Aluminum-tungsten-based gradient composite material and preparation method thereof

Abstract

The invention belongs to the technical field of metal-based composite material preparation, and provides an aluminum-tungsten-based gradient composite material and a preparation method thereof. The method comprises the following steps that tungsten powder and aluminum powder are mixed according to different mass percents and then subjected to ball milling and material mixing under argon protection, and six sets of mixed powder are obtained; then carrying out cold press molding, and sequentially overlapping to form a laminated structure; and after the laminated structure is compacted, explosive sintering is conducted under emulsion explosive, a sintered product is subjected to heat treatment, and the aluminum-tungsten-based gradient composite material is obtained. According to the method, the density and the mechanical property of the Al-W-based gradient composite material are remarkably improved. The Al-W powder with different proportions is subjected to cold pressing lamination forming, and then the densification of the gradient structure is completed through explosive sintering. The method disclosed by the invention can be used for efficiently preparing the large-size Al-W-based gradient composite material with different density distributions, can be applied to the field of high-end equipment manufacturing, and has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of metal matrix composites, and particularly relates to an aluminum-tungsten-based gradient composite material and a preparation method thereof. Background Art

[0002] In recent years, with the continuous development of technology, scientific fields such as high-end equipment and national defense security have been key developed. In these scientific fields, there are often complex loading environments. Therefore, the requirements for materials are also constantly increasing, and various alloy materials are also used in the field of high-end equipment manufacturing. Among them, the aluminum-tungsten gradient material (Al-W gradient material) has special material properties and is a functional gradient material composed of two phases of aluminum and tungsten, combining the characteristics of the two metals of aluminum and tungsten. The single-element aluminum metal has good ductility, good electrical and thermal conductivity, and the single-element tungsten metal has high hardness, high melting point, and relatively stable chemical properties. The addition of tungsten in the aluminum-tungsten gradient material significantly improves the strength and hardness of the material. Due to the extremely high melting point of tungsten, the aluminum-tungsten alloy can maintain good stability under high-temperature and high-pressure environments and is not easily deformed or melted, which makes the aluminum-tungsten gradient material have great advantages in the field of high-end manufacturing.

[0003] The Al-W gradient material has the characteristics of large differences in density and melting point. During the preparation process of the Al-W gradient material, various high-pressure unstable and easily phase-changed aluminum-tungsten intermetallic compounds (Al 12 W, Al5W, Al4W, etc.) are easily formed at the Al-W interface, resulting in relatively poor mechanical properties of the Al-W gradient material and unable to fully integrate the properties of the two. In recent years, scholars at home and abroad have carried out a large amount of research work on the preparation of Al-W-based metal gradient materials. The most common methods for preparing Al-W-based metal gradient materials in the early stage were powder hot isostatic pressing method and cold isostatic pressing method. The mechanical properties of the Al-W-based gradient materials prepared by this method were poor, and they were only combined by weak diffusion on the surface. Its compressive strength was less than 150 MPa, and the interface showed brittle fracture, which would eventually lead to cracking when preparing large-size gradient materials. The most common method for preparing Al-W-based gradient materials in recent years is the non-equilibrium preparation method, including mechanical alloying method and non-equilibrium preparation processes of the melt method mainly occur in the powder pretreatment process, while non-equilibrium preparation processes such as severe plastic deformation method, magnetron sputtering method, and selective laser melting method occur in the densification process.

[0004] In the non-equilibrium preparation method, there is an easy problem that the densification sintering temperature is relatively high, resulting in Al in the Al-W-based gradient material 12Intermetallic compounds such as W, Al5W, and Al4W have a high content, poor toughness, low strength, and are prone to defects such as pores and cracks. Or when the strength is high, the tungsten content between Al-W-based gradient materials is low (<50%), and it is impossible to obtain an Al-W-based composite material with a high tungsten content. Currently, conventional preparation methods cannot control the melting point difference and phase formation between aluminum and tungsten materials, and there is an urgent need to develop new preparation methods to obtain Al-W-based gradient materials with high density, excellent mechanical properties, and controllable phases.

[0005] Currently, among the patents related to Al-W-based composite materials, Patent No. CN 105908020 B discloses a preparation method of an aluminum-tungsten composite material. In this patent, a semi-solid casting technology and a mechanical stirring method are used to prepare the Al-W-based composite material. In this method, the elements other than Al-W are relatively numerous, resulting in a low purity of the Al-W-based composite material, and the W content is low and cannot form a gradient composite material. Therefore, it is difficult to ensure the strength and toughness of the Al-W-based composite material. Patent No. CN 102703768 B discloses an aluminum-tungsten composite material and its preparation method. In this patent, aluminum plates and tungsten metal particles are used as raw materials, and the aluminum-tungsten composite material is prepared by means of accumulative roll bonding welding. In this method, there are a large number of intermetallic compounds, and the W content is low and cannot form a gradient composite material.

[0006] Therefore, it is of great significance to provide a method for regulating the melting point difference and phase formation between Al-W-based gradient materials and preparing an aluminum-tungsten-based gradient composite material with excellent mechanical properties and high density. Summary of the Invention

[0007] The purpose of the present invention is to provide an aluminum-tungsten-based gradient composite material and its preparation method to overcome the deficiencies of the prior art. The aluminum-tungsten-based gradient composite material of the present invention has excellent mechanical properties and high density.

[0008] To achieve the above-mentioned invention purpose, the present invention provides the following technical solutions: The present invention provides a preparation method of an aluminum-tungsten-based gradient composite material, which comprises the following steps: 1) Mix tungsten powder and aluminum powder according to different mass percentages, and then ball-mill and mix them under argon protection to obtain six groups of mixed powders; 2) Cold-press and form the six groups of mixed powders respectively to obtain six groups of composite material blanks; 3) Stack the six groups of composite material blanks from bottom to top in ascending order of tungsten content to form a laminated structure; 4) After compacting the laminated structure, perform explosive sintering under emulsified explosive to obtain a sintered product; 5) Heat-treat the sintered product to obtain an aluminum-tungsten-based gradient composite material.

[0009] Preferably, in the first group of mixed powder, the mass percentage of Al powder is 0% and the mass percentage of W powder is 100%; in the second group of mixed powder, the mass percentage of Al powder is 18 - 22% and the mass percentage of W powder is 78 - 82%; in the third group of mixed powder, the mass percentage of Al powder is 38 - 42% and the mass percentage of W powder is 58 - 62%; in the fourth group of mixed powder, the mass percentage of Al powder is 58 - 62% and the mass percentage of W powder is 38 - 42%; in the fifth group of mixed powder, the mass percentage of Al powder is 78 - 82% and the mass percentage of W powder is 18 - 22%; in the sixth group of mixed powder, the mass percentage of Al powder is 100% and the mass percentage of W powder is 0%.

[0010] Preferably, the time for ball milling and mixing in step 1) is 1.5 - 2.5 h; the particle sizes of the tungsten powder and aluminum powder are independently 2 - 20 μm.

[0011] Preferably, the pressure for cold pressing and forming in step 2) is 280 - 320 MPa.

[0012] Preferably, the mixed powders corresponding to the six groups of composite material green blanks stacked from bottom to top in step 3) are the sixth group of mixed powder, the fifth group of mixed powder, the fourth group of mixed powder, the third group of mixed powder, the second group of mixed powder, and the first group of mixed powder respectively.

[0013] Preferably, the pressure for compaction in step 4) is 90 - 110 MPa.

[0014] Preferably, the time for explosion sintering in step 4) is 1 - 10 ms, and the pressure for explosion sintering is 5 - 30 GPa.

[0015] Preferably, the temperature for heat treatment in step 5) is 300 - 600 °C, and the time for heat treatment is ≥ 30 min.

[0016] The present invention also provides an aluminum-tungsten-based gradient composite material prepared by the preparation method of the aluminum-tungsten-based gradient composite material.

[0017] The beneficial effects of the present invention include the following aspects: 1) The present invention provides a preparation method for an aluminum-tungsten-based gradient composite material through a powder laying method and an explosion sintering method. The method of the present invention significantly improves the density and mechanical properties of the Al-W-based gradient composite material. By cold pressing and laminating different ratios of Al-W powders and then completing the densification of the gradient structure through explosion sintering. The explosion sintering method has a short time, a low sintering temperature, a large sintering pressure, and the sintering pressure increases layer by layer, thereby effectively reducing the formation of intermetallic compounds, maintaining the characteristics of the raw materials, and significantly improving the strength and toughness of the material.

[0018] 2) By regulating the melting point difference and phase formation between Al-W-based gradient materials and laminating Al-W-based gradient materials with different densities, the present invention prepares large-sized Al-W-based gradient materials with accurate density distribution. When preparing Al-W-based gradient materials by explosive sintering method, the amount of intermetallic compound formed is small, which is beneficial to maintaining the high toughness of Al and the high strength characteristics of W. The explosive sintering time is extremely short, and due to the density and composition differences of different layers, the explosive shock wave forms different pressure distributions in each layer, enabling the material to achieve densification layer by layer. Vacuum heat treatment can optimize the microstructure of Al-W-based composites, reduce the formation of microcracks and pores, and promote the densification of the material through heat treatment to further improve the strength and toughness of Al-W-based gradient composites.

[0019] 3) The method of the present invention can efficiently prepare large-sized Al-W-based gradient composites with different density distributions, which can be applied to the field of high-end equipment manufacturing and has broad application prospects. Brief Description of the Drawings

[0020] Figure 1 It is a schematic diagram of the sealing of the explosive sintering die of the present invention; Figure 2 It is a relationship diagram of W content and pressure when preparing Al-W-based gradient composites with different kinds of explosives. Detailed Embodiments

[0021] The present invention provides a method for preparing an Al-W-based gradient composite material, which comprises the following steps: 1) Mix tungsten powder and aluminum powder according to different mass percentages, and then ball-mill and mix them under argon protection respectively to obtain six groups of mixed powders; 2) Cold-press and form the six groups of mixed powders respectively to obtain six groups of composite material blanks; 3) Stack the six groups of composite material blanks from bottom to top in the order of increasing tungsten content to form a laminated structure; 4) After compacting the laminated structure, carry out explosive sintering under emulsified explosive to obtain a sintered product; 5) Heat-treat the sintered product to obtain an Al-W-based gradient composite material.

[0022] In the present invention, the mass percentage of Al powder in the first group of mixed powder is 0%, and the mass percentage of W powder is 100%; in the second group of mixed powder, the mass percentage of Al powder is preferably 18-22%, more preferably 19-21%, and most preferably 20%, and the mass percentage of W powder is preferably 78-82%, more preferably 79-81%, and most preferably 80%; in the third group of mixed powder, the mass percentage of Al powder is preferably 38-42%, more preferably 39-41%, and most preferably 40%, and the mass percentage of W powder is preferably 58-62%, more preferably 59-61%, and most preferably 60%; in the fourth group of mixed powder, the mass percentage of Al powder is preferably 58-62%, more preferably 59-61%, and most preferably 60%, and the mass percentage of W powder is preferably 38-42%, more preferably 39-41%, and most preferably 40%; in the fifth group of mixed powder, the mass percentage of Al powder is preferably 78-82%, more preferably 79-81%, and most preferably 80%, and the mass percentage of W powder is preferably 18-22%, more preferably 19-21%, and most preferably 20%; in the sixth group of mixed powder, the mass percentage of Al powder is 100%, and the mass percentage of W powder is 0%.

[0023] In the present invention, the time of ball milling and mixing in step 1) is preferably 1.5-2.5 h, more preferably 1.8-2.2 h, and most preferably 2 h; the particle sizes of the tungsten powder and aluminum powder are independently preferably 2-20 μm, more preferably 2 μm, 10 μm, and 20 μm.

[0024] In the present invention, pure argon is filled during the ball milling and mixing process in step 1) to prevent powder oxidation.

[0025] In the present invention, the pressure of cold pressing and forming in step 2) is preferably 280-320 MPa, more preferably 290-310 MPa, and most preferably 300 MPa; cold pressing and forming is preferably carried out in a tablet press, and cold pressing and forming can improve the initial density of the green compact.

[0026] In the present invention, the mixed powders corresponding to the six groups of composite material green compacts stacked from bottom to top in step 3) are preferably the sixth group of mixed powder, the fifth group of mixed powder, the fourth group of mixed powder, the third group of mixed powder, the second group of mixed powder, and the first group of mixed powder respectively.

[0027] In the present invention, the pressure of compaction in step 4) is preferably 90-110 MPa, more preferably 95-105 MPa, and most preferably 100 MPa.

[0028] In the present invention, the time of the explosive sintering in step 4) is preferably 1 - 10 ms, more preferably 3 - 8 ms, still more preferably 5 - 6 ms, and the pressure of the explosive sintering is preferably 5 - 30 GPa.

[0029] The sealing schematic diagram of the explosive sintering die of the present invention is as Figure 1 shown, which can densify the gradient structure under the propulsion of the explosive pressure.

[0030] In the present invention, during the explosive sintering process, the pressure of each layer increases layer by layer from bottom to top to achieve effective sintering of different layers of Al-W based composites and prepare high-strength and tough Al-W based gradient composites; the explosive sintering is carried out in a polyvinyl chloride pipe (PVC pipe), and the explosive sintering realizes the dense sintering of the Al-W based composites.

[0031] There is a huge difference in melting points between aluminum and tungsten metals. When the tungsten content in the Al-W based composites is higher, the sintering difficulty is greater. With the increase of the tungsten content, the explosive sintering pressure needs to be significantly increased. Therefore, the pressures of the powder explosive sintering process of Al-W based composite blanks with different compositions and porosities are significantly different. The explosive shock wave acts on the die to carry out explosive sintering on the Al-W laminated blank; the explosive sintering time is extremely short, and due to the density and composition differences of different layers, the explosive shock wave forms different pressure distributions in each layer.

[0032] The present invention uses an explosive method to prepare Al-W based gradient composites, and the explosive method also belongs to a kind of non-equilibrium method. The Al-W based gradient composites are obtained by explosive sintering, and then the microstructure of the Al-W based gradient composites is regulated by heat treatment. During the conduction process of the explosive shock wave, the explosive sintering pressure of each layer is different, resulting in the pressure increasing gradually with the density during the preparation of the Al-W based gradient materials. This characteristic is suitable for preparing high-tungsten-content Al-W based gradient composites with densification and different density distributions. When using the explosive method to prepare Al-W based gradient composites, wavy interfaces are likely to occur between laminated materials with different densities, but the wave width is small, and the organizational structure of the Al-W based gradient composites can be precisely regulated by adjusting the explosive parameters and heat treatment process parameters.

[0033] In the present invention, the temperature of the heat treatment in step 5) is preferably 300 - 600 °C, more preferably 350 - 550 °C, still more preferably 400 - 500 °C, and the time of the heat treatment is preferably ≥30 min, more preferably ≥35 min, still more preferably ≥40 min.

[0034] The present invention also provides the Al-W based gradient composites prepared by the preparation method of the Al-W based gradient composites.

[0035] The technical solution provided by the present invention will be described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0036] In the embodiment, the Al powder is composed of Al powder with a particle size of 2 μm, Al powder with a particle size of 10 μm, and Al powder with a particle size of 20 μm, which are mixed in a mass ratio of 3:2:1; the W powder is composed of W powder with a particle size of 2 μm, W powder with a particle size of 10 μm, and W powder with a particle size of 20 μm, which are mixed in a mass ratio of 1:2:3.

[0037] Example 1

[0038] Tungsten powder and aluminum powder are mixed in different mass percentages to obtain six groups of powders. The six groups of powders are respectively put into a ball mill and milled (at a rotation speed of 200 rpm) for 2 h in a pure argon atmosphere to ensure uniform mixing of the Al-W powder, obtaining six groups of mixed powders. In the first group of mixed powders, the mass percentage of Al powder is 0%, and the mass percentage of W powder is 100%; in the second group of mixed powders, the mass percentage of Al powder is 20%, and the mass percentage of W powder is 80%; in the third group of mixed powders, the mass percentage of Al powder is 40%, and the mass percentage of W powder is 60%; in the fourth group of mixed powders, the mass percentage of Al powder is 60%, and the mass percentage of W powder is 40%; in the fifth group of mixed powders, the mass percentage of Al powder is 80%, and the mass percentage of W powder is 20%; in the sixth group of mixed powders, the mass percentage of Al powder is 100%, and the mass percentage of W powder is 0%.

[0039] The six groups of mixed powders are respectively put into a tablet press and cold-pressed at 300 MPa for 5 min to form six groups of composite material blanks with different densities. The six groups of composite material blanks are arranged from bottom to top (from bottom to top are the sixth group of composite material blanks, the fifth group of composite material blanks, the fourth group of composite material blanks, the third group of composite material blanks, the second group of composite material blanks, and the first group of composite material blanks, and the masses of the six groups of composite material blanks are equal) in layers in an explosive sintering ultra-high-strength steel mold to form a multi-layer laminated structure.

[0040] The mold containing the multi-layered laminated structure is sealed, and a pressure of 100 MPa is applied in a tablet press for compaction to ensure close contact between each layer of the green body and the mold. The mold containing the compacted laminated structure is placed in a PVC pipe with an outer diameter of 110 mm. The pipe is filled with rock emulsion explosive No. 42. The height of the rock emulsion explosive No. 42 charge in the PVC pipe is 300 mm, and the explosion sintering time is 5 ms. The explosive is detonated at a safe distance, and the explosion shock wave acts on the mold to perform explosion sintering on the Al-W laminated green body. Due to the density and composition differences of different layers, the explosion shock wave forms different pressure distributions in each layer (forming a pressure gradient that increases layer by layer from 5 to 25 GPa from bottom to top through explosion, overcoming the sintering barriers of different layers of the gradient material), enabling the material to achieve layer-by-layer densification.

[0041] After the explosion sintering is completed, the sintered material is placed in a vacuum furnace for heat treatment. The vacuum degree is 0.1 Pa, the heat treatment temperature is 500 °C, and the heat treatment time is 35 min to obtain an aluminum-tungsten-based gradient composite material.

[0042] Example 2

[0043] Tungsten powder and aluminum powder are mixed in different mass percentages to obtain six groups of powders. The six groups of powders are respectively put into a ball mill and milled (rotation speed is 200 rpm) in a pure argon atmosphere for 2.5 h to ensure uniform mixing of the Al-W powders, obtaining six groups of mixed powders. In the first group of mixed powders, the mass percentage of Al powder is 0%, and the mass percentage of W powder is 100%; in the second group of mixed powders, the mass percentage of Al powder is 20%, and the mass percentage of W powder is 80%; in the third group of mixed powders, the mass percentage of Al powder is 40%, and the mass percentage of W powder is 60%; in the fourth group of mixed powders, the mass percentage of Al powder is 60%, and the mass percentage of W powder is 40%; in the fifth group of mixed powders, the mass percentage of Al powder is 80%, and the mass percentage of W powder is 20%; in the sixth group of mixed powders, the mass percentage of Al powder is 100%, and the mass percentage of W powder is 0%.

[0044] The six groups of mixed powders are respectively put into a tablet press and cold-pressed and formed at 310 MPa, with a pressure holding time of 5 min, forming six groups of composite material green bodies with different densities. In the order of increasing tungsten content, the six groups of composite material green blanks are placed layer by layer from bottom to top (from bottom to top are the sixth group of composite material green blanks, the fifth group of composite material green blanks, the fourth group of composite material green blanks, the third group of composite material green blanks, the second group of composite material green blanks, and the first group of composite material green blanks, and the masses of the six groups of composite material green blanks are equal) into an explosion sintering ultra-high-strength steel mold to form a multi-layered laminated structure.

[0045] The mold containing the multi-layered laminate structure is capped and compacted under a pressure of 95 MPa in a tablet press to ensure close contact between each layer of the green body and the mold. The mold containing the compacted laminate structure is placed in a PVC pipe with an outer diameter of 110 mm, and the pipe is filled with No. 42 rock emulsion explosive. The height of the No. 42 rock emulsion explosive charge column in the PVC pipe is 320 mm, and a layer of sodium polyacrylate hydrogel is coated on the seal to make the explosion sintering time 8 ms. The explosive is detonated at a safe distance, and the explosion shock wave acts on the mold to perform explosion sintering on the Al-W laminate green body. Due to the density and composition differences of different layers, the explosion shock wave forms different pressure distributions in each layer (forming a pressure gradient increasing layer by layer from bottom to top of 6-28 GPa through explosion, overcoming the sintering barriers of different layers of gradient materials), enabling the material to achieve layer-by-layer densification.

[0046] After the explosion sintering is completed, the sintered material is placed in a vacuum furnace for heat treatment. The vacuum degree is 0.1 Pa, the heat treatment temperature is 400 °C, and the heat treatment time is 40 min to obtain an aluminum-tungsten-based gradient composite material.

[0047] Example 3

[0048] The six groups of composite material green bodies forming the multi-layered laminate structure in Example 1 are changed to the mass ratio of the green bodies of each layer from bottom to top being 1:1.2:1.4:1.6:1.8:2, forming an Al-W-based gradient composite material with a gradually increasing density layer by layer. Other process parameters are the same as those in Example 1, and a gradient composite material with higher strength and more uniform properties can be obtained.

[0049] The aluminum-tungsten-based gradient composite material of this example further improves the densification and mechanical properties of the gradient composite material.

[0050] Example 4

[0051] During the explosion sintering process, the laminated materials with different compositions form a wavy interface structure under the action of pressure. On the basis of Example 1, by adjusting the charge column height and a small amount of filler, and other process parameters being the same as those in Example 1, a gradient composite material with higher strength and more uniform properties can be obtained.

[0052] Comparative Example 1 The No. 42 rock emulsion explosive in Example 1 is replaced with TNT and ammonium nitrate fuel oil explosive respectively, and other conditions are the same as those in Example 1.

[0053] The relationship diagram of the W content and pressure when preparing the aluminum-tungsten-based gradient composite material with different explosives is as Figure 2As shown, in the Al-W based gradient composite material, the tungsten content gradually decreases from top to bottom for each layer. The temperature differences required for densifying each layer are very large. The first layer is pure tungsten powder (melting point: 3410 °C), and the sixth layer is pure aluminum powder (melting point: 660 °C). In a uniform thermal field, a very large temperature gradient is required to densify each layer of the Al-W based gradient composite material, and pure liquid-phase sintering cannot be used either. Because during the sintering process, tungsten particles will settle and the gradient effect cannot be achieved. Figure 2 To use the gradient pressure generated during explosive sintering to replace the difficult-to-achieve temperature gradient, the gradient pressure is adopted to weaken the physical property differences of the sintering barriers between different layers of the gradient material. Figure 2 The pressure gradients formed inside the aluminum-tungsten gradient composite material prepared with different explosives and the aluminum-tungsten gradient composite material prepared by non-explosive sintering.

[0054] The present invention applies the explosive method to the preparation process of the Al-W based gradient composite material, controls the pressure required for each layer of the Al-W green body during explosive sintering, so that when the Al-W based gradient composite material is prepared by explosive sintering, the interfaces of the particles have almost no diffusion or only a small degree of diffusion, and the amount of intermetallic compound formed is small, which is beneficial to maintaining the good characteristics of the raw materials, and solves the problem of excessive content of intermetallic compounds existing in the non-equilibrium preparation method. The present invention has the characteristics of short sintering time, low overall sintering temperature, large sintering pressure (GPa level) and the pressure gradually increases with the density of the sintered material during the sintering process.

[0055] The preparation method of the present invention realizes the integrated preparation of the Al-W based gradient composite material with different compositions and density distributions through the processes of layered powder laying and explosive sintering. The aluminum-tungsten based gradient composite material has good strength and toughness and density, and greatly reduces the amount of intermetallic compound formed.

[0056] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of an aluminum-tungsten-based gradient composite material, characterized in that It includes the following steps: 1) Tungsten powder and aluminum powder are mixed according to different mass percentages and then ball-milled and mixed under argon protection respectively to obtain six groups of mixed powders; 2) The six groups of mixed powders are respectively cold-pressed into six groups of composite billets; 3) The six groups of composite billets are stacked from bottom to top in ascending order of tungsten content to form a laminated structure; 4) After the laminated structure is compacted, it is subjected to explosive sintering under emulsion explosive to obtain a sintered product; 5) The sintered product is heat-treated to obtain an aluminum-tungsten-based gradient composite material.

2. The preparation method of the aluminum-tungsten-based gradient composite material according to claim 1, wherein In the first group of mixed powders, the mass percentage of Al powder is 0% and the mass percentage of W powder is 100%; in the second group of mixed powders, the mass percentage of Al powder is 18 - 22% and the mass percentage of W powder is 78 - 82%; in the third group of mixed powders, the mass percentage of Al powder is 38 - 42% and the mass percentage of W powder is 58 - 62%; in the fourth group of mixed powders, the mass percentage of Al powder is 58 - 62% and the mass percentage of W powder is 38 - 42%; in the fifth group of mixed powders, the mass percentage of Al powder is 78 - 82% and the mass percentage of W powder is 18 - 22%; in the sixth group of mixed powders, the mass percentage of Al powder is 100% and the mass percentage of W powder is 0%.

3. The preparation method of the aluminum-tungsten-based gradient composite material according to claim 1 or 2, characterized in that, In step 1), the time of the ball-milling and mixing is 1.5 - 2.5 h; the particle sizes of the tungsten powder and the aluminum powder are independently 2 - 20 μm.

4. The preparation method of the aluminum-tungsten-based gradient composite material according to claim 3, wherein In step 2), the pressure of the cold pressing is 280 - 320 MPa.

5. The preparation method of the aluminum-tungsten-based gradient composite material according to claim 4, characterized in that, In step 3), the mixed powders corresponding to the six groups of composite billets stacked from bottom to top are the sixth group of mixed powders, the fifth group of mixed powders, the fourth group of mixed powders, the third group of mixed powders, the second group of mixed powders, and the first group of mixed powders respectively.

6. The preparation method of the aluminum-tungsten-based gradient composite material according to claim 5, wherein In step 4), the pressure of the compaction is 90 - 110 MPa.

7. The preparation method of the aluminum-tungsten-based gradient composite material according to claim 5 or 6, characterized in that, In step 4), the time of the explosive sintering is 1 - 10 ms, and the pressure of the explosive sintering is 5 - 30 GPa.

8. The preparation method of the aluminum-tungsten-based gradient composite material according to claim 7, wherein In step 5), the temperature of the heat treatment is 300 - 600 °C, and the time of the heat treatment is ≥ 30 min.

9. An aluminum-tungsten-based gradient composite material prepared by the preparation method of the aluminum-tungsten-based gradient composite material according to any one of claims 1 - 8.

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