Preparation method of microtexture heterostructure titanium alloy and microtexture heterostructure titanium alloy

Abstract

The invention relates to the technical field of titanium alloys, in particular to a preparation method of a microtexture heterostructure titanium alloy and the microtexture heterostructure titanium alloy. The preparation method of the microtexture heterostructure titanium alloy comprises the following steps that titanium alloy powder obtained after hydrotreating and hydrogenated and dehydrogenated titanium powder are mixed and pressed into a blank, sintering and hot extrusion are conducted, and alpha-Ti in the obtained titanium alloy forms lt in the direction parallel to the hot extrusion direction; 0001 gt, 0001 gt; and meanwhile, the material has a heterostructure of an isometric crystal and an alpha-Ti / beta-Ti lamellar structure. Titanium alloy powder subjected to hydrotreating and hydrogenated and dehydrogenated titanium powder are mixed, so that the strength of a pressed blank is improved, the oxygen content is reduced, the sintering temperature is reduced, meanwhile, different recrystallization degrees occur in the sintering and thermal deformation process, different grain sizes, crystal orientations and phase distributions are presented, and the lt is actively constructed; 0001 gt, 0001 gt; the microtexture heterostructure titanium alloy material achieves comprehensive improvement of strength, plasticity, fracture toughness and other properties.

Description

Technical Field

[0001] This invention relates to the field of titanium alloy technology, specifically to a method for preparing a microtextured heterostructure titanium alloy and the microtextured heterostructure titanium alloy. Background Technology

[0002] The mismatch between tensile strength and plasticity is a major obstacle to the engineering application of intrinsically oxygen-rich powder metallurgy titanium alloys. Traditional powder metallurgy titanium alloys typically have an oxygen content above 0.35 wt%, which hinders dislocation slip, easily leads to premature cracking at grain boundaries, and results in a sharp decrease in plasticity. Improving the strength-plasticity balance in powder metallurgy titanium alloys is a problem that urgently needs to be solved.

[0003] Firstly, regarding powder raw materials, in samples prepared by element-mixed powder metallurgy, titanium alloy powder undergoes oxidation during ball milling. Furthermore, as the milling time increases, the particle size decreases and the oxygen content increases. The oxygen content of ball-milled titanium alloy powder fluctuates between 0.21 and 0.6 wt%. Pre-alloyed powder, obtained through rapid solidification, generally has an oxygen content less than 0.1 wt%. In additive manufacturing, titanium or titanium alloy powder prepared by gas atomization or rotating electrode methods requires sieving (e.g., laser selective melting requires a powder particle size of 10–53 μm), resulting in a waste rate exceeding 50% for ultrafine powder (<10 μm) and coarse powder (>120 μm). Even after multiple recycling cycles, the oxygen content of pre-alloyed powder is far lower than that of ball-milled titanium alloy powder. These pre-alloyed powders have relatively uniform internal structure, good surface finish, and high deformation resistance, but are prone to collapse during pressing. Developing and reusing these pre-alloyed powder byproducts to manufacture high-quality titanium alloy parts at low cost has significant economic benefits and engineering application value.

[0004] Secondly, regarding microstructure properties, previous studies have fully demonstrated the superiority of heterogeneous microstructures in synergistically improving the strength and ductility of alloys. Introducing the concept of microstructural heterogeneity, multi-scale heterogeneous structural materials were designed, exhibiting significant advantages in balancing alloy strength and ductility that are difficult to match by traditional homogeneous structural materials. Through the microscopic asynchronous deformation effect of heterogeneous structures, the plastic incompatibility at the heterogeneous interface induces a strain gradient, generating more geometrically required dislocations (GNDs) and heterogeneous deformation-induced (HDI) stress, significantly improving strain hardening capacity, effectively suppressing strain localization, and facilitating coordinated deformation, thus solving the problem of the strength-plasticity contradiction.

[0005] Chinese patent application CN118792544A, published on October 18, 2024, discloses a high-strength and high-toughness martensitic heterostructure titanium alloy, its preparation method, and its applications. The method involves pressing and sintering Ti-6Al-4V alloy powder (particle diameter 50-150 μm) to obtain a billet; using a hot extrusion process (extrusion ratio 5-18), the billet is plastically deformed to obtain a formed part; the formed part is processed into a sheet and used as a resistance thermometer, heated by applying voltage, controlling the energizing time, and then water-quenched to obtain a martensitic heterostructure titanium alloy. By combining powder metallurgy, hot extrusion, and resistance heating, the microstructure of the material can be controlled, enabling the preparation of a martensitic heterostructure titanium alloy with a microstructure including elongated crystals, equiaxed α-Ti, and martensite, while simultaneously improving the material's strength and toughness.

[0006] Currently, the processing technology for heterostructured titanium alloys mostly adopts large-deformation hot working combined with subsequent heat treatment, which is energy-intensive, has high deformation resistance, and places stringent requirements on equipment. Developing processing and preparation technologies that are low-cost, easy to implement, and highly controllable is crucial for promoting the development and commercial application of heterostructured materials. Summary of the Invention

[0007] The first objective of this invention is to provide a method for preparing a microtextured heterostructure titanium alloy, which solves the problem that existing powder metallurgy titanium alloys cannot simultaneously achieve low oxygen content, high density, high strength, and high toughness.

[0008] The second objective of this invention is to provide a microtextured heterostructure titanium alloy that solves the problem that existing powder metallurgy titanium alloys cannot simultaneously achieve low oxygen content, high density, high strength, and high toughness.

[0009] To solve the above-mentioned technical problems, the technical solution of the microtextured heterostructure titanium alloy preparation method of the present invention is as follows: A method for preparing a microtextured heterostructure titanium alloy includes the following steps: mixing hydrogenated titanium alloy powder and hydrogenated dehydrogenated titanium powder, pressing them into a billet, and then sintering and hot extruding the resulting titanium alloy, in which α-Ti coarse grain regions are formed parallel to the hot extrusion direction. <0001> Microtexture, a heterostructure that simultaneously possesses equiaxed crystals and α-Ti / β-Ti lamellar structures.

[0010] This invention improves upon existing technologies by providing a method for preparing a microtextured heterostructure titanium alloy. By hydrogenating titanium alloy powder and then mixing it with hydrogenated and dehydrogenated titanium powder, the compressibility and compact strength of spherical titanium alloy powder are effectively enhanced, preventing the compact from crumbling upon demolding. The hydrogenated titanium alloy transforms into titanium hydride, which is easily broken, helping to eliminate argon pockets within the spherical powder. The hydrogenated and dehydrogenated pure titanium powder exhibits diverse shapes, sizes, and morphologies. The mixed powder particles can fill the gaps, resulting in a tighter bond between particles, enhanced interfacial bonding, and improved compact strength. This ensures the compact retains its shape after demolding, with a compaction density of no less than 95%. The overall powder exhibits reduced sensitivity to pressing temperature, enabling compressive forming over a wider temperature range from room temperature, further improving the adaptability of titanium alloy powder particle size. This invention's preparation method can utilize titanium alloy powder recovered during additive manufacturing. These powders have poor sphericity and flowability, making them unsuitable for additive manufacturing, thus enabling further resource utilization and reducing production costs.

[0011] During the sintering process, titanium hydride undergoes a dehydrogenation reaction, releasing active hydrogen atoms and reducing surface oxides. The fresh titanium surface after dehydrogenation generates a large number of lattice defects, which helps diffusion and mass transfer, promotes the sintering process, and helps to reduce the sintering temperature when forming titanium alloy powder.

[0012] The reducing atmosphere of the hydrogenation process in titanium alloy powder reduces the thickness of the oxide film on the powder surface, resulting in an oxygen content in the final material that is generally below 0.13 wt%, and can even reach 0.095 wt%, which is far lower than that of traditional powder metallurgy titanium alloys (oxygen content is generally above 0.35 wt%). The low oxygen content can significantly improve the plastic processing capability and damage tolerance of titanium alloys, reduce the risk of hydrogen embrittlement, and improve work hardening. This high density and low oxygen content make it more reliable and stable in engineering applications.

[0013] After sintering and forming, the compact undergoes subsequent thermomechanical processing, achieving a material density exceeding 99.9%. During extrusion, the ductile pure titanium region acts as the soft phase, while the alloy powder region acts as the hard phase. Both are uniformly distributed at the microscale. The pure titanium region is more prone to severe deformation, and at high temperatures, the β-grains... <110> The crystal orientation is parallel to the extrusion direction. During the β→α solid-state phase transition, the α-lamellae preferentially grow according to the orientation relationship (0001)α / / {110}β, making them easier to form. <0001> A specific microtexture with α parallel to the extrusion direction. Due to the compositional gradient between titanium alloy and pure titanium, the titanium alloy region undergoes hydrogen-rich phase decomposition during dehydrogenation, generating an ultrafine α-Ti and β-Ti lamellar structure. The pure titanium region exhibits an equiaxed crystal morphology, while the titanium alloy region exhibits an α / β fine lamellar structure. Constructing a titanium alloy with a two-scale heterogeneous structure featuring microtexture can achieve a synergistic improvement in the strength and toughness of titanium alloy materials.

[0014] It is understandable that the coarse-grained region refers to the pure titanium region formed by hydrogenation and dehydrogenation of titanium.

[0015] Preferably, the mass ratio of hydrogenated titanium alloy powder to hydrogenated dehydrogenated titanium powder is (2~3):1.

[0016] Preferably, the particle size of the titanium alloy powder used for hydrogenation is 60~350μm; the hydrogen content of the hydrogenated titanium alloy powder is 2.5~4.0wt%.

[0017] Preferably, after hot extrusion, annealing is performed at a temperature of 850-1000℃ for 1-2 hours. After annealing, nano-needle-like α-phase precipitates within the β-matrix, forming a heterolayered mixed-crystal α / βt structure with a specific microtexture. After annealing, the pure titanium region retains... <0001> The microtexture parallel to the extrusion direction, with Mo element distribution promoting the formation of a βt composite structure. This nanoneedle-like α-phase-enhanced βt composite structure can induce microscopic asynchronous deformation effects. Simultaneously, controlling the cluster size within a reasonable range (average lamellar cluster size ≤50μm) allows for synergistic effects of orientation and size, improving the deformation uniformity of the material and suppressing strain localization. The mixed-grained α / βt composite titanium alloy exhibits plastic incompatibility at the heterogeneous interface, inducing strain gradients and geometrically required dislocations (GNDs), providing the material with stronger strain hardening capabilities. This enables a comprehensive improvement in strength, plasticity, and fracture toughness, meeting the stringent performance requirements of various engineering applications.

[0018] Preferably, the sintering temperature is 900~1100℃, the sintering time is 5~40min, and the sintering is carried out under vacuum conditions or an inert atmosphere.

[0019] Preferably, the hot extrusion temperature is 900~1000℃ and the extrusion ratio is 9~16:1.

[0020] Preferably, the hydrogenation treatment involves holding the titanium alloy powder at 200-300°C under vacuum for 1-2 hours, followed by holding it at 550-700°C in a hydrogen atmosphere at a pressure of 0.7-1 bar. The holding time at 550-700°C in a hydrogen atmosphere is determined by the time the hydrogen pressure stabilizes.

[0021] Preferably, the pressure during pressing is 600~1000MPa and the time is 30~90s.

[0022] Preferably, the titanium alloy powder is a spherical pre-alloyed powder, and the hydrogenated dehydrogenated titanium powder is irregularly shaped. The titanium alloy powder comprises titanium, 3-6.5% Al, and no more than 4% other metallic elements, wherein the other metallic elements are selected from one or more of V, Zr, and Mo. The irregular shape of the hydrogenated dehydrogenated titanium powder means that it is non-spherical. The "no more than 4% other metallic elements" means that the content of each other metallic element does not exceed 4%.

[0023] The technical solution of the microtextured heterostructure titanium alloy of the present invention is as follows: A microtextured heterostructured titanium alloy prepared by the aforementioned method.

[0024] The microtextured heterostructure titanium alloy of the present invention is prepared by the aforementioned preparation method, constructing a multi-scale heterostructure containing different grain sizes, orientations and phase distributions. This ingeniously produces a multi-scale heterostructure powder metallurgy titanium alloy material with a specific microtexture, high purity, high strength and high plasticity, and low cost. This titanium alloy has high strength, elongation and fracture toughness. Attached Figure Description

[0025] Figure 1 This is a diagram showing the internal microstructure of the titanium alloy after hot extrusion in Example 1 of the present invention. Figure 2 This is a diagram showing the internal microstructure of the titanium alloy after annealing in Example 1 of the present invention. Figure 3 The images show scanning electron microscope (SEM) images of the microstructure of the heterostructured titanium alloy with microtexture in Example 1 of this invention and the crystal orientation results obtained from EBSD analysis. Figure 4 This is a stress-strain curve diagram of the titanium alloy before and after annealing in Example 1 of the present invention; Figure 5 This is an internal microstructure diagram of the titanium alloy after annealing treatment in Example 2 of the present invention; Figure 6 This is a stress-strain curve of the titanium alloy after annealing in Example 2 of the present invention. Detailed Implementation

[0026] The technical concept of the method for preparing microtextured heterostructured titanium alloys provided by this invention is as follows: Existing technology involves pressing titanium alloy powder into shape, then sintering and hot extruding it. The hot-extruded sample is then used as a resistor to apply voltage for heat treatment. By controlling the energizing time, water quenching is performed to obtain a titanium alloy with a martensitic heterostructure, thereby improving the material's strength and toughness.

[0027] This invention provides a low-cost manufacturing method for microtextured heterostructure titanium alloys, utilizing coarse powder byproducts from additive manufacturing of unusable spherical powders and hydrogenated, dehydrogenated pure titanium powder. The hydrogenated spherical pre-alloyed powder transforms into brittle titanium hydride, which rapidly breaks down during pressing, mixing with irregular pure titanium powder. This improves the particle bonding force and compactness of the pressed compact, ultimately increasing its strength. During sintering, a dehydrogenation reaction occurs, releasing hydrogen atoms, increasing sintering activity and significantly reducing the sintering temperature. After sintering, a certain amount of dissolved hydrogen remains, reducing the high-temperature deformation resistance of the titanium alloy. The innovation of this invention lies in its pioneering utilization of the deformation characteristics of different powders, combined with hydrogenation treatment. The pre-alloyed and pure titanium regions undergo different degrees of recrystallization during sintering and hot deformation, exhibiting different grain sizes, crystal orientations, and phase distributions, actively constructing a... <0001> Microtextured heterostructure titanium alloys. This opens up a new avenue for the low-cost preparation of high-performance heterostructure titanium alloys.

[0028] The method for preparing microtextured heterostructure titanium alloys provided by this invention includes the following steps: 1) Recycling Titanium Alloy Powder: The recycled titanium alloy powder is spherical titanium alloy powder (i.e., spherical pre-alloyed powder) produced by crucibleless electrode induction gas atomization (EIGA) or plasma rotating electrode (PREP) methods that cannot be reused in additive manufacturing. The particle size of the recycled titanium alloy powder is 60~350μm. These powders have poor sphericity and flowability, and their particle size is not within the acceptable range for additive manufacturing. The titanium alloy powder includes titanium, 3~6.5% Al, and no more than 4% other metallic elements, wherein the other metallic elements are selected from one or more of V, Zr, and Mo; the titanium alloy is selected from one or more of Ti-6Al-4V, Ti-6.5Al-2Zr-1Mo-1V, and Ti-3Al-2Zr-2Mo.

[0029] 2) Hydrogenation treatment: The hydrogenation treatment involves holding titanium alloy powder at 200~300℃ for 1~2 hours under vacuum, and then holding it at 550~700℃ in a hydrogen atmosphere until the hydrogen pressure stabilizes; the hydrogen pressure in the hydrogen atmosphere is 0.7~1 bar. The coarse titanium alloy powder undergoes a phase transformation during hydrogenation, transforming into spherical titanium hydride powder.

[0030] In step 2), the vacuum level under vacuum conditions is 5 × 10⁻⁶. -3 ~1×10 -2 Pa.

[0031] In step 2), when the heat treatment is carried out under vacuum conditions, the heating rate to the heat treatment temperature is 5~10℃ / min; when the heat treatment is carried out under hydrogen conditions, the heating rate to the heat treatment temperature is 5~10℃ / min.

[0032] In step 2), after the heat preservation treatment in the hydrogen environment is completed, the furnace is cooled to 200~250℃, and then inert gas is introduced to replace the hydrogen.

[0033] In step 2), the hydrogen content of the hydrogenated titanium alloy powder is 2.5~4.0 wt%.

[0034] 3) Raw material mixing: The hydrogenated titanium alloy powder and the hydrogenated dehydrogenated titanium powder are mixed to obtain a mixed powder; the hydrogenated dehydrogenated titanium powder has an irregular shape and a particle size of less than 3 mm. More preferably, the hydrogenated dehydrogenated titanium powder is obtained by passing it through an 80-mesh sieve.

[0035] In step 3), the mixing is carried out in a double cone mixer; the rotation speed is 20~50 r / min, and the mixing time is 24~36 h.

[0036] In step 3), the mass ratio of hydrogenated titanium alloy powder to hydrogenated dehydrogenated titanium powder is (2~3):1.

[0037] 4) Compact Forming: The mixed powder is pressed into a compact. The pressure during compaction is 600~1000MPa, and the time is 30~90s. Compaction is carried out in an H13 steel mold. During the pressing process, the spherical coarse titanium hydride powder particles are simultaneously crushed, interlocked, and densified. Combined with irregular hydrogenated dehydrogenated titanium powder, the interlocking force between the powders further improves the compact's strength and density.

[0038] 5) Low-temperature sintering and hot extrusion: The mixed powder is sintered at a temperature of 900-1100℃ for 5-40 minutes under vacuum or inert atmosphere. After sintering, hot extrusion is performed at a temperature of 900-1000℃ with an extrusion ratio of 9-16:1; preferably, the sintering temperature is 1000-1100℃. After hot extrusion, annealing is performed at a temperature of 850-1000℃ for 1-2 hours. The resulting titanium alloy exhibits a coarse α-Ti grain region parallel to the hot extrusion direction. <0001> Microtexture, a heterostructure that simultaneously possesses equiaxed crystals and α-Ti / βt composite lamellar structures.

[0039] In step 5), when sintering is performed under vacuum conditions, the vacuum level is (4.0~5.0)×10⁻¹⁰. -3 Pa. The inert gas is argon.

[0040] In step 5), the heating method for sintering can be either resistance heating or induction coil heating. When using resistance heating, the heating rate to the sintering temperature is 5~8℃ / min, and the holding time is 30~40min; when using induction coil heating, the heating rate to the sintering temperature is 100~120℃ / min, and the holding time is 5~10min.

[0041] In step 5), the residual dissolved hydrogen content in the sintered sample is ≤0.15wt%.

[0042] The embodiments of the present invention will be further described below with reference to specific examples. Unless otherwise specified, the chemical reagents involved in the following examples are all commercially available conventional products.

[0043] I. The preparation method of the microtextured heterostructure titanium alloy of the present invention and specific embodiments of the microtextured heterostructure titanium alloy. Example 1 The method for preparing the microtextured heterostructure titanium alloy in this embodiment is as follows: 1) Recycling Ti75 titanium alloy coarse powder (Ti-3Al-2Zr-2Mo): Recycling pre-alloyed powder that can no longer be used for additive manufacturing. The Ti75 spherical titanium alloy powder produced by plasma rotating electrode method (PREP) or gas atomization method is vibrated and screened to separate coarse powder with a particle size of 120~350 μm.

[0044] 2) Hydrogenation treatment: The Ti75 titanium alloy coarse powder recovered in step 1) is loaded into the molybdenum boat of the hydrogenation furnace for hydrogenation. The hydrogenation process is as follows: First, a vacuum is drawn to 5.0 × 10⁻⁶ m³ / h. -3 The temperature was increased to 200°C at 8°C / min and held for 1 hour. Then, hydrogen was introduced, maintaining the hydrogen pressure in the furnace at 0.80 bar. The temperature was slowly increased to 660°C at 5°C / min and held until the hydrogen pressure in the furnace stabilized. Finally, the furnace was cooled to 200°C in a hydrogen atmosphere, argon was introduced, and the hydrogen was vented. Hydrogenated Ti75 titanium alloy powder with a hydrogen content of 3.5 wt% was obtained.

[0045] 3) Raw material mixing: Transfer the hydrogenated Ti75 titanium alloy powder obtained in step 2) into a glove box protected by argon atmosphere, mix it with irregular hydrogenated dehydrogenated titanium powder (Liaoning Chaoyang Jinda Titanium Industry, passed through an 80-mesh sieve), the mass ratio of hydrogenated Ti75 titanium alloy powder to hydrogenated dehydrogenated titanium powder is 2:1, put it into a double cone powder mixer, run at a speed of 20 r / min for 24 h to obtain mixed powder.

[0046] 4) Powder Compacting: The mixed powder from step 3) is transferred into an H13 steel mold for pressing and molding. After demolding, a powder compact is obtained. A layer of graphite paper is laid on the mold wall for lubrication. The pressing force is controlled at 750 MPa, and the holding time is 50 seconds. During the pressing process, the hydrogenated Ti75 titanium alloy powder particles are simultaneously broken, increasing the density and strength of the powder compact. Sufficient in-situ breakage of the powder particles is achieved, eliminating gaps between particles and ensuring adequate particle engagement.

[0047] 5) Low-temperature sintering and hot extrusion: Vacuum sintering of the powder compacts obtained in step 4): Several powder compacts are loaded into a vacuum sintering furnace, and a vacuum is first drawn to 5.0 × 10⁻⁶. -3 Pa, then the temperature was increased to 1000℃ at 5℃ / min and held for 30min to complete sintering. A large amount of hydrogen was released during the sintering process, and the residual dissolved hydrogen content in the final sintered sample was 0.10wt%.

[0048] Finally, the sintered Ti75 titanium alloy billet was reheated to 1000℃ and held for 5 minutes, then transferred to an extruder to complete the extrusion molding with an extrusion ratio of 16:1 to obtain hot extruded bars. The die material used for hot extrusion was H13 steel. After the die was preheated, the sintered sample was placed in it. The preheating temperature was 550℃.

[0049] The internal microstructure of the titanium alloy obtained in this embodiment is shown in the following figure. Figure 1 As shown, Figure 1 (a) and (b) are microstructure images at different magnifications. The pure titanium region exhibits an equiaxed crystal morphology, while the pre-alloyed region exhibits an α / β lamellar structure.

[0050] The heterostructured titanium alloy extruded bar prepared in this embodiment has an oxygen content of only 0.095 wt% and a density of 99.9%. After annealing at 880℃ / 1h / AC (air cooling), nano-needle-like secondary α phase precipitates inside the β matrix, forming an α / βt composite layered structure, such as... Figure 2 As shown, Figure 2 (a) and (b) are tissue morphology images at different magnifications. Figure 3 This image shows a scanning electron microscope (SEM) image of the microstructure of the fabricated heterostructure titanium alloy. Figure 3 (a) and the crystal orientation results of EBSD analysis ( Figure 3 (bc) It can be seen that the titanium alloy manufactured by this invention has a uniform and fine microstructure, with an average lamellar cluster size ≤50 μm. <0001> Parallel to the extrusion direction. Figure 4 The stress-strain curves of the titanium alloy before and after annealing are shown. Figure 4 (a) shows the engineering stress-strain curves of the titanium alloy before and after annealing. Figure 4(b) shows the true stress-strain diagram and work hardening rate of the titanium alloy before and after annealing. The room temperature tensile strength of the fine lamellar titanium alloy extruded bar is 680 MPa, the elongation at break is 10.0%, and the fracture toughness reaches 80 MPa. m 1 / 2 The room temperature tensile strength of the composite layered titanium alloy extruded bar reaches 767 MPa, the elongation at break reaches 19%, and the fracture toughness reaches 112 MPa. m 1 / 2 .

[0051] The titanium alloy prepared in this embodiment, before and after annealing, is the microtextured heterostructure titanium alloy provided by this invention.

[0052] Compared to traditional cast Ti75 alloy bars (commercially available titanium alloys, Northwest Nonferrous Metals Research Institute), the powder metallurgy titanium alloy manufactured by this invention achieves a 50 MPa increase in tensile strength and a 25% increase in elongation at break while maintaining lower oxygen content and higher density. Compared to traditional powder metallurgy titanium alloys manufactured using irregular element powders, the powder metallurgy titanium alloy manufactured by this invention controls the oxygen content at the level of ultra-low interstitial titanium alloys, while increasing room temperature elongation at break and fracture toughness by 30%.

[0053] Example 2 The method for preparing the microtextured heterostructure titanium alloy in this embodiment is as follows: 1) Recycling TA15 titanium alloy coarse powder (Ti-6.5Al-2Zr-1Mo-1V): Powder with incomplete sphericity and particle size distribution outside the specified range can be used in this embodiment. The raw material in this embodiment is a powder by-product that is no longer used in the additive manufacturing plant. The particle size of TA15 titanium alloy coarse powder is 60~220μm.

[0054] 2) Hydrogenation treatment: The TA15 titanium alloy coarse powder recovered in step 1) is loaded into the molybdenum boat of the hydrogenation furnace for hydrogenation. The hydrogenation process is as follows: First, a vacuum is drawn to 1.0 × 10⁻⁶ m³ / h. -2 The furnace was heated to 250°C at a rate of 8°C / min and held for 1 hour. Then, hydrogen was introduced, maintaining the hydrogen pressure in the furnace at 0.90 bar. The temperature was slowly increased to 670°C at a rate of 5°C / min and held until the hydrogen pressure in the furnace stabilized. Finally, the furnace was cooled to 200°C in a hydrogen atmosphere, then high-purity argon was introduced, and the hydrogen was vented. Hydrogenated TA15 titanium alloy powder with a hydrogen content of 3.8 wt% was obtained.

[0055] 3) Raw material mixing: The hydrogenated TA15 titanium alloy powder and hydrogenated dehydrogenated titanium powder obtained in step 2) are loaded into a double cone mixer at a mass ratio of 2:1. The mixture is then transferred to an argon-atmosphere protected glove box and sealed. Afterwards, it is run at 20 rpm for 24 hours.

[0056] 4) Pressing: The mixed powder from step 3) is transferred into an H13 steel mold and pressed. After demolding, a powder compact is obtained. The pressing force is controlled at 900 MPa, the holding time is 30 seconds, and a layer of graphite paper is laid on the mold wall for lubrication.

[0057] 5) Low-temperature sintering and hot extrusion: The powder compact obtained in step 4) was subjected to rapid induction coil heating sintering: Under an argon atmosphere, the alloy powder compact was placed in an induction coil and heated to 1100 °C at a rate of 100 °C / min, held for 5 min to complete sintering, with a residual dissolved hydrogen content of 0.09 wt%. After sintering, the compact was quickly transferred to an extrusion die for hot extrusion at 1000 °C (extrusion ratio 9:1). The die material used for hot extrusion was H13 steel, and the sintered sample was placed in the preheated die at a preheating temperature of 550 °C.

[0058] The TA15 titanium alloy extruded bar prepared in this embodiment has an oxygen content of 0.13 wt% and a density of 99.90%. After conventional annealing treatment (980℃ / 1h / AC), as... Figure 5 As shown, a heterogeneous TA15 titanium alloy sample with a specific microtexture was obtained. This sample achieved a room temperature tensile strength of 950 MPa and a fracture elongation of 8.0%, as shown. Figure 6 As shown, the tensile strength reaches 820 MPa at 500℃.

[0059] The titanium alloy prepared in this embodiment, before and after annealing, is the microtextured heterostructure titanium alloy provided by this invention. In other embodiments, spherical coarse titanium alloy powder without hydrogenation treatment is used, which cannot be pressed into compacts.

[0060] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a microtextured heterostructure titanium alloy, characterized in that, Includes the following steps: Hydrogenated titanium alloy powder and hydrogenated dehydrogenated titanium powder are mixed and pressed into a billet, which is then sintered and hot extruded. The resulting titanium alloy has α-Ti coarse grain regions formed parallel to the hot extrusion direction. <0001> Microtexture, a heterostructure that simultaneously possesses equiaxed crystals and α-Ti / β-Ti lamellar structures.

2. The method for preparing microtextured heterostructure titanium alloys as described in claim 1, characterized in that, The mass ratio of hydrogenated titanium alloy powder to hydrogenated dehydrogenated titanium powder is (2~3):

1.

3. The method for preparing microtextured heterostructure titanium alloys as described in claim 1, characterized in that, The particle size of the titanium alloy powder used for hydrogenation treatment is 60~350μm; the hydrogen content of the hydrogenated titanium alloy powder is 2.5~4.0wt%.

4. The method for preparing a microtextured heterostructure titanium alloy according to any one of claims 1-3, characterized in that, After hot extrusion, an annealing treatment is performed at a temperature of 850~1000℃ for 1~2 hours.

5. The method for preparing a microtextured heterostructure titanium alloy according to any one of claims 1-3, characterized in that, The sintering temperature is 900~1100℃, the sintering time is 5~40min, and the sintering is carried out under vacuum conditions or inert atmosphere.

6. The method for preparing a microtextured heterostructure titanium alloy according to any one of claims 1-3, characterized in that, The hot extrusion temperature is 900~1000℃, and the extrusion ratio is 9~16:

1.

7. The method for preparing a microtextured heterostructure titanium alloy as described in claim 1 or 3, characterized in that, The hydrogenation treatment involves holding titanium alloy powder at 200-300°C for 1-2 hours under vacuum, followed by holding it at 550-700°C in a hydrogen atmosphere; the hydrogen pressure is 0.7-1 bar.

8. The method for preparing a microtextured heterostructure titanium alloy according to any one of claims 1-3, characterized in that, The pressure during pressing into a blank is 600~1000MPa, and the time is 30~90s.

9. The method for preparing a microtextured heterostructure titanium alloy according to any one of claims 1-3, characterized in that, The titanium alloy powder is a spherical pre-alloyed powder, and the hydrogenated dehydrogenated titanium powder is an irregular shape; the titanium alloy powder includes titanium, 3 to 6.5% Al and no more than 4% other metal elements, wherein the other metal elements are selected from one or more of V, Zr and Mo.

10. A microtextured heterostructured titanium alloy prepared by the method for preparing a microtextured heterostructured titanium alloy as described in any one of claims 1-9.

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