High-strength high-thermal-stability aluminum alloy, preparation method and application thereof

Abstract

The application discloses a high-strength and high-thermal-stability aluminum alloy as well as a preparation method and application thereof, and belongs to the technical field of aluminum alloy materials. The alloy contains QP-II phases, QP-II / GPB composite phases and beta'' phases; the cross-sectional size of the QP-II phases is 2-10 nm, the cross-sectional size of the beta'' phases is 2-20 nm, and the QP-II / GPB composite phases are composed of GPB zones that are segregated on QP-II interfaces; the QP-II / GPB composite phases account for 70-90% of the total precipitated phase quantity in the alloy, and the QP-II phases account for 10-20% of the total precipitated phase quantity in the alloy. The heat-resistant and reinforced 6000 series aluminum alloy developed by the application can increase the upper limit of the service temperature from the existing 120 DEG C to above 200 DEG C, and can keep stable mechanical properties in the 200 DEG C interval.

Description

Technical Field

[0001] This invention relates to a high-strength, high-thermal-stability aluminum alloy, its preparation method, and its applications. More particularly, it relates to a novel high-strength, high-thermal-stability aluminum alloy based on a QP-II / GPB core-shell structure composite phase as the main strengthening phase, its preparation method, and its applications. Specifically, it relates to the composition design and preparation process of a novel 6000 series aluminum alloy. This invention belongs to the field of aluminum alloy materials technology. Background Technology

[0002] 6000 series aluminum alloys (Al-Mg-Si series), with their excellent formability, weldability, and moderate strength, have become core structural materials in the automotive, rail transportation, and electronic equipment industries, and are widely used in vehicle body frames, engine peripheral components, and rail vehicle connectors. However, with the increasing demands of modern industry for lightweight equipment and high-temperature service stability, the heat resistance limitations of 6000 series aluminum alloys are becoming increasingly apparent, severely restricting their application in higher-temperature conditions. Currently used high-temperature service materials in industry, such as heat-resistant steel and titanium alloys, while meeting temperature requirements, have high densities and cannot meet the demands of lightweight development. Existing heat resistance improvement methods for 6000 series aluminum alloys are mostly focused on single-element doping or heat treatment process optimization. The currently developed heat-resistant reinforced 6000 series aluminum alloys have an upper service temperature limit of 120℃, and have problems such as limited strengthening effect and complex process. They are difficult to simultaneously take into account high-temperature stability and original forming and processing performance, and cannot meet the comprehensive requirements of materials for high-temperature conditions such as automotive engine compartments and rail transit braking systems. Developing 6000 series aluminum alloys that combine lightweight and excellent heat resistance has become an urgent need in the industry. Summary of the Invention

[0003] The technical problem to be solved by this invention is to provide a high-strength, high-thermal-stability aluminum alloy.

[0004] Meanwhile, this invention provides a method for preparing a high-strength, high-thermal-stability aluminum alloy.

[0005] Meanwhile, this invention provides an application of high-strength, high-thermal-stability aluminum alloy in high-temperature working conditions such as automotive engine compartments and rail transit braking systems.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: This invention is achieved by synergistically controlling the Mg / Si ratio and Cu content to achieve a QP-II / GPB core-shell composite precipitate content of 70-90% in the alloy, with the QP-II phase accounting for less than 10%. Compared to the QP-II phase alone, the GPB region forms a stepped nucleation at the QP-II phase interface, inhibiting Cu diffusion into the precipitate and preventing nucleation at the QP-II phase interface. This QP-II / GPB composite precipitate exhibits extremely high stability during long-term overaging, endowing the alloy with excellent thermal stability. These findings provide new insights for designing next-generation heat-resistant aluminum alloys.

[0007] In addition, regarding the heat treatment process, the homogenization heat treatment involves heating at 30-100℃ / h to 550-570℃, holding at that temperature for 4-10 hours, and then air-cooling to room temperature; the alloy deformation temperature is 350℃~500℃, and the deformation rate is 0.001~10 s. −1 This ensures that no defects are generated in the alloy during deformation, while maintaining a high-density subgrain structure, further improving the alloy's strengthening ability. In the solution aging process, to ensure that the ratio of thermally exposed QP-II / GPB phase reaches more than 90% after artificial aging, a three-stage aging process is adopted. The first stage of artificial aging is at 170-180℃ for 1-20 hours, the second stage is at 180-220℃ for 3-10 hours, and the third stage is at 150-170℃ for 1-5 hours.

[0008] A high-strength, high-thermal-stability aluminum alloy, wherein the aluminum alloy is an Al-Mg-Si based aluminum alloy, and its microstructure has the following characteristics: the alloy contains a QP-II phase, a QP-II / GPB composite phase, and a β" phase. The QP-II phase is a lamellar precipitate containing Al, Si, Mg, and Cu elements, with a cross-sectional size of 2-10 nm. The β" phase is a needle-like precipitate containing Si and Mg elements, with a cross-sectional size of 2-20 nm. The QP-II / GPB composite phase is composed of GPB regions segregated at the QP-II interface. The QP-II / GPB composite phase accounts for 70-90% of the total number of precipitates in the alloy, and the QP-II phase accounts for 10-20% of the total number of precipitates in the alloy.

[0009] In the Al-Mg-Si aluminum alloy, Mg accounts for 1-4 wt.%, Si accounts for 0.43-1.4 wt.%, Cu accounts for 0.5-2.0 wt.%, Mn accounts for 0.09-0.5 wt.%, and Cr accounts for 0.03-0.17 wt.

[0010] In the Al-Mg-Si aluminum alloy, the Mg / Si ratio is 2.3~3.2, the Mg / Cu ratio is 2~3, and the Mn / Cr ratio is 3.

[0011] Preferably, in the Al-Mg-Si aluminum alloy, the Mg / Si ratio is 2.3~2.8, the Mg / Cu ratio is 2~2.4, and the Mn / Cr ratio is 3.

[0012] The QP-II phase is lath-shaped with a cross-sectional size of 2-10 nm. The GPB region is a precursor phase of the S(Al2CuMg) phase in the Al-Cu-Mg alloy, and its composition is Mg. (2x+2) Cu (2x+2) Al (3x-1) x ranges from 0 to 0.3.

[0013] A method for preparing a high-strength, high-thermal-stability aluminum alloy involves solidifying a designed alloy composition to obtain an aluminum alloy billet, then homogenizing the billet to obtain a homogenized aluminum alloy billet, followed by cold rolling and hot rolling to obtain a rolled aluminum alloy product, then aging the rolled aluminum alloy product to obtain an aged aluminum alloy product, and finally, hot-exposed treatment of the peak-aged aluminum alloy to obtain a hot-exposed aluminum alloy product.

[0014] Preferably, the solidification forming method is not limited to aluminum alloy casting technology, 3D printing technology, and spray forming technology, and the obtained aluminum alloy billet is not limited to round cast rods, square rods, hollow cast rods, flat ingots, and irregularly shaped ingots.

[0015] Preferably, the pressure processing deformation process is not limited to one or more combinations of rolling, extrusion, and forging, wherein the deformation temperature is 350℃~500℃ and the deformation rate is 0.001~10 s. -1 .

[0016] Preferably, the homogenization heat treatment process involves heating the temperature at 30℃ / h~100℃ / h to 550℃~570℃, holding it at that temperature for 4~10 hours, and then air-cooling it to room temperature.

[0017] Preferably, the pressure deformation process is not limited to deformation methods such as rolling, extrusion, and forging, wherein the deformation temperature is 350 ≤ T3 ≤ 500 °C, and the deformation rate is 0.001~10 s. -1 .

[0018] Preferably, the offline solution treatment temperature is 520℃~580℃, the holding time is 10min~6h, the quenching water temperature is 10℃~70℃, and the quenching transfer time interval is less than 30s.

[0019] Preferably, online quenching is not limited to one or more of air cooling, water cooling, water mist cooling, and water curtain cooling.

[0020] Preferably, in order to achieve a QP-II / GPB composite phase ratio of over 90% after artificial aging, a three-stage aging process is adopted. The first stage of artificial aging is performed at a temperature of 170–180℃ for 1–20 hours, the second stage at a temperature of 180–220℃ for 3–10 hours, and the third stage at a temperature of 150–170℃ for 1–5 hours.

[0021] Preferably, cold working can be performed after rolling, with a cold working deformation rate of 1-3%.

[0022] Specifically, a method for preparing a high-strength, high-thermal-stability aluminum alloy includes the following steps: Step one: In the alloy composition design, the alloy composition is controlled at Mg / Si = 2.3~3.2, Mg / Cu = 2~3, and Mn / Cr = 3. The alloy is prepared using 99.98% industrial pure aluminum, pure Mg, Al-Si master alloy, Al-Cu master alloy, Al-Mn master alloy, and Al-Cr master alloy as raw materials. The alloy is produced by semi-continuous casting at a casting temperature of 690℃~750℃ and a cooling rate of 50~90mm / min. The cast rod has a diameter of 178mm and a length of 2 meters. A small piece is cut along the casting direction, with dimensions of 70×35×20mm (length×width×height), and then subjected to homogenization heat treatment. The temperature is increased to 550-570℃ at a rate of 30-100℃ / h, held for 4-10h, and then air-cooled to room temperature.

[0023] After homogenization, the material is milled and then hot rolled in six passes at 480℃~520℃ (7mm each time), reducing the thickness from 48mm to 6mm. The hot rolling exit temperature is 350-400℃. Then, it is cold rolled from 6mm to 4mm, followed by intermediate annealing at 350℃~430℃ for 1-5 hours, and then cold rolled in two more passes to the final thickness of 1mm, with each pass removing two 2mm sections. The rolled profiles were first solution-treated (520℃~580℃, holding time 10min~6h), then water-quenched (quenching water temperature 10℃~70℃, quenching transfer time less than 30s) to room temperature, and immediately subjected to three-stage artificial aging treatment: the first stage artificial aging temperature was 170~180℃, time was 1h~20h; the second stage artificial aging temperature was 180~220℃, time was 3~10h; and the third stage artificial aging temperature was 150~170℃, time was 1~5h. Finally, a heat exposure test was conducted at 200℃.

[0024] A high-strength, high-thermal-stability aluminum alloy is prepared by a method for preparing a high-strength, high-thermal-stability aluminum alloy according to the present invention.

[0025] A high-strength, high-thermal-stability aluminum alloy exhibits the following properties: at room temperature, the alloy has a tensile strength exceeding 470 MPa, a yield strength exceeding 429 MPa, and an elongation exceeding 9%. At 200°C, the alloy's tensile strength exceeds 360 MPa, its yield strength exceeds 290 MPa, and its elongation exceeds 8%.

[0026] Application of a high-strength, high-thermal-stability aluminum alloy in the manufacture of profiles, plates, and forgings used in aerospace, defense, high-speed rail, automobiles, bicycles, pressure vessels, construction, power, and photovoltaic fields.

[0027] Application of a high-strength, high-thermal-stability aluminum alloy in high-temperature applications such as automotive engine compartments, rail transit braking systems, and wire materials for new energy vehicles.

[0028] A heat-resistant aluminum alloy component is prepared from a high-strength, high-thermal-stability aluminum alloy according to the present invention.

[0029] The heat-resistant reinforced 6000 series aluminum alloy developed in this invention can raise the upper limit of service temperature from the current 120℃ to over 200℃, maintaining stable mechanical properties within the 200℃ range. It can directly replace some heat-resistant steels and titanium alloys in high-temperature components, significantly reducing the overall weight of equipment and contributing to the achievement of lightweighting goals in the industrial sector. It has significant application potential in the manufacture of profiles, plates, and forgings used in aerospace, defense, high-speed rail, automotive, bicycle, pressure vessels, construction, and photovoltaic fields.

[0030] The present invention has the following beneficial effects: Traditional 6000 series aluminum alloys primarily utilize the β-phase as the main strengthening phase, but suffer from problems such as slow precipitation rate, low strengthening capacity, and insufficient thermal stability. This invention, combining the compositional characteristics of 6000 and 5000 series aluminum alloys, develops a novel 6000 series aluminum alloy with a QP-II / GPB core-shell structure composite phase as the main strengthening phase. By controlling the Mg / Si ratio and Cu content within a certain range, a special core-shell structure composite phase is formed in the alloy. Notably, this composite phase is derived from the GPB region (Mg...) of the S-phase precursor phase in the Al-Cu-Mg alloy system. (2x+2) Cu (2x+2) Al (3x-1)The composite precipitate is composed of the QP-II phase in Al-Mg-Si-Cu alloys, and the β″ phase, the main strengthening phase in traditional 6xxx series alloys, is significantly reduced. This composite precipitate structure can effectively suppress the coarsening of alloy precipitates, greatly improve the precipitation strengthening ability of the alloy, and exhibit extremely high stability during long-term overaging, giving the alloy excellent thermal stability and significantly improving the strength and heat resistance of the alloy. These findings provide new ideas for the design and development of next-generation heat-resistant aluminum alloys; and ultimately, a heat-resistant aluminum alloy with higher strength than traditional 6000 series aluminum alloys was developed.

[0031] The alloy is characterized in that the proportion of the QP-II / GPB composite phase in the alloy reaches 70-90% of all nano-precipitated phases, and the cross-sectional size of the QP-II phase reaches 2-10 nm, while the proportion of the QP-II phase in the alloy is less than 10%. Attached Figure Description

[0032] Figure 1 The image shows a HAADF-STEM image of the QP-II / GPB phase after peak aging and 200°C heat exposure of the alloy of the present invention. Figure 2 This is a bright-field TEM image of the nano-precipitates exposed by heat after peak aging of the alloy in Example 1 of this invention; Figure 3 The image is a bright-field TEM image of the nano-precipitates exposed by heat after peak aging of alloy 1 in Comparative Example 1. Figure 4 The image is a bright-field TEM image of the nano-precipitates exposed by heat after peak aging of alloy 2 in Comparative Example 2. Figure 5 This is a bright-field TEM image of the nano-precipitates exposed by heat after peak aging of alloy 3 (Comparative Example 3). Detailed Implementation

[0033] The present invention will be further described in detail below with reference to specific embodiments. The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Example 1

[0034] In terms of alloy composition design, the alloy composition is controlled at Mg / Si = 2.3, Mg / Cu = 2, and Mn / Cr = 3. Specifically, the alloy composition is: Mg 2.3 wt.%, Si 1.0 wt.%, Cu 1.15 wt.%, Mn 0.3 wt.%, and Cr 0.1 wt.%. The alloy is prepared using 99.98% industrial pure aluminum, pure Mg, Al-Si master alloy, Al-Cu master alloy, Al-Mn master alloy, and Al-Cr master alloy as raw materials. The alloy is produced using semi-continuous casting. A 20 mm thick cuboid is cut along the casting direction. A small piece measuring 70 × 35 × 20 mm (length × width × height) is taken from the cuboid and then subjected to homogenization heat treatment, heated to 560 °C at a rate of 50 °C / h, held for 6 h, and then air-cooled to room temperature.

[0035] The homogenized material was hot-rolled six times at 510℃ (7mm per pass), reducing the thickness from 48mm to 6mm. The hot-rolling exit temperature was 380℃. It was then cold-rolled from 6mm to 4mm, followed by intermediate annealing at 400℃ for 2 hours, and then cold-rolled twice to a final thickness of 1mm, with two 2mm passes each time. The rolled profile was first solution-treated, then water-quenched to room temperature, and immediately subjected to a three-stage artificial aging treatment: the first stage was at 180℃ for 6 hours, the second stage at 200℃ for 5 hours, and the third stage at 150℃ for 3 hours. Finally, a heat exposure test was conducted at 200℃.

[0036] Hardness testing was performed with a load of 500g and a holding time of 10s. At least 10 points were taken from the entire surface of each sample to ensure data accuracy, with an error not exceeding ±3%. Tensile properties at room temperature were tested on a computer-controlled extensometer at a tensile rate of 1.5mm / min. Three parallel specimens were used for each sample. After fracture, the yield strength σ was calculated according to the national standard GB / T228-2002. s Tensile strength σ b The elongation δ was also measured. The microstructure of the alloy was observed using transmission electron microscopy, while atomic resolution HAADF-STEM was performed using an aberration-corrected electron microscope with an accelerating voltage of 300 kV. The QP-II / GPB composite phase was identified by determining whether a GPB substructure was formed at the interface between the coherent and semi-lattice phases of QP-II. The transmission sample was prepared using an electrolytic double-jet system. The double-jet solution was 70% methanol + 30% nitric acid, the temperature was -25℃ to -30℃, the voltage was 15 to 20 V, and the current was 50 to 70 mA.

[0037] Examples 2 to 3, and Comparative Examples 1 to 2 are basically the same as Example 1, except that the alloy composition design is different, while the subsequent deformation, processing and heat treatment processes are basically the same.

[0038] In Example 2, Mg / Si = 2.8, Mg / Cu = 2.4, and Mn / Cr = 3; Specifically, the alloy composition is as follows: Mg 2.8 wt.%, Si 1.0 wt.%, Cu 1.15 wt.%, Mn 0.5 wt.%, and Cr 0.17 wt.%.

[0039] In Example 3, Mg / Si = 3.2, Mg / Cu = 3, and Mn / Cr = 3; Specifically, the alloy composition is as follows: Mg 3.2 wt.%, Si 1.0 wt.%, Cu 1.07 wt.%, Mn 0.36 wt.%, and Cr 0.12 wt.%.

[0040] In Comparative Example 1, Mg / Si = 4.5, Mg / Cu = 1.6, and Mn / Cr = 3; Specifically, the alloy composition is as follows: Mg 4.5 wt.%, Si 1.0 wt.%, Cu 2.8 wt.%, Mn 0.36 wt.%, and Cr 0.12 wt.%.

[0041] In Comparative Example 2, Mg / Si = 5.4, Mg / Cu = 1.8, and Mn / Cr = 3.

[0042] Specifically, the alloy composition is as follows: Mg 5.4 wt.%, Si 1.0 wt.%, Cu 3.0 wt.%, Mn 0.36 wt.%, and Cr 0.12 wt.%.

[0043] Comparative Example 3: The only difference between this comparative example and Example 1 is that it adopts a first-level artificial aging treatment: the artificial aging process is 180℃-6h.

[0044] Experimental results (1) Tensile properties Table 1 compares the tensile strength, yield strength, and elongation of the alloys in Examples 1 to 3 and Comparative Examples 1 to 2 after reaching peak aging. It can be seen that in Example 1, when Mg / Si = 2.3, Mg / Cu = 2, and Mn / Cr = 3, the alloy exhibits the highest mechanical properties, with a yield strength of 524.9 MPa, a tensile strength of 552.3 MPa, and an elongation of 9.6%, far exceeding the performance of most 6000 series aluminum alloys currently available. In Examples 2 and 3, when the alloy composition is controlled at Mg / Si = 2.3–3.2, Mg / Cu = 2–3, and Mn / Cr = 3, the tensile strength of the alloys can reach over 470 MPa, and the elongation is also greater than 9%. However, in Comparative Examples 1 and 2, where the alloy composition deviates significantly, the tensile strength of the alloys is below 400 MPa, and the elongation also decreases to some extent. In Comparative Example 3, because only a single-stage aging process was used, the QP-II / GPB composite phase could not be obtained, and the vast majority of precipitated phases were β″ phases, resulting in low mechanical properties of the alloy.

[0045] Table 2 compares the tensile strength, yield strength, and elongation of the alloys in Examples 1 to 3 after peak aging and heat exposure at 200℃. It can be seen that in Example 1, with Mg / Si = 2.3, Mg / Cu = 2, and Mn / Cr = 3, the alloy exhibits the highest mechanical properties, with a yield strength of 360.8 MPa, a tensile strength of 407.6 MPa, and an elongation of 8.4%, far exceeding the performance of most 6000 series aluminum alloys currently available. In Examples 2 and 3, when the alloy composition is controlled at Mg / Si = 2.3~3.2, Mg / Cu = 2~3, and Mn / Cr = 3, the tensile strength of the alloys can reach over 360 MPa, and the elongation is also greater than 8%. However, in Comparative Examples 1 and 2, where the alloy composition deviates significantly, the tensile strength of the alloys is lower than 330 MPa, and the elongation also decreases to some extent. In Comparative Example 3, since only a single-stage aging process was used, the QP-II / GPB composite phase could not be obtained. The vast majority of the precipitated phases were β″ phases, resulting in low mechanical properties of the alloy at 200℃, which could not play a role in thermal stabilization.

[0046] Table 1. Tensile strength, yield strength, and elongation of alloys with different compositions at peak aging.

[0047] Table 2. Tensile strength, yield strength, and elongation of alloys with different compositions after peak aging and heat exposure at 200℃.

[0048] (2) High resolution Figure 1 This is an EBSD HAADF-STEM image of Example 1 after 100 hours of heat exposure at 200°C following peak aging of the alloy. From... Figure 2The QP2 phase (i.e., QP-II phase) was found to be coated with GPB regions at all interfaces, thus obtaining the QP-II / GPB composite phase. This was not found in Comparative Example 1 and Comparative Example 2.

[0049] (3) QP-II / GPB precipitates like Figure 2 As shown, the alloy obtained in Example 1 exhibits high-density nanoscale precipitates with cross-sectional dimensions approximately between 2 nm and 4 nm. Notably, the precipitates in Example 1 differ from the needle-like β″ phase found in traditional 6000 series aluminum alloys; the vast majority of precipitates in this alloy are lath-like or plate-like. Statistical comparison revealed that the proportion of the QP-II / GPB phase in the alloy can reach over 90%, thus significantly improving the age-hardening effect, precipitation kinetics, and thermal stability of the alloy.

[0050] like Figure 3 As shown, this is a bright-field TEM image of the nano-precipitates exposed by heat after peak aging of the alloy in Comparative Example 1. The precipitates in Comparative Example 1 are relatively large in size and have a low number density. Most of the precipitates are β″ phases. Therefore, the mechanical properties of the alloy are not high.

[0051] like Figure 4 As shown, this is a bright-field TEM image of the nano-precipitates exposed by heat after peak aging of the alloy in Comparative Example 2. The precipitates in Comparative Example 2 are relatively large in size and have a low number density. Most of the precipitates are β″ phases. Therefore, the mechanical properties of the alloy are not high.

[0052] like Figure 5 As shown, this is a bright-field TEM image of the nano-precipitates exposed by heat after peak aging of the alloy in Comparative Example 3. In Comparative Example 2, the precipitates are larger in size and have a lower number density. The vast majority of the precipitates are β″ phases. Therefore, the mechanical properties of the alloy are not high.

[0053] Example 4

[0054] A high-strength, high-thermal-stability aluminum alloy contains a QP-II phase, a QP-II / GPB composite phase, and a β" phase. The cross-sectional size of the QP-II phase is 2-10 nm, and the cross-sectional size of the β" phase is 2-20 nm. The QP-II / GPB composite phase is composed of GPB regions segregated at the QP-II interface. The QP-II / GPB composite phase accounts for about 85% of the total number of precipitates in the alloy, and the QP-II phase accounts for about 10% of the total number of precipitates in the alloy.

[0055] A high-strength, high-thermal-stability aluminum alloy, comprising 3.5 wt.% Mg, 1.4 wt.% Si, 1.59 wt.% Cu, 0.42 wt.% Mn, and 0.14 wt.% Cr.

[0056] The Mg / Si ratio is 2.5, the Mg / Cu ratio is 2.2, and the Mn / Cr ratio is 3.

[0057] A method for preparing a high-strength, high-thermal-stability aluminum alloy includes the following steps: Step 1: Casting the aluminum alloy; using 99.98% industrial pure aluminum, pure Mg, Al-Si master alloy, Al-Cu master alloy, Al-Mn master alloy, and Al-Cr master alloy as raw materials, the alloy is cast using semi-continuous casting at a casting temperature of 720℃ and a cooling rate of 70mm / min. The cast ingot has a diameter of 178mm and a length of 2 meters. A small piece is cut along the casting direction, with dimensions of 70×35×20mm (length×width×height), and then subjected to homogenization heat treatment; Step 2: Homogenize the cast aluminum alloy by heating it at 60℃ / h to 550℃, holding it at that temperature for 8 hours, and then air-cooling it to room temperature. Step 3: The homogenized heat-treated aluminum alloy is subjected to pressure deformation to obtain rolled profile. The homogenized material is then milled and hot-rolled in six passes at 500℃, with each hot rolling amount being 7mm, reducing the thickness from 48mm to 6mm. The hot rolling exit temperature is 390℃. Subsequently, it is cold-rolled from 6mm to 4mm, followed by intermediate annealing at 420℃ for 3 hours, and then cold-rolled in two more passes to the final thickness of 1mm, with each pass removing 2mm, to obtain rolled profile. Step 4: The rolled profile is first solution treated and then water quenched to room temperature; the solution temperature is 570℃ and the holding time is 100min; the quenching water temperature is 50℃ and the quenching transfer time interval is less than 30s. Step 5: Perform three levels of artificial aging treatment: Level 1 artificial aging temperature is 180℃ and time is 15 hours; Level 2 artificial aging temperature is 210℃ and time is 8 hours; Level 3 artificial aging temperature is 165℃ and time is 4 hours.

[0058] This embodiment describes the application of a high-strength, high-thermal-stability aluminum alloy in the manufacture of profiles, plates, and forgings used in aerospace, defense, high-speed rail, automobiles, bicycles, pressure vessels, construction, power, and photovoltaic fields. Specifically, it includes applications in high-temperature working materials, such as automobile engine compartments, rail transit braking systems, and new energy vehicle wiring materials.

[0059] A high-strength, high-thermal-stability aluminum alloy exhibits the following properties at room temperature: tensile strength of 540 MPa, yield strength of 519 MPa, and elongation of 9.3%. At 200°C, the alloy achieves tensile strength of 400 MPa, yield strength of 350 MPa, and elongation of 8.2%.

[0060] Example 5

[0061] A high-strength, high-thermal-stability aluminum alloy contains a QP-II phase, a QP-II / GPB composite phase, and a β" phase. The cross-sectional size of the QP-II phase is 2-10 nm, and the cross-sectional size of the β" phase is 2-20 nm. The QP-II / GPB composite phase is composed of GPB regions segregated at the QP-II interface. The QP-II / GPB composite phase accounts for about 70% of the total number of precipitates in the alloy, and the QP-II phase accounts for about 20% of the total number of precipitates in the alloy.

[0062] A high-strength, high-thermal-stability aluminum alloy, comprising 1 wt.% Mg, 0.43 wt.% Si, 0.5 wt.% Cu, 0.12 wt.% Mn, and 0.04 wt.% Cr.

[0063] The Mg / Si ratio is 2.3, the Mg / Cu ratio is 2, and the Mn / Cr ratio is 3.

[0064] A method for preparing a high-strength, high-thermal-stability aluminum alloy includes the following steps: Step 1: Casting the aluminum alloy; using 99.98% industrial pure aluminum, pure Mg, Al-Si master alloy, Al-Cu master alloy, Al-Mn master alloy, and Al-Cr master alloy as raw materials, the alloy is cast using semi-continuous casting at a casting temperature of 690℃ and a cooling rate of 50mm / min. The cast ingot has a diameter of 178mm and a length of 2 meters. A small piece is cut along the casting direction, with dimensions of 70×35×20mm (length×width×height), and then subjected to homogenization heat treatment; Step 2: Homogenize the cast aluminum alloy by heating it to 560℃ at a rate of 30℃ / h, holding it at that temperature for 4 hours, and then air-cooling it to room temperature. Step 3: The homogenized heat-treated aluminum alloy is subjected to pressure deformation to obtain rolled profiles. The homogenized material is then milled and hot-rolled in six passes at 480℃, with each hot rolling amount being 7mm, reducing the thickness from 48mm to 6mm. The hot rolling exit temperature is 350℃. Subsequently, it is cold-rolled from 6mm to 4mm, followed by intermediate annealing at 350℃ for 1 hour, and then cold-rolled in two more passes to the final thickness of 1mm, with each pass removing 2mm, to obtain rolled profiles. Step 4: The rolled profile is first solution treated and then water quenched to room temperature; the solution temperature is 520℃ and the holding time is 10min; the quenching water temperature is 70℃ and the quenching transfer time interval is less than 30s. Step 5: Perform three levels of artificial aging treatment: Level 1 artificial aging temperature is 170℃ and time is 1 hour; Level 2 artificial aging temperature is 180℃ and time is 3 hours; Level 3 artificial aging temperature is 150℃ and time is 1 hour.

[0065] This embodiment describes the application of a high-strength, high-thermal-stability aluminum alloy in the manufacture of profiles, plates, and forgings used in aerospace, defense, high-speed rail, automobiles, bicycles, pressure vessels, construction, power, and photovoltaic fields. Specifically, it includes applications in high-temperature working materials, such as automobile engine compartments, rail transit braking systems, and new energy vehicle wiring materials.

[0066] A high-strength, high-thermal-stability aluminum alloy exhibits the following properties at room temperature: tensile strength of 470 MPa, yield strength of 430 MPa, and elongation of 9.1%. At 200°C, the alloy achieves tensile strength of 365 MPa, yield strength of 300 MPa, and elongation of 8.0%.

[0067] Example 6

[0068] A high-strength, high-thermal-stability aluminum alloy contains a QP-II phase, a QP-II / GPB composite phase, and a β" phase. The cross-sectional size of the QP-II phase is 2-10 nm, and the cross-sectional size of the β" phase is 2-20 nm. The QP-II / GPB composite phase is composed of GPB regions segregated at the QP-II interface. The QP-II / GPB composite phase accounts for about 90% of the total number of precipitates in the alloy, and the QP-II phase accounts for about 10% of the total number of precipitates in the alloy.

[0069] A high-strength, high-thermal-stability aluminum alloy, comprising 4 wt.% Mg, 1.33 wt.% Si, 2.0 wt.% Cu, 0.09 wt.% Mn, and 0.03 wt.% Cr.

[0070] The ratio of Mg to Si is 3, the ratio of Mg to Cu is 2, and the ratio of Mn to Cr is 3.

[0071] A method for preparing a high-strength, high-thermal-stability aluminum alloy includes the following steps: Step 1: Casting the aluminum alloy; using 99.98% industrial pure aluminum, pure Mg, Al-Si master alloy, Al-Cu master alloy, Al-Mn master alloy, and Al-Cr master alloy as raw materials, the alloy is cast using semi-continuous casting at a casting temperature of 750℃ and a cooling rate of 90mm / min. The cast ingot has a diameter of 178mm and a length of 2 meters. A small piece is cut along the casting direction, with dimensions of 70×35×20mm (length×width×height), and then subjected to homogenization heat treatment; Step 2: Homogenize the cast aluminum alloy by heating it to 570℃ at a rate of 100℃ / h, holding it at that temperature for 10h, and then air-cooling it to room temperature. Step 3: The homogenized heat-treated aluminum alloy is subjected to pressure deformation to obtain rolled profile. The homogenized material is then milled and hot-rolled in six passes at 520℃, with each hot rolling amount being 7mm, reducing the thickness from 48mm to 6mm. The hot rolling exit temperature is 400℃. Subsequently, it is cold-rolled from 6mm to 4mm, followed by intermediate annealing at 430℃ for 5 hours, and then cold-rolled in two more passes to the final thickness of 1mm, with each pass removing 2mm, to obtain rolled profile. Step 4: The rolled profile is first solution treated and then water quenched to room temperature; the solution temperature is 580℃ and the holding time is 6h; the quenching water temperature is 10℃ and the quenching transfer time interval is less than 30s. Step 5: Perform three levels of artificial aging treatment: Level 1 artificial aging temperature is 175℃ and time is 20h; Level 2 artificial aging temperature is 220℃ and time is 10h; Level 3 artificial aging temperature is 170℃ and time is 5h.

[0072] This embodiment describes the application of a high-strength, high-thermal-stability aluminum alloy in the manufacture of profiles, plates, and forgings used in aerospace, defense, high-speed rail, automobiles, bicycles, pressure vessels, construction, power, and photovoltaic fields. Specifically, it includes applications in high-temperature working materials, such as automobile engine compartments, rail transit braking systems, and new energy vehicle wiring materials.

[0073] A high-strength, high-thermal-stability aluminum alloy exhibits the following properties at room temperature: tensile strength of 538 MPa, yield strength of 517 MPa, and elongation of 10.0%. At 200°C, the tensile strength reaches 391 MPa, yield strength of 354 MPa, and elongation of 8.3%.

[0074] It should be understood that, in order to simplify this disclosure and aid in understanding one or more of the various aspects of the invention, features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof in the above description of exemplary embodiments of the invention. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than expressly recited in each claim. Rather, as reflected in the claims, inventive aspects lie in fewer than all the features of the foregoingly disclosed embodiments. Therefore, the claims, following the detailed description, are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of the invention.

[0075] Although the invention has been described with reference to a limited number of embodiments, those skilled in the art will understand from the foregoing description that other embodiments are conceivable within the scope of the invention described herein. Furthermore, it should be noted that the language used in this specification has been chosen primarily for readability and instructional purposes, and not for the purpose of interpreting or limiting the subject matter of the invention. Therefore, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the invention is illustrative and not restrictive, and the scope of the invention is defined by the appended claims.

[0076] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-strength, high-thermal-stability aluminum alloy, characterized in that, The alloy contains QP-II phase, QP-II / GPB composite phase, and β" phase; the cross-sectional size of QP-II phase is 2-10 nm, the cross-sectional size of β" phase is 2-20 nm, and the QP-II / GPB composite phase is composed of GPB regions segregated on the QP-II interface; the QP-II / GPB composite phase accounts for 70-90% of the total number of precipitates in the alloy, and the QP-II phase accounts for 10-20% of the total number of precipitates in the alloy.

2. The high-strength, high-thermal-stability aluminum alloy according to claim 1, characterized in that, The aluminum alloy is an Al-Mg-Si series aluminum alloy, with Mg content of 1-4 wt.%, Si content of 0.43-1.4 wt.%, Cu content of 0.5-2.0 wt.%, Mn content of 0.09-0.5 wt.%, and Cr content of 0.03-0.17 wt.%.

3. The high-strength, high-thermal-stability aluminum alloy according to claim 1, characterized in that, The Mg / Si ratio is 2.3~3.2, the Mg / Cu ratio is 2~3, and the Mn / Cr ratio is 3.

4. The high-strength, high-thermal-stability aluminum alloy according to claim 1, characterized in that, At room temperature, the alloy has a tensile strength of over 470 MPa, a yield strength of over 429 MPa, and an elongation of over 9%; at 200℃, the alloy has a tensile strength of over 360 MPa, a yield strength of over 290 MPa, and an elongation of over 8%.

5. A method for preparing a high-strength, high-thermal-stability aluminum alloy according to any one of claims 1 to 4, characterized in that, Includes the following steps: Step 1: Casting aluminum alloy; Step 2: Homogenize the cast aluminum alloy with heat treatment. Step 3: The homogenized heat-treated aluminum alloy is subjected to pressure deformation to obtain rolled profiles. The pressure deformation temperature is 350℃~500℃, and the deformation rate is 0.001~10 s. -1 ; Step 4: The rolled profile is first solution treated and then water quenched to room temperature; Step 5: Perform three levels of artificial aging treatment: Level 1 artificial aging temperature is 170-180℃, time is 1h-20h; Level 2 artificial aging temperature is 180-220℃, time is 3-10h; Level 3 artificial aging temperature is 150-170℃, time is 1-5h.

6. The preparation method according to claim 5, characterized in that, In step one, the method for casting aluminum alloy is as follows: using 99.98% industrial pure aluminum, pure Mg, Al-Si master alloy, Al-Cu master alloy, Al-Mn master alloy and Al-Cr master alloy as raw materials, the alloy is completed by semi-continuous casting, the casting temperature is 690℃~750℃, and the cooling rate is 50~90mm / min.

7. The preparation method according to claim 5, characterized in that, In step two, the homogenization heat treatment process is as follows: heat up to 550-570℃ at a rate of 30-100℃ / h, hold for 4-10h, and then air cool to room temperature.

8. The preparation method according to claim 5, characterized in that, In step three, the pressure deformation process is as follows: after homogenization, the material is cut and milled, and then hot rolled in six passes at 480℃~520℃, with each hot rolling amount being 7mm, reducing the thickness from 48mm to 6mm. The hot rolling exit temperature is 350-400℃. Then, it is cold rolled from 6mm to 4mm, followed by intermediate annealing at 350℃~430℃ for 1-5 hours, and then rolled in two more cold rolling passes to the final thickness of 1mm, with each pass removing two 2mm sections to obtain the rolled profile.

9. The preparation method according to claim 5, characterized in that, In step four, the solution temperature is 520℃~580℃, the holding time is 10min~6h, the quenching water temperature is 10℃~70℃, and the quenching transfer time interval is less than 30s.

10. The application of a high-strength, high-thermal-stability aluminum alloy according to any one of claims 1 to 4 in the manufacture of profiles, plates, and forgings used in aerospace, defense, high-speed rail, automobiles, bicycles, pressure vessels, construction, power, and photovoltaic fields, characterized in that... This includes applications in high-temperature materials, such as automotive engine compartments, rail transit braking systems, and wiring materials for new energy vehicles.

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