Intermetallic compound thin-wall special-shaped component manufacturing method based on wire mesh weaving and pressure infiltration

Abstract

The invention belongs to the technical field of preparation of intermetallic compound thin-wall special-shaped parts, and discloses a manufacturing method of an intermetallic compound thin-wall special-shaped part based on wire mesh weaving and pressure infiltration. According to the manufacturing method, the forming process of the brittle intermetallic compound is avoided, and the forming difficulty is effectively reduced. Moreover, the weaving of the metal wire mesh is combined with pressure infiltration, so that the thin-wall integral prefabricated blank which is complex in structure, uniform in wall thickness and similar to a final part in shape is prepared, the deformation in the subsequent forming process can be reduced, and the problem of final cracking caused by excessive reduction of the wall thickness due to local bulging in the forming process is avoided; and the problem that the blank is wrinkled due to local deformation in the mold closing process or is undercut at the mold splitting position is also avoided.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of intermetallic compound thin-walled special-shaped parts, and relates to a method for manufacturing intermetallic compound thin-walled special-shaped components based on metal wire mesh weaving and pressure infiltration. Background Art

[0002] The new generation of aerospace vehicles are developing rapidly in the direction of high Mach number, high load, ultra-long flight time and ultra-long range, and the demand for lightweight, high-temperature resistant thin-walled components is increasing. Typical demands include the leading edge of the aircraft, the engine air inlet, etc. Faced with higher service temperatures and more stringent working conditions, the existing titanium alloys can no longer meet the requirements. Nickel-based high-temperature alloys can serve under very high temperature conditions, but their high density can easily cause the problem of overweight structure. Therefore, new lightweight and high-temperature resistant structural materials such as TiAl, NiAl and other intermetallic compounds are receiving more and more attention. Intermetallic compounds such as TiAl and NiAl have the advantages of high service temperature, low density, high specific strength, high specific stiffness and excellent oxidation resistance, and have broad application prospects in the aerospace field.

[0003] For TiAl and NiAl thin-walled special-shaped components, the commonly used manufacturing method is to first prepare a thin-walled slab with a certain size, and then obtain a thin-walled special-shaped component by superplastic forming at a temperature above 800°C. However, due to the intrinsic brittleness of intermetallic compounds, the preparation of thin-walled slabs and the forming and manufacturing of components are extremely difficult. This is because: on the one hand, when using rolling and other processes to prepare thin-walled slabs, due to the large number of related constraints and complex thermal strain states, cracking is easy to occur during the rolling process of thin-walled slabs, and it is difficult to obtain large-sized, high-quality thin-walled slabs; on the other hand, the superplastic forming process has very high requirements on the original structure of the material, and microscopic holes are prone to appear after the material undergoes large deformation, resulting in weakened organizational properties. In addition, large deformation will also cause serious thinning and uneven wall thickness at various locations on the component, making it difficult to meet complex load-bearing requirements.

[0004] To solve the above problems, invention patents CN107081345A and CN110142332A proposed a method of preparing simple thin-walled blanks by reaction synthesis of Ni and Al foils, and then manufacturing the final complex pipe fittings by plastic forming. However, in this process, the thin-walled blank still needs to undergo complex plastic deformation, so it is impossible to avoid the problem of weakened material performance and serious uneven wall thickness after deformation. Invention patents CN112091049A, CN113798394A, and CN111168407A proposed a process method of preparing thin-walled parts with a shape and size similar to the final component by continuous winding of metal foil strips, and then obtaining the final component by shaping at high temperature. This method greatly reduces the deformation of the material at high temperature, which is conducive to solving the problems of weakened performance and thinning of wall thickness. However, since there will be a certain small gap between adjacent metal foil strips during the winding process, these small gaps are difficult to completely eliminate in the subsequent hot pressing and reaction synthesis stages, so they affect the mechanical properties of the final component to a certain extent, and it is difficult to meet its use requirements.

[0005] In order to solve the problems of intrinsic brittleness, poor fracture toughness, difficulty in preparing thin-walled billets, extreme difficulty in deforming materials at room temperature and warm conditions, weakened performance and uneven wall thickness during component forming, etc., it is necessary to develop a new method for manufacturing intermetallic compound thin-walled special-shaped components. Summary of the invention

[0006] In order to solve the problems of intrinsic brittleness, poor fracture toughness, difficulty in preparing thin-walled blanks, extreme difficulty in deforming materials at room temperature and warm state, weakened performance and uneven wall thickness during component forming process of intermetallic compound materials such as TiAl and NiAl, the present invention proposes a method for manufacturing intermetallic compound thin-walled special-shaped components based on metal wire mesh weaving and pressure infiltration.

[0007] The technical solution of the present invention:

[0008] A method for manufacturing intermetallic compound thin-walled special-shaped components based on metal wire mesh weaving and pressure infiltration, the steps are as follows:

[0009] Step 1: Determine the component material system; according to the target intermetallic compound A x B y , select the metal element B with a higher melting point as the matrix, and use the metal element B to weave the wire mesh; the volume ratio of A and B materials is: (x×M A ) / ρ A :(y×M B ) / ρ B , where x and y are the number of atoms of metal elements A and B constituting the target intermetallic compound, respectively, and M A 、M B are the molar masses of metal elements A and B, respectively,A , B are the densities of metal elements A and B respectively, and the volume fraction of metal element A is ((x×M A ) / ρ A ) / ((x×M A ) / ρ A +(y×M B ) / ρ B ), the volume fraction of metal element B is ((y×M B ) / ρ B ) / ((x×M A ) / ρ A +(y×M B ) / ρ B );

[0010] Step 2, core mold preparation; design the preform according to the shape and wall thickness of the target part; the equivalent diameter of the axial section of the preform is close to that of the target part, and the equivalent diameter of the section changes continuously to ensure that the shape of the preform is close to that of the target part; prepare the core mold according to the inner surface contour of the preform;

[0011] Step 3: Design the metal wire weaving path; according to the volume ratio of the metal element determined in step 1, determine the wire diameter and wire spacing; wherein the wire diameter ranges from 0.01 to 0.5 mm, and the mesh spacing ranges from 0.01 to 0.5 mm;

[0012] Step 4, wire weaving: using the core mold designed in step 2, designing the wire weaving path according to step 3, and continuously weaving the wire on the surface of the core mold to obtain a wire weaving preform;

[0013] Step 5, low-melting-point metal die-casting; install the wire braided preform with the core mold in the infiltration mold, heat the infiltration mold to at least 50°C above the melting point of the low-melting-point metal element, and then pour the low-melting-point liquid metal from the mold gate into the infiltration mold, provide a casting pressure of not less than 1MPa, and maintain the pressure for not less than 5 minutes until the low-melting-point liquid metal fully fills the mesh gap of the wire braided preform, then cool the infiltration mold and the infiltrated blank to room temperature, take out the blank, and remove the core mold;

[0014] Step 6: Plastic forming of the preform; placing the infiltrated blank in a forming mold, using a hot air expansion process to form the micro features of the component, the forming pressure is 70MPa, the pressure is maintained for 5-8min, and the forming temperature range is from room temperature to below the melting point of the low-melting-point metal element to obtain the formed component;

[0015] Step 7: Reaction to synthesize intermetallic compounds; placing the formed component in a hot isostatic pressing furnace, and performing two-stage heating and pressurization, the heating temperature of the first stage is 10-50°C below the melting point of the low-melting-point metal element, the applied pressure is not less than 5MPa, and the loading time is not less than the time required for the low-melting-point metal element to fully react; after the low-melting-point metal element is completely reacted, entering the second stage of heating and pressurization, the heating temperature is below the melting point of the high-melting-point metal element and above the melting point of the low-melting-point metal element, the applied pressure is not less than 5MPa, and the loading is maintained until the metal elements A and B fully react to synthesize the target intermetallic compound A x B y ;

[0016] Step 8: Processing of components after forming: taking out the final component after reaction synthesis, and cutting and grinding and polishing it.

[0017] The beneficial effects of the present invention are:

[0018] (1) The present invention provides a method for manufacturing intermetallic compound thin-walled special-shaped components based on metal mesh weaving and pressure infiltration, which avoids the forming process of brittle intermetallic compounds and effectively reduces the difficulty of forming. In addition, the metal mesh weaving is combined with pressure infiltration to prepare a thin-walled integral prefabricated blank with a complex structure, uniform wall thickness, and a shape close to the final part, which can reduce the deformation amount in the subsequent forming process, avoid the problem of excessive thinning of the wall thickness and final cracking due to local bulging during the forming process, and avoid the problem of wrinkling of the blank due to local deformation during the mold closing process or undercutting at the parting point.

[0019] (2) The present invention provides a method for manufacturing thin-walled special-shaped intermetallic compounds based on metal wire mesh weaving and pressure infiltration, which uses metal wire mesh as the matrix material. The microstructure of the material after the final reaction synthesis, such as grain size and distribution form, can be controlled by adjusting parameters such as the wire diameter, wire mesh gap, and mesh type of the metal wire mesh, thereby achieving accurate regulation of material properties.

[0020] (3) The present invention provides a method for manufacturing intermetallic compound thin-walled special-shaped components based on metal wire mesh weaving and pressure infiltration, using metal wire mesh as raw material for reaction synthesis, and finally synthesizing a metal tube with alternating coarse and fine grain regions in three-dimensional space. The existence of the coarse grain region ensures the high strength of the material, while the fine grain region enhances the toughness of the material. At the same time, the alternating appearance of the coarse and fine grain regions also effectively inhibits the expansion of cracks, so that the fracture toughness of the material is significantly enhanced.

[0021] (4) The present invention provides a method for manufacturing intermetallic compound thin-walled special-shaped components based on metal wire mesh weaving and pressure infiltration. The pressure infiltration process utilizes the fluidity of liquid metal and also effectively solves the problem of material performance degradation caused by the gap between foils during continuous winding. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention provides a process roadmap for the manufacturing method of intermetallic compound thin-walled special-shaped components with three-dimensional network structure based on pressure infiltration.

[0023] Figure 2 Schematic diagram of the structure of the metal wire braided preform.

[0024] Figure 3 Schematic diagram of infiltration of wire braided preform.

[0025] Figure 4 Schematic diagram of the preform after infiltration.

[0026] Figure 5 Schematic diagram of thermal expansion of preform after infiltration.

[0027] Figure 6 Schematic diagram of high temperature and high pressure reaction synthesis after hot gas expansion.

[0028] Figure 7 Schematic diagram of vacuum die casting of metal wire braided preform.

[0029] In the figure: 1-high melting point metal wire, 2-core mold, 3-metal wire braided preform, 4-infiltration upper mold, 5-riser, 6-lower mold, 7-gate, 8-low melting point filling matrix, 9-infiltration preform, 10-hot air expansion upper mold, 11-pressurization port, 12-sealing punch, 13-hot air expansion lower mold, 14-heating plate, 15-insulation plate, 16-water cooling plate, 17-hot isostatic pressing furnace, 18-formed component, 19-vacuum infiltration upper mold, 20-vacuum pump, 21-vacuum exhaust port, 22-vacuum infiltration lower mold, 23-vacuum infiltration gate. DETAILED DESCRIPTION

[0030] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0031] Example 1: Combination Figures 1 to 6 A method for manufacturing thin-walled special-shaped intermetallic compound components based on metal mesh weaving and pressure infiltration is described, and the specific steps are as follows:

[0032] Step 1: Determine the material ratio. According to the target intermetallic compound A x B y, select the element with higher melting point as the metal wire braiding preform, and calculate the volume proportion of the metal wire used. Assuming that element B has higher melting point, its volume proportion is ((y×M B ) / ρ B ) / ((x×M A ) / ρ A +(y×M B ) / ρ B ). Taking NiAl, TiAl, and FeAl alloys as an example, the volume proportion of Ni element should be 39.8%, the volume ratio of Ni to Al should be 1:1.51, the volume proportion of Ti element should be 51.2%, the volume ratio of Ti to Al should be 1.05:1, the volume proportion of Fe element should be 41.6%, and the volume ratio of Fe to Al should be 1:1.40.

[0033] Step 2: Mandrel mold preparation. Design the shape of the preform according to the final shape and wall thickness of the target part, ensure that the equivalent diameter of the axial section of the preform is close to that of the final part, and that the equivalent diameter of the section changes continuously, and the shape of the preform is close to that of the final target part. Prepare the mandrel mold according to the inner surface contour of the preform.

[0034] Step 3: Design of wire weaving scheme. Calculate the required volume ratio according to step 1, and determine the wire diameter and wire spacing. The wire diameter ranges from 0.01-0.5mm, and the mesh gap ranges from 0.01-0.5mm. Taking NiAl, TiAl, and FeAl alloys as examples, the Ni mesh selects a wire diameter of 0.15mm and a mesh gap of 0.5mm, the Ti mesh selects a wire diameter of 0.2mm and a mesh gap of 0.5mm, and the Fe mesh selects a wire diameter of 0.15mm and a mesh gap of 0.5mm.

[0035] Step 4: Metal wire weaving: Using the core mold designed in step 2 and the metal wire weaving method designed in step 3, the metal wires are continuously weaved on the surface of the core mold to obtain a metal wire weaving preform.

[0036] Step 5: Die-casting of low-melting-point metals. Install the metal braided preform with the core mold in the infiltration mold, heat the mold to at least 50°C above the melting point of the low-melting-point elemental metal, and then pour the low-melting-point liquid metal into the mold from the mold gate, provide a casting pressure of not less than 1MPa, and maintain the pressure for not less than 5 minutes until the liquid metal fully fills the mesh gaps of the braided preform, then cool the mold and the cast preform to room temperature, take out the preform, and remove its core mold. For NiAl, TiAl, and FeAl alloys as examples, the mold is heated to above 660°C, and Al liquid is poured into the mold.

[0037] Step 6: Plastic forming of the preform. The preform is placed in a forming mold and the hot air expansion process is used to form the tiny features of the component. The forming pressure is 70MPa, and the pressure is maintained for 5-8 minutes. The forming temperature range includes room temperature to below the melting point of low-melting-point metals. For example, for NiAl, TiAl, and FeAl alloys, the forming temperature is lower than 660°C.

[0038] Step 7: Reaction to synthesize intermetallic compounds. Place the formed components in a hot isostatic pressing furnace and perform two-stage heating and pressurization. The heating temperature in the first stage is 10-50°C below the melting point of the low-melting-point metal, the applied pressure is not less than 5MPa, and the loading time is not less than the time required for the low-melting-point metal to fully react. After the low-melting-point metal has completely reacted, enter the second stage of heating and pressurization. The heating temperature is below the melting point of the high-melting-point metal and more than 100°C higher than the melting point of the low-melting-point metal. The applied pressure is not less than 5MPa, and the loading is maintained until the elements are fully reacted to form the target intermetallic compound A. x B y Taking NiAl, TiAl and FeAl alloys as examples, the heating temperature in the first stage is 610-650℃, and the reaction time is 5-6h. In the second stage, the heating temperature of NiAl is 1400-1440℃, the heating temperature of TiAl is 1620-1660℃, and the heating temperature of FeAl is 1490-1530℃, and the reaction time is 5-6h.

[0039] Step 8: Part post-processing: Take out the final parts and perform necessary cutting and grinding and polishing.

[0040] Beneficial effects of this embodiment: This process avoids plastic forming of metal compound, reduces the difficulty of component forming, and combines pressure wire weaving with pressure infiltration to obtain thin-walled integral prefabricated material with a shape close to the final part, reducing the deformation in the subsequent forming process and avoiding the formation of forming defects to a certain extent. In addition, the final component of this process has coarse and fine grain areas distributed alternately in the three-dimensional space, which effectively inhibits the expansion of cracks and significantly enhances the fracture toughness of the material; and the use of metal mesh as the matrix material can effectively control the grain size and distribution form of the microstructure of the sheet after the final reaction synthesis by adjusting parameters such as the metal mesh wire diameter, metal mesh gap, and wire mesh weaving type, thereby effectively realizing the regulation of material properties.

[0041] Example 2: For components with relatively simple shapes that do not require plastic forming, in step five, after the low-melting-point liquid metal is poured, the mold and liquid metal temperatures are maintained at more than 100°C higher than the melting point of the low-melting-point metal, and the pouring pressure is maintained at 1MPa until the two elements fully react to form the target intermetallic compound. The component is then slowly cooled to room temperature, the mold is opened to remove the component, and necessary cutting, grinding and polishing are performed on the component.

[0042] The beneficial effects of this embodiment are: for components with relatively simple shapes, direct in-situ reaction to synthesize the final parts can effectively shorten the process route, improve efficiency, and reduce production costs, and the in-situ reaction can continuously replenish metal elements to ensure sufficient reaction of the final material.

[0043] Example 3: Combination Figure 7 It is noted that in step 5, a vacuum die-casting process is used to prepare the preform. The remaining steps are the same as those in the first embodiment.

[0044] The beneficial effects of this embodiment are: the use of the vacuum die-casting process can effectively remove residual air in the mold, avoid the formation of pores in the component, and at the same time reduce the oxidation of the metal wire mesh during the die-casting process, thereby improving the density of the component, increasing the reliability of the component, and ensuring the mechanical properties of the final component.

[0045] Example 4: In step 2, a core mold is prepared using materials such as graphite, boron nitride, and aluminum oxide, and the remaining steps are the same as those in specific implementation mode 1.

[0046] The beneficial effects of this embodiment are: materials such as graphite, boron nitride, and aluminum oxide have good chemical stability and lubrication properties. Using these materials to prepare the core mold can avoid contamination of the core mold material to the final component and facilitate demoulding.

Claims

1. A method for manufacturing intermetallic compound thin-walled special-shaped components based on metal mesh weaving and pressure infiltration, characterized in that: Here are the steps: Step 1: Determine the component material system; according to the target intermetallic compound A x B y , select the metal element B with a higher melting point as the matrix, and use the metal element B to weave the wire mesh; the volume ratio of A and B materials is: (x×M A ) / ρ A :(y×M B ) / ρ B , where x and y are the number of atoms of metal elements A and B constituting the target intermetallic compound, respectively, and M A 、M B are the molar masses of metal elements A and B, respectively, A , B are the densities of metal elements A and B respectively; Step 2, core mold preparation; design the preform according to the shape and wall thickness of the target part; the equivalent diameter of the axial section of the preform is close to that of the target part, and the equivalent diameter of the section changes continuously to ensure that the shape of the preform is close to that of the target part; prepare the core mold according to the inner surface contour of the preform; Step 3: Designing a metal wire weaving path; determining the metal wire diameter and the metal wire spacing according to the volume ratio of the metal element determined in step 1; Step 4, wire weaving: using the core mold designed in step 2, designing the wire weaving path according to step 3, and continuously weaving the wire on the surface of the core mold to obtain a wire weaving preform; Step 5, low melting point metal die casting; installing the wire braided preform with the core mold in the infiltration mold, pouring the low melting point liquid metal from the mold gate into the infiltration mold, heating and pressurizing until the low melting point liquid metal fully fills the mesh gaps of the wire braided preform, then cooling the infiltration mold and the infiltrated blank to room temperature, taking out the blank, and removing the core mold; Step 6: Plastic forming of the preform: placing the infiltrated blank in a forming mold, using a hot air expansion process to form the micro features of the component, and obtaining the formed component; Step 7, reacting to synthesize an intermetallic compound; The formed components are placed in a hot isostatic pressing furnace for heating and pressurization to fully react and synthesize the target intermetallic compound A. x B y ; Step 8: Processing of components after forming: taking out the final component after reaction synthesis, and cutting and grinding and polishing it.

2. The method for manufacturing intermetallic compound thin-walled special-shaped components according to claim 1, characterized in that: In step 1, the volume fraction of metal element A is ((x×M A ) / ρ A ) / ((x×M A ) / ρ A +(y×M B ) / ρ B ), the volume fraction of metal element B is ((y×M B ) / ρ B ) / ((x×M A ) / ρ A +(y×M B ) / ρ B ).

3. The method for manufacturing intermetallic compound thin-walled special-shaped components according to claim 1, characterized in that: In step three, the wire diameter range is 0.01-0.5 mm, and the mesh gap is 0.01-0.5 mm.

4. The method for manufacturing intermetallic compound thin-walled special-shaped components according to claim 1, characterized in that: In step five, the conditions of heating and pressurizing are: heating the infiltration mold to at least 50°C above the melting point of the low-melting-point metal element, and then pouring the low-melting-point liquid metal into the infiltration mold from the mold gate, providing a casting pressure of not less than 1 MPa, and maintaining the pressure for not less than 5 minutes until the low-melting-point liquid metal fully fills the mesh gaps of the metal wire woven preform.

5. The method for manufacturing intermetallic compound thin-walled special-shaped components according to claim 1, characterized in that: In step six, the forming pressure is 70 MPa, the pressure is maintained for 5-8 minutes, and the forming temperature ranges from room temperature to below the melting point of the low-melting-point metal element.

6. The method for manufacturing intermetallic compound thin-walled special-shaped components according to claim 1, characterized in that: In step 7, heating and pressurizing are divided into two stages. In the first stage, the heating temperature is 10-50°C below the melting point of the low-melting-point metal element, the applied pressure is not less than 5MPa, and the loading time is not less than the time required for the low-melting-point metal element to fully react. After the low-melting-point metal element is completely reacted, the second stage of heating and pressurizing is entered, the heating temperature is below the melting point of the high-melting-point metal element and above the melting point of the low-melting-point metal element, the applied pressure is not less than 5MPa, and the loading is maintained until the metal elements A and B fully react to synthesize the target intermetallic compound A. x B y .

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