Preparation method of in-situ endogenous multiphase particle reinforced aluminum-based composite material

Abstract

The invention discloses a preparation method of an in-situ endogenous multiphase particle reinforced aluminum-based composite material, and belongs to the field of metal-based composite materials. The aluminum-based composite material is characterized in that in-situ generated nano Al2O3 particles and micron (Al, Si, Ti) ternary intermetallic compound particles are uniformly distributed on an aluminum-silicon alloy matrix; the preparation method comprises the following steps: carrying out variable-speed ball milling on raw materials in an argon environment, pressing in a cold / hot isostatic press to obtain a prefabricated blank, sintering the prefabricated blank, and carrying out hot extrusion to obtain the Al2O3 and (Al, Si and Ti) ternary intermetallic compound multiphase reinforced aluminum alloy-based composite material. According to the aluminum-based composite material provided by the invention, nano Al2O3 and micron (Al, Si and Ti) ternary intermetallic compound particles are well combined with a matrix interface, and the strength, modulus and wear resistance of the material are improved through the cooperation of the two micro-nano particles.

Description

Technical Field

[0001] The invention belongs to the field of metal matrix composite materials, and in particular relates to a method for preparing an in-situ endogenous multiphase particle reinforced aluminum matrix composite material. Background Art

[0002] Aluminum-silicon alloys are often used for manufacturing pistons, cylinder liners, pulleys, transmissions and other parts of automobile or motorcycle engines due to their good wear resistance, low thermal expansion coefficient and density that is only one-third of that of steel. They can also be used in aerospace, transportation, electrical engineering and many other fields. However, with the rapid development of industry, aluminum-silicon alloys have poor high-temperature tensile strength, and their tensile strength at a service temperature of 350°C is less than 100MPa.

[0003] In order to improve the high-temperature performance of aluminum-silicon alloys, particle-reinforced aluminum-based composites have received increasing attention; ceramic particles have high melting point and high strength, and have better strengthening effects than alloying elements; at present, the common preparation method of particle-reinforced aluminum-based composites often uses the external addition method, but there is a problem of poor wettability at the interface between the reinforcement particles and the matrix; the composite materials prepared by the in-situ endogenous method have high bonding strength between the reinforcement particles and the matrix interface, which can better improve the performance of the material compared to the external addition method; alumina has excellent properties such as low density and high melting point, which can significantly improve the high-temperature performance of the material; at the same time, the introduction of Ti elements can form (Al, Si, Ti) ternary metal compounds, which have good properties such as good high temperature resistance and high volume stability. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and propose an Al-Si based composite material with in-situ endogenous nano-Al2O3 particles and micron (Al, Si, Ti) ternary metal compound particles multiphase reinforced. The composite material has the characteristics of good dispersion of reinforced particles, high strength, good wear resistance and other good comprehensive properties.

[0005] Another object of the present invention is to provide a method for preparing the aluminum-based composite material, which specifically comprises the following steps:

[0006] (1) Al-Si powder and TiO2 powder are evenly dispersed by low-speed ball milling in an argon environment, and then activated by high-speed ball milling.

[0007] (2) The TiO2 / Al-Si mixed powder is pressed into a preform on a cold / hot isostatic press.

[0008] (3) The obtained TiO2 / Al-Si preform is placed in a sintering furnace for sintering, and then hot-extruded to obtain a composite material.

[0009] As a preferred embodiment of the present invention, the particle size of the TiO2 powder used is 2-5 μm, and the mass percentage of silicon in the Al-Si powder is 10%-15%.

[0010] As a preferred embodiment of the present invention, in step (1), the low-speed ball milling speed is 150-200 rpm, the time is 2-6 hours, and the ball-to-material ratio is 10:1; the high-speed ball milling speed is 300-400 rpm, the time is 4-8 hours, and the ball-to-material ratio is 10:1.

[0011] As a preferred embodiment of the present invention, the pressure used for pressing the green body in step (2) is 600-700 MPa and the time is 20-30 min.

[0012] As a preferred embodiment of the present invention, the mass percentage of titanium dioxide in the composite material is 1%-9%.

[0013] As a preferred embodiment of the present invention, the sintering temperature is 650° C.-750° C., the holding time is 40-120 min for sintering, and high-purity argon gas (gas flow rate is 80-100 mL / min) is introduced for atmosphere protection.

[0014] As a preferred embodiment of the present invention, the hot extrusion temperature is 460-500°C, the holding time is 1h, and the extrusion ratio is 25:1.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) Variable-speed ball milling can effectively regulate the unit morphology of Al-Si powder and the dispersion effect of TiO2 powder. During low-speed ball milling, the main force between the steel ball and the TiO2 / Al-Si mixed powder is shear force, which can effectively promote the dispersion of TiO2. At the same time, the Al-Si powder is flaked, providing a larger surface for the uniform dispersion of TiO2. In the subsequent high-speed ball milling, the main force between the steel ball and the TiO2 / Al-Si flaky mixed powder is radial pressure, which is beneficial to improve the interface bonding between the flaky powders and promote the in-situ reaction between TiO2 and Al-Si.

[0017] (2) Compared with external reinforcements, in-situ self-generated nano-scale alumina particles and micron-scale (Al, Si, Ti) ternary metal compound particles have the characteristics of uniform distribution in the matrix and better interface bonding; micron-scale particles can improve the strength and modulus of the matrix, but strength and plasticity are usually inversely proportional, and the improvement in high-temperature stability is not obvious; the reinforcing phase strengthening effect of nanoparticles is significantly better than that of micron-scale particles, and can significantly improve the strength and plasticity of materials, which is the focus of research on metal matrix composites. However, nanoparticles have the characteristics of high surface energy and large specific surface area, and are prone to agglomeration in the matrix, and it is difficult to prepare high volume fraction nanoparticle-reinforced metal matrix composites; therefore, through reasonable component design and appropriate preparation process, the micro / nano dual-scale particles are combined to strengthen Al-based composites, which can give play to the advantages of different scales to a certain extent, and the dual-scale reinforcing phases can also complement each other and synergistically strengthen the Al-based composites, which is beneficial to improve the strength and modulus of the material and to a certain extent improve the plasticity of the material.

[0018] (3) By controlling the ratio of Al-Si powder to TiO2 powder in the composite material, the content of the reinforcement generated by the reaction can be controlled, and the size and morphology of the reinforcement particles can be controlled by the reaction temperature and insulation time. Increasing the reaction temperature and extending the insulation time can increase the size of the Al2O3 and (Al, Si, Ti) ternary metal compound particles.

[0019] The in-situ self-generated alumina particles and (Al, Si, Ti) ternary metal compound particles in the composite material prepared by the present invention are thermodynamically stable and have a clean and pollution-free surface. The endogenous reinforcement has a high bonding strength with the matrix, is evenly distributed, has no agglomeration phenomenon, and shows a directional arrangement trend after hot extrusion. The micro-nanoscale reinforcement has a synergistic strengthening effect, exhibits good mechanical properties, high wear resistance, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is the SEM photo of Example 1;

[0021] Figure 2 This is the SEM photo of Example 2;

[0022] Figure 3 This is the SEM photo of Example 3;

[0023] Figure 4 Stress-strain curves of the prepared composite materials. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the described contents.

[0025] Example 1

[0026] (1) Al12Si powder and titanium dioxide powder were weighed in a ratio of 95:5, and were first ball-milled at a low speed of 200 r / min for 4 h; then at a high speed of 400 r / min for 6 h; the above variable speed ball milling was carried out in a high-purity argon atmosphere, and the ball-to-material ratio was set to 10:1.

[0027] (2) The composite powder obtained by variable speed ball milling in step (1) is cold pressed under a hydraulic press at a pressure of 600 MPa for 30 minutes to form a preform.

[0028] (3) The preform obtained in step (2) is placed in a tubular furnace and high-purity argon gas (gas flow rate is 80 mL / min) is introduced for atmosphere protection sintering. The sintering temperature is controlled at 650° C. and the sintering holding time is 40 min to obtain a sintered green body.

[0029] (4) The sintered green body obtained in step (3) is hot extruded at 490°C in a ratio of 25:1 to obtain an Al2O3 particle and (Al, Si, Ti) ternary intermetallic compound particle reinforced aluminum-silicon based composite material having a tensile strength of 329 MPa and an elongation of 7.5%.

[0030] The SEM photo of the composite material prepared in this example is as follows Figure 1 As shown, it can be seen from the figure that the in-situ self-generated light gray nano-alumina particles and gray micron (Al, Si, Ti) ternary metal compound particles.

[0031] Example 2

[0032] (1) Al15Si powder and titanium dioxide powder were weighed in a ratio of 99:1, and the mixture was ball-milled at a low speed for 2 h at a speed of 150 r / min; then ball-milled at a high speed for 8 h at a speed of 350 r / min. The above variable-speed ball milling was carried out in a high-purity argon atmosphere, and the ball-to-material ratio was set to 10:1.

[0033] (2) The composite powder obtained by variable speed ball milling in step (1) is cold pressed for 25 minutes under a hydraulic press at a pressure of 650 MPa to form a preform.

[0034] (3) The preform obtained in step (2) is placed in a tubular furnace and high-purity argon gas (gas flow rate is 80 mL / min) is introduced for atmosphere protection sintering. The sintering temperature is controlled at 700° C. and the sintering holding time is 90 min to obtain a sintered green body.

[0035] (4) The sintered green body obtained in step (3) is hot extruded at 500° C. in a ratio of 25:1 to obtain an aluminum-silicon-based composite material reinforced with Al2O3 particles and (Al, Si, Ti) ternary intermetallic compound particles, the mechanical properties of which include a tensile strength of 300 MPa and an elongation of 7%.

[0036] The SEM photo of the composite material prepared in this example is as follows Figure 2 As shown in the figure, it can be seen that the in-situ self-generated light gray nano-alumina particles and gray micron (Al, Si, Ti) ternary metal compound particles are obviously oriented and distributed along the extrusion direction.

[0037] Example 3

[0038] (1) Al12Si powder and titanium dioxide powder were weighed in a ratio of 91:9, and the powders were ball-milled at low speed for 6 h at a speed of 200 r / min; then ball-milled at high speed for 4 h at a speed of 300 r / min; the above variable speed ball milling was carried out in a high-purity argon atmosphere, and the ball-to-material ratio was set to 10:1.

[0039] (2) The composite powder obtained by variable speed ball milling in step (1) is cold pressed under a hydraulic press at a pressure of 700 MPa for 20 minutes to form a preform.

[0040] (3) The preform obtained in step (2) is placed in a tubular furnace and high-purity argon gas (gas flow rate is 80 mL / min) is introduced for atmosphere protection sintering. The sintering temperature is controlled at 750° C. and the sintering holding time is 120 min to obtain a sintered green body.

[0041] (4) The sintered green body obtained in step (3) is hot extruded at 460°C in a ratio of 25:1 to obtain an Al2O3 particle and (Al, Si, Ti) ternary intermetallic compound particle reinforced aluminum-silicon based composite material, the mechanical properties of which include a tensile strength of 225 MPa and an elongation of 8%.

[0042] The SEM photo of the composite material prepared in this example is as follows Figure 3 As shown, it can be seen from the figure that the in-situ self-generated light gray nano-alumina particles and gray micron (Al, Si, Ti) ternary metal compound particles are significantly larger than the alumina particles and (Al, Si, Ti) ternary metal compound particles generated in Examples 1 and 2.

[0043] Comparative Example 1

[0044] (1) Weigh Al12Si powder and mill it at a low speed of 200 r / min for 4 h; then mill it at a high speed of 400 r / min for 6 h; the above variable speed ball milling is carried out under a high-purity argon atmosphere, and the ball-to-material ratio is set to 10:1.

[0045] (2) The composite powder obtained by variable speed ball milling in step (1) is cold pressed under a hydraulic press at a pressure of 600 MPa for 30 minutes to form a preform.

[0046] (3) The preform obtained in step (2) is placed in a tubular furnace and high-purity argon gas (gas flow rate is 80 mL / min) is introduced for atmosphere protection sintering. The sintering temperature is controlled at 650° C. and the sintering holding time is 60 min to obtain a sintered green body.

[0047] (4) The sintered green body obtained in step (3) is hot extruded at 490° C. in a ratio of 25:1 to obtain an Al12Si composite material having mechanical properties of a tensile strength of 150 MPa and an elongation of 10%.

[0048] By comparison, it can be seen that the addition of titanium oxide in situ generates nano-alumina particles mixed with micron (Al, Si, Ti) ternary metal compound particles to improve the mechanical properties of the material. Common powder metallurgy preparation of composite materials uses external reinforcement particles to improve material performance, but due to the poor bonding at the matrix interface and the difficulty in dispersing nanoparticles, the performance improvement is small; in-situ self-generated reinforcement can solve the above problems and fully improve the performance of the material.

[0049] According to the above-mentioned ratio and sintering process, an in-situ self-generated Al2O3 particle and (Al, Si, Ti) ternary metal compound particle reinforced aluminum-silicon based composite material can be obtained. In the composite material prepared by the present invention, the multiphase particles Al2O3 particles and (Al, Si, Ti) ternary metal compound particles are well bonded to the matrix Al-Si interface, the reinforcement particles are evenly distributed, and the two micro-nano-scale particles synergistically improve the strength and wear resistance of the material.

Claims

1. A method for preparing an in-situ endogenous multiphase particle reinforced aluminum matrix composite material, characterized in that: The specific steps include: (1) The Al-Si powder and the TiO2 powder are uniformly dispersed by low-speed ball milling in an argon environment, and then the powders are activated by high-speed ball milling; (2) pressing the TiO2 / Al-Si mixed powder into a preform on a cold / hot isostatic press; (3) The obtained TiO2 / Al-Si preform is placed in a sintering furnace for sintering, and then hot-extruded to obtain a composite material.

2. The method for preparing an in-situ endogenous multiphase particle reinforced aluminum matrix composite material according to claim 1, characterized in that: The particle size of the TiO2 powder used is 2-5 μm, and the mass percentage of silicon in the Al-Si powder is 10%-15%.

3. The method for preparing an in-situ endogenous multiphase particle reinforced aluminum matrix composite material according to claim 1, characterized in that: In the step (1), the low-speed ball milling speed is 150-200 rpm, the time is 2-6 hours, and the ball-to-material ratio is 10:

1.

4. The method for preparing an in-situ endogenous multiphase particle reinforced aluminum matrix composite material according to claim 1, characterized in that: In the step (1), the high-speed ball milling speed is 300-400 rpm, the time is 4-8 hours, and the ball-to-material ratio is 10:

1.

5. The method for preparing an in-situ endogenous multiphase particle reinforced aluminum matrix composite material according to claim 1, characterized in that: The pressure used for pressing the green body in step (2) is 600-700 MPa and the time is 20-30 min.

6. The method for preparing an in-situ endogenous multiphase particle reinforced aluminum matrix composite material according to claim 1, characterized in that: The mass percentage of titanium dioxide in the TiO2 / Al-Si mixed powder is 1%-9%.

7. The method for preparing an in-situ endogenous multiphase particle reinforced aluminum matrix composite material according to claim 1, characterized in that: The sintering temperature is 650° C.-750° C., the heat preservation time is 40-120 minutes for sintering, and protective gas is introduced for atmosphere protection.

8. The method for preparing an in-situ endogenous multiphase particle reinforced aluminum matrix composite material according to claim 7, characterized in that: The protective gas is argon, and the gas flow rate is 80-100 mL / min.

9. The method for preparing an in-situ endogenous multiphase particle reinforced aluminum matrix composite material according to claim 1, characterized in that: The hot extrusion temperature is 460-500° C., the holding time is 1 hour, and the extrusion ratio is 25:1.

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