Preparation method and application of low-elasticity-modulus titanium alloy

Abstract

The invention discloses a preparation method and application of a low-elasticity-modulus titanium alloy, titanium alloy powder comprises three elements of Ti, Nb and O, and the components comprise 13-22 wt% of Nb, 0.3-0.9 wt% of O and the balance Ti and other inevitable impurities. The Ti-Nb-O powder prepared through the method can be applied to 3D printing and hot pressing sintering technologies to directly form a block, the microstructure of the block is regulated and controlled through a post-treatment technology, the block has the characteristics of being low in elasticity modulus, high in strength, excellent in biocompatibility and the like, the room-temperature elasticity modulus of the Ti-Nb-O powder is 35-55 GPa, the yield strength can reach 800-1000 MPa, the ductility is larger than 10%, and the Ti-Nb-O powder can be used for preparing a high-strength material. The method has important theoretical significance and engineering value, and is suitable for manufacturing biological implantation medical devices.

Description

Technical Field

[0001] The invention relates to a preparation method and application of a low elastic modulus titanium alloy, belonging to the field of titanium alloy powder preparation technology and application. Background Art

[0002] Titanium alloys are widely used as load-bearing implant materials in orthopedic and trauma surgery due to their high yield strength and excellent fatigue resistance. However, the negative effects of metal ion release and "stress shielding" caused by the mismatch of elastic modulus are challenges faced by the current use of titanium alloys. For example, the elastic modulus of Ti-6Al-4V (110GPa) and Ti-6Al-7Nb (105GPa) far exceeds that of human bone tissue (10-30GPa). Therefore, the development of new titanium alloys with good biocompatibility, high strength and low modulus is crucial to meet the needs of advanced biomedical high-performance applications.

[0003] Reducing the stability of the β phase is conducive to reducing the Young's modulus. Therefore, the Young's modulus of many metastable β-Ti alloys developed is between 55 and 80 GPa, but is usually accompanied by lower strength (less than 600 MPa); oxygen-doped titanium alloys have obvious interstitial solid solution strengthening effects on α and β phases, and are accompanied by excellent biocompatibility, although they are still traditionally classified as impurities in Ti alloys, affecting the plasticity of the alloy; but studies have found that by strictly controlling its content and regulating the microstructure, synergistic enhancement of strength and ductility can be obtained. National invention patent CN107805740B discloses a low elastic modulus medical implant titanium alloy, in which the Nb content is 30-33wt%, the Zr content is 1-6wt%, the Mo content is 2-4wt%, the O content is 0.2-0.4wt%, and the balance is Ti. The elastic modulus of the alloy can reach 55 GPa after cold rolling + heat treatment, but the preparation process is complicated, and the addition of more types of alloying elements brings risks to the safety of clinical applications.

[0004] Currently, most metal implants are produced using traditional processing technology. The preparation process is expensive, time-consuming, and cannot meet the needs of individualized treatment. 3D printing and hot pressing sintering are common technologies in titanium alloy powder metallurgy. Using powdered metal materials to build objects can improve the production quality and mechanical properties of products, while reducing the time and manufacturing complexity required for product design and production. However, most research and development work on low-modulus titanium alloys is mainly focused on single β-phase alloys. This titanium alloy powder with high β-phase stability undergoes multiple melting between different layers during the 3D printing preparation process, and the cooling rate is extremely fast, resulting in coarse and uneven metallographic structure, usually with low yield strength, making it difficult to achieve a good match between low modulus and high strength, and the overall performance of the material cannot be guaranteed. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for preparing a titanium alloy with a low elastic modulus. By designing the alloy composition and combining the preparation process, the elastic modulus of the titanium alloy is reduced to less than 55 GPa while ensuring the strength of the titanium alloy; the comprehensive performance of the alloy is significantly improved.

[0006] The technical solution of the present invention is: a method for preparing a low elastic modulus titanium alloy, which prepares a low modulus high strength titanium alloy by selecting alloy elements and combining a heat treatment process.

[0007] The titanium alloy raw material components include 13-22wt% of Nb, 0.3-0.9wt% of O and the balance of Ti, as well as other inevitable impurity elements.

[0008] The preparation process of the titanium alloy specifically comprises the following steps:

[0009] (1) Sponge titanium, Nb particles and TiO2 powder are mixed, smelted to prepare a Ti-Nb-O titanium alloy ingot, and the Ti-Nb-O titanium alloy ingot is processed into titanium alloy powder.

[0010] Preferably, a titanium alloy ingot is prepared by vacuum consumable arc melting technology according to a composition ratio of 13 to 22 wt% Nb, 0.3 to 0.9 wt% O, and the balance Ti, and the ingot is further turned into a cast rod, and the cast rod is subjected to plasma rotating electrode atomization or vacuum air atomization under inert gas conditions to obtain a Ti-Nb-O titanium alloy powder with an average particle size of less than 110 μm and good sphericity.

[0011] (2) The titanium alloy powder prepared in step (1) is directly molded into a Ti-Nb-O titanium alloy billet using 3D printing technology or hot pressing sintering technology.

[0012] (3) A two-step annealing process is adopted: after the heating furnace is heated to 750-850°C, the Ti-Nb-O titanium alloy billet is placed in the heating furnace for 1-2 hours, furnace cooled to 550-650°C at a rate of 5-15°C / min and kept for 1-2 hours, and then taken out and air-cooled to room temperature; a stable α+β two-phase structure with a size gradient is obtained, so that the two-phase alloy has excellent comprehensive properties such as high strength and low elastic modulus at a relatively high oxygen content, and can be used to prepare biological implant medical devices, such as artificial knee joints, hip joints, femoral stems, caval bones, medullary bones, screws and tooth roots.

[0013] Preferably, in the 3D printing process in step (2) of the present invention, the particle size range of the Ti-Nb-O titanium alloy powder is 15 to 53 μm; the parameters of the 3D printing process are: scanning power 260 to 320 W, scanning speed 1000 to 1500 mm / s, and scanning spacing 0.05 to 0.11 mm.

[0014] Preferably, during the hot pressing sintering process in step (2) of the present invention, the particle size range of the Ti-Nb-O titanium alloy powder is 53-106 μm; the parameters of the hot pressing sintering process are: sintering temperature at 900-1100°C, sintering pressure at 25-50 MPa, pressing time at 10-20 min, and keeping at the sintering temperature for 1-3 h.

[0015] Preferably, the Ti—Nb—O titanium alloy structure of the present invention comprises a lamellar two-phase structure with a size gradient structure, wherein the volume fraction of the α phase is 45% to 60%.

[0016] The principle of the present invention is as follows: the temperature is controlled in the single-phase region through the molding technology to obtain a β matrix + needle-shaped martensite structure; through a two-step annealing post-processing design scheme, the distribution and content of the α phase in the above-mentioned block microstructure are regulated, so that the grain boundary α phase is discontinuous and equiaxed, and the content of the α phase in the crystal is in the range of 45% to 60%, and finally the characteristics of high strength and low elastic modulus are obtained.

[0017] The titanium alloy prepared from the Ti-Nb-O powder of the present invention has a room temperature elastic modulus of less than 55 GPa, a yield strength of more than 800 MPa, an elongation of more than 10%, and has the characteristics of high strength, high plasticity, low elastic modulus and excellent biocompatibility, and is suitable for making biological implant medical devices.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] (1) The low modulus titanium alloy powder of the present invention reduces the stability of the β-phase structure and combines high oxygen concentration doping to obtain a large amount of needle-shaped martensite structure, which solves the problem of coarse and uneven structure of the powder during 3D printing and hot pressing sintering, and has important theoretical significance and engineering value.

[0020] (2) The present invention controls the size of the α phase by designing a two-step annealing post-processing process, annealing at a higher temperature to form a large lamellar α phase, and then annealing at a lower temperature to form a secondary small lamellar α phase, thereby realizing a lamellar structure with a size gradient and solving the key problem of the mismatch between the plasticity and strength of the lamellar organization.

[0021] (3) The present invention achieves the matching of ultra-low elastic modulus and high strength in the two-phase titanium alloy by controlling the temperature and time of the two-step annealing, accurately regulating the content and morphology of the α phase, and adjusting the structural stability of the remaining β phase. The post-processing process is simple to operate and is suitable for industrial production.

[0022] (4) After 3D printing and hot pressing sintering, the low modulus and high strength titanium alloy powder of the present invention is combined with the post-processing process design, and the elastic modulus of the alloy is 35 to 55 GPa, the yield strength can reach 800 to 1000 MPa, and the elongation is greater than 10%. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. The features and advantages of the present invention will be more clearly understood by referring to the drawings. The drawings are schematic and should not be construed as limiting the present invention in any way. For those skilled in the art, other drawings can be obtained based on these drawings without creative work; among them:

[0024] Figure 1 This is the SEM morphology of the titanium alloy powder prepared in Example 1 of the present invention.

[0025] Figure 2 This is a tissue morphology diagram of the powder prepared in Example 1 of the present invention applied to 3D printing technology.

[0026] Figure 3 The mechanical property curves of the powders prepared in Examples 1, 2, 3 of the present invention and Comparative Examples 1 and 2 when applied to 3D printing technology.

[0027] Figure 4 This is the organizational morphology diagram of comparative example 1 of the present invention. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention will be described clearly and completely below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other; the following examples are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0030] Example 1

[0031] A method for preparing a low elastic modulus titanium alloy specifically comprises the following steps:

[0032] (1) Prepare titanium sponge, Nb particles, and TiO2 powder raw materials, and mix them according to the above alloy component ratios, wash the raw materials and other steps to remove surface oxides and impurities; place the raw materials in a vacuum consumable furnace for smelting to obtain a Ti-Nb-O alloy ingot, and further turn it into a Φ30 mm cast rod.

[0033] (2) The cast rod is subjected to plasma rotary electrode atomization powdering under argon conditions, and the prepared spherical powder is sieved to screen out Ti-Nb-O alloy powder with a particle size of 15 to 53 μm.

[0034] (3) The Ti-Nb-O alloy powder was dried in a vacuum drying oven at 80°C for 2 h, and then 3D printed. The molding parameters were: laser power 280 W, scanning speed 1100 mm / s, scanning spacing 0.09 mm, single layer powder thickness 0.04 mm, scanning strategy was a layer-by-layer deflection 67° printing method, and Ti-6Al-4V was used as the substrate to obtain the Ti-18Nb-0.7O alloy material prepared by 3D printing.

[0035] (4) The Ti-18Nb-0.7O alloy material prepared by 3D printing was subjected to a two-step annealing process: the material was kept at 830°C for 2 h, furnace cooled to 600°C at a rate of 10°C / min and kept at that temperature for 1 h, and then air-cooled to room temperature to obtain an annealed Ti-18Nb-0.7O alloy.

[0036] The SEM morphology of the Ti-18Nb-0.7O titanium alloy powder prepared in this example is as follows: Figure 1 As shown in the figure, the powder has a high sphericity and no satellite powder. After 3D printing, the alloy density is greater than 99.9%, and the alloy phase composition is β matrix + needle-shaped martensite; after two-step annealing, equiaxed discontinuous α phase precipitates at the grain boundary, and lamellar α phase with different size gradients precipitates in the crystal, and the α phase content is 58% (as shown in the figure). Figure 2 ); Typical tensile curves are as follows Figure 3 As shown, the titanium alloy prepared from the powder by 3D printing technology has an ultra-low modulus of 39 GPa, a yield strength of 803 MPa, a tensile strength of 945 MPa, and an elongation of 15%.

[0037] Comparative Example 1

[0038] The composition and preparation method of the titanium alloy powder described in this embodiment are the same as those in Example 1, except that the post-treatment method is a one-step annealing process, that is, the powder is kept at 830° C. for 2 hours and then cooled to room temperature to obtain an annealed Ti-18Nb-0.7O alloy.

[0039] The Ti-18Nb-0.7O powder prepared in this comparative example was formed by 3D printing technology. After one-step annealing, the α phase content increased significantly to 75% (e.g. Figure 4 ), and due to the large temperature gradient, the extension of diffusion time makes the grain boundary α phase continuous and coarse; the tensile curve is as follows Figure 3As shown, at this time, the elastic modulus is 86 GPa, the yield strength is 1036 MPa, and the elongation is 6%; by comparing Example 1 with Example 1, it can be seen that the one-step annealing process causes a significant increase in the α phase content, thereby greatly increasing the modulus of the alloy while reducing the plasticity.

[0040] Comparative Example 2

[0041] The titanium alloy powder composition of this embodiment is Ti-8Nb-0.2O, and its preparation and post-treatment methods are the same as those in Embodiment 1. It is formed by 3D printing technology and combined with a two-step annealing process to obtain an annealed alloy.

[0042] The tensile curve of Ti-8Nb-0.2O prepared in this comparative example is as follows Figure 3 As shown, the elastic modulus is 75 GPa, the yield strength is 665 MPa, and the elongation is 18%. By comparing Examples 1 and 2, it is shown that the reduction of Nb and O content reduces the stability of the β matrix and significantly reduces the strength of the alloy.

[0043] Example 2

[0044] A method for preparing a low elastic modulus titanium alloy specifically comprises the following steps:

[0045] (1) Prepare titanium sponge, Nb particles, and TiO2 powder raw materials, and wash the raw materials according to the above alloy component ratios to remove surface oxides and impurities; place the raw materials in a vacuum consumable melting furnace for melting to obtain a Ti-Nb-O alloy ingot, which is further turned into a Φ30 mm cast rod.

[0046] (2) The cast rod is subjected to plasma rotary electrode atomization powdering under argon conditions, and the prepared spherical powder is sieved to screen out Ti-Nb-O alloy powder with a particle size of 15 to 53 μm.

[0047] (3) The Ti-Nb-O alloy powder was dried in a vacuum drying oven at 80° C. for 2 h, and then 3D printed. The molding parameters were the same as those in Example 1 to obtain a Ti-18Nb-0.7O alloy material prepared by 3D printing.

[0048] (4) The Ti-22Nb-0.9O alloy material prepared by 3D printing was subjected to a two-step annealing process: the material was kept at 750°C for 2 h, furnace cooled to 550°C at a rate of 5°C / min and kept at this temperature for 2 h, and then air-cooled to room temperature to obtain an annealed Ti-22Nb-0.9O alloy.

[0049] The Ti-22Nb-0.9O titanium alloy powder prepared in this embodiment is formed by 3D printing technology. After two-step annealing, the typical tensile curve is as follows: Figure 3As shown, it has an elastic modulus of 52 GPa, a yield strength of 934 MPa, a tensile strength of 1036 MPa, and an elongation of 10%.

[0050] Example 3

[0051] A method for preparing a low elastic modulus titanium alloy specifically comprises the following steps:

[0052] (1) Prepare titanium sponge, Nb particles, and TiO2 powder raw materials, and wash the raw materials according to the above alloy component ratios to remove surface oxides and impurities; place the raw materials in a vacuum consumable melting furnace for melting to obtain a Ti-Nb-O alloy ingot, which is further turned into a Φ30 mm cast rod.

[0053] (2) The cast rod is subjected to plasma rotary electrode atomization powdering under argon conditions, and the prepared spherical powder is sieved to screen out Ti-Nb-O alloy powder with a particle size of 15 to 53 μm.

[0054] (3) The Ti-Nb-O alloy powder was dried in a vacuum drying oven at 80° C. for 2 h, and then 3D printed with the same molding parameters as in Example 1 to obtain a Ti-13Nb-0.3O alloy material prepared by 3D printing.

[0055] (4) The Ti-13Nb-0.3O alloy material prepared by 3D printing was subjected to a two-step annealing process, wherein the material was kept at 850°C for 1 h, furnace cooled to 650°C at a rate of 15°C / min and kept for 1 h, and then air-cooled to room temperature to obtain an annealed Ti-13Nb-0.3O alloy.

[0056] The Ti-13Nb-0.3O titanium alloy powder prepared in this embodiment is formed by 3D printing technology. After two-step annealing, the typical tensile curve is as follows: Figure 3 As shown, it has an elastic modulus of 46 GPa, a yield strength of 895 MPa, a tensile strength of 987 MPa, and an elongation of 12.5%.

[0057] Example 4

[0058] A method for preparing a low elastic modulus titanium alloy specifically comprises the following steps:

[0059] (1) Prepare titanium sponge, Nb particles, and TiO2 powder raw materials, and wash the raw materials according to the above alloy component ratios to remove surface oxides and impurities; place the raw materials in a vacuum consumable melting furnace for melting to obtain a Ti-Nb-O alloy ingot, which is further turned into a Φ30 mm cast rod.

[0060] (2) The cast rod is subjected to plasma rotary electrode atomization powdering under argon conditions, and the prepared spherical powder is sieved to screen out Ti-Nb-O alloy powder with a particle size of 53 to 106 μm.

[0061] (3) The Ti-Nb-O alloy powder was dried in a vacuum drying oven at 80°C for 2 h, and then vacuum hot-pressed and sintered. The molding parameters were as follows: sintering temperature of 1000°C, sintering pressure of 35 MPa, pressing time of 15 min, and heat preservation at the sintering temperature for 1 h to obtain a Ti-18Nb-0.7O alloy material prepared by hot pressing and sintering.

[0062] (4) The Ti-18Nb-0.7O alloy material prepared by hot pressing and sintering was subjected to a two-step annealing process, wherein the material was kept at 830°C for 2 h, furnace cooled to 600°C at a rate of 10°C / min and kept at this temperature for 1 h, and then air-cooled to room temperature to obtain an annealed Ti-18Nb-0.7O alloy.

[0063] The Ti-18Nb-0.7O titanium alloy powder prepared in this embodiment is formed by hot pressing sintering technology. After two-step annealing, the elastic modulus is 36 GPa, the yield strength is 815 MPa, and the elongation is 13.5%.

[0064] Comparative Example 3

[0065] The composition and preparation method of the titanium alloy powder described in this embodiment are the same as those in Example 4, except that the post-treatment method is a one-step annealing process, that is, keeping at 800°C for 2 hours and cooling to room temperature to obtain an annealed Ti-18Nb-0.7O alloy.

[0066] The Ti-18Nb-0.7O powder prepared in this comparative example is formed by hot pressing sintering technology. After one-step annealing, the α-phase content increases, the elastic modulus is 92 GPa, the yield strength is 957 MPa, and the elongation is 7.5%.

[0067] Comparative Example 4

[0068] The titanium alloy powder composition of this embodiment is Ti-8Nb-0.2O, and its preparation and post-treatment methods are the same as those of embodiment 4. It is formed by hot pressing sintering technology and combined with a two-step annealing process to obtain an annealed alloy.

[0069] The Ti-8Nb-0.2O prepared in this comparative example has an elastic modulus of 80 GPa and a yield strength of 680 MPa, which are much lower than those of Examples 4, 5 and 6, and an elongation of 17%.

[0070] Example 5

[0071] A method for preparing a low elastic modulus titanium alloy specifically comprises the following steps:

[0072] (1) Prepare titanium sponge, Nb particles, and TiO2 powder raw materials, and wash the raw materials according to the above alloy component ratios to remove surface oxide impurities; place the raw materials in a vacuum consumable melting furnace for melting to obtain a Ti-Nb-O alloy ingot, which is further turned into a Φ30 mm cast rod.

[0073] (2) The cast rod is subjected to plasma rotary electrode atomization powdering under argon conditions at a working speed of 15000 rpm; the prepared spherical powder is sieved to screen out Ti-Nb-O alloy powder with a particle size of 53 to 106 μm.

[0074] (3) The Ti-Nb-O alloy powder was dried in a vacuum drying oven at 80°C for 2 h, and then vacuum hot-pressed and sintered. The specific molding parameters were: sintering temperature of 1000°C, sintering pressure of 35 MPa, pressing time of 15 min, and heat preservation at the sintering temperature for 1 h to obtain a Ti-14Nb-0.4O alloy material prepared by hot pressing and sintering.

[0075] (4) The Ti-22Nb-0.9O alloy material prepared by the above press sintering was subjected to a two-step annealing process: the material was kept at 750°C for 2 h, furnace cooled to 550°C at a rate of 5°C / min and kept at this temperature for 2 h, and then air-cooled to room temperature to obtain an annealed Ti-22Nb-0.9O alloy.

[0076] The Ti-22Nb-0.9O titanium alloy powder prepared in this embodiment is formed by hot pressing sintering technology. After two-step annealing, the elastic modulus is 47 GPa, the yield strength is 875 MPa, and the elongation is 10.5%.

[0077] Example 6

[0078] A method for preparing a low elastic modulus titanium alloy specifically comprises the following steps:

[0079] (1) Prepare titanium sponge, Nb particles, and TiO2 powder raw materials, and wash the raw materials according to the above alloy component ratios to remove surface oxide impurities; place the raw materials in a vacuum consumable melting furnace for melting to obtain a Ti-Nb-O alloy ingot, which is further turned into a Φ30 mm cast rod.

[0080] (2) The cast rod is subjected to plasma rotary electrode atomization powdering under argon conditions at a working speed of 15000 rpm; the prepared spherical powder is sieved to screen out Ti-Nb-O alloy powder with a particle size of 53 to 106 μm.

[0081] (3) The Ti-Nb-O alloy powder was dried in a vacuum drying oven at 80°C for 2 h, and then vacuum hot-pressed and sintered. The specific molding parameters were: sintering temperature of 1000°C, sintering pressure of 35 MPa, pressing time of 15 min, and heat preservation at the sintering temperature for 1 h to obtain a Ti-14Nb-0.4O alloy material prepared by hot pressing and sintering.

[0082] (4) The Ti-14Nb-0.4O alloy material prepared by hot pressing sintering was subjected to a two-step annealing process: the material was kept at 850°C for 1 hour, furnace cooled to 650°C at a rate of 15°C / min and kept for 1 hour, and then air-cooled to room temperature to obtain an annealed Ti-13Nb-0.3O alloy.

[0083] The Ti-13Nb-0.3O titanium alloy powder prepared in this embodiment is formed by hot pressing sintering technology. After two-step annealing, the elastic modulus is 55 GPa, the yield strength is 910 MPa, and the elongation is 12%.

[0084] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an ultra-low elastic modulus titanium alloy, characterized in that: Low modulus and high strength titanium alloys are prepared by selecting alloying elements and combining heat treatment processes; The titanium alloy raw material composition includes 13-22wt% Nb, 0.3-0.9wt% O and the balance Ti, as well as other inevitable impurity elements; The preparation process of the titanium alloy specifically comprises the following steps: (1) mixing titanium sponge, Nb particles and TiO2 powder, smelting to prepare a Ti-Nb-O titanium alloy ingot, and processing the Ti-Nb-O titanium alloy ingot into titanium alloy powder; (2) directly forming the titanium alloy powder prepared in step (1) by 3D printing technology or hot pressing sintering technology to obtain a Ti-Nb-O titanium alloy blank; (3) A two-step annealing process is adopted: after the heating furnace is heated to 750-850°C, the Ti-Nb-O titanium alloy billet is placed in the heating furnace for 1-2 hours, furnace cooled to 550-650°C at 5-15°C / min and kept for 1-2 hours, and then taken out and air-cooled to room temperature.

2. The method for preparing a low elastic modulus titanium alloy according to claim 1, characterized in that: In step (1), a vacuum consumable furnace is used for smelting.

3. The method for preparing a low elastic modulus titanium alloy according to claim 1, characterized in that: During the 3D printing process in step (2), the particle size range of the Ti-Nb-O titanium alloy powder is 15 to 53 μm.

4. The method for preparing a low elastic modulus titanium alloy according to claim 3, characterized in that: The preparation method of Ti-Nb-O titanium alloy powder in step (1) includes a plasma rotating electrode method and a vacuum gas atomization method.

5. The method for preparing a low elastic modulus titanium alloy according to claim 1, characterized in that: During the hot pressing and sintering process in step (2), the particle size range of the Ti-Nb-O titanium alloy powder is 53-106 μm.

6. The method for preparing a low elastic modulus titanium alloy according to claim 5, characterized in that: The parameters of the 3D printing process in step (2) are: scanning power 260-320 W, scanning speed 1000-1500 mm / s, and scanning spacing 0.05-0.11 mm.

7. The method for preparing a low elastic modulus titanium alloy according to claim 1, characterized in that: The parameters of the hot pressing sintering process in step (2) are: sintering temperature at 900-1100° C., sintering pressure at 25-50 MPa, pressing time at 10-20 min, and keeping at the sintering temperature for 1-3 h.

8. The method for preparing a low elastic modulus titanium alloy according to claim 1, characterized in that: The Ti-Nb-O titanium alloy structure comprises a lamellar two-phase structure with a size gradient structure, wherein the volume fraction of the α phase is 45% to 60%.

9. The Ti-Nb-O titanium alloy obtained by the method according to any one of claims 1 to 8 can be used in biological implantable medical devices.

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