Preparation method of intermetallic compound seamless tube with three-dimensional network structure

Abstract

The invention discloses a preparation method of an intermetallic compound seamless tube with a three-dimensional network structure. The metal wire mesh is adopted as a raw material, coarse grain and fine grain areas which are alternately distributed exist in the three-dimensional space of the synthesized metal tube, the coarse grain areas guarantee the high strength of the material, the fine grain areas enhance the toughness of the material, and meanwhile, the coarse grain and fine grain areas which alternately exist also effectively inhibit the expansion of cracks, so that the toughness of the material is improved. And the fracture toughness of the material is obviously enhanced. By adjusting the parameters of the metal wire and controlling the microstructure of the synthesized material, the accurate regulation and control of the material performance are realized. The metal wire mesh is adopted as a reaction matrix of high-melting-point elements, the characteristic that the metal wire mesh can be continuously woven is utilized, pipe blanks with different diameters and unlimited lengths can be prepared, and batch continuous production is achieved. And the hot pressing condition with the temperature higher than that of the low-melting-point material is adopted, and the liquidity of liquid metal is utilized, so that the problem that the material performance is reduced due to foil gaps in the continuous winding process is effectively solved.

Description

Technical Field

[0001] The invention belongs to the technical field of intermetallic compound pipe preparation, and relates to a method for preparing an intermetallic compound seamless pipe with a three-dimensional network structure. Background Art

[0002] The new generation of aerospace vehicles is developing rapidly in the direction of high Mach number, high load, ultra-long flight time and ultra-long range. The demand for lightweight, high-temperature resistant thin-walled pipes is increasing. Typical demands include engine air intakes, fuel pipes, etc. Faced with higher service temperatures and more stringent working conditions, existing titanium alloys can no longer meet the requirements. Although nickel-based high-temperature alloys can serve at higher temperatures, their high density can easily cause overweight structures. Therefore, new lightweight, high-temperature resistant structural materials such as TiAl, NiAl and other intermetallic compounds have gradually become a research hotspot. 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] There are usually two methods for manufacturing thin-walled pipes: one is to use strips for continuous roll bending to obtain the target cross-section, and then weld at the butt joint to obtain the final pipe fittings; the other is to use continuous extrusion to directly obtain pipe fittings. However, for intermetallic compounds, since the material itself is brittle and has extremely poor deformation ability, and both the continuous roll bending deformation process and the extrusion process require high material deformation ability, the forming process is extremely complex and difficult. In addition, the pipe fittings obtained by the roll bending welding process usually have significant differences between the weld structure in the welding area and the matrix structure of the pipe fittings, which also leads to uneven performance of the pipe fittings. In order to solve the problem of preparing intermetallic compound pipe fittings. Invention patent CN110142332A proposes a method for integrating the forming and controllability of NiA1 alloy thin-walled pipe fittings, in which Ni and Al laminated foils are pre-rolled and welded, and then Ni and Al laminated tubes are reacted and synthesized to obtain the final pipe fittings. This method avoids the bending process of brittle NiAl alloys. However, this method also cannot avoid the difference between the weld area structure and the matrix structure, resulting in uneven performance of the pipe fittings. To this end, the invention patent publication number CN112091049A proposes the use of continuous winding of metal foil strips to prepare intermetallic compound thin-walled components. The use of continuous winding of foil strips avoids the appearance of welds. However, since there will be certain tiny gaps between the foil strips during the winding process, these tiny gaps are difficult to completely eliminate in the subsequent hot pressing and reaction synthesis stages, and therefore affect the mechanical properties of the final component to a certain extent.

[0004] In addition, the poor room temperature plasticity, low fracture resistance and high temperature strength of intermetallic compounds have also restricted the widespread application of this material to a certain extent. For this reason, researchers at home and abroad have adopted microstructure regulation, alloying, and preparation of composite materials to improve the mechanical properties of intermetallic compounds. The invention application with publication number CN103057203A proposes a method for preparing NiAl slabs, which is to perform two hot pressing composites on alternating laminated slabs of Ni foil and Al foil to finally obtain a layered NiAl alloy sheet, and the layered microstructure is used to improve the plasticity and toughness of NiAl alloy.

[0005] The preparation of intermetallic compound tubes is one of the most important topics in its practical research. In order to solve the problems of difficulty in preparing intermetallic compound tubes and poor mechanical properties of materials, it is necessary to develop a new method for manufacturing intermetallic compound tubes. Summary of the invention

[0006] In order to solve the problems of difficulty in preparing intermetallic compound pipes and poor mechanical properties of pipe fittings, the present invention proposes a method for preparing an intermetallic compound seamless pipe with a three-dimensional network structure.

[0007] The technical solution of the present invention:

[0008] A method for preparing an intermetallic compound seamless tube having a three-dimensional network structure, comprising the following steps:

[0009] Step 1: Determine the volume fraction of raw materials: According to the target intermetallic compound A x B y The volume of raw materials required for component calculation, 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 the target intermetallic compound constituent elements A and B, respectively, and M A 、M B are the molar masses of elements A and B, respectively, and ρ A , B are the densities of elements A and B respectively;

[0010] Step 2, determining the reaction matrix: select the material with higher melting point among the two materials and weave it into a metal mesh with metal filaments, the wire diameter of the wire mesh is 0.01-0.5mm, and the mesh gap is 0.01-0.5mm; the material with lower melting point adopts metal foil, and the thickness of the foil is 0.01-2mm; assuming that material A is a material with higher melting point and material B is a material with lower melting point, then the volume ratio of the metal mesh to the metal foil is the volume ratio calculated in step 1;

[0011] Step 3: Material pretreatment: Use organic solvent to ultrasonically clean the material surface to remove oil stains;

[0012] Step 4: Preform production: According to the wire diameter, mesh gap and weaving form of the wire mesh designed in step 2, a metal mesh is woven on the outside of the mandrel, and foil is filled to produce a laminated or single-layer, solid or hollow preform according to actual needs;

[0013] Step 5, process selection and pretreatment of blanks: If external pressure reaction blanking is selected, the solid preform needs to be wrapped, placed in a special mold for external pressure reaction, and reacted using external pressure reaction synthesis equipment; if internal pressure reaction blanking is selected, the hollow preform needs to be placed in a special mold for internal pressure reaction, and reacted using internal pressure reaction synthesis equipment. ;

[0014] Step 6, reaction synthesis: reduce the ambient vacuum to below 0.1 Pa by a vacuum pump, heat the preform to a temperature above the melting point of the material with the lower melting point and not higher than the melting point of the material with the higher melting point; at the same time, provide a surface pressure of not less than 1 MPa on the surface of the preform, and maintain it for not less than 0.5 hours, until the two elements undergo sufficient diffusion reaction to completely generate A. x B y Intermetallic compounds;

[0015] Step 7: Processing of the tube blank after forming: Take out the tube blank after reaction synthesis from the mold and perform necessary cutting and grinding and polishing on it.

[0016] The beneficial effects of the present invention are:

[0017] (1) The present invention provides a method for preparing an intermetallic compound seamless tube with a three-dimensional network structure, which uses a metal wire mesh as a raw material for reaction synthesis. The final synthesized metal tube has coarse and fine grain regions that are alternately distributed in the three-dimensional space. The coarse grain region ensures the high strength of the material, and the fine grain region enhances the toughness of the material. At the same time, the alternating coarse and fine grain regions also effectively inhibit the expansion of cracks and significantly enhance the fracture toughness of the material.

[0018] (2) The method for preparing a seamless intermetallic compound tube with a three-dimensional network structure of the present invention uses a metal mesh as a base material. The microstructure of the material after the final reaction synthesis, such as the grain size and distribution form, can be effectively controlled by adjusting parameters such as the wire diameter, the gap between the metal mesh holes, and the mesh type, thereby achieving accurate regulation of the material properties.

[0019] (3) The method for preparing a seamless intermetallic compound tube with a three-dimensional network structure of the present invention uses a metal wire mesh as a reaction matrix of a higher melting point element, and utilizes its continuous weaving characteristics to prepare tube blanks of different diameters and unlimited lengths, and can achieve batch continuous production. In addition, by using hot pressing conditions with a temperature higher than that of the material with a lower melting point and utilizing the fluidity of the liquid metal, the problem of material performance degradation caused by the gap between the foils during the continuous winding process is effectively solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A process roadmap for preparing a seamless intermetallic compound tube having a three-dimensional network structure;

[0021] Figure 2 Schematic diagram of the laminated preform structure;

[0022] Figure 3 Schematic diagram of the single-layer preform structure;

[0023] Figure 4 It is a schematic diagram of the structure of the die for the external pressure reaction synthesis of the intermetallic compound seamless pipe;

[0024] Figure 5 It is a schematic diagram of the structure of the die for the internal pressure reaction synthesis of the intermetallic compound seamless pipe;

[0025] Figure 6 This is a schematic diagram of the structure of the equipment for external pressure reaction synthesis of intermetallic compound seamless pipes;

[0026] Figure 7 This is a schematic diagram of the structure of the internal pressure reaction synthesis equipment for intermetallic compound seamless pipes.

[0027] In the figure: 1-metal foil, 2-1-metal mesh, 2-2-metal wire braided tube, 3-core rod, 4-sleeve, 5-vacuum exhaust port, 6-punch air inlet, 7-air inlet sealing punch, 8-outer mold, 9-support core tube, 10-mold exhaust port, 11-sealing punch, 12-hot isostatic pressing furnace, 13-closed vacuum mold, 14-high-pressure air pump, 15-main pressurizing cylinder, 16-equipment frame, 17-heating furnace, 18-vacuum pump, 19-side pressurizing cylinder. DETAILED DESCRIPTION

[0028] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0029] Example 1: Combination Figure 1 , Figure 2 , Figure 4 , Figure 6 A method for preparing a seamless intermetallic compound tube having a three-dimensional network structure is described, and the specific steps are as follows:

[0030] Step 1: Determine the volume fraction of raw materials: According to the target intermetallic compound A x B y The volume of raw materials required for component calculation, 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 the target intermetallic compound constituent 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. Assuming that A is the element with a higher melting point in the target material, the volume fraction of A is ((x×M A ) / ρ A ) / ((x×M A ) / ρ A +(y×M B ) / ρ B ). Taking NiAl, TiAl, and FeAl alloys as examples, the volume ratio of Ni to Al should be 1:1.51, the volume ratio of Ti to Al should be 1.05:1, and the volume ratio of Fe to Al should be 1:1.40.

[0031] Step 2, determine the reaction matrix. Select the material with higher melting point among the two materials and weave it into a mesh with metal filaments. The wire diameter of the filaments is 0.01-0.5mm, and the mesh gap is 0.01-0.5mm. After weaving, the volume fraction of the metal mesh is the volume fraction calculated in step 1. The material with lower melting point is made of metal foil with a thickness of 0.01-2mm. For NiAl, TiAl, and FeAl alloys, select Ni, Ti, and Fe filaments to weave into a mesh, and select Al foil as the filling material. After weaving, the volume fractions of Ni, Ti, and Fe meshes are 39.84%, 51.22%, and 41.67%, respectively.

[0032] Step 3: Material pretreatment: Use organic solvent ultrasonic cleaning or other methods to pretreat the material surface to remove oil stains.

[0033] Step 4: Preform production: According to the wire diameter, gap and weaving form of the wire mesh designed in step 2, the metal wire mesh is woven, and then it is continuously wound with the metal foil on the mandrel to prepare a preform.

[0034] Step 5: Pretreatment of the blank: Encase the blank and reduce the ambient vacuum to below 0.1 Pa using a vacuum pump through a vacuum exhaust port.

[0035] Step 6: Reaction to form intermetallic compounds. Place the material in a hot isostatic pressing furnace and heat it to a temperature above the melting point of the material with the lower melting point, but not higher than the melting point of the material with the higher melting point. At the same time, provide a surface pressure of not less than 1MPa on the entire surface. Maintain high temperature and high pressure for not less than 0.5 hours until the two elements undergo sufficient diffusion reaction and completely generate A. x B y Intermetallic compounds. For NiAl, TiAl, and FeAl alloys, the sintering temperature is greater than 660°C and less than 1200°C.

[0036] Step 7: Processing of the tube blank after forming. Take out the tube blank after reaction synthesis from the mold, cut the process section, and grind and polish the surface of the tube.

[0037] Metal mesh is used as the raw material for reaction synthesis, and the final synthesized metal tube has alternating coarse-grained and fine-grained regions in the three-dimensional space, which effectively inhibits the expansion of cracks and significantly enhances the fracture toughness of the material; metal mesh is used as the matrix material, and the microstructure of the material after the final reaction synthesis, such as grain size and distribution form, can be effectively controlled by adjusting the wire diameter, wire mesh gap, wire mesh weaving type and other parameters of the metal mesh, thereby achieving accurate regulation of material properties; metal mesh is used as the reaction matrix of higher melting point elements, and its continuous weaving characteristics can be utilized to prepare tube blanks of different diameters and unlimited lengths, and batch continuous production can be achieved; hot pressing conditions with a temperature higher than that of the lower melting point material and the fluidity of the liquid metal are used to effectively solve the problem of material performance degradation caused by the gap between the foils during continuous winding.

[0038] Example 2: Combination Figure 3 It is noted that in step 4, the metal wire is supported by the core rod and continuously braided along the axial direction to directly obtain a continuous tubular metal mesh, and the metal foil directly covers the metal braided tube. The remaining steps are the same as those in Example 1.

[0039] The continuous braiding and winding method for preparing the metal braided tube can provide a certain tension force on the metal wires in the braided tube, effectively ensure the relative position of the metal wires, and improve the dimensional accuracy of the metal tube.

[0040] Example 3: Combination Figure 5 , Figure 7 illustrate.

[0041] In step four, a metal tube is used as a mandrel.

[0042] In step five, Figure 5The structure shown is an internal pressure loading mold, and the mold includes a punch air inlet 6, an air inlet sealing punch, an outer mold, a support core tube, a mold air extraction port, and a sealing punch. The support core tube wrapped with the material is placed in the outer mold, the outer mold is closed, and the punches on both sides are fed so that the support core tube and the support core tube and the outer mold form two independent closed cavities, and the cavity where the material is located is evacuated to a vacuum degree of less than 0.1Pa.

[0043] In step six, use Figure 7 The equipment structure shown includes a closed vacuum mold, a high-pressure air pump, a main pressure cylinder, an equipment frame, a heating furnace, a vacuum pump, and a side pressure cylinder. The main pressure cylinder provides mold clamping force, and the side pressure cylinder provides sealing force. The two work together to fix and seal the mold. The vacuum pump is used to maintain the vacuum degree of the material cavity, and the high-pressure air source provides the internal pressure of the pipe to ensure that the reaction synthesis pressure is not less than 1MPa. Finally, the mold in step 5 is placed in a heating furnace for reaction.

[0044] The remaining steps are the same as those in Example 1.

[0045] The internal pressure loading method of the pipe is adopted to avoid the use of hot isostatic pressing equipment, reduce the difficulty of material wrapping, realize the rapid batch production of parts, and effectively reduce the production cost.

[0046] Embodiment 4: In step six, the mold is heated by induction heating, heating wire heating, etc., and the remaining steps are the same as in embodiment 3.

[0047] The vacuum hot pressing mold is heated by induction heating, heating wire heating, etc., with fast heating speed and low equipment requirements. It can also avoid the limitation of the heating furnace hearth size on the mold size, thereby obtaining large-sized pipe fittings.

Claims

1. A method for preparing a seamless intermetallic compound tube having a three-dimensional network structure, characterized in that: Here are the steps: Step 1: Determine the volume fraction of raw materials: According to the target intermetallic compound A x B y The volume of raw materials required for ingredient calculation; Step 2: Determine the reaction matrix: select the material with a higher melting point among the two materials and weave it into a metal mesh with metal filaments; use a metal foil material with a lower melting point, and the thickness of the foil material is 0.01-2 mm; Step 3: Material pretreatment: Use organic solvent to ultrasonically clean the material surface to remove oil stains; Step 4: Preform production: According to the wire diameter, mesh gap and weaving form of the wire mesh designed in step 2, a metal mesh is woven on the outside of the mandrel, and foil is filled to produce a laminated or single-layer, solid or hollow preform according to actual needs; Step 5, process selection and pretreatment of blanks: When using external pressure reaction to make blanks, the solid preform needs to be wrapped, placed in a special mold for external pressure reaction, and reacted using external pressure reaction synthesis equipment; when using internal pressure reaction to make blanks, the hollow preform needs to be placed in a special mold for internal pressure reaction, and reacted using internal pressure reaction synthesis equipment; Step 6, reaction synthesis: reduce the ambient vacuum to below 0.1 Pa by a vacuum pump, heat the preform to a temperature above the melting point of the material with the lower melting point and not higher than the melting point of the material with the higher melting point; at the same time, provide a surface pressure of not less than 1 MPa on the surface of the preform, and maintain it for not less than 0.5 hours, until the two elements undergo sufficient diffusion reaction to completely generate A. x B y Intermetallic compounds; Step 7: Processing of the tube blank after forming: Take out the tube blank after reaction synthesis from the mold and perform necessary cutting and grinding and polishing on it.

2. The method for preparing an intermetallic compound seamless pipe having a three-dimensional network structure according to claim 1, characterized in that: In step 1, the volume ratio of materials A and B is: (x×M A ) / ρ A :(y×M B ) / ρ B , where x and y are the number of atoms of the target intermetallic compound constituent 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.

3. The method for preparing a seamless intermetallic compound tube having a three-dimensional network structure according to claim 1, characterized in that: In step 2, the wire diameter of the metal mesh is 0.01-0.5 mm, and the mesh gap is 0.01-0.5 mm; Assuming that material A is a material with a high melting point and material B is a material with a low melting point, the volume ratio of the metal mesh to the metal foil is the volume ratio calculated in step one.

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