Multi-phase synergistically strengthened Al-Cu-Mg-Si-Re aluminum alloy and preparation method thereof

Abstract

The invention relates to the technical field of multiphase synergetic aluminum alloy materials, in particular to a multiphase synergetic reinforced Al-Cu-Mg-Si-Re aluminum alloy and a preparation method thereof, and the multiphase synergetic reinforced Al-Cu-Mg-Si-Re aluminum alloy comprises the following components in percentage by mass: 2.0 to 3.0 weight percent of Cu, 0.75 to 0.9 weight percent of Mg, 0.3 to 0.5 weight percent of Si, 0.1 to 0.2 weight percent of Mn, 0.1 to 0.2 weight percent of Fe, 0.05 to 0.15 weight percent of Re and the balance of A1 and inevitable impurities. The contradiction between the strength and the heat resistance of the 2-series aluminum alloy in a basic component system in actual occasion application is solved, and collaborative optimization to a certain degree is achieved through microstructure design (multiphase collaborative strengthening), heat-resistant element adding and an advanced preparation process.

Description

Technical Field

[0001] The present invention relates to the technical field of multiphase synergistic aluminum alloy materials, and in particular to a multiphase synergistically strengthened Al-Cu-Mg-Si-Re aluminum alloy and a preparation method thereof. Background Art

[0002] In recent years, aluminum alloys have been widely used as lightweight materials in the automotive industry, aerospace, marine and other equipment manufacturing fields. In the new energy vehicle sector, replacing steel with aluminum in engines has become a key trend in lightweighting. To meet the high-temperature service requirements of automotive engines operating in gas-fired environments, aluminum alloys capable of withstanding temperatures exceeding 200°C have become a hot research topic.

[0003] In traditional duralumin 2xxx aluminum alloys, Al2Cu and Al2CuMg are the two main strengthening phases. Al2Cu, which is coherent with the matrix, has good thermal stability and resistance to high-temperature coarsening, meeting the requirements of applications in high-temperature scenarios below 150°C. However, the improvement in room-temperature and high-temperature strength of aluminum alloys by a single Al2Cu phase is limited. Furthermore, further increasing the Cu content will reduce the alloy's plasticity.

[0004] In traditional 6xxx series aluminum alloys, cubic Mg2Si, which forms a semi-coherent lattice with the matrix, is the primary strengthening phase. Furthermore, the ceramic Mg2Si phase offers enhanced thermal stability, forming at approximately 450°C during equilibrium solidification, making it another ideal heat-resistant phase.

[0005] In Al-Cu-Mg-Si alloys, the formation of Mg2Si is affected by the Cu / Mg ratio. When the Cu / Mg ratio is greater than 4, Al2Cu and Al2CuMg are primarily formed, while when the Cu / Mg ratio is less than 4, Al2Cu and Mg2Si are primarily formed. Furthermore, the formation of Mg2Si is related to the Mg / Si ratio. When the Mg / Si ratio is close to 1.73, Mg2Si preferentially forms in the aluminum alloy matrix.

[0006] The single precipitation phase of the existing 2xxx aluminum alloy and 6xxx aluminum alloy has limited effect on improving the room temperature and high temperature strength of the aluminum alloy.

[0007] To fully utilize the properties of these two phases, this invention, through unique composition design, rolling forming, and heat treatment processes, has developed a novel aluminum alloy sheet with multiphase synergistic strengthening. This will provide a new direction for the research and development of heat-resistant aluminum alloys for new energy vehicle engine blocks. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a multiphase synergistically strengthened Al-Cu-Mg-Si-Re aluminum alloy and a preparation method thereof, which solves the contradiction between the strength and heat resistance of the 2 series aluminum alloys in the basic component system in actual applications. Through microstructure design (multiphase synergistic strengthening), addition of heat-resistant elements and advanced preparation technology, a certain degree of synergistic optimization is achieved.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0010] A multiphase synergistically strengthened Al-Cu-Mg-Si-Re aluminum alloy comprises the following components, calculated by mass percentage: 2.0-3.0 wt% of Cu, 0.75-0.9 wt% of Mg, 0.3-0.5 wt% of Si, 0.1-0.2 wt% of Mn, 0.1-0.2 wt% of Fe, 0.05-0.15 wt% of Re, and the balance being Al and unavoidable impurities.

[0011] By controlling the Cu / Mg ratio to less than 4, the main phases formed are Al2Cu and Mg2Si. In the alloy composition design, a Cu content of 2.0-3.0wt% is used, the Cu / Mg ratio is about 3, and considering the effect of Si on plasticity, the Si content is controlled at 0.3-0.5wt%.

[0012] Preferably, the mass percentage of a single impurity element is less than 0.2%, and the sum of the mass percentages of the impurity elements is less than 0.3%.

[0013] Preferably, Mg2Si is a precursor phase in the aluminum alloy, and Mg2Si and Al2Cu are multiphase synergistically strengthened, with a

[110] Mg2Si / /

[111] Al2Cu relationship existing between the two.

[0014] Among them, the morphology of the intragranular strengthening phase is mainly composed of small short rod-shaped Mg2Si as the precursor and the induced ellipsoidal Al2Cu phase. Mg2Si enhances the formation of Al2Cu by providing heterogeneous nucleation sites. Mg2Si and Al2Cu synergistically strengthen and enhance the high-temperature performance of aluminum alloys. Its high-temperature tensile strength at 250℃ reaches 250MPa, which has significant application value in the field of lightweighting. Among them,

[110] Mg2Si / /

[111] Al2Cu is a typical crystallographic orientation relationship. Its meaning and explanation are as follows: First, this is not a simple proportional relationship, but a parallel correspondence between specific crystal directions (crystallographic directions) in the two-phase lattice;

[110] Mg2Si represents the crystal direction index (Miller indices) of the close-packed or specific crystal direction in the Mg2Si phase;

[111] Al2Cu represents the corresponding crystal direction in the Al2Cu phase. The " / / " symbol indicates that the two crystal directions are parallel to each other in space.

[0015] Preferably, in the microstructure of the alloy, an Al6(FeMn, Re) grain boundary strengthening phase exists at the grain boundaries.

[0016] The method for preparing a multiphase synergistically strengthened Al-Cu-Mg-Si-Re aluminum alloy as described in any one of the above comprises the following steps:

[0017] S1, weighing the raw materials of each component according to the formula ratio;

[0018] S2, melting the raw materials in S1 into ingots through a metal mold under a gravity environment;

[0019] S3, subjecting the ingot obtained in step S1 to a two-stage homogenization treatment, the first stage: 320-380°C, holding temperature for 4-8 hours, the second stage: 460-520°C, holding temperature for 16-20 hours;

[0020] S4, the ingot homogenized in step S2 is kept at 460-520°C for 2 hours, then taken out for hot rolling, with a deformation of 90% and a final rolling thickness of 2 mm; then cold rolling is performed at room temperature with a deformation of 50%, and finally an aluminum alloy plate with a thickness of 1 mm is obtained.

[0021] The two-stage homogenization heat treatment provides the foundation for achieving a homogeneous material, preparing for subsequent rolling. Rolling (hot and cold rolling) improves the as-cast structure, modulates texture composition, and achieves work hardening. Solution heat treatment establishes a correlation between structural characteristics and performance.

[0022] Preferably, the raw materials in step S1 are: Si is an Al-20% Si master alloy, Cu is an Al-50% Cu master alloy, Mn is an Al-10% Mn master alloy, Re is a Re-35% Cu master alloy, and Mg is 99% pure Mg.

[0023] Preferably, the raw material ingot casting in step S2 specifically includes the following steps:

[0024] S21, first placing pure aluminum and a copper-rhenium master alloy in a crucible, heating and melting them in a resistance furnace, and then adding an aluminum-copper master alloy, an aluminum-silicon master alloy, an aluminum-manganese master alloy, and pure magnesium in order of their melting points. After each addition of the master alloy, sprinkle a prepared covering agent on the crucible to prevent oxidation.

[0025] S22, gently stir with a stirring rod to confirm that all the alloy is melted, use hexachloroethane to degas and remove impurities, let it stand for 10 minutes, and then skim off the slag;

[0026] S23, after cleaning the surface slag, wait until the temperature of the aluminum alloy melt reaches above 720℃ for pouring, take out the mold preheated in the 250℃ furnace, and inject the aluminum alloy melt into the mold.

[0027] Preferably, the heating and smelting temperature during the melting and casting in step S21 is 760-800°C.

[0028] Preferably, the pressing amount of hot rolling and cold rolling in step S3 is 0.5 mm, and the number of rolling passes is 5 times.

[0029] Beneficial effects of the present invention:

[0030] 1. This invention, for the first time, utilizes unique composition design, rolling forming, and heat treatment, as well as the unique low diffusion rate of trace Re (rhenium) and its ability to inhibit the diffusion of other components (inhibiting free silicon), to develop a new heat-resistant aluminum alloy with Mg2Si as a precursor phase and synergistic strengthening of Mg2Si and Al2Cu. The alloy exhibits a high-temperature mechanical tensile strength of greater than 200 MPa at 250°C and an elongation greater than 15%. Al6 (FeMn, Re) grain boundary strengthening phases exist at grain boundaries, and the intragranular strengthening phase morphology is primarily composed of small, short rod-shaped Mg2Si as a precursor, accompanied by an induced ellipsoidal Al2Cu phase. Mg2Si promotes the formation of Al2Cu by providing heterogeneous nucleation sites. This will provide a new direction for the research and development of heat-resistant aluminum alloys for new energy vehicle engine cylinders.

[0031] 2. The present invention controls the Cu / Mg ratio to be less than 4, mainly forming two phases, Al2Cu and Mg2Si. In the alloy composition design, a Cu content of 2.0 to 3.0 wt% is used, the Cu / Mg ratio is about 3, and considering the effect of Si on plasticity, the Si content is controlled at 0.3 to 0.5 wt%. In the initial cold-rolled plate, annealed microstructure and tensile fracture analysis, it was observed that the ellipsoidal Al2Cu phase is characterized by the presence of small short rod-shaped Mg2Si as a precursor. The essence of the synergistic effect of multiple phases is to achieve a denser distribution of nano-precipitated phases and complementary high-temperature performance through the interaction of multiple precipitated phases. This makes the multi-phase aluminum alloy containing Al2Cu and Mg2Si have better comprehensive mechanical properties than the single strengthening phase alloy. It solves the contradiction between the strength and heat resistance of the 2 series aluminum alloy in practical applications in the basic component system. Through microstructure design (multiphase synergistic strengthening), the addition of heat-resistant elements and advanced preparation technology, a certain degree of synergistic optimization is achieved.

[0032] 3. The present invention has experimentally demonstrated that the tensile strength of the Al-Cu-Mg-Si-Re aluminum alloy prepared by the present invention reaches more than 250 MPa at 250°C, while the comparative example (traditional aluminum alloy) is only 144 MPa. The strength is increased by 72.76%, which will provide a new direction for the research and development of heat-resistant aluminum alloys for new energy vehicle engine cylinders. The high-temperature performance demonstrated by the present invention can be applied to high-temperature (>200°C) scenarios with stringent requirements on lightweight and strength, and is especially irreplaceable in the aerospace field. With process improvements (such as nano-precipitation strengthening), its high-temperature performance boundaries are still expanding. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is an SEM / EDS analysis diagram of the aluminum alloy sample of Comparative Example 1 of the present invention;

[0034] Figure 2 This is an SEM / EDS analysis diagram of the aluminum alloy sample of Comparative Example 2 of the present invention;

[0035] Figure 3 This is a SEM / EDS analysis diagram of the aluminum alloy sample of Example 1 of the present invention;

[0036] Figure 4 TEM / EDS analysis diagram of the aluminum alloy sample of Example 2 of the present invention;

[0037] Figure 5 The hardness of the aluminum alloys of Comparative Example 1, Example 1 and Example 2 of the present invention after being exposed to heat at 280° C. for different times. DETAILED DESCRIPTION

[0038] In order to facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments and drawings. The contents mentioned in the embodiments are not intended to limit the present invention.

[0039] Example 1

[0040] S1, weigh the following raw materials according to the formula ratio: Cu 2.51wt%, Mg 0.885wt%, Si 0.35wt%, Mn 0.1wt%, Re 0.08wt%, and the balance Al and inevitable impurities; wherein Si is an Al-20% Si master alloy, Cu is an Al-50% Cu master alloy, Mn is an Al-10% Mn master alloy, Re is a Re-35% Cu master alloy, and Mg is 99% pure Mg.

[0041] S2, the raw materials in S1 are melted into ingots in a metal mold under a gravity environment: 1) pure aluminum (commercial pure aluminum containing 0.1-0.2 wt% Fe as an impurity) and a copper-rhenium master alloy are first placed in a crucible. After heating to 780°C in a resistance furnace and melting, aluminum-copper master alloy, aluminum-silicon master alloy, aluminum-manganese master alloy, and pure magnesium are added in order of the melting points of the elements. After each addition of the master alloy, a prepared covering agent is sprinkled on the ingot to prevent oxidation; 2) gently agitate with a stirring rod to confirm that all the alloys are melted, degas and remove impurities using hexachloroethane, and let it stand for 10 minutes before skimming; 3) after cleaning the surface scum, wait until the temperature of the aluminum alloy melt reaches above 720°C for pouring, remove the mold preheated in a 250°C boiling furnace, and inject the aluminum alloy melt into the mold.

[0042] S3, the ingot obtained in step S1 is subjected to a two-stage homogenization treatment, the first stage: 360°C, heat preservation for 6 hours, the second stage: 495°C, heat preservation for 18 hours.

[0043] S4, the ingot homogenized in step S2 is kept at 490°C for 2 hours, then taken out for hot rolling, with a deformation of 90% and a final rolling thickness of 2 mm; then cold rolling is performed at room temperature with a deformation of 50%, and finally an aluminum alloy plate with a thickness of 1 mm is obtained; wherein the downward pressure of hot rolling and cold rolling is 0.5 mm, and the number of rolling passes is 5.

[0044] Example 2

[0045] S1. Weigh the following raw materials according to the formula ratio: Cu 2.50%, Mg 0.80%, Si 0.35%, Mn 0.1%, Re 0.1%, and the balance Al and inevitable impurities; wherein Si is an Al-20% Si master alloy, Cu is an Al-50% Cu master alloy, Mn is an Al-10% Mn master alloy, Re is a Re-35% Cu master alloy, and Mg is 99% pure Mg.

[0046] S2, the raw materials in S1 are melted into ingots in a metal mold under a gravity environment: 1) pure aluminum (commercial pure aluminum containing 0.1-0.2 wt% Fe as an impurity) and a copper-rhenium master alloy are first placed in a crucible. After heating to 780°C in a resistance furnace and melting, aluminum-copper master alloy, aluminum-silicon master alloy, aluminum-manganese master alloy, and pure magnesium are added in order of the melting points of the elements. After each addition of the master alloy, a prepared covering agent is sprinkled on the ingot to prevent oxidation; 2) gently agitate with a stirring rod to confirm that all the alloys are melted, degas and remove impurities using hexachloroethane, and let it stand for 10 minutes before skimming; 3) after cleaning the surface scum, wait until the temperature of the aluminum alloy melt reaches above 720°C for pouring, remove the mold preheated in a 250°C boiling furnace, and inject the aluminum alloy melt into the mold.

[0047] S3, the ingot obtained in step S1 is subjected to a two-stage homogenization treatment, the first stage: 345°C, heat preservation for 6 hours, the second stage: 495°C, heat preservation for 18 hours.

[0048] S4, the ingot homogenized in step S2 is kept at 460-520°C for 2 hours, then taken out for hot rolling, with a deformation of 90% and a final rolling thickness of 2 mm; then cold rolling is performed at room temperature with a deformation of 50%, and finally an aluminum alloy plate with a thickness of 1 mm is obtained; wherein the downward pressure of hot rolling and cold rolling is 0.5 mm, and the number of rolling passes is 5.

[0049] Comparative Example 1

[0050] The same as Example 1, except that Re is not added:

[0051] S1. Weigh the following raw materials according to the formula ratio: Cu 2.51wt%, Mg 0.885wt%, Si 0.35wt%, Mn 0.1wt%, and the balance Al and inevitable impurities; wherein Si is an Al-20% Si master alloy, Cu is an Al-50% Cu master alloy, Mn is an Al-10% Mn master alloy, Re is a Re-35% Cu master alloy, and Mg is 99% pure Mg.

[0052] S2, the raw materials in S1 are melted into ingots in a metal mold under a gravity environment: 1) pure aluminum (commercial pure aluminum containing 0.1-0.2 wt% Fe as an impurity) and a copper-rhenium master alloy are first placed in a crucible. After heating to 780°C in a resistance furnace and melting, aluminum-copper master alloy, aluminum-silicon master alloy, aluminum-manganese master alloy, and pure magnesium are added in order of the melting points of the elements. After each addition of the master alloy, a prepared covering agent is sprinkled on the ingot to prevent oxidation; 2) gently agitate with a stirring rod to confirm that all the alloys are melted, degas and remove impurities using hexachloroethane, and let it stand for 10 minutes before skimming; 3) after cleaning the surface scum, wait until the temperature of the aluminum alloy melt reaches above 720°C for pouring, remove the mold preheated in a 250°C boiling furnace, and inject the aluminum alloy melt into the mold.

[0053] S3, the ingot obtained in step S1 is subjected to a two-stage homogenization treatment, the first stage: 360°C, heat preservation for 6 hours, the second stage: 495°C, heat preservation for 18 hours.

[0054] S4, the ingot homogenized in step S2 is kept at 490°C for 2 hours, then taken out for hot rolling, with a deformation of 90% and a final rolling thickness of 2 mm; then cold rolling is performed at room temperature with a deformation of 50%, and finally an aluminum alloy plate with a thickness of 1 mm is obtained; wherein the downward pressure of hot rolling and cold rolling is 0.5 mm, and the number of rolling passes is 5.

[0055] Comparative Example 2

[0056] The method is basically the same as Example 1, except that the content of Cu is greater than 3.0 wt%.

[0057] S1, weigh the raw materials of each component according to the formula ratio: Cu4.5wt% , Mg 0.885wt%, Si 0.35wt%, Mn 0.1wt%, Re 0.08wt%, the balance being Al and inevitable impurities; wherein, Si is an Al-20% Si master alloy, Cu is an Al-50% Cu master alloy, Mn is an Al-10% Mn master alloy, Re is a Re-35% Cu master alloy, and Mg is pure Mg with a content of 99%.

[0058] S2, the raw materials in S1 are melted into ingots in a metal mold under a gravity environment: 1) pure aluminum (commercial pure aluminum containing 0.1-0.2 wt% Fe as an impurity) and a copper-rhenium master alloy are first placed in a crucible. After heating to 780°C in a resistance furnace and melting, aluminum-copper master alloy, aluminum-silicon master alloy, aluminum-manganese master alloy, and pure magnesium are added in order of the melting points of the elements. After each addition of the master alloy, a prepared covering agent is sprinkled on the ingot to prevent oxidation; 2) gently agitate with a stirring rod to confirm that all the alloys are melted, degas and remove impurities using hexachloroethane, and let it stand for 10 minutes before skimming; 3) after cleaning the surface scum, wait until the temperature of the aluminum alloy melt reaches above 720°C for pouring, remove the mold preheated in a 250°C boiling furnace, and inject the aluminum alloy melt into the mold.

[0059] S3, the ingot obtained in step S1 is subjected to a two-stage homogenization treatment, the first stage: 360°C, heat preservation for 6 hours, the second stage: 495°C, heat preservation for 18 hours.

[0060] S4, the ingot homogenized in step S2 is kept at 490°C for 2 hours, then taken out for hot rolling, with a deformation of 90% and a final rolling thickness of 2 mm; then cold rolling is performed at room temperature with a deformation of 50%, and finally an aluminum alloy plate with a thickness of 1 mm is obtained; wherein the downward pressure of hot rolling and cold rolling is 0.5 mm, and the number of rolling passes is 5.

[0061] Test Example 1

[0062] Performance tests were conducted on the aluminum alloy plates of Example 1, Example 2, Comparative Example 1, and Comparative Example 2. The test results are shown in Tables 1 and 2 below.

[0063] Table 1 250℃ high temperature tensile properties of aluminum alloy plates

[0064]

[0065] Table 2 Hardness and conductivity test results of aluminum alloy plates

[0066]

[0067] refer to Figures 1 to 4 SEM / EDS analysis diagram and Figure 5 It can be seen that:

[0068] Among them, Figure 4 It can be clearly seen that Mg2Si and Al2Cu agglomerate very obviously, and under the action of Re element, the aluminum alloy forms a multiphase synergistic strengthening of the aluminum alloy with Mg2Si as the precursor phase and Mg2Si and Al2Cu.

[0069] Example 3

[0070] S1. Weigh the following raw materials according to the formula ratio: Cu 2.01wt%, Mg 0.75wt%, Si 0.5wt%, Mn 0.1wt%, Re 0.05wt%, with the balance being Al and unavoidable impurities. Among them, Si is an Al-20% Si master alloy, Cu is an Al-50% Cu master alloy, Mn is an Al-10% Mn master alloy, Re is a Re-35% Cu master alloy, and Mg is 99% pure Mg.

[0071] S2, the raw materials in S1 are melted into ingots in a metal mold under a gravity environment: 1) pure aluminum (commercial pure aluminum containing 0.1-0.2 wt% Fe as an impurity) and a copper-rhenium master alloy are first placed in a crucible. After heating to 760°C in a resistance furnace and melting, aluminum-copper master alloy, aluminum-silicon master alloy, aluminum-manganese master alloy, and pure magnesium are added in order of the melting points of the elements. After each addition of the master alloy, a prepared covering agent is sprinkled on the ingots to prevent oxidation; 2) gently agitate with a stirring rod to confirm that all the alloys are melted, degas and remove impurities using hexachloroethane, and let it stand for 10 minutes before skimming; 3) after cleaning the surface scum, wait until the temperature of the aluminum alloy melt reaches above 720°C for pouring, remove the mold preheated in a 250°C boiling furnace, and inject the aluminum alloy melt into the mold.

[0072] S3, the ingot obtained in step S1 is subjected to a two-stage homogenization treatment, the first stage: 370°C, heat preservation for 8 hours, the second stage: 510°C, heat preservation for 16 hours.

[0073] S4, the ingot homogenized in step S2 is kept at 500°C for 2 hours, then taken out for hot rolling, with a deformation of 90% and a final rolling thickness of 2 mm; then cold rolling is performed at room temperature with a deformation of 50%, and finally an aluminum alloy plate with a thickness of 1 mm is obtained; wherein the downward pressure of hot rolling and cold rolling is 0.5 mm, and the number of rolling passes is 5.

[0074] Example 4

[0075] S1. Weigh the following raw materials according to the formula ratio: Cu 3.01wt%, Mg 0.995wt%, Si 0.305wt%, Mn 0.2wt%, Re 0.15wt%, with the balance being Al and unavoidable impurities. Si is an Al-20% Si master alloy, Cu is an Al-50% Cu master alloy, Mn is an Al-10% Mn master alloy, Re is a Re-35% Cu master alloy, and Mg is 99% pure Mg.

[0076] S2, the raw materials in S1 are melted into ingots in a metal mold under a gravity environment: 1) pure aluminum (commercial pure aluminum containing 0.1-0.2 wt% Fe as an impurity) and a copper-rhenium master alloy are first placed in a crucible. After heating to 780°C in a resistance furnace and melting, aluminum-copper master alloy, aluminum-silicon master alloy, aluminum-manganese master alloy, and pure magnesium are added in order of the melting points of the elements. After each addition of the master alloy, a prepared covering agent is sprinkled on the ingot to prevent oxidation; 2) gently agitate with a stirring rod to confirm that all the alloys are melted, degas and remove impurities using hexachloroethane, and let it stand for 10 minutes before skimming; 3) after cleaning the surface scum, wait until the temperature of the aluminum alloy melt reaches above 720°C for pouring, remove the mold preheated in a 250°C boiling furnace, and inject the aluminum alloy melt into the mold.

[0077] S3, the ingot obtained in step S1 is subjected to a two-stage homogenization treatment, the first stage: 325°C, heat preservation for 8 hours, the second stage: 465°C, heat preservation for 20 hours.

[0078] S4, the ingot homogenized in step S2 is kept at 460°C for 2 hours, then taken out for hot rolling, with a deformation of 90% and a final rolling thickness of 2 mm; then cold rolling is performed at room temperature with a deformation of 50%, and finally an aluminum alloy plate with a thickness of 1 mm is obtained; wherein the downward pressure of hot rolling and cold rolling is 0.5 mm, and the number of rolling passes is 5.

[0079] Test Example 2

[0080] Performance tests were conducted on the aluminum alloy plates of Example 3 and Example 4, and the test results are shown in Tables 1 and 2 below.

[0081] Table 1 250℃ high temperature tensile properties of aluminum alloy plates

[0082]

[0083] Table 2 Hardness and conductivity test results of aluminum alloy plates

[0084]

[0085] All technical features in this embodiment can be modified in appearance according to actual needs.

[0086] The above embodiments are preferred implementation schemes of the present invention. In addition, the present invention can also be implemented in other ways. Any obvious replacement without departing from the concept of the present technical solution is within the scope of protection of the present invention.

Claims

1. A multiphase synergistically strengthened Al-Cu-Mg-Si-Re aluminum alloy, characterized by: Calculated by mass percentage, it contains the following components: 2.0-3.0wt% Cu, 0.75-0.9wt% Mg, 0.3-0.5wt% Si, 0.1-0.2wt% Mn, 0.1-0.2wt% Fe, 0.05-0.15wt% Re, and the balance is Al and unavoidable impurities.

2. The multiphase synergistically strengthened Al-Cu-Mg-Si-Re aluminum alloy according to claim 1, characterized in that: The mass percentage of a single impurity element is less than 0.2%, and the sum of the mass percentages of impurity elements is less than 0.3%.

3. The multiphase synergistically strengthened Al-Cu-Mg-Si-Re aluminum alloy according to claim 1, characterized in that: In this aluminum alloy, Mg2Si is a precursor phase, and Mg2Si and Al2Cu multiphases are synergistically strengthened, and there is a [110]Mg2Si / / [111]Al2Cu relationship between the two.

4. The multiphase synergistically strengthened Al-Cu-Mg-Si-Re aluminum alloy according to claim 1, characterized in that: In the microstructure of the alloy, Al6(FeMn, Re) grain boundary strengthening phase exists at the grain boundaries.

5. The method for preparing a multiphase synergistically strengthened Al-Cu-Mg-Si-Re aluminum alloy according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, weighing the raw materials of each component according to the formula ratio; S2, melting the raw materials in S1 into ingots through a metal mold under a gravity environment; S3, subjecting the ingot obtained in step S1 to a two-stage homogenization treatment, the first stage: 320-380°C, holding temperature for 4-8 hours, the second stage: 460-520°C, holding temperature for 16-20 hours; S4, the ingot homogenized in step S2 is kept at 460-520°C for 2 hours and then hot rolled to a deformation amount of 90% and a final rolling thickness of 2 mm; Then, the sheet is cold rolled at room temperature with a deformation of 50%, and finally an aluminum alloy sheet with a thickness of 1 mm is obtained.

6. The method for preparing a multiphase synergistically strengthened Al-Cu-Mg-Si-Re aluminum alloy according to claim 5, characterized in that: The raw materials in step S1 are specifically: Si is an Al-20% Si master alloy, Cu is an Al-50% Cu master alloy, Mn is an Al-10% Mn master alloy, Re is a Re-35% Cu master alloy, and Mg is 99% pure Mg.

7. The multiphase synergistically strengthened Al-Cu-Mg-Si-Re aluminum alloy and the preparation method thereof according to claim 6, characterized in that: The raw material ingot casting in step S2 specifically includes the following steps: S21, first placing pure aluminum and a copper-rhenium master alloy in a crucible, heating and melting them in a resistance furnace, and then adding an aluminum-copper master alloy, an aluminum-silicon master alloy, an aluminum-manganese master alloy, and pure magnesium in order of their melting points. After each addition of the master alloy, sprinkle a prepared covering agent on the crucible to prevent oxidation. S22, gently stir with a stirring rod to confirm that all the alloy is melted, use hexachloroethane to degas and remove impurities, let it stand for 10 minutes, and then skim off the slag; S23, after cleaning the surface slag, wait until the temperature of the aluminum alloy melt reaches above 720℃ for pouring, take out the mold preheated in the 250℃ furnace, and inject the aluminum alloy melt into the mold.

8. The multiphase synergistically strengthened Al-Cu-Mg-Si-Re aluminum alloy and the preparation method thereof according to claim 7, characterized in that: The heating and smelting temperature during the melting and casting in step S21 is 760-800°C.

9. The multiphase synergistically strengthened Al-Cu-Mg-Si-Re aluminum alloy and the preparation method thereof according to claim 5, characterized in that: In step S3, the pressing amount of hot rolling and cold rolling is 0.5 mm, and the number of rolling passes is 5 times.

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