A method for additive manufacturing of a Ti2AlNb alloy with high strength and high plasticity

Abstract

The application discloses a kind of high-strength high-plasticity Ti2AlNb alloy additive preparation methods, comprising the following steps: one, setting scanning parameter;Two, prefabricated entity sheet layer;Three, in-situ heat treatment;Four, preparation component.The application is processed by slicing layering, using sheet layer alternation merging melting scanning mode, effectively avoid adjacent sheet layer overheating remelting, substantially increase the stability of organization and mechanical properties;Through in-situ heat treatment, it is beneficial to play the effect of phase boundary strengthening and solid solution strengthening, can improve the metallurgical bonding strength of sheet layer, solve the difference in structure and performance caused by sheet layer remelting, significantly improve its plasticity under the premise of maintaining the excellent strength of Ti2AlNb material, the tensile strength of prepared Ti2AlNb alloy is not less than 1100MPa, yield strength is not less than 990MPa, plasticity is not less than 6%, has wide application prospect in aerospace equipment field.

Description

Technical Field

[0001] This invention belongs to the field of metal additive manufacturing technology, specifically relating to a method for preparing Ti2AlNb alloy additives that combines high strength and high plasticity. Background Technology

[0002] Ti2AlNb alloy has only half the density of nickel-based superalloys, giving it a significant advantage in weight reduction for hot-end components of aircraft engines. It is a highly promising lightweight high-temperature structural material. However, due to the complex and varied shapes of aerospace parts, traditional casting processes for manufacturing brittle Ti2AlNb materials face high technical barriers and low yields, making it difficult to meet the needs of high-end aerospace equipment.

[0003] Additive manufacturing technology is a highly efficient and low-cost manufacturing technology that creates near-net-shape components by adding and stacking materials layer by layer. It breaks through the limitations of traditional manufacturing technologies on structural size and complexity, providing a revolutionary new technological approach for the manufacturing of large, complex, lightweight integral structures made of Ti2AlNb alloys. This technology is expected to promote the application and development of large-size Ti2AlNb alloys in next-generation high-performance aero-engines. However, existing additive manufacturing techniques for Ti2AlNb alloys suffer from poor formability, low room-temperature strength, and poor plasticity, significantly limiting the full potential of aerospace equipment. Simply adjusting the scanning current and scanning speed parameters of the additive manufacturing process is insufficient to simultaneously improve the strength and plasticity of Ti2AlNb alloys, failing to meet the application requirements of Ti2AlNb alloy additive-manufactured components.

[0004] The invention disclosed in CN119057079A proposes a laser melting deposition additive manufacturing method for Ti2AlNb alloy. This method mainly employs an interlayer pause printing method, during which the temperature of the printed alloy drops rapidly, effectively reducing the alloy's oxidation tendency. However, the room temperature strength of the billet is below 910 MPa, and the plasticity is below 3.5%.

[0005] The invention disclosed in publication number CN118977013A proposes a Ti2AlNb-based alloy wire, its preparation method, and its application in arc additive manufacturing. This method mainly involves adding boron (B) and high-density ta (Ta) to the composition of a Ti2AlNb-based alloy. However, the addition of B produces brittle precipitates that are prone to segregation, leading to unstable alloy microstructure and properties, and low material yield. The addition of high-density Ta significantly increases the alloy density, which does not meet the requirements for lightweight materials in aerospace components, making it inconvenient for production applications.

[0006] Therefore, there is a need to provide a method for additive manufacturing of Ti2AlNb alloys that combines high strength and high plasticity. Summary of the Invention

[0007] The technical problem to be solved by this invention is to provide an additive manufacturing method for Ti2AlNb alloys that combines high strength and high plasticity, addressing the shortcomings of the prior art. This method employs a layer-by-layer processing technique, effectively avoiding overheating and remelting of adjacent layers, significantly increasing microstructural stability and room-temperature mechanical properties. In-situ heat treatment enables efficient utilization of latent heat of fusion, greatly enhancing the metallurgical bonding strength of the layers. This solves the problem of microstructural and property differences caused by remelting of Ti2AlNb alloys, improving its strength while maintaining the excellent plasticity of Ti2AlNb material, and overcoming the difficulties of low room-temperature strength and poor plasticity in existing additive manufacturing methods for Ti2AlNb alloys.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for additive manufacturing of Ti2AlNb alloys with both high strength and high plasticity, characterized in that the method includes the following steps:

[0009] Step 1: Set scan parameters:

[0010] A 3D CAD model of the target product is established, and the model is divided into preset layers of equal thickness along its height direction to obtain preset layer data. The preset layer data is then processed into layers to obtain layered scanning data. The layered scanning data is then imported into an additive manufacturing equipment, and additive manufacturing parameters and in-situ heat treatment parameters are set to obtain an additive manufacturing equipment with parameters. The layering process is as follows: along the height direction of the 3D CAD model from bottom to top, the preset layers with odd numbers are arranged as single-level, and the preset layers with even numbers are arranged as double-level, with single-level and double-level alternating vertically.

[0011] Step 2: Prefabricate solid layers:

[0012] Ti2AlNb powder is loaded into the powder hopper of the additive manufacturing equipment with parameters obtained in step one, and after vacuuming, it is filled with inert gas. Then, Ti2AlNb powder is evenly spread on the upper surface of a stainless steel substrate. Then, the electron beam emitter is activated, and the spread Ti2AlNb powder is heated to complete melting according to the additive manufacturing parameters set in step one. After natural cooling, a pre-fabricated solid sheet is obtained. The thickness of the spread Ti2AlNb powder layer is the same as the thickness of the preset sheet in step one.

[0013] Step 3: In-situ heat treatment:

[0014] The electron beam emitter is activated, and the prefabricated solid sheet obtained in step two is subjected to in-situ heat treatment according to the in-situ heat treatment parameters set in step one. After natural cooling, the in-situ heat-treated solid sheet is obtained. The in-situ heat treatment is: the same prefabricated solid sheet is repeatedly scanned with an electron beam, and the scanning path is serpentine or parallel lines.

[0015] Step 4: Preparing the components:

[0016] Steps two to three are repeated sequentially: spreading Ti2AlNb powder, melting, cooling, in-situ heat treatment, and natural cooling, until each in-situ heat-treated solid sheet is stacked and deposited to obtain a prefabricated component. Then, the prefabricated component is furnace-cooled to room temperature and separated from the stainless steel substrate to obtain a Ti2AlNb alloy. The Ti2AlNb alloy has a room temperature tensile strength of not less than 1100 MPa, a yield strength of not less than 990 MPa, and a plasticity of not less than 6%.

[0017] This invention performs layered processing on the preset sheet data of the target product. By alternating single-level and double-level melting scans, it effectively avoids overheating and remelting of adjacent solid sheets, significantly increases the stability of the structure and mechanical properties, enables efficient utilization of latent heat of fusion, solves the differences in structure and properties caused by sheet remelting, improves the metallurgical bonding strength of adjacent layers, effectively enhances the room temperature strength and plasticity of components, reduces the risk of material failure, and improves forming efficiency and powder utilization.

[0018] This invention, without preheating the substrate, uses computer-controlled optimization of electron beam scanning line length, electron beam scanning speed, and electron beam scanning current to efficiently melt the powder in the scanning area. In-situ heat treatment optimizes the microstructure and properties of the component, resulting in a Ti2AlNb material with uniform internal grains and excellent mechanical properties. This allows for the integrated fabrication of Ti2AlNb alloy components with complex external structures, effectively strengthening the Ti2AlNb alloy, significantly improving production efficiency, reducing costs, and enhancing the mechanical properties of the Ti2AlNb alloy.

[0019] In summary, this invention effectively avoids overheating and remelting of adjacent layers through slicing and layering, significantly improving microstructure stability and room temperature mechanical properties. In-situ heat treatment enables efficient utilization of latent heat of fusion, greatly enhancing the metallurgical bonding strength of the layers. It solves the microstructure and property differences caused by remelting of Ti2AlNb alloy, improving its strength while maintaining the excellent plasticity of Ti2AlNb material. By controlling the powder spreading layer thickness, electron beam scanning speed, electron beam scanning line length, and electron beam scanning current, all factors work together on the Ti2AlNb alloy powder to ensure that the prepared Ti2AlNb alloy material has excellent room temperature strength and plasticity.

[0020] The above-mentioned additive manufacturing method for a high-strength and high-plasticity Ti2AlNb alloy is characterized in that the additive manufacturing equipment in step one is a powder bed electron beam additive manufacturing equipment; the Ti2AlNb powder is composed of the following mass percentages: Al 9.9%~11.9%, Nb 41.6%~43.6%, with the balance being Ti and other unavoidable impurities; the Ti2AlNb alloy powder has a particle size of no more than 120 μm and a particle size D50 =70μm~80μm, loose packing density greater than 3.2g / cm³ 3 This invention controls the parameters of Ti2AlNb powder to meet the process requirements of powder bed electron beam additive manufacturing, avoiding poor melting and inability to guarantee density due to excessively coarse powder, as well as affecting its spreading and flowability, resulting in process instability during the forming process.

[0021] The above-mentioned additive manufacturing method for a high-strength and high-plasticity Ti2AlNb alloy is characterized in that the thickness of the preset sheet in step one is 50μm~80μm. This invention, by dividing the three-dimensional CAD model of the target Ti2AlNb alloy into preset sheets of equal thickness (50μm~80μm) along the height direction, facilitates a uniform temperature field distribution during additive manufacturing. Furthermore, combined with the Ti2AlNb powder used, it prevents the problems of excessively small sheets leading to low additive manufacturing efficiency, and excessively thick sheets resulting in insufficient melting and unsatisfactory mechanical properties of the Ti2AlNb alloy.

[0022] The above-mentioned additive manufacturing method for a high-strength and high-plasticity Ti2AlNb alloy is characterized in that the additive manufacturing parameters in step one include: a single-stage electron beam scanning line length of 2.5mm~5.5mm, an electron beam scanning speed of 1.2m / s~3m / s, and an electron beam scanning current of 2.5mA~5.8mA; and a two-stage electron beam scanning line length of 6.5mm~8.5mm, an electron beam scanning speed of 3.2m / s~5.5m / s, and an electron beam scanning current of 2.5mA~5.8mA. The preferred single-stage electron beam scanning line length of this invention is 2.5 mm to 5.5 mm, which helps to reduce the heat-affected zone, reduce thermal stress concentration and cracking tendency, improve the dimensional accuracy and surface quality of the Ti2AlNb alloy product, and enhance the mechanical properties of the product. The preferred single-stage electron beam scanning speed is 1.2 m / s to 3 m / s, which is beneficial for melting the Ti2AlNb alloy powder and achieving a fine microstructure and uniform temperature gradient. The preferred single-stage electron beam scanning current is 2.5 mA to 5.8 mA, which helps to reduce the heat-affected zone, reduce thermal stress concentration and cracking tendency. The preferred dual-stage electron beam scanning line length is 6.5 mm to 8.5 mm. The preferred dual-stage electron beam scanning speed of 3.2m / s to 5.5m / s is beneficial for melting Ti2AlNb alloy powder, increasing the microstructure stability and room temperature mechanical properties of the Ti2AlNb alloy. The preferred dual-stage electron beam scanning current of 2.5mA to 5.8mA enables efficient utilization of latent heat of fusion, solves the microstructure and property differences caused by remelting, improves the metallurgical bonding strength between adjacent layers, effectively enhances the room temperature mechanical properties of the component, and reduces the risk of material failure.

[0023] The above-mentioned additive manufacturing method for a high-strength and high-ductility Ti2AlNb alloy is characterized by the following in-situ heat treatment parameters in step one: electron beam scanning line length of 2.5mm~8.5mm, electron beam scanning speed of 8m / s~35m / s, and electron beam scanning current of 30mA~60mA. Preferred in-situ heat treatment parameters include: an electron beam scanning line length of 2.5mm~8.5mm, which helps improve the metallurgical bonding strength of the lamellar layers, thus enhancing both strength and ductility; an electron beam scanning speed of 8m / s~35m / s, which promotes a uniform temperature field distribution and improves the room temperature strength and ductility of the resulting Ti2AlNb alloy; and an electron beam scanning current of 30mA~60mA, which enables efficient utilization of latent heat of fusion, preventing overheating and remelting of adjacent solid lamellar layers.

[0024] The above-mentioned additive manufacturing method for a Ti2AlNb alloy exhibiting both high strength and high plasticity is characterized in that, in step two, the vacuum level is not lower than 1.2 × 10⁻⁶. -3 Pa; the inert gas is helium. This invention, by using helium as the inert protective atmosphere, helps to avoid the formation of brittle inclusions due to gas ionization at high energies, thus preventing a decrease in the strength and plasticity of the component.

[0025] The above-mentioned additive manufacturing method for a high-strength and high-plasticity Ti2AlNb alloy is characterized in that the in-situ heat treatment in step three is annealing or aging treatment, with a temperature of 700℃~800℃ and a time of 1min~3min; the lamellar depth of the in-situ heat treatment should be controlled within 50μm~80μm. Preferably, the in-situ heat treatment of this invention is annealing or aging treatment, with a temperature of 700℃~800℃ and a time of 1min~3min, and the heat treatment depth should be controlled within 50μm~80μm. This ensures that the heat treatment temperature and time are appropriate and form a good metallurgical bond, preventing insufficient heating of the lamellars due to excessively low heat treatment temperature or time, and avoiding insufficient heat treatment depth, which would result in the Ti2AlNb alloy failing to meet mechanical strength requirements. It also prevents excessively high heat treatment temperature or time, and avoids excessively shallow heat treatment depth, which would result in overheating of the lamellars, coarse grains, and a decrease in the strength and plasticity of the Ti2AlNb alloy.

[0026] The above-mentioned additive manufacturing method for a Ti2AlNb alloy with both high strength and high plasticity is characterized in that the Ti2AlNb alloy in step three is applied to aerospace thin-walled structural parts.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] 1. This invention performs layered processing on the preset sheet data and uses a single-level and double-level alternating merging melting scanning method to effectively avoid overheating and remelting of adjacent solid sheets, greatly improve the structural stability and room temperature mechanical properties, solve the structural and property differences caused by remelting in the sheet bonding area, and significantly improve the metallurgical bonding strength of adjacent sheets.

[0029] 2. This invention utilizes optimized electron beam additive manufacturing parameters applied to Ti2AlNb alloy powder, fully leveraging the non-equilibrium chemical metallurgical reaction of electron beam melting of powder, effectively improving the mechanical properties of Ti2AlNb alloy and complex components, obtaining a Ti2AlNb alloy with both high strength and high plasticity, realizing a low-cost, high-structure stability, and high-efficiency near-net-shape forming process, with high material utilization and fast manufacturing speed.

[0030] 3. The additive manufacturing process of this invention does not use substrate preheating, which reduces the risk of overheating and remelting of the laminations and is beneficial to improving the stability of the alloy structure and mechanical properties. Through in-situ heat treatment, the latent heat of fusion can be efficiently utilized, effectively increasing the stability of the structure and giving full play to the effects of phase boundary strengthening and solid solution strengthening. While maintaining the excellent strength of Ti2AlNb material, the room temperature plasticity is increased to 1.2 to 3 times the original level.

[0031] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0032] Figure 1 This is an optical microstructure image of the Ti2AlNb alloy prepared in Example 1 of the present invention.

[0033] Figure 2 This is an optical microstructure diagram of the Ti2AlNb alloy prepared in Comparative Example 1 of this invention.

[0034] Figure 3 This is an optical microstructure diagram of the Ti2AlNb alloy prepared in Comparative Example 2 of this invention. Detailed Implementation

[0035] Example 1

[0036] This embodiment includes the following steps:

[0037] Step 1: Set scan parameters:

[0038] A 3D CAD model of the target product is established, and the model is divided into pre-defined layers of equal thickness along its height direction to obtain pre-defined layer data. This pre-defined layer data is then processed into layered scanning data. The layered scanning data is then imported into an additive manufacturing equipment, and additive manufacturing parameters and in-situ heat treatment parameters are set to obtain an additive manufacturing equipment with parameters. The layering process involves arranging the odd-numbered pre-defined layers as single-level and the even-numbered pre-defined layers as double-level along the height direction of the 3D CAD model from bottom to top, with single-level and double-level alternating vertically. The Ti2AlNb powder is composed of the following mass percentages: Al 9.9%, Nb 43.6%, with the balance being Ti and other unavoidable impurities. The Ti2AlNb alloy powder has a particle size of 35μm~120μm and a particle size D... 50 =70μm, loose powder density is 3.5g / cm³ 3 The preset layer thickness is 50 μm; the set additive manufacturing parameters include: a single-stage electron beam scanning line length of 2.5 mm, an electron beam scanning speed of 1.2 m / s, and an electron beam scanning current of 2.5 mA; a two-stage electron beam scanning line length of 6.5 mm, an electron beam scanning speed of 3.2 m / s, and an electron beam scanning current of 2.5 mA; the set in-situ heat treatment parameters include: an electron beam scanning line length of 2.5 mm, an electron beam scanning speed of 8 m / s, and an electron beam scanning current of 30 mA.

[0039] Step 2: Prefabricate solid layers:

[0040] Ti2AlNb powder is loaded into the powder hopper of the additive manufacturing equipment with parameters obtained in step one, and after evacuation, it is filled with inert gas. Then, Ti2AlNb powder is evenly spread on the upper surface of a stainless steel substrate. The electron beam emitter is then activated, and the spread Ti2AlNb powder is heated to complete melting according to the additive manufacturing parameters set in step one. After natural cooling, a pre-fabricated solid sheet is obtained. The thickness of the spread Ti2AlNb powder layer is the same as the preset sheet thickness in step one. The vacuum level is 1.2 × 10⁻⁶. -3 Pa; the inert gas is commercially available high-purity helium;

[0041] Step 3: In-situ heat treatment:

[0042] The electron beam emitter is activated, and the prefabricated solid sheet obtained in step two is subjected to in-situ heat treatment according to the in-situ heat treatment parameters set in step one. After natural cooling, the in-situ heat-treated solid sheet is obtained. The in-situ heat treatment is: repeated scanning of the same prefabricated solid sheet using an electron beam, with the scanning path being serpentine or parallel lines. The in-situ heat treatment is annealing: the temperature is 700℃, the time is 1 min, and the heat-treated sheet depth is 50 μm.

[0043] Step 4: Preparing the components:

[0044] The process of spreading Ti2AlNb powder, melting, cooling, in-situ heat treatment, and natural cooling in steps two to three is repeated sequentially until the solid layers after each in-situ heat treatment are stacked and deposited to obtain a prefabricated component. Then, the prefabricated component is furnace cooled to room temperature and separated from the stainless steel substrate to obtain the Ti2AlNb alloy.

[0045] Figure 1 This is an optical microstructure image of the Ti2AlNb alloy prepared in this embodiment, as shown below. Figure 1 As shown, the Ti2AlNb alloy prepared in this embodiment has no unmelted powder, no pores, excellent metallurgical bonding, and a dense and highly uniform structure, which is beneficial to improving the stability and mechanical properties of the alloy structure.

[0046] The Ti2AlNb alloy prepared in this embodiment has a room temperature tensile strength of 1130 MPa, a yield strength of 991%, and a plasticity of 6%, as tested.

[0047] Comparative Example 1

[0048] The difference between this comparative example and Example 1 is that no layering process was performed in step one, and the additive manufacturing parameters include: electron beam scanning line length of 2.5 mm, electron beam scanning speed of 1.2 m / s, and electron beam scanning current of 2.5 mA.

[0049] Figure 2 The optical microstructure of the Ti2AlNb alloy prepared in this comparative example is shown in the figure. Figure 2 As shown, the Ti2AlNb alloy prepared in this comparative example has obvious pores, low microstructure uniformity, poor metallurgical bonding, and is not conducive to improving the stability and mechanical properties of the alloy structure.

[0050] The Ti2AlNb alloy prepared in this comparative example has a room temperature tensile strength of 862 MPa, a yield strength of 709 MPa, and a plasticity of 2.5%.

[0051] Based on this comparative example and Example 1, it is shown that the absence of gradation of the lamellar layers and the lack of alternating merging and melting scanning of the lamellar layers will cause overheating and remelting of adjacent single-layer solid lamellar layers, reducing the metallurgical bonding strength of adjacent layers, significantly reducing the stability of the microstructure and high-temperature mechanical properties, which is not conducive to improving the temperature resistance of Ti2AlNb alloy and increasing the risk of material failure.

[0052] Comparative Example 2

[0053] The difference between this comparative example and Example 1 is that no in-situ heat treatment was performed in step three.

[0054] Figure 3 The optical microstructure of the Ti2AlNb alloy prepared in this comparative example is shown in the figure. Figure 3 As shown, the Ti2AlNb alloy prepared in this comparative example exhibits obvious internal porosity, low microstructure uniformity, poor metallurgical bonding, and low high-temperature microstructure stability. Testing revealed that the tensile strength of the Ti2AlNb alloy prepared in this comparative example is 620 MPa, the yield strength is 350 MPa, and the plasticity is 3.5%.

[0055] Based on this comparative example and Example 1, it is shown that the absence of in-situ heat treatment reduces the metallurgical bond strength between adjacent layers, reduces the strength and plasticity of the alloy, and increases the risk of material failure.

[0056] Example 2

[0057] This embodiment includes the following steps:

[0058] Step 1: Set scan parameters:

[0059] A 3D CAD model of the target product is established, and the model is divided into pre-defined layers of equal thickness along its height direction to obtain pre-defined layer data. This pre-defined layer data is then processed into layered scanning data. The layered scanning data is then imported into an additive manufacturing equipment, and additive manufacturing parameters and in-situ heat treatment parameters are set to obtain an additive manufacturing equipment with parameters. The layering process involves arranging the odd-numbered pre-defined layers as single-level and the even-numbered pre-defined layers as double-level along the height direction of the 3D CAD model from bottom to top, with single-level and double-level alternating vertically. The Ti2AlNb powder is composed of the following mass percentages: Al 10.5%, Nb 42.5%, with the balance being Ti and other unavoidable impurities. The Ti2AlNb alloy powder has a particle size of 35μm~120μm and a particle size D... 50 =75μm, loose powder density is 3.5g / cm³ 3 The preset layer thickness is 60 μm; the set additive manufacturing parameters include: a single-stage electron beam scanning line length of 3.5 mm, an electron beam scanning speed of 2.5 m / s, and an electron beam scanning current of 4.8 mA; a two-stage electron beam scanning line length of 7.5 mm, an electron beam scanning speed of 4.5 m / s, and an electron beam scanning current of 3.8 mA; the set in-situ heat treatment parameters include: an electron beam scanning line length of 6.5 mm, an electron beam scanning speed of 15 m / s, and an electron beam scanning current of 40 mA.

[0060] Step 2: Prefabricate solid layers:

[0061] Ti2AlNb powder is loaded into the powder hopper of the additive manufacturing equipment with parameters obtained in step one, and after evacuation, it is filled with inert gas. Then, Ti2AlNb powder is evenly spread on the upper surface of a stainless steel substrate. The electron beam emitter is then activated, and the spread Ti2AlNb powder is heated to complete melting according to the additive manufacturing parameters set in step one. After natural cooling, a pre-fabricated solid sheet is obtained. The thickness of the spread Ti2AlNb powder layer is the same as the preset sheet thickness in step one. The vacuum level is 1.2 × 10⁻⁶. -3 Pa; the inert gas is commercially available high-purity helium;

[0062] Step 3: In-situ heat treatment:

[0063] The electron beam emitter is activated, and the prefabricated solid sheet obtained in step two is subjected to in-situ heat treatment according to the in-situ heat treatment parameters set in step one. After natural cooling, the in-situ heat-treated solid sheet is obtained. The in-situ heat treatment is: repeated scanning of the same prefabricated solid sheet using an electron beam, with the scanning path being serpentine or parallel lines. The in-situ heat treatment is annealing: the temperature is 750℃, the time is 2 min, and the heat treatment depth is 60 μm.

[0064] Step 4: Preparing the components:

[0065] The process of spreading Ti2AlNb powder, melting, cooling, in-situ heat treatment, and natural cooling in steps two to three is repeated sequentially until the solid layers after each in-situ heat treatment are stacked and deposited to obtain a prefabricated component. Then, the prefabricated component is furnace cooled to room temperature and separated from the stainless steel substrate to obtain the Ti2AlNb alloy.

[0066] Testing revealed that the Ti2AlNb alloy prepared in this embodiment is internally dense and defect-free, has high metallurgical bonding, a dense and uniform microstructure, and excellent high-temperature microstructure stability. The room temperature tensile strength is 1100 MPa, the yield strength is 992 MPa, and the plasticity is 10%.

[0067] Example 3

[0068] This embodiment includes the following steps:

[0069] Step 1: Set scan parameters:

[0070] A 3D CAD model of the target product is established, and the model is divided into pre-defined layers of equal thickness along its height direction to obtain pre-defined layer data. This pre-defined layer data is then processed into layered scanning data. The layered scanning data is then imported into an additive manufacturing equipment, and additive manufacturing parameters and in-situ heat treatment parameters are set to obtain an additive manufacturing equipment with parameters. The layering process involves arranging the odd-numbered pre-defined layers as single-level and the even-numbered pre-defined layers as double-level along the height direction of the 3D CAD model from bottom to top, with single-level and double-level alternating vertically. The Ti2AlNb powder is composed of the following mass percentages: Al 11.9%, Nb 41.6%, with the balance being Ti and other unavoidable impurities. The Ti2AlNb alloy powder has a particle size of 35μm~120μm and a particle size D... 50 =80μm, loose powder density is 3.5g / cm³ 3 The preset layer thickness is 80 μm; the set additive manufacturing parameters include: a single-stage electron beam scanning line length of 5.5 mm, an electron beam scanning speed of 3 m / s, and an electron beam scanning current of 5.8 mA; a two-stage electron beam scanning line length of 8.5 mm, an electron beam scanning speed of 5.5 m / s, and an electron beam scanning current of 5.8 mA; the set in-situ heat treatment parameters include: an electron beam scanning line length of 8.5 mm, an electron beam scanning speed of 35 m / s, and an electron beam scanning current of 60 mA.

[0071] Step 2: Prefabricate solid layers:

[0072] Ti2AlNb powder is loaded into the powder hopper of the additive manufacturing equipment with parameters obtained in step one, and after evacuation, it is filled with inert gas. Then, Ti2AlNb powder is evenly spread on the upper surface of a stainless steel substrate. The electron beam emitter is then activated, and the spread Ti2AlNb powder is heated to complete melting according to the additive manufacturing parameters set in step one. After natural cooling, a pre-fabricated solid sheet is obtained. The thickness of the spread Ti2AlNb powder layer is the same as the preset sheet thickness in step one. The vacuum level is 1.2 × 10⁻⁶. -3 Pa; the inert gas is commercially available high-purity helium;

[0073] Step 3: In-situ heat treatment:

[0074] The electron beam emitter is activated, and the prefabricated solid sheet obtained in step two is subjected to in-situ heat treatment according to the in-situ heat treatment parameters set in step one. After natural cooling, the in-situ heat-treated solid sheet is obtained. The in-situ heat treatment is: repeated scanning of the same prefabricated solid sheet using an electron beam, with the scanning path being serpentine or parallel lines. The in-situ heat treatment is an aging treatment: the temperature is 800℃, the time is 3min, and the sheet depth is 80μm.

[0075] Step 4: Preparing the components:

[0076] The process of spreading Ti2AlNb powder, melting, cooling, in-situ heat treatment, and natural cooling in steps two to three is repeated sequentially until the solid layers after each in-situ heat treatment are stacked and deposited to obtain a prefabricated component. Then, the prefabricated component is furnace cooled to room temperature and separated from the stainless steel substrate to obtain the Ti2AlNb alloy.

[0077] Testing revealed that the Ti2AlNb alloy prepared in this embodiment is internally dense and defect-free, exhibits excellent metallurgical bonding, and possesses a dense and highly uniform microstructure, which is beneficial for improving strength and plasticity. The room temperature tensile strength is 1230 MPa, the yield strength is 1100 MPa, and the plasticity is 10%.

[0078] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for additive manufacturing of Ti2AlNb alloys with both high strength and high plasticity, characterized in that, The method includes the following steps: Step 1: Set scan parameters: A 3D CAD model of the target product is established, and the model is divided into preset layers of equal thickness along its height direction to obtain preset layer data. This preset layer data is then processed into layered scanning data. The layered scanning data is then imported into an additive manufacturing equipment, and additive manufacturing parameters and in-situ heat treatment parameters are set to obtain an additive manufacturing equipment with parameters. The layering process involves arranging the preset layers with odd numbers of layers as single-level and even numbers as double-level along the height direction of the 3D CAD model from bottom to top, with single-level and double-level layers alternating vertically. The additive manufacturing parameters include: for single-level layers, the electron beam scanning line length is 2.5mm~5.5mm, the electron beam scanning speed is 1.2m / s~3m / s, and the electron beam scanning current is 2.5mA~5.8mA; for double-level layers, the electron beam scanning line length is 6.5mm~8.5mm, the electron beam scanning speed is 3.2m / s~5.5m / s, and the electron beam scanning current is 2.5mA~5.8mA. Step 2: Prefabricate solid layers: Ti2AlNb powder is loaded into the powder hopper of the additive manufacturing equipment with parameters obtained in step one, and after vacuuming, it is filled with inert gas. Then, Ti2AlNb powder is evenly spread on the upper surface of a stainless steel substrate. Then, the electron beam emitter is activated, and the spread Ti2AlNb powder is heated to complete melting according to the additive manufacturing parameters set in step one. After natural cooling, a pre-fabricated solid sheet is obtained. The thickness of the spread Ti2AlNb powder layer is the same as the thickness of the preset sheet in step one. Step 3: In-situ heat treatment: The electron beam emitter is activated, and the prefabricated solid sheet obtained in step two is subjected to in-situ heat treatment according to the in-situ heat treatment parameters set in step one. After natural cooling, the in-situ heat-treated solid sheet is obtained. The in-situ heat treatment is: the same prefabricated solid sheet is repeatedly scanned with an electron beam, and the scanning path is serpentine or parallel lines. Step 4: Component preparation Steps two to three are repeated sequentially: spreading Ti2AlNb powder, melting, cooling, in-situ heat treatment, and natural cooling, until each in-situ heat-treated solid sheet is stacked and deposited to obtain a prefabricated component. Then, the prefabricated component is furnace-cooled to room temperature and separated from the stainless steel substrate to obtain a Ti2AlNb alloy. The Ti2AlNb alloy has a room temperature tensile strength of not less than 1100 MPa, a yield strength of not less than 990 MPa, and a plasticity of not less than 6%.

2. The additive manufacturing method for a high-strength and high-plasticity Ti2AlNb alloy according to claim 1, characterized in that, The additive manufacturing equipment mentioned in step one is a powder bed electron beam additive manufacturing equipment; the Ti2AlNb powder is composed of the following mass percentages: Al 9.9%~11.9%, Nb 41.6%~43.6%, with the balance being Ti and other unavoidable impurities; the Ti2AlNb alloy powder has a particle size of no more than 120μm and a particle size D. 50 =70μm~80μm, loose packing density greater than 3.2g / cm³ 3 .

3. The additive manufacturing method for a high-strength and high-plasticity Ti2AlNb alloy according to claim 1, characterized in that, The thickness of the preset sheet in step one is 50μm~80μm.

4. The additive manufacturing method for a high-strength and high-plasticity Ti2AlNb alloy according to claim 1, characterized in that, The in-situ heat treatment parameters mentioned in step one include: electron beam scanning line length of 2.5mm~8.5mm, electron beam scanning speed of 8m / s~35m / s, and electron beam scanning current of 30mA~60mA.

5. The additive manufacturing method for a high-strength and high-plasticity Ti2AlNb alloy according to claim 1, characterized in that, Step two involves evacuating the vacuum to a level not lower than 1.2 × 10⁻⁶. -3 Pa; the inert gas is helium.

6. The additive manufacturing method for a high-strength and high-plasticity Ti2AlNb alloy according to claim 1, characterized in that, The in-situ heat treatment in step three is annealing or aging treatment, with a temperature of 700℃~800℃ and a time of 1min~3min; the lamellar depth of the in-situ heat treatment is controlled at 50μm~80μm.

7. The additive manufacturing method for a high-strength and high-plasticity Ti2AlNb alloy according to claim 1, characterized in that, The Ti2AlNb alloy described in step three is used in aerospace thin-walled structural components.

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