Titanium-niobium alloy double gradient material and preparation method thereof

Abstract

The application discloses a titanium-niobium alloy double-gradient material and a preparation method thereof, and belongs to the field of gradient material preparation. The application utilizes an electron beam additive manufacturing technology, controls the temperature of a powder bed, controls the precipitation quantity and distribution of an alpha" phase from a beta phase, forms double-gradient changes of the volume fraction and the elastic modulus of the precipitated phase along a preset direction, and finally successfully prepares the titanium-niobium alloy double-gradient material. The method is highly controllable, the combined action of the precipitation phase gradient and the elastic modulus gradient in the prepared double-gradient material significantly improves the impact resistance of the additive manufactured titanium alloy material, and the production is simple, the production cost is low, the efficiency is high, and the method has high further research and application values.

Description

Technical Field

[0001] This invention belongs to the field of gradient material preparation, specifically relating to a titanium-niobium alloy dual gradient material and its preparation method. Background Technology

[0002] Titanium-niobium alloys are typical β-type titanium alloys, possessing advantages such as high specific strength and high corrosion resistance, and are widely used in important fields such as medical devices, aerospace, and aviation. Gradient structure refers to a material's property or microstructure exhibiting a systematic and continuous variation along a certain dimension on a macroscopic scale. Researchers have found that gradient materials in nature, such as teeth and bamboo, often possess excellent combinations of properties. Furthermore, dual-gradient materials often exhibit superior performance combinations compared to single-gradient materials. Therefore, constructing a dual-gradient structure in titanium-niobium based alloys can significantly improve their performance, enabling them to better serve in high-end applications.

[0003] Patent CN 116536537 A discloses a heterogeneous titanium alloy and its preparation method, which obtains a titanium alloy material with a single composition gradient by adjusting the initial metal powder concentration and depositing it through laser melting; Patent CN114888289A discloses a gradient titanium-based composite material and its preparation method, which obtains a titanium-based composite material with a single gradient of precipitated phase content through powder hot pressing sintering; Patent CN 115475959 A discloses a preparation method of a NiTi-based shape memory alloy with a dual gradient of composition and structure, which obtains a porous NiTi-based alloy material with dual gradients of composition and structure through laser powder bed melting process; Patent CN 116079071 A discloses an electron beam melting manufacturing method for TiAl gradient materials, which obtains a titanium alloy material with a gradient of composition concentration by adjusting the powder ratio.

[0004] The above patents disclose relevant technical solutions for obtaining compositional or structural gradients. However, there is currently no relevant technology that can construct a dual gradient of precipitate content and elastic modulus in titanium-niobium based alloys. Summary of the Invention

[0005] In view of this, and to address the aforementioned pressing problems, this invention provides a method for preparing a titanium-niobium alloy dual-gradient material. This method utilizes electron beam additive manufacturing technology to control the temperature of the powder bed, thereby controlling the quantity and distribution of the α” phase precipitated from the β phase, forming a gradient change in the precipitated phase and elastic modulus along a predetermined direction. In this invention, utilizing this principle, a titanium-niobium alloy dual-gradient material was successfully prepared. This method is highly controllable, simple to produce, low in production cost, and highly efficient, possessing significant value for further research and development and application.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A titanium-niobium alloy dual-gradient material, wherein the alloy used is a Ti-Nb alloy.

[0008] The titanium-niobium alloy dual-gradient material includes an α”-rich phase region, a β-rich phase region, and an intermediate transition phase region, ultimately forming a material with a phase gradient distribution of α”→β and a modulus gradient.

[0009] The volume content of the dual-gradient material phases and the elastic modulus of the titanium-niobium alloy are both distributed in a gradient along the α” phase → β phase direction.

[0010] The content of precipitated phases in the microstructure changes continuously along a preset direction, and the elastic modulus of the material changes continuously along a preset direction, forming a dual gradient of precipitated phase volume fraction gradient and elastic modulus gradient; the preset direction is upward along the bottom plate, α” phase → β phase.

[0011] In the precipitated phase, the content of the α” phase changes monotonically along a preset direction, and the volume fraction of the α” phase can reach up to 50%.

[0012] In the precipitated phase, the β phase content changes monotonically along a preset direction.

[0013] The elastic modulus changes monotonically along a preset direction, with a modulus range of 40~80GPa and a maximum difference of 35GPa.

[0014] The preparation method of the titanium-niobium alloy dual-gradient material adopts electron beam additive manufacturing technology for integral molding, and specifically includes the following steps:

[0015] Step 1: Prepare an alloy package, controlling the mass percentage of Nb in the alloy composition to be 23%~26%, the mass fraction of O to be 0.1%~0.6%, with the balance being Ti, and perform vacuum melting;

[0016] Step 2: Hot rolling and billet preparation, with the billet temperature controlled at 700~1200℃ and the billet deformation controlled at 10%~50%;

[0017] Step 3: Rolling deformation, controlling the rolling temperature at 300~700℃, and the rolling reduction at 10%~50%;

[0018] Step 4: Cooling, controlling the cooling rate at 10~30℃ / minute; cool to room temperature;

[0019] Step 5; Aging: Perform room temperature aging treatment for 1-2 days to obtain titanium-niobium alloy.

[0020] Step 6: Prepare titanium-niobium alloy spherical powder using the titanium-niobium alloy obtained in Step 5.

[0021] Step 7: Design the gradient model and import the model into the electron beam control equipment control system;

[0022] Step 8: Set process parameters;

[0023] Step 9: Perform pre-printing processing. Rotate the support column to adjust the printing direction and height, and adjust the substrate to be horizontal. Adjust the amount of powder picked up by the powder collector in a single pass until snowflake patterns appear evenly on the substrate surface. Adjust the powder picking amount so that the time for the powder collector to pass through the powder flow sensor is 150-180ms.

[0024] Step 10: After reaching the predetermined state, start printing. During the printing process, adjust the process parameters according to the gradient model.

[0025] Step 11: Printing complete, inert gas is introduced for protection. In step 6, the preparation method is either gas atomization or a rotating electrode; the powder particle size distribution range is 46μm~106μm, and the particle size distribution must meet the following requirements: D10 45-50μm, D50 70-80μm, D90 95-110μm; the loose packing density is 2.8-3.0g / cm³. 3 The tap density is 3.2-3.4 g / cm³. 3 The hollow pasta content shall not exceed 0.5%.

[0026] In step 7, the gradient direction of the gradient material model must be consistent with the printing direction.

[0027] In step 8, the initial printing plate temperature is required to be 450-600℃;

[0028] In step 8, the preheating process parameters for the α-rich phase region are: Beam current 18-20mA; Beam speed 8000-12000mm / s; Number of repetitions 14-16.

[0029] In step 8, the preheating process parameters for the β-rich region are: Beam current 15-18 mA; Beam speed 12000-15000 mm / s; Number of repetitions 10-14.

[0030] In step 8, the energy density of the printing process parameters for the α”-rich phase region is 45-55 J / mm². 3 The energy density of the printing process parameters in the β-phase-rich region is 35-45 J / mm². 3 .

[0031] In step 10, after the α-rich phase region is printed, the process is switched to the β-rich phase region process to print the transition phase region and the β-rich phase region.

[0032] This technical solution must be strictly followed according to the given steps; adding or subtracting steps will not yield the gradient material.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] 1. This invention provides a method for preparing a titanium-niobium alloy dual-gradient material, which utilizes the highly adjustable nature of electron beam additive manufacturing technology to integrally form a titanium-niobium alloy material with a precipitate phase gradient and an elastic modulus gradient; both the phase content and the elastic modulus change monotonically along a preset direction, wherein the phase content varies from 0 to 50% and the elastic modulus varies from 40 to 80 GPa.

[0035] 2. This invention provides a titanium-niobium alloy dual-gradient material. The combined effect of the precipitate phase gradient and the elastic modulus gradient significantly improves the impact resistance of additively manufactured titanium alloy materials, reducing the impact toughness of typical additively manufactured titanium alloys from less than 15 J / cm. 2 The current yield is 18-22 J / cm. 2 Between these two periods, the increase was approximately 20%-47%.

[0036] 3. The preparation method of the titanium-niobium alloy dual gradient material of the present invention is simple, and gradient materials with complex shapes can be prepared by electron beam additive manufacturing technology, which has good application prospects. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the gradient distribution of the titanium-niobium alloy dual-gradient material prepared in Example 1;

[0038] Figure 2 This is a scanning image of the microstructure of the α-rich phase region in Example 1;

[0039] Figure 3 This is a scanning image of the microstructure of the transition phase region in Example 1;

[0040] Figure 4 This is a scanning image of the microstructure of the β-rich phase region in Example 1;

[0041] Figure 5 This is a scanning image of the microstructure of the α”-rich phase region in Example 2;

[0042] Figure 6 This is a scanning image of the microstructure of the transition phase region in Example 2;

[0043] Figure 7 This is a scanning image of the microstructure of the β-rich phase region in Example 2;

[0044] Figure 8 This is a scanning image of the microstructure of the α”-rich phase region in Example 3;

[0045] Figure 9 This is a scanning image of the microstructure of the transition phase region in Example 3;

[0046] Figure 10 This is a scanning image of the microstructure of the β-rich phase region in Example 3. Detailed Implementation

[0047] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments. The following embodiments are merely some examples of the present invention and are not intended to limit the scope of the invention.

[0048] Example 1

[0049] Step 1: Prepare the alloy package, control the mass percentage of Nb in the alloy composition to be 24%, control the mass percentage of O to be 0.22%, and the balance to be Ti, and perform vacuum melting;

[0050] Step 2: Hot rolling and billet preparation, with the billet temperature controlled at 950℃ and the billet deformation controlled at 20%;

[0051] Step 3: Rolling deformation, controlling the rolling temperature at 600℃ and the rolling reduction at 45%;

[0052] Step 4: Cooling, controlling the cooling rate at 30℃ / minute; cool to room temperature;

[0053] Step 5; Aging: Perform room temperature aging treatment for 2 days to obtain titanium-niobium alloy;

[0054] Step 6: Prepare titanium-niobium alloy spherical powder using the titanium-niobium alloy obtained in Step 5;

[0055] Spherical titanium-niobium alloy powder with a specified composition was prepared using a gas atomization process. The powder particle size distribution ranged from 46 μm to 106 μm, and its powder properties required to meet the following particle size distribution requirements: D10 = 48.2 μm, D50 = 71.5 μm, and D90 = 98 μm. The loose packing density was 2.95 g / cm³. 3 The tap density is 3.35 g / cm³. 3 The hollow pasta content shall not exceed 0.5%.

[0056] Step 7: Design the gradient model and import the model into the electron beam control equipment control system;

[0057] Design a gradient printing model, place the α-rich phase region end on the base plate, place the β-rich phase region on the top of the printing plate, and import the 3D model into the electron beam control equipment control system. Select a base plate of appropriate size according to the size of the printing model.

[0058] Step 8: Set process parameters;

[0059] The scanning strategy is a layer-by-layer 90° deflection printing method, with a substrate temperature of 500℃. The preheating process parameters for the α”-rich phase region are: Beam current 20mA; Beam speed 11500mm / s; Number of repetitions 15. The preheating process parameters for the β-rich phase region are: Beam current 15mA; Beam speed 15000mm / s; Number of repetitions 12. The energy density for the printing process parameters of the α”-rich phase region is 50J / mm². 3 The energy density of the printing process parameters for the β-rich region is 40 J / mm². 3 ;

[0060] Step 9: Perform pre-printing processing. Rotate the support column to adjust the printing direction and height, and adjust the substrate to be horizontal. Adjust the amount of powder picked up by the powder collector in a single pass until snowflake patterns appear evenly on the substrate surface. Adjust the powder picking amount so that the time for the powder collector to pass through the powder flow sensor is 160ms.

[0061] Step 10: After reaching the predetermined state, start printing. During the printing process, adjust the process parameters according to the gradient model.

[0062] After the α”-rich phase region is printed, the process parameters are changed to those for the β”-rich phase region. The transition and β”-rich phase regions are then printed using these process parameters. At this point, because the preheating process parameters for the α”-rich phase region are at a higher temperature, the temperature will gradually decrease to those for the β”-rich phase region.

[0063] Step 11: After printing, inert gas is introduced for protection.

[0064] Printing size 60mm×20mm×20mm yielded a titanium-niobium alloy dual-gradient material. The alloy's chemical composition, by mass percentage, consisted of 24% Nb, 0.22% oxygen, and the remainder Ti.

[0065] Among them, the microstructure of the α-rich phase region is as follows: Figure 2 As shown in the figure, the black part is the β phase, and the white lamellar part is the α” phase, where the α” phase is abundant; the microstructure of the transition phase region is as follows. Figure 3As shown in the figure, the content of the α” phase has decreased significantly compared to the α”-rich phase region, but there are still many α” phases distributed along the printing direction. The microstructure of the β-rich phase region shows that the content of the α” phase is very low, and it is almost entirely dominated by the β phase. Figure 4 As shown. The gradient distribution is as follows. Figure 1 As shown in the figure, the elastic modulus is higher near the bottom plate and gradually decreases towards the top. Elastic modulus tests were conducted on different parts of the titanium-niobium alloy dual-gradient material. The measured elastic modulus was 75 GPa at the bottom and 40 GPa at the top, with a modulus gradient of 35 GPa. Impact specimens were fabricated, and the measured impact toughness was 21 J / cm². 2 The density of the precipitated α” phase was characterized, with the α” phase content in the α”-rich region being 47% and that in the β-rich region being 2%. The density decreased sequentially in the transition phase region.

[0066] Example 2

[0067] Step 1: Prepare the alloy package, control the mass percentage of Nb in the alloy composition to be 24%, control the mass percentage of O to be 0.22%, and the balance to be Ti, and perform vacuum melting;

[0068] Step 2: Hot rolling and billet preparation, with the billet temperature controlled at 950℃ and the billet deformation controlled at 20%;

[0069] Step 3: Rolling deformation, controlling the rolling temperature at 600℃ and the rolling reduction at 45%;

[0070] Step 4: Cooling, controlling the cooling rate at 30℃ / minute; cool to room temperature;

[0071] Step 5; Aging: Perform room temperature aging treatment for 2 days to obtain titanium-niobium alloy;

[0072] Step 6: Prepare titanium-niobium alloy spherical powder using the titanium-niobium alloy obtained in Step 5;

[0073] Spherical titanium-niobium alloy powder with a specified composition was prepared using a gas atomization process. The powder particle size distribution ranged from 46 μm to 106 μm, and its powder properties required to meet the following particle size distribution requirements: D10 = 47.1 μm, D50 = 71.2 μm, and D90 = 98.3 μm. The loose packing density was 2.90 g / cm³. 3 The tap density is 3.31 g / cm³. 3 The hollow pasta content shall not exceed 0.5%.

[0074] Step 7: Design the gradient model and import the model into the electron beam control equipment control system;

[0075] Design a gradient printing model, placing the α-rich phase region at the bottom of the base plate and the β-rich phase region at the top of the printing plate, and import the 3D model into the electron beam control system. Select a base plate of appropriate size according to the dimensions of the printing model.

[0076] Step 8: Set and use different process parameters to prepare the α”-rich phase region and β-rich phase region of titanium-niobium alloy gradient materials;

[0077] The scanning strategy is a layer-by-layer 90° deflection printing method. The substrate temperature is set to 550℃. The preheating process parameters for the α”-rich phase region are: Beam current 19mA; Beam speed 12000mm / s; Number of repetitions 14. The preheating process parameters for the β-rich phase region are: Beam current 16mA; Beam speed 13500mm / s; Number of repetitions 13. The energy density of the printing process parameters for the α”-rich phase region is 52J / mm². 3 The energy density of the printing process parameters for the β-rich region is 38 J / mm². 3 ;

[0078] Step 9: Perform pre-printing processing. Rotate the support column to adjust the printing direction and height, and adjust the substrate to be horizontal. Adjust the amount of powder picked up by the powder collector in a single pass until snowflake patterns appear evenly on the substrate surface. Adjust the powder picking amount so that the time for the powder collector to pass through the powder flow sensor is 150ms.

[0079] Step 10: After reaching the predetermined state, start printing. During the printing process, adjust the process parameters according to the gradient model.

[0080] Step 11: After printing, inert gas is introduced for protection.

[0081] A titanium-niobium alloy dual-gradient material was obtained by printing a 60mm×20mm×20mm size. The alloy's chemical composition, by mass percentage, consisted of 24% Nb, 0.22% oxygen, and the remainder Ti. The microstructure of the α”-rich phase region is as follows: Figure 5 As shown in the figure, the black part is the β phase, and the white lamellar part is the α” phase, where the α” phase is abundant; the microstructure of the transition phase region is as follows. Figure 6 As shown in the figure, the content of the α” phase has decreased significantly compared to the α”-rich phase region, but there are still many α” phases distributed along the printing direction. The microstructure of the β-rich phase region shows that the content of the α” phase is very low, and it is almost entirely dominated by the β phase. Figure 7As shown, the elastic modulus of different parts of the titanium-niobium alloy dual-gradient material was tested. The elastic modulus at the bottom was measured to be 70 GPa, the elastic modulus at the top was 41 GPa, and the modulus gradient was 29 GPa. Impact specimens were fabricated, and the impact toughness was measured to be 18.7 J / cm². 2 The density of the precipitated α” phase was characterized, with the α” phase content being 42% in the α” phase-rich region and 4% in the β phase-rich region. The density decreased sequentially in the transition phase region.

[0082] Example 3

[0083] Step 1: Prepare the alloy package, control the mass percentage of Nb in the alloy composition to be 24%, control the mass percentage of O to be 0.32%, with the balance being Ti, and perform vacuum melting;

[0084] Step 2: Hot rolling and billet preparation, with the billet temperature controlled at 800℃ and the billet deformation controlled at 30%;

[0085] Step 3: Rolling deformation, controlling the rolling temperature at 400℃ and the rolling reduction at 50%;

[0086] Step 4: Cooling, controlling the cooling rate at 10℃ / minute; cool to room temperature;

[0087] Step 5; Aging: Perform room temperature aging treatment for 2 days to obtain titanium-niobium alloy;

[0088] Step 6: Prepare titanium-niobium alloy spherical powder using the titanium-niobium alloy obtained in Step 5;

[0089] Spherical titanium-niobium alloy powder with a specified composition was prepared using a gas atomization process. The powder particle size distribution ranged from 46 μm to 106 μm, and its powder properties required to meet the following particle size distribution requirements: D10 = 47.5 μm, D50 = 71.9 μm, and D90 = 98.4 μm. The loose packing density was 2.88 g / cm³. 3 The tap density is 3.28 g / cm³. 3 The hollow pasta content shall not exceed 0.5%.

[0090] Step 7: Design the gradient model and import the model into the electron beam control equipment control system;

[0091] Design a gradient printing model, place the α-rich phase region end on the base plate, place the β-rich phase region on the top of the printing plate, and import the 3D model into the electron beam control equipment control system. Select a base plate of appropriate size according to the size of the printing model.

[0092] Step 8: Set and use different process parameters to prepare the α”-rich phase region and β-rich phase region of titanium-niobium alloy gradient materials;

[0093] The scanning strategy is a layer-by-layer 90° deflection printing method, with a substrate temperature of 480℃. The preheating process parameters for the α-rich phase region are: Beam current 18mA; Beam speed 8000mm / s; Number of repetitions 16. The preheating process parameters for the β-rich phase region are: Beam current 15mA; Beam speed 15000mm / s; Number of repetitions 11. The energy density for the printing process parameters of the α-rich phase region is 55J / mm². 3 The energy density of the printing process parameters for the β-rich region is 40 J / mm². 3 ;

[0094] Step 9: Perform pre-printing processing. Rotate the support column to adjust the printing direction and height, and adjust the substrate to be horizontal. Adjust the amount of powder picked up by the powder collector in a single pass until snowflake patterns appear evenly on the substrate surface. Adjust the powder picking amount so that the time for the powder collector to pass through the powder flow sensor is 150ms.

[0095] Step 10: After reaching the predetermined state, start printing. During the printing process, adjust the process parameters according to the gradient model.

[0096] After the α”-rich phase region is printed, the process parameters are changed to those for the β-rich phase region. The transition and β-rich phase regions are then printed using the β-rich phase region process parameters. At this point, because the preheating process parameters for the α”-rich phase region are at a higher temperature, the temperature will gradually decrease to those for the β-rich phase region.

[0097] Step 11: After printing, inert gas is introduced for protection.

[0098] A titanium-niobium alloy dual-gradient material was obtained by printing a 60mm × 20mm × 20mm size. The alloy's chemical composition, by mass percentage, consisted of 24% Nb, 0.32% oxygen, and the remainder Ti. The microstructure of the α”-rich phase region is as follows: Figure 8 As shown in the figure, the black part is the β phase, and the white lamellar part is the α” phase, where the α” phase is abundant; the microstructure of the transition phase region is as follows. Figure 9 As shown in the figure, the content of the α” phase has decreased significantly compared to the α”-rich phase region, but there are still many α” phases distributed along the printing direction. The microstructure of the β-rich phase region shows that the content of the α” phase is very low, and it is almost entirely dominated by the β phase. Figure 10 As shown. The measured elastic modulus at the bottom was 74 GPa, the elastic modulus at the top was 42 GPa, and the modulus gradient was 32 GPa. After being processed into an impact specimen, the impact toughness was measured to be 19.3 J / cm². 2The density of the precipitated α” phase was characterized, with the α” phase content being 45% in the α” phase-rich region and 6% in the β phase-rich region. The density decreased sequentially in the transition phase region.

[0099] Example 4

[0100] Step 1: Prepare the alloy package, control the mass percentage of Nb in the alloy composition to be 24%, control the mass percentage of O to be 0.25%, and the balance to be Ti, and perform vacuum melting;

[0101] Step 2: Hot rolling and billet preparation, with the billet temperature controlled at 950℃ and the billet deformation controlled at 25%;

[0102] Step 3: Rolling deformation, controlling the rolling temperature at 650℃ and the rolling reduction at 40%;

[0103] Step 4: Cooling, controlling the cooling rate at 25℃ / minute; cool to room temperature;

[0104] Step 5; Aging: Perform room temperature aging treatment for 1 day to obtain titanium-niobium alloy.

[0105] Step 6: Prepare titanium-niobium alloy spherical powder using the titanium-niobium alloy obtained in Step 5;

[0106] Spherical titanium-niobium alloy powder with a specified composition was prepared using a gas atomization process. The powder particle size distribution ranged from 46 μm to 106 μm, and its powder properties required the following particle size distribution: D10 = 47.7 μm, D50 = 74.9 μm, and D90 = 99.7 μm. The loose packing density was 2.92 g / cm³. 3 The tap density is 3.33 g / cm³. 3 The hollow pasta content shall not exceed 0.5%.

[0107] Step 7: Design the gradient model and import the model into the electron beam control equipment control system;

[0108] Design a gradient printing model, placing the α-rich phase region at the bottom of the base plate and the β-rich phase region at the top of the printing plate, and import the 3D model into the electron beam control system. Select a base plate of appropriate size according to the dimensions of the printing model.

[0109] Step 8: Set and use different process parameters to prepare the α”-rich phase region and β-rich phase region of titanium-niobium alloy gradient materials;

[0110] The scanning strategy is a layer-by-layer 90° deflection printing method. The substrate temperature is selected as 530℃. The preheating process parameters for the α”-rich phase region are: Beam current 19mA; Beam speed 11000mm / s; Number of repetitions 15. The preheating process parameters for the β-rich phase region are: Beam current 17mA; Beam speed 14000mm / s; Number of repetitions 11. The energy density of the printing process parameters for the α”-rich phase region is 50J / mm². 3 The energy density of the printing process parameters for the β-rich region is 36 J / mm². 3 ;

[0111] Step 9: Perform pre-printing processing. Rotate the support column to adjust the printing direction and height, and adjust the substrate to be horizontal. Adjust the amount of powder picked up by the powder collector in a single pass until snowflake patterns appear evenly on the substrate surface. Adjust the powder picking amount so that the time for the powder collector to pass through the powder flow sensor is 170ms.

[0112] Step 10: After reaching the predetermined state, start printing. During the printing process, adjust the process parameters according to the gradient model.

[0113] Step 11: After printing, inert gas is introduced for protection.

[0114] A titanium-niobium alloy dual-gradient material was obtained by printing a 60mm × 20mm × 20mm sample. The alloy's chemical composition (by mass percentage) consisted of 24% Nb, 0.25% oxygen, and the remainder Ti. The elastic modulus of different parts of the titanium-niobium alloy dual-gradient material was tested, yielding a bottom elastic modulus of 68 GPa, a top elastic modulus of 42 GPa, and a modulus gradient of 26 GPa. Impact test specimens were fabricated, and the impact toughness was measured to be 18.2 J / cm². 2 The density of the precipitated α” phase was characterized, with the α” phase content being 40% in the α” phase-rich region and 3% in the β phase-rich region. The density decreased sequentially in the transition phase region.

[0115] Example 5

[0116] Step 1: Prepare the alloy package, control the mass percentage of Nb in the alloy composition to be 24%, control the mass percentage of O to be 0.25%, and the balance to be Ti, and perform vacuum melting;

[0117] Step 2: Hot rolling and billet preparation, with the billet temperature controlled at 950℃ and the billet deformation controlled at 25%;

[0118] Step 3: Rolling deformation, controlling the rolling temperature at 650℃ and the rolling reduction at 40%;

[0119] Step 4: Cooling, controlling the cooling rate at 25℃ / minute; cool to room temperature;

[0120] Step 5; Aging: Perform room temperature aging treatment for 1 day to obtain titanium-niobium alloy.

[0121] Step 6: Prepare titanium-niobium alloy spherical powder using the titanium-niobium alloy obtained in Step 5;

[0122] Spherical titanium-niobium alloy powder with a specified composition was prepared using a gas atomization process. The powder particle size distribution ranged from 46 μm to 106 μm, and its powder properties required to meet the following particle size distribution requirements: D10 = 48.1 μm, D50 = 73.8 μm, and D90 = 100.3 μm. The loose packing density was 2.89 g / cm³. 3 The tap density is 3.36 g / cm³. 3 The hollow pasta content shall not exceed 0.5%.

[0123] Step 7: Design the gradient model and import the model into the electron beam control equipment control system;

[0124] Design a gradient printing model, placing the α-rich phase region at the bottom of the base plate and the β-rich phase region at the top of the printing plate, and import the 3D model into the electron beam control system. Select a base plate of appropriate size according to the dimensions of the printing model.

[0125] Step 8: Set and use different process parameters to prepare the α”-rich phase region and β-rich phase region of titanium-niobium alloy gradient materials;

[0126] The scanning strategy is a layer-by-layer 90° deflection printing method. The substrate temperature is selected as 510℃. The preheating process parameters for the α”-rich phase region are: Beam current 20mA; Beam speed 12000mm / s; Number of repetitions 16. The preheating process parameters for the β-rich phase region are: Beam current 18mA; Beam speed 14500mm / s; Number of repetitions 14. The energy density of the printing process parameters for the α”-rich phase region is 54J / mm². 3 The energy density of the printing process parameters for the β-rich region is 42 J / mm². 3 ;

[0127] Step 9: Perform pre-printing processing. Rotate the support column to adjust the printing direction and height, and adjust the substrate to be horizontal. Adjust the amount of powder picked up by the powder collector in a single pass until snowflake patterns appear evenly on the substrate surface. Adjust the powder picking amount so that the time for the powder collector to pass through the powder flow sensor is 180ms.

[0128] Step 10: After reaching the predetermined state, start printing. During the printing process, adjust the process parameters according to the gradient model.

[0129] Step 11: After printing, inert gas is introduced for protection.

[0130] A titanium-niobium alloy dual-gradient material was obtained by printing a 60mm × 20mm × 20mm sample. The alloy's chemical composition (by mass percentage) consisted of 24% Nb, 0.25% oxygen, and the remainder Ti. The elastic modulus of different parts of the titanium-niobium alloy dual-gradient material was tested, yielding a bottom elastic modulus of 75 GPa, a top elastic modulus of 47 GPa, and a modulus gradient of 28 GPa. Impact test specimens were fabricated, and the impact toughness was measured to be 18.6 J / cm². 2 The density of the precipitated α” phase was characterized, with the α” phase content being 44% in the α” phase-rich region and 6% in the β phase-rich region. The density decreased sequentially in the transition phase region.

Claims

1. A titanium-niobium alloy dual-gradient material, characterized in that, It includes an α”-rich phase region, an intermediate transition phase region, and a β-rich phase region. The volume content of the phases and the elastic modulus of the titanium-niobium alloy dual-gradient material are both gradient-distributed along the α”-phase → β-phase direction. The content of precipitated phases in the microstructure of the material changes continuously along a preset direction, and the elastic modulus of the material changes continuously along a preset direction; wherein, the preset direction is upward along the bottom plate, α” phase → β phase; In the precipitated phase, the content of the α” phase changes monotonically along a preset direction, and the maximum volume fraction of the α” phase is 50%. In the precipitated phase, the β phase content changes monotonically along a preset direction; The elastic modulus ranges from 40 to 80 GPa, with a maximum difference of 35 GPa. The titanium-niobium alloy dual-gradient material is prepared by integral molding using electron beam additive manufacturing technology, specifically including the following steps: Step 1: Prepare an alloy package, controlling the mass percentage of Nb in the alloy composition to be 23%~26%, the mass fraction of O to be 0.1%~0.6%, with the balance being Ti, and perform vacuum melting; Step 2: Hot rolling and billet preparation, with billet temperature controlled at 700~1200℃ and billet deformation controlled at 10~50%; Step 3: Rolling deformation, controlling the rolling temperature at 300~700℃, and the rolling reduction at 10~50%; Step 4: Cooling, controlling the cooling rate at 10~30℃ / minute; cool to room temperature; Step 5; Aging: Perform room temperature aging treatment for 1-2 days to obtain titanium-niobium alloy. Step 6: Prepare titanium-niobium alloy spherical powder using the titanium-niobium alloy obtained in Step 5; Step 7: Design the gradient model and import the model into the electron beam control equipment control system; Step 8: Set process parameters; Step 9: Perform pre-printing processing. Rotate the support column to adjust the printing direction and height, and adjust the base plate to be level. Adjust the amount of powder picked up by the powder collector in a single pass until snowflake patterns appear evenly on the surface of the base plate. Adjust the powder picking amount so that the time for the powder collector to pass through the powder flow sensor is 150ms-180ms. Step 10: After reaching the predetermined state, start printing. During the printing process, adjust the process parameters according to the gradient model. Step 11: After printing is complete, inert gas is introduced for protection; In step 8, the initial printing plate temperature is 450-600℃; The preheating process parameters of the α-rich phase region are: a beam current of 18-20 mA; a scanning speed of 8000-12000 mm / s; and a scanning number of 14-16 times; and the printing process parameters of the α-rich phase region have an energy density of 45-55 J / mm 3 . The preheating process parameters of the β-rich phase region are: a beam current of 15-18 mA; a scanning speed of 12000-15000 mm / s; and a scanning number of 10-14 times; and the printing process parameters of the β-rich phase region have an energy density of 35-45 J / mm 3 . In step 10, after the α-rich phase region is printed, the process is switched to the β-rich phase region process to print the transition phase region and the β-rich phase region.

2. The method for preparing a titanium-niobium alloy dual-gradient material as described in claim 1.

3. The method for preparing a titanium-niobium alloy dual-gradient material according to claim 2, characterized in that, In step 6, the preparation method is either gas atomization or a rotating electrode; the powder particle size distribution range is 46μm to 106μm, and the particle size distribution must meet the following requirements: D10 is 45-50μm, D50 is 70-80μm, and D90 is 95-110μm; the loose packing density is 2.8-3.0g / cm³. 3 The tap density is 3.2-3.4 g / cm³. 3 The hollow pasta content shall not exceed 0.5%.

4. The method for preparing a titanium-niobium alloy dual-gradient material according to claim 2, characterized in that, In step 7, the gradient direction of the gradient material model must be consistent with the printing direction.

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