A Ti / Al dissimilar metal integrated additive manufacturing method based on niobium-based intermediate layer interface structure replacement

Abstract

The present invention belongs to the technical field of metal additive manufacturing and metal material connection, and discloses a Ti / Al dissimilar metal integrated additive manufacturing method based on the replacement of niobium-based intermediate layer interface structure. The method is to add a niobium intermediate layer at the interface of titanium alloy and aluminum alloy to form a Ti-Nb-Al double interface transition to replace the Ti-Al single interface, blocking the interdiffusion of Ti and Al, and replacing the interfacial brittle intermetallic compounds TiAl3 and Ti3Al with Nb-Ti solid solution, Nb-Al compound and other Nb-containing compounds, thereby effectively solving the problem of interface cracking and preparing Ti / Al dissimilar metal with good interface bonding and stable overall performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal additive manufacturing and metal material connection, and in particular relates to a Ti / Al dissimilar metal integrated additive manufacturing method based on niobium-based intermediate layer interface structure replacement. Background Art

[0002] Titanium alloys have become key structural materials in the aerospace, automotive and consumer electronics sectors due to their excellent specific strength, corrosion resistance and fracture toughness. However, their high raw material costs and complex processing techniques have significantly restricted their large-scale application. In contrast, aluminum alloys occupy an important position in lightweight design due to their light weight, mature forming process and economic advantages. By combining Ti / Al dissimilar materials, the high-temperature performance of titanium alloys and the low-cost characteristics of aluminum alloys can be synergistically utilized to meet the urgent needs of lightweight and functional integration in scenarios such as aircraft engine hot end components and spacecraft fuel pipelines.

[0003] Despite the significant advantages of titanium / aluminum composite components, the significant differences in their physical and chemical properties make interfacial metallurgical bonding difficult: the melting points of titanium (1668°C) and aluminum (660°C) differ significantly, and their coefficients of thermal expansion differ by a factor of three. At high temperatures, brittle intermetallic compounds (IMCs) such as TiAl3 and Ti3Al are easily formed, severely weakening the mechanical properties of the interface. Traditional joining techniques, such as diffusion welding, require long, high-temperature treatments, which exacerbate the thickening of the IMC layer. While friction stir welding can suppress IMCs, it is limited by its adaptability to complex component processing. Riveting introduces additional weight and poses the risk of stress concentration, making it difficult to meet the high reliability requirements of aviation components.

[0004] Additive manufacturing technology provides a new paradigm for the integrated forming of titanium / aluminum heterostructures. Laser directed energy deposition (L-DED), with its high degree of design freedom and multi-material gradient control capabilities, can achieve topological optimization and composition-structure collaborative design of frame-beam components. However, the layer-by-layer melting characteristics of L-DED exacerbate the challenges of the Ti / Al interface: the rapid solidification of the molten pool leads to an imbalance in the interdiffusion kinetics of elements, and the segregation of IMCs forms a continuous brittle layer; the difference in thermal conductivity between titanium and aluminum causes non-uniform thermal stress accumulation, which promotes the initiation and propagation of cracks along the interface. Studies have shown that the shear strength of the Ti / Al interface formed by conventional L-DED is only 94.5-119.4 MPa, and the fracture mode is mainly brittle, which seriously restricts the service life of the component.

[0005] Current technical bottlenecks focus on controlling interfacial metallurgical reactions and regulating residual stresses. On the one hand, excessive interdiffusion of Ti and Al elements must be suppressed to limit the thickness of the IMC layer; on the other hand, thermal cycling must be optimized to mitigate interfacial stress concentration caused by thermal mismatch. While existing processes such as pre-installed transition layers and pulsed laser modulation can partially improve interfacial properties, they face challenges such as high process complexity and reduced forming efficiency. Therefore, developing an L-DED process that combines efficient forming with optimized interfacial properties is key to realizing the engineering application of aviation-grade Ti / Al heterogeneous components. Summary of the Invention

[0006] In order to overcome the shortcomings and deficiencies in the prior art, the purpose of the present invention is to provide a Ti / Al dissimilar metal integrated additive manufacturing method based on the replacement of the niobium-based intermediate layer interface structure; this method changes the Ti-Al dissimilar metal connection interface structure through a double-layer or multi-layer niobium intermediate layer, thereby realizing a laser additive manufacturing method for high-strength, toughness and stable connection of titanium (Ti) and aluminum (Al) dissimilar alloys, which is suitable for the integrated lightweight manufacturing of complex structural parts in the fields of aerospace, new energy vehicles, etc.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] A Ti / Al dissimilar metal integrated additive manufacturing method based on niobium-based interlayer interface structure replacement includes the following steps: printing multiple niobium deposits on the surface of a titanium alloy substrate using a laser directed energy deposition process, and then printing an aluminum alloy layer on the surface of the niobium deposits using a laser directed energy deposition process. This method adds a niobium interlayer at the interface between the titanium and aluminum alloys to form a Ti-Nb-Al double interface instead of a single Ti-Al interface, blocking the interdiffusion of Ti and Al. The brittle intermetallic compounds TiAl3 and Ti3Al at the Ti-Al interface are replaced with Nb-Ti solid solutions, Nb-Al compounds, and other Nb-containing compounds.

[0009] The above-mentioned Ti / Al dissimilar metal integrated additive manufacturing method based on niobium-based intermediate layer interface structure replacement specifically includes the following operating steps.

[0010] (1) Spherical pure niobium powder is prepared by plasma atomization, and spherical aluminum alloy powder is prepared by gas atomization or centrifugal atomization. The powder particle size distribution is 53~200μm. The powder is dried before printing;

[0011] (2) The titanium alloy substrate is ultrasonically cleaned and dried, and then transferred into an argon-protected laser cladding forming chamber through an intermediate chamber and placed above a forming base. The oxygen content in the forming chamber is ≤100 ppm;

[0012] (3) Using 3D solid modeling software, establish a 3D solid model of the niobium intermediate layer and a 3D solid model of the aluminum alloy component;

[0013] (4) Importing the 3D solid model into the path planning and process setting software of the laser directed energy deposition (L-DED) forming equipment, setting the printing process parameters of the niobium intermediate layer and the aluminum alloy component respectively, and generating the printing path;

[0014] (5) The first layer of niobium deposition with a thickness of 300~600µm is first deposited on the titanium alloy substrate using the laser directed energy deposition process. During the deposition of the first layer of niobium deposition, the laser forms a molten pool at the Ti-Nb interface. The titanium alloy at the bottom of the molten pool melts and stirs with the niobium melt to form a Ti-Nb solid solution. Part of the titanium element diffuses to the top of the molten pool, eventually forming a layer of Ti-Nb element gradient transition solid solution.

[0015] (6) Continuing to deposit a second niobium deposition layer on the basis of the first niobium deposition layer, the scanning direction of the cladding head is 30° to 90° with respect to the first niobium deposition layer, and finally further reducing the atomic percentage of Ti element in the upper part of the second niobium deposition layer to below 5%; continuing to deposit the third to fifth niobium deposition layers in sequence on the basis of the second niobium deposition layer, or directly proceeding to the subsequent step (7); the resulting multi-layer niobium deposition layer forms a niobium intermediate layer with a total thickness of 0.6-3.0 mm;

[0016] (7) Printing aluminum alloy on the basis of the niobium intermediate layer, the Nb element and the Al element in the aluminum alloy are fully fused below the aluminum alloy printing molten pool, and a multi-layered phase structure composed of Nb2Al, NbAl3 and other Nb-containing compounds is formed at the interface;

[0017] (8) Continue printing and forming according to the printing process parameters and printing path of the aluminum alloy component until the entire component is printed;

[0018] (9) The components formed by laser directed energy deposition are subjected to stress relief annealing to obtain Ti / Al dissimilar metal integrated additive materials based on the replacement of the niobium-based intermediate layer interface structure.

[0019] The titanium alloy substrate in step (2) is a titanium alloy with a grade of Ti-6Al-4V, TA15 or TC11.

[0020] In step (2), a 5-10 mm thick graphite felt is used between the titanium alloy substrate and the forming base for thermal insulation, thereby reducing the cooling rate of the laser directed energy deposition (L-DED) forming and reducing the concentration of thermal stress at the interface.

[0021] In step (5), a layer of titanium alloy solid is first deposited on the surface of the titanium alloy substrate, and then a first niobium deposition layer is deposited on the deposited titanium alloy solid.

[0022] After the three-dimensional solid model is imported into the path planning and process setting software of the laser directed energy deposition forming equipment in step (4), the thickness of each deposition layer is set to 0.3-0.6 mm, the lifting amount of each layer of the cladding head is consistent with the thickness of each deposition layer, and the powder feeding rate of niobium is set to 5-20 g / min and the powder feeding rate of aluminum alloy is set to 3-8 g / min.

[0023] The printing process parameters in step (4) are as follows:

[0024] The printing process parameters of the niobium intermediate layer are: laser power P 1200 W~1800 W, scanning rate v The scanning speed is 350mm / min~800mm / min, and the spacing between two adjacent scans is 0.6 mm~1.8 mm, interlayer cooling time t 0~50s;

[0025] The printing process parameters of the aluminum alloy component are: laser power P 800 W~1500 W, scanning rate v The scanning speed is 420mm / min~840mm / min, and the scanning distance between two adjacent passes is 0.6mm~1.8mm, interlayer cooling time t 0~60s.

[0026] The composition of the aluminum alloy in step (7) is AlSi 10 Mg or other aluminum-silicon alloys or high-strength aluminum alloys; the multi-layered phase structure includes a lower Nb-Al interface layer containing Nb2Al, NbAl3 and other Nb-containing compounds, and an upper Nb-Al element diffusion layer containing NbAl3.

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

[0028] The present invention can significantly improve the interfacial bonding strength of Ti / Al dissimilar alloy materials. By replacing the Ti-Al direct connection interface with Nb-Ti solid solution, Nb-Al compound and other Nb-containing compound interfaces, the formation of Ti-Al binary brittle IMCs is effectively avoided, the interface microstructure is significantly improved and thermal stress is reduced, macro- and micro-crack defects at the interface are directly avoided, and the comprehensive performance and service stability of the component are greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1This is a schematic diagram of the laser directed energy deposition (L-DED) forming process for the Ti / Al dissimilar alloy sample based on the replacement of the niobium-based intermediate layer interface structure, where (a) is the actual forming process, (b) is the principle diagram, 1 is the powder inlet, 2 is the laser cladding head, 3 is the powder, 4 is the laser spot, 5 is the aluminum alloy deposition layer, 6 is the niobium intermediate layer, 7 is the titanium alloy substrate, 8 is the working platform, 9 is the first layer, 10 is the second layer, 11 is the third layer, and 12 is the fourth layer.

[0030] Figure 2 These are photos of Ti / Al dissimilar alloys and Ti / Al dissimilar metal integrated additive samples prepared by L-DED forming of the present invention based on the replacement of the niobium-based intermediate layer interface structure, where (a) is a real photo, and (b) is a metallographic micrograph of the sample cross section with two niobium deposition layers deposited, where 13 represents interface cracking, 14 is the aluminum alloy deposition layer, 15 is the Nb-Al element diffusion layer, 16 is the Nb-Al interface, 17 is the second niobium deposition layer, 18 is the Nb-Ti solid solution zone, and 19 is the titanium alloy substrate.

[0031] Figure 3 This is the element distribution diagram of the interface layer in the Ti / Al dissimilar metal integrated additive material based on the replacement of the niobium-based intermediate layer interface structure prepared by L-DED forming of the present invention.

[0032] Figure 4 Figure 2 is the microstructure and local magnified image of the Nb-Al interface in the Ti / Al dissimilar metal integrated additive material based on the replacement of the niobium-based intermediate layer interface structure prepared by L-DED forming of the present invention, where (a) is the microstructure, and (b) and (c) are local magnified images.

[0033] Figure 5 This is a detection diagram of the Nb-Al interface phase composition in the Ti / Al dissimilar metal integrated additive material based on the niobium-based intermediate layer interface structure replacement prepared by L-DED forming of the present invention, where (a) is the XRD analysis diagram, and (b1, b2) are EBSD phase composition diagrams.

[0034] Figure 6 This is a microhardness curve of the Al-Nb-Ti double interface in the Ti / Al dissimilar metal integrated additive material prepared by L-DED forming based on the replacement of the niobium-based intermediate layer interface structure. DETAILED DESCRIPTION

[0035] The present invention will be described in further detail below with reference to the embodiments and drawings, but the embodiments of the present invention are not limited thereto.

[0036] The present invention is based on a Ti / Al dissimilar metal integrated additive manufacturing method using a niobium-based intermediate layer interface structure replacement, specifically following the steps below:

[0037] (1) Spherical pure niobium powder is prepared by plasma atomization, and spherical aluminum alloy powder is prepared by gas atomization or centrifugal atomization. The powder particle size distribution is 53~200μm. The powder is dried before printing;

[0038] (2) The titanium alloy substrate is ultrasonically cleaned and dried, and then transferred into an argon-protected laser cladding forming chamber through an intermediate chamber and placed above a forming base. The oxygen content of the forming chamber is ≤100ppm. A 5-10mm thick graphite felt is used between the titanium alloy substrate and the forming base for thermal insulation to reduce the cooling rate of laser directed energy deposition (L-DED) forming and reduce the concentration of thermal stress on the interface. The titanium alloy substrate is a titanium alloy with the grades of Ti-6Al-4V, TA15, and TC11.

[0039] (3) Using 3D solid modeling software on a computer, establish a 3D solid model of the niobium intermediate layer and a 3D solid model of the aluminum alloy component;

[0040] (4) Importing the 3D solid model into the path planning and process setting software of the laser directed energy deposition (L-DED) forming equipment, setting the printing process parameters of the niobium intermediate layer and the aluminum alloy component respectively, and generating the printing path;

[0041] After the three-dimensional solid model is imported into the path planning and process setting software of the laser directed energy deposition forming equipment, the thickness of each deposition layer is set to 0.3-0.6 mm, the lifting amount of each layer of the cladding head is consistent with the thickness of each deposition layer, the niobium powder feeding rate is set to 5-20 g / min, and the aluminum alloy powder feeding rate is set to 3-8 g / min.

[0042] The printing process parameters of the niobium intermediate layer are as follows: laser power P is 1200 W to 1800 W, scanning speed v is 350 mm / min to 800 mm / min, and the spacing between two adjacent scanning passes is 100 mm / min to 100 mm / min. The thickness is 0.6 mm to 1.8 mm, and the interlayer cooling time t is 0 to 50 s;

[0043] The printing process parameters of the aluminum alloy component are as follows: laser power P is 800 W~1500 W, scanning speed v is 420 mm / min~840 mm / min, and the spacing between two adjacent scanning passes is 100 mm / min. The thickness is 0.6mm~1.8mm, and the interlayer cooling time t is 0~60s.

[0044] (5) The first layer of niobium deposition with a thickness of 300-600 μm is first deposited on the titanium alloy substrate using the laser directed energy deposition process. During the deposition of the first layer of niobium deposition, the laser forms a molten pool at the Ti-Nb interface. The titanium alloy at the bottom of the molten pool melts and stirs with the niobium melt to form a Ti-Nb solid solution. Part of the titanium element diffuses to the top of the molten pool, eventually forming a layer of Ti-Nb element gradient transition solid solution.

[0045] (6) Continuing to deposit a second niobium deposit layer on the basis of the first niobium deposit layer, the scanning direction of the cladding head is 30°~90° with respect to the first niobium deposit layer, and finally further reducing the atomic percentage of Ti element in the upper part of the second niobium deposit layer to below 5%; continuing to deposit the third to fifth niobium deposit layers in sequence on the basis of the second niobium deposit layer, or directly proceeding to the subsequent step of depositing an aluminum alloy layer; the resulting multi-layer niobium deposit layer forms a niobium intermediate layer with a total thickness of 0.6-3.0 mm;

[0046] (7) Printing aluminum alloy on the basis of niobium intermediate layer, the composition of aluminum alloy is AlSi 10 Mg or other aluminum-silicon alloys or high-strength aluminum alloys, the Nb element and the Al element in the aluminum alloy are fully fused below the aluminum alloy printing molten pool, and a multi-component multi-layer phase structure composed of Nb2Al, NbAl3 and other Nb-containing compounds is formed at the interface; the multi-component multi-layer phase structure mainly includes a lower Nb-Al interface layer containing Nb2Al, NbAl3 and other Nb-containing compounds, and an upper Nb-Al element diffusion layer containing NbAl3;

[0047] (8) Continue printing and forming according to the printing process parameters of the aluminum alloy component and the printing path generated by the software until the entire component is printed;

[0048] (9) The components formed by laser directed energy deposition are subjected to stress relief annealing to obtain Ti / Al dissimilar metal integrated additive materials based on the replacement of the niobium-based intermediate layer interface structure.

[0049] According to the requirements of the target material, some need to first deposit a layer of titanium alloy entity on the surface of the titanium alloy substrate, and then deposit the first niobium deposition layer on the deposited titanium alloy entity.

[0050] Example 1

[0051] A Ti / Al dissimilar metal integrated additive manufacturing method based on niobium-based intermediate layer interface structure replacement, L-DED forming preparation of pure niobium intermediate layer transition Ti / Al dissimilar alloy sample process and printing strategy schematic diagram as shown in Figure 1 As shown, follow these steps:

[0052] (1) Spherical pure niobium powder was prepared by plasma atomization method, and spherical AlSi was prepared by centrifugal atomization method. 10 Mg powder, with a particle size distribution of 53-200µm, was dried before printing;

[0053] (2) The TC4 titanium alloy substrate is ultrasonically cleaned and dried, and then the titanium alloy substrate is transferred into an argon-protected laser cladding forming chamber through an intermediate chamber and placed above a forming base. The oxygen content of the forming chamber is ≤100 ppm; a 10 mm thick graphite felt is used between the titanium alloy substrate and the forming base for thermal insulation to reduce the cooling rate of laser directed energy deposition (L-DED) forming and reduce the concentration of thermal stress on the interface;

[0054] (3) Using 3D solid modeling software on a computer, establish a 3D solid model of the niobium intermediate layer and a 3D solid model of the aluminum alloy component;

[0055] (4) Importing the 3D solid model into the path planning and process setting software of the laser directed energy deposition (L-DED) forming equipment, setting the printing process parameters of the niobium intermediate layer and the aluminum alloy component respectively, and generating the printing path;

[0056] After importing the 3D solid model into the path planning and process setting software of the laser directed energy deposition (LDED) forming machine, the thickness of each deposition layer was set to 0.6 mm, the cladding head lift amount per layer was consistent with the deposition thickness, and the niobium powder feed rate was set to 15 g / min. A 45° reciprocating scanning strategy was adopted, with the scanning direction of adjacent layers rotated 90°.

[0057] The printing process parameters of the niobium intermediate layer are: laser power P is 1150 W, scanning speed v is 600 mm / min, and the spacing between two adjacent scanning passes is 100 mm / min. is 0.8 mm, and the interlayer cooling time t is 10 s;

[0058] The printing process parameters of the aluminum alloy component are: laser power P is 1100 W, scanning rate v is 600 mm / min, and the spacing between two adjacent scanning passes is 100 mm / min. The thickness is 0.8 mm and the interlayer cooling time t is 10 s.

[0059] (5) The first layer of niobium deposition with a thickness of 0.6 mm was first deposited on the titanium alloy substrate using the laser directed energy deposition process. During the deposition of the first layer of niobium deposition, the laser formed a molten pool at the Ti-Nb interface. The titanium alloy at the bottom of the molten pool melted and stirred with the niobium melt to form a Ti-Nb solid solution. Part of the titanium element diffused to the top of the molten pool, and finally formed a layer of Ti-Nb element gradient transition solid solution.

[0060] (6) A second niobium deposit layer is continuously deposited on the basis of the first niobium deposit layer, and the scanning direction of the cladding head is 90° to the first niobium deposit layer, and finally the Ti element in the upper portion of the second niobium deposit layer is further reduced to less than 5 atomic percent; the resulting two niobium deposit layers form a niobium intermediate layer with a total thickness of 1.2 mm;

[0061] (7) Printing aluminum alloy on the basis of the niobium intermediate layer, the Nb element below the aluminum alloy printing molten pool and the Al element in the aluminum alloy are fully fused, and a multi-layer phase structure composed of Nb2Al, NbAl3 and Nb3Si compounds is formed at the interface, specifically including the lower Nb-Al interface layer containing Nb2Al, NbAl3 and Nb3Si compounds, and the upper Nb-Al element diffusion layer containing NbAl3;

[0062] (8) Continue printing and forming according to the printing process parameters of the aluminum alloy component and the printing path generated by the software until the entire component is printed;

[0063] (9) The components formed by laser directed energy deposition are subjected to stress relief annealing to obtain a Ti / Al dissimilar metal integrated additive material based on the replacement of the niobium-based intermediate layer interface structure, which has two layers of niobium deposition layers.

[0064] Comparative Example 1

[0065] The other steps are the same as those in Example 1, except that the aluminum alloy is directly deposited on the titanium alloy substrate to print the aluminum alloy component, and the final product is a Ti / Al dissimilar alloy.

[0066] Comparative Example 2

[0067] The other steps are the same as those in Example 1, except that the deposition of the second niobium deposition layer in step (6) is not performed, and the aluminum alloy is directly printed on the basis of the first niobium deposition layer. The resulting Ti / Al dissimilar metal integrated additive material based on the replacement of the niobium-based intermediate layer interface structure has only one niobium deposition layer.

[0068] Test example:

[0069] 1. Observe the products obtained in Example 1, Comparative Example 2 and Comparative Example 1. Figure 2 As shown in (a), from right to left are samples without niobium deposition (obtained in Comparative Example 1), with one niobium deposition layer (obtained in Comparative Example 2), and with two niobium deposition layers (obtained in Example 1). It can be seen that the samples without niobium deposition and with one niobium deposition layer both have severe cracks at the interface, while the sample with two niobium deposition layers has a good interface bonding and forms a stable connection.

[0070] 2. The additive sample block deposited with two layers of niobium deposited in Example 1 was cut off together with the Ti alloy substrate by wire electrospark cutting, and then the metallographic specimen was prepared by inlaying, sandpaper grinding and polishing. The metallographic photograph under the optical microscope is shown as follows: Figure 2 As shown in (b), the Ti-Nb-Al interface forms a good metallurgical bond, and the interface composed of titanium alloy substrate-niobium intermediate layer-aluminum alloy presents a multi-layer structure: titanium alloy substrate → Nb-Ti solid solution zone (that is, the first niobium deposition layer) → second niobium deposition layer → Nb-Al interface layer → Nb-Al element diffusion layer → aluminum alloy.

[0071] Figure 3 The results of electron probe spectroscopy analysis on the element distribution of the interface layer of the additive sample obtained in Example 1 are as follows: Figure 3 The diffusion of Nb in the aluminum alloy can be seen in the upper parts of (b) and (c), further confirming the presence of a Nb-Al diffusion layer from the perspective of element distribution. It can also be seen that Ti and Nb are fused in the Nb-Ti solid solution zone, and that the second niobium deposit effectively prevents the diffusion of Ti into the Al alloy. This fully demonstrates that the niobium intermediate layer, which is formed by depositing two layers of niobium, can effectively block the interdiffusion of Ti and Al elements, preventing the formation of Ti-Al brittle intermetallic compounds, replacing them with Ti-Nb solid solutions, Nb-Al compounds, and other Nb-containing compounds.

[0072] Figure 4 (a) is a scanning electron microscope (SEM) microstructure photograph of the Nb-Al interface in the additive block obtained in Example 1. It can be clearly shown that a large number of dendrites are distributed in the Nb-Al element diffusion layer area, while finer grains are distributed at the Nb-Al interface closer to the niobium intermediate layer. Figure 4 The (b) and (c) areas in (a) are locally enlarged, showing that the (b) area is composed of a variety of irregularly distributed small island grains, while the (c) area is mainly composed of a large number of dendrite precipitations and aluminum alloy matrix.

[0073] The Nb-Al element diffusion layer in the additive sample obtained in Example 1 was analyzed by X-ray diffraction analysis (XRD). The results are as follows: Figure 5 As shown in (a), in addition to the Al and Si phases of the aluminum alloy matrix, the Nb-Al diffusion layer reacts to form the NbAl3 phase, which corresponds to the dendrite structure distributed in the SEM microstructure photograph. The electron backscatter diffraction (EBSD) analysis results of the Nb-Al interface layer show that in addition to the NbAl3 phase, the Nb-Al connection interface also reacts to form Nb2Al and Nb3Si phases on the side close to the Nb intermediate layer, as shown in Figure 2. Figure 5 As shown in (b1, b2).

[0074] The Vickers hardness of the Al-Nb-Ti double interface region of the additive sample obtained in Example 1 was measured using a microhardness tester. The sample was polished to a mirror finish before testing to ensure that the upper and lower surfaces of the sample were parallel. A load of 100 g was applied to different interface layer positions on the sample, and the load was maintained for 15 s. The same interface layer was tested 6 times at different positions, and the average value was taken as the final result. The Vickers hardness test results for different regions are shown in Figure 2. Figure 6 As shown, the average Vickers hardness of the Al alloy layer is 80.3 HV, primarily composed of Al and Al-Si eutectic phases. The average Vickers hardness of the Nb-Al diffusion layer is 281.7 HV, showing a significant increase in microhardness compared to the Al alloy layer, primarily due to the formation of a large amount of high-hardness NbAl₃ intermetallic compound phases. The average Vickers hardness of the Nb-Al interface layer is 694.7 HV, reaching its maximum Vickers hardness. This is primarily due to the formation of a large amount of NbAl₃ intermetallic compound phases and smaller amounts of Nb₂Al and Nb₃Si intermetallic compound phases. The greatest hardness improvement occurs in the multiphase interface. The average Vickers hardness of the second niobium deposit layer is 195.7 HV. The average Vickers hardness of the Nb-Ti solid solution zone (i.e., the first niobium deposit layer) is 271.3 HV. This region's microhardness lies between the Ti alloy layer and the Nb intermediate layer, demonstrating the complete solubility of Ti and Nb, forming a NbTi solid solution. The average Vickers hardness of the Ti alloy substrate region is 417.7 HV.

[0075] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A Ti / Al dissimilar metal integrated additive manufacturing method based on niobium-based intermediate layer interface structure replacement, characterized in that The method comprises the following steps: printing a multi-layer niobium deposition layer on the surface of a titanium alloy substrate by using a laser directed energy deposition process, and then printing an aluminum alloy layer on the surface of the niobium deposition layer by using a laser directed energy deposition process; The manufacturing method specifically includes the following steps: (1) Spherical pure niobium powder is prepared by plasma atomization, and spherical aluminum alloy powder is prepared by gas atomization or centrifugal atomization. The powder particle size distribution is 53~200μm. The powder is dried before printing; (2) The titanium alloy substrate is ultrasonically cleaned and dried, and then transferred into an argon-protected laser cladding forming chamber through an intermediate chamber and placed above a forming base. The oxygen content of the forming chamber is ≤100 ppm. A 5-10 mm thick graphite felt is used between the titanium alloy substrate and the forming base for thermal insulation to reduce the cooling rate of the laser directed energy deposition forming and reduce the concentration of thermal stress on the interface. (3) Using 3D solid modeling software, establish a 3D solid model of the niobium intermediate layer and a 3D solid model of the aluminum alloy component; (4) Importing the 3D solid model into the path planning and process setting software of the laser directed energy deposition forming equipment, setting the printing process parameters of the niobium intermediate layer and the aluminum alloy component respectively, and generating the printing path; (5) A layer of titanium alloy solid is first deposited on the surface of the titanium alloy substrate using a laser directed energy deposition process, and then a first layer of niobium deposition with a thickness of 300~600μm is deposited on the deposited titanium alloy solid. During the deposition of this first layer of niobium deposition, the laser forms a molten pool at the Ti-Nb interface. The titanium alloy at the bottom of the molten pool melts and stirs with the niobium melt to form a Ti-Nb solid solution. Part of the titanium element diffuses to the top of the molten pool, and finally forms a layer of Ti-Nb element gradient transition solid solution. (6) Continuing to deposit a second niobium deposition layer on the basis of the first niobium deposition layer, the scanning direction of the cladding head is 30° to 90° with respect to the first niobium deposition layer, and finally further reducing the atomic percentage of Ti element in the upper part of the second niobium deposition layer to below 5%; continuing to deposit the third to fifth niobium deposition layers in sequence on the basis of the second niobium deposition layer, or directly proceeding to the subsequent step (7); the resulting multi-layer niobium deposition layer forms a niobium intermediate layer with a total thickness of 0.6-3.0 mm; (7) Printing aluminum alloy on the basis of the niobium intermediate layer, the Nb element and the Al element in the aluminum alloy are fully fused below the aluminum alloy printing molten pool, and a multi-layered phase structure composed of Nb2Al, NbAl3 and other Nb-containing compounds is formed at the interface; (8) Continue printing and forming according to the printing process parameters and printing path of the aluminum alloy component until the entire component is printed; (9) The components formed by laser directed energy deposition are subjected to stress relief annealing to obtain Ti / Al dissimilar metal integrated additive materials based on the replacement of the niobium-based intermediate layer interface structure.

2. The Ti / Al dissimilar metal integrated additive manufacturing method based on niobium-based intermediate layer interface structure replacement according to claim 1, characterized in that: The titanium alloy substrate in step (2) is a titanium alloy with a grade of Ti-6Al-4V, TA15 or TC11.

3. The Ti / Al dissimilar metal integrated additive manufacturing method based on niobium-based intermediate layer interface structure substitution according to claim 1, characterized in that: After the three-dimensional solid model is imported into the path planning and process setting software of the laser directed energy deposition forming equipment in step (4), the thickness of each deposition layer is set to 0.3-0.6 mm, the lifting amount of each layer of the cladding head is consistent with the thickness of each deposition layer, and the powder feeding rate of niobium is set to 5-20 g / min and the powder feeding rate of aluminum alloy is set to 3-8 g / min.

4. The Ti / Al dissimilar metal integrated additive manufacturing method based on niobium-based intermediate layer interface structure replacement according to claim 1, characterized in that: The printing process parameters in step (4) are as follows: The printing process parameters of the niobium intermediate layer are: laser power P 1200 W~1800 W, scanning rate v The scanning speed is 350 mm / min~800 mm / min, and the scanning distance between two adjacent passes is 0.6mm~1.8mm, interlayer cooling time t 0~50s; The printing process parameters of the aluminum alloy component are: laser power P 800 W~1500 W, scanning rate v The scanning speed is 420 mm / min~840 mm / min, and the scanning interval between two adjacent passes is 0.6mm~1.8mm, interlayer cooling time t 0~60s.

5. The Ti / Al dissimilar metal integrated additive manufacturing method based on niobium-based intermediate layer interface structure replacement according to claim 1, characterized in that: The composition of the aluminum alloy in step (7) is AlSi 10 Mg or other aluminum-silicon alloys or high-strength aluminum alloys; the multi-layered phase structure includes a lower Nb-Al interface layer containing Nb2Al, NbAl3 and other Nb-containing compounds, and an upper Nb-Al diffusion layer containing NbAl3.

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