Heterogeneous-configuration aluminum-based composite material as well as preparation method and application thereof

Abstract

The invention relates to a heterogeneous aluminum-based composite material as well as a preparation method and application thereof. The aluminum-based composite material comprises a matrix, a reinforcing phase and a nano precipitated phase, the matrix is Al crystal grains with the average particle size of 10-30 microns, the reinforcing phase is AlLiCu alloy crystal grains with the average particle size of 300-500 microns, and the nano precipitated phase is Al2Cu and Al2CuLi. According to the aluminum-based composite material disclosed by the invention, the aluminum-based composite material is synergistically reinforced through a coarse and fine crystal configuration (heterogeneous configuration) and a nano precipitated phase, the tensile strength can be improved, meanwhile, the elongation at break is not obviously reduced, good obdurability matching is shown, and the aluminum-based composite material is high in density and hardness.

Description

Technical Field

[0001] The present invention relates to the technical field of powder metallurgy materials, and more specifically, to a heterogeneous aluminum matrix composite material, a preparation method thereof, and an application thereof. Background Art

[0002] Aluminum (Al) matrix composite materials have characteristics such as high specific strength, high specific modulus, high-temperature creep resistance, fatigue resistance, wear resistance, and low coefficient of thermal expansion, and are key materials indispensable for the high-quality development of key fields such as China's automobile manufacturing, information communication, aerospace, and nuclear power. At present, Al matrix composite materials mainly use ceramic particles (such as SiC, B4C, Al2O3, or TiB2) and fibers (such as carbon fibers or carbon nanotubes (CNTs)) as reinforcement phases. However, the composite materials prepared using the above reinforcement phases generally have an obvious inversion of strength and toughness, that is, while the strength of the composite material is improved (the tensile strength is increased), its toughness will decrease significantly (the fracture elongation rate decreases significantly, less than 50% of the fracture elongation rate of aluminum). One of the reasons is that the wettability between the reinforcement phase and the Al matrix is poor, and it is difficult to form a strong bonding interface with the Al matrix. For example, in a Chinese patent for an aluminum matrix composite material and a preparation method thereof, although the strength of the aluminum matrix composite material prepared using nano-SiC particles as the reinforcement phase is improved, the elongation rate decreases significantly.

[0003] Therefore, it is urgent to develop an aluminum matrix composite material that exhibits good strength-toughness matching. Summary of the Invention

[0004] The primary object of the present invention is to overcome the problem of obvious inversion of strength and toughness existing in the above-mentioned existing aluminum matrix composite materials, and provide an aluminum matrix composite material. The aluminum matrix composite material of the present invention can synergistically reinforce the aluminum matrix composite material through a fine and coarse grain configuration (heterogeneous configuration) and nano-precipitated phases, so as to achieve an increase in tensile strength without a significant decrease in the fracture elongation rate, exhibit good strength-toughness matching, and the aluminum matrix composite material has a high density and high hardness.

[0005] A further object of the present invention is to provide a preparation method for a heterogeneous aluminum matrix composite material.

[0006] The above objects of the present invention are achieved by the following technical solutions:

[0007] A heterogeneous aluminum matrix composite material, the aluminum matrix composite material comprising a matrix, a reinforcement phase, and nano-precipitated phases;

[0008] The matrix is Al grains with an average particle size of 10 - 30 μm, the reinforcement phase is AlLiCu alloy grains with an average particle size of 300 - 500 μm, and the nano-precipitated phases are Al2Cu and Al2CuLi.

[0009] The aluminum-based composite material of the present invention can achieve improved tensile strength without significantly decreasing elongation at break by synergistically reinforcing the aluminum-based composite material through coarse and fine crystal configuration (heterogeneous configuration) and nano-precipitated phase, showing good strength-toughness matching. The aluminum-based composite material has high density, few macroscopic defects (such as cracks and voids), and high hardness, which is conducive to the preparation of parts with good surface quality and high dimensional accuracy.

[0010] The specific principle is: in the aluminum-based composite material of the present invention, Al grains with a certain average particle size are distributed around AlLiCu alloy grains with a certain average particle size, so that the Al grains are distributed in a continuous network, forming a specific coarse and fine crystal configuration (heterogeneous configuration), and a specific nano-precipitated phase is in situ formed on the surface of the AlLiCu alloy grains to form a coherent interface with the matrix, thereby improving the wettability of the matrix and the reinforcement phase, forming a good interface bonding, so that the aluminum-based composite material of the present invention can achieve an increase in tensile strength while the elongation at break does not decrease significantly, showing a good match between strength and toughness, and high density and hardness.

[0011] If there are no AlLiCu alloy grains, or the average grain size of the AlLiCu alloy grains is too small or too large, it will not be possible to form a specific coarse and fine crystal configuration (heterogeneous configuration), thus affecting the strength and toughness matching of the aluminum-based composite material. If there is no specific nano-precipitated phase, it will affect the wettability of the matrix and the reinforcement phase, thus affecting the strength and toughness matching of the aluminum-based composite material.

[0012] Preferably, the particle size distribution of the nano-precipitated phase is 50 to 500 nm.

[0013] Preferably, the AlLiCu alloy grains include the following components by mass percentage: Al: 95-98%, Cu: 1.5-4%, Li: 0.5-1%.

[0014] Preferably, the mass of the matrix accounts for 50-90% of the total mass of the aluminum-based composite material.

[0015] Preferably, the sum of the masses of the reinforcement phase and the nano-precipitated phase accounts for 10-50% of the total mass of the aluminum-based composite material.

[0016] A method for preparing an aluminum-based composite material with a heterogeneous configuration comprises the following steps: aluminum powder and AlLiCu alloy powder are mixed to obtain composite powder, and the composite powder is hot-pressed, sintered and hot-rolled to obtain the aluminum-based composite material.

[0017] The raw materials (AlLiCu alloy powder) of the preparation method of the aluminum-based composite material of the present invention are easy to obtain and low in cost. At the same time, the preparation method of the aluminum-based composite material of the present invention adopts a dry grinding process, does not require equipment to remove solvents and powder flake treatment, has low equipment requirements, and is simple in production process.

[0018] Preferably, the mass percentage of the AlLiCu alloy powder in the composite powder is 10-50%, and the mass percentage of the aluminum powder is 50-90%.

[0019] Preferably, the average particle size of the aluminum powder is 1-3 μm. When the aluminum powder with this average particle size is used and subjected to hot pressing sintering and hot rolling, Al grains with an average particle size of 10-30 μm will be formed.

[0020] Preferably, the purity of the aluminum powder is not less than 99.9%, and the shape is spherical.

[0021] Preferably, the average particle size of the AlLiCu alloy powder is 5-25 μm. When the AlLiCu alloy powder with this average particle size is used and subjected to hot pressing sintering and hot rolling, AlLiCu alloy grains with an average particle size of 300-500 μm will be formed.

[0022] Preferably, by mass percentage, the AlLiCu alloy powder comprises the following components: Al: 95-98%, Cu: 1.5-4%, Li: 0.5-1%.

[0023] Preferably, the purity of the AlLiCu alloy powder is not less than 99.9%, and the shape is spherical.

[0024] Preferably, the aluminum powder and / or the AlLiCu alloy powder are subjected to gas atomization treatment before mixing.

[0025] Preferably, the mixing process is: ball milling is carried out under a protective atmosphere.

[0026] More preferably, the protective atmosphere is at least one of argon or helium.

[0027] More preferably, the conditions of the ball milling include: the rotation speed is 100-200 r / min, the ball-to-material ratio is (3-5):1, and the time is 6-12 h.

[0028] Preferably, the temperature of the hot pressing sintering is 550-630 °C.

[0029] More preferably, it is heated to the temperature at a heating rate of 50-110 °C / min.

[0030] Preferably, the time of the hot pressing sintering is 0.5-3 h.

[0031] Preferably, the pressure of the hot pressing sintering is 20-60 MPa.

[0032] Preferably, the hot pressing sintering is carried out in a vacuum environment.

[0033] Preferably, the hot rolling has a rolling reduction of 20 to 50%.

[0034] Preferably, the hot rolling is performed under vacuum.

[0035] The application of the above aluminum-based composite materials in the fields of automobile manufacturing, information communication, aerospace or nuclear power also falls within the protection scope of the present invention.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The aluminum-based composite material of the present invention can achieve an increase in tensile strength while not significantly decreasing the elongation at break by synergistically reinforcing the aluminum-based composite material through coarse and fine crystal configuration (heterogeneous configuration) and nano-precipitated phase, showing a good match between strength and toughness. In addition, the aluminum-based composite material has a high density, few macroscopic defects (such as cracks and voids), and high hardness, which is conducive to the preparation of parts with good surface quality and high dimensional accuracy.

[0038] (2) The raw materials (AlLiCu alloy powder) of the preparation method of the aluminum-based composite material of the present invention are easily available and low in cost. At the same time, the preparation method of the aluminum-based composite material of the present invention adopts a dry grinding process, does not require equipment to remove solvents and powder flake treatment, has low equipment requirements, and is simple in production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is an optical microscope image of the aluminum-based composite material of Example 1.

[0040] Figure 2 This is the XRD diagram of the aluminum-based composite material of Example 1.

[0041] Figure 3 The SEM image and energy spectrum of the aluminum-based composite material of Example 1, wherein: Figure 3 A is the SEM image, Figure 3 B is Figure 3 A is the energy spectrum scan of the white dashed box.

[0042] Figure 4 TEM image, inverse Fourier transform image and Fourier transform image of the aluminum-based composite material of Example 1, wherein: Figure 4 A is the TEM image, Figure 4 B is Figure 4 A is a local enlarged TEM image. Figure 4 C is Figure 4 Inverse Fourier transform and Fourier transform of B.

[0043] Figure 5 TEM image and energy spectrum of the aluminum-based composite material of Example 1, wherein: Figure 5 A is the TEM image, Figure 5 B isFigure 5 Energy spectrum scanning diagram of the white dotted square box in A Figure 5 C is the element distribution map. Specific implementation mode

[0044] In order to describe the technical solution of the present invention more clearly and completely, the present invention will be further described in detail below through specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, and various changes can be made within the scope defined by the rights of the present invention.

[0045] Embodiment 1

[0046] This embodiment provides a heterogeneous aluminum matrix composite material, including a matrix, a reinforcing phase, and a nano-precipitation phase; the matrix is Al grains with an average particle size of 20 μm, the reinforcing phase is AlLiCu alloy grains with an average particle size of 500 μm, and the nano-precipitation phase is Al2Cu and Al2CuLi; by mass percentage, the AlLiCu alloy grains include the following components: Al: 95%, Cu: 4%, Li: 1%; the particle size distribution of the nano-precipitation phase is 50 - 500 nm; the mass of the matrix accounts for 50% of the total mass of the aluminum matrix composite material; the sum of the masses of the reinforcing phase and the nano-precipitation phase accounts for 50% of the total mass of the aluminum matrix composite material.

[0047] This embodiment provides a preparation method for a heterogeneous aluminum matrix composite material, including the following steps:

[0048] (1) Load the gas-atomized spherical aluminum powder (average particle size of 1 μm, purity of 99.9%) and the gas-atomized spherical AlLiCu alloy powder (average particle size of 25 μm, purity of 99.9%, and the gas-atomized spherical AlLiCu alloy powder includes the following components: Al: 95%, Cu: 4%, Li: 1%) into a stainless steel ball milling tank for ball milling and mixing, and fill argon as a protective atmosphere. The rotation speed of the ball mill is 100 r / min, the ball milling time is 12 h, and the ball-to-material ratio is 5:1 to obtain a composite powder; among them, the mass percentage of the gas-atomized spherical AlLiCu alloy powder in the composite powder is 50%.

[0049] (2) Load the composite powder into a graphite mold, and heat it to 600 °C at a heating rate of 110 °C / min under vacuum for hot pressing and sintering for 1 h, and the pressure of the hot pressing and sintering is 30 MPa.

[0050] (3) Cool down to 450 °C and keep it warm for 1 h, and then hot roll the material at 450 °C under vacuum conditions, and the rolling reduction is 20%, that is, the aluminum matrix composite material is obtained.

[0051] Take the aluminum matrix composite material of this embodiment for SEM characterization, and the results are as Figure 1 shown. From Figure 1It can be seen that in the aluminum-based composite material of Example 1, Al grains are distributed around the AlLiCu alloy grains, so that the Al grains are distributed in a continuous network; further calculation shows that the average particle size of the Al grains of the aluminum-based composite material of Example 1 is 20 μm, and the average particle size of the AlLiCu alloy grains is 500 μm.

[0052] The aluminum-based composite material of this embodiment was subjected to X-ray diffraction test (XRD), SEM characterization and energy spectrum test, and the results were as follows: Figures 2 - 3 As shown. Figure 2 It can be seen that the aluminum-based composite material of Example 1 has crystal diffraction peaks of Al, Al2Cu and Al2CuLi. Figure 2 and Figure 3 B knows that Figure 3 The white part in A is the nano-precipitated phase Al2Cu and Al2CuLi. Figure 2 The crystal diffraction peak of aluminum oxide also appears in the sample. This is because it is difficult to ensure that the entire hot rolling process is carried out under absolute vacuum conditions, which results in a very small amount of aluminum being oxidized.

[0053] The aluminum-based composite material of this embodiment was subjected to TEM characterization, Fourier transform characterization and energy spectrum test. The results are as follows: Figure 4 and Figure 5 As shown, Figure 4 A and Figure 5 A is the TEM image of different positions of the sample. Figure 4 B is Figure 4 A is a local enlarged TEM image. Figure 4 C is Figure 4 Inverse Fourier transform and Fourier transform of B; Figure 5 B is Figure 5 The energy spectrum scan of the white dashed box in A, Figure 5 C is the element distribution diagram. Figure 4 The black block in A is the nano-precipitated phase. After zooming in on the part, we can see Figure 4 B. Figure 4 The red box in B shows the interface between the matrix and the nano-precipitated phase. From the inverse Fourier transform diagram, it can be seen that one side of the nano-precipitated phase is very stable with almost no lattice distortion. Figure 4 The lattice direction index given by the Fourier transform diagram of the green box in B can determine that the nano-precipitated phase is Al2Cu. Figure 5 B is Figure 5 The energy spectrum scan of the white dashed box in A, Figure 5 C is the element distribution diagram. Figure 5 The dark grey part in A (such as the red arrow part) is the nano-precipitated phase in the aluminum-based composite material, and its particle size distribution is 50 to 500 nm. Figure 5 B andFigure 5 As can be seen from C, Figure 5 A The nano-precipitation phase in the dark gray part of the white dotted box is Al2Cu.

[0054] Example 2

[0055] This example provides a method for preparing a heterogeneous aluminum matrix composite material, including the following steps:

[0056] (1) Load the gas atomized spherical aluminum powder (average particle size of 1 μm, purity of 99.9%) and the gas atomized spherical AlLiCu alloy powder (average particle size of 20 μm, purity of 99.9%, the gas atomized spherical AlLiCu alloy powder includes the following components: Al: 95%, Cu: 4%, Li: 1%) into a stainless steel ball milling tank for ball milling and mixing, and fill argon as a protective atmosphere. The rotation speed of the ball mill is 100 r / min, the ball milling time is 12 h, and the ball-to-powder ratio is 3:1 to obtain a composite powder; among them, the mass percentage of the gas atomized spherical AlLiCu alloy powder in the composite powder is 10%.

[0057] (2) Load the composite powder into a graphite mold, and heat it up to 550 °C at a heating rate of 110 °C / min under vacuum for hot pressing and sintering for 0.5 h. The pressure of the hot pressing and sintering is 30 MPa.

[0058] (3) Cool down to 400 °C and hold for 1 h, and then hot roll the material at 400 °C and under vacuum conditions. The rolling reduction is 50%, and the aluminum matrix composite material is obtained.

[0059] Example 3

[0060] This example provides a method for preparing a heterogeneous aluminum matrix composite material, which is different from Example 2 in that:

[0061] In step (1), the average particle size of the gas atomized spherical aluminum powder is 2 μm, the ball-to-powder ratio is 5:1, and the mass percentage of the gas atomized spherical AlLiCu alloy powder in the composite powder is 30%;

[0062] In step (2), the temperature of the hot pressing and sintering is 580 °C;

[0063] In step (3), cool down to 400 °C and hold for 0.5 h.

[0064] Example 4

[0065] This example provides a method for preparing a heterogeneous aluminum matrix composite material, which is different from Example 2 in that:

[0066] In step (1), the ball milling time is 10 h; by mass percentage, the gas atomized spherical AlLiCu alloy powder comprises the following components: Al: 98%, Cu: 1.5%, Li: 0.5%.

[0067] In step (2), the hot pressing sintering temperature is 600 °C.

[0068] In step (3), the rolling reduction is 40%.

[0069] Example 5

[0070] This example provides a method for preparing a heterogeneous configuration aluminum matrix composite material. Different from Example 2:

[0071] In step (1), the average particle size of the gas atomized spherical aluminum powder is 2 μm, the rotation speed of the ball mill is 200 r / min, and the ball milling time is 8 h; the ball-to-powder ratio is 5:1, and the mass percentage of the gas atomized spherical AlLiCu alloy powder in the composite powder is 50%; by mass percentage, the gas atomized spherical AlLiCu alloy powder comprises the following components: Al: 98%, Cu: 1.5%, Li: 0.5%.

[0072] In step (2), the hot pressing sintering time is 1 h.

[0073] Example 6

[0074] This example provides a method for preparing a heterogeneous configuration aluminum matrix composite material. Different from Example 2:

[0075] In step (1), the average particle size of the gas atomized spherical aluminum powder is 3 μm, and the average particle size of the gas atomized spherical AlLiCu alloy powder is 5 μm.

[0076] Through SEM characterization, in the aluminum matrix composite material prepared by the preparation method of the aluminum matrix composite materials in Examples 2 to 6, the average particle size of the matrix Al grains is between 10 and 30 μm, the average particle size of the reinforcing phase AlLiCu alloy grains is between 300 and 500 μm, and there are nano-precipitation phases Al2Cu and Al2CuLi; the particle size distribution of the nano-precipitation phases is 50 to 500 nm; by mass percentage, the AlLiCu alloy grains comprise the following components: Al: 95 - 98%, Cu: 1.5 - 4%, Li: 0.5 - 1%; the mass of the matrix accounts for 50 - 90% of the total mass of the aluminum matrix composite material; the sum of the masses of the reinforcing phase and the nano-precipitation phases accounts for 10 - 50% of the total mass of the aluminum matrix composite material.

[0077] Comparative Example 1

[0078] This comparative example provides a comparative aluminum material. Different from Example 1: It does not contain a reinforcing phase and a nano-precipitation phase.

[0079] This comparative example provides a method for preparing a comparative aluminum material. Different from Example 1:

[0080] In step (1), gas atomized spherical AlLiCu alloy powder is not added.

[0081] Comparative Example 2

[0082] This comparative example provides a comparative aluminum matrix composite material. Different from Example 1: The reinforcing phase is AlLiCu alloy grains with an average particle size of 650 μm.

[0083] This comparative example provides a method for preparing a comparative aluminum matrix composite material. Different from Example 1:

[0084] In step (1), the average particle size of the gas atomized spherical AlLiCu alloy powder is 30 μm.

[0085] Performance Test

[0086] The aluminum matrix composite materials of each example were taken for tests of tensile strength, fracture elongation, density and microhardness. The comparative aluminum material of Comparative Example 1 and the comparative aluminum matrix composite material of Comparative Example 2 were taken for tests of tensile strength and fracture elongation. The test results are shown in Table 1. Among them, the tensile strength and fracture elongation were measured using a universal tensile testing machine (MTS E45.305); the density was measured according to the Archimedes drainage method, and the microhardness was measured using a Vickers hardness tester.

[0087] Table 1 Test results of tensile strength, fracture elongation, density and microhardness

[0088]

[0089]

[0090] As can be seen from Table 1, the tensile strength of the aluminum matrix composites in Examples 1-5 is above 300 MPa, the fracture elongation is above 18%, the relative density is above 99.4%, and the microhardness is above 80 HV, which is greater than that of general aluminum materials (50-60 HV). The tensile strengths of the aluminum matrix composites in Examples 1-5 are all significantly higher than those of the comparative aluminum materials in Comparative Example 1 (without adding AlLiCu alloy powder). For the aluminum matrix composites in Examples 2, 3, and 5, the fracture elongations only decreased by 28%, 24%, and 12% respectively compared with Comparative Example 1; for the aluminum matrix composite in Example 4, the fracture elongation did not decrease compared with Comparative Example 1. In particular, the fracture elongation of the aluminum matrix composite in Example 1 did not decrease compared with Comparative Example 1, but instead increased by 8%. The test results of the aluminum matrix composite in Example 6 are similar to those in Example 2. The above shows that the aluminum matrix composite of the present invention can achieve an increase in tensile strength while the fracture elongation does not decrease significantly, showing good strength-ductility matching, and the aluminum matrix composite has a high relative density and high hardness.

[0091] The average grain size of the AlLiCu alloy grains in the comparative aluminum matrix composite of Comparative Example 2 is too large. Compared with Example 1, both the tensile strength and the fracture elongation are poor; compared with Comparative Example 1, although the tensile strength is increased, the fracture elongation decreases significantly by 56%. The reason is that the too large average grain size of the AlLiCu alloy powder results in too large average grain size of the AlLiCu alloy grains in the prepared comparative aluminum matrix composite, so that a specific fine-coarse grain configuration (heterogeneous configuration) cannot be formed, thereby leading to a significant decrease in the fracture elongation of the comparative aluminum matrix composite.

[0092] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made on the basis of the above description. It is not necessary and impossible to list all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention should be included within the protection scope of the claims of the present invention.

Claims

1. A heterogeneous configuration aluminum matrix composite material, characterized in that, The aluminum matrix composite material comprises a matrix, a reinforcing phase and a nano-precipitation phase; The matrix is composed of Al grains with an average particle size of 10 - 30 μm, the reinforcing phase is composed of AlLiCu alloy grains with an average particle size of 300 - 500 μm, and the nano-precipitation phase is Al2Cu and Al2CuLi.

2. The aluminum matrix composite material according to claim 1, characterized in that, The particle size distribution of the nano-precipitation phase is 50 - 500 nm.

3. The aluminum matrix composite material according to claim 1, characterized in that, By mass percentage, the AlLiCu alloy grains comprise the following components: Al: 95 - 98%, Cu: 1.5 - 4%, Li: 0.5 - 1%.

4. The aluminum matrix composite material according to claim 1, wherein, The mass of the matrix accounts for 50 - 90% of the total mass of the aluminum matrix composite material.

5. The preparation method of the aluminum matrix composite material according to any one of claims 1 to 4, characterized in that, It includes the following steps: Aluminum powder and AlLiCu alloy powder are mixed to obtain a composite powder, and the composite powder is hot-pressed sintered and hot-rolled to obtain the aluminum matrix composite material.

6. The preparation method according to claim 5, characterized in that, The mass percentage of the AlLiCu alloy powder in the composite powder is 10 - 50%.

7. The preparation method according to claim 5, wherein, The average particle size of the AlLiCu alloy powder is 5 - 25 μm.

8. The preparation method according to claim 7, characterized in that, The temperature of the hot-press sintering is 550 - 630 °C.

9. The preparation method according to claim 5, characterized in that The rolling reduction of the hot rolling is 20 - 50%.

10. Use of the aluminum matrix composite material according to any one of claims 1 - 4 in the fields of automobile manufacturing, information communication, aerospace or nuclear power.

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