High-temperature-resistant high-strength aluminum matrix composite material and preparation method thereof

Abstract

The application relates to a high-temperature-resistant high-strength aluminum-based composite material and a preparation method thereof, and belongs to the technical field of metal-based composite material processing. The nanometer reinforcing body powder is subjected to ultrasonic pretreatment; long-time ball milling is adopted to prepare composite powder with small size; a process control agent is added in batches in the ball milling process to prevent the caking or excessive cold welding phenomenon in the ball milling process. In the hot-pressing sintering process, a transient liquid-phase sintering process is adopted, and a hot extrusion densification treatment is carried out in subsequent secondary processing. Finally, a nanometer precipitation strengthening phase is formed in the aluminum-based composite material through heat treatment, effectively preventing the crystal lattice slip and dislocation movement, preventing the grain growth and grain boundary migration under high-temperature conditions, and improving the thermal stability and high-temperature resistance of the material. The high-temperature-resistant high-strength aluminum-based composite material prepared by the application has high room-temperature and high-temperature mechanical properties, and has a wide application prospect in the industrial fields of aerospace, national defense industry and transportation.

Description

Technical Field

[0001] This invention belongs to the field of metal matrix composite material processing technology, and mainly relates to a high-temperature resistant and high-strength aluminum matrix composite material and its preparation method. Background Technology

[0002] In recent years, aluminum alloys have been widely used as structural materials in aerospace, defense, and transportation industries due to their low density, high thermal conductivity, high specific strength, and excellent wear resistance. They are particularly important for maintaining stable mechanical properties under certain high-temperature environments (such as aircraft engine pistons, fan exhaust guide vanes, and aerospace engine structural components). Currently, although aluminum alloys based on the Al-Zn-Mg, Al-Cu-Mg, or Al-Li series exhibit high strength at room temperature, their high-temperature strength decreases significantly due to grain coarsening and diffusion of alloying elements. Common precipitates such as Mg2Si, CuAl2, and MgZn2 rapidly coarsen or dissolve above 200℃, losing their strengthening effect. Therefore, improving the mechanical properties and thermal stability of aluminum alloys and related materials at high temperatures is crucial.

[0003] To prepare high-strength, heat-resistant alloys, researchers have introduced transition metals (TMs) with low diffusion coefficients, such as Cr, Fe, Ti, and Zr, into aluminum alloys to obtain a large number of dispersed phases with excellent thermal stability, which pin dislocations and grain boundaries at high temperatures. However, the formation of hard and brittle intermetallic compound phases reduces the alloy's plasticity, deformability, and strength, significantly limiting the content of transition metals and restricting the widespread application of this method. Compared with adding TMs, aluminum matrix composites (AMCs) prepared by adding ceramic particle reinforcing phases exhibit higher thermal stability and lower coefficients of thermal expansion. At high temperatures, the aluminum matrix undergoes dynamic recovery recrystallization, resulting in weak strength. Adding reinforcing phases with better high-temperature performance allows for load transfer from the matrix to the reinforcing phase through the interface, thereby improving the high-temperature performance of the composite material. In particular, the simple preparation process and low cost of AMCs have attracted considerable attention as candidate materials for high-temperature applications.

[0004] In the early stages, due to limitations in technology and processes, micron-sized ceramic particles were mostly used as reinforcing phases. Nanoparticles have only recently gained widespread attention because they can maintain or even improve the plasticity of composite materials while increasing strength. Commonly used nanoparticles for aluminum matrix composites include Al2O3, SiC, B4C, and TiB2. Among them, Al2O3, due to its stable chemical properties, high thermal conductivity, low coefficient of thermal expansion, and good wear resistance, has been reported as a promising high-temperature mechanical property reinforcing material, capable of significantly improving the performance of composite materials. However, agglomeration is prone to occur during the preparation of nanoparticle-reinforced aluminum matrix composites, and this agglomeration is one of the key issues affecting the room temperature and high-temperature mechanical properties of the composites. Furthermore, due to the large surface energy of nanoparticles, clumping or excessive cold welding can easily occur during prolonged ball milling, also affecting the final material's performance. Because the interfacial bonding between ceramic reinforcing phase particles and the matrix is ​​relatively weak, the interfacial bonding strength further decreases with increasing temperature, affecting interfacial load transfer and leading to a reduction in the high-temperature mechanical properties of the composite material. In addition, given a fixed volume fraction of nano-reinforcing phase, controlling the microstructure of aluminum matrix composites through heat treatment to precipitate thermally stable nano-reinforcing phases and effectively suppress dislocation slip during tensile loading is also an effective means to improve the high-temperature mechanical properties of composite materials.

[0005] Therefore, improving the agglomeration problem of nanoparticle reinforcements and their interfacial bonding conditions with the matrix, solving the problems of agglomeration or excessive cold welding during long-term ball milling, and the small volume fraction and uneven distribution of thermally stable nano-precipitated reinforcing phases have become key technologies that urgently need to be overcome in the preparation of high-temperature and high-strength aluminum matrix composites. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a high-temperature resistant, high-strength aluminum-based composite material and its preparation method. In this invention, the nano-reinforcement powder is first pretreated. Ultrasonic treatment disperses the nano-reinforcement powder uniformly, preventing agglomeration and improving its dispersibility. The aluminum-based composite powder is prepared using a long-term ball milling method. Due to the prolonged high-energy ball milling, the nano-reinforcement particles are uniformly distributed in the composite powder, and the small particle size provides favorable conditions for the formation of fine grains during subsequent sintering. During the long-term ball milling process, process control agents are added in batches to effectively prevent agglomeration or excessive cold welding, significantly improving the powder yield. During the hot-pressing sintering process... Using transient liquid phase sintering and subsequent hot extrusion densification in secondary processing helps increase the wettability between the matrix and the reinforcement, ensuring effective bonding between them, increasing the relative density of the composite material, avoiding weak areas between the matrix and the reinforcement, and ensuring uniform interfacial load transfer at high temperatures. Finally, the formation of nano-precipitated strengthening phases in the aluminum matrix composite material through heat treatment can effectively prevent lattice slip and dislocation movement. At high temperatures, the nano-precipitated strengthening phases can prevent grain growth and grain boundary migration, thereby maintaining the strength and structural stability of the material and improving its thermal stability and high-temperature resistance.

[0007] Therefore, the aluminum-based composite material prepared by this invention has a fine grain structure, uniform distribution of nano-reinforcing particles, and a good bonding interface with the matrix. It also exhibits a high-density, uniformly distributed nanoscale precipitated reinforcing phase, resulting in excellent mechanical properties such as hardness, tensile strength, and elongation. The prepared aluminum-based composite material achieves a tensile strength of 617 MPa and an elongation of 7.7% at room temperature. At high temperatures (200℃, 300℃, and 400℃), the tensile strengths reach 446 MPa, 311 MPa, and 201 MPa, respectively, with elongations of 9.9%, 10.6%, and 6.1%. Compared to traditional aluminum-based composite materials, its high-temperature mechanical properties are significantly improved, enabling it to operate well in the 200℃-400℃ high-temperature range. It has broad application prospects in aerospace, defense, and transportation industries.

[0008] The present invention provides the following solution: A high-temperature resistant, high-strength aluminum-based composite material and its preparation method, characterized by comprising the following steps:

[0009] (1) The nano-reinforced powder was pretreated and ultrasonically vibrated in ethanol at a frequency of 80 kHz for 30 minutes and then dried in a drying oven at 100 ℃ for 3 hours.

[0010] (2) The nano-reinforcement powder obtained in step (1) is mixed with aluminum alloy powder in a certain proportion to obtain a mixed powder.

[0011] (3) The mixed powder obtained in step (2) is subjected to high-energy ball milling for 40-55 hours to obtain aluminum-based composite powder with uniformly dispersed reinforcement.

[0012] (4) The aluminum-based composite powder obtained in step (3) is sieved and then pre-pressed. The pre-pressed green blank is obtained by using a press.

[0013] (5) The pre-pressed green billet obtained in step (4) is subjected to transient liquid phase sintering to obtain sintered billet;

[0014] (6) Heat and keep warm the sintered billet and extrusion die obtained in step (5) respectively, and then place the sintered billet into the extrusion die to extrude and prepare aluminum-based composite material.

[0015] (7) The aluminum-based composite material obtained in step (6) is subjected to solution treatment at a temperature of 510℃-550℃ for 30min-90min. Then, the composite material is rapidly quenched in quenching oil at 50-80℃ and held for 1-10min. Finally, artificial aging treatment is performed at a temperature of 160℃-200℃ for 7h-9h. After that, it is cooled to room temperature in the furnace to obtain the high-temperature resistant and high-strength aluminum-based composite material.

[0016] Further, the nano-reinforcing powder mentioned in steps (1) and (2) is nano-Al2O3 powder with a particle size range of 10-50 nm; the aluminum alloy powder is 6061 aluminum alloy powder with a particle size range of 20-50 μm.

[0017] Furthermore, in step (2), the volume ratio of nano-Al2O3 powder to aluminum alloy powder is 1:9-39;

[0018] Further, during the long-term ball milling process described in step (3), the ball milling speed is 200-300 r / min, and the cooling is paused for 5 minutes after every 15 minutes of ball milling; during the long-term ball milling process, 0.2wt%-0.5wt% of process control agent is added every 5 hours of ball milling, and the total amount of process control agent added should account for 2%-5.5% of the total mass of the mixed powder; the process control agent is stearic acid;

[0019] Furthermore, in the long-term ball milling process described in step (3), the grinding media is stainless steel grinding balls, the mass ratio of mixed powder to grinding balls is 1:5-20, and the diameter of stainless steel grinding balls is 5mm, 8mm and 10mm, with a mass ratio of 5:3:2.

[0020] Furthermore, the pre-compression molding pressure in step (4) is 20 MPa, and the pre-compression time is 10 min;

[0021] Further, the transient liquid phase sintering process described in step (5) is as follows: First, the temperature is raised to 380-450℃ and held for 20 min at a rate of 10℃ / min, while a constant pressure of 20-50 MPa is applied to the sample. Then, the temperature is raised to 680℃ at a rate of 10℃ / min, held for 3 min, and then rapidly cooled to 580℃ and held for 60-120 min. After the holding time is completed, the constant pressure is removed, and the sample is cooled to room temperature with the furnace. The vacuum degree inside the furnace during the sintering process is ≤10 Pa.

[0022] Furthermore, the pretreatment, batching, ball milling, and sieving described in steps (1), (2), and (3) are all carried out in a vacuum environment or an inert gas environment;

[0023] Further, in step (6), the sintered billet and the extrusion die are kept at a temperature of 450℃-470℃ for 20 minutes; after the sintered billet is placed into the extrusion die, it is hot extruded, the extruder temperature is 400℃-450℃, the extrusion ratio is 12:1, and the extrusion speed is 4.6mm / s; the inlet and outlet of the extrusion die in step (6) are rod-shaped.

[0024] The beneficial effects of this invention are:

[0025] In this invention, the nano-reinforcement powder is first pretreated. Ultrasonic treatment disperses the nano-reinforcement powder evenly, preventing agglomeration and improving its dispersibility. Aluminum-based composite powder is prepared using a 40-55 hour long-time ball milling method. Due to the prolonged high-energy ball milling, the nano-reinforcement particles are evenly distributed in the composite powder, and the fine particle size provides favorable conditions for the formation of fine grains during subsequent sintering. Adding process control agents in batches during the long-time ball milling process effectively prevents agglomeration or excessive cold welding, significantly improving the powder yield. During hot pressing sintering… The transient liquid phase sintering process and subsequent hot extrusion densification in the secondary processing help increase the wettability between the matrix and the reinforcement, ensure effective bonding between the matrix and the reinforcement, increase the relative density of the composite material, avoid weak areas between the matrix and the reinforcement, and ensure uniform interfacial load transfer at high temperatures. Finally, the formation of nano-precipitated strengthening phases in the aluminum matrix composite material through heat treatment can effectively prevent lattice slip and dislocation movement. Under high temperature conditions, the nano-precipitated strengthening phases can prevent grain growth and grain boundary migration, thereby maintaining the strength and structural stability of the material and improving its thermal stability and high temperature resistance.

[0026] The aluminum-based composite material prepared by this invention has a fine grain structure, uniform distribution of nano-reinforcing particles, and a good bonding interface with the matrix. It also exhibits a high-density, uniformly distributed nanoscale precipitated reinforcing phase, resulting in excellent mechanical properties such as hardness, tensile strength, and elongation. The prepared aluminum-based composite material achieves a tensile strength of 617 MPa and an elongation of 7.7% at room temperature. At high temperatures (200℃, 300℃, and 400℃), the tensile strengths reach 446 MPa, 311 MPa, and 201 MPa, respectively, with elongations of 9.9%, 10.6%, and 6.1%. Compared to traditional aluminum-based composite materials, its high-temperature mechanical properties are significantly improved, enabling it to operate well in the 200℃-400℃ high-temperature range. It has broad application prospects in aerospace, defense, and transportation industries. Attached Figure Description

[0027] Figure 1 Metallographic image of the high-temperature resistant and high-strength aluminum-based composite material prepared in Example 1.

[0028] Figure 2 The image shows a TEM image of the high-temperature resistant and high-strength aluminum-based composite material prepared in Example 1.

[0029] Figure 3 The tensile stress-strain curves of the high-temperature resistant and high-strength aluminum-based composite material prepared in Example 1 under room temperature / high temperature conditions. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0031] Example 1:

[0032] A high-temperature resistant, high-strength aluminum-based composite material and its preparation method are as follows:

[0033] (1) The nano Al2O3 powder with an average particle size of 13 nm was pretreated, and then ultrasonically oscillated in ethanol at a frequency of 80 kHz for 30 minutes and then dried in a drying oven at 100 ℃ for 3 hours.

[0034] (2) The nano Al2O3 reinforcing powder obtained in step (1) is mixed with 6061 aluminum alloy powder with an average particle size of 30 μm at a volume ratio of 1:19 to obtain a mixed powder.

[0035] (3) The mixed powder obtained in step (2) is subjected to high-energy ball milling for 50 hours. The ball milling speed is 200 r / min. After each ball milling for 15 minutes, the cooling is paused for 5 minutes. After each ball milling for 5 hours, 0.5% process control agent is added. The total amount of process control agent stearic acid added accounts for 5% of the total mass of the mixed powder. During the long-term ball milling, the ball milling media is stainless steel grinding balls. The mass ratio of mixed powder to grinding balls is 1:10. The diameters of the stainless steel grinding balls are 5 mm, 8 mm and 10 mm, and the mass ratio is 5:3:2 to obtain aluminum-based composite powder with uniformly dispersed reinforcement. The pretreatment, batching and ball milling in steps (1), (2) and (3) are all carried out in a vacuum environment or an inert gas environment.

[0036] (4) The aluminum-based composite powder obtained in step (3) is sieved and then pre-pressed. The pre-pressed material is formed by using a press with a pressure of 20 MPa and a pre-pressing time of 10 min to obtain the pre-pressed green blank.

[0037] (5) The pre-pressed green blank obtained in step (4) is subjected to transient liquid phase sintering. The sintering process is as follows: First, the temperature is raised to 400℃ and held for 20 min at a rate of 10℃ / min, while a constant pressure of 40MPa is applied to the sample. Then, the temperature is raised to 680℃ at a rate of 10℃ / min and held for 3 min. After that, the temperature is rapidly lowered to 580℃ and held for 60 min. After the holding time is over, the constant pressure is removed and the sample is cooled to room temperature with the furnace. The vacuum degree in the furnace during the sintering process is ≤10Pa, and the sintered green blank is obtained.

[0038] (6) The sintered billet and the extrusion die obtained in step (5) are heated and kept at a temperature of 460°C for 20 minutes. The sintered billet is placed into the extrusion die and then hot extruded (the inlet and outlet of the extrusion die are rod-shaped). The extruder temperature is 440°C, the extrusion ratio is 12:1, and the extrusion speed is 4.6 mm / s to obtain aluminum-based composite material.

[0039] (7) The aluminum-based composite material obtained in step (6) is subjected to solution treatment at a temperature of 530°C for 60 min. Then, the composite material is rapidly quenched in quenching oil at 60°C and held for 5 min. Finally, artificial aging treatment is performed at a temperature of 180°C for 8 h. After that, it is cooled to room temperature in the furnace to obtain the high-temperature resistant and high-strength aluminum-based composite material.

[0040] The prepared high-temperature resistant and high-strength aluminum-based composite material has high density and no obvious pores, such as Figure 1As shown in the metallographic diagram, the aluminum alloy matrix is ​​white, the gray area represents uniformly dispersed nano-reinforcing particles, and the black area represents the precipitated strengthening phase Mg2Si. The matrix has a fine grain structure, the nano-reinforcing particles are uniformly distributed, and they have a good bonding interface with the matrix structure. Simultaneously, a high-density, uniformly distributed nano-scale precipitated strengthening phase is obtained, such as... Figure 2 As shown in the TEM image, the Vickers hardness of this composite material is 142 HV. The mechanical properties, including room temperature and high temperature tensile strength and elongation, are shown in Table 1, and the corresponding stress-strain curves are as follows. Figure 3 As shown.

[0041] (The Vickers hardness measured in this invention was tested according to the national standard test method GB-T4340.1-2009, the room temperature tensile test method was tested according to the national standard test method GB / T 228.1-2021, and the high temperature tensile test method was tested according to the national standard test method GB / T228.2-2015.)

[0042] Table 1 Mechanical properties of aluminum-based composite materials in Example 1 at different temperatures

[0043] room temperature 617 7.7 200℃ 446 9.9 300℃ 311 10.6 400℃ 201 4.9

[0044] Example 2:

[0045] A high-temperature resistant, high-strength aluminum-based composite material and its preparation method are as follows:

[0046] (1) The nano Al2O3 powder with an average particle size of 30 nm was pretreated, and then ultrasonically oscillated in ethanol at a frequency of 80 kHz for 30 minutes and then dried in a drying oven at 100 ℃ for 3 hours.

[0047] (2) The nano Al2O3 reinforcing powder obtained in step (1) is mixed with 6061 aluminum alloy powder with an average particle size of 45 μm at a volume ratio of 1:32 to obtain a mixed powder.

[0048] (3) The mixed powder obtained in step (2) was subjected to high-energy ball milling for 45 hours at a speed of 250 r / min. After each 15-minute ball milling, the powder was paused for 5 minutes to cool. After each 5-hour ball milling, 0.3% of process control agent was added. The total amount of stearic acid added as process control agent accounted for 2.7% of the total mass of the mixed powder. During the long-term ball milling, the grinding media was stainless steel grinding balls. The mass ratio of the mixed powder to the grinding balls was 1:15. The diameters of the stainless steel grinding balls were 5 mm, 8 mm, and 10 mm, with a mass ratio of 5:3:2, to obtain aluminum-based composite powder with uniformly dispersed reinforcement. The pretreatment, batching, and ball milling described in steps (1), (2), and (3) were all carried out in a vacuum environment or an inert gas environment.

[0049] (4) The aluminum-based composite powder obtained in step (3) is sieved and then pre-pressed. The pre-pressed material is formed by using a press with a pressure of 20 MPa and a pre-pressing time of 10 min to obtain the pre-pressed green blank.

[0050] (5) The pre-pressed green blank obtained in step (4) is subjected to transient liquid phase sintering. The sintering process is as follows: First, the temperature is raised to 380℃ and held for 20 min at a rate of 10℃ / min, while a constant pressure of 30MPa is applied to the sample. Then, the temperature is raised to 680℃ at a rate of 10℃ / min and held for 3 min. After that, the temperature is rapidly lowered to 580℃ and held for 90 min. After the holding time is over, the constant pressure is removed and the sample is cooled to room temperature with the furnace. The vacuum degree in the furnace during the sintering process is ≤10Pa, and the sintered green blank is obtained.

[0051] (6) The sintered billet and the extrusion die obtained in step (5) are heated and kept at a temperature of 450°C for 20 minutes. The sintered billet is placed into the extrusion die and then hot extruded (the inlet and outlet of the extrusion die are rod-shaped). The extruder temperature is 420°C, the extrusion ratio is 12:1, and the extrusion speed is 4.6 mm / s to prepare aluminum-based composite material.

[0052] (7) The aluminum-based composite material obtained in step (6) was subjected to solution treatment at a temperature of 550℃ for 30 minutes. Then, the composite material was rapidly quenched in quenching oil at 50℃ and held for 2 minutes. Finally, artificial aging treatment was performed at a temperature of 160℃ for 9 hours. Afterward, it was cooled to room temperature in the furnace to obtain a high-temperature resistant and high-strength aluminum-based composite material. The hardness of the composite material is 125HV. The mechanical properties such as room temperature and high temperature tensile strength and elongation are shown in Table 2.

[0053] Table 2 Mechanical properties of aluminum-based composite materials in Example 2 at different temperatures

[0054] room temperature 568 9.1 200℃ 370 13.6 300℃ 256 16.3 400℃ 174 10.3

[0055] Comparative Example 1:

[0056] A method for preparing an aluminum-based composite material, the difference between Comparative Example 1 and Example 1 is that: in step (3), the mixed powder is subjected to high-energy ball milling for 20 hours at a ball milling speed of 200 r / min, with a 5-minute pause for cooling after every 15 minutes of ball milling, and 0.5% process control agent is added every 5 hours of ball milling, with the total amount of process control agent added accounting for 2% of the total mass of the mixed powder. The rest is the same as in Example 1. The room temperature and high temperature tensile strength, elongation and other mechanical properties of the aluminum-based composite material prepared in Comparative Example 1 are shown in Table 3.

[0057] As shown in Tables 1 and 3, the aluminum-based composite material exhibits higher room-temperature and high-temperature tensile strengths when subjected to 50 hours of high-energy ball milling compared to 20 hours. Since nano-Al2O3 particles primarily enter the aluminum alloy matrix through the cold welding and crushing process during high-energy ball milling, shorter milling times lead to their aggregation mainly on the surface of the aluminum alloy particles. This aggregation results in weakened reinforcing effects after sintering. Furthermore, prolonged high-energy ball milling reduces the matrix grain size, which also contributes to improved mechanical properties through the Hall-Petch effect; finer grains exhibit stronger inhibition of dislocation movement at grain boundaries. Additionally, short-time ball milling causes the formation of aggregated regions of nano-Al2O3 particles, which are difficult to densify and tend to create porosity in the sintered composite material. Therefore, a suitable prolonged high-energy ball milling process ensures uniform distribution of nanoparticle reinforcement in the composite powder, significantly improving the mechanical properties of the aluminum-based composite material.

[0058] Table 3 Comparative Example 1 Mechanical properties of aluminum-based composite materials at different temperatures

[0059] room temperature 332 18.5 200℃ 260 22.3 300℃ 161 26.9 400℃ 79 35.3

[0060] Comparative Example 2:

[0061] A method for preparing an aluminum-based composite material, the difference between Comparative Example 2 and Example 1 is as follows: In step (5), the pre-pressed green blank is hot-pressed and sintered. First, the temperature is raised to 400℃ and held for 20 min at a heating rate of 10℃ / min, while a constant pressure of 40MPa is applied to the sample. Then, the temperature is raised to 580℃ at a rate of 10℃ / min and held for 60 min. After the holding time, the constant pressure is removed, and the sample is cooled to room temperature with the furnace. During the sintering process, the vacuum degree in the furnace is ≤10Pa, and a sintered blank is obtained. The rest is the same as in Example 1. The room temperature and high temperature tensile strength, elongation, and other mechanical properties of the aluminum-based composite material prepared in Comparative Example 2 are shown in Table 4.

[0062] Table 4 Mechanical properties of aluminum-based composite materials in Comparative Example 2 at different temperatures

[0063]

[0064]

[0065] Comparative Example 3:

[0066] A method for preparing an aluminum-based composite material, the difference between Comparative Example 3 and Example 1 is that: no secondary hot extrusion treatment is performed, and after obtaining the sintered billet in step (5), the solution aging treatment in step (6) is performed directly. The rest is the same as in Example 1. The room temperature and high temperature tensile strength, elongation and other mechanical properties of the aluminum-based composite material prepared in Comparative Example 3 are shown in Table 5.

[0067] As shown in Tables 1 and 4, the composite material prepared by using a suitable transient liquid-phase sintering process during hot-pressing exhibits higher room-temperature and high-temperature mechanical properties compared to the solid-phase sintering composite material in Comparative Example 2. By controlling the temperature and pressure conditions of transient liquid-phase sintering, the grain size and morphology of the material can be precisely controlled to achieve the desired microstructure and properties. In the presence of the liquid phase, the uniform distribution and strengthening effect of nano-reinforcing particles in the composite material can be promoted. Transient liquid-phase sintering can promote the formation of a good bond between the matrix and reinforcing particles at relatively high temperatures for a short period of time, improving the load transfer capacity of the composite material and increasing its density.

[0068] As shown in Tables 1 and 5, the room temperature and high temperature mechanical properties of the composite material are also improved to some extent after hot extrusion densification in the subsequent secondary processing. By controlling the pressure and temperature during the extrusion process, the bonding between material particles becomes tighter, internal defects are reduced, and it helps to eliminate pores and defects inside the material, thereby improving the density and uniformity of the material. At the same time, extrusion deformation makes the particle distribution of the aluminum matrix composite material more uniform, improving the material's processing performance and plasticity, making it easier to perform subsequent processing and forming.

[0069] Table 5 Mechanical properties of aluminum-based composite materials in Comparative Example 3 at different temperatures

[0070]

[0071]

[0072] Comparative Example 4:

[0073] A method for preparing an aluminum-based composite material, the difference between Comparative Example 4 and Example 1 is that: in step (7), the aluminum-based composite material is subjected to solution treatment at a temperature of 480°C for 15 minutes, then the composite material is water-quenched at room temperature, and finally subjected to artificial aging treatment at a temperature of 180°C for 8 hours, after which it is cooled to room temperature in a furnace. The rest is the same as in Example 1.

[0074] Table 6 Mechanical properties of aluminum-based composite materials in Comparative Example 4 at different temperatures

[0075] room temperature 501 10.7 200℃ 366 16.9 300℃ 231 11.4 400℃ 115 5.9

[0076] Comparative Example 5:

[0077] A method for preparing an aluminum-based composite material, the difference between Comparative Example 5 and Example 1 is that: in step (7), the aluminum-based composite material is subjected to solution treatment at a temperature of 580°C for 200 min, and then the composite material is rapidly quenched in quenching oil at 60°C and held for 5 min. Finally, artificial aging treatment is performed at a temperature of 180°C for 8 h, and then the material is cooled to room temperature in the furnace. The rest is the same as in Example 1.

[0078] Table 7 Mechanical properties of aluminum-based composite materials in Comparative Example 5 at different temperatures

[0079] room temperature 489 12.3 200℃ 354 18.1 300℃ 209 15.1 400℃ 109 7.3

[0080] Comparative Example 6:

[0081] A method for preparing an aluminum-based composite material, the difference between Comparative Example 6 and Example 1 is that: in step (7), the aluminum-based composite material is subjected to solution treatment at a temperature of 530°C for 60 min, and then the composite material is rapidly quenched in quenching oil at 60°C and held for 5 min. Finally, artificial aging treatment is performed at a temperature of 100°C for 4 h, followed by furnace cooling to room temperature. The rest is the same as in Example 1.

[0082] Table 8 Mechanical properties of aluminum-based composite materials in Comparative Example 6 at different temperatures

[0083] room temperature 513 10.3 200℃ 412 11.2 300℃ 245 10.8 400℃ 129 5.5

[0084] Comparative Example 7:

[0085] A method for preparing an aluminum-based composite material, the difference between Comparative Example 7 and Example 1 is that: in step (7), the aluminum-based composite material is subjected to solution treatment at a temperature of 530°C for 60 minutes, then the composite material is water-quenched at room temperature, and finally subjected to artificial aging treatment at a temperature of 260°C for 12 hours, after which it is cooled to room temperature in a furnace. The rest is the same as in Example 1.

[0086] As can be seen from Tables 1 and 6-9, Example 1 and Comparative Examples 4, 5, 6, and 7 have a significant impact on the mechanical properties of the composite materials under different heat treatment conditions. Appropriate heat treatment processes can significantly improve the room temperature and high temperature mechanical properties of the aluminum matrix composites. In Comparative Example 4, although the aluminum matrix composite maintained a fine grain structure under lower solution temperatures and shorter treatment times, the insufficient solid solution of the second phase affected the subsequent aging precipitation ability. In Comparative Example 5, higher solution temperatures and longer treatment times increased the concentration of supersaturated solid solution in the matrix aluminum alloy, but this led to recrystallized grain growth and the formation of a coarsened structure, which in turn reduced the mechanical properties. In Comparative Example 6, lower aging temperatures and shorter treatment times resulted in incomplete precipitation of the second phase in the matrix alloy, leading to a weak precipitation strengthening effect. The precipitation strengthening effect increased with the increase of the number of precipitated phases, but in Comparative Example 7, higher aging temperatures and longer treatment times caused the precipitated phases to grow, which also gradually weakened the strengthening effect. As shown in Table 1, the room temperature and high temperature tensile strength of the composite material are improved after appropriate heat treatment, but the improvement is smaller as the tensile test temperature increases.

[0087] Table 9 Mechanical properties of aluminum-based composite materials in Comparative Example 7 at different temperatures

[0088] room temperature 493 11.3 200℃ 344 18.9 300℃ 222 13.9 400℃ 107 7.8

[0089] In summary, the present invention provides a high-temperature resistant, high-strength aluminum-based composite material and its preparation method: Pretreatment of the nano-reinforcement powder, followed by ultrasonication to uniformly disperse the nano-reinforcement powder and prevent agglomeration, thus improving its dispersibility; prolonged high-energy ball milling ensures uniform distribution of the nano-reinforcement particles in the composite powder, resulting in fine particle size; batch addition of process control agents during the long-term ball milling process effectively prevents agglomeration or excessive cold welding, significantly improving powder yield; and the use of transient liquid-phase sintering during hot pressing sintering. Furthermore, the hot extrusion densification process in subsequent secondary processing helps to increase the wettability between the matrix and the reinforcement, ensures effective bonding between the matrix and the reinforcement, increases the relative density of the composite material, avoids weak areas between the matrix and the reinforcement, and ensures uniform interfacial load transfer under high temperature conditions. Finally, the formation of nano-precipitated strengthening phases in the aluminum matrix composite material through heat treatment can effectively prevent lattice slip and dislocation movement. Under high temperature conditions, the nano-precipitated strengthening phases can prevent grain growth and grain boundary migration, thereby maintaining the strength and structural stability of the material and improving its thermal stability and high temperature resistance.

[0090] Therefore, the aluminum-based composite material prepared by this invention has a fine grain structure, uniform distribution of nano-reinforcing particles, and a good bonding interface with the matrix structure. It also exhibits a high-density, uniformly distributed nanoscale precipitated reinforcing phase, resulting in excellent mechanical properties such as hardness, tensile strength, and elongation. Compared to traditional aluminum-based composite materials, its high-temperature mechanical properties are significantly improved, possessing excellent characteristics such as high temperature resistance and high strength.

[0091] The above-described embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above-described embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a high-temperature resistant, high-strength aluminum-based composite material, characterized in that, Specifically, the steps include the following: (1) The nano-reinforced powder was pretreated and then dried after being ultrasonically vibrated in ethanol at a frequency of 80 kHz for 30 minutes. (2) The nano-reinforcement powder obtained in step (1) is mixed with aluminum alloy powder in a certain proportion to obtain a mixed powder; (3) The mixed powder obtained in step (2) is subjected to high-energy ball milling for 40-55 hours to obtain aluminum-based composite powder with uniformly dispersed reinforcement. (4) The aluminum-based composite powder obtained in step (3) is sieved and then pre-pressed. The pre-pressed green blank is obtained by using a press. (5) The pre-pressed green billet obtained in step (4) is subjected to transient liquid phase sintering to obtain sintered billet; (6) Heat and keep warm the sintered billet and extrusion die obtained in step (5) respectively, and then place the sintered billet into the extrusion die to extrude and prepare aluminum-based composite material. (7) The aluminum-based composite material obtained in step (6) is subjected to solution treatment at a temperature of 510℃-550℃ and a time of 30min-90min. Then, the composite material is rapidly quenched in quenching oil at 50-80℃ and held for 1-10min. Finally, it is subjected to artificial aging treatment at a temperature of 160℃-200℃ and a time of 7h-9h. After that, it is cooled to room temperature in the furnace to obtain a high-temperature resistant and high-strength aluminum-based composite material. The nano-reinforcing powder mentioned in steps (1) and (2) is nano-Al2O3 powder with a particle size range of 10-50nm; the aluminum alloy powder is 6061 aluminum alloy powder with a particle size range of 20-50μm; the volume ratio of nano-Al2O3 powder to aluminum alloy powder in step (2) is 1:9-39. In step (3), during the long-term high-energy ball milling process, the ball milling speed is 200-300 r / min, and the cooling is paused for 5 minutes after every 15 minutes of ball milling; during the long-term high-energy ball milling process, 0.2%-0.5% of process control agent is added every 5 hours of ball milling, and the total amount of process control agent added should account for 2%-5.5% of the total mass of the mixed powder; the process control agent is stearic acid; In the long-term high-energy ball milling process described in step (3), the grinding media is stainless steel grinding balls, the mass ratio of mixed powder to grinding balls is 1:10-15, and the diameter of stainless steel grinding balls is 5mm, 8mm and 10mm, with a mass ratio of 5:3:

2. The transient liquid phase sintering process described in step (5) is as follows: First, the temperature is raised to 380-450℃ and held for 20 min at a rate of 10℃ / min, while a constant pressure of 20-50MPa is applied to the sample. Then, the temperature is raised to 680℃ at a rate of 10℃ / min and held for 3 min. After that, the temperature is rapidly lowered to 580℃ and held for 60-120 min. After the holding time is over, the constant pressure is removed and the sample is cooled to room temperature with the furnace. The vacuum degree inside the furnace during the sintering process is ≤10Pa.

2. The method for preparing high-temperature resistant and high-strength aluminum-based composite material according to claim 1, characterized in that, The pre-compression molding pressure in step (4) is 20 MPa, and the pre-compression time is 10 min.

3. The method for preparing the high-temperature resistant and high-strength aluminum-based composite material according to claim 1, characterized in that, The pretreatment, batching, ball milling, and sieving described in steps (1), (2), and (3) are all carried out in a vacuum environment or an inert gas environment.

4. The method for preparing high-temperature resistant and high-strength aluminum-based composite material according to claim 1, characterized in that, The sintered billet and extrusion die in step (6) are kept at a temperature of 450℃-470℃ for 20 minutes. After the sintered billet is placed into the extrusion die, it is hot extruded. The extruder temperature is 400℃-450℃, the extrusion ratio is 12:1, and the extrusion speed is 4.6mm / s. The inlet and outlet of the extrusion die in step (6) are rod-shaped.

5. A high-temperature resistant and high-strength aluminum-based composite material is prepared according to any one of claims 1-4.

6. The high-temperature resistant and high-strength aluminum-based composite material prepared according to any one of claims 1-4 is applied in the high-temperature range of 200℃-400℃; under high-temperature conditions, the tensile strengths at 200℃, 300℃, and 400℃ can reach 446MPa, 311MPa, and 201MPa, respectively, and the elongations are 9.9%, 10.6%, and 6.1%, respectively.

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