Manufacturing method of intermetallic compound thin-wall special-shaped component with gradient performance

Abstract

The invention belongs to the technical field of metal layered gradient composite materials, and discloses a manufacturing method of an intermetallic compound thin-wall special-shaped component with gradient performance, which comprises the following steps of: designing the gradient performance of the component; component material distribution is determined; the component material ratio is determined; designing a metal wire weaving scheme; weaving metal wires; low-melting-point metal die casting; hot pressed sintering; and post-processing the blank. According to the manufacturing method, the three-dimensional weaving technology and the die casting technology are combined, the component with the gradient performance can be directly prepared, and the complex service conditions are met. According to the manufacturing method, the three-dimensional weaving process and the die-casting process are combined, the final component shape is directly obtained, the forming problem of brittle intermetallic compounds and gradient materials is solved, the technological process is simple, and the part quality is reliable.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal laminated gradient composite materials, and relates to a manufacturing method for an intermetallic compound thin-walled special-shaped component with gradient properties. Background Art

[0002] In the aerospace field, with the improvement of key index requirements such as the flight speed, flight distance, and flight load of new-generation aircraft, the service conditions of key components such as aircraft structural components, hot-end components, and engines are more severe, and traditional materials are difficult to meet the use requirements. Intermetallic compounds, due to their high strength, low specific gravity, high thermal conductivity, and good oxidation and corrosion resistance at high temperatures, have become potential high-temperature materials to replace nickel-based superalloys.

[0003] At present, for the manufacturing of intermetallic compound thin-walled components, the conventional idea is to first prepare large-sized intermetallic compound slabs and then obtain the final parts through plastic forming. However, due to the intrinsic brittleness of intermetallic compounds, both the slab preparation process and the part forming process are extremely difficult. In view of the manufacturing difficulties of intermetallic compound thin-walled components, invention patents CN107081345A and CN110142332A propose a method of using Ni and Al foil materials to react and synthesize billets, and then preparing the final pipe fittings through plastic forming. The above technical solutions avoid the preparation difficulties of intermetallic compound slabs to a certain extent and make the forming of intermetallic compound thin-walled components possible.

[0004] However, with the complexity of aircraft structures, the load-bearing conditions of key aircraft components have also become more complex. Taking a scramjet engine as an example, in the combustion chamber of this engine, the gas combustion temperature exceeds 2000°C, and there is a strong thermal shock on the combustion chamber wall; at the same time, on the other side of the combustion chamber wall, it is necessary to withstand the cooling effect of liquid hydrogen used as fuel, and the temperature of liquid hydrogen is usually lower than -200°C. In this way, one side of the combustion chamber wall in contact with the combustion gas has to bear extremely high temperatures, and the side in contact with liquid hydrogen has to bear extremely low temperatures. Although intermetallic compounds have excellent high-temperature service performance, their room-temperature plasticity is poor and their fracture toughness is low, making it difficult to meet complex service conditions. At present, domestic and foreign researchers have adopted methods such as microstructural control, alloying, and composite material preparation to improve the mechanical properties of intermetallic compounds. The invention application with publication number CN103057203A proposes a method for preparing a NiAl slab, which is to perform two hot pressing composites on the alternating laminations of Ni foil and Al foil, and finally obtain a laminated NiAl alloy sheet, and use the laminated microstructure to improve the plasticity and toughness of the NiAl alloy. However, the improvement of material properties obtained by this method is limited, and it is still difficult to meet its use requirements.

[0005] The best way to solve this problem is to use functionally graded materials, which are customized according to the different performance requirements of different regions. Taking the temperature characteristics as an example, metal materials can be used in the low-temperature region and intermetallic compounds can be used in the high-temperature region. At present, the preparation methods for functionally graded materials include chemical vapor deposition, physical evaporation, plasma spraying, particle gradient arrangement, self-propagating high-temperature synthesis, etc. However, these methods have low preparation efficiency and are difficult to fabricate large-sized parts or blanks.

[0006] To solve the problems of difficult manufacturing of thin-walled and special-shaped intermetallic compound components and the difficulty of conventional homogeneous materials in meeting severe and complex service conditions, a new method for manufacturing thin-walled and special-shaped intermetallic compound components with gradient performance needs to be developed. Summary of the Invention

[0007] To solve the problems of difficult manufacturing of thin-walled components of intermetallic compounds such as TiAl and NiAl and the difficulty of conventional homogeneous materials in meeting severe and complex service conditions, the present invention proposes a method for manufacturing thin-walled and special-shaped intermetallic compound components with gradient performance.

[0008] Technical solution of the present invention:

[0009] A method for manufacturing a thin-walled and special-shaped intermetallic compound component with gradient performance, the steps are as follows:

[0010] Step 1. Design of the gradient performance of the component: According to the service environment and load characteristics of the component, design the mechanical property indexes of different parts of the component; for example, in the stress concentration part, a high toughness index is preferably selected, and in the part subjected to thermal shock, a high temperature strength index is preferably selected, etc.

[0011] Step 2. Determination of the material distribution of the component: According to the gradient performance of the designed component, determine the material distribution of the component. For example, in the high-temperature and high-strength region, select intermetallic compound material A with a higher ultimate service temperature x B y ; in the region with high toughness requirements, select a more ductile intermetallic compound composite material with high melting point metal wires as reinforcing fibers and intermetallic compound A x B y as the matrix.

[0012] Step 3. Determination of the material ratio of the component: According to the material distribution determined in Step 2, determine the material ratio of different regions; for the intermetallic compound A x B y region, the volume ratio of the A and B element materials is (x × M A ) / ρ A : (y × M B ) / ρ B , where x and y are the atomic numbers of the elements A and B that make up the target intermetallic compound respectively, and M A, M B are the molar masses of elements A and B respectively, and ρ A , ρ B are the densities of elements A and B respectively; for an intermetallic compound composite with a high melting point metal wire as the reinforcing fiber, assuming A is the high melting point metal, the volume ratio of the material is greater than (x × M A ) / ρ A : (y × M B ) / ρ B . For the case where B is the ductile reinforcing material, the volume ratio of the material is less than (x × M A ) / ρ A : (y × M B ) / ρ B . In the intermetallic compound composite, a part of the high melting point metal wire with a relatively higher ratio reacts with the low melting point metal to form an intermetallic compound A x B y , which becomes the matrix of the composite material, and a part still exists in the form of a wire of the metal element, becoming the reinforcing fiber of the composite material.

[0013] Step Four: Design of the metal wire weaving scheme: Use a high melting point metal wire as the wire material. According to the volume ratio of the material determined in Step Three, design the wire diameter, gap, weaving method, weaving path, etc. of the metal wire at different positions, control the different space volumes occupied by the high melting point metal wire at different positions, and the different void volumes at different positions correspond to different volume ratios of the subsequent low melting point metal cast in. Finally, different volume ratios of materials at different positions are achieved. The metal wire weaving methods include plain weave, twill weave, satin weave, basket weave, shuttle weave, pseudo-shuttle weave, etc. The wire diameter range of the metal wire is 0.01 - 1 mm.

[0014] Step Five: Metal wire weaving: According to the metal wire weaving method designed in Step Four, prepare a metal woven preform. Each part of the preform has different wire diameters, gaps, weaving methods, etc. of the metal wire, which can control the volume ratio of the material at different positions, so as to achieve different material tissue properties at different positions finally.

[0015] Step Six: Die casting of the low melting point metal: Place the core mold and the metal woven preform in the die casting mold, fix them completely, then close the mold and heat the mold to at least 50 °C above the melting point of the low melting point metal. Then pour the liquid low melting point metal into the mold, and keep the liquid pressure greater than 0.5 MPa, and the pressure holding time is not less than 5 min until the liquid metal fully fills the weaving voids of the metal woven preform. Then slowly cool the mold and the blank to room temperature, and take out the blank.

[0016] Step 7. Hot pressing and sintering: Put the die-cast blank into a hot isostatic pressing furnace and heat and pressurize it. First, heat the blank to 5 - 100 °C below the melting point of the low-melting-point element, and keep the ambient pressure not lower than 10 MPa until the low-melting-point metal element completely reacts. Subsequently, heat it to 100 - 500 °C below the melting point of the high-melting-point element, and keep the ambient pressure not lower than 10 MPa until the target microstructure is formed.

[0017] Step 8. Post-treatment of the blank: Cut and grind and polish the blank after hot pressing and sintering.

[0018] Advantages of the present invention:

[0019] (1) For the manufacturing method of an intermetallic compound thin-walled special-shaped component with gradient properties of the present invention, the combination of three-dimensional weaving and die-casting processes can directly prepare components with gradient properties, meeting complex service conditions.

[0020] (2) For the manufacturing method of an intermetallic compound thin-walled special-shaped component with gradient properties of the present invention, the combination of three-dimensional weaving and die-casting processes directly obtains the final component shape, avoiding the forming problems of brittle intermetallic compounds and gradient materials. The process is simple and the part quality is reliable.

[0021] (3) For the manufacturing method of an intermetallic compound thin-walled special-shaped component with gradient properties of the present invention, using a metal mesh as the matrix material, the grain size and distribution form of the microstructure of the final reaction-synthesized sheet material can be effectively controlled by adjusting parameters such as the wire diameter of the metal mesh, the gap between the metal mesh holes, and the mesh pattern type, thereby effectively realizing the regulation of the gradient properties of the material.

[0022] (4) For the manufacturing method of an intermetallic compound thin-walled special-shaped component with gradient properties of the present invention, an intermetallic compound reinforced with metal fibers can be prepared. Adding a ductile material to a brittle matrix can effectively improve its fracture toughness while maintaining its high-temperature strength.

[0023] (5) For the manufacturing method of an intermetallic compound thin-walled special-shaped component with gradient properties of the present invention, the diffusion reaction principle is used for reaction synthesis, which can make coarse grains and fine grains alternately distributed in three-dimensional space. The coarse grains of the material ensure the strength of the material, and the fine grains enhance the toughness of the material. The alternating existence of the two types of crystals ensures the high-temperature strength and toughness of the material. Description of the drawings

[0024] Figure 1 It is a process route diagram of a manufacturing method of an intermetallic compound thin-walled special-shaped component with gradient properties.

[0025] Figure 2 It is a schematic diagram of metal wire weaving.

[0026] Figure 3 Schematic diagram of a woven preform with in-plane gradient performance. Among them, (a) is the schematic diagram of the overall structure, (b) is the high-density metal wire layer of the thick-direction gradient metal woven preform, (c) is the medium-density metal wire layer of the thick-direction gradient metal woven preform, and (d) is the low-density metal wire layer of the thick-direction gradient metal woven preform.

[0027] Figure 4 Schematic diagram of a thick-direction gradient performance woven preform.

[0028] Figure 5 Schematic diagram of a multi-wire diameter woven preform.

[0029] Figure 6 Schematic diagram of a multi-material woven preform.

[0030] Figure 7 Schematic diagram of die casting of a metal woven preform.

[0031] Figure 8 Schematic diagram of vacuum die casting of a metal woven preform.

[0032] Figure 9 Schematic diagram of hot pressing and sintering of a metal woven preform.

[0033] In the figure: 1 - high melting point metal wire, 2 - core mold, 3 - in-plane gradient metal woven preform, 4 - thick-direction gradient metal woven preform, 5 - high-density metal wire layer of the thick-direction gradient metal woven preform, 6 - medium-density metal wire layer of the thick-direction gradient metal woven preform, 7 - low-density metal wire layer of the thick-direction gradient metal woven preform, 8 - multi-wire diameter woven preform, 9 - multi-material woven preform, 10 - upper die for die casting, 11 - riser, 12 - lower die, 13 - gate, 14 - upper die for vacuum die casting, 15 - vacuum pump, 16 - vacuum pumping port, 17 - lower die for vacuum die casting, 18 - vacuum die casting gate, 19 - hot isostatic pressing furnace, 20 - component after die casting, 22 - upper die for gas expansion, 23 - pressure application port, 24 - sealing punch, 25 - lower die for gas expansion, 26 - heating plate, 27 - heat insulation plate, 28 - water cooling plate, 29 - preform after die casting. Specific implementation mode

[0034] Combined with the attached drawings and technical solutions, the specific implementation mode of the present invention is further described.

[0035] Example 1: Combined with Figure 1 、 2 、7, 9, a manufacturing method for a thin-walled special-shaped component of an intermetallic compound with gradient performance is as follows:

[0036] Step 1. Component gradient performance design: According to the service environment of the component and the characteristics of the loads it bears, design the mechanical property indexes of different parts of the component; in this embodiment, the final part is an air intake duct with a special-shaped thin-walled structure, which is subjected to a large thermal shock inside, and the high-temperature strength index is preferably selected. It is connected to other components outside, and stress concentration is likely to occur, so the high-toughness index is preferably selected.

[0037] Step 2. Determination of component material distribution: According to the gradient performance of the designed component, determine the material distribution of the component. Select the intermetallic compound material NiAl with a higher ultimate service temperature in the internal high-temperature and high-strength region, and select the intermetallic compound composite material with better toughness using the high-melting-point metal wire Ni as the reinforcing fiber and the intermetallic compound NiAl as the matrix in the external high-toughness demand region.

[0038] Step 3. Determination of component material ratio: According to the material distribution determined in Step 2, determine the material ratios of different regions; for the NiAl intermetallic compound region, the volume ratio of the Ni and Al element materials is (1×M Ni ) / ρ Ni :(1×M Al ) / ρ Al , that is, approximately equal to 6.6:10.0. M Ni , M Al are the molar masses of elements Ni and Al respectively, and ρ Ni , ρ Al are the densities of elements Ni and Al respectively; for the intermetallic compound composite material using the high-melting-point metal wire Ni as the reinforcing fiber, the material volume ratio is greater than 6.6:10.0. In the intermetallic compound composite material, a relatively higher proportion of the high-melting-point metal wire Ni reacts with the low-melting-point metal Al to form the intermetallic compound NiAl, becoming the matrix of the composite material, and a part still exists in the form of the wire of the metal element Ni, becoming the reinforcing fiber of the composite material.

[0039] Step 4. Design of metal wire braiding scheme: Use the high-melting-point metal wire Ni as the wire material, and design the wire diameter, gap, braiding method, braiding path, etc. of the metal wire with a gradient change from inside to outside according to the volume ratio of Ni and Al materials determined in Step 3, and control the space volume occupied by the high-melting-point metal wire Ni to increase gradually from inside to outside, while the volume ratio of the subsequent low-melting-point metal Al die-cast into the corresponding void volume decreases gradually from inside to outside, finally realizing the gradient change of the material volume ratio in the thickness direction. In this embodiment, by using Ni metal wires that become thicker layer by layer, decreasing braiding gaps layer by layer, and a braiding method with an increasing areal density from inside to outside, the gradient increase of the Ni ratio and the gradient decrease of the Al ratio in the thickness direction are achieved.

[0040] Step 5. Metal wire braiding: Prepare a Ni metal braided preform according to the metal wire braiding method designed in Step 4.

[0041] Step 6. Die casting of low-melting-point metal: Place the core mold and Ni metal braided preform in the die-casting mold, fix them completely, then close the mold and heat the mold to at least 710 °C. Subsequently, pour the liquid low-melting-point metal Al into the mold, and maintain the liquid pressure greater than 0.5 MPa for at least 5 min until the liquid metal Al is fully filled into the braided voids of the metal braided preform. Then, slowly cool the mold and the blank to room temperature and take out the blank.

[0042] Step 7. Hot pressing and sintering: Place the die-cast blank in a hot isostatic pressing furnace and heat and pressurize it. First, heat the blank to 600 °C and maintain the ambient pressure not less than 10 MPa until the low-melting-point metal element Al completely reacts. Then, heat it to 1200 °C below the melting point of the high-melting-point element Ni and maintain the ambient pressure not less than 10 MPa until the target microstructure NiAl is formed.

[0043] Step 8. Post-treatment of the blank: Cut and grind and polish the hot-pressed and sintered blank.

[0044] Advantages of this embodiment: This process combines three-dimensional braiding and die-casting processes, and can directly prepare intermetallic compound thin-walled components with gradient properties, avoiding the forming problems of brittle intermetallic compounds and gradient materials. The process is simple and the part quality is reliable. And by adjusting the parameters of each part of the braided body, the customization and regulation of material properties can be easily achieved. At the same time, the intermetallic compound obtained by the process has coarse-grained and fine-grained regions alternately distributed in three-dimensional space, and the fracture toughness of the material is significantly improved. Material structure analysis shows that there are obvious differences in the inner and outer layer microstructures. The inner layer is composed entirely of the intermetallic compound NiAl, and Ni single-wire materials remain in the matrix intermetallic compound NiAl in the outer layer. Mechanical property analysis shows that for the gradient material obtained by this process, under the same thermal shock inside, the toughness is significantly improved.

[0045] Example 2: Combined Figure 3 Description: In Steps 2 to 5, the in-plane gradient property change of the component is realized by changing the wire density of the metal wires at local positions. The remaining steps are the same as those in the first specific embodiment.

[0046] Advantages of this embodiment: Changing the wire density of the metal wires at local positions can effectively change the material ratio at this position and realize the customization of in-plane properties.

[0047] Example 3: Combined Figure 4 Description: In Steps 2 to 5, the gradient change of the component's thickness direction properties is realized by changing the wire density of each layer of the metal braided body.

[0048] Advantages of this embodiment: By changing the wire density of each layer of the metal braid, the gradient change of the component's through-thickness performance can be achieved, obtaining a through-thickness composite material, thereby improving the overall mechanical properties of the component. While having good high-temperature strength, it also has good room-temperature toughness.

[0049] Example 4: As described in combination with Figure 5 In steps 2 to 5, during the continuous braiding process, metal wire braided preforms are prepared using metal wires with different wire diameters. The remaining steps are the same as those in Embodiment 1.

[0050] Advantages of this embodiment: Using metal wires with different wire diameters can obtain a spatially distributed network of reinforcing fibers throughout the component, enabling the component to simultaneously achieve good strength and toughness.

[0051] Example 5: As described in combination with Figure 6 In the design and braiding process of the braid, metal wires of different materials are used to prepare metal wire braided preforms simultaneously, such as carbon fibers, glass fibers, etc. The remaining steps are the same as those in Embodiment 1.

[0052] Advantages of this embodiment: Adding other material fibers such as carbon fibers to the braid can fiber-reinforce the final material, effectively improving the strength and toughness of the material.

[0053] Example 6: As described in combination with Figure 6 In step 6, a vacuum die-casting process is used to prepare the component. The remaining steps are the same as those in Specific Embodiment 1.

[0054] Advantages of this example: The vacuum die-casting process can effectively remove the residual air in the mold, avoid the generation of pores in the component, improve the density of the component, and at the same time reduce the oxidation of the metal wire mesh during the die-casting process, increase the reliability of the component, and ensure the mechanical properties of the final component.

[0055] Example 7: For parts with complex surface features that are difficult to braid directly, first simplify the shape of the component to make it a braidable body for braiding, and perform hot gas inflation after die-casting to form local surface features. The hot gas inflation temperature is from room temperature to 50°C below the melting point of the lower melting point metal in the material system. The remaining steps are the same as those in Embodiment 1.

[0056] Advantages of this example: Adding the hot gas inflation step in the process can effectively reduce the braiding difficulty of special-shaped components and simplify the braiding process.

Claims

1. A method for manufacturing a thin-walled special-shaped intermetallic compound component with gradient performance, characterized in that: Here are the steps: Step 1: Component gradient performance design: Design the mechanical performance indicators of different parts of the component according to the component's service environment and load characteristics; Step 2: Determine the material distribution of the component: Determine the material distribution of the component based on the gradient performance of the designed component, and select intermetallic compound material A with a higher limit service temperature in the high temperature and high strength area. x B y In areas requiring high toughness, high melting point metal wires are used as reinforcing fibers, and intermetallic compounds A x B y Intermetallic compound composites with better toughness for the matrix; Step 3: Determine the material ratio of the component: According to the material distribution determined in step 2, determine the material ratio of different areas; Step 4: Design of metal wire weaving scheme: Use high-melting-point metal wire as wire material, design the wire diameter, gap, weaving method, and weaving path of metal wires at different positions according to the material volume ratio determined in step 3, control the different spatial volumes occupied by high-melting-point metal wires at different positions, and the different void volumes at different positions correspond to the different volume proportions of low-melting-point metals that are subsequently die-cast, so as to achieve different material volume ratios at different positions; Step 5, metal wire weaving: according to the metal wire weaving method designed in step 4, a metal braided preform is prepared, and different parts of the metal braided preform have different metal wire diameters, gaps, and weaving methods, and the material volume ratio at different positions is controlled, so as to achieve different material organization properties at different positions; Step 6: Die-casting of low-melting-point metal: Place the core mold and the metal braided preform in the die-casting mold, fix them completely, then close the mold and heat the die-casting mold to at least 50°C above the melting point of the low-melting-point metal, then pour the liquid low-melting-point metal into the die-casting mold, and keep the liquid pressure greater than 0.5MPa for a holding time of not less than 5min until the liquid metal is fully filled into the braiding gaps of the metal braided preform, then slowly cool the die-casting mold and the blank to room temperature, and take out the blank; Step 7: Hot pressing and sintering: Place the die-cast blank into a hot isostatic pressing furnace and heat and pressurize it; Step 8: Post-processing of the blank: cutting and grinding and polishing the blank after hot pressing and sintering.

2. The method for manufacturing a thin-walled special-shaped intermetallic compound component with gradient performance according to claim 1, characterized in that: The specific implementation of step three is as follows: Intermetallic compound A x B y The volume ratio of A and B elements is (x×M A ) / ρ A :(y×M B ) / ρ B , where x and y are the atomic numbers of elements A and B respectively, and M A 、M B are the molar masses of elements A and B, respectively, A , B are the densities of elements A and B respectively; for the intermetallic compound composite material with high melting point metal wire as reinforcing fiber, assuming that element A is a high melting point metal, the volume ratio of the intermetallic compound composite material is greater than (x×M A ) / ρ A :(y×M B ) / ρ B For the toughness enhancing material with element B, the volume ratio of the intermetallic compound composite material is less than (x×M A ) / ρ A :(y×M B ) / ρ B In the intermetallic compound composite material, a portion of the high-melting-point metal wire with a relatively higher proportion reacts with the low-melting-point metal to form an intermetallic compound A x B y , becoming the matrix of the composite material, and the other part still exists in the form of metal wire, becoming the reinforcing fiber of the composite material.

3. The method for manufacturing a thin-walled special-shaped intermetallic compound component with gradient performance according to claim 1, characterized in that: Metal wire weaving methods include plain weave, twill, satin weave, basket weave, woven, and imitation woven.

4. The method for manufacturing a thin-walled special-shaped intermetallic compound component with gradient performance according to claim 1, characterized in that: The wire diameter ranges from 0.01 to 1 mm.

5. The method for manufacturing a thin-walled special-shaped intermetallic compound component with gradient performance according to claim 1, characterized in that: The specific implementation of step seven is as follows: first, heat the blank to 5-100°C below the melting point of the low-melting-point element, maintain the ambient pressure not less than 10MPa, until the low-melting-point metal element is completely reacted, and then heat to 100-500°C below the melting point of the high-melting-point element, and maintain the ambient pressure not less than 10MPa, until the target microstructure is generated.

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