Nanometer Al3Ti reinforced aluminum-based composite material and preparation method thereof

Abstract

The invention provides a nanometer Al3Ti reinforced aluminum-based composite material and a preparation method thereof, and relates to the technical field of aluminum-based composites.The preparation method comprises the following steps that MAX-phase ceramic particles and aluminum raw material powder are mixed and then subjected to first ball milling treatment, and first mixed powder is obtained; wherein the MAX phase ceramic particles are micron-sized ceramic particles; the first mixed powder is heated, the MAX phase reacts with Al to form A13Ti, and second mixed powder is obtained; the second mixed powder is subjected to second ball milling treatment, and third mixed powder is obtained; wherein the average particle size of A13Ti in the third mixed powder is nanoscale; and the third mixed powder is subjected to aftertreatment, and the nanometer Al3Ti reinforced aluminum matrix composite is obtained. According to the method, a nanometer strengthening phase is introduced into an aluminum matrix in a rough-to-fine mode, and the problem that when nanometer raw material powder is directly added, nanometer particles are agglomerated, and consequently the strength and plasticity of the composite material are poor is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum matrix composites, and particularly relates to a nano-Al3Ti reinforced aluminum matrix composite and a preparation method thereof. Background Art

[0002] Due to its excellent high strength, high modulus, and high thermal stability, aluminum matrix composites show extremely broad application prospects in the fields of rail transit, aerospace, military equipment, etc. In the design and preparation process of aluminum matrix composites, the selection of the reinforcement phase is crucial, directly affecting the processing performance and service performance of the materials. Although traditional micron reinforcements can improve strength, they are prone to cause interfacial defects, leading to premature fracture due to stress concentration at the interface. In contrast, nano reinforcements can produce significant grain refinement strengthening, dislocation pinning, and stress regulation effects at extremely low addition amounts, enabling the composites to maintain good plasticity and toughness. Therefore, introducing nano reinforcements is considered a key way to break through the performance bottleneck of aluminum matrix composites.

[0003] Currently, the industry generally adopts the preparation idea of "using the fine to make the fine" to introduce nano reinforcements. For example, directly adding nano-Al2O3, or in-situ generating nano-Al2O3 by adding nano-TiO2. However, this preparation method has many drawbacks: on the one hand, the production cost of nano particles is high, and strict environmental conditions are required during storage and transportation, and factors such as humidity and temperature need to be strictly controlled to prevent the agglomeration or performance degradation of nano particles; on the other hand, there is a strong van der Waals force between nano particles, resulting in easy agglomeration of the particles and difficult to achieve uniform dispersion in the matrix material, thus greatly limiting its effect in practical applications; among them, stress concentration is easy to occur at the interface between the agglomerates and the matrix, inducing crack initiation and leading to premature fracture of the material when stressed; unevenly distributed nano particles are prone to cause local deformation of the matrix and reduce the overall plasticity; that is, nano particle agglomeration is prone to result in poor strength and plasticity of the composite material; in addition, the safety issues of nano particles during preparation and use have also attracted wide attention, and the potential hazards of nano particles to the health of operators and the environment also increase the protection cost and management difficulty during their use.

[0004] In view of this, it is necessary to provide a preparation method for nano particle reinforced aluminum matrix composites. Summary of the Invention

[0005] Therefore, the present invention provides a nano-Al3Ti reinforced aluminum matrix composite and a preparation method thereof, which can solve the problem of poor strength and plasticity of nano reinforced aluminum matrix composites in the prior art.

[0006] To solve the above problems, the present invention provides a preparation method for a nano-Al3Ti reinforced aluminum matrix composite, comprising the following steps:

[0007] Step 1): Mix MAX phase ceramic particles with aluminum raw material powder and then conduct the first ball milling treatment to obtain the first mixed powder; wherein, the MAX phase ceramic particles are micron-sized ceramic particles;

[0008] Step 2): Heat-treat the first mixed powder to cause the MAX phase to react with Al to form Al3Ti, and obtain the second mixed powder; the second mixed powder includes Al powder and Al3Ti powder;

[0009] Step 3): Conduct the second ball milling treatment on the second mixed powder to obtain the third mixed powder; wherein, the third mixed powder includes Al powder and nano-sized Al3Ti powder;

[0010] Step 4): Conduct post-treatment on the third mixed powder to obtain a nano-Al3Ti reinforced aluminum matrix composite.

[0011] Further, in the said Step 1):

[0012] The MAX phase ceramic particles are one of Ti2AlC ceramic particles, Ti3AlC2 ceramic particles, and Ti3SiC2 ceramic particles; and / or

[0013] The average particle size of the MAX phase ceramic particles is 10 - 100 μm; and / or

[0014] The aluminum raw material powder is one or more of aluminum powder, aluminum alloy powder, and a mixed powder of aluminum powder and alloy element powder; and / or

[0015] The average particle size of the aluminum raw material powder is 1 - 50 μm; and / or

[0016] In the first mixed powder, the mass fraction of the MAX phase ceramic particles is 1 - 25 wt.%.

[0017] Further, in the said Step 1):

[0018] In the first ball milling treatment, the weight ratio of balls to materials is 5:1 - 30:1; and / or

[0019] The rotation speed of the first ball milling treatment is 100 - 200 rpm; and / or

[0020] The time of the first ball milling treatment is 10 - 30 h; and / or

[0021] The first ball milling treatment is carried out in an argon atmosphere; and / or

[0022] In the first mixed powder, the average particle size of the MAX phase ceramic particles is less than 1 μm.

[0023] Further, the heat treatment in step 2) is carried out in a vacuum atmosphere; and / or

[0024] The heat treatment includes: heating the first mixed powder to 550 - 580 °C and holding for 2 - 5 h; and / or

[0025] The average particle size of A13Ti in the second mixed powder is less than 1 μm, and A13Ti has agglomeration.

[0026] Further, in step 3):

[0027] The weight ratio of balls to materials in the second ball milling treatment is 5:1 - 30:1; and / or

[0028] The rotation speed of the second ball milling treatment is 300 - 500 rpm; and / or

[0029] The time of the second ball milling treatment is 3 - 6 h; and / or

[0030] The second ball milling treatment is carried out in an argon atmosphere; and / or

[0031] The average particle size of A13Ti in the third mixed powder is 50 - 200 nm, and among them, A13Ti is dispersedly distributed in the aluminum matrix.

[0032] Further, in step 4):

[0033] The post - treatment of the third mixed powder includes: successively carrying out cold pressing forming treatment, powder metallurgy sintering treatment and plastic processing treatment on the third mixed powder.

[0034] Further, the pressure used in the cold pressing forming treatment is 60 - 120 MPa.

[0035] Further, the powder metallurgy sintering treatment adopts one of vacuum hot - pressing sintering treatment, hot isostatic pressing treatment, and spark plasma sintering treatment; and / or

[0036] The temperature of the powder metallurgy sintering treatment is 580 - 650 °C, with a pressure of 80 - 200 MPa; the time of the powder metallurgy sintering treatment is 0.5 - 1 h.

[0037] Further, the temperature of the plastic processing treatment is 400 - 630 °C; and / or

[0038] The method of the plastic processing treatment is one of forging, rolling, and extrusion.

[0039] On the other hand, the present invention provides a nano-Al3Ti reinforced aluminum matrix composite material. The microstructure of the nano-Al3Ti reinforced aluminum matrix composite material includes nano-A13Ti and an aluminum matrix; the nano-A13Ti is dispersedly distributed in the aluminum matrix;

[0040] wherein, the average particle size of the nano-A13Ti is 50 - 200 nm; the volume fraction of the nano-A13Ti is 2 - 42 vol.%;

[0041] the elastic modulus of the nano-Al3Ti reinforced aluminum matrix composite material is 80 - 130 GPa, the tensile strength is 350 - 650 MPa, and the fracture elongation is 1 - 15%;

[0042] Preferably, the nano-Al3Ti reinforced aluminum matrix composite material is obtained by using the preparation method described in any one of the above.

[0043] The nano-Al3Ti reinforced aluminum matrix composite material and its preparation method provided by the present invention have the following beneficial effects:

[0044] 1. On the one hand, the present invention provides a preparation method of a nano-Al3Ti reinforced aluminum matrix composite material, including the following steps: mixing MAX phase ceramic particles and aluminum raw material powder and then performing a first ball milling treatment to obtain a first mixed powder; wherein, the MAX phase ceramic particles are micron-sized ceramic particles; heating the first mixed powder to make the MAX phase react with Al to form A13Ti and obtain a second mixed powder; performing a second ball milling treatment on the second mixed powder to obtain a third mixed powder; wherein, the average particle size of A13Ti in the third mixed powder is nanoscale; performing a post-treatment on the third mixed powder to obtain a nano-Al3Ti reinforced aluminum matrix composite material; based on the above method, the present invention uses micron-sized MAX phase ceramic particles as raw materials, refines the MAX phase ceramic particles through the first ball milling treatment, and makes the MAX phase dispersedly distributed in the aluminum matrix; then makes the MAX phase react with Al to form A13Ti through the heating treatment; then refines A13Ti through the second ball milling treatment to obtain a mixed powder of nano-A13Ti and Al, thereby fully exerting the strengthening effect of the nano-strengthening phase, and finally obtaining a nano-Al3Ti reinforced aluminum matrix composite material through the post-treatment; it should be noted that the present invention introduces the nano-strengthening phase into the aluminum matrix in a "coarse to fine" manner, avoiding the problem that the strength and plasticity of the composite material are poor due to the agglomeration of nano-particles when directly adding nano raw material powder. At the same time, using micron-sized MAX phase ceramic particles as raw materials can reduce the preparation cost of the composite material and avoid the storage and transportation difficulties and safety problems when using nano-phases as raw materials.

[0045] 2. Further, micron-sized MAX phase ceramic particles are used based on the raw material powder. In the first mixed powder, the mass fraction of the MAX phase ceramic particles is only 1-25 wt.%. The lower content of the MAX phase can reduce the wear of the grinding balls during the ball milling process, increase the service life of the grinding balls, and at the same time reduce the iron impurities in the composite material, thereby ensuring the strength and plasticity of the composite material.

[0046] 3. Further, in the first ball milling treatment, a low rotation speed and long-time ball milling method are adopted. The grinding balls collide with the MAX phase ceramic particles, causing the MAX phase to deform and break, and generating a sufficient number of high-energy surfaces. At the same time, Al elements diffuse into the high-energy defects of the MAX phase, providing a fast diffusion channel for Al atoms to enter the MAX phase during the subsequent heat treatment to promote the reaction between the MAX phase and Al during the heat treatment; among them, the selection of the rotation speed and time, on the one hand, avoids excessive ball milling energy leading to premature cold welding of the aluminum raw material powder, causing the MAX phase to be wrapped by aluminum powder, resulting in too much unreacted MAX phase remaining in the composite material and affecting the performance of the composite material; on the other hand, avoids too low ball milling energy leading to insufficient shear action on the MAX phase and failing to obtain sufficiently fine MAX phase and a sufficient number of high-energy surfaces.

[0047] 4. On the other hand, the present invention provides a nano-Al3Ti reinforced aluminum matrix composite material, which is obtained by using the preparation method of any one of the above. The microstructure of the nano-Al3Ti reinforced aluminum matrix composite material includes nano-A13Ti and an aluminum matrix; among them, the nano-A13Ti is dispersedly distributed in the aluminum matrix; the average particle size of the nano-A13Ti is 50-200 nm; the volume fraction of the nano-A13Ti is 2-42 vol.%. The high content characteristic of A13Ti can effectively improve the strength and elastic modulus of the composite material. The characteristics of nano-size and dispersed distribution are beneficial to alleviating the interfacial stress concentration and avoiding premature failure. The elastic modulus of the nano-Al3Ti reinforced aluminum matrix composite material is 80-130 GPa, the tensile strength is 350-650 MPa, and the fracture elongation is 1-15%. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. The drawings in the following description are only exemplary. For those of ordinary skill in the art, without creative efforts, other implementation drawings can be obtained based on the provided drawings.

[0049] Figure 1 It is a scanning electron microscope image of the Ti2AlC-Al mixed powder in Example 1 of the present invention;

[0050] Figure 2It is the scanning electron microscope image of the nano A13Ti reinforced aluminum matrix composite in Embodiment 2 of the present invention;

[0051] Figure 3 It is the scanning electron microscope image of the (Ti2AlC + A13Ti) / Al composite material in Comparative Example 2 of the present invention;

[0052] Figure 4 It is the transmission electron microscope image of the Al2O3 / Al composite material in Comparative Example 6 of the present invention. Detailed implementation manners

[0053] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the attached drawings required for the description of the embodiments or the prior art. The attached drawings in the following description are only exemplary. For those of ordinary skill in the art, without creative efforts, other implementation drawings can also be obtained based on the provided drawings.

[0054] The present invention provides a preparation method for a nano Al3Ti reinforced aluminum matrix composite material, including the following steps:

[0055] Step 1): Mix MAX phase ceramic particles with aluminum raw material powder and perform a first ball milling treatment to obtain a first mixed powder;

[0056] Among them, the MAX phase ceramic particles are one of Ti2AlC ceramic particles, Ti3AlC2 ceramic particles, and Ti3SiC2 ceramic particles; the average particle size of the MAX phase ceramic particles is 10 - 100 μm; the aluminum raw material powder is one or more of aluminum powder, aluminum alloy powder, and a mixed powder of aluminum powder and alloy element powder; the average particle size of the aluminum raw material powder is 1 - 50 μm;

[0057] The first ball milling treatment is carried out in an argon atmosphere. The weight ratio of balls to materials during ball milling is 5:1 - 30:1, the rotation speed of the ball mill is 100 - 200 rpm, and the time of the first ball milling treatment is 10 - 30 h;

[0058] In the first mixed powder after the first ball milling treatment, the mass fraction of the MAX phase ceramic particles is 1 - 25 wt.%, and the average particle size of the MAX phase ceramic particles is less than 1 μm.

[0059] Step 2): In a vacuum atmosphere, heat the first mixed powder to 550 - 580 °C and keep it warm for 2 - 5 h to make the MAX phase react with Al to form A13Ti, and obtain a second mixed powder; the average particle size of A13Ti in the second mixed powder is less than 1 μm, and A13Ti exists in agglomeration.

[0060] Step 3): In an argon atmosphere, perform a second ball milling treatment on the second mixed powder to obtain a third mixed powder;

[0061] During the second ball milling treatment, the weight ratio of balls to materials is 5:1 - 30:1, the rotation speed of the ball mill is 300 - 500 rpm, and the time of the second ball milling treatment is 3 - 6 h; in the third mixed powder after the second ball milling treatment, the average particle size of A13Ti is 50 - 200 nm; among them, aluminum powder (A1 powder) forms a matrix as a continuous phase, while nano A13Ti is embedded as a dispersed phase therein, and A13Ti is uniformly distributed in the aluminum matrix.

[0062] Step 4): Cold pressing, powder metallurgy sintering, and plastic processing are successively performed on the third mixed powder to obtain a nano-Al3Ti reinforced aluminum matrix composite;

[0063] Among them, the pressure used for the cold pressing treatment is 60 - 120 MPa; the powder metallurgy sintering treatment adopts one of vacuum hot pressing sintering treatment, hot isostatic pressing treatment, and spark plasma sintering treatment, and the temperature of the powder metallurgy sintering treatment is 580 - 650 °C, the pressure is 80 - 200 MPa, and the time is 0.5 - 1 h; the plastic processing treatment adopts one of forging, rolling, and extrusion, and the temperature of the plastic processing treatment is 400 - 630 °C.

[0064] Based on the above method, the present invention uses micron-sized MAX phase ceramic particles as raw materials, refines the MAX phase ceramic particles through the first ball milling treatment, and makes the MAX phase disperse in the aluminum matrix; then, through the heat treatment, the MAX phase reacts with Al to form A13Ti; then, through the second ball milling treatment, A13Ti is refined to obtain a mixed powder of nano A13Ti and Al, so as to fully exert the strengthening effect of the nano-strengthening phase. Finally, through the post-treatment, a nano-Al3Ti reinforced aluminum matrix composite is obtained; it should be noted that the present invention introduces the nano-strengthening phase into the aluminum matrix in a "coarse to fine" manner, avoiding the problem that the strength and plasticity of the composite material are poor due to the agglomeration of nano-particles when directly adding nano raw material powders. At the same time, using micron MAX phase ceramic particles as raw materials can reduce the preparation cost of the composite material and avoid the storage and transportation difficulties and safety problems when using nano-phases as raw materials. After the heat treatment, elements such as C and Si in the MAX phase are retained in A13Ti, and the elements in the Al alloy exist in the matrix in the forms of solute atom clusters, solid solutions, precipitates, etc.

[0065] Al3Ti has characteristics such as low density and high strength, and can form a lower interfacial mismatch with Al; at the same time, as an intermetallic compound, Al3Ti can deform when bearing loads and has a high deformation compatibility with the Al matrix.

[0066] Based on raw materials powder, micron-sized MAX phase ceramic particles are used. In the first mixed powder, the mass fraction of the MAX phase ceramic particles is only 1-25 wt.%. The lower content of the MAX phase can reduce the wear of the grinding balls during the ball milling process, increase the service life of the grinding balls, and at the same time reduce the iron impurities in the composite material, thus avoiding the reduction of the strength and plasticity of the composite material.

[0067] In addition, in the first ball milling treatment, a low rotational speed and long ball milling time are adopted. The grinding balls collide with the MAX phase ceramic particles, causing the MAX phase to deform and break, and generating a sufficient number of high-energy surfaces. At the same time, Al elements diffuse into the high-energy defects of the MAX phase, providing a fast diffusion channel for Al atoms to enter the MAX phase during the subsequent heat treatment, so as to promote the reaction between the MAX phase and Al during the heat treatment. Among them, the selection of the rotational speed and time, on the one hand, avoids excessive ball milling energy causing premature cold welding of the aluminum raw material powder, resulting in the MAX phase being wrapped by aluminum powder before being refined, leaving too much unreacted MAX phase in the composite material and affecting the performance of the composite material; on the other hand, it avoids too low ball milling energy resulting in insufficient shear action on the MAX phase and failing to obtain sufficiently fine MAX phase and a sufficient number of high-energy surfaces.

[0068] The temperature during the heat treatment is selected to be 550-580 °C, which can avoid the phenomena of aluminum powder consolidation and coarsening of Al3Ti during high-temperature heating. At the same time, since no pressure is applied during the heating process, there is no deformation of the powder, and the generated Al3Ti agglomerates around the MAX phase.

[0069] In the second ball milling treatment, a higher ball milling rotational speed and shorter ball milling time are adopted to further refine and uniformly disperse Al3Ti, so as to fully exert the strengthening effect of the nano-strengthening phase. Different from the ball milling refinement of the MAX phase particles, the Al3Ti particles are already distributed in the aluminum matrix and are small in size. High-energy ball milling is required to shear, deform and cold weld the Al3Ti-Al powder, so as to further refine the Al3Ti particles.

[0070] The powder metallurgy sintering treatment adopts a high-temperature and short-time process to close the pores in the composite material, thereby obtaining a dense bulk material. At the same time, the coarsening phenomenon of Al3Ti caused by high temperature is avoided.

[0071] On the other hand, the present invention provides a nano-Al3Ti reinforced aluminum matrix composite material, which is obtained by using the preparation method of any one of the above. The microstructure of the nano-Al3Ti reinforced aluminum matrix composite material includes nano-A13Ti and an aluminum matrix; the nano-A13Ti is dispersedly distributed in the aluminum matrix; wherein, the average particle size of the nano-A13Ti is 50-200 nm; the volume fraction of the nano-A13Ti is 2-42 vol.%. Compared with the traditional A13Ti / Al composite material, the composite material of the present application has finer A13Ti size and higher A13Ti content, and has fewer unreacted particles (MAX phase), with a content lower than 2 wt.%. Therefore, the obtained nano-A13Ti / Al composite material has a more uniform microstructure and higher heat resistance.

[0072] The present invention will be further described below in conjunction with specific examples and comparative examples.

[0073] Example 1

[0074] The present example provides a preparation method of a nano-Al3Ti reinforced aluminum matrix composite material, including the following steps:

[0075] Step 1): Mix 90 g of Ti2AlC particles (average particle size of 10 μm) with 910 g of aluminum powder (average particle size of 1 μm), and then perform the first ball milling treatment for 10 h using a stirring high-energy ball mill under an argon atmosphere to obtain a Ti2AlC-Al mixed powder (the first mixed powder);

[0076] Among them, the ball-to-material weight ratio during the first ball milling treatment is 5:1 (5 kg of grinding balls), and the rotation speed of the stirring high-energy ball mill is 200 rpm; in the Ti2AlC-Al mixed powder after the first ball milling treatment, the average particle size of the Ti2AlC particles is less than 1 μm.

[0077] Step 2): Under a vacuum atmosphere, heat the Ti2AlC-Al mixed powder to 550 °C and keep it warm for 5 h to obtain a second mixed powder; the average particle size of A13Ti in the second mixed powder is less than 1 μm, and A13Ti agglomerates.

[0078] Step 3): Under an argon atmosphere, perform the second ball milling treatment on 1000 g of the second mixed powder for 3 h to obtain a nano-A13Ti-Al powder;

[0079] Among them, the ball-to-material weight ratio during the second ball milling treatment is 5:1 (5 kg of grinding balls), and the rotation speed of the stirring high-energy ball mill is 500 rpm; in the third mixed powder after the second ball milling treatment, the average particle size of A13Ti is about 120 nm, and A13Ti is evenly distributed in the aluminum matrix.

[0080] Step 4): Cold-press the above-mentioned third mixed powder, and then perform vacuum hot-pressing sintering treatment at 580 °C and 200 MPa for 1 h to obtain a sintered ingot; then extrude the sintered ingot at 500 °C to obtain a nano-Al3Ti reinforced aluminum matrix composite material; wherein, the extrusion ratio is 7:1.

[0081] In this embodiment, the scanning morphology of the Ti2AlC-Al mixed powder is as Figure 1 shown. Among them, the particles with white contrast are Ti2AlC, and the matrix with black contrast is the Al matrix. It can be seen that the Ti2AlC particles have obvious fragmentation and refinement, showing a long strip shape, and accompanied by irregular (step-shaped) interfaces. The average particle size is less than 1 μm, and the Ti2AlC particles are dispersedly distributed in the Al matrix. Flaky Ti2AlC has a higher specific surface area, and the irregular interface can provide more Al3Ti nucleation sites, thereby promoting the reaction between Ti2AlC and Al during heating, which is beneficial to the formation of a nano-Al3Ti with a dispersed distribution in the final composite material. The nano-Al3Ti reinforced aluminum matrix composite material obtained in this embodiment has a uniform structure. Among them, the particle size of A13Ti is about 120 nm, the content of unreacted Ti2AlC is less than 2 wt.%, and the relative density is higher than 98%.

[0082] Example 2

[0083] This embodiment provides a method for preparing a nano-Al3Ti reinforced aluminum matrix composite material, including the following steps:

[0084] Step 1): Mix 120 g of Ti2AlC particles (average particle size of 50 μm) with 880 g of aluminum powder (average particle size of 25 μm), and then perform the first ball milling treatment for 20 h using a stirred high-energy ball mill under an argon atmosphere to obtain a Ti2AlC-Al mixed powder (the first mixed powder);

[0085] Among them, the ball-to-material weight ratio during the first ball milling treatment is 15:1 (15 kg of grinding balls), and the rotation speed of the stirred high-energy ball mill is 150 rpm; in the Ti2AlC-Al mixed powder after the first ball milling treatment, the average particle size of the Ti2AlC particles is less than 1 μm.

[0086] Step 2): Under a vacuum atmosphere, heat the Ti2AlC-Al mixed powder to 570 °C and hold for 3.5 h to obtain a second mixed powder; the average particle size of A13Ti in the second mixed powder is less than 1 μm, and A13Ti exists in agglomeration.

[0087] Step 3): Under an argon atmosphere, perform the second ball milling treatment on 1000 g of the second mixed powder for 5 h to obtain a nano-A13Ti-Al powder;

[0088] Among them, the ball-to-material weight ratio during the second ball milling treatment is 15:1 (15 kg of grinding balls), and the rotational speed of the stirred high-energy ball mill is 400 rpm; in the third mixed powder after the second ball milling treatment, the average particle size of A13Ti is about 180 nm, and A13Ti is uniformly distributed in the aluminum matrix.

[0089] Step 4): Cold-press and form the above-mentioned third mixed powder, and then carry out vacuum hot-pressing sintering treatment at 630 °C and 200 MPa for 0.5 h to obtain a sintered ingot; then extrude the sintered ingot at 500 °C to obtain a nano-Al3Ti reinforced aluminum matrix composite material; among them, the extrusion ratio is 7:1.

[0090] In this embodiment, the scanning morphology of the obtained nano-Al3Ti reinforced aluminum matrix composite material is as Figure 2 shown, where the particles with white contrast in the figure are A13Ti, and the matrix with black contrast is the Al matrix. The A13Ti particles are roughly equiaxed and uniformly distributed in the Al matrix. When the equiaxed A13Ti bears stress, it has a more uniform interfacial stress distribution than the common rod-shaped or block-shaped A13Ti, which helps to avoid premature failure caused by interfacial stress concentration. The nano-Al3Ti reinforced aluminum matrix composite material obtained in this embodiment has a uniform structure, among which the average particle size of A13Ti is about 180 nm, and the content of unreacted Ti2AlC is less than 2 wt.%. The density of this composite material is higher than 98%, the tensile strength is about 530 MPa, the fracture elongation is about 5%, and the elastic modulus is about 95 GPa.

[0091] Example 3

[0092] This embodiment provides a method for preparing a nano-Al3Ti reinforced aluminum matrix composite material, including the following steps:

[0093] Step 1): Mix 250 g of Ti3SiC2 particles (average particle size of 100 μm) with 750 g of aluminum powder (average particle size of 50 μm), and then carry out the first ball milling treatment for 30 h using a stirred high-energy ball mill under an argon atmosphere to obtain a Ti3SiC2-Al mixed powder (the first mixed powder);

[0094] Among them, the ball-to-material weight ratio during the first ball milling treatment is 30:1 (30 kg of grinding balls), and the rotational speed of the stirred high-energy ball mill is 100 rpm; in the Ti3SiC2-Al mixed powder after the first ball milling treatment, the average particle size of the Ti3SiC2 particles is less than 1 μm.

[0095] Step 2): Under a vacuum atmosphere, heat the Ti3SiC2-Al mixed powder to 580 °C and keep it warm for 2 h to obtain a second mixed powder; the average particle size of A13Ti in the second mixed powder is less than 1 μm, and A13Ti exists in agglomeration.

[0096] Step 3): Under an argon atmosphere, the second ball milling treatment is carried out on 1000 g of the second mixed powder for 6 h using a stirred high-energy ball mill to obtain nano-sized A13Ti-Al powder;

[0097] Among them, the ball-to-material weight ratio during the second ball milling treatment is 30:1 (30 kg of grinding balls), and the rotation speed of the stirred high-energy ball mill is 300 rpm; in the third mixed powder after the second ball milling treatment, the average particle size of A13Ti is about 200 nm, and A13Ti is uniformly distributed in the aluminum matrix.

[0098] Step 4): Cold press the above-mentioned third mixed powder into a shape, and then carry out vacuum hot press sintering treatment at 650 °C and 200 MPa for 0.5 h to obtain a sintered ingot; then extrude the sintered ingot at 500 °C to obtain a nano-sized Al3Ti-reinforced aluminum matrix composite material; among them, the extrusion ratio is 7:1.

[0099] The nano-sized Al3Ti-reinforced aluminum matrix composite material obtained in this embodiment has a uniform structure. Among them, the average particle size of A13Ti is about 200 nm, the content of unreacted Ti3SiC2 is less than 2 wt.%, and the relative density is higher than 98%.

[0100] Comparative Example 1

[0101] This comparative example provides a method for preparing a nano-sized Al3Ti-reinforced aluminum matrix composite material, including the following steps:

[0102] Step 1): Mix 120 g of Ti2AlC particles (average particle size of 50 μm) with 880 g of aluminum powder (average particle size of 25 μm), and then under an argon atmosphere, carry out the first ball milling treatment for 20 h using a stirred high-energy ball mill to obtain Ti2AlC-Al mixed powder;

[0103] Among them, the ball-to-material weight ratio during the first ball milling treatment is 15:1 (15 kg of grinding balls), and the rotation speed of the stirred high-energy ball mill is 600 rpm; in the Ti2AlC-Al mixed powder after the first ball milling treatment, the particle size distribution of Ti2AlC particles is uneven and the particle size range is relatively wide, about 1 - 20 μm.

[0104] Step 2): Under a vacuum atmosphere, heat the Ti2AlC-Al mixed powder to 570 °C and keep it warm for 3.5 h to obtain (Ti2AlC + A13Ti)-Al powder.

[0105] Step 3): Under an argon atmosphere, 1000 g of the above (Ti2AlC+Al13Ti)-Al powder was subjected to a second ball milling treatment for 5 h using a stirred high-energy ball mill to obtain a refined (Ti2AlC+Al13Ti)-Al powder, wherein the average particle size of Al13Ti was about 180 nm, and the Ti2AlC was flaky with an average particle size of less than 1 μm;

[0106] The weight ratio of the balls to the materials during the second ball milling process was 15:1 (15 kg of grinding balls), and the rotation speed of the stirring high-energy ball mill was 400 rpm.

[0107] Step 4): The third mixed powder is cold pressed and then vacuum hot pressed and sintered at 630°C and 200 MPa for 0.5 h to obtain a sintered ingot; the sintered ingot is then extruded at 500°C to obtain a nano-Al3Ti reinforced aluminum-based composite material; wherein the extrusion ratio is 7:1.

[0108] In this comparative example, due to the excessively high ball milling energy (the ball milling speed is too high) of the Ti2AlC-Al mixed powder, cold welding occurred in the aluminum powder before the Ti2AlC particles were sheared and crushed, and the micron Ti2AlC particles were wrapped in the aluminum powder. The particle size distribution range was relatively wide, about 1-20 μm, and it failed to produce enough high-energy surfaces and particle size refinement, resulting in incomplete Ti2AlC reaction in the subsequent heating process. Although Ti2AlC was refined to a particle size less than 1 μm after the subsequent second ball milling process, the short-term sintering process resulted in the presence of more Ti2AlC particles (about 3 wt.%) in the matrix. The composite material had a tensile strength of about 400 MPa and an elongation at break of 5%.

[0109] Comparative Example 2

[0110] This comparative example provides a method for preparing a nano-Al3Ti reinforced aluminum-based composite material, comprising the following steps:

[0111] Step 1): 120 g of Ti2AlC particles (average particle size of 50 μm) and 880 g of aluminum powder (average particle size of 25 μm) were mixed, and then subjected to a first ball milling treatment for 20 h using a stirred high-energy ball mill under an argon atmosphere to obtain a Ti2AlC-Al mixed powder;

[0112] The ball-to-material weight ratio during the first ball milling treatment is 15:1 (15 kg of grinding balls), and the rotation speed of the stirring high-energy ball mill is 150 rpm. In the Ti2AlC-Al mixed powder after the first ball milling treatment, the average particle size of the Ti2AlC particles is less than 1 μm.

[0113] Step 2): Under a vacuum atmosphere, heat the Ti2AlC-Al mixed powder to 570 °C and hold for 0.5 h to obtain (Ti2AlC + A13Ti)-Al powder.

[0114] Step 3): Under an argon atmosphere, use a stirred high-energy ball mill to perform a second ball milling treatment on 1000 g of the above (Ti2AlC + A13Ti)-Al powder for 5 h to obtain refined (Ti2AlC + A13Ti)-Al powder, where the particle size of A13Ti is about 180 nm and the average particle size of Ti2AlC is less than 1 μm;

[0115] Among them, the ball-to-material weight ratio during the second ball milling treatment is 15:1 (15 kg of grinding balls), and the rotation speed of the stirred high-energy ball mill is 400 rpm.

[0116] Step 4): Cold press and form the above third mixed powder, and then perform vacuum hot pressing sintering treatment at 630 °C and 200 MPa for 0.5 h to obtain a sintered ingot; then extrude the sintered ingot at 500 °C to obtain a nano-Al3Ti reinforced aluminum matrix composite material; among them, the extrusion ratio is 7:1.

[0117] The scanning morphology of the nano-Al3Ti reinforced aluminum matrix composite material obtained in this comparative example is as Figure 3 shown, where the particles with white contrast in the figure are Ti2AlC, the particles with gray contrast are A13Ti, and the matrix with black contrast is the Al matrix. Due to the too short heat preservation time, a large number of unreacted Ti2AlC particles (mainly relatively coarse Ti2AlC particles) are distributed in the Al matrix. Most of the A13Ti agglomerates in the form of an interfacial reaction layer near the Ti2AlC-Al interface, and due to the small amount of A13Ti generated by the reaction of Ti2AlC, there are a large number of particle-free zones in the Al matrix, indicating that the composite material shows microscopic tissue inhomogeneity. The tensile strength of this composite material is about 410 MPa, and the fracture elongation is about 3%.

[0118] Comparative Example 3

[0119] This comparative example provides a method for preparing a nano-Al3Ti reinforced aluminum matrix composite material, including the following steps:

[0120] Step 1): Mix 120 g of Ti2AlC particles (average particle size of 50 μm) with 880 g of aluminum powder (average particle size of 25 μm), and then under an argon atmosphere, use a stirred high-energy ball mill to perform a first ball milling treatment for 20 h to obtain Ti2AlC-Al mixed powder;

[0121] Among them, the ball-to-material weight ratio during the first ball milling treatment is 15:1 (15 kg of grinding balls), and the rotation speed of the stirred high-energy ball mill is 150 rpm; in the Ti2AlC-Al mixed powder after the first ball milling treatment, the average particle size of the Ti2AlC particles is less than 1 μm.

[0122] Step 2): Under a vacuum atmosphere, heat the Ti2AlC-Al mixed powder to 650 °C and hold for 3.5 h to obtain an A13Ti / Al bulk.

[0123] In this comparative example, due to the excessive heat preservation time during heating, the mixed powder consolidated, and it was impossible to refine A13Ti by ball milling. Moreover, since no pressure was applied during the heating process, the in-situ A13Ti / Al bulk obtained was not dense, with a relative density lower than 60% and an elongation at break less than 1%.

[0124] Comparative Example 4

[0125] This comparative example provides a method for preparing a nano-Al3Ti reinforced aluminum matrix composite, including the following steps:

[0126] Step 1): Mix 120 g of Ti2AlC particles (average particle size of 50 μm) with 880 g of aluminum powder (average particle size of 25 μm), and then perform the first ball milling treatment for 20 h using a stirred high-energy ball mill under an argon atmosphere to obtain a Ti2AlC-Al mixed powder;

[0127] Among them, the ball-to-material weight ratio during the first ball milling treatment is 15:1 (15 kg of grinding balls), and the rotation speed of the stirred high-energy ball mill is 150 rpm; in the Ti2AlC-Al mixed powder after the first ball milling treatment, the average particle size of the Ti2AlC particles is less than 1 μm.

[0128] Step 2): Under a vacuum atmosphere, heat the Ti2AlC-Al mixed powder to 570 °C and hold for 3.5 h to obtain a second mixed powder; the average particle size of A13Ti in the second mixed powder is less than 1 μm, and A13Ti exists in agglomerates.

[0129] Step 3): Under an argon atmosphere, perform the second ball milling treatment on 1000 g of the second mixed powder for 5 h using a stirred high-energy ball mill to obtain a nano-A13Ti-Al powder;

[0130] Among them, the ball-to-material weight ratio during the second ball milling treatment is 15:1 (15 kg of grinding balls), and the rotation speed of the stirred high-energy ball mill is 100 rpm; in the third mixed powder after the second ball milling treatment, the average particle size of A13Ti is about 0.5 - 1 μm.

[0131] Step 4): Cold press the above third mixed powder into a shape, and then perform vacuum hot press sintering treatment at 630 °C and 200 MPa for 0.5 h to obtain a sintered ingot; then extrude the sintered ingot at 500 °C to obtain a nano-Al3Ti reinforced aluminum matrix composite material; wherein, the extrusion ratio is 7:1.

[0132] In this comparative example, due to the too low ball milling energy of the A13Ti-Al powder (too low rotation speed in the second ball milling treatment), the A13Ti particles did not break and refine, the A13Ti size was relatively coarse, and the average particle size was about 0.5 - 1 μm.

[0133] Comparative Example 5

[0134] This comparative example provides a preparation method of a nano-Al3Ti reinforced aluminum matrix composite material, including the following steps:

[0135] Step 1): Mix 120 g of Ti2AlC particles (average particle size of 50 μm) with 880 g of aluminum powder (average particle size of 25 μm), and then perform the first ball milling treatment for 20 h using a stirring high-energy ball mill under an argon atmosphere to obtain a Ti2AlC-Al mixed powder;

[0136] Among them, the ball-to-material weight ratio during the first ball milling treatment is 15:1 (15 kg of grinding balls), and the rotation speed of the stirring high-energy ball mill is 150 rpm; in the Ti2AlC-Al mixed powder after the first ball milling treatment, the average particle size of the Ti2AlC particles is less than 1 μm.

[0137] Step 2): Under a vacuum atmosphere, heat the Ti2AlC-Al mixed powder to 570 °C and hold for 3.5 h to obtain a second mixed powder; the average particle size of A13Ti in the second mixed powder is less than 1 μm, and A13Ti exists in agglomeration.

[0138] Step 3): Under an argon atmosphere, perform the second ball milling treatment on 1000 g of the second mixed powder for 5 h using a stirring high-energy ball mill to obtain a nano-A13Ti-Al powder;

[0139] Among them, the ball-to-material weight ratio during the second ball milling treatment is 15:1 (15 kg of grinding balls), and the rotation speed of the stirring high-energy ball mill is 400 rpm; in the third mixed powder after the second ball milling treatment, the particle size of A13Ti is about 180 nm, and A13Ti is uniformly distributed in the aluminum matrix.

[0140] Step 4): Cold press the above third mixed powder into a shape, and then perform vacuum hot press sintering treatment at 630 °C and 200 MPa for 10 h to obtain a sintered ingot; then extrude the sintered ingot at 500 °C to obtain a nano-Al3Ti reinforced aluminum matrix composite material; wherein, the extrusion ratio is 7:1.

[0141] In this comparative example, due to the excessively long hot pressing time of the nano A13Ti-Al powder, the A13Ti particles coarsened, resulting in a relatively coarse size of A13Ti, and its particle size distribution range was 1 - 10 μm.

[0142] Comparative Example 6

[0143] This comparative example provides a preparation method for obtaining a nano-Al2O3 reinforced aluminum matrix composite by using the fine to refine, including the following steps:

[0144] Step 1): Mix 120 g of nano-Al2O3 (average particle size of 10 nm) with 880 g of aluminum powder (average particle size of 25 μm), and then under an argon atmosphere, perform the first ball milling treatment for 10 h using a stirred high-energy ball mill to obtain an Al2O3-Al mixed powder;

[0145] Among them, the ball-to-material weight ratio during the ball milling treatment is 15:1 (15 kg of grinding balls), and the rotation speed of the stirred high-energy ball mill is 250 rpm.

[0146] Step 2): Cold press and form the above-mentioned third mixed powder, and then perform vacuum hot press sintering treatment at 630 °C and 200 MPa for 2 h to obtain a sintered ingot; then extrude the sintered ingot at 500 °C to obtain a nano-Al2O3 reinforced aluminum matrix composite; among them, the extrusion ratio is 7:1.

[0147] The scanning morphology of the nano-Al2O3 reinforced aluminum matrix composite obtained in this comparative example is as Figure 4 shown. Among them, the middle particles in the figure are Al2O3 aggregates, and the rest are the Al matrix. The van der Waals force between the nano-Al2O3 particles causes most of the Al2O3 to be in an agglomerated state, and most of them are distributed near the Al grain boundaries, and the microstructure uniformity is poor. At the same time, due to the too high content of nano-Al2O3, the elongation of the composite material is greatly reduced, less than 0.2%.

[0148] Comparative Example 7

[0149] This comparative example provides a preparation method for obtaining a nano-Al2O3 reinforced aluminum matrix composite by using the fine to refine, including the following steps:

[0150] Step 1): Mix 50 g of nano-Al2O3 (average particle size of 10 nm) with 950 g of aluminum powder (average particle size of 25 μm), and then under an argon atmosphere, perform the first ball milling treatment for 10 h using a stirred high-energy ball mill to obtain an Al2O3-Al mixed powder;

[0151] Among them, the ball-to-material weight ratio during the ball milling treatment is 15:1 (15 kg of grinding balls), and the rotation speed of the stirred high-energy ball mill is 250 rpm.

[0152] Step 2): Cold press and form the above-mentioned third mixed powder, and then conduct vacuum hot press sintering treatment at 630 °C and 200 MPa for 2 h to obtain a sintered ingot; then extrude the sintered ingot at 500 °C to obtain a nano-Al2O3 reinforced aluminum matrix composite material; wherein, the extrusion ratio is 7:1.

[0153] In the nano-Al2O3 reinforced aluminum matrix composite material obtained in this comparative example, most of the Al2O3 agglomerates near the Al grain boundaries, and the microstructural inhomogeneity is relatively high. The elastic modulus of this composite material is lower than 80 GPa, the tensile strength is about 350 MPa, and the fracture elongation is about 8%.

[0154] It is easy for those skilled in the art to understand that on the premise of no conflict, the advantageous technical features of the above-mentioned various methods can be freely combined and superimposed.

[0155] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention. The above is only the preferred implementation manner of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can still be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A preparation method of a nano-Al3Ti reinforced aluminum matrix composite material, characterized in that, It includes the following steps: Step 1): Mix MAX phase ceramic particles with aluminum raw material powder and then conduct the first ball milling treatment to obtain the first mixed powder; wherein, the MAX phase ceramic particles are micron-sized ceramic particles; Step 2): Conduct heat treatment on the first mixed powder to make the MAX phase react with Al to form Al3Ti, and obtain the second mixed powder; the second mixed powder includes Al powder and Al3Ti powder; Step 3): Conduct the second ball milling treatment on the second mixed powder to obtain the third mixed powder; wherein, the third mixed powder includes Al powder and nano-sized Al3Ti powder; Step 4): Conduct post-treatment on the third mixed powder to obtain a nano-Al3Ti reinforced aluminum matrix composite.

2. The preparation method of the nano-Al3Ti reinforced aluminum matrix composite material according to claim 1, characterized in that, In the said Step 1): The MAX phase ceramic particles are one of Ti2AlC ceramic particles, Ti3AlC2 ceramic particles, and Ti3SiC2 ceramic particles; and / or The average particle size of the MAX phase ceramic particles is 10 - 100 μm; and / or The aluminum raw material powder is one or more of aluminum powder, aluminum alloy powder, and a mixed powder of aluminum powder and alloy element powder; and / or The average particle size of the aluminum raw material powder is 1 - 50 μm; and / or In the first mixed powder, the mass fraction of the MAX phase ceramic particles is 1 - 25 wt.%.

3. The preparation method of the nano-Al3Ti reinforced aluminum matrix composite material according to claim 1, characterized in that In the said Step 1): In the first ball milling treatment, the ball-to-material weight ratio is 5:1 - 30:1; and / or The rotation speed of the first ball milling treatment is 100 - 200 rpm; and / or The time of the first ball milling treatment is 10 - 30 h; and / or The first ball milling treatment is carried out in an argon atmosphere; and / or In the first mixed powder, the average particle size of the MAX phase ceramic particles is less than 1 μm.

4. The preparation method of the nano-Al3Ti reinforced aluminum matrix composite material according to claim 1, characterized in that, The heat treatment in the said Step 2) is carried out in a vacuum atmosphere; and / or The heat treatment includes: heating the first mixed powder to 550 - 580 °C and holding for 2 - 5 h; and / or The average particle size of Al3Ti in the second mixed powder is less than 1 μm.

5. The preparation method of the nano-Al3Ti reinforced aluminum matrix composite according to claim 1, characterized in that In the said Step 3): In the second ball milling treatment, the ball-to-material weight ratio is 5:1 - 30:1; and / or The rotation speed of the second ball milling treatment is 300 - 500 rpm; and / or The time of the second ball milling treatment is 3 - 6 h; and / or The second ball milling treatment is carried out in an argon atmosphere; and / or In the third mixed powder, the average particle size of Al3Ti is 50 - 200 nm, and Al3Ti is dispersed in the aluminum matrix.

6. The preparation method of the nano-Al3Ti reinforced aluminum matrix composite material according to claim 1, characterized in that In the said Step 4): Conducting post-treatment on the third mixed powder includes: sequentially conducting cold pressing forming treatment, powder metallurgy sintering treatment, and plastic processing treatment on the third mixed powder.

7. The preparation method of the nano-Al3Ti reinforced aluminum matrix composite according to claim 6, characterized in that, The pressure used in the cold pressing forming treatment is 60 - 120 MPa.

8. The preparation method of the nano-Al3Ti reinforced aluminum matrix composite according to claim 6, characterized in that, The powder metallurgy sintering treatment adopts one of vacuum hot pressing sintering treatment, hot isostatic pressing treatment, and spark plasma sintering treatment; and / or The temperature of the powder metallurgy sintering treatment is 580 - 650 °C, pressurized 80 - 200 MPa; the time of the powder metallurgy sintering treatment is 0.5 - 1 h.

9. The preparation method of the nano-Al3Ti reinforced aluminum matrix composite according to claim 6, characterized in that, The temperature of the plastic processing treatment is 400 - 630 °C; and / or The plastic processing treatment method is one of forging, rolling, and extrusion.

10. A nano-Al3Ti reinforced aluminum matrix composite, characterized in that, The microstructure of the nano-Al3Ti reinforced aluminum matrix composite includes nano-A13Ti and an aluminum matrix; the nano-A13Ti is dispersedly distributed in the aluminum matrix; wherein, the average particle size of the nano-A13Ti is 50 - 200 nm; the volume fraction of the nano-A13Ti is 2 - 42 vol.%; The elastic modulus of the nano-Al3Ti reinforced aluminum matrix composite is 80 - 130 GPa, the tensile strength is 350 - 650 MPa, and the fracture elongation is 1 - 15%; Preferably, the nano-Al3Ti reinforced aluminum matrix composite is obtained by the preparation method described in any one of claims 1 - 8.

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