Aluminum-based composite material and preparation method thereof

Abstract

The present invention relates to an aluminum-based composite material and a preparation method thereof, and relates to the technical field of metal-based composite material preparation. The main technical scheme adopted is: a preparation method of an aluminum-based composite material, comprising the following steps: ball milling micron-sized raw material powder into mixed elementary particles with a particle size of 0.3-5 mm; wherein the raw material powder includes matrix powder and ceramic reinforcement powder; cold pressing the mixed elementary particles into billets; and subjecting the billets to pressureless sintering to obtain aluminum-based composite material billets after pressureless sintering. The present invention prepares mixed elementary particles by ball milling to realize the preparation of an aluminum-based composite material with excellent performance by a pressureless sintering method, which changes the inherent processing mode of existing mechanical powder mixing-hot pressing sintering-plastic processing, improves processing efficiency while ensuring material performance.

Description

Technical Field

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

[0002] Aluminum-based composite materials are composite materials formed by adding ceramic reinforcements to an aluminum alloy matrix. Due to their excellent properties such as light weight, high modulus, high strength, and wear resistance, they have become key strategic materials in the fields of aerospace, nuclear power, national defense, transportation, etc.

[0003] At present, the process route adopted by the mainstream powder metallurgy method for preparing aluminum-based composite components mainly involves the following three steps: Step 1, mechanical powder mixing: make different types of powders fully and evenly mixed; Step 2, hot pressing sintering or hot isostatic pressing: realize the initial densification and alloying of aluminum-based composite materials; Step 3, plastic deformation processing: realize the crushing of continuous alumina film and further densification. Among them, the hot pressing sintering in step 2 has strict requirements on equipment conditions, and often requires the construction of special equipment. Only a single furnace and a single ingot can be produced each time, and the production efficiency is extremely low; while the equipment construction and use costs of hot isostatic pressing are high, and it is difficult to achieve hot isostatic pressing under large billets and high pressure conditions, resulting in the product size of aluminum-based composite materials being limited, and the density is difficult to ensure, and subsequent plastic processing must be relied on to achieve further densification and crushing of continuous alumina structure. It should be noted here that the preparation of aluminum-based composite materials is more difficult due to the presence of a continuous oxide film in aluminum powder, and the above problems exist. However, the powder metallurgy preparation of other metal-based composite materials does not require the above-mentioned complex preparation process.

[0004] Therefore, the current hot pressing sintering / hot isostatic pressing process has become a bottleneck limiting the efficiency and cost of aluminum-based composite material preparation, and has severely limited the application of aluminum-based composite materials in cost-sensitive fields. If the powder is directly used for pressureless sintering instead of hot pressing sintering, there will be problems such as poor powder interface bonding, high resistance to cold pressing deformation, and difficulty in dispersing reinforcement particles, which can easily cause problems such as billet breakage and inclusions in the subsequent processing process, making it difficult to obtain high-performance aluminum-based composite materials.

[0005] In summary, in order to obtain high-performance aluminum-based composite materials with light weight, high strength and high modulus, and promote their application in energy-saving and low-carbon industries, it is urgent to change the existing inherent processing mode of mechanical powder mixing-hot pressing sintering-plastic processing, improve processing efficiency while ensuring material performance. Summary of the invention

[0006] In view of this, the present invention provides an aluminum-based composite material and a preparation method thereof, the main purpose of which is to be able to prepare an aluminum-based composite material with excellent performance by a pressureless sintering method.

[0007] In order to achieve the above object, the present invention mainly provides the following technical solutions:

[0008] On the one hand, an embodiment of the present invention provides a method for preparing an aluminum-based composite material, which comprises the following steps:

[0009] Ball milling step: ball milling the micron-sized raw material powder into mixed elementary particles with a particle size of 0.3-5 mm; wherein the raw material powder includes matrix powder and ceramic reinforcement powder;

[0010] Cold pressing step: cold pressing the mixed elementary particles into ingots;

[0011] Pressureless sintering step: performing pressureless sintering on the billet to obtain an aluminum-based composite material billet after pressureless sintering.

[0012] Preferably, in the ball milling step, the ball-to-material ratio is (10:1)-(20:1), the ball milling time is 30-50 minutes, and the ball milling speed is 150-200 revolutions per minute.

[0013] Preferably, the matrix powder includes aluminum powder and / or aluminum alloy powder; preferably, the matrix powder also includes alloy element powder; further preferably, the alloy element in the alloy element powder includes one or more of zinc, copper, magnesium, silicon and iron.

[0014] Preferably, in the raw material powder: the volume fraction of the matrix powder is 75-95%, and the volume fraction of the ceramic reinforcement powder is 5-25%.

[0015] Preferably, the ceramic reinforcement powder is one or more of silicon carbide, boron carbide, and aluminum oxide; and / or the particle sizes of the ceramic reinforcement powder and matrix powder are both 1-100 μm; and / or the ceramic reinforcement particles in the mixed elementary particles are uniformly distributed; and / or in the ball milling step, the mixed elementary particles formed by ball milling are in a dispersed state.

[0016] Preferably, in the cold pressing step: the pressure of the cold pressing is not less than 50 MPa.

[0017] Preferably, in the pressureless sintering step: the pressureless sintering temperature is 600-650° C., and the pressureless sintering time is not less than 1.5 hours.

[0018] Preferably, after the pressureless sintering step, the method further comprises:

[0019] Plastic processing step: plastic processing is performed on the billet after the pressureless sintering treatment to obtain an aluminum-based composite material part.

[0020] Preferably, the temperature of the plastic deformation processing is 350-550°C.

[0021] On the other hand, an embodiment of the present invention further provides an aluminum-based composite material, wherein the aluminum-based composite material is prepared by the preparation method of the aluminum-based composite material described in any one of the above items; preferably, the aluminum-based composite material is an aluminum-based composite material ingot or an aluminum-based composite material part.

[0022] Compared with the prior art, the aluminum-based composite material and the preparation method thereof of the present invention have at least the following advantages:

[0023] Beneficial effects:

[0024] The embodiment of the present invention provides a method for preparing an aluminum-based composite material, which mainly includes the following steps: ball milling the raw material powder into mixed elementary particles with a particle size of 0.3-5 mm; cold pressing the mixed elementary particles into billets; and pressureless sintering the billets to obtain aluminum-based composite material billets after pressureless sintering. Here, regarding the above steps: on the one hand, since there is no need to use hot pressing equipment or hot isostatic pressing equipment, the energy consumption of the material preparation process is significantly reduced, the degree of dependence on special equipment is reduced, and it can be operated using a general press and sintering furnace, which reduces the threshold for material preparation. On the other hand, the ball milling process (different from the ball milling of the prior art, the ball milling is to ball mill small-sized raw material powder into large-sized particles) is used to solve the problem of reduced oxide film crushing links and insufficient alloying caused by the lack of hot pressing or hot isostatic pressing links, and ensure stable and reliable material performance. During the ball milling process, the original powder is impacted and kneaded by the ball to form large mixed elementary particles. The impact of the original powder will promote the breakage of the oxide film, and the kneading to form large-sized mixed elementary particles will inhibit the formation of new oxide film, reduce the proportion of oxide film, and also increase the contact between different powders, promoting alloying. If the original powder is ball-milled into smaller nanopowders, the specific surface area of ​​the powder will increase, the proportion of oxide film will increase, and the contact between powders will be weakened, which will have a huge hindering effect on metallurgical bonding. The cost of ball milling equipment is significantly lower than that of hot pressing equipment or hot isostatic pressing equipment. This method can solve the problems of oxide film, alloying and other issues that affect material properties without significantly increasing the equipment cost.

[0025] Furthermore, the preparation method of an aluminum-based composite material provided by the embodiment of the present invention can realize batch or continuous production in the ball milling, cold pressing and pressureless sintering stages, which can significantly increase the preparation and processing efficiency of aluminum-based composite material components and reduce the preparation and processing cost of materials. In the ball milling stage, a large-capacity ball mill or multiple ball mills can be used in parallel to obtain a large number of mixed elementary particles; in the cold pressing stage, forging presses and other equipment can be used, combined with molds and demolding tools to achieve continuous production of cold-pressed billets. If cold isostatic pressing equipment is used, powder billets can also be pressed in batches in a single furnace; in the pressureless sintering stage, batch sintering can be performed in a single furnace.

[0026] Furthermore, a method for preparing an aluminum-based composite material provided in an embodiment of the present invention can achieve near-net forming of aluminum-based composite material parts through two deformation / forming steps of cold pressing and plastic processing, thereby improving material utilization, reducing machining steps, and thus reducing the cost of part products.

[0027] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a scanning electron microscope photograph of the hybrid elementary particles;

[0029] Figure 2 The cylindrical ingot is obtained by cold isostatic pressing and sintering the mixed elementary particles;

[0030] Figure 3 It is a cup-shaped aluminum matrix composite die forging sample;

[0031] Figure 4 This is a scanning electron microscope photograph of loose chips of the ingot after sintering in Comparative Example 1. DETAILED DESCRIPTION

[0032] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention application are described in detail below in conjunction with the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures, or characteristics in one or more embodiments may be combined in any suitable form.

[0033] The preparation method of an aluminum-based composite material proposed in the present invention is a new concept proposed for the first time. It is based on the preparation of aluminum-based composite materials based on mixed elementary particles. Specifically, the method uses ball milling granulation technology to ball-mill micron-sized raw material powder into large-sized elementary particles (it should be noted here that: the prior art uses ball milling technology to ball-mill large-sized particles into small-sized particles; and the present invention is different from the prior art. The present invention uses ball milling technology to ball-mill the raw material mixture into large-sized particles). Then, a powder billet is prepared by cold pressing. This step mainly presses the raw material powder into a billet by mold cold pressing, cold isostatic pressing, etc. Subsequently, pressureless sintering is performed. Finally, the pressureless sintered billet is deformed by plastic processing methods (such as extrusion and forging), and finally an aluminum-based composite material with excellent structure density and performance is obtained.

[0034] Here, what needs to be explained about the “mixed elementary particles” is that in terms of microstructure, the mixed elementary particles prepared by the present invention are a solid entity mixed with reinforcement particles and matrix metal powder, and their size can reach the millimeter level, while mechanical powder mixing is a powder mixture of loose reinforcement and matrix, and its powder size is generally at the micrometer level. In terms of preparation method, mechanical powder mixing uses lower energy input and does not require the use of ball milling equipment, while the present invention requires the use of ball milling equipment, a higher ball-to-material ratio, and strict control of ball milling process parameters to achieve the preparation of millimeter-level mixed elementary particles. These differences can ensure that alloying and densification have begun to be achieved between the reinforcement and the matrix during the ball milling stage, and the alloying and densification requirements for subsequent processing are relatively low, so that better alloying and densification effects can be obtained without the use of hot pressing sintering. It should be emphasized that: for aluminum-based composite materials, the degree of crushing, alloying and densification of the aluminum powder surface oxide film of mechanical powder mixing is difficult to achieve the effect of mixed elementary particles, and the performance after pressureless sintering is very poor, so it is difficult to perform plastic processing. Even if plastic processing can be performed, the final material performance is low because the aluminum powder surface oxide film is not crushed and the alloying degree is poor (this problem does not exist for other metal-based composite materials). The present invention uses mixed elementary particles as raw materials, and achieves preliminary alloying and densification in the ball milling stage, so it can overcome the defects of mechanical powder mixing.

[0035] The present invention utilizes cold pressing and pressureless hot sintering to replace the hot pressing sintering / hot isostatic pressing steps in the traditional method, which are heavily dependent on equipment, have low production efficiency and high cost, and can realize the batch acquisition of sintered powder billets. Compared with hot pressing sintering / hot isostatic pressing, the method of the present invention can greatly improve the utilization efficiency of the sintering furnace and achieve energy conservation and emission reduction. Secondly, by regulating the two-stage forming of cold pressing and plastic processing, a part structure with a more complex shape can be directly obtained, the amount of machining can be reduced, and the material utilization rate can be improved. The use of this technology can greatly reduce the production cost and energy consumption of aluminum-based composite materials and improve the preparation efficiency. The method of the present invention utilizes ball milling to prepare mixed elementary particles, which replaces the original mixed powder, can improve the interface bonding between powders in the powder pretreatment stage, break the cracked ceramic reinforcement in advance, reduce the specific surface area of ​​the powder, refine the aluminum alloy grains, and can reduce the deformation resistance of the subsequent cold pressing process, and improve the density of the billet after cold pressing.

[0036] The present invention mainly utilizes the ball milling method to solve the problems of difficulty in breaking the oxide film on the surface of aluminum powder, high deformation resistance during cold pressing, and poor metallurgical bonding ability between powders. The prepared mixed elementary particles are large-sized spherical particles with uniformly distributed ceramic reinforcements. Although the present invention also adopts the ball milling method to prepare aluminum-based composite materials, there are essential differences in technical details and effects from the related technology of the prior art ball milling method for regulating the microscopic distribution structure of aluminum-based composite materials (as mentioned above, the prior art utilizes the ball milling process, mainly to ball mill large-sized particles into small-sized particles, or to use ball milling to change the shape of the original powder (such as from spherical to flaky); and the present invention is different from the prior art. The present invention utilizes ball milling technology to mix the raw materials and ball-mill them into large-sized particles).

[0037] Specifically, the technical solution of the present invention is as follows:

[0038] Ball milling step: ball mill the raw material powder into mixed elementary particles with a particle size of 0.3-5 mm.

[0039] In the ball milling step, in order to ball mill the raw material powder into large-sized mixed elementary particles, the ball milling parameters are set as follows: the ball-to-material ratio is (10:1)-(20:1), preferably 15:1. The ball milling time is 30-50 minutes, and the ball milling speed is 150-200 revolutions per minute. It should be noted that for the raw material powder of the present invention, the above-mentioned process parameters (ball-to-material ratio, ball milling time, and speed) are used to obtain mixed elementary particles (roughly spherical) with a particle size of 0.3-5 mm. If it is not within the above-mentioned process parameter range, fine particle size or block particles will generally be obtained, which is not required by the present invention.

[0040] Preferably, the raw material powder includes matrix powder and ceramic reinforcement powder. The matrix powder includes aluminum powder and / or aluminum alloy powder; further, the matrix powder also includes alloy element powder; the alloy element in the alloy element powder is one or more of zinc, copper, magnesium, silicon and iron.

[0041] Preferably, the volume ratio of the matrix powder to the ceramic reinforcement powder is (75-95):(5-25).

[0042] Preferably, the ceramic reinforcement powder is one or more of silicon carbide, boron carbide and aluminum oxide.

[0043] Cold pressing process step: cold pressing the mixed elementary particles into billets.

[0044] The cold pressing process can be performed using a mold and a press, or by cold isostatic pressing to press the powder in the package. By adjusting the size and structure of the mold and package, powder ingots with different shape characteristics can be obtained by cold pressing to facilitate subsequent processing.

[0045] In order to obtain a powder ingot with good density and shape-deformability, the pressure applied during cold pressing should generally not be less than 50 MPa.

[0046] Pressureless sintering step: performing pressureless sintering on the billet to obtain an aluminum-based composite material billet after pressureless sintering.

[0047] The pressureless sintering temperature is determined according to the type of matrix aluminum alloy, which is generally 600-650°C. The sintering time is determined according to the size of the part, which is generally not less than 1.5 hours.

[0048] Plastic processing step: plastic processing is performed on the billet after the pressureless sintering treatment to obtain an aluminum-based composite material part.

[0049] The main purpose of plastic processing is to achieve the densification of the powder after sintering, and at the same time, to break part of the oxide film through large deformation.

[0050] Plastic processing uses different deformation methods such as die forging and extrusion, and the plastic processing temperature is generally 400-500°C. For use scenarios with lower requirements for material toughness, plastic processing can be omitted.

[0051] The present invention is further described below by specific embodiments:

[0052] Example 1

[0053] This example prepares a SiC particle reinforced aluminum-based composite rod with a volume fraction of 15%. The raw material powder: the particle size of the SiC particles is 7 microns, and the matrix uses aluminum powder and alloy element powder with a particle size of 13 microns. 780.1 grams of aluminum powder, 37.3 grams of copper powder, 12.4 grams of magnesium powder, and 170.1 grams of SiC powder are used to prepare a SiC-reinforced 2009 aluminum composite material with a volume fraction of 15%.

[0054] The main preparation steps are as follows:

[0055] Ball milling step: ball mill the raw material powder to prepare 1 kg of mixed elementary particles with a particle size of 0.4-3 mm. Figure 1 The ball milling process parameters are as follows: ball-to-material ratio is 15:1, ball milling speed is 200 rpm, and ball milling time is 30 minutes.

[0056] Cold pressing processing steps: the mixed elementary particles are loaded into a cylindrical rubber sheath with an inner diameter of 90 mm, and cold isostatic pressing is performed (wherein the cold isostatic pressing pressure is 100 MPa) to obtain a cold isostatic pressed ingot.

[0057] Pressureless sintering steps: Place the cold isostatic pressed ingot into a pressureless sintering furnace, heat it from room temperature to 620°C, and sinter it for 2 hours. Use machining to trim the shape of the ingot after sintering to obtain a cylindrical ingot, such as Figure 2 shown.

[0058] Plastic processing step: The cylindrical ingot is subjected to extrusion deformation processing with an extrusion ratio of 16:1 to obtain a dense aluminum-based composite material rod.

[0059] The aluminum-based composite material rod prepared in this embodiment was tested for mechanical properties, wherein the yield strength of the material was 410 MPa, the tensile strength was 570 MPa, and the elongation was 5%.

[0060] Example 2

[0061] This embodiment prepares a SiC particle reinforced aluminum-based composite rod with a volume fraction of 15%. Among them, the raw material powder: the particle size of the SiC particles is 7 microns, and the matrix uses aluminum powder and alloy element powder with a particle size of 13 microns. 780.1 grams of aluminum powder, 37.3 grams of copper powder, 12.4 grams of magnesium powder, and 170.1 grams of SiC powder are used to prepare a SiC reinforced 2009 aluminum composite material with a volume fraction of 15%.

[0062] The main preparation steps are as follows:

[0063] Ball milling step: ball mill the above raw materials to prepare 1 kg of mixed elementary particles with a particle size of 0.4-3 mm. Figure 1 The ball milling process parameters are as follows: ball-to-material ratio is 15:1, ball milling speed is 200 rpm, and ball milling time is 30 minutes.

[0064] Cold pressing processing steps: put the mixed elementary particles into a cylindrical rubber sheath with an inner diameter of 80 mm, perform cold isostatic pressing (the cold isostatic pressing pressure is 100 MPa), and obtain the cold isostatic pressed ingot.

[0065] Pressureless sintering steps: Place the cold isostatic pressed ingot into a pressureless sintering furnace, heat it from room temperature to 620°C, and sinter it for 2 hours. Use machining to trim the shape of the ingot after sintering to obtain a cylindrical ingot, such as Figure 2 shown.

[0066] Plastic processing step: The cylindrical ingot is subjected to extrusion deformation processing with an extrusion ratio of 16:1 to obtain a dense aluminum-based composite material rod.

[0067] The aluminum-based composite material rod prepared in this embodiment was tested for mechanical properties, wherein the yield strength of the material was 412 MPa, the tensile strength was 569 MPa, and the elongation was 4.7%.

[0068] Example 3

[0069] This embodiment prepares a SiC particle reinforced aluminum-based composite rod with a volume fraction of 15%. Among them, the raw material powder: the particle size of the SiC particles is 13 microns, and the matrix uses aluminum powder and alloy element powder with a particle size of 13 microns. 1465.7 grams of aluminum powder, 124.9 grams of zinc powder, 28.3 grams of copper powder, 46.6 grams of magnesium powder, and 334.4 grams of SiC powder are used to prepare a SiC reinforced 7xxx series aluminum-based composite material with a volume fraction of 15%.

[0070] The main preparation steps are as follows:

[0071] Ball milling step: ball mill the above raw materials to prepare 1 kg of mixed elementary particles with a particle size of 0.3-3 mm. The ball milling process parameters are as follows: ball-to-material ratio is 15:1, ball milling speed is 200 rpm, and ball milling time is 35 minutes.

[0072] Cold pressing processing steps: load the mixed elementary particles into a cylindrical mold with an inner diameter of 60 mm, and use a press to perform cold pressing, wherein the cold pressing pressure is 80 MPa, and after cold pressing, a cylindrical ingot with a diameter of 60 mm is obtained.

[0073] Pressureless sintering step: Place the cylindrical billet in a pressureless sintering furnace, heat from room temperature to 615°C, and sinter for 1.5 hours. Use machining to trim the shape of the billet after sintering to obtain a cylindrical billet for die forging.

[0074] Plastic processing step: The cylindrical ingot is subjected to die forging deformation processing to obtain a cup-shaped part of an aluminum-based composite material with a dense structure, such as Figure 3 shown.

[0075] Mechanical property tests were performed on a portion of the cup-shaped aluminum-based composite material prepared in this embodiment. The yield strength of the material was 560 MPa, the tensile strength was 630 MPa, and the elongation was 2.0%.

[0076] Comparative Example 1

[0077] Comparative Example 1: A SiC particle reinforced aluminum-based composite rod with a volume fraction of 15% was prepared. The raw material: the particle size of the SiC particles was 7 microns, and the matrix used aluminum powder and alloy element powder with a particle size of 13 microns. 780.1 grams of aluminum powder, 37.3 grams of copper powder, 12.4 grams of magnesium powder, and 170.1 grams of SiC powder were used to prepare a SiC reinforced 2009 aluminum composite material with a volume fraction of 15%.

[0078] The specific preparation steps are as follows:

[0079] Only the raw material powders are mixed, and no ball milling and granulation operation is performed. The mixed powder is loaded into a cylindrical mold with an inner diameter of 80 mm, and a press is used for cold pressing. After cold pressing, a cylindrical ingot with a diameter of 80 mm is obtained, which is put into a pressureless sintering furnace, heated from room temperature to 620 degrees Celsius, and sintered for 2 hours. After sintering, the powder is loosely combined and has a morphology such as Figure 4 As shown. The cylindrical billet for extrusion processing can be obtained without machining to trim the shape of the billet after sintering. Then, the cylindrical billet is subjected to extrusion deformation processing with an extrusion ratio of 16:1 to obtain an aluminum-based composite rod.

[0080] The aluminum-based composite material rod prepared in this comparative example was subjected to mechanical property tests, wherein the yield strength of the material was 360 MPa, the tensile strength was 480 MPa, and the elongation was 3.4%. Compared with Example 1, the aluminum-based composite material rod prepared in Comparative Example 1 had incomplete oxide film breakage, poor metallurgical bonding, and a significant decrease in material strength and plasticity.

[0081] Comparative Example 2

[0082] Comparative Example 2: A SiC particle reinforced aluminum-based composite rod with a volume fraction of 15% was prepared. The raw material powder: the particle size of the SiC particles was 13 microns, and the matrix used aluminum powder and alloy element powder with a particle size of 13 microns. 1465.7 grams of aluminum powder, 124.9 grams of zinc powder, 28.3 grams of copper powder, 46.6 grams of magnesium powder, and 334.4 grams of SiC powder were used to prepare a SiC-reinforced 7xxx series aluminum-based composite material with a volume fraction of 15%.

[0083] The specific preparation steps are as follows:

[0084] Only the raw material powders are mixed, and no ball milling and granulation operation is performed. 200 grams of the mixed powder is loaded into a cylindrical mold with an inner diameter of 60 mm, and a press is used for cold pressing. After cold pressing, a cylindrical billet with a diameter of 60 mm is obtained, which is put into a pressureless sintering furnace, heated from room temperature to 615 degrees Celsius, and sintered for 1.5 hours. The cylindrical billet for die forging can be obtained without machining to trim the shape of the billet after sintering. The cylindrical billet is subjected to die forging deformation processing to obtain an aluminum-based composite cup-shaped part.

[0085] The mechanical properties of the aluminum-based composite cup-shaped parts prepared in this comparative example were tested by sampling. The yield strength of the material was 560MPa, the tensile strength was 580MPa, and the elongation was 0.5%. Compared with Example 3, the aluminum-based composite cup-shaped parts prepared in Comparative Example 2 had higher strength due to the 7xxx aluminum matrix, but due to the incomplete crushing of the oxide film and the poor metallurgical bonding between the reinforcement and the matrix, the elongation of the material was significantly reduced.

[0086] Comparative Example 3

[0087] Comparative Example 3: A SiC particle reinforced aluminum matrix composite rod with a volume fraction of 15% was prepared. The raw material powder: SiC particles had a particle size of 7 microns, and the matrix used aluminum powder and alloy element powder with a particle size of 13 microns. 780.1 grams of aluminum powder, 37.3 grams of copper powder, 12.4 grams of magnesium powder, and 170.1 grams of SiC powder were used to prepare a SiC reinforced 2009 aluminum composite material with a volume fraction of 15%.

[0088] The specific preparation steps are as follows:

[0089] Only the matrix powder is subjected to high-energy ball milling, and the ball milling process is: the ball-to-material ratio is 15:1, the ball milling speed is 250 rpm, and the ball milling is 10 hours. The spherical matrix powder is ball-milled into a flaky matrix powder of 1-100 microns in size, and then the flaky matrix powder is mechanically mixed with SiC powder. The mixed powder is loaded into a cylindrical mold with an inner diameter of 80 mm, and a press is used for cold pressing with a pressure of 80 MPa. After cold pressing, a cylindrical billet with a diameter of 80 mm is obtained, which is placed in a pressureless sintering furnace, heated from room temperature to 620 degrees Celsius, and sintered for 2 hours. After sintering, the powder is loosely bonded. The cylindrical billet for extrusion processing can be obtained without machining to trim the shape of the billet after sintering. Then, the cylindrical billet is subjected to extrusion deformation processing with an extrusion ratio of 16:1 to obtain an aluminum-based composite material rod.

[0090] The aluminum-based composite material rod prepared in this comparative example was subjected to mechanical property tests, wherein the yield strength of the material was 490 MPa, the tensile strength was 520 MPa, and the elongation was 1.5%. Compared with Example 1, the oxide film of the aluminum-based composite material rod prepared in Comparative Example 3 was not completely broken, and the metallurgical bonding between the reinforcement and the matrix was poor, resulting in a significant decrease in the work hardening ability and elongation of the material.

[0091] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A method for preparing an aluminum-based composite material, characterized in that: It includes the following steps: Ball milling step: ball milling the micron-sized raw material powder into mixed elementary particles with a particle size of 0.3-5 mm; wherein the raw material powder includes matrix powder and ceramic reinforcement powder; wherein the ball-to-material ratio is (10:1)-(20:1), the ball milling time is 30-50 minutes, and the ball milling speed is 150-200 revolutions per minute; and the particle sizes of the ceramic reinforcement powder and the matrix powder are both 1-100 μm; Cold pressing step: cold pressing the mixed elementary particles into ingots; Pressureless sintering step: performing pressureless sintering on the billet to obtain an aluminum-based composite material billet after pressureless sintering.

2. The method for preparing the aluminum-based composite material according to claim 1, characterized in that: The matrix powder includes aluminum powder and / or aluminum alloy powder.

3. The method for preparing the aluminum-based composite material according to claim 2, characterized in that: The matrix powder also includes alloy element powder.

4. The method for preparing the aluminum-based composite material according to claim 3, characterized in that: The alloy elements in the alloy element powder include one or more of zinc, copper, magnesium, silicon and iron.

5. The method for preparing the aluminum-based composite material according to claim 1, characterized in that: In the raw material powder, the volume fraction of the matrix powder is 75-95%, and the volume fraction of the ceramic reinforcement powder is 5-25%.

6. The method for preparing the aluminum-based composite material according to claim 1, characterized in that: The ceramic reinforcement powder is one or more of silicon carbide, boron carbide and aluminum oxide; and / or The ceramic reinforcement particles are uniformly distributed in the mixed elementary particles; and / or In the ball milling step, the mixed elementary particles formed by ball milling are in a dispersed state.

7. The method for preparing the aluminum-based composite material according to claim 1, characterized in that: In the cold pressing step: The pressure of cold pressing is not less than 50MPa.

8. The method for preparing the aluminum-based composite material according to claim 1, characterized in that: In the pressureless sintering step: The temperature of pressureless sintering is 600-650°C, and the time of pressureless sintering is not less than 1.5 hours.

9. The method for preparing the aluminum-based composite material according to claim 1, characterized in that: After the pressureless sintering step, the method further comprises: Plastic processing step: plastic processing is performed on the billet after the pressureless sintering treatment to obtain an aluminum-based composite material part.

10. The method for preparing the aluminum-based composite material according to claim 9, characterized in that: The temperature of the plastic working is 350-550°C.

11. An aluminum-based composite material, characterized in that: The aluminum-based composite material is prepared by the method for preparing the aluminum-based composite material according to any one of claims 1 to 10.

12. The aluminum-based composite material according to claim 11, characterized in that: The aluminum-based composite material is an aluminum-based composite material ingot or an aluminum-based composite material piece.

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