Multistage three-dimensional nano layered titanium alloy and preparation method thereof

Abstract

The invention belongs to the field of alloy material science, and discloses a multistage three-dimensional nanometer layered titanium alloy and a preparation method thereof. The multistage three-dimensional nanometer layered titanium alloy is constructed by combining the steps of remolding deformation, heat treatment, second-phase particle introduction, retreatment and the like. The introduction of the multi-stage three-dimensional nano layered structure can significantly improve the performance of the material. For example, high strength and high toughness can be achieved at the same time through the synergistic effect of the multi-stage structure.

Description

Technical Field

[0001] The invention belongs to the field of alloy material science, and specifically relates to a multi-level three-dimensional nano-layered titanium alloy and a preparation method thereof. Background Art

[0002] With the rapid development of modern industry and high-end manufacturing, titanium alloy has become one of the most concerned structural materials due to its high specific strength, excellent corrosion resistance and good biocompatibility. Titanium alloys have been widely used in aerospace, marine engineering and biomedical fields, especially in the context of increasing requirements for lightweight and high performance. However, traditional titanium alloys still have some bottlenecks in performance, such as low fatigue performance, difficulty in balancing strength and toughness, and limitations in surface performance. The initiation and propagation of fatigue cracks are important factors limiting the service life of titanium alloys, and how to maintain good toughness while improving strength is the key challenge facing current material design. In addition, the corrosion resistance and wear resistance of titanium alloys in special environments (such as high salt spray and strong wear) still need to be further optimized. Therefore, researchers have begun to focus on the regulation of material microstructure to achieve an all-round improvement in the performance of titanium alloys. In recent years, the development of nanostructured materials has provided a new idea for improving the performance of titanium alloys, among which multi-level three-dimensional nanostructures have become a hot topic of research due to their synergistic strengthening effect at multiple scales.

[0003] The multi-level three-dimensional nano-layered structure is formed by constructing nano-scale grains, periodically superimposed nano-layered structures, and uniformly distributed second phase particles in the material, thereby forming a multi-level structure from micro to nano scale. Studies have shown that the nano-layered structure can significantly improve the strength of the material, while effectively inhibiting crack propagation through interface effects, and improving toughness and fatigue resistance. Summary of the invention

[0004] The present invention combines the steps of reshaping, heat treatment, second phase introduction and reprocessing to construct a multi-level three-dimensional nano-layered titanium alloy, which can meet the demand for high-performance materials in harsh environments and has important scientific significance and industrial value.

[0005] The main purpose of the present invention is to provide a method for preparing a multi-level three-dimensional nano-layered titanium alloy, comprising the following steps:

[0006] (1) Preparation of titanium-based alloy billets: The titanium-based alloy billets are prepared by vacuum melting, plasma rotating electrode method PREP or powder metallurgy technology to ensure that the composition is uniform and the impurity content is less than 0.2wt%;

[0007] (2) Reshaping deformation: The titanium-based alloy billet is plastically deformed by cumulative rolling ARB or high pressure torsion HPT technology, with a total deformation of ≥ 90%, so that the matrix grains are refined to the nanoscale and a preliminary layered structure is formed;

[0008] (3) Heat treatment: heat treatment at 300-800°C for 1 h to form a stable nano-layered structure;

[0009] (4) Introduction of second phase particles: TiC, TiB 2 , TiN particles or other intermetallic compounds are evenly distributed in the titanium alloy matrix; TiC, TiB 2 , the mass of TiN particles or other intermetallic compounds accounts for 1%-10% of the mass of the titanium alloy;

[0010] (5) Reprocessing: The product of step (4) is heat-treated again at 300-800° C. for 30-60 min to form a multi-level three-dimensional nano-layered titanium alloy.

[0011] In step (2), the specific steps of cumulative rolling ARB include:

[0012] a) The rolling reduction ratio of each pass is 50%-80%;

[0013] b) The rolling temperature is controlled at 200-400°C to avoid excessive hardening of the material;

[0014] c) Intermediate annealing is performed between passes at 400°C for 20 minutes to maintain the ductility of the material.

[0015] In step (2), the specific steps of high pressure torsion HPT include:

[0016] a) Torsional pressure ≥5GPa, number of revolutions ≥10 turns;

[0017] b) controlled cooling at 100 °C to suppress dynamic recrystallization and ensure the integrity of the lamellar structure;

[0018] c) Combined with hydrogenation treatment, the hydrogen embrittlement induction method is used to further refine the grains.

[0019] In step (4), the specific conditions of the CVD process are:

[0020] a) The reaction temperature is 800-1000°C;

[0021] b) The particle deposition rate is controlled at 5-15 μm / h to ensure uniform particle distribution.

[0022] The titanium alloy prepared by the above method of the present invention has the following characteristics:

[0023] a) The material has a multi-level structure inside, including micron-scale grains with a particle size of 1-10 μm, nanoscale grains with a particle size of 10-500 nm, and periodically superimposed nano-layered structures;

[0024] b) The thickness of each layer of the nano-layered structure is 5-100 nm, and the strength and toughness of the material are improved through interface interaction between the layers;

[0025] c) The second phase particles are evenly distributed in the material, and the particles are TiC, TiB 2 , TiN or other intermetallic compounds, with a particle size range of 5-50nm;

[0026] d) After surface treatment, the material exhibits excellent corrosion resistance, with corrosion potential increased by ≥30%; fatigue strength increased by ≥20% and excellent biocompatibility.

[0027] Compared with the prior art, this technical solution mainly solves the following technical problems and has the following beneficial effects:

[0028] 1) It solves the problem that traditional strengthening methods (such as solid solution strengthening and precipitation strengthening) easily lead to the decrease of material ductility and crack propagation resistance, while taking into account both strength and toughness, breaking through the performance balance limit of traditional titanium alloys;

[0029] 2) The fatigue performance is significantly improved by utilizing the barrier effect of the multi-level structure on the crack propagation path. At the same time, the interface effect in the multi-level structure can dissipate the energy in the crack propagation process, thereby effectively inhibiting the rapid propagation of the crack;

[0030] 3) Existing methods for preparing high-performance titanium alloys have certain limitations in microstructure regulation. For example, grain refinement and the uniformity of second-phase distribution are difficult to accurately control, and the formation of multi-level structures requires complex process flows with low repeatability. This solution not only achieves efficient preparation of nano-layered structures and second-phase particles, but also ensures the uniformity of the microstructure and the controllability of the process. At the same time, the process is simple, suitable for large-scale industrial production, reduces production costs, and lays the foundation for the widespread application of multi-level three-dimensional nano-layered titanium alloys. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0032] Example 1

[0033] (1) Titanium alloy billet preparation: Titanium-based alloy billets were prepared using vacuum melting technology to ensure uniform alloy composition and impurity content of less than 0.2 wt %. The billets were processed into an initial shape of 50 mm × 50 mm × 5 mm.

[0034] (2) Accumulative rolling bond (ARB) process: multiple passes of cumulative rolling are carried out at 200°C, with a rolling reduction ratio of 60% for each pass; annealing at 400°C for 20 minutes between passes to maintain ductility; the total deformation reaches more than 90%, and finally a nano-grained titanium alloy is produced, with a preliminary layered structure and a layer thickness of 50-100nm.

[0035] (3) Heat treatment: A homogenization annealing treatment was performed at 600°C for 1 hour to optimize the uniformity and stability of the nano-layered structure.

[0036] (4) Introduction of second phase particles: TiC particles were introduced at 800° C. by chemical vapor deposition (CVD) method, with the deposition rate controlled at 10 μm / h, the particle size being 20 nm, and the mass percentage being 5%.

[0037] (5) Retreatment: Heat treatment temperature is 400°C and time is 60 min.

[0038] Performance test: The prepared titanium alloy was tested and showed that compared with the blank, the yield strength was increased by 30%, the fatigue life was extended by 50%, and the corrosion potential was increased by 35%.

[0039] Example 2

[0040] (1) Titanium alloy billet preparation: Titanium-based alloy billets were prepared using vacuum melting technology to ensure uniform alloy composition and impurity content of less than 0.2 wt %. The billets were processed into an initial shape of 50 mm × 50 mm × 5 mm.

[0041] (2) High-pressure torsion (HPT) process: Apply a torsion pressure of 6 GPa and rotate 15 times; perform cooling control at 100 °C to suppress dynamic recrystallization and obtain nano-scale grains (average grain size of 50 nm); after torsion, a periodically superimposed nano-layered structure is formed with a layer thickness of 10-50 nm.

[0042] (3) Heat treatment: A homogenization annealing treatment was performed at 600°C for 1 hour to optimize the uniformity and stability of the nano-layered structure.

[0043] (4) Introduction of second phase particles: TiC particles were introduced at 800°C by chemical vapor deposition (CVD) method, the deposition rate was controlled at 10 μm / h, the particle size was 20 nm, and the volume fraction was 5%.

[0044] (5) Retreatment: Heat treatment temperature is 400°C and time is 60 min.

[0045] Performance test: The prepared titanium alloy was tested and showed that compared with the blank, the yield strength exceeded 1250MPa and the fatigue crack growth rate was reduced by 40%.

[0046] Example 3

[0047] (1) Titanium alloy billet preparation: Titanium-based alloy billets were prepared using vacuum melting technology to ensure uniform alloy composition and impurity content of less than 0.2 wt %. The billets were processed into an initial shape of 50 mm × 50 mm × 5 mm.

[0048] (2) Accumulative rolling bond (ARB) process: multiple passes of cumulative rolling are carried out at 200°C, with a rolling reduction ratio of 60% for each pass; annealing at 400°C for 20 minutes between passes to maintain ductility; the total deformation reaches more than 90%, and finally a nano-grained titanium alloy is produced, with a preliminary layered structure and a layer thickness of 50-100nm.

[0049] (3) Heat treatment: A homogenization annealing treatment was performed at 600°C for 1 hour to optimize the uniformity and stability of the nano-layered structure.

[0050] (4) Introduction of second phase particles: TiN particles were introduced at 800° C. by chemical vapor deposition (CVD) method, with the deposition rate controlled at 15 μm / h, the particle size being 10 nm, and the volume fraction being 7%.

[0051] (5) Retreatment: Heat treatment temperature is 400°C and time is 60 min.

[0052] Performance test: Tests on the prepared titanium alloy show that the tensile strength of the material reaches 1400MPa. Compared with the blank, the corrosion resistance is improved by 50%, and the wear resistance is improved by about 60%. It is suitable for key components in aviation and marine environments.

[0053] Example 4

[0054] (1) Titanium alloy billet preparation: Titanium-based alloy billets were prepared using vacuum melting technology to ensure uniform alloy composition and impurity content of less than 0.2 wt %. The billets were processed into an initial shape of 50 mm × 50 mm × 5 mm.

[0055] (2) High-pressure torsion (HPT) process: Apply a torsion pressure of 6 GPa and rotate 15 times; perform cooling control at 100 °C to suppress dynamic recrystallization and obtain nano-scale grains (average grain size of 50 nm); after torsion, a periodically superimposed nano-layered structure is formed with a layer thickness of 10-50 nm.

[0056] (3) Heat treatment: A homogenization annealing treatment was performed at 600°C for 1 hour to optimize the uniformity and stability of the nano-layered structure.

[0057] (4) Introduction of the second-phase particles: Introduce TiB2 particles by CVD at 1000 °C, with a deposition rate of 12 μm / h, a particle size of 30 nm, and a volume fraction of 3%.

[0058] (5) Reprocessing: The temperature of the heat treatment is 400 °C and the time is 60 min.

[0059] Performance test: The prepared titanium alloy shows through testing that, compared with the billet, its corrosion resistance (the corrosion potential is increased by 40%) and biocompatibility are suitable for medical implants.

Claims

1. A method for preparing a multi-level three-dimensional nano-layered titanium alloy, characterized in that: The following steps are involved: (1) Preparation of titanium-based alloy billets: Titanium-based alloy billets are prepared by vacuum melting, plasma rotating electrode method PREP or powder metallurgy technology; (2) Reshaping deformation: The titanium-based alloy billet is plastically deformed by cumulative rolling ARB or high pressure torsion HPT technology, with a total deformation of ≥ 90%, so that the matrix grains are refined to the nanoscale and a preliminary layered structure is formed; (3) heat treatment: heat treating the product of step (2) to form a stable nano-layered structure; (4) Introduction of second phase particles: TiC, TiB2, TiN particles or other intermetallic compounds are uniformly distributed in the titanium alloy matrix through chemical vapor deposition CVD or powder metallurgy; (5) Reprocessing: The product of step (4) is heat-treated again to form a multi-level three-dimensional nano-layered titanium alloy.

2. The method for preparing the multi-level three-dimensional nano-layered titanium alloy according to claim 1, characterized in that: In step (1), the impurity content of the titanium-based alloy blank is less than 0.2wt%.

3. The method for preparing the multi-level three-dimensional nano-layered titanium alloy according to claim 1, characterized in that: In step (2), the specific steps of cumulative rolling ARB include: a) The rolling reduction ratio of each pass is 50%-80%; b) The rolling temperature is controlled at 200-400°C to avoid excessive hardening of the material; c) Intermediate annealing is performed between passes at 400°C for 20 minutes.

4. The method for preparing the multi-level three-dimensional nano-layered titanium alloy according to claim 1, characterized in that: In step (2), the specific steps of high pressure torsion HPT include: a) Torsional pressure ≥5GPa, number of revolutions ≥10 turns; b) controlled cooling at 100 °C to suppress dynamic recrystallization and ensure the integrity of the lamellar structure; c) Combined with hydrogenation treatment, the hydrogen embrittlement induction method is used to further refine the grains.

5. The method for preparing the multi-level three-dimensional nano-layered titanium alloy according to claim 1, characterized in that: In step (3), the heat treatment temperature is 300-800°C and the heat treatment time is 1 hour.

6. The method for preparing the multi-level three-dimensional nano-layered titanium alloy according to claim 1, characterized in that: In step (4), the specific conditions of the CVD process are: a) the reaction temperature is 800-1000° C.; b) the particle deposition rate is controlled at 5-15 μm / h.

7. The method for preparing a multi-level three-dimensional nano-layered titanium alloy according to claim 1, characterized in that: In step (4), the mass of the introduced TiC, TiB2, TiN particles or other intermetallic compounds accounts for 1%-10% of the mass of the titanium alloy.

8. The method for preparing a multi-level three-dimensional nano-layered titanium alloy according to claim 1, characterized in that: In step (5), the heat treatment temperature is 300-800°C and the heat treatment time is 30-60 minutes.

9. The multi-level three-dimensional nano-layered titanium alloy prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The interior of the multi-level three-dimensional nano-layered titanium alloy has a multi-level structure, including micron-scale grains with a particle size of 1-10 μm, nano-scale grains with a particle size of 10-500 nm, and periodically superimposed nano-layered structures; the thickness of each layer of the nano-layered structure is 5-100 nm.

10. The multi-level three-dimensional nano-layered titanium alloy according to claim 9, characterized in that: The introduced second phase particles have a particle size range of 5-50 nm.