-situ reactions of B4C are achieved at the soft-hard phase interface and within the grains, forming a multi-scale distribution structure of TiBw and TiCp. This constructs a discontinuous, in-situ, self-generated dual-scale TiBw and TiCp synergistically reinforced microstructure of a "TiBw-TiCp" three-dimensional reinforcement network. The material matrix exhibits an ultrafine α+β dual-phase structure, with Ti as the outer shell and TC4 as the core. TiBw acts as a bridge and pinning agent at the interface, while TiCp disperses and strengthens the grain boundaries. The synergistic effect of both achieves efficient load transfer and crack propagation suppression, significantly improving the overall strength and toughness of the material.

[0020] (2) In the composite material of the present invention, the Ti soft phase has a highly plastic single α-phase structure, and the TC4 hard phase maintains an α+β biphase equiaxed structure, forming a heterogeneous matrix system. During ball milling and sintering, the soft Ti phase undergoes plastic extrusion deformation in the vicinity of the high-strength TC4, forming a discontinuous in-situ self-generated dual-scale TiBw and TiCp synergistic reinforcement structure, in which TC4 acts as an anti-deformation core, and Ti forms a coordinated outer shell. This structure is macroscopically uniform but microscopically incompletely encapsulated, effectively promoting strain coordination and stress redistribution, enabling the hard phase to fully bear stress while the soft phase maintains its plastic deformation capacity.

[0021] (3) By combining the design of dual matrix heterostructure with in-situ reinforcement mechanism, this invention realizes a multi-level coupling system of "soft and hard matrix gradient + multi-scale reinforcement phase". By utilizing the complementary properties of matrix and the interface strengthening effect, the contradiction of "strength-plasticity" inversion in traditional single matrix composite materials is solved.

[0022] (4) This invention employs a roll-free powder metallurgy process, which simplifies the preparation process and reduces costs while significantly improving the quasi-static tensile strength and high strain rate (3000 s⁻¹) of the material. -1 The dynamic compression properties exhibit a coupling law of "strong plasticity balance and high energy absorption efficiency". The diffusion of Al and V elements at the heterogeneous interface (V substitution solid solution, Al diffusion restriction), dislocation pinning of the TiBw-TiCp reinforcing phase and the inhibition of adiabatic shear bands (ASB) work together to achieve a toughening effect, providing a new strategy for the structural optimization of titanium-based composite materials.

[0023] (5) Comprehensive mechanical property advantages: The tensile strength of this material reaches 1085 MPa and the fracture strain exceeds 15% under quasi-static tensile conditions. Under dynamic compression conditions with a strain rate of 3000 s⁻¹, the true stress reaches 1562 MPa and the true strain is 27.8%, with an energy absorption capacity as high as 408 MJ / m³. Compared with the control material at the same strain rate, the B4C-(TC4+Ti) composite material significantly improves strength and energy absorption performance while maintaining good plasticity: compared with B4C-Ti, its strength is increased by 48.8% and energy absorption is increased by 34%; compared with B4C-TC4, its plasticity is increased by 65% ​​and energy absorption is increased by 32.2%. Compared with the TiCp / TC4 reported in the literature... [1] and (TiBw&GNPs)-Ti [2] Ti-TiBw-TA15 [3] Compared to other titanium-based composite materials, the material of this invention achieves a superior balance in impact strength, plasticity, and energy absorption, far exceeding that of similar materials. Furthermore, the material of this invention also exhibits more significant comprehensive advantages in static mechanical properties. The B4C-(TC4+Ti) composite material (tensile strength 1085 MPa, fracture strain only 16.3%, energy absorption only 147.9 MJ / m³) demonstrates superior performance compared to other reinforced titanium-based composite materials reported in the literature, such as D24-GNP@TiB2-TC4 (tensile strength 1233 MPa, fracture strain only 3.8%, energy absorption 39.5 MJ / m³). [4] 0.05 wt%(NiTi2+TiC) / Ti [5] (Tensile strength 958 MPa, fracture strain only 17.6%, energy absorption only 17.2 MJ / m³), 0.1 wt% (NiTi2+TiC) / Ti [5] (Tensile strength 994 MPa, fracture strain only 10.5%, energy absorption 92.5 MJ / m³), S5.0-GNFs / Ti(HT) [6] (Tensile strength 732 MPa, fracture strain only 18.6%, energy absorption 135.8 MJ / m³) and GNPs / TC4 [7] (Tensile strength 1160 MPa, fracture strain only 12.8%, energy absorption 116.3 MJ / m³), compared to B4C-Ti tensile properties: strength increased by 48.8%, energy absorption increased by 34%; compared to B4C-TC4 tensile properties: plasticity increased by 65%, energy absorption increased by 32.2%.

[0024] In summary, the process route and material system proposed in this invention reduce manufacturing costs while taking into account high strength, high plasticity and excellent energy absorption characteristics, providing a new material solution for lightweight high ballistic structural components, armor protection and aerospace equipment. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the microstructure of the B4C reinforcement obtained in step (1) of the embodiment and its distribution in the mixed powder.

[0026] Figure 1 (a)~(c) are Figure 1 (d) shows enlarged views of different regions. Figure 1 (b1) to (b5) are the energy dispersive spectroscopy (EDS) analysis results of the reinforcement on the surface of spherical powder; Figure 1 (e1)~(e3) show the initial morphology and chemical composition identification results of the B4C reinforcer.

[0027] Figure 2 The image shows the initial microstructure (SEM image) of the in-situ self-generated TiBw and TiCp synergistically reinforced dual-matrix heterostructure titanium matrix composite material obtained in step (3) of the example.

[0028] Figure 3 The image shows the microstructure (SEM image) of the in-situ self-generated TiBw / TiCp reinforcing phase at the interface between the soft and hard phases in the composite material prepared in step (3) of the example.

[0029] Figure 4 The diffusion distribution of TC4 / Ti matrix elements in the in-situ self-generated TiBw and TiCp synergistically reinforced dual-matrix heterostructure titanium matrix composite material prepared in step (3) of the example is shown in the SEM-EDS figure.

[0030] Figure 5 The image shows the microstructure (SEM image) of the composite material after tensile deformation in step (3) of the embodiment.

[0031] Figure 6 The image shows the mixed dimple morphology (SEM image) of the quasi-static tensile fracture surface of the composite material in step (3) of the embodiment.

[0032] Figure 7 The internal stress distribution characteristics of the composite material static tensile fracture structure in step (3) of the embodiment are shown in the EBSD / KAM diagram.

[0033] Figure 8 The static-dynamic mechanical property curves of the composite material in step (3) of the example are shown, as well as the macroscopic deformation (bulging) morphology of the sample after dynamic compression.

[0034] Figure 9 The image shows the multi-level fracture morphology (SEM image) of TiBw after dynamic compression of the composite material in step (3) of the embodiment.

[0035] Figure 10 The image shows the extended morphology (SEM image) of the secondary thermal insulation shear band after dynamic compression of the composite material in step (3) of the embodiment.

[0036] Figure 11 The stress corrosion morphology (SEM image) of the region adjacent to the reinforcement after dynamic compression of the composite material in step (3) of the embodiment is shown.

[0037] Figure 12 The dislocation distribution characteristics of the secondary adiabatic shear band after dynamic compression of the composite material in step (3) of the embodiment are shown in the TEM image.

[0038] Figure 13 The pinning and strengthening effect of the in-situ self-generated reinforcement on dislocations after dynamic compression of the composite material in step (3) of the embodiment (TEM image).

[0039] Figure 14 The twin morphology, proportion, and dynamic recrystallization evolution characteristics (EBSD diagram) of the composite material after dynamic compression in step (3) of the embodiment are shown. Detailed Implementation

[0040] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the technical solutions of this invention are further described below in conjunction with specific embodiments. It should be noted that these embodiments are only used to illustrate the technical principles of this invention and do not constitute a limitation on the scope of protection of this invention. Based on the content of this invention, equivalent substitutions or modifications made by those skilled in the art without creative effort should be considered to fall within the scope of protection of this invention. It should be noted that, unless otherwise specified, the experimental methods described in the following embodiments are conventional methods, and the reagents and materials, unless otherwise specified, can be obtained commercially.

[0041] Example 1 This embodiment provides a TiBw / TiCp in-situ self-generated synergistic (TC4+Ti) heterostructure titanium-based composite material prepared by powder metallurgy. The specific steps are as follows: (1) Mixing powder and ball milling B4C, Ti, and TC4 titanium alloy powders were ball-milled in anhydrous ethanol to obtain a uniformly dispersed slurry. After removing the milling media, the mixture was vacuum-dried by rotary evaporation to obtain a mixed powder. The powder composition is as follows (based on 100% total mass): Nano B4C content is 1 wt%; The Ti powder mass fraction was 49.5 wt%; The mass fraction of TC4 titanium alloy powder is 49.5 wt%.

[0042] The process parameters are as follows: 500 mL of anhydrous ethanol was used. The ball mill speed is 250 r / min; Ball milling time: 6 hours; The ratio of balls to feed is 10:1. The grinding ball consists of two sizes of zirconia balls, with the larger ball having a diameter of 5 mm and the smaller ball having a diameter of 3 mm, and the mass ratio of the larger ball to the smaller ball being 5:1. The grinding jar is 20 cm in diameter and 20 cm in height, and is made of nylon.

[0043] Rotary drying process: After removing the grinding balls, the slurry was placed in a 1000 mL eggplant flask and vacuum dried at 75 °C for 2 h to completely remove the ethanol, resulting in a dried mixed powder.

[0044] (2) Rapid hot pressing sintering The resulting mixed powder was formed and densified in a mold using a rapid hot pressing sintering method.

[0045] The preferred process parameters are as follows: Vacuum degree 15 Pa; Heating rate: 100 ℃ / min; Sintering temperature: 650 ℃; Sintering pressure 300 MPa; Keep warm for 20 minutes.

[0046] A dense preform with a thickness of 10 mm and a diameter of 25 mm was obtained.

[0047] (3) Heat treatment and in-situ reaction Precise heat treatment of the sintered green body is carried out in a vacuum atmosphere muffle furnace or a high temperature atmosphere furnace to promote the in-situ reaction of B4C with the matrix to generate TiBw and TiCp.

[0048] The heat treatment operating procedures are as follows: ① Place the sample in a vacuum atmosphere furnace and load it into the furnace at room temperature; ② Evacuate to 15 Pa; ③ Refill with high-purity argon gas to a slightly positive pressure; ④ Increase the temperature to 750℃ at a rate of 5℃ / min; ⑤ Hold at the target temperature for 90 min to ensure that B4C reacts fully with the matrix; ⑥ Cool slowly to 200℃ at a rate of 8℃ / min, then air cool or cool with the furnace; ⑦ Cool to room temperature to obtain TiBw-TiCp in-situ self-generated synergistic reinforcement (TC4+Ti) heterostructure titanium matrix composite material.

[0049] Raw materials and equipment TC4 titanium alloy powder and Ti powder were purchased from Beijing Zhonghang Mait Powder Metallurgy Co., Ltd., with an average particle size of approximately 38 μm; nano B4C was purchased from Xianfeng Nanomaterials Co., Ltd., with a purity of 98.1% and a particle size of 500 nm; the rapid hot pressing sintering system was model FHP858 (Suzhou Hateng Technology Co., Ltd.).

[0050] Testing and Characterization Methods 1. Mechanical property testing: Quasi-static tensile and dynamic compression tests were conducted using a Zwick Z2.5 TH electronic universal testing machine (Zwick Roell, Germany) equipped with a Laser Xtens laser extensometer.

[0051] 2. Microscopic tissue characterization: SEM testing instrument: JEOL JSM7200F field emission scanning electron microscope; TEM testing instrument: FEI Tecnai G2 F20 transmission electron microscope; EBSD analysis is used to observe grain orientation and stress distribution.

[0052] Experimental Results and Analysis 1. Morphology of mixed powders: Field emission scanning electron microscopy results ( Figure 1 The results show that the Ti and TC4 powders are spherical with smooth surfaces, and the nano-sized B4C particles are uniformly attached to the surface of the TC4 spheres, exhibiting good dispersibility.

[0053] 2. Initial microstructure of composite materials: such as Figure 2 – Figure 4 As shown, the matrix structure after sintering is mainly composed of α and β phases, with tight interfacial bonding, no obvious pores, and good density. The in-situ generated TiBw and TiCp are diffusely distributed inside and outside the soft and hard phase interface, and some exhibit a "sea urchin" structure, which is beneficial for three-dimensional load transfer and interfacial bonding strengthening.

[0054] 3. Interface and fracture characteristics: tensile fracture ( Figure 5 – Figure 7 The results show that the soft and hard phase interfaces are tightly bonded, and the reinforcement exhibits both pull-out and fracture morphologies. The fracture surface displays a multi-level dimple structure, indicating that the composite material possesses excellent ductility and energy absorption capacity.

[0055] 4. Mechanical property results: such as Figure 8As shown, the quasi-static tensile strength of the composite material is 1085 MPa, the yield strength is 968 MPa, and the fracture strain is 16.3%; at a strain rate of 3000 s⁻¹, the composite material exhibits the following characteristics: -1 Under these conditions, the dynamic compressive true stress is 1562 MPa, the true strain is 27.8%, and the energy absorption efficiency reaches 408 MJ / m. 3 No shearing failure was observed.

[0056] 5. Dynamic deformation mechanism: SEM and TEM observation results ( Figure 9 – Figure 13 This indicates that TiBw undergoes multi-stage fracture, with TiCp exhibiting a diffuse distribution that acts as a pinning and load transfer mechanism for dislocations; a large number of twins and dynamic recrystallization structures are formed within the soft Ti region. Figure 14 This helps to coordinate plastic deformation and stress distribution, significantly improving dynamic impact resistance.

[0057] Example 2 This embodiment provides a TiBw / TiCp in-situ self-generated synergistic (TC4+Ti) heterostructure titanium-based composite material prepared by powder metallurgy. The specific steps are as follows: (1) Mixing powder and ball milling B4C, Ti, and TC4 titanium alloy powders were ball-milled in anhydrous ethanol to obtain a uniformly dispersed slurry. After removing the milling media, the mixture was vacuum-dried by rotary evaporation to obtain a mixed powder. The powder composition is as follows (based on 100% total mass): The content of nano-B4C is 2 wt%; The Ti powder mass fraction was 49 wt%; The mass fraction of TC4 titanium alloy powder is 49 wt%.

[0058] The process parameters are as follows: 500 mL of anhydrous ethanol was used. The ball mill speed is 250 r / min; Ball milling time: 6 hours; The ratio of balls to feed is 10:1. The grinding ball consists of two sizes of zirconia balls, with the larger ball having a diameter of 5 mm and the smaller ball having a diameter of 3 mm, and the mass ratio of the larger ball to the smaller ball being 5:1. The grinding jar is 20 cm in diameter and 20 cm in height, and is made of nylon.

[0059] Rotary drying process: After removing the grinding balls, the slurry was placed in a 1000 mL eggplant flask and vacuum dried at 75 °C for 2 h to completely remove the ethanol, resulting in a dried mixed powder.

[0060] (2) Rapid hot pressing sintering The resulting mixed powder was formed and densified in a mold using a rapid hot pressing sintering method.

[0061] The preferred process parameters are as follows: Vacuum degree 10 Pa; Heating rate: 100 ℃ / min; Sintering temperature: 650 ℃; Sintering pressure 300 MPa; Keep warm for 20 minutes.

[0062] A dense preform with a thickness of 10 mm and a diameter of 25 mm was obtained.

[0063] (3) Heat treatment and in-situ reaction Precise heat treatment of the sintered green body is carried out in a vacuum atmosphere muffle furnace or a high temperature atmosphere furnace to promote the in-situ reaction of B4C with the matrix to generate TiBw and TiCp.

[0064] The heat treatment operating procedures are as follows: ① Place the sample in a vacuum atmosphere furnace and load it into the furnace at room temperature; ② Evacuate to 10 Pa; ③ Refill with high-purity argon gas to a slightly positive pressure; ④ Increase the temperature to 750℃ at a rate of 5℃ / min; ⑤ Hold at the target temperature for 90 min to ensure that B4C reacts fully with the matrix; ⑥ Cool slowly to 200℃ at a rate of 8℃ / min, then air cool or cool with the furnace; ⑦ Cool to room temperature to obtain TiBw / TiCp in-situ self-generated synergistic reinforcement (TC4+Ti) heterostructure titanium matrix composite material.

[0065] Raw materials and equipment TC4 titanium alloy powder and Ti powder were purchased from Beijing Zhonghang Mait Powder Metallurgy Co., Ltd., with an average particle size of approximately 38 μm; nano B4C was purchased from Xianfeng Nanomaterials Co., Ltd., with a purity of 98.1% and a particle size of 500 nm; the rapid hot pressing sintering system was model FHP858 (Suzhou Hateng Technology Co., Ltd.).

[0066] Testing and Characterization Methods Mechanical property testing: Quasi-static tensile and dynamic compression tests were conducted using a Zwick Z2.5 TH electronic universal testing machine (Zwick Roell, Germany) equipped with a Laser Xtens laser extensometer.

[0067] Mechanical property results The composite material has a quasi-static tensile strength of 1235 MPa, a yield strength of 1128 MPa, and a fracture strain of 13.8%; at a strain rate of 3000 s⁻¹... -1 Under these conditions, the dynamic compressive true stress is 1722 MPa, the true strain is 23.8%, and the energy absorption efficiency reaches 459 MJ / m. 3 .

[0068] Example 3 This embodiment provides a TiBw / TiCp in-situ self-generated synergistic (TC4+Ti) heterostructure titanium-based composite material prepared by powder metallurgy. The specific steps are as follows: (1) Mixing powder and ball milling B4C, Ti, and TC4 titanium alloy powders were ball-milled in anhydrous ethanol to obtain a uniformly dispersed slurry. After removing the milling media, the mixture was vacuum-dried by rotary evaporation to obtain a mixed powder. The powder composition is as follows (based on 100% total mass): The content of nano-B4C is 0.5 wt%; The Ti powder mass fraction was 49.5 wt%; The mass fraction of TC4 titanium alloy powder is 49.5 wt%.

[0069] The process parameters are as follows: 500 mL of anhydrous ethanol was used. The ball mill speed is 250 r / min; Ball milling time: 6 hours; The ratio of balls to feed is 10:1. The grinding ball consists of two sizes of zirconia balls, with the larger ball having a diameter of 5 mm and the smaller ball having a diameter of 3 mm, and the mass ratio of the larger ball to the smaller ball being 5:1. The grinding jar is 20 cm in diameter and 20 cm in height, and is made of nylon.

[0070] Rotary drying process: After removing the grinding balls, the slurry was placed in a 1000 mL eggplant flask and vacuum dried at 75 °C for 2 h to completely remove the ethanol, resulting in a dried mixed powder.

[0071] (2) Rapid hot pressing sintering The resulting mixed powder was formed and densified in a mold using a rapid hot pressing sintering method.

[0072] The preferred process parameters are as follows: Vacuum degree 10 Pa; Heating rate: 100 ℃ / min; Sintering temperature: 600 ℃; Sintering pressure 300 MPa; Keep warm for 20 minutes.

[0073] A dense preform with a thickness of 10 mm and a diameter of 25 mm was obtained.

[0074] (3) Heat treatment and in-situ reaction Precise heat treatment of the sintered green body is carried out in a vacuum atmosphere muffle furnace or a high temperature atmosphere furnace to promote the in-situ reaction of B4C with the matrix to generate TiBw and TiCp.

[0075] The heat treatment operating procedures are as follows: ① Place the sample in a vacuum atmosphere furnace and load it into the furnace at room temperature; ② Evacuate to 10 Pa; ③ Refill with high-purity argon gas to a slightly positive pressure; ④ Increase the temperature to 800℃ at a rate of 5℃ / min; ⑤ Hold at the target temperature for 120 min to ensure that B4C reacts fully with the matrix; ⑥ Cool slowly to 200℃ at a rate of 8℃ / min, then air cool or cool with the furnace; ⑦ Cool to room temperature to obtain TiBw / TiCp in-situ self-generated synergistic reinforcement (TC4+Ti) heterostructure titanium matrix composite material.

[0076] Mechanical property results The composite material has a quasi-static tensile strength of 1081 MPa, a yield strength of 936 MPa, and a fracture strain of 19.8%; at a strain rate of 3000 s⁻¹... -1 Under these conditions, the dynamic compressive true stress is 1602 MPa, the true strain is 31.8%, and the energy absorption efficiency reaches 426 MJ / m. 3 .

[0077] Example 4 This embodiment provides a TiBw / TiCp in-situ self-generated synergistic (TC4+Ti) heterostructure titanium-based composite material prepared by powder metallurgy. The specific steps are as follows: (1) Mixing powder and ball milling B4C, Ti, and TC4 titanium alloy powders were ball-milled in anhydrous ethanol to obtain a uniformly dispersed slurry. After removing the milling media, the mixture was vacuum-dried by rotary evaporation to obtain a mixed powder. The powder composition is as follows (based on 100% total mass): The content of nano-B4C is 1.5 wt%; The Ti powder mass fraction was 49.25 wt%. The mass fraction of TC4 titanium alloy powder is 49.25 wt%.

[0078] The process parameters are as follows: 500 mL of anhydrous ethanol was used. The ball mill speed is 250 r / min; Ball milling time: 6 hours; The ratio of balls to feed is 10:1. The grinding ball consists of two sizes of zirconia balls, with the larger ball having a diameter of 5 mm and the smaller ball having a diameter of 3 mm, and the mass ratio of the larger ball to the smaller ball being 5:1. The grinding jar is 20 cm in diameter and 20 cm in height, and is made of nylon.

[0079] Rotary drying process: After removing the grinding balls, the slurry was placed in a 1000 mL eggplant flask and vacuum dried at 75 °C for 2 h to completely remove the ethanol, resulting in a dried mixed powder.

[0080] (2) Rapid hot pressing sintering The resulting mixed powder was formed and densified in a mold using a rapid hot pressing sintering method.

[0081] The preferred process parameters are as follows: Vacuum degree 10 Pa; Heating rate: 100 ℃ / min; Sintering temperature: 600 ℃; Sintering pressure 300 MPa; Keep warm for 20 minutes.

[0082] A dense preform with a thickness of 10 mm and a diameter of 25 mm was obtained.

[0083] (3) Heat treatment and in-situ reaction Precise heat treatment of the sintered green body is carried out in a vacuum atmosphere muffle furnace or a high temperature atmosphere furnace to promote the in-situ reaction of B4C with the matrix to generate TiBw and TiCp.

[0084] The heat treatment operating procedures are as follows: ① Place the sample in a vacuum atmosphere furnace and load it into the furnace at room temperature; ② Evacuate to 10 Pa; ③ Refill with high-purity argon gas to a slightly positive pressure; ④ Increase the temperature to 900℃ at a rate of 5℃ / min; ⑤ Hold at the target temperature for 90 min to ensure that B4C reacts fully with the matrix; ⑥ Cool slowly to 200℃ at a rate of 8℃ / min, then air cool or cool with the furnace; ⑦ Cool to room temperature to obtain TiBw / TiCp in-situ self-generated synergistic reinforcement (TC4+Ti) heterostructure titanium matrix composite material.

[0085] Mechanical property results The composite material has a quasi-static tensile strength of 1381 MPa, a yield strength of 1182 MPa, and a fracture strain of 7.8%; at a strain rate of 3000 s⁻¹... -1 Under these conditions, the dynamic compressive true stress is 1782 MPa, the true strain is 17.2%, and the energy absorption efficiency reaches 338 MJ / m. 3 .

[0086] Example 5 This embodiment provides a TiBw / TiCp in-situ self-generated synergistic (TC4+Ti) heterostructure titanium-based composite material prepared by powder metallurgy. The specific steps are as follows: (1) Mixing powder and ball milling B4C, Ti, and TC4 titanium alloy powders were ball-milled in anhydrous ethanol to obtain a uniformly dispersed slurry. After removing the milling media, the mixture was vacuum-dried by rotary evaporation to obtain a mixed powder. The powder composition is as follows (based on 100% total mass): The content of nano-B4C is 0.2 wt%; The Ti powder mass fraction was 49.9 wt%; The mass fraction of TC4 titanium alloy powder is 49.9 wt%.

[0087] The process parameters are as follows: 500 mL of anhydrous ethanol was used. The ball mill speed is 250 r / min; Ball milling time: 6 hours; The ratio of balls to feed is 10:1. The grinding ball consists of two sizes of zirconia balls, with the larger ball having a diameter of 5 mm and the smaller ball having a diameter of 3 mm, and the mass ratio of the larger ball to the smaller ball being 5:1. The grinding jar is 20 cm in diameter and 20 cm in height, and is made of nylon.

[0088] Rotary drying process: After removing the grinding balls, the slurry was placed in a 1000 mL eggplant flask and vacuum dried at 75 °C for 2 h to completely remove the ethanol, resulting in a dried mixed powder.

[0089] (2) Rapid hot pressing sintering The resulting mixed powder was formed and densified in a mold using a rapid hot pressing sintering method.

[0090] The preferred process parameters are as follows: Vacuum degree 10 Pa; Heating rate: 100 ℃ / min; Sintering temperature: 600 ℃; Sintering pressure 300 MPa; Keep warm for 20 minutes.

[0091] A dense preform with a thickness of 10 mm and a diameter of 25 mm was obtained.

[0092] (3) Heat treatment and in-situ reaction Precise heat treatment of the sintered green body is carried out in a vacuum atmosphere muffle furnace or a high temperature atmosphere furnace to promote the in-situ reaction of B4C with the matrix to generate TiBw and TiCp.

[0093] The heat treatment operating procedures are as follows: ① Place the sample in a vacuum atmosphere furnace and load it into the furnace at room temperature; ② Evacuate to <15 Pa; ③ Refill with high-purity argon gas to a slightly positive pressure; ④ Increase the temperature to 900℃ at a rate of 5℃ / min; ⑤ Hold at the target temperature for 90 min to ensure that B4C reacts fully with the matrix; ⑥ Cool slowly to 200℃ at a rate of 8℃ / min, then air cool or cool with the furnace; ⑦ Cool to room temperature to obtain TiBw / TiCp in-situ self-generated synergistic reinforcement (TC4+Ti) heterostructure titanium matrix composite material.

[0094] Mechanical property results The composite material has a quasi-static tensile strength of 1091 MPa, a yield strength of 893 MPa, and a fracture strain of 22.5%; at a strain rate of 3000 s⁻¹... -1 Under these conditions, the dynamic compressive true stress is 1504 MPa, the true strain is 24.2%, and the energy absorption efficiency reaches 362.8 MJ / m. 3 .

[0095] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

[0096] References [1] Hao Y, Liu J, Li J, et al. Rapid preparation of TiC reinforcedTi6Al4V based composites by carburizing method through spark plasma sinteringtechnique[J]. Materials&Design (1980-2015), 2015, 65: 94-97. [2] Liu L, Li Y, Zhang H, et al. Breaking through the dynamicstrength-ductility trade-off in TiB reinforced Ti composites by incorporationof graphene nanoplatelets[J / OL]. Composites Part B: Engineering, 2022, 230:109499. DOI: 10.1016 / j.compositesb.2021.109499. [3] Wang S, Sun F, Liu W, et al. Dynamic compression behavior ofmultilayered titanium matrix composites[J / OL]. Materials Characterization,2023. DOI: 10.1016 / j.matchar.2023.112698. [4] Wang H, Zhang H M, Cheng X W, et al. Effect of ball milling timeon microstructure and mechanical properties of graphene nanoplates and TiBwreinforced Ti–6Al–4V alloy composites[J / OL]. Materials Science andEngineering: A, 2022. DOI: 10.1016 / j.msea.2022.144240. [5] Ge Y, Zhang H, Cheng X, et al. Achieving high performance in(NiTi2 +TiC) / Ti composites with network architecture via reaction interfacedesign[J / OL]. Journal of Alloys and Compounds, 2022. DOI: 10.1016 / j.jallcom.2022.166230. [6] X.N. Mu, H.M. Zhang, P.W. Chen, et al. Achieving well-balancedstrength and ductility in GNFs / Ti composite via laminated architecture design[J / OL]. Carbon, 2021. DOI: 10.1016 / j.carbon.2021.11.049. [7] Duan H Q, Zhang H M, Cheng X W, et al. Enhanced strength andtoughness in TC4-(GNPs / TC4) composites via heterogeneous multi-scalelamination design[J / OL]. Materials Characterization, 2024. DOI: 10.1016 / j.matchar.2024.114184.

Claims

1. A synergistically reinforced in-situ self-generated TiBw and TiCp dual-matrix heterostructure titanium-based composite material, characterized in that: It includes a dual matrix structure, a reinforcement, and a microstructure, wherein the dual matrix structure uses pure Ti as a soft phase matrix and TC4 titanium alloy as a hard phase matrix, and the two are discontinuously distributed in three-dimensional space and form a gradient heterogeneous interface. The reinforcement uses B4C particles as a precursor to generate TiBw and TiCp through in-situ reaction, wherein the aspect ratio of TiBw is not less than 5:1 and the particle size of TiCp is greater than 50 nm. In the microstructure, the soft phase Ti encapsulates the hard phase TC4, and together with the in-situ self-generated dual-scale TiBw and TiCp reinforcements, they form a synergistic discontinuous multi-scale heterostructure. The reinforcement is distributed in the interface region between the soft phase and the hard phase and forms a whisker-particle synergistic reinforcement unit.

2. The composite material according to claim 1, characterized in that: The B4C particles have a particle size of 200 nm to 10 μm and a purity of not less than 99.9%, and the chemical equation for their in-situ reaction with the matrix is ​​B4C + 5Ti → 4TiB + TiC.

3. The composite material according to claim 1, characterized in that: In the discontinuous in-situ self-generated dual-scale TiBw and TiCp synergistic enhancement structure, the β grain size of the hard phase TC4 is 500 nm to 5 μm, and the α phase grain size of the soft phase Ti is 2 to 20 μm, thus forming a cross-scale heterostructure.

4. A method for preparing the composite material according to any one of claims 1 to 3, characterized in that: The process includes steps such as ball milling, vacuum drying, hot pressing sintering, solid-state reaction, and cooling forming. In the ball milling step, Ti powder and TC4 titanium alloy powder are mixed at a mass ratio of 1:

1. Add 0.2–2 wt% B4C particles, use anhydrous ethanol as a medium and add zirconia balls, with a ball-to-material ratio of 5:1–20:1, and ball mill at 200–400 rpm for 4–24 h; remove ethanol in the vacuum drying step to obtain a mixed powder; The hot pressing sintering step is carried out under vacuum conditions not exceeding 1×10⁻² Pa, temperature of 500~800 ℃, and pressure of 300~900MPa for 5~20 min to obtain sintered samples; the solid-state reaction step is carried out at 600~900 ℃ for 30~120 min to allow B4C to react in situ with the matrix to generate TiBw and TiCp; The cooling and molding step involves cooling to room temperature at a rate of 5–15 °C / min to obtain the heterostructured titanium-based composite material.

5. The preparation method according to claim 4, characterized in that: During the ball milling process, B4C particles are uniformly dispersed in Ti powder and TC4 titanium alloy powder.

6. The preparation method according to claim 4, characterized in that: The hot pressing sintering is carried out in a vacuum environment with a vacuum degree of 1 to 20 Pa, a sintering pressure of 300 to 900 MPa, and a holding time of not less than 5 min.

7. The preparation method according to claim 4, characterized in that: During the solid-phase reaction, Al and V elements do not diffuse between the soft phase Ti and the hard phase TC4, thus forming a heterogeneous interface with an elemental gradient distribution at the interface between the two.

8. The application of the composite material according to any one of claims 1 to 3 in the field of impact protection, characterized in that: The composite material is used to prepare energy-absorbing structures such as armor plates, engine impact-resistant components, or anti-collision structures for new energy vehicles.

9. The application according to claim 8, characterized in that: The composite material exhibits a dynamic compressive energy absorption efficiency of no less than 400 MJ / m³ under strain rates of 2000 s⁻¹ to 4000 s⁻¹, and its fracture surface displays gradient dimple characteristics, wherein the dimples in the soft phase region are larger and sparsely distributed, while the dimples in the hard phase region are smaller and densely distributed.

10. The composite material according to claim 1, characterized in that: Its microstructure contains 10-30% by volume deformed twins and paired adiabatic shear bands, the width of which is no more than 5 μm. TiBw enhances the interfacial bonding strength through the pinning effect, and TiCp is enriched at the whisker intersections.

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