Preparation method of 7108 aluminum alloy based on joule heat solid solution and artificial aging and 7108 aluminum alloy

Abstract

The application discloses a 7108 aluminum alloy preparation method based on joule heat solid solution and artificial aging and a 7108 aluminum alloy, and belongs to the technical field of aluminum alloy heat treatment. The application firstly carries out solid solution treatment on the artificial aging state 7108 aluminum alloy by using a joule heat device, makes soluble strengthening phases in the alloy dissolve into an aluminum matrix through rapid heating, makes solute atoms in excess remain in the aluminum matrix to form a supersaturated solid solution, then carries out artificial aging treatment, makes the solute atoms in excess in the alloy precipitate in the form of dispersed distribution precipitated phase particles, and thus the strength of the aluminum alloy is improved, and the plasticity of the aluminum alloy is ensured.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy heat treatment technology, specifically to a method for preparing 7108 aluminum alloy based on Joule heat solution and artificial aging, and the 7108 aluminum alloy itself. Background Technology

[0002] As automobiles become increasingly heavier due to improvements in safety, luxury, and performance, the industry still faces ever-tighter fuel efficiency and emission standards. The application of aluminum-based automotive components is considered one of the most promising solutions to these evolving challenges. To further enhance the formability and ductility of aluminum and its alloys, combining high-strength aluminum alloys with appropriate design is crucial for the application of aluminum-based materials in safe and impact-resistant automotive parts. Focusing on lightweighting recommends the use of higher-strength aluminum alloys from the 7XXX series. These alloys are mostly composed of Al-Zn-Mg or Al-Zn-Mg-Cu, and these alloying elements improve mechanical strength. 7XXX series alloys possess phases in equilibrium with the aluminum-rich matrix, exhibiting both solid solution and precipitation capabilities. The most common phases in this system are the η phase (MgZn2), T phase (Al2Mg3Zn3), and β phase (Al3Mg5). Adding Mg to Al-Zn alloys significantly improves the mechanical strength of the system, especially in the 3-7.5% Zn range, where it combines with Mg to form MgZn2 (η phase). The MgZn2 precipitate is the primary intermetallic compound for age hardening in these alloys. These 7XXX series alloys possess very high ultimate tensile strength. However, this high strength is accompanied by relatively low elongation at break. One method to modify the mechanical properties of 7XXX series alloys is to employ appropriate heat treatment processes.

[0003] Traditional heat treatment processes for aluminum alloys include solution treatment and aging treatment. Due to equipment limitations, the solution treatment stage often requires prolonged heating and holding times. However, this process significantly increases production time and costs, and controlling the solution temperature is difficult. Lower solution temperatures fail to allow alloying elements to fully dissolve, forming a supersaturated solid solution, while higher temperatures can cause overheating, both of which reduce the actual strength of the aluminum alloy. Summary of the Invention

[0004] To address the problem in existing technologies that it is difficult to improve the strength of 7108 aluminum alloy and maintain good plasticity in a short time, the present invention aims to provide a method for preparing 7108 aluminum alloy based on Joule thermal solution treatment and artificial aging, and a 7108 aluminum alloy thereof. This method dissolves the soluble strengthening phase in the 7108 aluminum alloy into the aluminum matrix through solution treatment, and further obtains a 7108 aluminum alloy with both high strength and better elongation at break through artificial aging treatment.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing 7108 aluminum alloy based on Joule thermal solution and artificial aging, the method comprising the following steps: (1) Prepare artificially aged 7108 aluminum alloy as raw material: (2) Joule heat solution treatment: The artificially aged 7108 aluminum alloy in step (1) is subjected to solution treatment using ultra-fast high temperature sintering technology (UHS) to dissolve the soluble strengthening phase in the 7108 aluminum alloy into the aluminum matrix and obtain the solution-treated 7108 aluminum alloy. (3) Artificial aging treatment: The 7108 aluminum alloy after solution treatment in step (2) is subjected to artificial aging treatment so that the supersaturated solute atoms in the 7108 aluminum alloy precipitate in the form of dispersed precipitate phase particles, and the 7108 aluminum alloy after artificial aging is obtained.

[0006] Further, in step (1), the chemical composition of the artificially aged 7108 aluminum alloy by weight percentage is: Mg 0.7-1.4%, Zn 4.5-5.5%, Zr 0.12-0.25%, and aluminum as the balance.

[0007] Furthermore, in step (2), during the solution treatment process, the solution temperature is 485-520℃ and the holding time is 35-70s.

[0008] Furthermore, in step (2), during the solution treatment process, the heating is carried out by furnace heating at a rate of 160-170℃ / s; and the cooling is carried out by water cooling.

[0009] Further, in step (2), the ultra-fast high-temperature sintering technology (UHS) is carried out using a Joule heating device (ultra-fast high-temperature sintering furnace). Specifically, the artificially aged 7108 aluminum alloy in step (1) is wrapped with electrically conductive carbon materials (graphite sheets, carbon felt, carbon paper, etc.). Then, the electrically conductive carbon material wrapped with aluminum alloy is placed in the center of the heater of the ultra-fast high-temperature sintering furnace to ensure uniform heating during the heating process. Then, the furnace door is closed, and argon gas is repeatedly introduced 3-5 times to ensure that there is no air in the furnace to prevent high-temperature oxidation of the furnace components.

[0010] Furthermore, in step (3), during the artificial aging process, the aging temperature is 120-160℃ and the heat preservation time is 8-12h.

[0011] Furthermore, in step (3), during the artificial aging process, the heating is carried out by furnace heating at a rate of 0.5-1.5℃ / min; and the cooling is carried out by water cooling.

[0012] Furthermore, in the microstructure of the artificially aged 7108 aluminum alloy obtained in step (3), the precipitated phases include the GP region and the η phase.

[0013] Furthermore, the 7108 aluminum alloy after artificial aging has a tensile strength of 360-400 MPa, a yield strength of 280-310 MPa, and an elongation of 11-14% at room temperature.

[0014] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1. This invention involves solution treatment of 7108 aluminum alloy using a Joule heating device to dissolve the alloying elements and allow them to enter the aluminum matrix, forming a metastable, homogeneous, supersaturated solid solution. Subsequent artificial aging treatment promotes the formation of fine, dense precipitate nucleation sites, causing the supersaturated solute atoms to precipitate as dispersed precipitate particles. These fine, dispersed precipitates effectively hinder dislocation movement within the crystal, thereby increasing the strength of the aluminum alloy. Simultaneously, the small size of the precipitates alleviates stress concentration during deformation, ensuring the alloy's ductility.

[0015] 2. This invention employs ultra-fast high-temperature sintering (UHS) technology for solution treatment of aluminum alloys. Through the resistance heating effect of carbon conductors (such as graphene foam, graphite sheets, carbon felt, and carbon paper), extreme heating rates (up to 500℃ / s) and precise temperature control (±5℃) can be achieved. The Joule heating device (also known as the Joule ultra-fast heating device or ultra-fast high-temperature sintering furnace) is the core equipment for realizing ultra-fast high-temperature sintering (UHS) technology. Utilizing the Joule heating principle, it can achieve millisecond-level ultra-high temperatures (up to 3000℃) and extremely rapid heating and cooling.

[0016] 2. After Joule heat solution treatment and artificial aging, the 7108 aluminum alloy of this invention exhibits a tensile strength of 360-400 MPa, a yield strength of 280-310 MPa, and an elongation of 11-14% at room temperature. Compared to traditional solution aging methods, the alloy of this invention, after solution treatment and artificial aging using a Joule heat device, shows improved strength and hardness while significantly reducing the required heat treatment time. Attached Figure Description

[0017] Figure 1 The diagram shows the precipitated phase microstructure of the 7108 aluminum alloy after solution treatment and artificial aging using a Joule heating device in Example 1.

[0018] Figure 2 The diagram shows the precipitate microstructure of the 7108 aluminum alloy after solution treatment and artificial aging in a muffle furnace in Comparative Example 2.

[0019] Figure 3 The image shows the tensile fracture surface morphology of the 7108 aluminum alloy after solution treatment and artificial aging using a Joule heating device in Example 1. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments, so that those skilled in the art can better understand and implement the present invention, but the embodiments are not intended to limit the present invention.

[0021] This invention provides a method for Joule hot solution treatment and artificial aging of 7108 aluminum alloy, comprising the following steps: (1) Prepare artificially aged 7108 aluminum alloy. The chemical composition of the aluminum alloy by weight percentage is: Mg 0.7-1.4wt%, Zn 4.5-5.5wt%, Zr 0.12-0.25wt%, with aluminum as the balance.

[0022] (2) Joule heat solution treatment: The artificially aged 7108 aluminum alloy in step (1) is subjected to solution treatment using ultra-fast high temperature sintering technology (UHS) so that the soluble strengthening phase in the 7108 aluminum alloy dissolves into the aluminum matrix and the 7108 aluminum alloy is obtained after solution treatment by a Joule heating device. Specifically, the 7108 aluminum alloy is placed in a Joule heating device at room temperature (cavity temperature) and heated to 485-520℃ at a heating rate of 160-170℃ / s, held for 35-70s, and then cooled by water cooling.

[0023] (3) Artificial aging treatment: The solution-treated 7108 aluminum alloy is subjected to artificial aging treatment so that the supersaturated solute atoms in the 7108 aluminum alloy precipitate in the form of diffusely distributed precipitate particles, and the artificially aged 7108 aluminum alloy is obtained. The specific steps are as follows: the solution-treated 7108 aluminum alloy is placed in a heat treatment furnace after water cooling using a Joule heating device, and the temperature is increased from room temperature to 120-160℃ at a heating rate of 1℃ / min, held for 8-12h, and then taken out after water cooling.

[0024] Based on the above method, a Joule heating device is used to perform solid solution treatment, causing the alloying elements in the aluminum alloy to dissolve and enter the aluminum matrix, forming a metastable, homogeneous, supersaturated solid solution. Then, artificial aging treatment promotes the formation of fine, dense precipitate nucleation sites, and causes the supersaturated solute atoms to precipitate as diffusely distributed precipitate particles. These fine, dispersed precipitates effectively hinder dislocation movement within the crystal, thereby increasing the strength of the aluminum alloy. Simultaneously, the small size of the precipitates alleviates stress concentration during deformation, thus ensuring the alloy's ductility.

[0025] During the solution treatment stage, the heating time is controlled within 3-5 seconds and the holding time is controlled within 30-70 seconds, which greatly reduces the long heating and holding time required in the traditional solution treatment stage. Example 1:

[0026] This embodiment provides a method for preparing 7108 aluminum alloy based on Joule thermal solution and artificial aging, including the following steps: (1) Prepare artificially aged 7108 aluminum alloy. The chemical composition of the aluminum alloy by weight percentage is: Mg 0.8wt%, Zn 4.5wt%, Zr 0.16wt%, with aluminum as the balance.

[0027] (2) Solution treatment using a Joule heating device: The artificially aged 7108 aluminum alloy is placed in a Joule heating device and heated from room temperature to 500°C at a heating rate of 170°C / s, held for 50s, and then cooled by water.

[0028] (3) Artificial aging treatment: After the 7108 aluminum alloy was solution treated with a Joule heating device, it was placed in a heat treatment furnace after being cooled by water. The temperature was increased from room temperature to 140°C at a heating rate of 1°C / min, held for 10 hours, and then cooled by water before being taken out.

[0029] The precipitated phases of the 7108 aluminum alloy obtained after the artificial aging treatment in step (3) of this embodiment were tested, and the results are as follows: Figure 1 As shown, the precipitated phases are fine and dispersed, with a diameter of only about 5 μm, and are uniformly distributed in the aluminum matrix. Judging from their morphology, the precipitated phases include GP zones and η phases. Microhardness and tensile tests were performed on the artificially aged 7108 aluminum alloy obtained in this embodiment, and the test results are shown in Table 1. It can be seen that the alloy obtained in this embodiment has excellent hardness, strength, and plasticity. Specifically, the microhardness at room temperature is 148.1 HV, the tensile strength is 400.52 MPa, the yield strength is 301.06 MPa, and the elongation is 15.1%. The fracture morphology after tensile testing is shown in Table 1. Figure 3 As shown, its dimples are small and uniform, and it also has a typical dissociation surface morphology. Its fracture mode is a combination of ductile and brittle fracture.

[0030] Comparative Example 1: This example provides a method for preparing 7108 aluminum alloy based on Joule hot solution and artificial aging, including the following steps: (1) Prepare artificially aged 7108 aluminum alloy. The chemical composition of the aluminum alloy by weight percentage is: Mg 0.8wt%, Zn 4.5wt%, Zr 0.16wt%, with aluminum as the balance.

[0031] (2) Solution treatment using a Joule heating device: The artificially aged 7108 aluminum alloy is placed in a Joule heating device and heated from room temperature to 480°C at a heating rate of 160°C / s, held for 30s, and then cooled by water.

[0032] (3) Artificial aging treatment: After the 7108 aluminum alloy was solution treated with a Joule heating device, it was placed in a heat treatment furnace after being cooled by water. The temperature was increased from room temperature to 140°C at a rate of 1°C / min. After holding at the temperature for 10 hours, it was cooled by water and then taken out.

[0033] Microhardness and tensile tests were performed on the 7108 aluminum alloy obtained after artificial aging treatment in step (3) of this comparative example. The test results are shown in Table 1. It can be seen that although Joule heating device was also used for solution treatment, the alloy obtained in this comparative example has poor hardness, strength and plasticity due to unsuitable treatment parameters. The microhardness at room temperature is 125.1 HV, the tensile strength is 364.7 MPa, the yield strength is 282.3 MPa and the elongation is 11.2%. Example 2:

[0034] This embodiment provides a method for preparing 7108 aluminum alloy based on Joule thermal solution and artificial aging, including the following steps: (1) Prepare artificially aged 7108 aluminum alloy. The chemical composition of the aluminum alloy by weight percentage is: Mg 0.8wt%, Zn 4.5wt%, Zr 0.16wt%, with aluminum as the balance.

[0035] (2) Solution treatment using a Joule heating device: The artificially aged 7108 aluminum alloy was placed in a Joule heating device and heated from room temperature to 520°C at a heating rate of 170°C / s, held for 70s, and then cooled down by water.

[0036] (3) Artificial aging treatment: After the 7108 aluminum alloy was solution treated with a Joule heating device, it was placed in a heat treatment furnace after being cooled by water. The temperature was increased from room temperature to 140°C at a heating rate of 1°C / min, held for 10 hours, and then cooled by water before being taken out.

[0037] The 7108 aluminum alloy obtained after artificial aging treatment in step (3) of this embodiment was subjected to microhardness test and tensile test. The test results are shown in Table 1. It can be seen that the alloy obtained in this embodiment has good hardness, strength and plasticity. The microhardness at room temperature is 136.1 HV, the tensile strength is 384.67 MPa, the yield strength is 313.4 MPa and the elongation is 14.29%.

[0038] Comparative Example 2: This example provides a method for preparing 7108 aluminum alloy using muffle furnace solution treatment and artificial aging, including the following steps: (1) Prepare artificially aged 7108 aluminum alloy. The chemical composition of the aluminum alloy by weight percentage is: Mg 0.8wt%, Zn 4.5wt%, Zr 0.16wt%, with aluminum as the balance.

[0039] (2) Solution treatment: Place the 7108 aluminum alloy in a muffle furnace and heat it from room temperature to 500°C at a rate of 30°C / min. Hold it at that temperature for 30 minutes and then cool it down with water.

[0040] (3) Artificial aging treatment: After the solution-treated 7108 aluminum alloy is cooled by water, it is placed in a muffle furnace and heated from room temperature to 140°C at a heating rate of 1°C / min. The temperature is held for 10 hours and then cooled by water before being taken out.

[0041] The precipitates of the artificially aged 7108 aluminum alloy obtained in this comparative example are as follows: Figure 2 As shown, there are relatively few precipitated phases, and their distribution in the aluminum matrix is ​​uneven. Microhardness and tensile tests were performed on the artificially aged 7108 aluminum alloy obtained in this comparative example. The test results are shown in Table 1. It can be seen that the alloy obtained in this comparative example has lower hardness, strength, and plasticity than that of Example 1. At room temperature, the microhardness is 137.4 HV, the tensile strength is 373.67 MPa, the yield strength is 289.4 MPa, and the elongation is 10.19%.

[0042] Comparative Example 3: This comparative example provides a solution treatment and artificial aging method for 7108 aluminum alloy, including the following steps: Solution treatment: Place the 7108 aluminum alloy in a muffle furnace and heat it from room temperature to 470°C at a rate of 30°C / min, and hold it for 30 minutes.

[0043] Artificial aging treatment: After solution treatment, the 7108 aluminum alloy is cooled by water and placed in a muffle furnace. The temperature is increased from room temperature to 140°C at a rate of 1°C / min and held for 10 hours.

[0044] Microhardness and tensile tests were performed on the 7108 aluminum alloy obtained in this comparative example after solution treatment and artificial aging. The test results are shown in Table 1. It can be seen that the alloy obtained in this comparative example has poor hardness and strength, but its plasticity is higher than that of Example 1. The microhardness at room temperature is 113.5 HV, the tensile strength is 320.27 MPa, the yield strength is 251.83 MPa, and the elongation is 18.31%.

[0045] Comparative Example 4: This comparative example provides a method for preparing 7108 aluminum alloy based on muffle furnace solution treatment and artificial aging, including the following steps: (1) Prepare artificially aged 7108 aluminum alloy. The chemical composition of the aluminum alloy by weight percentage is: Mg 0.8wt%, Zn 4.5wt%, Zr 0.16wt%, with aluminum as the balance.

[0046] (2) Solution treatment: The artificially aged 7108 aluminum alloy was placed in a muffle furnace and heated from room temperature to 480°C at a heating rate of 30°C / min. The temperature was held for 30 min and then cooled by water.

[0047] (3) Artificial aging treatment: After the solution-treated 7108 aluminum alloy is cooled by water, it is placed in a muffle furnace and heated from room temperature to 140°C at a heating rate of 1°C / min. The temperature is held for 10 hours and then cooled by water before being taken out.

[0048] Microhardness and tensile tests were performed on the 7108 aluminum alloy obtained by artificial aging treatment in this comparative example. The test results are shown in Table 1. It can be seen that the alloy obtained by this comparative example has a microhardness of 129.7 HV, a tensile strength of 351.73 MPa, a yield strength of 262.47 MPa, and an elongation of 16.11% at room temperature.

[0049] Comparative Example 5: This comparative example provides a method for preparing 7108 aluminum alloy based on muffle furnace solution treatment and artificial aging, including the following steps: (1) Prepare artificially aged 7108 aluminum alloy. The chemical composition of the aluminum alloy by weight percentage is: Mg 0.8wt%, Zn 4.5wt%, Zr 0.16wt%, with aluminum as the balance.

[0050] (2) Solution treatment: The artificially aged 7108 aluminum alloy was placed in a muffle furnace and heated from room temperature to 490°C at a heating rate of 30°C / min. The temperature was held for 30 min and then cooled by water.

[0051] (3) Artificial aging treatment: After the solution-treated 7108 aluminum alloy is cooled by water, it is placed in a muffle furnace and heated from room temperature to 140°C at a heating rate of 1°C / min. The temperature is held for 10 hours and then cooled by water before being taken out.

[0052] Microhardness and tensile tests were performed on the 7108 aluminum alloy obtained by artificial aging treatment in this comparative example. The test results are shown in Table 1. It can be seen that the alloy obtained by this comparative example has a microhardness of 124.4 HV, a tensile strength of 369.16 MPa, a yield strength of 268.95 MPa, and an elongation of 15.13% at room temperature.

[0053] Comparative Example 6: This comparative example provides a method for preparing 7108 aluminum alloy based on muffle furnace solution treatment and artificial aging, including the following steps: (1) Prepare artificially aged 7108 aluminum alloy. The chemical composition of the aluminum alloy by weight percentage is: Mg 0.8wt%, Zn 4.5wt%, Zr 0.16wt%, with aluminum as the balance.

[0054] (2) Solution treatment: Place the 7108 aluminum alloy in a muffle furnace and heat it from room temperature to 510°C at a rate of 30°C / min. Hold it at that temperature for 30 minutes and then cool it down with water.

[0055] (3) Artificial aging treatment: After the solution-treated 7108 aluminum alloy is cooled by water, it is placed in a muffle furnace and heated from room temperature to 140°C at a heating rate of 1°C / min. The temperature is held for 10 hours and then cooled by water before being taken out.

[0056] Microhardness and tensile tests were performed on the 7108 aluminum alloy obtained in this comparative example after artificial aging treatment. The test results are shown in Table 1. It can be seen that the alloy obtained in this comparative example has a microhardness of 132.4 HV, a tensile strength of 356.06 MPa, a yield strength of 244.61 MPa, and an elongation of 16.73% at room temperature.

[0057] Comparative Example 7: This comparative example provides a method for preparing 7108 aluminum alloy based on muffle furnace solution treatment and artificial aging, including the following steps: (1) Prepare artificially aged 7108 aluminum alloy. The chemical composition of the aluminum alloy by weight percentage is: Mg 0.8wt%, Zn 4.5wt%, Zr 0.16wt%, with aluminum as the balance.

[0058] (2) Solution treatment: The artificially aged 7108 aluminum alloy was placed in a muffle furnace and heated from room temperature to 520°C at a heating rate of 30°C / min. The temperature was held for 30 min and then cooled by water.

[0059] (3) Artificial aging treatment: After the solution-treated 7108 aluminum alloy is cooled by water, it is placed in a muffle furnace and heated from room temperature to 140°C at a heating rate of 1°C / min. The temperature is held for 10 hours and then cooled by water before being taken out.

[0060] Microhardness and tensile tests were performed on the 7108 aluminum alloy obtained by artificial aging treatment in this comparative example. The test results are shown in Table 1. It can be seen that the alloy obtained by this comparative example has a microhardness of 118.5 HV, a tensile strength of 345.89 MPa, a yield strength of 235.37 MPa, and an elongation of 14.55% at room temperature.

[0061] The alloys prepared in the above embodiments and comparative examples were tested for microhardness and tensile strength. Specifically: Microhardness testing was conducted using an HV-3000B microhardness tester with a loading force of 300 N and a holding time of 15 s. Tensile strength testing was performed using an Instron 5982 electronic universal testing machine at a tensile speed of 0.6 mm / min. The test results are summarized in Table 1.

[0062] Table 1. Strength test results of alloys prepared in the examples and comparative examples. sample Microhardness (HV) Tensile strength (MPa) Yield strength (MPa) Elongation (%) Example 1 148.1 400.52 301.06 15.1 Comparative Example 1 125.1 364.7 282.3 11.2 Example 2 136.1 384.67 313.4 14.29 Comparative Example 2 137.4 373.67 289.4 10.19 Comparative Example 3 113.5 320.27 251.83 18.31 Comparative Example 4 129.7 351.73 262.47 16.11 Comparative Example 5 124.4 369.16 268.95 15.13 Comparative Example 6 132.4 356.06 244.61 16.73 Comparative Example 7 118.5 345.89 235.37 14.55 In summary, compared with traditional solution treatment and artificial aging processes, this invention achieves rapid heating and holding through a Joule heating device, effectively improving the rapid strengthening capability of 7108 aluminum alloy in a short time, and also exhibiting high strength, hardness, and plasticity.

[0063] The above description is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing 7108 aluminum alloy based on Joule thermal solution and artificial aging, characterized in that: The method includes the following steps: (1) Prepare artificially aged 7108 aluminum alloy as raw material: (2) Joule heat solution treatment: The artificially aged 7108 aluminum alloy in step (1) is subjected to solution treatment using ultra-fast high temperature sintering technology (UHS) to dissolve the soluble strengthening phase in the 7108 aluminum alloy into the aluminum matrix and obtain the solution-treated 7108 aluminum alloy. (3) Artificial aging treatment: The 7108 aluminum alloy after solution treatment in step (2) is subjected to artificial aging treatment so that the supersaturated solute atoms in the 7108 aluminum alloy precipitate in the form of dispersed precipitate phase particles, and the 7108 aluminum alloy after artificial aging is obtained.

2. The method for preparing 7108 aluminum alloy based on Joule thermal solution and artificial aging according to claim 1, characterized in that: In step (1), the chemical composition of the artificially aged 7108 aluminum alloy, by weight percentage, is as follows: Mg: 0.7-1.4%, Zn: 4.5-5.5%, Zr: 0.12-0.25%, with aluminum as the balance.

3. The method for preparing 7108 aluminum alloy based on Joule thermal solution and artificial aging according to claim 1, characterized in that: In step (2), the solution treatment process is carried out at a temperature of 485-520℃ and a holding time of 35-70s.

4. The method for preparing 7108 aluminum alloy based on Joule thermal solution and artificial aging according to claim 3, characterized in that: In step (2), during the solution treatment process, the heating is carried out by furnace heating at a rate of 160-170℃ / s; and the cooling is carried out by water cooling.

5. The method for preparing 7108 aluminum alloy based on Joule thermal solution and artificial aging according to claim 1, characterized in that: In step (2), the ultra-fast high-temperature sintering technology (UHS) is carried out using a Joule heating device (ultra-fast high-temperature sintering furnace). Specifically, the artificially aged 7108 aluminum alloy in step (1) is wrapped with electrically conductive carbon materials (graphene foam, graphite sheets, carbon felt, carbon paper, etc.). Then, the carbon paper wrapped with aluminum alloy is placed in the center of the heater of the ultra-fast high-temperature sintering furnace to ensure uniform heating during the heating process. Then, the furnace door is closed, and argon gas is repeatedly introduced 3-5 times to ensure that there is no air in the furnace to prevent high-temperature oxidation of the furnace components.

6. The method for preparing 7108 aluminum alloy based on Joule thermal solution and artificial aging according to claim 1, characterized in that: In step (3), the artificial aging process is carried out at an aging temperature of 120-160℃ and a holding time of 8-12h.

7. The method for preparing 7108 aluminum alloy based on Joule thermal solution and artificial aging according to claim 6, characterized in that: In step (3), during the artificial aging process, the heating is carried out by furnace heating at a rate of 0.5-1.5℃ / min; and the cooling is carried out by water cooling.

8. A 7108 aluminum alloy prepared by any one of the methods described in claims 1-7, characterized in that: The microstructure of this aluminum alloy contains precipitated phases including GP zones and η phases.

9. The 7108 aluminum alloy according to claim 8, characterized in that: The tensile strength of 7108 aluminum alloy after artificial aging at room temperature is 360-400 MPa, the yield strength is 280-310 MPa, and the elongation is 11-14%.

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