Laser powder feeding additive manufacturing device and method for Nb-Si intermetallic compound composite material

Abstract

The invention discloses a laser powder feeding additive manufacturing device and method for an Nb-Si intermetallic compound composite material, and relates to the technical field of high-temperature structural material additive manufacturing. The method solves the problems that according to an existing method for preparing the Nb-Si intermetallic compound composite material through the laser directional energy deposition technology, due to the fact that the local temperature gradient is huge and thermal stress is too high, a formed part is prone to cracking, deformation and composition segregation, and a complete and compact component cannot be obtained. In an inert gas protection environment, dynamic preheating and post-heating heat preservation are carried out on the front area and the rear area of a laser molten pool through combination of overall preheating of a substrate and a local auxiliary heating device synchronously moving with a laser deposition head, and the temperature gradient of a deposition area is strictly controlled to be below a safety threshold value through infrared temperature measurement closed-loop control; and finally, stress release is completed through programmed slow cooling. The method is used for crack-free and high-quality near-net forming manufacturing of Nb-Si-based intermetallic compound composite material components for high-temperature structures in the aerospace field.

Description

Technical Field

[0001] This invention relates to the field of additive manufacturing technology for high-temperature structural materials, specifically to a laser additive manufacturing method and equipment for preparing high-temperature structural components of Nb-Si-based intermetallic compound composite materials. In particular, it relates to a powder-feed additive manufacturing process based on laser-directed energy deposition (LDED) supplemented by synchronous thermal field management. Background Technology

[0002] Nb-Si based composite materials, with their superior temperature resistance, high specific strength, and excellent creep resistance compared to traditional nickel-based superalloys, have become ideal candidate materials for hot-end components in next-generation aero-engines and other thermodynamic equipment. However, the inherent high melting point and significant room-temperature brittleness of this material system pose significant challenges to its processing and forming.

[0003] Currently, traditional smelting and casting processes remain the primary method for preparing Nb-Si based composites. While this process can produce bulk materials, the solidification process is difficult to control, often resulting in coarse microstructures and severe segregation, particularly the formation of coarse lath-like or dendritic primary silicide phases (such as Nb5Si3). These coarse, brittle phases become crack initiation sites, leading to extremely low room-temperature fracture toughness in as-cast Nb-Si based alloys, almost lacking the basic damage tolerance required for structural applications. Furthermore, the subsequent machinability of the ingots is extremely poor, and this poor machinability prevents Nb-Si based alloys from being used to produce complex components through conventional machining, severely limiting their engineering applications.

[0004] Laser-directed energy deposition (LDED), as an advanced additive manufacturing technology, offers a new approach for near-net-shape forming of complex Nb-Si-based components. Theoretically, it can achieve near-net-shape forming of complex Nb-Si-based components. However, in practical applications, due to the concentrated energy and extremely rapid heating and cooling rates of laser processing, severe temperature gradients and enormous thermal stresses are generated within the material. For Nb-Si, a highly brittle material, these enormous thermal stresses can easily lead to severe cracking or even fragmentation of the formed part during manufacturing or after cooling, making it impossible to obtain a complete, usable component.

[0005] Although substrate preheating is a common method to alleviate thermal stress and can alleviate the problem to some extent, for components with large size or complex geometry, single global preheating is difficult to completely eliminate excessive temperature gradients in local areas (such as thin walls and corners). Cracks remain an insurmountable core technical bottleneck restricting the molding of high-quality Nb-Si based composite materials using LDED technology. Summary of the Invention

[0006] The purpose of this invention is to address the problems of existing methods for preparing Nb-Si intermetallic compound composites using laser-directed energy deposition technology, which suffer from the tendency of the formed parts to crack, deform, and segregate due to large local temperature gradients and excessive thermal stress, making it impossible to obtain complete and dense components. Therefore, this invention provides a laser powder feeding additive manufacturing device and method for Nb-Si intermetallic compound composites.

[0007] The technical solution of this invention is:

[0008] A laser powder feeding additive manufacturing apparatus for Nb-Si intermetallic compound composite materials includes:

[0009] A protective chamber, used to provide an inert gas protective environment;

[0010] The substrate heating system 3 is located in the protective chamber and is used to preheat and fix the substrate 4.

[0011] A laser deposition system includes a laser, a laser deposition head 2 connected to the laser's optical path, and a laser deposition head motion mechanism 6 that drives the laser deposition head 2 to move; the laser deposition head 2 integrates an optical system 8 for conducting and focusing the laser beam output from the laser.

[0012] The powder feeding system includes a powder feeder for storing Nb-Si alloy powder and a powder feeding hose 7. The powder feeder is connected to the laser deposition head 2 through the powder feeding hose 7 and is used to deliver Nb-Si alloy powder to the focal region of the laser deposition head 2.

[0013] A local auxiliary heating device 1 is mounted on the laser deposition head motion mechanism 6 via a local auxiliary heating device bracket 10. The local auxiliary heating device 1 includes a local auxiliary heating device motion mechanism 9 and an induction heating coil 11 mounted on its output end via a local auxiliary heating device fixing assembly 12. The induction heating coil 11 is constructed as an open structure and moves synchronously with the laser deposition head 2 to dynamically heat the area near the focal point of the laser deposition head 2.

[0014] Furthermore, the powder feeding system is a multi-channel powder feeder, which can independently control the powder feeding rate of different elements or pre-alloyed powders.

[0015] Furthermore, the device also includes a central control system and an infrared temperature measuring device connected thereto, for real-time monitoring of the temperature of the deposition area and closed-loop adjustment of the output power of the induction heating coil 11.

[0016] A laser powder feeding additive manufacturing method for Nb-Si intermetallic compound composite materials, employing the aforementioned laser powder feeding additive manufacturing apparatus for Nb-Si intermetallic compound composite materials, is characterized by comprising the following steps:

[0017] Step 1: Preparations before additive manufacturing:

[0018] Select a niobium alloy or titanium alloy substrate 4 that matches the thermophysical properties of the material to be prepared, clean it, and then fix it on a heatable worktable.

[0019] Prepare Nb-Si alloy powder with a specific particle size distribution and place it in a powder feeder, ensuring that the powder feeding system is dry and airtight;

[0020] Based on the three-dimensional model of the part, plan the laser scanning path, layer thickness, and overlap rate process parameters;

[0021] Step 2, Shaping and Deposition:

[0022] The workbench with the substrate 4 fixed on it is placed in a protective chamber filled with high-purity inert gas to ensure that the oxygen and moisture content in the environment are both below 15 ppm; the substrate heating system 3 is started to preheat the entire substrate 4 to 1000℃~1400℃ and keep it at that temperature.

[0023] The laser, powder feeder, and local auxiliary heating device 1 that move synchronously with the laser deposition head 2 of the laser deposition system are activated to begin layer-by-layer additive manufacturing.

[0024] The process parameters are controlled as follows: laser power 3000W~4000W, laser spot diameter 2mm~5mm, powder feeding rate 10g / min~20g / min, cladding speed 10mm / s~20mm / s, and single-layer deposition thickness 0.8mm~2.0mm.

[0025] Step 3: Synchronous Local Thermal Management:

[0026] By using an induction heating coil 11 that moves synchronously with the laser deposition head 2, the area in front of the laser cladding point is dynamically preheated, and the solidified area behind the laser cladding point is post-heated, thereby forming a moving thermal field with a gentle temperature gradient around the deposition point. At the same time, the temperature of the deposition area is monitored in real time in a non-contact manner by an infrared temperature measuring device, and this temperature is used as a feedback signal to control the output power of the induction heating coil 11 in a closed loop, so that the temperature gradient of the deposition area and the nearby heat-affected zone is strictly controlled below a preset safety threshold, thereby suppressing the accumulation of thermal stress and the initiation of cracks.

[0027] Step 4, slow cooling treatment: The substrate heating system 3 and the local auxiliary heating device 1 are coordinated to slowly cool the Nb-Si intermetallic compound composite material molded part 5 to below 600°C at a programmed cooling rate of no more than 5°C / min in order to release stress.

[0028] Furthermore, in step one, a multi-channel powder feeder is used to fill powders of each alloy element separately. By adjusting the powder feeding rate ratio of different channels in real time during the deposition process, a gradual change in composition along the height direction of the component is achieved, thereby preparing functionally graded materials.

[0029] Furthermore, in step two, the overall preheating temperature of the substrate 4 is set according to the brittle-ductile transition temperature of the Nb-Si intermetallic compound composite material, and the preheating temperature is 1200℃±100℃.

[0030] Furthermore, in step two, the laser beam adopts a swing scanning mode to increase the size of the molten pool, promote the full progress of the metallurgical reaction, and improve the uniformity of composition and structure; the swing scanning mode is circular swing or linear swing.

[0031] Furthermore, in step three, the induction heating coil 11 has an open structure so as to surround the deposition area without interfering with the laser beam and powder beam; the open structure is a C-shaped structure.

[0032] Furthermore, in step three, the temperature gradient of the deposition zone and the nearby heat-affected zone is controlled below 100 K / mm.

[0033] Furthermore, in step two, the substrate 4 is preheated to 1200℃±100℃, the laser power is 3500~4000W, the powder feeding rate is 15~20g / min, and the cladding speed is 15~20mm / s.

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] 1. This invention can fundamentally suppress manufacturing cracks and achieve high-quality forming. By combining a dual thermal management strategy of "overall substrate preheating" and "synchronous moving local induction heating", a dynamically balanced thermal field is formed in the laser molten pool area, controlling the temperature gradient and thermal stress of the deposition process within a safe range. This mechanism avoids the generation of macroscopic cracks and obtains high-density, defect-free formed parts.

[0036] 2. This invention can significantly refine the microstructure and comprehensively improve the material properties. Thanks to the precisely controlled rapid melting and solidification process, the prepared Nb-Si based composite material has a uniform and fine microstructure, forming a dispersed Nbss solid solution and Nb5Si3 silicide composite structure, effectively avoiding the formation of coarse and brittle phases. Therefore, the mechanical properties of the material, such as room temperature fracture toughness and high temperature strength, are significantly improved.

[0037] 3. This invention possesses near-net-shape forming capability for complex components, with high process stability and flexibility. This method can stably fabricate large-sized, geometrically complex components, overcoming the technical bottleneck that prevents the manufacture of complex parts using traditional processes due to the intrinsic brittleness and machinability of Nb-Si materials. The synchronous auxiliary heating system can adapt to complex scanning paths, providing targeted thermal management for areas with different geometric features (such as thin walls and corners), ensuring the stability of overall forming quality and process flexibility.

[0038] 4. This invention enables active control of composition and performance to manufacture functionally graded materials. By combining multi-channel powder feeding technology and adjusting the powder feeding rate in real time during the deposition process, the chemical composition of the component can be continuously and gradually changed along a specific direction (such as the height direction), thereby manufacturing functionally graded components with a smooth transition from a tough matrix to a high-temperature composite material and performance designed as needed. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the overall structure of the high-quality additive manufacturing equipment for preparing Nb-Si intermetallic compound composites according to the present invention;

[0040] Figure 2 This is a schematic diagram of the local auxiliary heating device described in this invention;

[0041] Figure 3 These are macroscopic morphology photographs of the Nb-Si intermetallic compound composite material bulk prepared in Example 1 of this invention;

[0042] Figure 4 These are macroscopic morphological photographs of the cross-section and longitudinal section of the Nb-Si intermetallic compound composite material block prepared in Example 1 of this invention;

[0043] Figure 5 This is a comparison diagram of the microstructure of the materials prepared in Embodiment 1 (additive manufacturing) and Comparative Example 1 (conventional casting) of the present invention;

[0044] In the figure: 1. Local auxiliary heating device; 2. Laser deposition head; 3. Substrate heating system; 4. Substrate; 5. Nb-Si intermetallic compound composite material molded part; 6. Laser deposition head motion mechanism; 7. Powder feeding hose; 8. Optical system; 9. Local auxiliary heating device motion mechanism; 10. Local auxiliary heating device bracket; 11. Induction heating coil; 12. Local auxiliary heating device fixing assembly. Detailed Implementation

[0045] Specific implementation method one: Combining Figure 1 and Figure 2 This embodiment describes a laser powder feeding additive manufacturing apparatus for Nb-Si intermetallic compound composite materials, comprising:

[0046] A protective chamber, used to provide an inert gas protective environment;

[0047] The substrate heating system 3 is located in the protective chamber and is used to preheat and fix the substrate 4.

[0048] The laser deposition system includes a laser, a laser deposition head 2 connected to the laser's optical path, and a laser deposition head motion mechanism 6 that drives the laser deposition head 2. During the LDED process, the laser deposition head prints at different positions through continuous movement, and each LDED device's laser deposition head has its own motion mechanism. The laser deposition head 2 integrates an optical system 8 for guiding and focusing the laser beam output from the laser; the optical system 8 is also integrated into the LDED device.

[0049] The powder feeding system includes a powder feeder for storing Nb-Si alloy powder and a powder feeding hose 7. The powder feeder is connected to the laser deposition head 2 through the powder feeding hose 7 and is used to deliver Nb-Si alloy powder to the focal region of the laser deposition head 2.

[0050] A local auxiliary heating device 1 is mounted on the laser deposition head motion mechanism 6 via a local auxiliary heating device bracket 10. The local auxiliary heating device 1 includes a local auxiliary heating device motion mechanism 9 and an induction heating coil 11 mounted at its output end via a local auxiliary heating device fixing assembly 12. The induction heating coil 11 is constructed with an open structure and moves synchronously with the laser deposition head 2 to dynamically heat the area near the focal point of the laser deposition head 2. With this configuration, the device achieves dynamic thermal management under an inert gas protective environment through the synergistic effect of various systems, ensuring effective control of the temperature gradient.

[0051] The induction heating coil 11 is constructed with an open structure, such as a C-shape. The local auxiliary heating device is not rigidly connected to the laser deposition head; it is movable. The movement involves changing the opening direction of the C-shaped structure so that the opening always faces the deposition direction. Therefore, the local auxiliary heating device fixing assembly 12 is not rigidly connected to the laser deposition head, but it is rigidly connected to the other components of the local auxiliary heating device.

[0052] Specific Implementation Method Two: Combining Figure 1 and Figure 2 This embodiment describes a multi-channel powder feeder that can independently control the feeding rate of different elements or pre-alloyed powders. This configuration allows for precise real-time adjustment of the molten pool composition during manufacturing by independently controlling the feeding rate of each element's powder, providing crucial technical support for the preparation of functionally graded materials. Other components and connections are the same as in Specific Embodiment One.

[0053] Specific implementation method three: Combining Figure 1 and Figure 2 This embodiment further includes a central control system and an infrared temperature measuring device connected thereto, used to monitor the temperature of the deposition area in real time and to adjust the output power of the induction heating coil 11 in a closed-loop manner. This configuration, through the combination of infrared temperature measurement and closed-loop control, achieves precise dynamic control of the moving thermal field, ensuring that the temperature gradient is maintained within a safe threshold in deposition areas with different geometric features, greatly improving process stability and repeatability. Other components and connections are the same as in specific embodiments one or two.

[0054] Specific implementation method four: Combination Figures 1 to 5 This embodiment describes a laser powder feeding additive manufacturing method for Nb-Si intermetallic compound composite materials, employing the aforementioned laser powder feeding additive manufacturing apparatus for Nb-Si intermetallic compound composite materials. The method is characterized by the following steps:

[0055] Step 1: Preparations before additive manufacturing:

[0056] Select a niobium alloy or titanium alloy substrate 4 that matches the thermophysical properties of the material to be prepared, clean it, and then fix it on a heatable worktable.

[0057] Prepare Nb-Si alloy powder with a specific particle size distribution and place it in a powder feeder, ensuring that the powder feeding system is dry and airtight;

[0058] Based on the three-dimensional model of the part, plan the laser scanning path, layer thickness, and overlap rate process parameters;

[0059] Step 2, Shaping and Deposition:

[0060] The workbench with the substrate 4 fixed on it is placed in a protective chamber filled with high-purity inert gas to ensure that the oxygen and moisture content in the environment are both below 15 ppm; the substrate heating system 3 is started to preheat the entire substrate 4 to 1000℃~1400℃ and keep it at that temperature.

[0061] The laser, powder feeder, and local auxiliary heating device 1 that move synchronously with the laser deposition head 2 of the laser deposition system are activated to begin layer-by-layer additive manufacturing.

[0062] The process parameters are controlled as follows: laser power 3000W~4000W, laser spot diameter 2mm~5mm, powder feeding rate 10g / min~20g / min, cladding speed 10mm / s~20mm / s, and single-layer deposition thickness 0.8mm~2.0mm.

[0063] Step 3: Synchronous Local Thermal Management:

[0064] By using an induction heating coil 11 that moves synchronously with the laser deposition head 2, the area in front of the laser cladding point is dynamically preheated, and the solidified area behind the laser cladding point is post-heated, thereby forming a moving thermal field with a gentle temperature gradient around the deposition point. At the same time, the temperature of the deposition area is monitored in real time in a non-contact manner by an infrared temperature measuring device, and this temperature is used as a feedback signal to control the output power of the induction heating coil 11 in a closed loop, so that the temperature gradient of the deposition area and the nearby heat-affected zone is strictly controlled below a preset safety threshold, thereby suppressing the accumulation of thermal stress and the initiation of cracks.

[0065] Step 4, slow cooling treatment: The substrate heating system 3 and the local auxiliary heating device 1 are coordinated to slowly cool the Nb-Si intermetallic compound composite material molded part 5 to below 600°C at a programmed cooling rate of no more than 5°C / min in order to release stress.

[0066] This invention utilizes a high-power laser as a heat source in an inert gas protected environment, combined with a localized auxiliary heating system that moves synchronously with the laser deposition head. By dynamically preheating and slowly cooling the areas before and after the molten pool, the temperature gradient during deposition is significantly reduced, effectively suppressing hot cracking. This method can stably manufacture large-size Nb-Si-based composite material components with uniform composition, dense microstructure, and no macroscopic cracks, providing a feasible manufacturing approach for the application of this material in aerospace and other fields.

[0067] Specific Implementation Method Five: Combining Figures 1 to 5This embodiment describes a method where, in step one, a multi-channel powder feeder is used to separately fill powders of each alloy element. By adjusting the powder feeding rate ratio of different channels in real time during the deposition process, a gradual change in composition along the height of the component is achieved, thereby preparing a functionally graded material. This setup, by independently controlling the powder feeding rate of each element, allows for precise real-time adjustment of the molten pool composition during manufacturing, providing a crucial technical feasibility for preparing functionally graded materials with performance distribution as needed, overcoming the limitations of single-material properties. Other components and connections are the same as in specific embodiments one, two, three, or four.

[0068] Specific Implementation Method Six: Combination Figures 1 to 5 In this embodiment, in step two, the overall preheating temperature of the substrate 4 is set based on the brittle-ductile transition temperature of the Nb-Si intermetallic compound composite material, and is 1200℃±100℃. This setting, preheating the substrate to above the brittle-ductile transition temperature of the material, significantly reduces the temperature difference between the deposited layer and the substrate, reducing thermal stress on a global scale, laying the foundation for subsequent localized thermal management, and effectively preventing macroscopic deformation and interlayer cracking. Other components and connections are the same as in specific embodiments one, two, three, four, or five.

[0069] Specific implementation method seven: Combination Figures 1 to 5 In this embodiment, step two involves a oscillating scanning mode of the laser beam to increase the size of the molten pool, promote the full metallurgical reaction, and improve the uniformity of composition and structure. The oscillating scanning mode can be circular or linear. This configuration effectively expands the molten pool area and prolongs the existence time of the liquid metal, which not only facilitates the full melting of powder and gas escape, reducing porosity, but also promotes uniform diffusion of elements, thereby significantly improving the compositional uniformity and structural density of the formed part. Other components and connections are the same as in specific embodiments one, two, three, four, five, or six.

[0070] Specific implementation method eight: Combination Figures 1 to 5 In this embodiment, in step three, the induction heating coil 11 has an open structure to surround the deposition area without interfering with the laser beam and powder stream; the open structure is C-shaped. This configuration allows the open (e.g., C-shaped) induction coil to surround the molten pool area from the side without physical interference with the laser beam and powder stream above, achieving precise, non-contact heating of the area in front of and behind the molten pool, ensuring the feasibility and effectiveness of local thermal field management. Other components and connections are the same as in specific embodiments one, two, three, four, five, six, or seven.

[0071] Specific Implementation Method Nine: Combining Figures 1 to 5In this embodiment, step three involves controlling the temperature gradient of the deposition zone and its adjacent heat-affected zone below 100 K / mm. This strict control of the temperature gradient within the deposition zone to below this critical threshold of 100 K / mm is crucial to ensuring that the instantaneous thermal stress remains below the material's fracture strength. This directly inhibits the initiation and propagation of microcracks, providing a core guarantee for achieving crack-free forming. Other components and connections are the same as in specific embodiments one, two, three, four, five, six, seven, or eight.

[0072] Specific Implementation Method Ten: Combining Figures 1 to 5 In this embodiment, in step two, the substrate 4 is preheated to 1200℃±100℃, the laser power is 3500~4000W, the powder feeding rate is 15~20g / min, and the cladding speed is 15~20mm / s. This parameter setting (substrate preheating 1200℃±100℃, laser power 3500~4000W, powder feeding rate 15~20g / min, cladding speed 15~20mm / s) constitutes the optimal process window for achieving high-quality forming. It maintains appropriate heat input and deposition efficiency while ensuring sufficient powder melting and good metallurgical bonding, making it a key process combination for obtaining dense, defect-free, and uniformly structured parts. Other components and connections are the same as in embodiments one, two, three, four, five, six, seven, eight, or nine.

[0073] Example 1

[0074] This embodiment provides a detailed method for preparing Nb-Si intermetallic compound composite material bulk materials using a "global high preheating + synchronous local thermal management" strategy.

[0075] Step 1: Preparation before additive manufacturing: First, select a pure titanium substrate with dimensions of 150mm × 80mm × 15mm. Clean the substrate ultrasonically with acetone and anhydrous ethanol sequentially to remove surface oil. After drying, place it on a heated workbench. Second, prepare Nb-22Ti-16Si-5Cr-3Al-2Hf (atomic percentage) alloy spherical powder using a gas atomization method. The particle size distribution is D10 = 55μm, D50 = 75μm, and D90 = 110μm. Dry the powder in a vacuum oven at 120℃ for 4 hours to remove adsorbed moisture. Then, load it into a dry, airtight powder feeder, ensuring the powder feeding system is dry and airtight. Finally, based on a 40mm × 35mm × 35mm cubic 3D model, plan the laser scanning path using a reciprocating scanning strategy, setting the single-layer thickness to 1.0mm and the inter-channel overlap rate to 40%.

[0076] Step 2, Molding Parameter Control and Deposition: The worktable containing the substrate is placed in a protective chamber filled with high-purity argon gas. A gas circulation purification system ensures that the oxygen and moisture content within the chamber are both below 15 ppm. The substrate heating system is activated, preheating the pure titanium substrate to 1200℃ and holding it at that temperature for 30 minutes to reduce the temperature gradient during subsequent deposition. Then, the high-power fiber laser, powder feeder, and local auxiliary heating device that moves synchronously with the laser deposition head are activated to begin layer-by-layer additive manufacturing. Specific process parameters are set as follows: laser power 3500W, laser spot diameter 4mm, powder feed rate 15g / min, and cladding speed 15mm / s.

[0077] Step 3: Synchronous Local Thermal Management and Process Control: Throughout the deposition process, a C-shaped induction heating coil (this open structure avoids interference with the laser beam and powder beam) moves synchronously with the laser deposition head. This coil dynamically preheats the area to be scanned in front of the laser cladding point and provides post-heat preservation to the area that has just solidified behind it. A non-contact, real-time infrared thermometer monitors the temperature of the deposition area and uses the temperature signal as feedback to strictly control the temperature gradient of the deposition area and the nearby heat-affected zone below the safe threshold of 100 K / mm, thereby effectively suppressing the accumulation of thermal stress and the initiation of thermal cracks.

[0078] Step 4: Slow Cooling Treatment and Performance Characterization: After the cubic bulk additive manufacturing process is completed, the substrate heating system and local auxiliary heating system are coordinated to slowly cool the entire formed part to below 600°C at a programmed cooling rate of 5°C / min to complete stress release. The heating system is then turned off, allowing it to cool to room temperature in a protective atmosphere. The final obtained Nb-Si based composite bulk (e.g., Figure 3 As shown), its surface morphology is good, with no macroscopic cracks visible to the naked eye. After wire EDM, its cross-section and longitudinal section (as shown) are... Figure 4 All (as shown) exhibit good density, free from metallurgical defects such as cracks and porosity. Metallographic analysis reveals that their microstructure is as follows: Figure 5 As shown, the microstructure is fine and uniform, mainly composed of Nbss solid solution and Nb5Si3 silicide phases, avoiding the coarse, lamellar primary silicides commonly found in traditional casting processes. A sample was cut from this block and subjected to a three-point bending test, revealing a room temperature fracture toughness of 22.16 MPa·m1 / 2.

[0079] Example 2

[0080] This embodiment aims to prepare a functionally graded component of Nb-Si intermetallic compound composite material with a compositional gradient. The main equipment and environmental control are the same as in Embodiment 1.

[0081] Step 1: Preparation before additive manufacturing: The selection and treatment of the substrate are the same as in Example 1. This example uses a four-channel powder feeder. Channel 1 is filled with pure Nb powder with an average particle size of 70 μm, channel 2 with pure Ti powder with an average particle size of 45 μm, channel 3 with pure Si powder with an average particle size of 30 μm, and channel 4 with Cr-Al-Hf pre-alloyed powder with an average particle size of 60 μm. All powders undergo thorough vacuum drying.

[0082] Step 2, Molding Parameter Control and Deposition: In the initial deposition height range of 0–5 mm, the feed rates of Nb and Ti powders were increased through programmed control, while the feed rate of Si powder was decreased to form a Nb / Ti-rich transition layer rich in the toughening phase Nbss, ensuring good bonding between the bottom of the component and the substrate and high toughness. Subsequently, in the height range of 5 mm to 30 mm, the feed rates of each powder channel were smoothly adjusted to the nominal composition (Nb-22Ti-16Si-5Cr-3Al-2Hf) ratio and kept stable. During the deposition process, the laser beam adopted a circular oscillating scanning mode with a frequency of 50 Hz and an amplitude of 1 mm. This mode increased the size and life of the molten pool, promoted the uniform mixing and metallurgical reaction of powders from different sources, and further improved the uniformity of the microstructure. The remaining parameters, simultaneous thermal management, and slow cooling process were the same as in Example 1.

[0083] Comparative Example 1

[0084] This comparative example uses a traditional vacuum non-consumable arc melting casting process to prepare Nb-Si intermetallic compound composite materials with the same nominal composition as in Example 1.

[0085] Step 1, Smelting and Casting: High-purity Nb, Ti, Si, Cr, Al, and Hf metal raw materials are precisely proportioned according to the nominal composition in Example 1 and placed in a vacuum non-consumable arc melting furnace. To ensure uniform composition, the alloy ingot is repeatedly turned and melted on a water-cooled copper crucible at least 5 times.

[0086] Step 2, Results and Characterization: Observation of the microstructure of the as-cast alloy revealed that its microstructure was coarse and severely heterogeneous, containing a large number of primary Nb5Si3 silicide phases distributed in coarse lath and network patterns. These coarse brittle phases are the initiation points of cracks, consistent with the description in the background section (e.g., Figure 5 (As shown). Samples were painstakingly cut from a few relatively intact areas and subjected to three-point bending tests. The average room-temperature fracture toughness was measured to be only 13.68 MPa·m. 1 / 2 The results show that traditional casting processes have difficulty controlling the solidification structure and suppressing cracks, and the mechanical properties of the prepared materials are far lower than those of the materials prepared by the method of this invention.

[0087] Working principle

[0088] Combination Figures 1 to 5 The working principle of the laser powder feeding additive manufacturing device and method for Nb-Si intermetallic compound composite materials described in this invention is explained as follows: The core of the method described in this invention lies in the innovative combination of high-power laser melting, inert gas protection and synchronous mobile local induction heating, forming a multi-level thermal control strategy of "global preheating + synchronous local dynamic thermal management + programmed slow cooling".

[0089] This strategy constructs a dynamically balanced thermal field through the synergistic effect of overall substrate preheating and synchronous moving local induction heating. As the laser deposition head 2 deposits layer by layer, the induction heating coil 11 in front of it dynamically preheats the area to be scanned, reducing the temperature difference between the material and the molten pool; the coil behind it provides post-heating insulation to the just-solidified area, reducing the cooling rate. This continuous process of "preheating-melting-slow cooling" creates a moving local thermal field with a gentle temperature gradient around the laser's point of action.

[0090] Meanwhile, a closed loop consisting of an infrared temperature measuring device and a central control system monitors the temperature of the deposition area in real time and provides feedback to control the power of the induction heating coil 11, ensuring that the temperature gradient of the moving thermal field is strictly controlled below a safe threshold (e.g., 100 K / mm). During this process, the overall high-temperature environment provided by the substrate heating system 3 further reduces global thermal stress.

[0091] This multi-level thermal control strategy systematically solves the problem of thermal stress accumulation in laser additive manufacturing of Nb-Si materials, controlling the peak thermal stress below the material's fracture strength, thereby fundamentally avoiding the generation of thermal cracks and ultimately achieving high-quality forming with crack-free, highly dense, and uniform microstructure.

[0092] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A laser powder-fed additive manufacturing apparatus for Nb-Si intermetallic compound composites, characterized by, It comprises: A protection chamber for providing an inert gas protection environment; A substrate heating system (3) arranged in the protection chamber for preheating and fixing a substrate (4); A laser deposition system comprising a laser, a laser deposition head (2) connected with the laser in an optical path, and a laser deposition head movement mechanism (6) for driving the movement of the laser deposition head (2); the laser deposition head (2) is internally integrated with an optical system (8) for conducting and focusing the light beam output by the laser; A powder feeding system comprising a powder feeder for storing Nb-Si alloy powder and a powder feeding hose (7), the powder feeder being connected with the laser deposition head (2) through the powder feeding hose (7) for feeding Nb-Si alloy powder to the focal point area of the laser deposition head (2); A local auxiliary heating device (1) mounted on the laser deposition head movement mechanism (6) through a local auxiliary heating device support (10); the local auxiliary heating device (1) comprises a local auxiliary heating device movement mechanism (9) and an induction heating coil (11) mounted on the output end thereof through a local auxiliary heating device fixing assembly (12); the induction heating coil (11) is configured in an open structure and moves synchronously with the laser deposition head (2) to dynamically heat the area near the focal point of the laser deposition head (2).

2. The laser powder-fed additive manufacturing apparatus of Nb-Si intermetallic compound composites of claim 1, wherein, The powder feeding system is a multi-channel powder feeder capable of independently controlling the powder feeding rate of different element or pre-alloy powders.

3. The laser powder-fed additive manufacturing apparatus of Nb-Si intermetallic compound composites of claim 1, wherein, The device further comprises a central control system and an infrared temperature measuring device connected thereto for real-time monitoring of the deposition area temperature and closed-loop adjustment of the output power of the induction heating coil (11).

4. A laser powder feeding additive manufacturing method of an Nb-Si intermetallic compound composite material, using the laser powder feeding additive manufacturing apparatus of the Nb-Si intermetallic compound composite material according to any one of claims 1 to 3, characterized by, It comprises the following steps: Step one, preparation before additive manufacturing: Select a niobium alloy or titanium alloy substrate (4) matched with the thermal physical properties of the material to be prepared, clean it after cleaning treatment, and fix it on a heatable workbench; Prepare Nb-Si alloy powder with a specific particle size distribution and place it in the powder feeder, ensuring that the powder feeding system is dry and airtight; According to the three-dimensional model of the part, plan the laser scanning path, layer thickness and overlap rate process parameters; Step two, forming and deposition: Place the workbench with the substrate (4) fixed therein in the protection chamber filled with high-purity inert gas to ensure that the oxygen content and moisture content in the environment are both lower than 15ppm; start the substrate heating system (3) to preheat the substrate (4) as a whole to 1000℃~1400℃ and keep it warm; Start the laser of the laser deposition system, the powder feeder, and the local auxiliary heating device (1) moving synchronously with the laser deposition head (2) to start layer-by-layer additive manufacturing; Among them, the process parameters are controlled as follows: laser power 3000W~4000W, laser spot diameter 2mm~5mm, powder feeding rate 10g / min~20g / min, cladding speed 10mm / s~20mm / s, single layer deposition thickness 0.8mm~2.0mm; Step three, synchronous local thermal management: A induction heating coil (11) synchronously moves with the laser deposition head (2), and a region in front of the laser cladding point is dynamically preheated, and a solidified region behind the laser cladding point is post-heated, so as to form a moving heat field with a gentle temperature gradient around the deposition point; meanwhile, an infrared temperature measuring device non-contactly monitors the temperature of the deposition region in real time, and the temperature is taken as a feedback signal to close-loop control the output power of the induction heating coil (11), so that the temperature gradient of the deposition region and the nearby heat affected zone is strictly controlled below a preset safety threshold, thereby inhibiting the accumulation of thermal stress and the initiation of cracks. Step four, slow cooling treatment: cooperatively control the substrate heating system (3) and the local auxiliary heating device (1), and slowly cool the Nb-Si intermetallic compound composite material forming piece (5) as a whole to below 600 DEG C at a programmed cooling rate of not more than 5 DEG C / min, so as to release stress.

5. The laser powder-fed additive manufacturing method of an Nb-Si intermetallic compound composite material according to claim 4, wherein, In the step one, a multi-channel powder feeder is used to fill alloy element powders, and the composition gradient along the height direction of the component is realized by adjusting the powder feeding rate ratio of different channels in real time during the deposition process, so as to prepare a functional gradient material.

6. The laser powder-fed additive manufacturing method of Nb-Si intermetallic compound composites of claim 4, wherein, In the step two, the overall preheating temperature of the substrate (4) is set according to the brittle-ductile transition temperature of the Nb-Si intermetallic compound composite material, and the preheating temperature is 1200 DEG C±100 DEG C.

7. The laser powder-fed additive manufacturing method of Nb-Si intermetallic compound composites of claim 4, wherein, In the step two, the laser beam adopts a swing scanning mode to increase the size of the molten pool, promote the full progress of the metallurgical reaction, and improve the uniformity of the composition and the organization; the swing scanning mode is circular swing or linear swing.

8. The laser powder-fed additive manufacturing method of Nb-Si intermetallic compound composites of claim 4, wherein, In the step three, the induction heating coil (11) is of an open structure to surround the deposition region without interfering with the laser beam and the powder beam; the open structure is a C-shaped structure.

9. The laser powder-fed additive manufacturing method of Nb-Si intermetallic compound composites of claim 4, wherein, In the step three, the temperature gradient of the deposition region and the nearby heat affected zone is controlled to be below 100K / mm.

10. The laser powder-fed additive manufacturing method of an Nb-Si intermetallic compound composite according to any one of claims 4 to 9, characterized in that, In the step two, the substrate (4) is preheated to 1200 DEG C±100 DEG C, the laser power is 3500-4000W, the powder feeding rate is 15-20g / min, and the cladding speed is 15-20mm / s.

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