A method for preparing a high-strength carbon nanotube reinforced aluminum matrix composite ring-shaped special-shaped part

Abstract

The application discloses a kind of preparation methods of high-strength carbon nanotube reinforced aluminum matrix composite ring-shaped special-shaped parts, belong to aluminum matrix composite technical field.The method is with CNT reinforced aluminum matrix composite ring blank as raw material, by adjusting ring rolling temperature to moderate interval (100 to 200 DEG C lower than solid solution temperature), so that CNT can be arranged along the ring rolling direction, promote load transfer strengthening efficiency to give full play to;At the same time, high-density dislocation is induced near the grain boundary, provides nucleation sites for precipitated phase, reduces the content of non-precipitated zone after aging, so that the material can have very high strength level.The orientation of precipitated phase and reinforcing phase of composite material is coupled and regulated by plastic processing, and the controllability is strong, and the controllability of organization is higher.

Description

Technical Field

[0001] This invention relates to the field of aluminum-based composite materials technology, and specifically to a method for preparing a high-strength carbon nanotube-reinforced aluminum-based composite ring-shaped part. Background Technology

[0002] Irregularly shaped ring components are widely used in engineering applications, especially in ring-shaped support structures in the aerospace field. As key load-bearing components, they not only require high strength along the circumference but also need to be as lightweight as possible while maintaining safe service life to achieve energy conservation and efficiency. High-strength aluminum alloys, represented by Al-Cu and Al-Zn-Mg-Cu systems, are widely used in the aerospace field, but their application in critical load-bearing structures is still limited because their absolute strength cannot yet match that of titanium alloys and high-strength steel. Improving the strength of aluminum-based materials to over 700 MPa to replace higher-density structural materials such as titanium and steel would be of great significance to the development of aerospace equipment. Summary of the Invention

[0003] The present invention aims to provide a method for preparing high-strength carbon nanotube reinforced aluminum matrix composite ring-shaped parts. The method uses a ring-shaped ingot of CNT-reinforced high-strength aluminum matrix alloy (one of the heat-treatable aluminum alloys such as Al-Cu, Al-Mg-Si, and Al-Zn-Mg-Cu) as raw material. By adjusting the ring rolling temperature to a moderate range (100 to 200°C below the solution temperature), the CNTs can be oriented along the ring rolling direction, promoting the full utilization of load transfer strengthening efficiency. At the same time, high-density dislocations are induced near the grain boundaries, providing nucleation sites for precipitates, reducing the content of precipitate-free bands after aging, thereby improving the strength level of the material.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A method for preparing a high-strength carbon nanotube reinforced aluminum matrix composite ring-shaped part, wherein the method uses a carbon nanotube (CNT) reinforced aluminum matrix composite ring billet as raw material and obtains a high-strength ring-shaped part (ring component) through a ring rolling process.

[0006] The method includes the following steps:

[0007] (1) Prepare carbon nanotube (CNT) reinforced aluminum matrix composite powder;

[0008] (2) The composite material powder from step (1) is loaded into a ring mold, and cold pressing and powder metallurgy sintering are performed in sequence to obtain a composite material ring billet.

[0009] (3) Perform multi-pass ring rolling on the billet obtained in step (2);

[0010] (4) The ring-rolled part obtained in step (3) is subjected to solution treatment and aging treatment in sequence to obtain the high-strength carbon nanotube reinforced aluminum matrix composite ring-shaped part.

[0011] In step (1) above, the preparation process of the carbon nanotube (CNT) reinforced aluminum matrix composite material is as follows: carbon nanotube (CNT) powder is blended with aluminum alloy powder (one of Al-Cu system, Al-Mg-Si system, Al-Zn-Mg-Cu system, etc. aluminum alloy powder), and CNT is uniformly dispersed in the aluminum alloy powder by high-energy ball milling to obtain CNT / Al composite powder, which is the carbon nanotube (CNT) reinforced aluminum matrix composite material.

[0012] The aluminum alloy powder has an average particle size of 0.1 μm to 200 μm, the CNT powder has an average radial dimension of 10 to 100 nm, the CNT powder accounts for 0.3-3 wt.% of the total powder (aluminum alloy powder + CNT powder), and the ball-to-material weight ratio of the high-energy ball mill is 10:1 to 30:1.

[0013] The aluminum alloy powder is one of the following: Al-Cu, Al-Mg-Si, and Al-Zn-Mg-Cu.

[0014] In step (2) above, the powder metallurgy sintering adopts vacuum hot pressing sintering, hot isostatic pressing or discharge ion beam sintering process under atmosphere or vacuum conditions, and the sintering temperature is 480-580℃.

[0015] In step (3) above, the ring rolling temperature is controlled between 100 and 200°C below the solution temperature of the aluminum-based composite material.

[0016] In step (4) above, the solution treatment temperature and aging temperature are selected according to the specific aluminum alloy grade.

[0017] In the annular irregular part prepared by the method of the present invention: CNTs are arranged along the circumferential direction in the annular component, and the content of grain boundary precipitates is extremely low. Under the combined effect of load transfer of the reinforcing phase (CNT) and dispersion strengthening of the precipitates, the strength level of the irregular ring part in the circumferential direction is extremely high.

[0018] The design mechanism of this invention is as follows:

[0019] Studies have shown that incorporating a certain proportion of carbon nanotubes (CNTs) into an aluminum matrix and ensuring their orderly orientation along the stress direction can fully leverage their load transfer capabilities, significantly improving the overall strength of the material. Furthermore, while high-strength aluminum alloy matrices are rich in high-density precipitates, large-sized non-precipitate bands inevitably appear near grain boundaries, hindering the material's high strength. Pre-deformation introduces dislocation defects into the matrix, providing nucleation sites for the precipitates near grain boundaries, thereby reducing the content of non-precipitate bands. The combined effect of CNT load transfer and reduced non-precipitate band content further enhances the strength of aluminum-based materials.

[0020] This invention uses a ring-shaped billet of CNT-reinforced high-strength aluminum alloy (one of the heat-treatable aluminum alloys such as Al-Cu, Al-Mg-Si, and Al-Zn-Mg-Cu) as raw material. By adjusting the ring rolling process, the CNTs can be oriented along the rolling direction, which promotes the full utilization of load transfer strengthening efficiency. At the same time, high-density dislocations are induced near the grain boundaries, providing nucleation sites for precipitates and reducing the content of precipitate-free bands after aging. This invention can prepare high-strength aluminum-based materials and provides a corresponding preparation method.

[0021] The advantages and beneficial effects of the high-strength aluminum-based composite ring-shaped part with CNT directional arrangement, extremely low content of grain boundary precipitates, and its preparation method are as follows:

[0022] 1. Compared with high-strength aluminum alloys, it has a higher strength level, such as a yield strength of over 600MPa and a tensile strength of over 700MPa.

[0023] 2. Compared with materials that have not undergone plastic deformation, the medium-temperature ring rolling process introduces high-density dislocations near the grain boundaries, which can induce the nucleation of precipitated phases and reduce the content of non-precipitated zones, thereby making the microstructure more uniform.

[0024] 3. The microstructure of composite materials can be controlled through plastic processing, with a high degree of controllability, and can be directly used for engineering mass production. Detailed Implementation

[0025] Example 1

[0026] 2009Al powder with an average particle size of 13 μm was mixed with 2 wt.% CNT powder with an average diameter of 15 nm using a high-energy ball mill at a ball-to-powder weight ratio of 15:1, a rotation speed of 350 rpm, and a maximum linear velocity of 4.4 m / s. The resulting mixture was vacuum sintered at 540℃ and 80 MPa for 2 hours. The sintered ingot was then ring rolled at 390℃ with a deformation ratio of 4:1. The annular shaped component was solution-treated at 500℃ for 2 hours, followed by artificial aging at 180℃ for 12 hours to obtain a high-performance component.

[0027] The CNT / 2009Al annular irregular part manufactured in this embodiment has a microstructure in which CNTs are oriented along the circumferential direction, a high-density Al2Cu phase is uniformly distributed in the matrix, no obvious precipitation bands are seen near the grain boundaries, and the circumferential tensile strength of the part reaches 730 MPa at room temperature.

[0028] Comparative Example 1

[0029] 2009Al powder with an average particle size of 13 μm was mixed with 2 wt.% CNT powder with an average diameter of 15 nm using a high-energy ball mill at a ball-to-powder ratio of 15:1, a rotation speed of 350 rpm, and a maximum linear velocity of 4.4 m / s. The mixed powder was then vacuum sintered at 540℃ and 80 MPa for 2 hours. The sintered ingot was then ring rolled at 450℃ with a deformation ratio of 4:1. The annular shaped component was solution-treated at 500℃ for 2 hours, followed by artificial aging at 180℃ for 12 hours to obtain the final component.

[0030] The CNT / 2009Al annular irregular part manufactured using this comparative example has a microstructure in which CNTs are oriented along the circumferential direction, and obvious non-precipitated bands are visible near the grain boundaries. The circumferential tensile strength of the part at room temperature reaches 680 MPa.

[0031] Example 2

[0032] 7055Al powder with an average particle size of 13 μm was mixed with CNT powder containing 1 wt.% and having an average diameter of 15 nm using a high-energy ball mill. The ball-to-powder weight ratio was 15:1, the milling speed was 350 rpm, and the maximum linear velocity was 4.4 m / s. The resulting mixture was vacuum sintered at 500℃ and 80 MPa for 2 hours. The sintered ingot was then ring rolled at 370℃ with a deformation ratio of 4:1. The annular shaped component was solution-treated at 480℃ for 1 hour, followed by artificial aging at 120℃ for 24 hours to obtain a high-performance component.

[0033] The CNT / 7055Al annular irregular part manufactured in this embodiment has a microstructure in which CNTs are oriented along the circumferential direction, a high-density MgZn2 phase is uniformly distributed in the matrix, no obvious precipitation bands are seen near the grain boundaries, and the circumferential tensile strength of the part reaches 820 MPa at room temperature.

[0034] Comparative Example 2

[0035] 7055Al powder with an average particle size of 13 μm was mixed with CNT powder containing 1 wt.% and having an average diameter of 15 nm using a high-energy ball mill at a ball-to-powder weight ratio of 15:1, a rotation speed of 350 rpm, and a maximum linear velocity of 4.4 m / s. The mixed powder was then vacuum sintered at 500℃ and 80 MPa for 2 hours. The sintered ingot was then ring rolled at 420℃ with a deformation ratio of 4:1. The annular shaped component was solution-treated at 480℃ for 1 hour, followed by artificial aging at 120℃ for 24 hours to obtain the final component.

[0036] Using this embodiment, CNT / 7055Al annular irregular parts can be manufactured. The microstructure shows that CNTs are oriented along the circumferential direction, and obvious non-precipitated bands can be seen near the grain boundaries. The circumferential tensile strength of the component at room temperature reaches 750 MPa.

[0037] Example 3

[0038] 6092Al powder with an average particle size of 13 μm was mixed with 2.5 wt.% CNT powder with an average diameter of 15 nm using a high-energy ball mill at a ball-to-powder weight ratio of 15:1, a rotation speed of 350 rpm, and a maximum linear velocity of 4.4 m / s. The resulting mixture was vacuum sintered at 580 °C and 80 MPa for 2 hours. The sintered ingot was then ring rolled at 420 °C with a deformation ratio of 4:1. The annular shaped component was solution-treated at 540 °C for 2 hours, followed by artificial aging at 170 °C for 6 hours to obtain a high-performance component.

[0039] The CNT / 6092Al annular irregular part manufactured in this embodiment has a microstructure in which CNTs are oriented along the circumferential direction, a high-density Mg2Si phase is uniformly distributed in the matrix, no obvious precipitation bands are seen near the grain boundaries, and the circumferential tensile strength of the part reaches 700MPa at room temperature.

[0040] Comparative Example 3

[0041] 6092Al powder with an average particle size of 13 μm was mixed with 2.5 wt.% CNT powder with an average diameter of 15 nm using a high-energy ball mill at a ball-to-powder weight ratio of 15:1, a rotation speed of 350 rpm, and a maximum linear velocity of 4.4 m / s. The mixed powder was then vacuum sintered at 580℃ and 80 MPa for 2 hours. The sintered ingot was then ring rolled at 300℃ with a deformation ratio of 4:1. Surface cracking occurred in the components during the fabrication process.

[0042] The above embodiments describe the present invention, but the embodiments are only for further elaboration on the features and advantages of the present invention, and are not intended to limit the scope of the claims of the present invention.

Claims

1. A method for preparing a high-strength carbon nanotube-reinforced aluminum matrix composite ring-shaped part, characterized in that: This method uses carbon nanotube (CNT) reinforced aluminum matrix composite ring billets as raw materials to obtain high-strength ring-shaped parts through ring rolling process; The method includes the following steps: (1) Prepare carbon nanotube (CNT) reinforced aluminum matrix composite powder, including aluminum alloy powder and CNT powder, wherein the proportion of CNT powder in the total powder is 0.3-3 wt.%; the preparation process of the carbon nanotube (CNT) reinforced aluminum matrix composite is as follows: carbon nanotube (CNT) powder and aluminum alloy powder are blended, and CNT is uniformly dispersed in aluminum alloy powder by high-energy ball milling to obtain CNT / Al composite powder, which is the carbon nanotube (CNT) reinforced aluminum matrix composite; the average particle size of the aluminum alloy powder is 0.1 μm to 200 μm, the average radial size of the CNT powder is 10 to 100 nm, and the ball-to-material weight ratio of the high-energy ball mill is 10:1 to 30:1; (2) The composite material powder from step (1) is loaded into a ring mold, and cold pressing and powder metallurgy sintering are performed in sequence to obtain a composite material ring billet. (3) Perform multiple ring rolling on the billet obtained in step (2); the ring rolling temperature is controlled between 100 and 200°C below the solution temperature of the aluminum-based composite material; (4) The ring-rolled part obtained in step (3) is subjected to solution treatment and aging treatment in sequence to obtain the high-strength carbon nanotube reinforced aluminum matrix composite ring-shaped part.

2. The method for preparing the high-strength carbon nanotube reinforced aluminum matrix composite ring-shaped part according to claim 1, characterized in that: The aluminum alloy powder is one of the following: Al-Cu, Al-Mg-Si, and Al-Zn-Mg-Cu aluminum alloy powders.

3. The method for preparing the high-strength carbon nanotube reinforced aluminum matrix composite ring-shaped part according to claim 1, characterized in that: In step (2), the powder metallurgy sintering adopts vacuum hot pressing sintering, hot isostatic pressing or discharge ion beam sintering process under atmosphere or vacuum conditions, and the sintering temperature is 480-580℃.

4. The method for preparing the high-strength carbon nanotube reinforced aluminum matrix composite ring-shaped part according to claim 1, characterized in that: In step (4), the solution treatment temperature and aging temperature are selected according to the aluminum alloy grade.