An aluminum matrix composite and a method for producing the same

Abstract

The application provides an aluminum matrix composite material and a preparation method thereof, and mainly relates to the technical field of aluminum matrix alloys.The aluminum matrix composite material provided by the application comprises an aluminum alloy matrix and a reinforcing material dispersed in the aluminum alloy matrix, and the reinforcing material is composed of a silicon carbide particle core and a sericite layer wrapped outside the silicon carbide particle core.The core-shell structure reinforcing material formed by introducing the mica powder wrapped silicon carbide particles into the aluminum alloy matrix utilizes the good mechanical properties of the silicon carbide itself, and the flexible sericite layer wrapped outside the silicon carbide particles can hinder crack propagation, so that the strength and toughness of the composite material are improved, and the aluminum matrix composite material has more excellent mechanical properties while maintaining the light weight and low expansion characteristics of the existing silicon carbide particle reinforced aluminum matrix composite material.

Description

Technical Field

[0001] This invention belongs to the field of aluminum-based alloy technology, specifically relating to an aluminum-based composite material and its preparation method. Background Technology

[0002] Aluminum-based alloys have achieved comprehensive properties that cannot be obtained from elemental aluminum. They fully utilize the complementary and synergistic effects of the reinforcing particles (silicon carbide particles) and the aluminum matrix, thus possessing excellent properties such as lightweight, high strength, and low expansion. They are currently one of the most promising aerospace materials.

[0003] As spacecraft develop towards higher performance and higher reliability, their key components are required to have better mechanical properties while maintaining basic functional characteristics. However, existing technologies cannot achieve simultaneous improvement of expansion coefficient and mechanical properties by simply adjusting the silicon carbide content in composite materials.

[0004] In their paper "Mechanical Properties and Wear Resistance of Hybrid Aluminum Matrix Composites," Rajmohan et al. improved the tensile strength and hardness of aluminum matrix composites by introducing 10% silicon carbide particles and 3% or 6% mica powder into Al356 aluminum alloy. They also found that increasing the mica content improved the wear resistance of the composite. Mica with an average size of 45 μm was added to the Al356 alloy as a reinforcement, uniformly distributed in granular form on the matrix. The layered structure and self-lubricating properties of mica improved the wear resistance of the composite. However, the large-particle layered structure of mica resulted in weak interlayer bonding and a large coefficient of thermal expansion, which reduced the mechanical properties of the composite. Consequently, the tensile strength of this aluminum matrix composite remained low, and it was impossible to further improve the mechanical properties while maintaining a low coefficient of thermal expansion. Summary of the Invention

[0005] The purpose of this invention is to provide an aluminum-based composite material that has a low coefficient of thermal expansion while improving the mechanical properties of the aluminum-based composite material.

[0006] The second objective of this invention is to provide a method for preparing the above-mentioned aluminum-based composite material.

[0007] To achieve the above objectives, the technical solution of the aluminum-based composite material of the present invention is as follows:

[0008] An aluminum-based composite material includes an aluminum alloy matrix and a reinforcing material dispersed in the aluminum alloy matrix, said reinforcing material consisting of a silicon carbide particle core and a sericite layer surrounding the silicon carbide particle core.

[0009] The aluminum-based composite material provided by this invention is a core-shell structure reinforcing material formed by introducing a sericite layer to encapsulate silicon carbide particles in an aluminum alloy matrix. Utilizing the good mechanical properties of silicon carbide itself, and with the sericite forming a flexible connecting bridge between the aluminum alloy matrix and the silicon carbide particles, the flexible sericite layer encapsulating the silicon carbide particles can hinder crack propagation under load and stress during the service life of the composite material. This can synergistically strengthen and toughen the aluminum alloy, improve the strength and toughness of the composite material, and make the aluminum-based composite material have better mechanical properties while maintaining the lightweight and low expansion characteristics of existing silicon carbide particle-reinforced aluminum-based composite materials.

[0010] To further improve the strength and toughness of the composite material, preferably, the silicon carbide particles have a particle size of 10-15 μm, and the sericite layer is formed of sheet-like sericite with a sheet diameter of 3-5 μm. When sheet-like flexible sericite encapsulates silicon carbide particles to form a core-shell structure as a reinforcing material, it further hinders crack propagation under load and stress during the service life of the composite material, thereby improving the strength and toughness of the composite material.

[0011] The Mg element in the aluminum alloy can form a uniform MgAl2O4 micro-region reaction layer with the mica outside some silicon carbide particles, thereby improving the wettability and bonding strength between the silicon carbide particles and the aluminum matrix. Preferably, the aluminum alloy is an Al-Cu-Mg alloy, which includes 3.5~4.5% Cu and 1.5~2% Mg by mass.

[0012] To further improve the low-expansion characteristics and mechanical properties of aluminum-based composite materials, preferably, the mass ratio of silicon carbide to sericite is 8~10:1.

[0013] Preferably, the total mass of the silicon carbide and sericite is 10% to 40% of the aluminum-based composite material.

[0014] The technical solution of the preparation method of the aluminum-based composite material of the present invention is as follows:

[0015] A method for preparing an aluminum-based composite material includes the following steps: 1) ball milling a mixture of silicon carbide particles and sericite powder to obtain silicon carbide particles coated with sericite powder; 2) ball milling the silicon carbide particles coated with sericite powder and flake aluminum alloy powder to obtain an aluminum-based composite material by pressing and sintering.

[0016] The method for preparing aluminum-based composite materials provided by the present invention involves obtaining silicon carbide particles coated with mica powder by ball milling, and then obtaining aluminum-based composite materials with excellent mechanical properties by sintering and heat treatment. The preparation method is simple and low in cost.

[0017] To make the mica powder coating on the surface of silicon carbide particles more uniform, preferably, the ball milling in step 1) includes wet ball milling and dry ball milling, wherein the wet ball milling time is 20~24h and the dry ball milling time is 4~6h.

[0018] To further improve the sintering bonding strength of aluminum-based composite materials, preferably, the sintering in step 2) is high-temperature sintering or hot-pressing sintering. The high-temperature sintering includes four-stage high-temperature sintering, which includes heat preservation treatment at 120~180℃, 280~320℃, 430~480℃ and 540~560℃ respectively.

[0019] To further densify the sintered aluminum-based composite material and improve its mechanical properties, preferably, after high-temperature sintering, hot deformation densification and heat treatment are performed. The hot deformation densification is hot extrusion, which is carried out after holding at 470-490°C for 2-3 hours, with an extrusion ratio of 15-25:1. More preferably, the extrusion ratio is 15-20:1.

[0020] To more efficiently improve the mechanical properties of aluminum-based composite materials, preferably, the heat treatment includes solution treatment and aging treatment, wherein the solution treatment is held at 500~510℃ for 2~4 hours, and the aging treatment is aged at 175~180℃ for 3~12 hours. Attached Figure Description

[0021] Figure 1 This is a transmission electron microscope (TEM) image of the aluminum-based composite material of Example 1 of the present invention. Detailed Implementation

[0022] The technical solution of the present invention will be further described below with reference to specific embodiments. Unless otherwise specified, the chemical reagents involved in the following embodiments are all commercially available conventional products.

[0023] An aluminum-based composite material includes an aluminum alloy matrix and a reinforcing material dispersed in the aluminum alloy matrix, said reinforcing material consisting of a silicon carbide particle core and a sericite layer surrounding the silicon carbide particle core.

[0024] In a specific embodiment, the aluminum-based composite material is composed of aluminum alloy, silicon carbide particles with a mass fraction of 10-35%, and sericite with a mass fraction of 1-4%.

[0025] A method for preparing an aluminum-based composite material includes the following steps: 1) ball milling a mixture of silicon carbide particles and sericite powder to obtain silicon carbide particles coated with sericite powder; 2) ball milling the silicon carbide particles coated with sericite powder and flake aluminum alloy powder to obtain an aluminum-based composite material by pressing and sintering.

[0026] In a specific embodiment, the silicon carbide particles and sericite need to be surface cleaned before ball milling. The surface cleaning includes the following steps: S1: the silicon carbide particles are acid-washed with hydrofluoric acid, then washed with distilled water, filtered, and dried in a vacuum drying oven; S2: the sericite powder is washed with deionized water and then ultrasonically cleaned, and the silicon carbide particles obtained in S1 are added according to the mass ratio, and ultrasonic cleaning is continued, filtered, and dried in a vacuum drying oven to obtain a mixed powder of sericite and silicon carbide.

[0027] In a specific embodiment, the volume percentage of hydrofluoric acid in step S1 is 5-10%.

[0028] In a specific embodiment, the ultrasonic cleaning time after adding silicon carbide particles in step S2 is 0.3~1h, preferably 0.5h.

[0029] In a specific embodiment, the ball milling of silicon carbide particles and sericite powder includes wet ball milling and high-energy dry ball milling of the mixed powder of sericite and silicon carbide obtained after surface cleaning.

[0030] In a specific embodiment, the wet ball milling uses agate balls as grinding balls and ethanol as a dispersant for the mixed powder of mica powder and silicon carbide particles. The milling time is 20-24 hours, with forward and reverse rotation every 0.5-1 hour during the milling process. After milling, the mixture is dried in a vacuum drying oven for more than 12 hours to remove the dispersant. The high-energy dry ball milling is performed for 4-6 hours to form silicon carbide particles coated with sericite powder, which serve as a reinforcing material with a core-shell structure.

[0031] In a specific embodiment, the sheet-like aluminum alloy is formed by ball milling aluminum alloy powder for 20-24 hours.

[0032] In a specific embodiment, the sheet-like aluminum alloy powder is a sheet-like Al-Cu-Mg alloy powder, which is composed of Al and Cu with a mass fraction of 3.5~4.5% and Mg of 1.5~2%.

[0033] In a specific embodiment, the silicon carbide particles coated with sericite powder and the flake aluminum alloy powder are ball-milled using a wet ball milling method, with a ball milling speed of 150–250 r / min and a ball milling time of 12–16 h.

[0034] In a specific embodiment, silicon carbide particles coated with sericite powder and flake aluminum alloy powder are ball-milled and mixed evenly, and then cold-pressed into a blank. The cold-pressed blank includes segmented pressing and segmented depressurization. The cold-pressed blank includes: first holding the pressure at 100~150MPa for 10~20s; then holding the pressure at 240~280 MPa for 10~20s; then depressurizing to 100~150MPa and holding the pressure for 10~20s; and finally completely depressurizing.

[0035] In a specific implementation, the four-stage high-temperature sintering involves holding at 120~180℃, 280~320℃, and 430~480℃ for 15~45 minutes respectively, and then holding at 540~560℃ for 3~6 hours. The heating rate is 2~3℃ / min, and the furnace is cooled after the high-temperature sintering is completed.

[0036] In a specific embodiment, the hot pressing sintering is vacuum hot pressing sintering with a vacuum degree of 0.2~0.4 Pa. The specific method of hot pressing sintering is as follows: under vacuum conditions, a pressure of 50~90 MPa is applied to the mixed powder, and the temperature is raised to 430~470℃ at a heating rate of 2~4℃ / min and held at pressure and temperature for 50~70 min; then the pressure is increased to 120~150 MPa, and the temperature is continued to rise to 530~570℃ and held at pressure and temperature for 3~5 h. After depressurization, the powder is cooled to room temperature in the furnace.

[0037] In a specific embodiment, the extrusion rate of the hot extrusion is 1~2 mm / s.

[0038] In a specific embodiment, the solution treatment involves holding at 500-510℃ for 2-4 hours, followed by water quenching at 50-70℃. The aging treatment involves aging at 175-180℃ for 3-12 hours, followed by air cooling to room temperature.

[0039] I. Specific Embodiments of the Preparation Method of the Aluminum-Based Composite Material of the Present Invention

[0040] Example 1

[0041] The method for preparing the aluminum-based composite material in this embodiment includes the following steps:

[0042] 1) Silicon carbide particles (10 μm in diameter) were acid-washed with a 5% (v / v) hydrofluoric acid solution, then washed with distilled water, filtered, and dried in a vacuum drying oven to obtain cleaned silicon carbide particles; sericite powder (3 μm in diameter) was washed twice with deionized water, deionized water was added to the cleaned mica powder for ultrasonic cleaning, and the cleaned silicon carbide particles were added at a mass ratio of 10:1. Ultrasonic treatment was continued for 0.5 h, filtered, and dried in a vacuum drying oven to obtain a mixed powder A of sericite powder and silicon carbide particles;

[0043] 2) Use agate balls as grinding balls to ball mill the mixed powder A obtained in step 1). Add ethanol as a dispersant to the mixed powder A of sericite powder and silicon carbide particles and ball mill for 20 hours. During ball milling, rotate forward and backward every 0.5 hours. After ball milling, dry in a vacuum drying oven for 13 hours to remove the dispersant, and then dry mill at high energy for 4 hours to form silicon carbide particles with sericite powder on the surface.

[0044] 3) The Al-Cu-Mg alloy powder is composed of Al and Cu with a mass fraction of 3.5% and Mg of 1.5%. The Al-Cu-Mg alloy powder is ball-milled for 20 hours to form flake Al-Cu-Mg alloy powder. The flake Al-Cu-Mg alloy powder and the silicon carbide particles with mica powder coating from step 2) are then wet-milled at a ball milling speed of 150-250 r / min for 12 hours to obtain a mixed powder B of flake Al-Cu-Mg alloy powder and silicon carbide particles with mica powder coating.

[0045] 4) The mixed powder B obtained in step 3) is cold-pressed into a preform. The cold pressing of the preform includes segmented pressurization and segmented depressurization. The first segment is pressurized to 130MPa and held for 15s. The second segment is increased to the maximum pressure of 260MPa and held for 20s. When depressurizing, the pressure is first reduced to 150MPa and held for 15s, and then the pressure is completely released to obtain the preform of aluminum-based composite material.

[0046] 5) The preform obtained in step 4) is vacuum sintered in a vacuum annealing furnace at a heating rate of 3℃ / min. It is held at 150℃, 300℃ and 450℃ for 30 min respectively, and then raised to the maximum sintering temperature of 550℃ and held for 4 h. It is then cooled with the furnace to obtain the sintered preform of aluminum-based composite material.

[0047] 6) The sintered billet obtained in step 5) is hot extruded. Before extrusion, it is kept at 480℃ for 2 hours. The extrusion speed is 1 mm / s and the extrusion ratio is 16:1 to obtain a densified hot extruded part.

[0048] 7) The hot extruded part obtained in step 6) is subjected to heat treatment, which includes solution treatment and aging treatment. Solution treatment is performed first: solution treatment is performed at 510℃ for 2 hours, followed by quenching in water at 60℃; then aging treatment is performed: aging treatment is performed at 180℃ for 3 hours, followed by air cooling to room temperature to obtain aluminum-based composite material, wherein the aluminum-based composite material is composed of Al-Cu-Mg alloy and silicon carbide particles with a mass fraction of 20% and sericite powder of 2%.

[0049] The aluminum-based composite material obtained in this embodiment is the aluminum-based composite material provided by the present invention, comprising an Al-Cu-Mg alloy matrix and a reinforcing material dispersed in the Al-Cu-Mg alloy matrix. The reinforcing material consists of a silicon carbide particle core and sericite powder encapsulating the silicon carbide particle core. Subsequent embodiments are the same and will not be described again.

[0050] Example 2

[0051] The method for preparing the aluminum-based composite material in this embodiment includes the following steps:

[0052] 1) Silicon carbide particles (particle size 12μm) were acid-washed with an 8% (v / v) hydrofluoric acid solution, then washed with distilled water, filtered, and dried in a vacuum drying oven to obtain cleaned silicon carbide particles; sericite powder (particle size 4μm) was then washed twice with deionized water, and deionized water was added to the cleaned mica powder for ultrasonic cleaning, and the cleaned silicon carbide particles were added at a mass ratio of 10:1, and ultrasonic treatment was continued for 0.5h, filtered, and dried in a vacuum drying oven to obtain a mixed powder A of sericite powder and silicon carbide particles;

[0053] 2) Use agate balls as grinding balls to ball mill the mixed powder A obtained in step 1). Add ethanol as a dispersant to the mixed powder A of sericite powder and silicon carbide particles and ball mill for 23 hours. During ball milling, rotate forward and backward every 0.6 hours. After ball milling, dry in a vacuum drying oven for 15 hours to remove the dispersant, and then dry mill at high energy for 5 hours to form silicon carbide particles with mica powder on the surface.

[0054] 3) The Al-Cu-Mg alloy powder is composed of Al and Cu with a mass fraction of 3.5% and Mg of 1.5%. The Al-Cu-Mg alloy powder is ball-milled for 24 hours to form flake Al-Cu-Mg alloy powder. The flake Al-Cu-Mg alloy powder and the silicon carbide particles with mica powder coating on the surface from step 2) are then wet-milled at a ball milling speed of 200 r / min for 14 hours to obtain a mixed powder B of flake Al-Cu-Mg alloy powder and silicon carbide particles with mica powder coating on the surface.

[0055] 4) The mixed powder B obtained in step 3) is cold-pressed into a preform. The cold pressing of the preform includes segmented pressurization and segmented depressurization. The first segment is pressurized to 140MPa and held for 20s. The second segment is increased to the maximum pressure of 280MPa and held for 20s. When depressurizing, the pressure is first reduced to 150MPa and held for 18s. Then the pressure is completely released to obtain the preform of aluminum-based composite material.

[0056] 5) The preform obtained in step 4) is vacuum sintered in a vacuum annealing furnace at a heating rate of 2℃ / min. It is held at 150℃, 300℃ and 450℃ for 30 min respectively, and then raised to the maximum sintering temperature of 555℃ and held for 5 h. It is then cooled with the furnace to obtain the sintered preform of aluminum-based composite material.

[0057] 6) The sintered blank obtained in step 5) is hot extruded. Before extrusion, it is kept at 490℃ for 2 hours. The extrusion speed is 1.5 mm / s and the extrusion ratio is 20:1 to obtain a densified hot extruded part.

[0058] 7) The hot extruded part obtained in step 6) is subjected to heat treatment, which includes solution treatment and aging treatment. Solution treatment is performed first: solution treatment is performed at 505℃ for 2 hours, followed by quenching in water at 60℃; then aging treatment is performed: aging treatment is performed at 185℃ for 4 hours, followed by air cooling to room temperature to obtain aluminum-based composite material, wherein the aluminum-based composite material is composed of Al-Cu-Mg alloy and silicon carbide particles with a mass fraction of 30% and sericite powder of 3%.

[0059] Example 3

[0060] The method for preparing the aluminum-based composite material in this embodiment includes the following steps:

[0061] 1) Silicon carbide particles (15 μm in diameter) were acid-washed with a 10% (v / v) hydrofluoric acid solution, then washed with distilled water, filtered, and dried in a vacuum drying oven to obtain cleaned silicon carbide particles; sericite powder (3 μm in diameter) was then washed twice with deionized water, and deionized water was added to the cleaned mica powder for ultrasonic cleaning, and the cleaned silicon carbide particles were added at a mass ratio of 8.75:1, and ultrasonic treatment was continued for 0.5 h, filtered, and dried in a vacuum drying oven to obtain a mixed powder A of sericite powder and silicon carbide particles;

[0062] 2) Use agate balls as grinding balls to ball mill the mixed powder A obtained in step 1). Add ethanol as a dispersant to the mixed powder A of sericite powder and silicon carbide particles and ball mill for 24 hours. During ball milling, rotate forward and backward every 1 hour. After ball milling, dry in a vacuum drying oven for 15 hours to remove the dispersant, and then dry mill at high energy for 5 hours to form silicon carbide particles with mica powder on the surface.

[0063] 3) The Al-Cu-Mg alloy powder is composed of Al and Cu with a mass fraction of 3.5% and Mg of 1.5%. The Al-Cu-Mg alloy powder is ball-milled for 24 hours to form flake Al-Cu-Mg alloy powder. The flake Al-Cu-Mg alloy powder and the silicon carbide particles with mica powder coating on the surface from step 2) are then wet-milled at a ball milling speed of 220 r / min for 14 hours to obtain a mixed powder B of flake Al-Cu-Mg alloy powder and silicon carbide particles with mica coating on the surface.

[0064] 4) The mixed powder B obtained in step 3) is cold-pressed into a preform. The cold pressing of the preform includes segmented pressurization and segmented depressurization. The first segment is pressurized to 150MPa and held for 20s. The second segment is increased to the maximum pressure of 270MPa and held for 18s. When depressurizing, the pressure is first reduced to 140MPa and held for 18s. Then the pressure is completely released to obtain the preform of aluminum-based composite material.

[0065] 5) The preform obtained in step 4) is vacuum sintered in a vacuum annealing furnace at a heating rate of 3℃ / min. It is held at 150℃, 300℃ and 450℃ for 30 min respectively, and then raised to the maximum sintering temperature of 560℃ for 5 h. It is then cooled in the furnace to obtain the sintered preform of aluminum-based composite material.

[0066] 6) The sintered billet obtained in step 5) is hot extruded. Before extrusion, it is kept at 485℃ for 3 hours. The extrusion speed is 1.5 mm / s and the extrusion ratio is 20:1 to obtain a densified hot extruded part.

[0067] 7) The hot extruded part obtained in step 6) is subjected to heat treatment, which includes solution treatment and aging treatment. Solution treatment is performed first: solution treatment is performed at 500℃ for 3 hours, followed by quenching in water at 60℃; then aging treatment is performed: aging treatment is performed at 185℃ for 5 hours, followed by air cooling to room temperature to obtain aluminum-based composite material, wherein the aluminum-based composite material is composed of Al-Cu-Mg alloy and silicon carbide particles with a mass fraction of 35% and sericite powder with a mass fraction of 4%.

[0068] Example 4

[0069] 1) Silicon carbide particles (10 μm in diameter) were acid-washed with a 5% (v / v) hydrofluoric acid solution, then washed with distilled water, filtered, and dried in a vacuum drying oven to obtain cleaned silicon carbide particles; sericite powder (3 μm in diameter) was washed twice with deionized water, deionized water was added to the cleaned mica powder for ultrasonic cleaning, and the cleaned silicon carbide particles were added at a mass ratio of 10:1. Ultrasonic treatment was continued for 0.5 h, filtered, and dried in a vacuum drying oven to obtain a mixed powder A of sericite powder and silicon carbide particles;

[0070] 2) Use agate balls as grinding balls to ball mill the mixed powder A obtained in step 1). Add ethanol as a dispersant to the mixed powder A of sericite powder and silicon carbide particles and ball mill for 22 hours. During ball milling, rotate forward and backward every 0.5 hours. After ball milling, dry in a vacuum drying oven for 13 hours to remove the dispersant, and then dry mill at high energy for 4 hours to form silicon carbide particles with sericite powder on the surface.

[0071] 3) The Al-Cu-Mg alloy powder is composed of Al and Cu with a mass fraction of 3.5% and Mg of 1.5%. The Al-Cu-Mg alloy powder is ball-milled for 20 hours to form flake Al-Cu-Mg alloy powder. The flake Al-Cu-Mg alloy powder and the silicon carbide particles with mica powder coating on the surface from step 2) are then wet-milled at a ball milling speed of 180-250 r / min for 12 hours to obtain a mixed powder B of flake Al-Cu-Mg alloy powder and silicon carbide particles with mica powder coating on the surface.

[0072] 4) The mixed powder B obtained in step 3) is subjected to vacuum hot pressing sintering with a vacuum degree of 0.3 Pa. First, a pressure of 70 MPa is applied to the mixed powder, and the temperature is raised to 450°C at a heating rate of 3°C / min and held for 60 min. Then, the temperature is raised to 550°C and the pressure is increased to 130 MPa. The pressure and temperature are held for 4 h. After depressurization, the powder is cooled to room temperature in the furnace to obtain the aluminum-based composite material sintered blank.

[0073] 5) The composite material sintered blank obtained in step 4) is subjected to heat treatment, which includes solution treatment and aging treatment. Solution treatment is performed first: solution treatment is performed at 505℃ for 2 hours, followed by quenching in water at 60℃; then aging treatment is performed: aging treatment is performed at 180℃ for 3 hours, followed by air cooling to room temperature to obtain aluminum-based composite material, wherein the aluminum-based composite material is composed of Al-Cu-Mg alloy and silicon carbide particles with a mass fraction of 25% and sericite powder with a mass fraction of 2.5%.

[0074] II. Experimental Examples

[0075] Experimental Example 1

[0076] This experimental example demonstrates high-magnification transmission electron microscopy (TEM) testing of the aluminum-based composite material from Example 1. The test results are as follows: Figure 1 As shown. From Figure 1 It can be seen that layered mica is wrapped around the surface of silicon carbide particles and dispersed in the aluminum alloy matrix.

[0077] Experiment Example 2

[0078] In this experiment, the tensile strength, elongation and coefficient of thermal expansion of the aluminum-based composite materials obtained in Examples 1 to 3 were tested. The tensile strength test was carried out in accordance with the GBT228-2002 standard, the elongation test was carried out in accordance with the GBT228-2002 standard, and the coefficient of thermal expansion test was carried out in accordance with the GB4339-84 standard. The test results are shown in Table 1.

[0079] Table 1 Tensile strength and elongation of aluminum-based composite materials

[0080]

[0081] As shown in Table 1, the aluminum-based composite materials prepared in Examples 1-4 have high mechanical properties, with tensile strength exceeding 480 MPa and elongation exceeding 8%. This indicates that the aluminum-based composite materials provided by the present invention have strong interfacial bonding, excellent mechanical properties, good strength and toughness, and maintain a good low coefficient of thermal expansion, making them widely applicable in fields such as transportation, precision instruments, aviation, and aerospace.

Claims

1. An aluminum-based composite material, characterized in that, The material comprises an aluminum alloy matrix and a reinforcing material dispersed in the aluminum alloy matrix. The reinforcing material consists of a silicon carbide particle core and a sericite layer surrounding the silicon carbide particle core. The aluminum alloy is an Al-Cu-Mg alloy, comprising 3.5-4.5% Cu and 1.5-2% Mg by mass. The mass ratio of silicon carbide to sericite is 8-10:

1. The total mass of silicon carbide and sericite is 10%-40% of the aluminum-based composite material.

2. The aluminum-based composite material as described in claim 1, characterized in that, The silicon carbide particles have a particle size of 10-15 μm, and the sericite layer is formed of sheet-like sericite with a sheet diameter of 3-5 μm.

3. A method for preparing the aluminum-based composite material as described in claim 1, characterized in that, Includes the following steps: 1) The mixture of silicon carbide particles and sericite powder is ball-milled to obtain silicon carbide particles coated with sericite powder; 2) The silicon carbide particles coated with sericite powder and flake aluminum alloy powder are ball-milled and mixed evenly, and then pressed and sintered to obtain an aluminum-based composite material; the ball milling in step 1) includes wet ball milling and high-energy dry ball milling.

4. The method for preparing the aluminum-based composite material as described in claim 3, characterized in that, The wet ball milling time is 20-24 hours, and the high-energy dry ball milling time is 4-6 hours.

5. The method for preparing the aluminum-based composite material as described in claim 3, characterized in that, The sintering in step 2) is high-temperature sintering or hot-pressing sintering. The high-temperature sintering includes four-stage high-temperature sintering, which includes heat preservation treatment at 120~180℃, 280~320℃, 430~480℃ and 540~560℃ respectively.

6. The method for preparing the aluminum-based composite material as described in claim 5, characterized in that, The four-stage high-temperature sintering involves holding at 120–180℃, 280–320℃, and 430–480℃ for 15–45 minutes, and then holding at 540–560℃ for 3–6 hours.

7. The method for preparing the aluminum-based composite material as described in claim 5, characterized in that, The hot pressing sintering is vacuum hot pressing sintering with a vacuum degree of 0.2-0.4 Pa. The specific method of hot pressing sintering is as follows: under vacuum conditions, a pressure of 50-90 MPa is applied to the mixed powder, and the temperature is raised to 430-470℃ at a heating rate of 2-4℃ / min and held at the pressure for 50-70 min; then the pressure is increased to 120-150 MPa, and the temperature is continued to rise to 530-570℃ and held at the pressure for 3-5 h. After depressurization, the powder is cooled to room temperature in the furnace.

8. The method for preparing the aluminum-based composite material as described in claim 5, characterized in that, After high-temperature sintering, hot deformation densification and heat treatment are carried out. The hot deformation densification is hot extrusion. The hot extrusion is carried out after holding at 470~490℃ for 2~3 hours. The extrusion ratio of the hot extrusion is 15~25:

1.

9. The method for preparing the aluminum-based composite material as described in claim 8, characterized in that, The hot extrusion rate is 1 to 2 mm / s.

10. The method for preparing the aluminum-based composite material as described in claim 8, characterized in that, The heat treatment includes solution treatment and aging treatment. The solution treatment is to hold at 500~510℃ for 2~4 hours, and the aging treatment is to age at 175~180℃ for 3~12 hours.

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