Electron beam selective melting printing TiAl alloy and Al element loss inhibition method

Abstract

This invention provides an electron beam selective melting printing method for TiAl alloys and a method for suppressing Al element loss, relating to the technical field of engine material design and preparation. The Al element loss suppression method optimizes the phase transformation path and single-phase temperature range of the alloy through reasonable composition adjustment. By controlling factors such as preheating of the substrate, current and speed, and scan line settings during the preheating stage, and return time, current and speed, and scan line settings during the melting stage, the loss of Al element during printing is effectively controlled. This invention reduces the temperature difference between the powder and the molten pool, resulting in a fine, fully lamellar microstructure with uniform elements and grains. This microstructure exhibits good high-temperature performance, offering a novel concept for blade materials and processing; it also synergistically improves room-temperature and high-temperature mechanical properties, suppresses Al element loss, has high resource utilization, a short process, and high efficiency, facilitating large-scale industrial production and promotion.

Description

Technical Field

[0001] This invention relates to the technical field of engine material design and preparation, and in particular to an electron beam selective melting printing method for TiAl alloy and a method for suppressing Al element loss. Background Technology

[0002] TiAl-based intermetallic alloys possess excellent performance in high-temperature structural applications, exhibiting low density, superior oxidation resistance above 800°C, high strength, and outstanding high-temperature creep resistance, making them highly promising for the aerospace industry. Currently, most TiAl alloys are manufactured through conventional casting or powder metallurgy, resulting in long production cycles, complex shapes, and limited design freedom, often requiring additional post-processing to achieve customized shapes. Therefore, additive manufacturing offers an alternative method for rapidly manufacturing TiAl alloy parts with high design freedom.

[0003] Electron beam selective melting (EBM) operating under vacuum and preheated powder has proven to be a suitable method for producing TiAl components. However, the high temperatures during printing cause significant Al loss and heterogeneous distribution, which adversely affect mechanical properties. TiAl alloys typically exhibit four microstructures: near-gamma (NG), duplex, near-lamellar (NL), and fully lamellar (FL). Among these, the heterogeneous distribution caused by Al loss results in a "banded structure" with alternating layers of lamellar and equiaxed gamma grains. This heterogeneous structure significantly reduces the strength and ductility of TiAl alloys.

[0004] Studies have shown that Al loss during selective electron beam melting is approximately 0.5-2 at.%, and this loss is unavoidable. Therefore, most existing research focuses on maintaining a consistent Al loss ratio. The reasons for Al loss are twofold: firstly, Al volatilization occurs on the powder surface during the preheating stage when the beam scans the powder; secondly, the high surface temperature of the molten pool during melting makes Al more prone to volatilization, as indicated by saturated vapor pressure. Overcoming these two technical shortcomings is a pressing technical challenge that needs to be addressed.

[0005] Chinese patent CN116809965A discloses a method for eliminating layered microstructure in electron beam 3D printing of TiAl alloys. This method obtains TiAl alloy ingots with uniform bimodal or near-lamellar microstructures through heat treatment and unidirectional forging, thereby eliminating the layered heterogeneous inhomogeneous microstructure in the original ingot. Obviously, this method can only produce TiAl alloys with simple shapes. The products obtained by electron beam 3D printing do not have the shape and properties of the final product, and cannot fully utilize the direct forming technology advantages of electron beam 3D printing. Moreover, the total deformation of the low-carbon steel gasket is 40-45%, which is a large amount and increases the production cost.

[0006] Chinese patent CN117753990A discloses a method for eliminating the uneven microstructure of electron beam selective melting formed TiAl alloys. This method involves sequentially homogenizing and high-temperature heat treatment of the additively manufactured TiAl alloy. By performing segmented heat treatment on the TiAl alloy, the uneven grain bands in the direction of the forming powder, which are common in electron beam selective melting formed TiAl alloys, can be effectively eliminated, and the structure can be controlled to near-γ and dual-state structures, resulting in additively manufactured TiAl alloys with fine grains and uniform microstructure. While heat treatment can improve the uneven microstructure of the alloy, homogenization treatment is applied to the product itself, has a long processing time, and consumes a lot of heat energy, which can lead to grain growth and a decrease in overall mechanical properties.

[0007] Chinese patent CN116117164A discloses a method for controlling the microstructure during selective electron beam melting of TiAl alloy. By adding a heating process at the end of each layer preparation process, the brittle phase in the alloy is reduced, resulting in TiAl products with fewer forming defects, lower brittle phase content, and smaller and more uniform phase size and distribution. Although the heating process uses an electron beam, it involves many steps and is short in time. Some microstructures do not have enough time to change during the heating process, which is not conducive to product printing. In addition, the scanning speed and current of the electron beam are very high, resulting in high costs.

[0008] Chinese patent CN111485115A discloses a method for controlling Al volatilization by adjusting the vacuum level of an electron beam cold hearth furnace. This method involves adding a servo motor, frequency converter, controller, and vacuum level detection device to an existing conventional electron beam cold hearth furnace. The controller sets the allowable vacuum level range, coarse adjustment step value V, fine adjustment step value v, and time t. Real-time control of the vacuum pump drive motor speed is achieved using a power frequency converter and real-time vacuum level feedback. This method reduces and controls volatilization by selecting appropriate device structure and process parameters, primarily to control fluctuations in volatilization rate and mechanical properties, rather than to synergistically improve the room temperature and high temperature properties of the alloy product. Summary of the Invention

[0009] To address the technical problems of existing electron beam melting printing of TiAl alloys, such as the "banded structure" layering phenomenon, difficulty in effectively controlling aluminum volatilization loss, the fact that heat treatment and machining are applied only to the printed product, and the complexity, multiple processes, high energy consumption, high cost, and low efficiency in controlling the microstructure of the product, this invention provides an electron beam selective melting printing method for TiAl alloys that can synergistically improve room temperature and high temperature mechanical properties (especially) while suppressing Al loss. The technical solution is as follows:

[0010] An electron beam selective melting (EBM) printing method for TiAl alloy, wherein the height of the EBM-printed TiAl alloy for suppressing Al element loss is 15-300 mm, the thickness is 15-50 mm, and the chemical composition by atomic percentage is: Al 40-50 at%, Nb 2-10 at%, Mo 0-0.9 at%, Cr 0-2.5 at%, Si 0-2 at%, C 0-0.5 at%, with the balance being Ti and unavoidable inclusions; wherein the Al element loss is 0.2-0.35 at%.

[0011] Optionally, the electron beam selective melting printing of TiAl alloy is measured on a scale of one melt pool depth, and the difference in Al content should not exceed 0.5 at.%.

[0012] Optionally, the electron beam selective melting printing of the TiAl alloy has a multiphase structure, does not have the "banded structure" caused by Al removal, and contains 20-30% ordered D0 at room temperature. 19 The structure includes a Ti3Al phase, a β phase with an ordered B2 structure (volume fraction ≤10%), and a γ phase with an L10 structure (60-70%). In the microstructure, the region with 5-10% equiaxed γ grains has a γ grain content of no more than 30% compared to the region with 90-95% lamellar content.

[0013] Optionally, the electron beam selective melting printing of TiAl alloy that suppresses Al element loss has a strength and plasticity difference of no more than 10% in the forming direction and horizontal direction, and the strength and plasticity are improved by 20-50% respectively compared with the heterogeneous distribution caused by Al loss of 1-3 at%.

[0014] A method for suppressing Al element loss in electron beam selective melting printing of TiAl alloy according to claim 1, comprising the following steps:

[0015] S1. Melting: Weigh and batch the TiAl alloy according to the atomic percentage of the electron beam selective melting and printing, heat and melt it, refine it, and cast it to obtain an ingot;

[0016] S2. Alloy powder preparation: The S1 ingot is powdered by rotating electrode method or gas atomization, and then sieved to obtain the alloy powder required for electron beam selective melting printing of TiAl alloy.

[0017] S3, Powder Spreading: The alloy powder required for S2 is spread in an electron beam selective melting device, and the powder spread thickness is uniform.

[0018] S4. Preheating of the base plate: The base plate in the electron beam selective melting equipment is preheated. The preheating current adopts a two-stage method. The bottom of the sample is supported by a grid to reduce the temperature gradient and reduce the tendency of Al loss.

[0019] S5, printing of TiAl alloy: After preheating the S4 base plate, the alloy powder is melted and printed to obtain the TiAl alloy with the required shape, size and precision.

[0020] Optionally, the optimal powder thickness in S3 is close to half of the median powder particle size. At this point, the influence of the melt pool depth and the remelting heating effect is balanced, which is most beneficial for suppressing Al element loss. In production, a large layer thickness is often preferred for printing. In this case, more precise control of the melt depth and defocus value is required.

[0021] Optionally, the sieve size in S2 is 350 mesh, and the powder thickness in S3 is 40-120 μm.

[0022] Optionally, the preheating temperature of the base plate in S4 is 900-950℃, and the powder sintering temperature below the base plate is 850-900℃; in the two-stage method, the first stage method uses a smaller current, gradually increasing from 10mA to 40mA in 5-10 passes using an automatic interpolation method; the second stage method uses a larger current, gradually increasing from 40mA to 60mA in 5-10 passes using an automatic interpolation method.

[0023] Optionally, the electron beam scanning line in S4 is a vertical line that runs through the entire preheating area. After each scan, it is rotated 90°. The number of sub-lines in the preheating scanning line is 10-16, and the scanning line spacing is 0.2-1mm.

[0024] Optionally, the vacuum level in the printing chamber of the S4 is maintained at at least 10. -2 mbar, after evacuation, a small amount of high-purity argon gas is introduced and circulated two to three times.

[0025] Optionally, within 10ms after the base plate preheating is completed in S4, a molten beam should be output to melt and print the alloy powder; the melting and printing process in S5 includes the following steps:

[0026] S51, Return Time Setting: When dividing and slicing the model, the return time of the scan line is set to a fixed value. If a single line is too long, it will be re-divided into a combination of several short lines.

[0027] S52. Current-Speed ​​Selection: Set the return time in S51 and proceed with powder melting. The melting parameters for different types of powder can be determined using orthogonal experiments. For TiAl alloy powder, the following parameters are applicable: When the powder layer thickness is 40-70μm, the scanning speed is 1.8-2.8m / s, the scanning current is 3-6mA, the line spacing is 0.05-0.2mm, and the defocusing value is 20-30mA; When the powder layer thickness is 70-120μm, the scanning speed is 2.0-4.8m / s, the scanning current is 4-9mA, the line spacing is 0.05-0.2mm, and the defocusing value is 30-60mA.

[0028] S53, Scan line settings: In S52, the melting scan line adopts short line splicing, and rotates 90° after each layer. In the case of severe powder blowing tendency, the dehoff strategy or random strategy can be used instead.

[0029] Optionally, the microstructure of the TiAl alloy with the required shape, size, and precision in S5 was analyzed using energy dispersive spectroscopy (EDS) with scanning electron microscopy. The EDS images showed a uniform distribution of Al elements in each layer, with no significant contrast differences in the forming direction and horizontal direction. X-ray diffraction analysis was also used to determine D0 under different parameters. 19 The differences in the contents of the Ti3Al phase, the β phase of the B2 structure, and the γ phase of the L10 structure measured using the full width at half maximum (FWHM) method should not exceed 5%.

[0030] Optionally, in S5, the temperature difference between the top and bottom of the molten pool for any combination of printing parameters for the TiAl alloy of the desired shape, size, and precision shall not exceed 1500°C, and the temperature at the top of the molten pool shall not exceed 2500°C.

[0031] Optionally, after S5, in the powder recycling stage, powders that have turned grayish-black or bright white should be removed. These powders are generally caused by Al removal or Al plating.

[0032] Technical principle of the invention:

[0033] This method prints TiAl alloys without delamination, with an Al element distribution difference of no more than 0.5 at.% between the upper and lower parts of the molten pool, and a strength and plasticity difference of no more than 10% between the forming direction and the horizontal direction. This reduces the temperature difference between the powder and the molten pool, resulting in a fine, fully lamellar microstructure with uniform elements and grains. This microstructure exhibits good high-temperature performance, offering a novel approach to blade materials and processing.

[0034] The above technical solution has at least the following advantages compared with the existing technology:

[0035] The present invention proposes an electron beam selective melting printing method for TiAl alloy and a method for suppressing Al element loss, which can solve many technical problems existing in the current electron beam printing process of TiAl alloy, thereby reducing production costs and improving economic benefits.

[0036] This invention optimizes the phase transformation path and single-phase temperature range of the alloy through reasonable composition adjustment. By controlling factors such as base plate preheating, current and speed, and scan line settings in the preheating stage, and return time, current and speed, and scan line settings in the melting stage, the loss of Al elements during the printing process is effectively controlled.

[0037] This invention achieves a higher printing process window through optimized printing parameter design, which is beneficial for controlling the loss of Al elements during printing; it prints TiAl alloys without delamination, with the difference in Al element distribution between the upper and lower parts of the molten pool not exceeding 0.5 at.%, and the difference in strength and plasticity between the forming direction and the horizontal direction not exceeding 10%.

[0038] The preparation method of this invention completely eliminates the "banded structure" delamination phenomenon in TiAl alloys through parameter optimization design, reduces the temperature difference between the powder and the molten pool, and obtains a fine, fully lamellar structure with uniform elements and grains. This structure exhibits good high-temperature performance, offering a completely new concept for blade materials and processing.

[0039] The preparation method of this invention can be widely used to print TiAl alloys such as TNM, 4822, high Nb-TiAl, and 45XD, and can suppress aluminum loss. The alloy process is highly adaptable. In particular, the design parameters in the preparation method are controllable, requiring no additional equipment or steps. The process is simple, has a short cycle, low cost, and high efficiency.

[0040] In summary, compared with other traditional methods, the method of this invention, through component selection and control of the preheating and melting stages, prints TiAl alloy products with high freedom of shape design and high dimensional accuracy; it can synergistically improve room temperature and high temperature mechanical properties, suppress Al element loss, has high resource utilization, short process, high efficiency, and is conducive to large-scale industrial production and promotion. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a SEM-BSE image of TiAl alloy printed by electron beam selective melting in Comparative Example 1 of this invention;

[0043] Figure 2 This is a SEM-BSE image of TiAl alloy printed by electron beam selective melting using the Al element loss suppression method in Embodiment 1 of the present invention;

[0044] Figure 3 This is the SEM-BSE image of TiAl alloy printed by electron beam selective melting in Comparative Example 2 of this invention;

[0045] Figure 4 This is a SEM-BSE image of TiAl alloy printed by electron beam selective melting using the Al element loss suppression method in Embodiment 2 of the present invention;

[0046] Figure 5 This is the SEM-BSE image of TiAl alloy printed by electron beam selective melting in Comparative Example 3 of this invention;

[0047] Figure 6 This is a SEM-BSE image of TiAl alloy printed by electron beam selective melting using the Al element loss suppression method in Embodiment 3 of the present invention;

[0048] Figure 7 This is the SEM-BSE image of TiAl alloy printed by electron beam selective melting in Comparative Example 4 of this invention;

[0049] Figure 8 This is the SEM-BSE image of TiAl alloy printed by electron beam selective melting using the Al element loss suppression method in Embodiment 4 of the present invention;

[0050] Figure 9 This is a SEM-EDX image of TiAl alloy printed by electron beam selective melting using the Al element loss suppression method in Embodiment 5 of the present invention;

[0051] Figure 10 This is a SEM-EDX image of TiAl alloy printed by electron beam selective melting using the Al element loss suppression method in Embodiment 6 of the present invention;

[0052] Figure 11 In Embodiment 5 of this invention, the detection area of ​​TiAl alloy obtained by electron beam selective melting printing using an Al element loss suppression method is approximately 25 mm². 2 Ingredient content chart;

[0053] Figure 12 In Embodiment 6 of this invention, the detection area of ​​TiAl alloy obtained by electron beam selective melting printing using an Al element loss suppression method is approximately 25 mm². 2 Ingredient content chart;

[0054] Figure 13In Embodiment 7 of this invention, the detection area of ​​TiAl alloy obtained by electron beam selective melting printing using an Al element loss suppression method is approximately 25 mm². 2 Ingredient content chart;

[0055] Figure 14 This is a table showing the composition of 12 points of TiAl alloy obtained by electron beam selective melting printing using the Al element loss suppression method in Embodiment 7 of the present invention. Detailed Implementation

[0056] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0057] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.

[0058] In this embodiment of the invention, the terms "image" and "picture" may sometimes be used interchangeably. It should be noted that, without emphasizing the difference, their intended meanings are consistent. Similarly, the terms "of," "corresponding," and "corresponding" may sometimes be used interchangeably. It should be noted that, without emphasizing the difference, their intended meanings are consistent.

[0059] In this embodiment of the invention, sometimes a subscript such as W1 may be written in a non-subscript form such as W1. When the difference is not emphasized, the meaning they express is the same.

[0060] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0061] An electron beam selective melting (EBM) printing method for TiAl alloy, wherein the height of the EBM-printed TiAl alloy for suppressing Al element loss is 15-300 mm, the thickness is 15-50 mm, and the chemical composition by atomic percentage is: Al 40-50 at%, Nb 2-10 at%, Mo 0-0.9 at%, Cr 0-2.5 at%, Si 0-2 at%, C 0-0.5 at%, with the balance being Ti and unavoidable inclusions; wherein the Al element loss is 0.2-0.35 at%.

[0062] Specifically, the electron beam selective melting printing of TiAl alloy is measured at a scale of one molten pool depth, and the difference in Al content should not exceed 0.5 at.%.

[0063] Specifically, the electron beam selective melting printed TiAl alloy has a multiphase structure, does not have the "banded structure" caused by Al removal, and contains 20-30% ordered D0 at room temperature. 19 The structure includes a Ti3Al phase, a β phase with an ordered B2 structure (volume fraction ≤10%), and a γ phase with an L10 structure (60-70%). In the microstructure, the region with 5-10% equiaxed γ grains has a γ grain content of no more than 30% compared to the region with 90-95% lamellar content.

[0064] In particular, the electron beam selective melting printing of TiAl alloy that suppresses Al element loss has a strength and plasticity difference of no more than 10% in the forming direction and horizontal direction, and the strength and plasticity are improved by 20-50% respectively compared with the heterogeneous distribution caused by Al loss of 1-3 at%.

[0065] A method for suppressing Al element loss in electron beam selective melting printing of TiAl alloy according to claim 1, comprising the following steps:

[0066] S1. Melting: Weigh and batch the TiAl alloy according to the atomic percentage of the electron beam selective melting and printing, heat and melt it, refine it, and cast it to obtain an ingot;

[0067] S2. Alloy powder preparation: The S1 ingot is powdered by rotating electrode method or gas atomization, and then sieved to obtain the alloy powder required for electron beam selective melting printing of TiAl alloy.

[0068] S3, Powder Spreading: The alloy powder required for S2 is spread in an electron beam selective melting device, and the powder spread thickness is uniform.

[0069] S4. Preheating of the base plate: The base plate in the electron beam selective melting equipment is preheated. The preheating current adopts a two-stage method. The bottom of the sample is supported by a grid to reduce the temperature gradient and reduce the tendency of Al loss.

[0070] S5, printing of TiAl alloy: After preheating the S4 base plate, the alloy powder is melted and printed to obtain the TiAl alloy with the required shape, size and precision.

[0071] In particular, the optimal powder thickness in S3 is close to half of the median powder particle size. At this point, the influence of the melt pool depth and the remelting heating effect are balanced, which is most beneficial for suppressing Al element loss. In production, a large layer thickness is often used for printing, which requires more precise control of the melt depth and defocusing value.

[0072] Specifically, the sieve size in S2 is 350 mesh, and the powder thickness in S3 is 40-120 μm.

[0073] Specifically, the preheating temperature of the base plate in S4 is 900-950℃, and the powder sintering temperature below the base plate is 850-900℃. In the two-stage method, the first stage method uses a smaller current, gradually increasing from 10mA to 40mA in 5-10 passes using automatic interpolation. The second stage method uses a larger current, gradually increasing from 40mA to 60mA in 5-10 passes using automatic interpolation.

[0074] Specifically, the electron beam scanning line in S4 is a vertical line that runs through the entire preheating area. After each scan, it rotates 90°. The number of sub-lines in the preheating scanning line is 10-16, and the spacing between the scanning lines is 0.2-1mm.

[0075] Specifically, the vacuum level of the printing chamber in the S4 is maintained at at least 10. -2 mbar, after evacuation, a small amount of high-purity argon gas is introduced and circulated two to three times.

[0076] Specifically, within 10ms after the base plate preheating in S4, the molten beam should begin to be output for melting and printing the alloy powder; the melting and printing process in S5 includes the following steps:

[0077] S51, Return Time Setting: When dividing and slicing the model, the return time of the scan line is set to a fixed value. If a single line is too long, it will be re-divided into a combination of several short lines.

[0078] S52. Current-Speed ​​Selection: Set the return time in S51 and proceed with powder melting. The melting parameters for different types of powder can be determined using orthogonal experiments. For TiAl alloy powder, the following parameters are applicable: When the powder layer thickness is 40-70μm, the scanning speed is 1.8-2.8m / s, the scanning current is 3-6mA, the line spacing is 0.05-0.2mm, and the defocusing value is 20-30mA; When the powder layer thickness is 70-120μm, the scanning speed is 2.0-4.8m / s, the scanning current is 4-9mA, the line spacing is 0.05-0.2mm, and the defocusing value is 30-60mA.

[0079] S53, Scan line settings: In S52, the melting scan line adopts short line splicing, and rotates 90° after each layer. In the case of severe powder blowing tendency, the dehoff strategy or random strategy can be used instead.

[0080] Specifically, the microstructure of the TiAl alloy with the required shape, size, and precision in S5 was analyzed using energy dispersive spectroscopy (EDS) with scanning electron microscopy. The EDS images showed a uniform distribution of Al elements in each layer, with no significant contrast differences in the forming direction or the horizontal direction. X-ray diffraction analysis was used to determine the D0 value under different parameters. 19The differences in the contents of the Ti3Al phase, the β phase of the B2 structure, and the γ phase of the L10 structure measured using the full width at half maximum (FWHM) method should not exceed 5%.

[0081] Specifically, in S5, the temperature difference between the top and bottom of the molten pool for any combination of printing parameters for the TiAl alloy of the required shape, size, and precision shall not exceed 1500°C, and the temperature at the top of the molten pool shall not exceed 2500°C.

[0082] In particular, after S5, during the powder recycling stage, powders that have turned grayish-black or bright white should be removed. These powders are generally caused by Al removal or Al plating.

[0083] Example 1

[0084] In this embodiment, the TiAl alloy was printed by electron beam selective melting with a height of 15mm and a thickness of 15mm using an Al element loss suppression method. The chemical composition, by atomic percentage, is: Al 45at%, Nb 8at%, with the balance being Ti and unavoidable inclusions; wherein, the Al element loss is 0.2at.

[0085] A method for suppressing Al element loss in the electron beam selective melting printing of TiAl alloy based on this embodiment is as follows:

[0086] S1. Melting: Weigh and batch the TiAl alloy according to the atomic percentage of the electron beam selective melting and printing, heat and melt it, refine it, and cast it to obtain an ingot;

[0087] S2. Alloy powder preparation: The S1 ingot is powdered by rotating electrode method (PREP), and sieved with a mesh size of 350 to obtain the alloy powder required for electron beam selective melting printing of TiAl alloy.

[0088] S3, Powder Spreading: The alloy powder required for S2 is spread in an electron beam selective melting device with a powder spreading thickness of 50μm and uniform powder spreading thickness.

[0089] S4. Base Plate Preheating: Preheat the base plate in the electron beam selective melting equipment, maintaining the vacuum level of the printing chamber at at least 10. -2 The sample was evacuated to mbar and then filled with a small amount of high-purity argon gas, and the process was repeated two to three times. The preheating temperature of the base plate was 920℃, and the sintering temperature of the powder below the base plate was 850℃. A two-stage method was used for the preheating current. In the first stage, a smaller current was used, gradually increasing from 18mA to 38mA in 10 passes using automatic interpolation. In the second stage, a larger current was used, gradually increasing from 40mA to 58mA in 10 passes using automatic interpolation. A grid support was added to the bottom of the sample to reduce the temperature gradient and mitigate the tendency for Al loss.

[0090] Among them, the preheating electron beam scanning line adopts a vertical line that runs through the entire preheating area. After each scan, it rotates 90°. The number of preheating scanning lines is 10, and the scanning line spacing is 1mm.

[0091] Printing of S5 TiAl alloy: Within 10ms after the base plate of S5 is preheated, a molten beam should be output to melt and print the alloy powder, obtaining the required shape, size, and precision of the TiAl alloy; the melting and printing process includes the following steps:

[0092] S51, Return Time Setting: When dividing and slicing the model, the return time of the scan line is set to a fixed value. If a single line is too long, it will be re-divided into a combination of several short lines.

[0093] S52. Current-speed selection: Set the return time in S51 to melt the powder. The melting parameters for different types of powder can be determined by orthogonal experiment. The following parameters are applicable to TiAl alloy powder: scanning speed of 2.6m / s, scanning current of 5mA, line spacing of 0.08mm, and defocusing value of 30mA.

[0094] S53, Scan line settings: In S52, the melting scan line adopts short line splicing, and rotates 90° after each layer. In the case of severe powder blowing tendency, the dehoff strategy or random strategy can be used instead.

[0095] The microstructure of the TiAl alloy with the required shape, size, and precision in Example S5 was analyzed using energy dispersive spectroscopy (EDS) scanning electron microscopy. The microstructure was obtained using SEM-BSE. Figure 2 As shown, the molten pool has the same compositional contrast as the surrounding area, and the "layering" characteristic has been completely eliminated; moreover, the Al element is uniformly distributed in each layer, with no obvious contrast difference in the forming direction and the horizontal direction; using X-ray diffraction analysis, D0 under different parameters 19 The differences in the contents of the Ti3Al phase, the β phase of the B2 structure, and the γ phase of the L10 structure measured using the full width at half maximum (FWHM) method were as large as 3%.

[0096] In this embodiment S5, the temperature difference between the top and bottom of the molten pool for any combination of printing parameters for the TiAl alloy with the required shape, size, and precision is 1000°C, and the temperature at the top of the molten pool is 2200°C.

[0097] In this embodiment, after S5, the powder that turns grayish-black or bright white should be removed during the powder recycling stage. These powders are generally caused by Al removal or Al plating.

[0098] In this embodiment, the electron beam selective melting printing of TiAl alloy was measured at a depth of one molten pool, and the maximum difference in Al content was 1 at.%.

[0099] The TiAl alloy prepared by electron beam selective melting for printing in this embodiment has a multiphase structure and does not exhibit "banded structure" due to Al removal. It contains 20% ordered D0 at room temperature. 19 The structure contains a Ti3Al phase, a β phase with an ordered B2 structure (10% by volume), and a γ phase with an L10 structure (70%). In the microstructure, the region with 5% equiaxed γ grains has a γ grain content of no more than 30% compared to the region with 95% lamellar content.

[0100] The TiAl alloy to be prepared by electron beam selective melting printing in this embodiment has a maximum difference of 5% in strength and plasticity between the forming direction and the horizontal direction. Compared with the heterogeneous distribution caused by the loss of 1.5 at% of Al, the strength and plasticity are improved by 20% and 50%, respectively.

[0101] The room temperature properties of the electron beam selective melting printed TiAl alloy to be prepared in this embodiment are as follows in the forming direction: tensile strength of 950 MPa, yield strength of 800 MPa, and elongation of 1.5%.

[0102] Comparative Example 1

[0103] The thickness and composition of the electron beam selective melting printed TiAl alloy to be prepared in this comparative example are the same as those in Example 1. The preparation method is as follows:

[0104] The steps S1-S3 are the same as in Example 1;

[0105] S4. Preheating of the base plate: The base plate in the electron beam selective melting equipment is preheated to 1000℃, and the powder sintering temperature below the base plate is 980℃; the preheating current is 26-44mA scanned 30 times; no grid support is added to the bottom of the sample.

[0106] Among them, the electron beam scanning line for preheating is a vertical line that runs through the entire preheating area, and rotates 90° after each scan.

[0107] S5 and TiAl alloy printing: After the base plate of S5 is preheated, a melting beam is output to melt and print the alloy powder to obtain the required shape, size and precision of TiAl alloy; during the melting and printing process, the melting scanning speed is 2.0m / s, the scanning current is 8mA and the line spacing is 0.1mm.

[0108] The microstructure of the TiAl alloy with the required shape, size, and precision in Comparative Example S5 was analyzed using energy dispersive spectroscopy (EDS) scanning electron microscopy. The microstructure was obtained via SEM-BSE as follows: Figure 1 As shown, the molten pool exhibits a significant difference in compositional contrast with its surroundings, demonstrating a marked "layering" characteristic.

[0109] In this comparative example S5, the temperature difference between the top and bottom of the molten pool for any combination of printing parameters for the TiAl alloy with the required shape, size, and precision is 1900°C, and the temperature at the top of the molten pool is 3100°C.

[0110] In this comparative example, the electron beam selective melting printing of TiAl alloy was measured at a depth of one molten pool, and the difference in Al content was as small as 2.6 at.%.

[0111] The electron beam selective melting printing TiAl alloy to be prepared in this comparative example has the smallest difference in strength and plasticity between the forming direction and the horizontal direction, which is 20%.

[0112] The room-temperature properties of the electron beam selective melting printed TiAl alloy to be prepared in this comparative example to suppress Al element loss are as follows: tensile strength of 550 MPa, yield strength of 500 MPa, and elongation of 0.5%.

[0113] Example 2

[0114] In this embodiment, the TiAl alloy was printed by electron beam selective melting with a height of 35mm and a thickness of 15mm using an Al element loss suppression method. The chemical composition, by atomic percentage, is: Al 48at%, Cr 2at%, Nb 2at%, with the balance being Ti and unavoidable inclusions; wherein, the Al element loss is 0.22at.

[0115] A method for suppressing Al element loss in the electron beam selective melting printing of TiAl alloy based on this embodiment is as follows:

[0116] S1. Melting: Weigh and batch the TiAl alloy according to the atomic percentage of the electron beam selective melting and printing, heat and melt it, refine it, and cast it to obtain an ingot;

[0117] S2. Alloy powder preparation: The S1 ingot is powdered by rotating electrode method (PREP), and sieved with a mesh size of 350 to obtain the alloy powder required for electron beam selective melting printing of TiAl alloy.

[0118] S3, Powder Spreading: The alloy powder required for S2 is spread in an electron beam selective melting device with a powder spreading thickness of 50μm and uniform powder spreading thickness.

[0119] S4. Base Plate Preheating: Preheat the base plate in the electron beam selective melting equipment, maintaining the vacuum level of the printing chamber at at least 10. -2The sample was evacuated to mbar and then filled with a small amount of high-purity argon gas, and the process was repeated two to three times. The preheating temperature of the base plate was 920℃, and the sintering temperature of the powder below the base plate was 880℃. A two-stage method was used for the preheating current. In the first stage, a smaller current was used, gradually increasing from 16mA to 40mA in 10 passes using automatic interpolation. In the second stage, a larger current was used, gradually increasing from 40mA to 60mA in 8 passes using automatic interpolation. A grid support was added to the bottom of the sample to reduce the temperature gradient and mitigate the tendency for Al loss.

[0120] The preheating electron beam scanning line is a vertical line that runs through the entire preheating area. After each scan, it rotates 90°. There are 12 sub-lines in the preheating scanning line and the scanning line spacing is 1mm.

[0121] Printing of S5 TiAl alloy: Within 10ms after the base plate of S5 is preheated, a molten beam should be output to melt and print the alloy powder, obtaining the required shape, size, and precision of the TiAl alloy; the melting and printing process includes the following steps:

[0122] S51, Return Time Setting: When dividing and slicing the model, the return time of the scan line is set to a fixed value. If a single line is too long, it will be re-divided into a combination of several short lines.

[0123] S52, Current-Speed ​​Selection: Set the return time in S51 to melt the powder. The melting parameters for different types of powder can be determined by orthogonal experiment. The following parameters are applicable to TiAl alloy powder: scanning speed of 2.6m / s, scanning current of 5mA, line spacing of 0.08mm, and defocusing value of 35mA.

[0124] S53, Scan line settings: In S52, the melting scan line adopts short line splicing, and rotates 90° after each layer. In the case of severe powder blowing tendency, the dehoff strategy or random strategy can be used instead.

[0125] The microstructure of the TiAl alloy with the required shape, size, and precision in Example S5 was analyzed using energy dispersive spectroscopy (EDS) scanning electron microscopy. The microstructure was obtained using SEM-BSE. Figure 4 As shown, the molten pool has the same compositional contrast as the surrounding area, and the "layering" characteristic has been completely eliminated; moreover, the Al element is uniformly distributed in each layer, with no obvious contrast difference in the forming direction and the horizontal direction; using X-ray diffraction analysis, D0 under different parameters 19 The differences in the contents of the Ti3Al phase, the β phase of the B2 structure, and the γ phase of the L10 structure measured using the full width at half maximum (FWHM) method were as large as 3%.

[0126] In this embodiment S5, the temperature difference between the top and bottom of the molten pool for any combination of printing parameters for the TiAl alloy with the required shape, size, and precision is 800°C, and the temperature at the top of the molten pool is 2000°C.

[0127] In this embodiment, after S5, the powder that turns grayish-black or bright white should be removed during the powder recycling stage. These powders are generally caused by Al removal or Al plating.

[0128] In this embodiment, the electron beam selective melting printing of TiAl alloy was measured at a depth of one molten pool, and the maximum difference in Al content was 0.4 at.%.

[0129] The TiAl alloy prepared by electron beam selective melting for printing in this embodiment has a multiphase structure and does not exhibit "banded structure" due to Al removal. It contains 25% ordered D0 at room temperature. 19 The microstructure contains Ti3Al phase, 6% β phase with ordered B2 structure and 69% γ phase with L10 structure; the region with equiaxed γ grains is 6% larger than the region with 94% lamellar content, and the number of equiaxed γ grains is 20%.

[0130] The TiAl alloy to be prepared by electron beam selective melting printing in this embodiment has a maximum difference of 7% in strength and plasticity between the forming direction and the horizontal direction. Compared with the heterogeneous distribution caused by the loss of 2.8 at% of Al, the strength and plasticity are improved by 40% and 50%, respectively.

[0131] The room temperature properties of the electron beam selective melting printed TiAl alloy to be prepared in this embodiment are as follows in the forming direction: tensile strength of 800 MPa, yield strength of 700 MPa, and elongation of 1.2%.

[0132] Comparative Example 2

[0133] The thickness and composition of the electron beam selective melting printed TiAl alloy to be prepared in this comparative example are the same as those in Example 2. The preparation method is as follows:

[0134] The steps S1-S3 are the same as in Example 1;

[0135] S4. Preheating of the base plate: The base plate in the electron beam selective melting equipment is preheated to a temperature of 980℃, and the powder sintering temperature below the base plate is 900℃. The preheating current is 28-45mA scanned 26 times. No mesh support is added to the bottom of the sample.

[0136] Among them, the electron beam scanning line for preheating is a vertical line that runs through the entire preheating area, and rotates 90° after each scan.

[0137] S5 and TiAl alloy printing: After the base plate of S5 is preheated, a molten beam is output to melt and print the alloy powder to obtain the required shape, size and precision of TiAl alloy; during the melting and printing process, the melting scanning speed is 1.6m / s, the scanning current is 8.2mA and the line spacing is 0.12mm.

[0138] The microstructure of the TiAl alloy with the required shape, size, and precision in Comparative Example S5 was analyzed using energy dispersive spectroscopy (EDS) scanning electron microscopy. The microstructure was obtained via SEM-BSE as follows: Figure 3 As shown, the molten pool exhibits a significant difference in compositional contrast with its surroundings, demonstrating a marked "layering" characteristic.

[0139] In this comparative example S5, the temperature difference between the top and bottom of the molten pool for any combination of printing parameters for the TiAl alloy with the required shape, size, and precision is 1800°C, and the temperature at the top of the molten pool is 2700°C.

[0140] In this comparative example, the electron beam selective melting printing of TiAl alloy was measured at a depth of one molten pool, and the difference in Al content was as small as 2.5 at.%.

[0141] The electron beam selective melting printing TiAl alloy to be prepared in this comparative example has the smallest difference in strength and plasticity between the forming direction and the horizontal direction, which is 46%.

[0142] The room-temperature properties of the electron beam selective melting printed TiAl alloy to be prepared in this comparative example to suppress Al element loss are as follows: tensile strength of 630 MPa, yield strength of 570 MPa, and elongation of 0.3%.

[0143] Example 3

[0144] In this embodiment, the TiAl alloy was printed by electron beam selective melting with a height of 75mm and a thickness of 15mm using an Al element loss suppression method. The chemical composition, by atomic percentage, is: Al 44.5at%, Nb 4at%, Mo 0.5at%, with the balance being Ti and unavoidable inclusions; wherein, the Al element loss is 0.32at.

[0145] A method for suppressing Al element loss in the electron beam selective melting printing of TiAl alloy based on this embodiment is as follows:

[0146] S1. Melting: Weigh and batch the TiAl alloy according to the atomic percentage of the electron beam selective melting and printing, heat and melt it, refine it, and cast it to obtain an ingot;

[0147] S2. Alloy powder preparation: The S1 ingot is powdered by rotating electrode method (PREP), and sieved with a mesh size of 350 to obtain the alloy powder required for electron beam selective melting printing of TiAl alloy.

[0148] S3, Powder Spreading: The alloy powder required for S2 is spread in an electron beam selective melting device with a powder spreading thickness of 70μm and uniform powder spreading thickness.

[0149] S4. Base Plate Preheating: Preheat the base plate in the electron beam selective melting equipment, maintaining the vacuum level of the printing chamber at at least 10. -2 The sample was evacuated to mbar and then filled with a small amount of high-purity argon gas, and the process was repeated two to three times. The preheating temperature of the base plate was 920℃, and the sintering temperature of the powder below the base plate was 870℃. A two-stage method was used for the preheating current. In the first stage, a smaller current was used, gradually increasing from 16mA to 36mA in 10 passes using automatic interpolation. In the second stage, a larger current was used, gradually increasing from 38mA to 48mA in 10 passes using automatic interpolation. A grid support was added to the bottom of the sample to reduce the temperature gradient and mitigate the tendency for Al loss.

[0150] The preheating electron beam scanning line is a vertical line that runs through the entire preheating area. After each scan, it rotates 90°. There are 12 sub-lines in the preheating scanning line and the scanning line spacing is 1mm.

[0151] Printing of S5 TiAl alloy: Within 10ms after the base plate of S5 is preheated, a molten beam should be output to melt and print the alloy powder, obtaining the required shape, size, and precision of the TiAl alloy; the melting and printing process includes the following steps:

[0152] S51, Return Time Setting: When dividing and slicing the model, the return time of the scan line is set to a fixed value. If a single line is too long, it will be re-divided into a combination of several short lines.

[0153] S52, Current-Speed ​​Selection: Set the return time in S51 to melt the powder. The melting parameters for different types of powder can be determined by orthogonal experiments. The following parameters are applicable to TiAl alloy powder: scanning speed of 2.8m / s, scanning current of 5.5mA, line spacing of 0.1mm, and defocusing value of 40mA.

[0154] S53, Scan line settings: In S52, the melting scan line adopts short line splicing, and rotates 90° after each layer. In the case of severe powder blowing tendency, the dehoff strategy or random strategy can be used instead.

[0155] The microstructure of the TiAl alloy with the required shape, size, and precision in Example S5 was analyzed using energy dispersive spectroscopy (EDS) scanning electron microscopy. The microstructure was obtained using SEM-BSE. Figure 6 As shown, the molten pool has the same compositional contrast as the surrounding area, and the "layering" characteristic has been completely eliminated; moreover, the Al element is uniformly distributed in each layer, with no obvious contrast difference in the forming direction and the horizontal direction; using X-ray diffraction analysis, D0 under different parameters 19 The content of the Ti3Al phase, the β phase of the B2 structure, and the γ phase of the L10 structure differed by a maximum of 2% when measured using the full width at half maximum (FWHM) method.

[0156] In this embodiment S5, the temperature difference between the top and bottom of the molten pool for any combination of printing parameters for the TiAl alloy with the required shape, size, and precision is 1200°C, and the temperature at the top of the molten pool is 2200°C.

[0157] In this embodiment, after S5, the powder that turns grayish-black or bright white should be removed during the powder recycling stage. These powders are generally caused by Al removal or Al plating.

[0158] In this embodiment, the electron beam selective melting printing of TiAl alloy was measured at a depth of one molten pool, and the maximum difference in Al content was 0.8 at.%.

[0159] The TiAl alloy to be prepared by electron beam selective melting printing in this embodiment has a multiphase structure and does not have a "banded structure" caused by Al removal.

[0160] The TiAl alloy to be prepared by electron beam selective melting printing in this embodiment has a maximum difference of 4% in strength and plasticity between the forming direction and the horizontal direction. Compared with the heterogeneous distribution caused by the loss of 1.8 at% of Al, the strength and plasticity are improved by 30% and 60%, respectively.

[0161] The room temperature properties of the electron beam selective melting printed TiAl alloy to be prepared in this embodiment are as follows in the forming direction: tensile strength of 920 MPa, yield strength of 860 MPa, and elongation of 1.5%.

[0162] Comparative Example 3

[0163] The thickness and composition of the electron beam selective melting printed TiAl alloy to be prepared in this comparative example are the same as those in Example 3. The preparation method is as follows:

[0164] The steps S1-S3 are the same as in Example 1;

[0165] S4. Preheating of the base plate: The base plate in the electron beam selective melting equipment is preheated to a temperature of 950°C, and the powder sintering temperature below the base plate is 800°C. The preheating current is 20-48mA scanned 32 times. No mesh support is added to the bottom of the sample.

[0166] Among them, the electron beam scanning line for preheating is a vertical line that runs through the entire preheating area, and rotates 90° after each scan.

[0167] Printing of S5 and TiAl alloy: After the base plate of S5 is preheated, a melting beam is output to melt and print the alloy powder to obtain the required shape, size and precision of TiAl alloy; during the melting and printing process, the melting scanning speed is 3.2m / s, the scanning current is 12mA and the line spacing is 0.15mm.

[0168] The microstructure of the TiAl alloy with the required shape, size, and precision in Comparative Example S5 was analyzed using energy dispersive spectroscopy (EDS) scanning electron microscopy. The microstructure was obtained via SEM-BSE as follows: Figure 5 As shown, the molten pool exhibits a significant difference in compositional contrast with its surroundings, demonstrating a marked "layering" characteristic.

[0169] In this comparative example S5, the temperature difference between the top and bottom of the molten pool for any combination of printing parameters for the TiAl alloy with the required shape, size, and precision is 1600°C, and the temperature at the top of the molten pool is 2900°C.

[0170] The electron beam selective melting printing of TiAl alloys prepared in this comparative example was measured at a scale of one melt pool depth, and the difference in Al content was as small as 1.4 at.%.

[0171] The electron beam selective melting printing TiAl alloy to be prepared in this comparative example has the smallest difference in strength and plasticity between the forming direction and the horizontal direction, which is 23%.

[0172] The room-temperature properties of the electron beam selective melting printed TiAl alloy to be prepared in this comparative example to suppress Al element loss are as follows: tensile strength of 560 MPa, yield strength of 490 MPa, and elongation of 0.5%.

[0173] Example 4

[0174] In this embodiment, the TiAl alloy was printed by electron beam selective melting with a height of 150 mm and a thickness of 15 mm using an Al element loss suppression method. The chemical composition is: Ti45Al2Nb2Mn0.8 vol.%TiB2 (45XD-TiAl); wherein, the Al element loss is 0.26 at.

[0175] A method for suppressing Al element loss in the electron beam selective melting printing of TiAl alloy based on this embodiment is as follows:

[0176] S1. Melting: Weigh and batch the TiAl alloy according to the atomic percentage of the electron beam selective melting and printing, heat and melt it, refine it, and cast it to obtain an ingot;

[0177] S2. Alloy powder preparation: The S1 ingot is powdered by rotating electrode method (PREP), and sieved through a 350-mesh sieve to obtain the alloy powder required for electron beam selective melting printing of TiAl alloy.

[0178] S3, Powder Spreading: The alloy powder required for S2 is spread in an electron beam selective melting device with a powder spreading thickness of 70μm and uniform powder spreading thickness.

[0179] S4. Base Plate Preheating: Preheat the base plate in the electron beam selective melting equipment, maintaining the vacuum level of the printing chamber at at least 10. -2 The sample was evacuated to mbar and then filled with a small amount of high-purity argon gas, and the process was repeated two to three times. The preheating temperature of the base plate was 920℃, and the sintering temperature of the powder below the base plate was 900℃. A two-stage method was used for the preheating current. In the first stage, a smaller current was used, gradually increasing from 14mA to 36mA in 11 passes using automatic interpolation. In the second stage, a larger current was used, gradually increasing from 38mA to 52mA in 12 passes using automatic interpolation. A grid support was added to the bottom of the sample to reduce the temperature gradient and mitigate the tendency for Al loss.

[0180] Among them, the preheating electron beam scanning line adopts a vertical line that runs through the entire preheating area. After each scan, it rotates 90°. The number of preheating scanning lines is 14, and the scanning line spacing is 1mm.

[0181] Printing of S5 TiAl alloy: Within 10ms after the base plate of S5 is preheated, a molten beam should be output to melt and print the alloy powder, obtaining the required shape, size, and precision of the TiAl alloy; the melting and printing process includes the following steps:

[0182] S51, Return Time Setting: When dividing and slicing the model, the return time of the scan line is set to a fixed value. If a single line is too long, it will be re-divided into a combination of several short lines.

[0183] S52, Current-Speed ​​Selection: Set the return time in S51 to melt the powder. The melting parameters for different types of powder can be determined by orthogonal experiments. The following parameters are applicable to TiAl alloy powder: scanning speed of 2.2m / s, scanning current of 6.5mA, line spacing of 0.1mm, and defocusing value of 35mA.

[0184] S53, Scan line settings: In S52, the melting scan line adopts short line splicing, and rotates 90° after each layer. In the case of severe powder blowing tendency, the dehoff strategy or random strategy can be used instead.

[0185] The microstructure of the TiAl alloy with the required shape, size, and precision in Example S5 was analyzed using energy dispersive spectroscopy (EDS) scanning electron microscopy. The microstructure was obtained using SEM-BSE. Figure 8 As shown, the molten pool has the same compositional contrast as the surrounding area, and the "layering" characteristic has been completely eliminated; moreover, the Al element is uniformly distributed in each layer, with no obvious contrast difference in the forming direction and the horizontal direction; using X-ray diffraction analysis, D0 under different parameters 19 The differences in the contents of the Ti3Al phase, the β phase of the B2 structure, and the γ phase of the L10 structure measured using the full width at half maximum (FWHM) method were as large as 3%.

[0186] In this embodiment S5, the temperature difference between the top and bottom of the molten pool for any combination of printing parameters for the TiAl alloy with the required shape, size, and precision is 1700°C, and the temperature at the top of the molten pool is 2900°C.

[0187] In this embodiment, after S5, the powder that turns grayish-black or bright white should be removed during the powder recycling stage. These powders are generally caused by Al removal or Al plating.

[0188] In this embodiment, the electron beam selective melting printing of TiAl alloy was measured at a depth of one molten pool, and the maximum difference in Al content was 1.3 at.%.

[0189] The TiAl alloy prepared by electron beam selective melting for printing in this embodiment has a multiphase structure and does not exhibit "banded structure" due to Al removal. It contains 25% ordered D0 at room temperature. 19 The microstructure contains Ti3Al phase, 7% β phase with ordered B2 structure and 68% γ phase with L10 structure; the region with equiaxed γ grains is 5% larger than the region with 95% lamellar content, and the number of equiaxed γ grains is 25%.

[0190] The TiAl alloy to be prepared by electron beam selective melting printing in this embodiment has the largest difference in strength and plasticity between the forming direction and the horizontal direction, which is 12%. Compared with the heterogeneous distribution caused by the loss of 2 at% Al, the strength and plasticity are improved by 35% and 56%, respectively.

[0191] The room temperature properties of the electron beam selective melting printed TiAl alloy to be prepared in this embodiment are as follows in the forming direction: tensile strength of 860 MPa, yield strength of 790 MPa, and elongation of 1.4%.

[0192] Comparative Example 4

[0193] The thickness and composition of the electron beam selective melting printed TiAl alloy to be prepared in this comparative example are the same as those in Example 4. The preparation method is as follows:

[0194] The steps S1-S3 are the same as in Example 1;

[0195] S4. Preheating of the base plate: The base plate in the electron beam selective melting equipment is preheated to a temperature of 970℃, and the powder sintering temperature below the base plate is 900℃. The preheating current is 28-48mA scanned 36 times. No mesh support is added to the bottom of the sample.

[0196] Among them, the electron beam scanning line for preheating is a vertical line that runs through the entire preheating area, and rotates 90° after each scan.

[0197] S5 and TiAl alloy printing: After the base plate of S5 is preheated, a melting beam is output to melt and print the alloy powder to obtain the TiAl alloy with the required shape, size and precision; during the melting and printing process, the melting scanning speed is 2.0m / s, the scanning current is 8.8mA and the line spacing is 0.12mm.

[0198] The microstructure of the TiAl alloy with the required shape, size, and precision in Comparative Example S5 was analyzed using energy dispersive spectroscopy (EDS) scanning electron microscopy. The microstructure was obtained via SEM-BSE as follows: Figure 7 As shown, the molten pool exhibits a significant difference in compositional contrast with its surroundings, demonstrating a marked "layering" characteristic.

[0199] In this comparative example S5, the temperature difference between the top and bottom of the molten pool for any combination of printing parameters for the TiAl alloy with the required shape, size, and precision is 1750°C, and the temperature at the top of the molten pool is 3200°C.

[0200] The electron beam selective melting printing of TiAl alloys prepared in this comparative example was measured at a scale of one melt pool depth, and the difference in Al content was as small as 1.2 at.%.

[0201] The electron beam selective melting printing TiAl alloy to be prepared in this comparative example has the smallest difference in strength and plasticity between the forming direction and the horizontal direction, which is 23%.

[0202] The room-temperature properties of the electron beam selective melting printed TiAl alloy to be prepared in this comparative example to suppress Al element loss are as follows: tensile strength of 640 MPa, yield strength of 520 MPa, and elongation of 0.6%.

[0203] Example 5

[0204] In this embodiment, the TiAl alloy was printed by electron beam selective melting with a height of 190mm and a thickness of 20mm using an Al element loss suppression method. The chemical composition, by atomic percentage, is: Al 44.5at%, Nb 4at%, Mo 0.5at%, with the balance being Ti and unavoidable inclusions; wherein, the Al element loss is 0.3at.

[0205] A method for suppressing Al element loss in the electron beam selective melting printing of TiAl alloy based on this embodiment is as follows:

[0206] S1. Melting: Weigh and batch the TiAl alloy according to the atomic percentage of the electron beam selective melting and printing, heat and melt it, refine it, and cast it to obtain an ingot;

[0207] S2. Alloy powder preparation: The S1 ingot is powdered by rotating electrode method (PREP), and sieved with a mesh size of 350 to obtain the alloy powder required for electron beam selective melting printing of TiAl alloy.

[0208] S3, Powder Spreading: The alloy powder required for S2 is spread in an electron beam selective melting device with a powder spreading thickness of 70μm and uniform powder spreading thickness.

[0209] S4. Base Plate Preheating: Preheat the base plate in the electron beam selective melting equipment, maintaining the vacuum level of the printing chamber at at least 10. -2 The sample was evacuated to mbar and then filled with a small amount of high-purity argon gas, and the process was repeated two to three times. The preheating temperature of the base plate was 920℃, and the sintering temperature of the powder below the base plate was 890℃. The preheating current was applied using a two-stage method. In the first stage, a smaller current was used, gradually increasing from 16mA to 38mA in eight passes using automatic interpolation. In the second stage, a larger current was used, gradually increasing from 40mA to 58mA in twelve passes using automatic interpolation. A grid support was added to the bottom of the sample to reduce the temperature gradient and mitigate the tendency for Al loss.

[0210] Among them, the preheating electron beam scanning line adopts a vertical line that runs through the entire preheating area. After each scan, it rotates 90°. The number of preheating scanning lines is 14, and the scanning line spacing is 1mm.

[0211] Printing of S5 TiAl alloy: Within 10ms after the base plate of S5 is preheated, a molten beam should be output to melt and print the alloy powder, obtaining the required shape, size, and precision of the TiAl alloy; the melting and printing process includes the following steps:

[0212] S51, Return Time Setting: When dividing and slicing the model, the return time of the scan line is set to a fixed value. If a single line is too long, it will be re-divided into a combination of several short lines.

[0213] S52, Current-Speed ​​Selection: Set the return time in S51 to melt the powder. The melting parameters for different types of powder can be determined by orthogonal experiments. The following parameters are applicable to TiAl alloy powder: scanning speed of 2.2m / s, scanning current of 5.5mA, line spacing of 0.1mm, and defocusing value of 35mA.

[0214] S53, Scan line settings: In S52, the melting scan line adopts short line splicing, and rotates 90° after each layer. In the case of severe powder blowing tendency, the dehoff strategy or random strategy can be used instead.

[0215] The microstructure of the TiAl alloy with the required shape, size, and precision in Example S5 was analyzed using energy dispersive spectroscopy (EDS) scanning electron microscopy. The microstructure was obtained using SEM-BSE. Figure 9 As shown, the molten pool has the same compositional contrast as the surrounding area, and the "layering" characteristic has been completely eliminated; moreover, the Al element is uniformly distributed in each layer, with no obvious contrast difference in the forming direction and the horizontal direction; using X-ray diffraction analysis, D0 under different parameters 19 The content of the Ti3Al phase, the β phase of the B2 structure, and the γ phase of the L10 structure differed by a maximum of 4% when measured using the full width at half maximum (FWHM) method.

[0216] The composition of the TiAl alloy prepared in this embodiment is as follows: Figure 11 As shown, the printed composition is close to the preset composition, and the loss of Al is controllable.

[0217] In this embodiment S5, the temperature difference between the top and bottom of the molten pool for any combination of printing parameters for the TiAl alloy with the required shape, size, and precision is 1100°C, and the temperature at the top of the molten pool is 2000°C.

[0218] In this embodiment, after S5, the powder that turns grayish-black or bright white should be removed during the powder recycling stage. These powders are generally caused by Al removal or Al plating.

[0219] In this embodiment, the electron beam selective melting printing of TiAl alloy was measured at a depth of one molten pool, and the maximum difference in Al content was 0.3 at.%.

[0220] The TiAl alloy prepared by electron beam selective melting for printing in this embodiment has a multiphase structure and does not exhibit "banded structure" due to Al removal. It contains 22% ordered D0 at room temperature. 19 The structure contains a Ti3Al phase, a β phase with an ordered B2 structure (5% by volume), and a γ phase with an L10 structure (63%). In the microstructure, the region with 8% equiaxed γ grains has a γ grain content of no more than 30% compared to the region with 92% lamellar content.

[0221] The TiAl alloy to be prepared by electron beam selective melting printing in this embodiment has the largest difference in strength and plasticity between the forming direction and the horizontal direction, which is 11%. The strength and plasticity are improved by 45% and 60% respectively compared with the heterogeneous distribution caused by the loss of 2 at% Al.

[0222] The room temperature properties of the electron beam selective melting printed TiAl alloy to be prepared in this embodiment are as follows in the forming direction: tensile strength of 940 MPa, yield strength of 900 MPa, and elongation of 1.6%.

[0223] Example 6

[0224] In this embodiment, the TiAl alloy was printed by electron beam selective melting with a height of 260 mm and a thickness of 30 mm using an Al element loss suppression method. The chemical composition, by atomic percentage, is: Al 44.5 at%, Nb 4 at%, Mo 0.5 at%, with the balance being Ti and unavoidable inclusions; wherein, the Al element loss is 0.28 at.

[0225] A method for suppressing Al element loss in the electron beam selective melting printing of TiAl alloy based on this embodiment is as follows:

[0226] S1. Melting: Weigh and batch the TiAl alloy according to the atomic percentage of the electron beam selective melting and printing, heat and melt it, refine it, and cast it to obtain an ingot;

[0227] S2. Alloy powder preparation: The S1 ingot is powdered by rotating electrode method (PREP), and sieved with a mesh size of 350 to obtain the alloy powder required for electron beam selective melting printing of TiAl alloy.

[0228] S3, Powder Spreading: The alloy powder required for S2 is spread in an electron beam selective melting device with a powder spreading thickness of 100μm and uniform powder spreading thickness.

[0229] S4. Base Plate Preheating: Preheat the base plate in the electron beam selective melting equipment, maintaining the vacuum level of the printing chamber at at least 10. -2 The sample was evacuated to mbar and then filled with a small amount of high-purity argon gas, and the process was repeated two to three times. The preheating temperature of the base plate was 900℃, and the sintering temperature of the powder below the base plate was also 900℃. A two-stage method was used for the preheating current. In the first stage, a smaller current was used, gradually increasing from 18mA to 40mA in 10 passes using automatic interpolation. In the second stage, a larger current was used, gradually increasing from 40mA to 58mA in 12 passes using automatic interpolation. A grid support was added to the bottom of the sample to reduce the temperature gradient and mitigate the tendency for Al loss.

[0230] Among them, the preheating electron beam scanning line adopts a vertical line that runs through the entire preheating area. After each scan, it rotates 90°. The number of preheating scanning lines is 14, and the scanning line spacing is 1mm.

[0231] Printing of S5 TiAl alloy: Within 10ms after the base plate of S5 is preheated, a molten beam should be output to melt and print the alloy powder, obtaining the required shape, size, and precision of the TiAl alloy; the melting and printing process includes the following steps:

[0232] S51, Return Time Setting: When dividing and slicing the model, the return time of the scan line is set to a fixed value. If a single line is too long, it will be re-divided into a combination of several short lines.

[0233] S52, Current-Speed ​​Selection: Set the return time in S51 to melt the powder. The melting parameters for different types of powder can be determined by orthogonal experiments. The following parameters are applicable to TiAl alloy powder: scanning speed of 2.8m / s, scanning current of 5.5mA, line spacing of 0.1mm, and defocusing value of 40mA.

[0234] S53, Scan line settings: In S52, the melting scan line adopts short line splicing, and rotates 90° after each layer. In the case of severe powder blowing tendency, the dehoff strategy or random strategy can be used instead.

[0235] The microstructure of the TiAl alloy with the required shape, size, and precision in Example S5 was analyzed using energy dispersive spectroscopy (EDS) scanning electron microscopy. The microstructure was obtained using SEM-BSE. Figure 10 As shown, the molten pool has the same compositional contrast as the surrounding area, and the "layering" characteristic has been completely eliminated; moreover, the Al element is uniformly distributed in each layer, with no obvious contrast difference in the forming direction and the horizontal direction; using X-ray diffraction analysis, D0 under different parameters 19 The differences in the contents of the Ti3Al phase, the β phase of the B2 structure, and the γ phase of the L10 structure measured using the full width at half maximum (FWHM) method were as large as 3%.

[0236] The composition of the TiAl alloy prepared in this embodiment is as follows: Figure 12 As shown, the printed composition is close to the preset composition, and the loss of Al is controllable.

[0237] In this embodiment S5, the temperature difference between the top and bottom of the molten pool for any combination of printing parameters for the TiAl alloy with the required shape, size, and precision is 1300°C, and the temperature at the top of the molten pool is 2100°C.

[0238] In this embodiment, after S5, the powder that turns grayish-black or bright white should be removed during the powder recycling stage. These powders are generally caused by Al removal or Al plating.

[0239] In this embodiment, the electron beam selective melting printing of TiAl alloy was measured at a depth of one molten pool, and the maximum difference in Al content was 0.7 at.%.

[0240] The TiAl alloy prepared by electron beam selective melting for printing in this embodiment has a multiphase structure and does not exhibit "banded structure" due to Al removal. It contains 26% ordered D0 at room temperature. 19 The structure contains a Ti3Al phase, a β phase with an ordered B2 structure (9% by volume), and a γ phase with an L10 structure (65% by volume). In the microstructure, the region with equiaxed γ grains (6%) has a fraction of less than 30% compared to the region with 94% lamellar content.

[0241] The TiAl alloy to be prepared by electron beam selective melting printing in this embodiment has the largest difference in strength and plasticity between the forming direction and the horizontal direction by 7%. The strength and plasticity are improved by 24% and 31% respectively compared with the heterogeneous distribution caused by the loss of 2 at% Al.

[0242] The room temperature properties of the electron beam selective melting printed TiAl alloy to be prepared in this embodiment are as follows in the forming direction: tensile strength of 870 MPa, yield strength of 800 MPa, and elongation of 1.6%.

[0243] Example 7

[0244] In this embodiment, TiAl alloy was printed by electron beam selective melting with a height of 300 mm and a thickness of 20 mm using an Al element loss suppression method. The chemical composition, by atomic percentage, is: Al 44.5 at%, Nb 4 at%, Mo 0.5 at%, with the balance being Ti and unavoidable inclusions; wherein, the Al element loss is 0.22 at.

[0245] A method for suppressing Al element loss in the electron beam selective melting printing of TiAl alloy based on this embodiment is as follows:

[0246] S1. Melting: Weigh and batch the TiAl alloy according to the atomic percentage of the electron beam selective melting and printing, heat and melt it, refine it, and cast it to obtain an ingot;

[0247] S2. Alloy powder preparation: The S1 ingot is powdered by rotating electrode method (PREP), and sieved through a 350-mesh sieve to obtain the alloy powder required for electron beam selective melting printing of TiAl alloy.

[0248] S3, Powder Spreading: The alloy powder required for S2 is spread in an electron beam selective melting device with a powder spreading thickness of 50μm and uniform powder spreading thickness.

[0249] S4. Base Plate Preheating: Preheat the base plate in the electron beam selective melting equipment, maintaining the vacuum level of the printing chamber at at least 10. -2 The sample was evacuated to mbar and then filled with a small amount of high-purity argon gas, and the process was repeated two to three times. The preheating temperature of the base plate was 910℃, and the sintering temperature of the powder below the base plate was 870℃. The preheating current was applied using a two-stage method. In the first stage, a smaller current was used, gradually increasing from 18mA to 38mA in eight passes using automatic interpolation. In the second stage, a larger current was used, gradually increasing from 40mA to 58mA in ten passes using automatic interpolation. A grid support was added to the bottom of the sample to reduce the temperature gradient and mitigate the tendency for Al loss.

[0250] Among them, the preheating electron beam scanning line adopts a vertical line that runs through the entire preheating area. After each scan, it rotates 90°. The number of preheating scanning lines is 10, and the scanning line spacing is 1mm.

[0251] Printing of S5 TiAl alloy: Within 10ms after the base plate of S5 is preheated, a molten beam should be output to melt and print the alloy powder, obtaining the required shape, size, and precision of the TiAl alloy; the melting and printing process includes the following steps:

[0252] S51, Return Time Setting: When dividing and slicing the model, the return time of the scan line is set to a fixed value. If a single line is too long, it will be re-divided into a combination of several short lines.

[0253] S52, Current-Speed ​​Selection: Set the return time in S51 to melt the powder. The melting parameters for different types of powder can be determined using orthogonal experiments. The following parameters are applicable to TiAl alloy powder: scanning speed of 2.4 m / s, scanning current of 4.5 mA, line spacing of 0.1 mm, and defocusing value of 35 mA.

[0254] S53, Scan line settings: In S52, the melting scan line adopts short line splicing, and rotates 90° after each layer. In the case of severe powder blowing tendency, the dehoff strategy or random strategy can be used instead.

[0255] The microstructure of the TiAl alloy with the required shape, size, and precision in Example S5 of this embodiment was analyzed using energy dispersive spectroscopy (EDS) with a scanning electron microscope. The printed microstructure composition curve is shown below. Figure 13 As shown, the printed composition is close to the preset composition, and the Al loss is controllable. Twelve points are evenly selected on the entire sample, and the composition is as follows. Figure 14As shown, the Al element is uniformly distributed across the entire forming surface. Specifically, the compositional contrast between the molten pool and its surroundings is the same, and the "layering" characteristic has been completely eliminated; moreover, the Al element is uniformly distributed in each layer, with no significant contrast difference in the forming direction or the horizontal direction; using X-ray diffraction analysis, D0 under different parameters... 19 The differences in the contents of the Ti3Al phase, the β phase of the B2 structure, and the γ phase of the L10 structure measured using the full width at half maximum (FWHM) method were as large as 3%.

[0256] In this embodiment S5, the temperature difference between the top and bottom of the molten pool for any combination of printing parameters for the TiAl alloy with the required shape, size, and precision is 1000°C, and the temperature at the top of the molten pool is 1900°C.

[0257] In this embodiment, after S5, the powder that turns grayish-black or bright white should be removed during the powder recycling stage. These powders are generally caused by Al removal or Al plating.

[0258] In this embodiment, the electron beam selective melting printing of TiAl alloy was measured at a depth of one molten pool, and the maximum difference in Al content was 0.4 at.%.

[0259] The TiAl alloy prepared by electron beam selective melting for printing in this embodiment has a multiphase structure and does not exhibit "banded structure" due to Al removal. It contains 29% ordered D0 at room temperature. 19 The structure contains a Ti3Al phase, a β phase with an ordered B2 structure (5% by volume), and a γ phase with an L10 structure (66%). In the microstructure, the region with 5% equiaxed γ grains has a γ grain content of no more than 30% compared to the region with 95% lamellar content.

[0260] The TiAl alloy to be prepared by electron beam selective melting printing in this embodiment has the largest difference in strength and plasticity between the forming direction and the horizontal direction, which is 12%. Compared with the heterogeneous distribution caused by the 2% loss of Al, the strength and plasticity are improved by 46% and 72%, respectively.

[0261] The room temperature properties of the electron beam selective melting printed TiAl alloy to be prepared in this embodiment are as follows in the forming direction: tensile strength of 980 MPa, yield strength of 900 MPa, and elongation of 1.3%.

[0262] The present invention proposes an electron beam selective melting printing method for TiAl alloys to suppress Al element loss and its preparation method. This method can solve many technical problems existing in the current electron beam printing process of TiAl alloys, thereby reducing production costs and improving economic benefits.

[0263] This invention optimizes the phase transformation path and single-phase temperature range of the alloy through reasonable composition adjustment. By controlling factors such as base plate preheating, current and speed, and scan line settings in the preheating stage, and return time, current and speed, and scan line settings in the melting stage, the loss of Al elements during the printing process is effectively controlled.

[0264] This invention achieves a higher printing process window through optimized printing parameter design, which is beneficial for controlling the loss of Al elements during printing; it prints TiAl alloys without delamination, with the difference in Al element distribution between the upper and lower parts of the molten pool not exceeding 0.5 at.%, and the difference in strength and plasticity between the forming direction and the horizontal direction not exceeding 10%.

[0265] The preparation method of this invention completely eliminates the "banded structure" delamination phenomenon in TiAl alloys through parameter optimization design, reduces the temperature difference between the powder and the molten pool, and obtains a fine, fully lamellar structure with uniform elements and grains. This structure exhibits good high-temperature performance, offering a completely new concept for blade materials and processing.

[0266] The preparation method of this invention can be widely used to print TiAl alloys such as TNM, 4822, high Nb-TiAl, and 45XD, and can suppress aluminum loss. The alloy process is highly adaptable. In particular, the design parameters in the preparation method are controllable, requiring no additional equipment or steps. The process is simple, has a short cycle, low cost, and high efficiency.

[0267] In summary, compared with other traditional methods, the method of this invention, through component selection and control of the preheating and melting stages, prints TiAl alloy products with high freedom of shape design and high dimensional accuracy; it can synergistically improve room temperature and high temperature mechanical properties, suppress Al element loss, has high resource utilization, short process, high efficiency, and is conducive to large-scale industrial production and promotion.

[0268] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. Additionally, the character " / " in this article generally indicates an "or" relationship between the preceding and following related objects, but it can also represent an "and / or" relationship. Please refer to the context for a more accurate understanding.

[0269] In this invention, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be a single item or multiple items.

[0270] It should be understood that, in various embodiments of the present invention, the order of the above-mentioned process numbers does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0271] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for selective electron beam melting printing of TiAl alloy, characterized in that, Electron beam selective melting (EBM) printing of TiAl alloys with suppressed Al element loss has a height of 15-300 mm and a thickness of 15-50 mm. The chemical composition, by atomic percentage, is: Al 40-50 at%, Nb 2-10 at%, Mo 0-0.9 at%, Cr 0-2.5 at%, Si 0-2 at%, C 0-0.5 at%, with the balance being Ti and unavoidable inclusions; the Al element loss is 0.2-0.35 at%. The electron beam selective melting printing of TiAl alloy was measured at a depth of one molten pool, and the difference in Al content was no greater than 0.5 at.%. The electron beam selective melting printing of TiAl alloy exhibits a multiphase structure, lacks the "banded structure" caused by Al removal, and contains 20-30% ordered D0 at room temperature. 19 The microstructure contains a Ti3Al phase, a β phase with an ordered B2 structure (volume fraction ≤10%), and a γ phase with an L10 structure (60-70%). In the microstructure, the region with 5-10% equiaxed γ grains has a γ grain content of no more than 30% compared to the region with 90-95% lamellar content. The electron beam selective melting printing of TiAl alloy, which suppresses Al element loss, has a strength and plasticity difference of no more than 10% in the forming direction and horizontal direction. Compared with the heterogeneous distribution caused by Al loss of 1-3 at%, the strength and plasticity are improved by 20-50%.

2. A method for suppressing Al element loss in TiAl alloy by electron beam selective melting printing according to claim 1, characterized in that, The method for suppressing Al element loss in TiAl alloy by selective electron beam melting printing is as follows: S1. Melting: Weigh and batch the TiAl alloy according to the atomic percentage of the electron beam selective melting and printing, heat and melt it, refine it, and cast it to obtain an ingot; S2. Alloy powder preparation: The S1 ingot is powdered by rotating electrode method or gas atomization, and then sieved to obtain the alloy powder required for electron beam selective melting printing of TiAl alloy. S3, Powder Spreading: The alloy powder required for S2 is spread in an electron beam selective melting device, and the powder spread thickness is uniform. S4. Preheating of the base plate: The base plate in the electron beam selective melting equipment is preheated. The preheating current adopts a two-stage method, and a grid support is added to the bottom of the sample. S5, printing of TiAl alloy: After preheating the S4 base plate, the alloy powder is melted and printed to obtain the required shape, size and precision of TiAl alloy.

3. The method for suppressing Al element loss in electron beam selective melting printing of TiAl alloy according to claim 2, characterized in that, The sieve size in S2 is 350 mesh, and the powder thickness in S3 is 40-120 μm.

4. The method for suppressing Al element loss in electron beam selective melting printing of TiAl alloy according to claim 3, characterized in that, The preheating temperature of the base plate in S4 is 900-950℃, and the sintering temperature of the powder below the base plate is 850-900℃. In the two-stage method, the first stage method uses a smaller current, gradually increasing from 10mA to 40mA in 5-10 passes using automatic interpolation. The second stage method uses a larger current, gradually increasing from 40mA to 60mA in 5-10 passes using automatic interpolation.

5. The method for suppressing Al element loss in electron beam selective melting printing of TiAl alloy according to claim 4, characterized in that, In S4, the preheating electron beam scanning line is a vertical line that runs through the entire preheating area. After each scan, it is rotated 90°. The number of preheating scanning lines is 10-16, and the scanning line spacing is 0.2-1mm.

6. The method for suppressing Al element loss in electron beam selective melting printing of TiAl alloy according to claim 4, characterized in that, Within 10ms after the base plate in S4 is preheated, a molten beam should be output to melt and print the alloy powder; the melting and printing process in S5 includes the following steps: S51, Return Time Setting: When dividing and slicing the model, the return time of the scan line is set to a fixed value. If a single line is too long, it will be re-divided into a combination of several short lines. S52. Current-Speed ​​Selection: Set the return time in S51 and proceed with powder melting. The melting parameters for different types of powder can be determined using orthogonal experiments. For TiAl alloy powder, the following parameters are applicable: When the powder layer thickness is 40-70μm, the scanning speed is 1.8-2.8m / s, the scanning current is 3-6mA, the line spacing is 0.05-0.2mm, and the defocusing value is 20-30mA; When the powder layer thickness is 70-120μm, the scanning speed is 2.0-4.8m / s, the scanning current is 4-9mA, the line spacing is 0.05-0.2mm, and the defocusing value is 30-60mA. S53, Scan line settings: In S52, the melting scan line adopts short line splicing, and rotates 90° after each layer. In the case of severe powder blowing tendency, the dehoff strategy or random strategy can be used instead.

7. The method for suppressing Al element loss in electron beam selective melting printing of TiAl alloy according to claim 2, characterized in that, The microstructure of the TiAl alloy with the required shape, size, and precision in S5 was analyzed using energy dispersive spectroscopy (EDS) with scanning electron microscopy. The EDS images showed a uniform distribution of Al elements in each layer, with no significant contrast difference in the forming direction or the horizontal direction. X-ray diffraction analysis was used to determine the D0 value under different parameters. 19 The differences in the contents of the Ti3Al phase, the β phase of the B2 structure, and the γ phase of the L10 structure measured using the full width at half maximum (FWHM) method should not exceed 5%.

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