Additive preparation method of Ti2AlNb alloy with high strength and high plasticity

Abstract

The invention discloses a high-strength and high-plasticity Ti2AlNb alloy additive preparation method. The high-strength and high-plasticity Ti2AlNb alloy additive preparation method comprises the following steps that firstly, scanning parameters are set; 2, prefabricating a solid sheet layer; 3, in-situ heat treatment; and 4, preparing the component. According to the preparation method, through slicing and layering treatment, by means of a slice layer alternate merging melting scanning mode, overheating and remelting of adjacent slice layers are effectively avoided, and the structure stability and the mechanical property are greatly improved; the in-situ heat treatment is beneficial to exerting the effects of phase boundary strengthening and solid solution strengthening, the metallurgical bonding strength of lamellas can be improved, the structure and performance difference caused by lamellar remelting is solved, the plasticity of the Ti2AlNb alloy is remarkably improved on the premise that the excellent strength of the Ti2AlNb material is kept, the room-temperature tensile strength of the prepared Ti2AlNb alloy is not lower than 1100 MPa, the yield strength is not lower than 990MPa, and the tensile strength of the prepared Ti2AlNb alloy is not lower than 10MPa. The plasticity is not lower than 6%, and the method has a wide application prospect in the field of aerospace equipment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal additive manufacturing, and particularly relates to a method for additive manufacturing of Ti2AlNb alloy with high strength and high plasticity. BACKGROUND

[0002] Ti2AlNb alloy has a density only half of that of nickel-based high-temperature alloy, has great advantages in weight reduction of hot end parts of aircraft engines, and is a very potential lightweight high-temperature structural material. Due to the complex and variable shape of the aircraft parts, the traditional casting process method has problems such as high technical barriers, low yield rate and the like in manufacturing brittle Ti2AlNb material, and is difficult to meet the use requirements of high-end aviation industrial equipment.

[0003] Additive manufacturing technology is a high-efficiency and low-cost manufacturing technology for near-net forming of parts through layer-by-layer addition and layer-by-layer accumulation of materials, breaks through the limitations of traditional manufacturing technology on structure size and complexity, provides a revolutionary new way for the manufacturing of large-scale complex integral lightweight structures of Ti2AlNb alloy, and is expected to promote the application and development of large-size Ti2AlNb alloy in the new generation of high-performance aircraft engines. However, the existing additive manufacturing Ti2AlNb alloy forming process has poor processability, low room temperature strength and poor plasticity, which greatly limits the full play of the performance of aerospace equipment. It is difficult to realize the synchronous improvement of the strength and plasticity of Ti2AlNb alloy by adjusting the scanning current and scanning speed parameters of the additive manufacturing forming process, and the application requirements of the additive manufacturing components of Ti2AlNb alloy cannot be met.

[0004] The application with the publication number CN119057079A proposes a laser melting deposition additive manufacturing method of Ti2AlNb alloy. The method mainly adopts a layer-by-layer pause printing method, and the temperature of the printed alloy rapidly decreases in the pause process, which can effectively reduce the oxidation tendency of the alloy, but the room temperature strength of the blank is less than 910MPa, and the plasticity is less than 3.5%.

[0005] The application with the publication number CN118977013A proposes a Ti2AlNb-based alloy wire, a preparation method thereof and application thereof in electric arc additive manufacturing. The method mainly adds B element and high-density Ta element on the basis of the composition of Ti2AlNb-based alloy, but the addition of B element will produce brittle precipitated phase, and the precipitated phase is easy to segregate, resulting in unstable structure and performance of the alloy and low material yield rate; the addition of high-density Ta element will significantly increase the density of the alloy, which does not meet the use requirements of lightweight materials for aviation components, and is not convenient for production and application.

[0006] Therefore, it is necessary to provide a method for additive manufacturing of Ti2AlNb alloy with high strength and high plasticity. SUMMARY

[0007] The technical problem to be solved by the present application is to provide a Ti2AlNb alloy additive manufacturing method with high strength and high plasticity in view of the shortcomings of the prior art. The method adopts sheet layering processing, effectively avoids overheating and remelting of adjacent sheets, greatly increases the organizational stability and room temperature mechanical properties, and in-situ heat treatment can realize efficient utilization of melting latent heat, greatly improve the metallurgical bonding strength of the sheet, solve the difference in structure and performance caused by Ti2AlNb alloy remelting, improve the strength of Ti2AlNb material under the premise of maintaining excellent plasticity, and solve the problems of low room temperature strength and poor plasticity of existing additive manufacturing Ti2AlNb alloy.

[0008] To solve the above technical problems, the technical scheme adopted by the present application is: a Ti2AlNb alloy additive manufacturing method with high strength and high plasticity, characterized in that the method comprises the following steps: Step one, set scanning parameters: A three-dimensional CAD model of the target product is established, and the three-dimensional CAD model is divided into equal-thickness preset sheet layers along the height direction to obtain preset sheet layer data. Then, the preset sheet layer data is subjected to layering processing to obtain layering scanning data, which is then imported into the additive manufacturing equipment and the additive manufacturing parameters and in-situ heat treatment parameters are set to obtain the additive manufacturing equipment with parameters; the layering processing is as follows: along the height direction of the three-dimensional CAD model, the odd-numbered preset sheet layers are arranged as single stages, and the even-numbered preset sheet layers are arranged as double stages, and the single stages and double stages are arranged alternately in the longitudinal direction; Step two, preform solid sheet layer: The Ti2AlNb powder is loaded into the powder bin of the additive manufacturing equipment with parameters obtained in step one, and after vacuumizing, inert gas is filled. Then, the Ti2AlNb powder is uniformly spread on the upper surface of the stainless steel substrate, and then the electron beam emitter is started. The spread Ti2AlNb powder is heated to complete melting according to the additive manufacturing parameters set in step one, and the preform solid sheet layer is obtained after natural cooling; the thickness of the spread Ti2AlNb powder layer is the same as the thickness of the preset sheet layer in step one; Step three, in-situ heat treatment: The electron beam emitter is started, and the preform solid sheet layer obtained in step two is subjected to in-situ heat treatment according to the in-situ heat treatment parameters set in step one. The in-situ heat treated solid sheet layer is obtained after natural cooling; the in-situ heat treatment is as follows: the same preform solid sheet layer is repeatedly scanned by electron beam, and the scanning path is serpentine or parallel line; Step four, prepare the component: The steps of spreading Ti2AlNb powder, melting, cooling, in-situ heat treatment and natural cooling in steps two to three are repeated in turn until the solid layers after each in-situ heat treatment are deposited layer by layer to obtain a preform, then the preform is separated from the stainless steel substrate after furnace cooling to room temperature, and a Ti2AlNb alloy is obtained; the Ti2AlNb alloy has a tensile strength at room temperature of not less than 1100 MPa, a yield strength of not less than 990 MPa, and a plasticity of not less than 6%.

[0009] The preset layer data of the target product is subjected to layered processing in the application, and through single-stage and double-stage alternating combined melting scanning, overheating and remelting of adjacent solid layers are effectively avoided, the organizational stability and mechanical properties are greatly increased, efficient utilization of the latent heat of melting is realized, the differences in structure and performance caused by layer remelting are solved, the metallurgical bonding strength of adjacent layers is improved, the room temperature strength and plasticity of the component are effectively improved, the risk of material failure is reduced, and the forming efficiency and powder utilization rate are improved.

[0010] In the application, without preheating the substrate, only the powder in the scanning area is efficiently melted by combining computer control with preferred electron beam scanning line length, electron beam scanning speed and electron beam scanning current, the component structure and performance are optimized by in-situ heat treatment, a Ti2AlNb material with uniform internal grains and excellent mechanical properties is obtained, the integrated preparation of a Ti2AlNb alloy component with a complex shape structure is completed, the Ti2AlNb alloy can be effectively strengthened, the production efficiency is greatly improved, the cost is reduced, and the mechanical properties of the Ti2AlNb alloy are improved.

[0011] In summary, through slice layered processing, overheating and remelting of adjacent layers are effectively avoided, the organizational stability and room temperature mechanical properties are greatly increased, efficient utilization of the latent heat of melting is realized through in-situ heat treatment, the metallurgical bonding strength of the layers is greatly improved, the differences in structure and performance caused by Ti2AlNb alloy remelting are solved, the strength of the Ti2AlNb material is improved on the premise of maintaining excellent plasticity, the powder spreading layer thickness, electron beam scanning speed, electron beam scanning line length and electron beam scanning current are controlled to jointly act on the Ti2AlNb alloy powder, and the room temperature strength and plasticity of the prepared Ti2AlNb alloy material are excellent.

[0012] The additive manufacturing device in step one is a powder bed electron beam additive manufacturing device; the Ti2AlNb powder is composed of the following components by mass percentage: Al 9.9%~11.9%, Nb 41.6%~43.6%, and the balance is Ti element and other unavoidable impurities; the Ti2AlNb alloy powder has a particle size of not more than 120 μm, a particle size D 50=70μm~80μm, loose bulk density is greater than 3.2g / cm 3 The application controls the parameters of the Ti2AlNb powder to meet the process requirements of the powder bed electron beam additive manufacturing, avoids poor melting caused by too coarse powder, and affects the spreading and fluidity of the powder, causing process instability in the forming process.

[0013] The additive preparation method of the Ti2AlNb alloy with high strength and high plasticity has the characteristics that the preset slice layer thickness in step one is 50μm~80μm. The three-dimensional CAD model of the target product Ti2AlNb alloy is divided into 50μm~80μm equal-thickness preset slice layers along the height direction, which is beneficial to the uniform distribution of the temperature field in the additive manufacturing process, and the Ti2AlNb powder used prevents the additive manufacturing efficiency from being too low due to too small slice layers, and the mechanical properties of the product Ti2AlNb alloy cannot meet the requirements due to insufficient melting of too thick slice layers.

[0014] The additive preparation method of the Ti2AlNb alloy with high strength and high plasticity has the characteristics that the additive manufacturing parameters in step one include: the single-stage electron beam scanning line length is 2.5mm~5.5mm, the electron beam scanning speed is 1.2m / s~3m / s, the electron beam scanning current is 2.5mA~5.8mA, the double-stage 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. The preferred single-stage electron beam scanning line length is 2.5mm~5.5mm, which helps to reduce the heat affected zone, reduce thermal stress concentration and cracking tendency, improve the size accuracy and surface quality of the product Ti2AlNb alloy, and increase the mechanical properties of the product. The preferred single-stage electron beam scanning speed is 1.2m / s~3m / s, which is beneficial to melting the Ti2AlNb alloy powder and achieving fine microstructure and uniform temperature gradient. The preferred single-stage electron beam scanning current is 2.5mA~5.8mA, which helps to reduce the heat affected zone, reduce thermal stress concentration and cracking tendency. The preferred double-stage electron beam scanning line length is 6.5mm~8.5mm, which can shorten the preparation time, improve the production efficiency, and reduce the heat accumulation, which is beneficial to improving the room temperature strength and plasticity of the product Ti2AlNb alloy. The preferred double-stage electron beam scanning speed is 3.2m / s~5.5m / s, which is beneficial to melting the Ti2AlNb alloy powder, increasing the stability of the product Ti2AlNb alloy organization and the room temperature mechanical properties. The preferred double-stage electron beam scanning current is 2.5mA~5.8mA, which realizes efficient utilization of latent heat of melting, solves the difference in organization and performance caused by remelting, improves the metallurgical bonding strength of adjacent layers, effectively improves the room temperature mechanical properties of the component, and reduces the risk of material failure. The additive preparation method of the Ti2AlNb alloy with high strength and high plasticity has the characteristics that the in-situ heat treatment parameters in the step one include that the electron beam scanning line length is 2.5mm-8.5mm, the electron beam scanning speed is 8m / s-35m / s, and the electron beam scanning current is 30mA-60mA.

[0015] The additive preparation method of the Ti2AlNb alloy with high strength and high plasticity has the characteristics that in the step two, the vacuum degree is not less than 1.2*10 -3 Pa after vacuumizing, and the inert gas is helium.

[0016] The additive preparation method of the Ti2AlNb alloy with high strength and high plasticity has the characteristics that in the step three, the in-situ heat treatment is annealing or aging treatment, the temperature is 700-800℃, the time is 1-3min, and the lamella depth of the in-situ heat treatment is controlled to be 50-80um.

[0017] The additive preparation method of the Ti2AlNb alloy with high strength and high plasticity has the characteristics that in the step three, the Ti2AlNb alloy is applied to an aviation thin-wall structural member.

[0018] Compared with the prior art, the additive preparation method of the Ti2AlNb alloy with high strength and high plasticity has the following advantages: 1、The preset sheet data is processed in layers, and a single-stage and double-stage alternating combined melting scanning mode is used, so that overheating and remelting of adjacent solid sheets are effectively avoided, the organization stability and room temperature mechanical properties are greatly increased, the differences in organization and performance caused by remelting of the sheet joint area are solved, and the metallurgical bonding strength of adjacent sheets is greatly improved.

[0019] 2、The preferred electron beam additive manufacturing parameters are used on the Ti2AlNb alloy powder, the non-equilibrium chemical metallurgical reaction of the electron beam melting powder is fully utilized, the mechanical properties of the Ti2AlNb alloy and the complex component are effectively improved, the Ti2AlNb alloy with high strength and high plasticity is obtained, the low-cost, high-organization stability and high-efficiency near-net forming process is realized, the material utilization rate is high, and the manufacturing speed is fast.

[0020] 3、The additive manufacturing process of the application does not use substrate preheating, reduces the risk of sheet overheating and remelting, and is beneficial to improve the alloy organization stability and mechanical properties; through in-situ heat treatment, the latent heat of melting can be efficiently utilized, the organization stability is effectively increased, the effects of phase boundary strengthening and solid solution strengthening are fully utilized, the room temperature plasticity is improved to 1.2-3 times of the original level while maintaining the excellent strength of the Ti2AlNb material.

[0021] The technical solutions of the application will be further described in detail below with the help of the drawings and examples. DETAILED DESCRIPTION

[0022] Figure 1 The optical microstructure diagram of the Ti2AlNb alloy prepared in Example 1 of the application.

[0023] Figure 2 The optical microstructure diagram of the Ti2AlNb alloy prepared in Comparative Example 1 of the application.

[0024] Figure 3 The optical microstructure diagram of the Ti2AlNb alloy prepared in Comparative Example 2 of the application. DETAILED DESCRIPTION

[0025] Example 1 This example includes the following steps: Step one, set the scanning parameters: A three-dimensional CAD model of the target product is established, and the three-dimensional CAD model is divided into preset slice layers with equal thickness along the height direction of the three-dimensional CAD model to obtain preset slice layer data, and the preset slice layer data is subjected to layering processing to obtain layered scanning data, and then the layered scanning data is imported into an additive manufacturing device and additive manufacturing parameters and in-situ heat treatment parameters are set to obtain an additive manufacturing device with parameters; the layering processing is that, from bottom to top along the height direction of the three-dimensional CAD model, the odd-numbered layer preset slice layers are listed as a single stage, the even-numbered layer preset slice layers are listed as a double stage, and the single stage and the double stage are arranged longitudinally alternately; the Ti2AlNb powder is composed of the following components by mass percentage: Al 9.9%, Nb 43.6%, and the balance of Ti elements and other unavoidable impurities; the Ti2AlNb alloy powder has a particle size of 35 μm to 120 μm, a powder particle size D 50 =70 μm, and a powder bulk density of 3.5 g / cm 3 ; the preset slice layer has a layer thickness of 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 double-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; and 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.

[0026] Step two, pre-prepared entity slice layer: The Ti2AlNb powder is loaded into the powder bin of the additive manufacturing device with parameters obtained in step one, vacuum is drawn, and then inert gas is filled, and then the Ti2AlNb powder is uniformly spread on the upper surface of the stainless steel substrate, and then the electron beam emitter is started, and the spread Ti2AlNb powder is heated to complete melting according to the additive manufacturing parameters set in step one, and the pre-prepared entity slice layer is obtained after natural cooling; the layer thickness of the spread Ti2AlNb powder is the same as that of the preset slice layer in step one; the vacuum degree is 1.2×10 -3 Pa after vacuum drawing; the inert gas is commercial high-purity helium gas; Step three, in-situ heat treatment: The electron beam emitter is started, and the pre-prepared entity slice layer obtained in step two is subjected to in-situ heat treatment according to the in-situ heat treatment parameters set in step one, and the in-situ heat treated entity slice layer is obtained after natural cooling; the in-situ heat treatment is repeated scanning of the same pre-prepared entity slice layer by using an electron beam, and the scanning path is a snake shape or parallel lines; the in-situ heat treatment is annealing treatment: the temperature is 700 ℃, the time is 1 min, and the heat treatment slice layer depth is 50 μm; Step four, preparation of a component: The steps two to three of spreading Ti2AlNb powder, melting, cooling, in-situ heat treatment and natural cooling are repeated in sequence until the solid sheets after in-situ heat treatment are deposited layer by layer to obtain a preform, and then the preform is separated from the stainless steel substrate after furnace cooling to room temperature, thereby obtaining the Ti2AlNb alloy.

[0027] Figure 1 is an optical microstructure diagram of the Ti2AlNb alloy prepared in the embodiment, as shown in Figure 1 The Ti2AlNb alloy prepared in the embodiment has no unmelted powder and no hole in the interior, excellent metallurgical bonding, dense and uniform structure, and is beneficial to improve the alloy structure stability and mechanical properties.

[0028] The Ti2AlNb alloy prepared in the embodiment has a room temperature tensile strength of 1130 MPa, a yield strength of 991%, and a plasticity of 6%.

[0029] Comparative Example 1 The difference between the comparative example and the embodiment 1 is that the step one does not perform the layering treatment, and the additive manufacturing parameters include: an 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.

[0030] Figure 2 is an optical microstructure diagram of the Ti2AlNb alloy prepared in the comparative example, as shown in Figure 2 The Ti2AlNb alloy prepared in the comparative example has obvious holes in the interior, low structure uniformity, poor metallurgical bonding, and is not conducive to improving the alloy structure stability and mechanical properties.

[0031] The Ti2AlNb alloy prepared in the comparative example has a room temperature tensile strength of 862 MPa, a yield strength of 709 MPa, and a plasticity of 2.5%.

[0032] In combination of the comparative example and the embodiment 1, it is illustrated that if the sheet layer is not divided into levels and the sheet layer is not alternately combined and melted by scanning, the adjacent single-layer solid sheet layer will be overheated and remelted, the metallurgical bonding strength of the adjacent layer will be reduced, the structure stability and high-temperature mechanical properties will be greatly reduced, and the temperature resistance of the Ti2AlNb alloy will be not improved, and the material failure risk will be increased.

[0033] Comparative Example 2 The difference between the comparative example and the embodiment 1 is that the step three does not perform the in-situ heat treatment.

[0034] Figure 3 is an optical microstructure diagram of the Ti2AlNb alloy prepared in the comparative example, as shown in Figure 3As shown, the Ti2AlNb alloy prepared in the present comparative example has obvious holes inside, low uniformity of structure, poor metallurgical bonding, and low high-temperature structural stability. The tensile strength of the Ti2AlNb alloy prepared in the present comparative example is 620 MPa, the yield strength is 350 MPa, and the plasticity is 3.5%.

[0035] In combination with the present comparative example and Example 1, it is illustrated that without in-situ heat treatment, the metallurgical bonding strength of adjacent layers is reduced, the strength and plasticity of the alloy are reduced, and the risk of material failure is increased.

[0036] Example 2 The present example includes the following steps: Step one, set the scanning parameters: A three-dimensional CAD model of the target product is established, and the three-dimensional CAD model is divided into equal-thickness preset slices along the height direction of the three-dimensional CAD model to obtain preset slice data. The preset slice data is then subjected to layering processing to obtain layering scanning data. The layering scanning data is then imported into an additive manufacturing device and additive manufacturing parameters and in-situ heat treatment parameters are set to obtain an additive manufacturing device with parameters. The layering processing is as follows: along the height direction of the three-dimensional CAD model, from bottom to top, the odd-numbered layers of the preset slices are arranged as a single stage, the even-numbered layers of the preset slices are arranged as a double stage, and the single stage and the double stage are arranged longitudinally in an alternating manner. The Ti2AlNb powder is composed of the following components by mass percentage: Al 10.5%, Nb 42.5%, and the balance being Ti elements and other unavoidable impurities. The Ti2AlNb alloy powder has a particle size of 35 μm to 120 μm, a powder particle size D 50 = 75 μm, and a powder bulk density of 3.5 g / cm 3 . The preset slice has a layer thickness of 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 double-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. Step two, preform the slice layer: Ti2AlNb powder is loaded into the powder bin of the additive manufacturing device with the parameters obtained in step one, and after vacuumizing, inert gas is filled, then Ti2AlNb powder is uniformly spread on the upper surface of the stainless steel substrate, then the electron beam emitter is started, and the spread Ti2AlNb powder is heated to complete melting according to the additive manufacturing parameters set in step one, and after natural cooling, a pre-prepared entity sheet layer is obtained; the thickness of the spread Ti2AlNb powder layer is the same as the layer thickness of the pre-prepared sheet layer in step one; the vacuum degree is 1.2x10 -3 Pa after vacuumizing; the inert gas is commercial high-purity helium gas; Step three, in-situ heat treatment: The electron beam emitter is started, and the pre-prepared entity sheet layer obtained in step two is subjected to in-situ heat treatment according to the in-situ heat treatment parameters set in step one, and after natural cooling, an in-situ heat treated entity sheet layer is obtained; the in-situ heat treatment is repeated scanning of the same pre-prepared entity sheet layer by electron beam, and the scanning path is serpentine or parallel line; the in-situ heat treatment is annealing treatment: the temperature is 750℃, the time is 2min, and the heat treatment depth is 60μm; Step four, preparation of a component: The steps of spreading Ti2AlNb powder, melting, cooling, in-situ heat treatment and natural cooling in steps two to three are repeated in sequence until the in-situ heat treated entity sheet layers are stacked and deposited layer by layer to obtain a pre-prepared component, then the pre-prepared component is furnace cooled to room temperature, and then the pre-prepared component is separated from the stainless steel substrate to obtain a Ti2AlNb alloy.

[0037] It is detected that the Ti2AlNb alloy prepared in this embodiment is dense and defect-free inside, has high metallurgical bonding, dense and uniform structure, excellent high-temperature structure stability, room temperature tensile strength of 1100MPa, yield strength of 992MPa, and plasticity of 10%.

[0038] Example 3 This embodiment includes the following steps: Step one, setting scanning parameters: 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.

[0039] 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 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; 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: 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. Step 4: Preparing the components: The steps of spreading Ti2AlNb powder, melting, cooling, in-situ heat treatment and natural cooling in steps two to three are repeated in sequence until the solid pieces after each in-situ heat treatment are deposited layer by layer to obtain a preform, then the preform is separated from the stainless steel substrate after furnace cooling to room temperature, and a Ti2AlNb alloy is obtained.

[0040] It is detected that the Ti2AlNb alloy prepared in the embodiment is dense and defect-free inside, has excellent metallurgical bonding, compact structure and high uniformity, is beneficial to improve strength and plasticity, has a room temperature tensile strength of 1230 MPa, a yield strength of 1100 MPa and a plasticity of 10%.

[0041] The above is only a preferred embodiment of the present application, and does not limit the present application. Any simple modification, change and equivalent change of the above embodiment according to the technical essence of the present application still belongs to the protection scope of the technical solution of the present application.

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. 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. 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: Preparing the components: 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 additive manufacturing parameters mentioned in step one include: for single-stage electron beam scanning, the 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 dual-stage electron beam scanning, the 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.

5. 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.

6. 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.

7. 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.

8. 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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