A lightweight, high-strength, high-modulus Al-Mg based composite material and its preparation method

Abstract

The present invention provides a lightweight, high-strength, high-modulus Al-Mg-based composite material and a preparation method thereof. The Al-Mg-based composite material includes an aluminum matrix and MgAl2O4 particles and AlB2 particles generated by an in-situ reaction; the MgAl2O4 particles are distributed along the grain boundaries of the aluminum matrix; and the AlB2 particles are uniformly distributed on the aluminum matrix. The preparation method is as follows: preparing raw materials according to the following mass percentages: 69.8-91.9% of industrial pure aluminum powder, 6.0-20.0% of Al-50Mg alloy powder, 2.0-10.0% of amorphous boron oxide powder, and 0.1-0.2% of zirconium oxide powder; low-speed ball milling of industrial pure aluminum powder and Al-50Mg alloy powder and high-speed ball milling of amorphous boron oxide powder and zirconium oxide powder; using a cold isostatic press to press the resulting mixture into a preform, and heat-treating it to obtain. The material of the present invention has the advantages of low density, high elastic modulus and strength, and a simple preparation process.

Description

Technical Field

[0001] The present invention belongs to the field of metal matrix composite materials, and in particular relates to a lightweight, high-strength, high-modulus Al-Mg matrix composite material and a preparation method thereof. Background Art

[0002] Al-Mg-based alloys have been widely used in the fields of shipbuilding, automobiles, and 3C due to their excellent properties such as light weight and corrosion resistance. However, with the increasingly stringent requirements for energy conservation and emission reduction, various industries have higher and higher requirements for the performance of aluminum alloys. Compared with the use of alloying elements to improve alloy properties, particle-reinforced Al-Mg-based composites provide a new way to expand the application of aluminum alloys due to their strong microstructure designability and the advantages of both aluminum matrix and reinforcing particles. However, traditional reinforcing particles (such as TiC, SiC, etc.) are very likely to react with the Al-Mg matrix to produce harmful interfacial reactions, thereby damaging the plasticity and toughness of the material. On the other hand, they will significantly reduce the corrosion resistance of the alloy.

[0003] MgAl2O4 has advantages such as a high melting point (2135°C), high hardness (16 GPa), high elastic modulus (273 GPa), strong chemical corrosion resistance, high resistivity, and low thermal expansion coefficient. Theoretically, it can serve as an excellent reinforcement for Al-Mg-based alloys. Reference [Measurement, 2018, 129:389-394] prepared a MgAl2O4-reinforced Al-Mg-based composite by adding H3BO3 to an Al-4Mg melt. Ultrasonic treatment significantly refined the grain size of the solidified material. Reference [Journal of Alloys and Compounds, 2022, 891:161991] prepared a MgAl2O4-reinforced Al-Mg-Zn composite in an Al-3Mg-7ZnO system, demonstrating excellent tensile strength. However, the above method still has the following problems: on the one hand, since the Mg element is extremely volatile in the aluminum melt and the vapor pressure of Mg is relatively high, the Mg content in the composite materials prepared by this method is greatly limited, and its mass fraction is usually not higher than 5%, which limits the designability of the comprehensive performance of the material; on the other hand, the material preparation process requires complex processes such as ultrasonic treatment to improve the dispersibility of MgAl2O4, which makes the material preparation process complicated and the cost increased; on the other hand, the in situ synthesized MgAl2O4 is usually micron particles or whiskers. Compared with nanoparticles, the micron-scale reinforcement has limited strengthening effect and the whiskers are anisotropic, which affects the uniformity of the material structure and performance; on the other hand, the distribution of MgAl2O4 is difficult to control, and it is usually in the form of aggregated clusters or random distribution, which significantly weakens the strengthening effect and greatly limits the application of MgAl2O4 in Al-Mg based composites.

[0004] Therefore, it is of great significance to develop a lightweight, high-strength, high-modulus MgAl2O4 reinforced Al-Mg based composite material with low cost and simple preparation process. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention provides a lightweight, high-strength, high-modulus Al-Mg-based composite material and its preparation method. The present invention utilizes an in-situ reaction to generate MgAl2O4 and AlB2 particles for synergistic reinforcement of the Al-Mg-based composite material, resulting in a material with low density, high elastic modulus, and high strength. Furthermore, the present invention's preparation method is cost-effective and simple.

[0006] The present invention is achieved in the following ways:

[0007] A lightweight, high-strength, high-modulus Al-Mg-based composite material comprises an aluminum matrix and MgAl2O4 particles and AlB2 particles generated by an in-situ reaction; the mass percentage of the MgAl2O4 particles is 3.0-15.2%, and the MgAl2O4 particles are distributed along the grain boundaries of the aluminum matrix grains; the mass percentage of the AlB2 particles is 1.4-7.0%, and the AlB2 particles are uniformly distributed on the aluminum matrix; the Mg content is 0.4-9.5%, and the AlB2 particles are solid dissolved in the aluminum matrix.

[0008] Preferably, according to the present invention, the size of the MgAl2O4 particles is 10 to 100 nm; the size of the AlB2 particles is 0.2 to 2 μm.

[0009] According to the preferred embodiment of the present invention, the grain size of the aluminum matrix is ​​1 to 20 μm.

[0010] According to the present invention, the lightweight, high-strength, high-modulus Al-Mg-based composite material further contains 0.07-0.15% by mass of zirconium, which is solid-dissolved in the aluminum matrix.

[0011] According to the present invention, the method for preparing the above-mentioned lightweight, high-strength and high-modulus Al-Mg based composite material comprises the following steps:

[0012] (1) Prepare the required raw materials according to the following mass percentages: 69.8-91.9% of industrial pure aluminum powder, 6.0-20.0% of Al-50Mg alloy powder, 2.0-10.0% of amorphous boron oxide powder, and 0.1-0.2% of zirconium oxide powder;

[0013] (2) ball milling the industrial pure aluminum powder and Al-50Mg alloy powder in step (1) at a low speed under an argon atmosphere to obtain a material;

[0014] (3) mixing the material obtained by ball milling in step (2) with amorphous boron oxide powder and zirconium oxide powder, and ball milling at high speed under an argon atmosphere to obtain a mixed material;

[0015] (4) pressing the mixed material obtained by ball milling in step (3) into a preform using a cold isostatic press; then placing the preform in a vacuum furnace for heat treatment to obtain a lightweight, high-strength, and high-modulus Al-Mg-based composite material.

[0016] According to the preferred embodiment of the present invention, the size of the industrial pure aluminum powder in step (1) is ≤50 μm, more preferably 1-20 μm; the size of the Al-50Mg alloy powder is ≤150 μm, more preferably 10-100 μm; the size of the amorphous boron oxide powder is ≤5 μm; and the size of the zirconium oxide powder is ≤5 μm.

[0017] According to the preferred embodiment of the present invention, the rotation speed of the low-speed ball mill in step (2) is ≤150 r / min, more preferably 50-150 r / min; the time of the low-speed ball mill is 1-3 h, and the ball-to-material ratio of the low-speed ball mill is 5-8:1.

[0018] According to the preferred embodiment of the present invention, the rotation speed of the high-speed ball mill in step (3) is ≥350 r / min, more preferably 350-480 r / min; the time of the high-speed ball mill is 2-6 h, and the ball-to-material ratio of the high-speed ball mill is 3-10:1.

[0019] Preferably, according to the present invention, in step (4), the pressure of the cold isostatic press is 100 to 300 MPa, and the holding time is 5 to 30 minutes.

[0020] According to the preferred embodiment of the present invention, the heat treatment temperature in step (4) is 500-720°C, the heat treatment time is 30-150 min, and the heat treatment is carried out at a vacuum degree of 1×10 -5 ~1×10 -2 Paozhong carried out.

[0021] The technical features and beneficial effects of the present invention are as follows:

[0022] 1. The MgAl2O4 and AlB2 particles in the lightweight, high-strength, and high-modulus Al-Mg based composite material obtained by the present invention synergistically enhance the material performance. The present invention generates MgAl2O4 and AlB2 particles in the Al-Mg matrix through the in-situ endogenous principle. The size of the MgAl2O4 particles is 10 to 100 nm, and the size of the AlB2 particles is 0.2 to 2 μm. The two have strong interface bonding with the matrix and good stability, which significantly enhances the performance of the Al-Mg based composite material.

[0023] 2. The composite material preparation process of the present invention includes two ball milling steps. In the first ball milling step, aluminum powder and Al-50Mg powder are ball milled at a low speed to ensure uniform mixing of the raw materials and avoid the risk of increased Mg activity due to excessive heat generated during ball milling, thereby improving the safety of the material preparation process. In the second ball milling step, amorphous boron oxide powder is fully encapsulated around the aluminum powder and Al-50Mg powder and crystallized by the heat generated during the ball milling process, thereby ensuring the controlled progress of subsequent reactions. Compared to industrial Mg powder, the aforementioned characteristics of Al-50Mg powder significantly expand the range of Mg content in the composite material. In the composite material of the present invention, the Mg content can be controlled within a range of 0.4 to 9.5%, providing a guarantee for the design and regulation of the material's comprehensive performance. In addition, the presence of zirconium oxide, a growth inhibitor, limits the growth of MgAl2O4 particles formed by the in-situ reaction. The resulting nanosized particles are distributed along the grain boundaries of the aluminum matrix, exerting a synergistic strengthening effect with the uniformly distributed AlB2 particles.

[0024] 3. The Al-Mg based composite material of the present invention has the performance characteristics of light weight, high strength and high modulus, and its density is 2.45-2.70 g / cm 3 The room temperature strength can reach 550MPa, and the elastic modulus can reach more than 90GPa. It can be used in the production of parts in the fields of automobiles, aerospace, rail transportation, etc.

[0025] 4. The present invention's method for preparing the Al-Mg-based composite material is simple. By controlling the raw material ratio, ball milling rate and time, and reaction temperature and time, the size and distribution of the reinforcing phase can be controlled, thereby enabling the design and regulation of the comprehensive properties of the Al-Mg-based composite material. The present method utilizes low-cost materials, a simple process, and an environmentally friendly preparation method, making it suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a transmission electron microscope photograph of the lightweight, high-strength, high-modulus Al-Mg based composite material prepared in Example 1; in the figure, 1 is AlB2 particles, 2 is aluminum matrix grains, and 3 is MgAl2O4 particles.

[0027] Figure 2 These are the transmission electron microscope photos (BF), HAADF images and surface scanning pictures of the lightweight, high-strength and high-modulus Al-Mg based composite material prepared in Example 1. DETAILED DESCRIPTION

[0028] The present invention will be further described below with reference to specific embodiments, but is not limited thereto.

[0029] Meanwhile, the experimental methods described in the following examples, unless otherwise specified, are conventional methods; the reagents, materials and equipment, unless otherwise specified, can be obtained from commercial channels.

[0030] Example 1

[0031] A method for preparing a lightweight, high-strength, high-modulus Al-Mg based composite material comprises the following steps:

[0032] (1) Prepare the required raw materials according to the following mass percentages: 83.9% of industrial pure aluminum powder (size 1 μm), 6.0% of Al-50Mg alloy powder (size 10 μm), 10.0% of amorphous boron oxide powder (size 5 μm), and 0.1% of growth inhibitor zirconium oxide powder (size 1 μm);

[0033] (2) placing the industrial pure aluminum powder and Al-50Mg alloy powder in step (1) into a ball mill and milling at a low speed for 3 h. The ball milling was carried out under an argon atmosphere with a ball-to-material ratio of 8:1 and a ball mill speed of 150 r / min to obtain the material;

[0034] (3) The material obtained by ball milling in step (2) was mixed with amorphous boron oxide powder and zirconium oxide powder, and then high-speed ball milling was performed for 6 hours. The ball milling was carried out under an argon atmosphere with a ball-to-material ratio of 10:1 and a ball mill speed of 480 r / min to obtain a mixed material;

[0035] (4) pressing the mixed material obtained by ball milling in step (3) into a preform using a cold isostatic press at a pressure of 300 MPa for 30 min;

[0036] (5) Place the preform in a vacuum furnace and heat it. Set the vacuum degree to 1×10 -5 Pa, control temperature is 720℃, and holding time is 150min.

[0037] According to the above-mentioned ratio and process, a lightweight, high-strength and high-modulus Al-Mg based composite material synergistically reinforced by MgAl2O4 and AlB2 particles can be obtained, whose composition (mass percentage) is Al-0.4Mg-15.2MgAl2O4-7AlB2, that is, the composite material includes MgAl2O4 particles with a mass fraction of 15.2%, AlB2 particles with a mass fraction of 7.0%, and Mg with a mass fraction of 0.4%, and Mg is solid-dissolved in the aluminum matrix; the Al-Mg based composite material also includes 0.07% zirconium solid-dissolved in the aluminum matrix, and its content is included in the aluminum matrix.

[0038] The density of the Al-Mg based composite material obtained in this example is 2.70 g / cm 3 , the room temperature strength is 550MPa and the elastic modulus is 92GPa.

[0039] Figure 1 Transmission electron microscope photos of lightweight, high-strength and high-modulus Al-Mg based composite materials prepared in this example. Figure 1 It can be seen that the grain size of the composite material is submicron, submicron AlB2 particles are dispersed between the grains, and nano-sized MgAl2O4 particles are distributed at the grain boundaries.

[0040] Figure 2 The transmission electron microscope photos, HAADF images and surface scanning images of a typical area of ​​the lightweight, high-strength and high-modulus Al-Mg based composite material prepared in this embodiment are as follows: Figure 2 It can be seen that the particle sizes of MgAl2O4 and AlB2 are approximately 80 nm and 0.2 μm, respectively.

[0041] Example 2

[0042] A method for preparing a lightweight, high-strength, high-modulus Al-Mg based composite material comprises the following steps:

[0043] (1) Prepare the required raw materials in the following mass percentages: 77.8% of industrial pure aluminum powder (size 20 μm), 20.0% of Al-50Mg alloy powder (size 40 μm), 2.0% of amorphous boron oxide powder (size 1 μm), and 0.2% of growth inhibitor zirconium oxide powder (size 2 μm);

[0044] (2) placing the industrial pure aluminum powder and Al-50Mg alloy powder in step (1) into a ball mill and milling at a low speed for 1 h. The ball milling was carried out under an argon atmosphere with a ball-to-material ratio of 5:1 and a ball mill speed of 50 r / min to obtain the material;

[0045] (3) The material obtained by ball milling in step (2) was mixed with amorphous boron oxide powder and zirconium oxide powder, and then high-speed ball milling was performed for 2 h. The ball milling was carried out under an argon atmosphere with a ball-to-material ratio of 3:1 and a ball mill speed of 350 r / min to obtain a mixed material;

[0046] (4) pressing the mixed material obtained by ball milling in step (3) into a preform using a cold isostatic press at a pressure of 100 MPa for 5 min;

[0047] (5) Place the preform in a vacuum furnace and heat it. Set the vacuum degree to 1×10 -2 Pa, control temperature to 560℃, and hold time to 30min.

[0048] According to the above ratio and process, a lightweight, high-strength and high-modulus Al-Mg based composite material synergistically reinforced by MgAl2O4 and AlB2 particles can be obtained, and its composition (mass percentage) is: Al-9.5Mg-3MgAl2O4-1.4AlB2, that is, the composite material includes MgAl2O4 particles with a mass fraction of 3.0%, AlB2 particles with a mass fraction of 1.4%, and Mg with a mass fraction of 9.5%, and Mg is solid-dissolved in the aluminum matrix; the Al-Mg based composite material also includes 0.15% zirconium solid-dissolved in the aluminum matrix, and its content is counted into the aluminum matrix.

[0049] The density of the Al-Mg based composite material obtained in this example is 2.45 g / cm 3 , the room temperature strength is 455MPa and the elastic modulus is 75GPa.

[0050] Example 3

[0051] A method for preparing a lightweight, high-strength, high-modulus Al-Mg based composite material comprises the following steps:

[0052] (1) Prepare the required raw materials according to the following mass percentages: 79.9% of industrial pure aluminum powder (size 10 μm), 15.0% of Al-50Mg alloy powder (size 100 μm), 5.0% of amorphous boron oxide powder (size 2 μm), and 0.1% of growth inhibitor zirconium oxide powder (size 2 μm);

[0053] (2) placing the industrial pure aluminum powder and Al-50Mg alloy powder in step (1) into a ball mill and milling at a low speed for 2 h. The ball milling was carried out under an argon atmosphere with a ball-to-material ratio of 7:1 and a ball mill speed of 100 r / min to obtain the material;

[0054] (3) The material obtained by ball milling in step (2) was mixed with amorphous boron oxide powder and zirconium oxide powder, and then high-speed ball milled for 3 hours. The ball milling was carried out under an argon atmosphere with a ball-to-material ratio of 8:1 and a ball mill speed of 400 r / min to obtain a mixed material;

[0055] (4) pressing the mixed material obtained by ball milling in step (3) into a preform using a cold isostatic press at a pressure of 200 MPa for 15 min;

[0056] (5) Place the preform in a vacuum furnace and heat it. Set the vacuum degree to 1×10 -3 Pa, control temperature is 680℃, and holding time is 60min.

[0057] According to the above ratio and process, a lightweight, high-strength and high-modulus Al-Mg based composite material synergistically reinforced by MgAl2O4 and AlB2 particles can be obtained, and its composition (mass percentage) is: Al-6.2Mg-7.6MgAl2O4-3.5AlB2, that is, the composite material includes MgAl2O4 particles with a mass fraction of 7.6%, AlB2 particles with a mass fraction of 3.5%, and Mg with a mass fraction of 6.2%, and Mg is solid-dissolved in the aluminum matrix; the Al-Mg based composite material also includes 0.07% zirconium solid-dissolved in the aluminum matrix, and its content is counted into the aluminum matrix.

[0058] The density of the Al-Mg based composite material obtained in this example is 2.63 g / cm 3 , the room temperature strength is 505MPa and the elastic modulus is 84GPa.

Claims

1. A lightweight, high-strength, high-modulus Al-Mg based composite material, characterized in that: The lightweight, high-strength, high-modulus Al-Mg-based composite material includes an aluminum matrix and MgAl2O4 particles and AlB2 particles generated by an in-situ reaction; the mass percentage of the MgAl2O4 particles is 3.0-15.2%, and the MgAl2O4 particles are distributed along the grain boundaries of the aluminum matrix grains; the mass percentage of the AlB2 particles is 1.4-7.0%, and the AlB2 particles are uniformly distributed on the aluminum matrix; the mass fraction of Mg is 0.4-9.5%, and the AlB2 particles are solid dissolved in the aluminum matrix.

2. The lightweight, high-strength, high-modulus Al-Mg based composite material according to claim 1, characterized in that: The size of the MgAl2O4 particles is 10-100 nm; the size of the AlB2 particles is 0.2-2 μm.

3. The lightweight, high-strength, high-modulus Al-Mg based composite material according to claim 1, characterized in that: The grain size of the aluminum matrix is ​​1-20 μm.

4. The method for preparing the lightweight, high-strength, high-modulus Al-Mg based composite material according to claim 1, comprising the following steps: (1) Prepare the required raw materials according to the following mass percentages: industrial pure aluminum powder 69.8~91.9%, Al-50Mg alloy powder 6.0~20.0%, amorphous boron oxide powder 2.0~10.0%, zirconium oxide powder 0.1~0.2%; (2) ball milling the industrial pure aluminum powder and Al-50Mg alloy powder in step (1) at a low speed under an argon atmosphere to obtain a material; (3) mixing the material obtained by ball milling in step (2) with amorphous boron oxide powder and zirconium oxide powder, and performing high-speed ball milling under an argon atmosphere to obtain a mixed material; (4) The mixed material obtained by ball milling in step (3) is pressed into a preform using a cold isostatic press; the preform is then placed in a vacuum furnace for heat treatment to obtain a lightweight, high-strength, and high-modulus Al-Mg based composite material.

5. The method for preparing a lightweight, high-strength, high-modulus Al-Mg based composite material according to claim 4, characterized in that: The size of the industrial pure aluminum powder in step (1) is ≤50 μm; the size of the Al-50Mg alloy powder is ≤150 μm; the size of the amorphous boron oxide powder is ≤5 μm; and the size of the zirconium oxide powder is ≤5 μm.

6. The method for preparing a lightweight, high-strength, high-modulus Al-Mg based composite material according to claim 4, characterized in that: The size of the industrial pure aluminum powder in step (1) is 1-20 μm; the size of the Al-50Mg alloy powder is 10-100 μm.

7. The method for preparing a lightweight, high-strength, high-modulus Al-Mg based composite material according to claim 4, characterized in that: The rotation speed of the low-speed ball mill in step (2) is ≤150 r / min; the time of the low-speed ball mill is 1 to 3 hours, and the ball-to-material ratio of the low-speed ball mill is 5 to 8:

1.

8. The method for preparing a lightweight, high-strength, high-modulus Al-Mg based composite material according to claim 4, characterized in that: The rotation speed of the low-speed ball mill in step (2) is 50-150 r / min.

9. The method for preparing a lightweight, high-strength, high-modulus Al-Mg based composite material according to claim 4, characterized in that: The rotation speed of the high-speed ball mill in step (3) is ≥350 r / min; the time of the high-speed ball mill is 2 to 6 hours, and the ball-to-material ratio of the high-speed ball mill is 3 to 10:

1.

10. The method for preparing a lightweight, high-strength, high-modulus Al-Mg based composite material according to claim 4, characterized in that: The rotation speed of the high-speed ball mill in step (3) is 350~480r / min.

11. The method for preparing a lightweight, high-strength, high-modulus Al-Mg based composite material according to claim 4, characterized in that: In step (4), the pressure of the cold isostatic press is 100-300 MPa, and the holding time is 5-30 min.

12. The method for preparing a lightweight, high-strength, high-modulus Al-Mg based composite material according to claim 4, characterized in that: The heat treatment temperature in step (4) is 500-720°C, the heat treatment time is 30-150 min, and the heat treatment is carried out in a vacuum of 1×10 -5 ~1×10 -2 Paozhong carried out.

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