Preparation process of high-strength high-conductivity aluminum-lithium-copper alloy

Abstract

The application discloses a preparation process of high-strength and high-conductivity aluminum-lithium-copper alloy and belongs to the technical field of high-strength and high-conductivity aluminum alloy preparation.The high-strength and high-conductivity aluminum-lithium-copper alloy contains 1.6-2.2% of Li, 4.0-5.2% of Cu, 0.01-0.03% of Mg, 0.01-0.03% of Si, 0.02-0.04% of Zr and the balance of Al and inevitable impurity elements in percentage by mass.The finished material preparation method comprises ball-milling mixing, smelting and casting, pouring, homogenization treatment, electric pulse treatment, ultrasonic treatment, circulation treatment and medium-low temperature heat preservation treatment processes.The process increases the content of Cu, combines electric pulse and ultrasonic circulation treatment, obtains ideal atomic clusters and further improves the strength and conductive performance of the aluminum-lithium-copper alloy.The workpiece can be used in the fields of automobiles, electronics, aerospace and the like and has a very good industrial application prospect.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation process of high-strength and high-conductivity aluminum-lithium-copper alloy and belongs to the technical field of high-strength and high-conductivity aluminum alloy preparation. BACKGROUND

[0002] Aluminum-lithium alloy has the advantages of light weight, high strength and good processability and is suitable for fields such as aerospace and automobiles. However, the development of modern industry puts forward higher requirements for the strength and electrical conductivity of aluminum-lithium alloy.

[0003] At present, simply relying on improvement of the composition of elements or simply relying on adjustment of the production process to enhance the strength and electrical conductivity of aluminum-lithium-copper alloy material has gradually reached a bottleneck. However, the strength and electrical conductivity of aluminum-lithium-copper alloy can still be further improved from the synergistic effect of the two. The application has great help for improving the devices with high strength and electrical conductivity in the domestic market at present.

[0004] Invention patent CN117144213A introduces an aluminum-lithium alloy and a preparation method, the weight ratio of Cu and Mg is 1.38-2.92:1 by improving the alloy composition, and the tensile properties, fracture toughness and anisotropy of the alloy are improved. Invention patent CN117165880A introduces a process for improving the strength of an aluminum-lithium alloy containing a scandium element, a cast ingot of the aluminum-lithium alloy containing the scandium element is subjected to multi-pass hot rolling to obtain a hot-rolled plate, the hot-rolled plate is subjected to annealing treatment to obtain an annealed piece, the annealed piece is subjected to multi-pass cold rolling to obtain a cold-rolled plate, and finally the cold-rolled plate is subjected to solid solution treatment and aging treatment in sequence to obtain the aluminum-lithium alloy containing the scandium element. The initial cast ingot is directly subjected to plastic deformation, the morphology of the primary phase is significantly improved, the content of Cu atoms in the aluminum solid solution is increased, the microstructure is adjusted through the plastic deformation and heat treatment process, and the strength of the third-generation Al-Cu-Li alloy containing Sc is significantly improved.

[0005] The aluminum alloy material obtained by the above process forms different organizations by adding different element compositions and different element weight ratios, and improves the anisotropy and plasticity of the alloy, but the strength and electrical properties are not considered. Therefore, it is necessary to provide a processing technology for improving the strength and electrical conductivity of aluminum-lithium-copper alloy, and further expand the application of aluminum-lithium-copper alloy material in the fields of automobiles, electronics, aerospace, etc. SUMMARY

[0006] To solve the problems in the prior art, the application provides a preparation process of high-strength and high-conductivity aluminum-lithium-copper alloy, and the specific preparation steps are as follows:

[0007] (1) The aluminum-lithium copper alloy and copper powder are ball-milled and mixed in a ball mill, followed by smelting, refining, impurity removal, casting and homogenization processes to obtain an aluminum-lithium copper alloy sample.

[0008] (2) Place the aluminum alloy obtained in step (1) into an ultrasonic oscillator for ultrasonic treatment.

[0009] (3) The ultrasonically treated aluminum alloy is subjected to AC pulses for electrical pulse treatment.

[0010] (4) Ultrasonic treatment + electrical pulse treatment cycle treatment. Cyclic treatment can increase the required cluster ratio, thereby improving the mechanical properties of the alloy.

[0011] (5) After the last electrical pulse treatment, perform medium and low temperature heat preservation treatment.

[0012] Preferably, the aluminum-lithium-copper alloy in step (1) comprises the following components by mass percentage: 1.6-2.2% Li, 4.0-5.2% Cu, 0.01-0.03 Mg, 0.01-0.03 Si, 0.02-0.04% Zr, with the balance being Al and unavoidable impurities, and the total mass percentage of all components being 100%.

[0013] Preferably, in step (1), the ball milling media is steel balls with a diameter of 20 mm, and the ball milling time is 1 hour.

[0014] Preferably, in step (1), the melting process is carried out at a temperature of 560-630°C for 1 hour.

[0015] Preferably, in step (1), the mold needs to be preheated to 200°C before casting, the homogenization treatment temperature is 530°C, and the time is 2 hours.

[0016] Preferably, in step (2), the ultrasonic frequency of the ultrasonic treatment is 20kHz to 40kHz, the power density is 0.1 to 0.5W / cm2, the treatment time is 5 to 10min, and the treatment temperature is 30 to 70℃.

[0017] Preferably, in step (3), the pulse period of the electrical pulse processing is 50-80ms, the pulse width is 10-30μs, the pulse frequency is 1-10Hz, the pulse duty cycle is 30%, the temperature is 300-350℃, and the pulse time is not less than 30s.

[0018] Preferably, in step (4), the ultrasonic treatment + electrical pulse treatment cycle is no less than 3 times, and the interval between ultrasonic treatment and electrical pulse treatment is no more than 3 minutes, and the cooling medium is water.

[0019] Preferably, the low-temperature insulation treatment in step (5) is carried out at 100-150°C for 30 minutes.

[0020] The principle of this invention:

[0021] The strength and conductivity of aluminum-lithium-copper alloys are closely related to element content, processing technology, and the size, morphology, and quantity of precipitated phases. Increasing copper content introduces precipitates, such as copper-rich magnesium-copper (Al₂CuMg) phase, which enhances strength and conductivity. Silicon combines with magnesium to form Mg₂Si precipitates, improving strength and conductivity. Lithium combines with copper and aluminum to form T₁ (Al₂CuLi) precipitates, contributing to improved strength. Ultrasonic treatment induces molecular vibrations and transitions, generating stress that promotes dislocation slip, grain boundary movement, and grain refinement. It also reduces internal defects, inclusions, and porosity, increasing vacancy concentration and thus improving conductivity and strength. Electrical pulse treatment alters the surface microstructure, causing polarization and ionization, reducing crystal size, clarifying grain boundaries, forming a denser structure, removing impurities, and increasing vacancy density, making the alloy more prone to clustering. Ultrasonic and electrical pulse cyclic treatment results in a higher cluster ratio in the alloy, thereby improving its strength and conductivity. The synergistic effect of all these processes gives the aluminum-lithium-copper alloy material both high strength and high conductivity.

[0022] Beneficial effects of the present invention

[0023] (1) The present invention obtains an ideal high-strength and high-conductivity aluminum-lithium copper alloy by increasing the copper content and combining processes such as ball milling, melting and casting, casting, ultrasonic treatment, electric pulse treatment, cyclic treatment, and medium and low temperature heat preservation treatment.

[0024] (2) The addition of Cu obtains the desired precipitate microstructure, thereby improving the mechanical properties of the alloy.

[0025] (3) The specific ultrasonic + electrical pulse cycle treatment process ensures that the grain structure is improved, the grain refinement is high, the vacancy density is high, and the ideal cluster ratio is obtained, thereby improving the strength and conductivity of the alloy.

[0026] (4) This invention provides a new method for obtaining a high-strength, high-conductivity aluminum-lithium-copper alloy production process. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the production process of the high-strength, high-conductivity aluminum-lithium-copper alloy material of the present invention. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the content described.

[0029] Example 1

[0030] The preparation of a high-strength, high-conductivity aluminum-lithium-copper alloy, the raw materials and their contents used in this embodiment are shown in Table 1.

[0031] Table 1. Raw materials and their contents used in Example 1

[0032] Li Cu Mg Si Zr balance 2.2 5.2 0.03 0.03 0.04 Al and unavoidable impurities

[0033] The specific preparation steps are as follows:

[0034] (1) The aluminum-lithium-copper alloy and copper powder were mixed in a ball mill. The ball milling media steel balls with a diameter of 20 mm were used for the ball milling treatment for 1 hour. Then, the alloy was smelted at 630°C for 1 hour, followed by refining, impurity removal, and casting. Before casting, the mold was preheated to 200°C and the homogenization treatment was carried out at 530°C for 2 hours. The aluminum alloy sample with the composition of Table 1 above was obtained.

[0035] (2) The aluminum alloy obtained in step (1) is placed in an ultrasonic oscillator for ultrasonic treatment. The ultrasonic frequency is 40kHz and the power density is 0.5W / cm². 2 The processing time is 10 minutes and the processing temperature is 30℃.

[0036] (3) The ultrasonically treated aluminum alloy is subjected to an AC pulse for electrical pulse treatment. The pulse period is 70ms, the pulse width is 30μs, the pulse frequency is 5Hz, the pulse duty cycle is 30%, the temperature is 350℃, and the pulse time is 50s.

[0037] (4) Ultrasonic treatment + electrical pulse treatment cycle treatment, 6 cycles, 100s interval between each cycle, water as the cooling medium.

[0038] (5) After six cycles, the final electrical pulse treatment is carried out at a low temperature of 130°C to obtain a high-strength, high-conductivity aluminum-lithium-copper alloy.

[0039] The mechanical and electrical properties of the high-strength, high-conductivity aluminum-lithium-copper alloy obtained in this embodiment are shown in Table 2.

[0040] Table 2. Mechanical and electrical properties of aluminum-lithium-copper alloys according to specific embodiments of the present invention.

[0041] Yield strength / MPa Tensile strength / MPa Electrical conductivity % IAC 300 350 50

[0042] Example 2

[0043] The preparation of a high-strength, high-conductivity aluminum-lithium-copper alloy, the raw materials and their contents used in this embodiment are shown in Table 3.

[0044] Table 3. Raw materials and their contents used in Example 2

[0045] Li Cu Mg Si Zr balance 1.8 4.8 0.01 0.02 0.02 Al and unavoidable impurities

[0046] The specific preparation steps are as follows:

[0047] (1) The aluminum-lithium-copper alloy and copper powder were mixed in a ball mill. The ball milling media steel balls with a diameter of 20 mm were used for the ball milling treatment for 1 hour. Then, the alloy was smelted at 600°C for 1 hour, followed by refining, impurity removal, and casting. Before casting, the mold was preheated to 200°C, and the homogenization treatment was carried out at 530°C for 2 hours. The aluminum alloy sample with the composition of Table 3 above was obtained.

[0048] (2) The aluminum alloy obtained in step (1) is placed in an ultrasonic oscillator for ultrasonic treatment. The ultrasonic frequency is 30kHz and the power density is 0.5W / cm². 2 The processing time is 8 minutes and the processing temperature is 55℃.

[0049] (3) The ultrasonically treated aluminum alloy is subjected to an AC pulse for electrical pulse treatment. The pulse period is 75ms, the pulse width is 15μs, the pulse frequency is 10Hz, the pulse duty cycle is 30%, the temperature is 325℃, and the pulse time is 40s.

[0050] (4) Ultrasonic treatment + electrical pulse treatment cycle treatment, 4 cycles, 90s interval between each cycle, water as the cooling medium.

[0051] (5) After four cycles, the final electrical pulse treatment is followed by a low-temperature holding treatment at 150℃. The resulting high-strength, high-conductivity aluminum-lithium-copper alloy is obtained.

[0052] The mechanical and electrical properties of the high-strength, high-conductivity aluminum-lithium-copper alloy obtained in this embodiment are shown in Table 4.

[0053] Table 4. Mechanical and electrical properties of aluminum-lithium copper alloys according to specific embodiments of the present invention.

[0054] Yield strength / MPa Tensile strength / MPa Electrical conductivity % IAC 285 330 47

[0055] Example 3

[0056] The preparation of a high-strength, high-conductivity aluminum-lithium-copper alloy, the raw materials and their contents used in this embodiment are shown in Table 5.

[0057] Table 5. Raw materials and their contents used in Example 3

[0058] Li Cu Mg Si Zr balance 1.6 4.0 0.01 0.01 0.02 Al and unavoidable impurities

[0059] The specific preparation steps are as follows:

[0060] (1) The aluminum-lithium-copper alloy and copper powder were mixed in a ball mill. The ball milling media steel balls with a diameter of 20 mm were used for the ball milling treatment for 1 hour. Then, the alloy was smelted at a temperature of 560°C for 1 hour. The alloy was then refined, impurities were removed, and the alloy was cast. Before casting, the mold was preheated to 200°C and the homogenization treatment was carried out at a temperature of 530°C for 2 hours. The aluminum alloy sample with the composition of Table 5 above was obtained.

[0061] (2) The aluminum alloy obtained in step (1) is placed in an ultrasonic oscillator for ultrasonic treatment. The ultrasonic frequency is 20kHz and the power density is 0.1W / cm². 2 Processing time: 5 minutes; processing temperature: 70℃.

[0062] (3) The ultrasonically treated aluminum alloy is subjected to an AC pulse for electrical pulse treatment. The pulse period is 80ms, the pulse width is 10μs, the pulse frequency is 1Hz, the pulse duty cycle is 30%, the temperature is 300℃, and the pulse time is 30s.

[0063] (4) Ultrasonic treatment + electrical pulse treatment cycle treatment, 3 cycles, 180s interval between each cycle, water as the cooling medium.

[0064] (5) After three cycles, the final electrical pulse treatment is followed by a low-temperature heat treatment at 150℃. The resulting high-strength, high-conductivity aluminum-lithium-copper alloy is obtained.

[0065] The mechanical and electrical properties of the high-strength, high-conductivity aluminum-lithium-copper alloy obtained in this embodiment are shown in Table 6.

[0066] Table 6. Mechanical and electrical properties of aluminum-lithium copper alloys according to specific embodiments of the present invention.

[0067] Yield strength / MPa Tensile strength / MPa Electrical conductivity % IAC 273 305 40

[0068] Example 4

[0069] The preparation of a high-strength, high-conductivity aluminum-lithium-copper alloy, the raw materials and their contents used in this embodiment are shown in Table 7.

[0070] Table 7. Raw materials and their contents used in Example 4

[0071] Li Cu Mg Si Zr balance 2.0 4.5 0.02 0.02 0.03 Al and unavoidable impurities

[0072] The specific preparation steps are as follows:

[0073] (1) The aluminum-lithium-copper alloy and copper powder were mixed in a ball mill. The ball milling media steel balls with a diameter of 20 mm were used for the ball milling treatment for 1 hour. Then, the alloy was smelted at a temperature of 590°C for 1 hour. The alloy was then refined, impurities were removed, and the alloy was cast. Before casting, the mold was preheated to 200°C and the homogenization treatment was carried out at a temperature of 530°C for 2 hours. The aluminum alloy sample with the composition of Table 7 above was obtained.

[0074] (2) The aluminum alloy obtained in step (1) is placed in an ultrasonic oscillator for ultrasonic treatment. The ultrasonic frequency is 25 kHz and the power density is 0.3 W / cm². 2 The processing time is 7 minutes and the processing temperature is 55℃.

[0075] (3) The ultrasonically treated aluminum alloy is subjected to an AC pulse for electrical pulse treatment. The pulse period is 50ms, the pulse width is 15μs, the pulse frequency is 6Hz, the pulse duty cycle is 30%, the temperature is 330℃, and the pulse time is 55s.

[0076] (4) Ultrasonic treatment + electrical pulse treatment cycle treatment, 5 cycles, 180s interval between each cycle, water as the cooling medium.

[0077] (5) After five cycles, the final electrical pulse treatment is followed by a low-temperature holding treatment at 143℃. The resulting high-strength, high-conductivity aluminum-lithium-copper alloy is obtained.

[0078] The mechanical and electrical properties of the high-strength, high-conductivity aluminum-lithium-copper alloy obtained in this embodiment are shown in Table 8.

[0079] Table 8. Mechanical and electrical properties of aluminum-lithium-copper alloys according to specific embodiments of the present invention.

[0080] Yield strength / MPa Tensile strength / MPa Electrical conductivity % IAC 281 320 44

[0081] Comparative Example 1

[0082] The composition and preparation of the aluminum-lithium-copper alloy described in this embodiment are the same as those in Example 1, except that only one ultrasonic treatment and one electrical pulse treatment are performed. The specific preparation steps are as follows:

[0083] (1) The aluminum-lithium-copper alloy and copper powder were mixed in a ball mill. The ball milling media steel balls with a diameter of 20 mm were used for the ball milling treatment for 1 hour. Then, the alloy was smelted at 630°C for 1 hour, followed by refining, impurity removal, and casting. Before casting, the mold was preheated to 200°C and the homogenization treatment was carried out at 530°C for 2 hours. The aluminum alloy sample with the composition of Table 1 above was obtained.

[0084] (2) The aluminum alloy obtained in step (1) is placed in an ultrasonic oscillator for ultrasonic treatment. The ultrasonic frequency is 40kHz and the power density is 0.5W / cm².2 The processing time is 10 minutes and the processing temperature is 30℃.

[0085] (3) The ultrasonically treated aluminum alloy is subjected to an AC pulse for electrical pulse treatment. The pulse period is 70ms, the pulse width is 30μs, the pulse frequency is 5Hz, the pulse duty cycle is 30%, the temperature is 350℃, and the pulse time is 50s.

[0086] (4) Ultrasonic treatment + electrical pulse treatment, each single treatment, with an interval of 100s, and water as the cooling medium.

[0087] (5) After electrical pulse treatment, a medium-low temperature heat treatment at 130℃ is performed. The final high-strength, high-conductivity aluminum-lithium-copper alloy is obtained.

[0088] The mechanical and electrical properties of the final aluminum-lithium-copper alloy are shown in Table 9.

[0089] Table 9. Mechanical and electrical properties of aluminum-lithium-copper alloys according to specific embodiments of the present invention.

[0090] Yield strength / MPa Tensile strength / MPa Electrical conductivity % IAC 253 288 38

[0091] A comparison with Example 1 shows that ultrasonic + electrical pulse cyclic treatment, at least 3 times, can significantly improve the mechanical and electrical properties of the material. This is because, compared with the single cyclic treatment in the comparative example, the ultrasonic + electrical pulse cyclic treatment in Example 1, after 6 cycles, can significantly increase the concentration of vacancies. At the same time, the grains of the alloy are refined multiple times. During the cyclic process, the impurity content is sufficiently reduced, and the required cluster ratio is continuously increased, thereby improving the mechanical and electrical properties of the alloy.

[0092] Comparative Example 2

[0093] The composition and preparation of the aluminum-lithium-copper alloy described in this embodiment are the same as those in Example 2, except that the alloy after homogenization is directly subjected to electrical pulse treatment. The specific preparation steps are as follows:

[0094] (1) The aluminum-lithium-copper alloy and copper powder were mixed in a ball mill. The ball milling media steel balls with a diameter of 20 mm were used for the ball milling treatment for 1 hour. Then, the alloy was smelted at 600°C for 1 hour, followed by refining, impurity removal, and casting. Before casting, the mold was preheated to 200°C, and the homogenization treatment was carried out at 530°C for 2 hours. The aluminum alloy sample with the composition of Table 3 above was obtained.

[0095] (3) The aluminum alloy obtained in step (1) is subjected to an AC pulse for electrical pulse processing. The pulse period is 75ms, the pulse width is 15μs, the pulse frequency is 10Hz, the pulse duty cycle is 30%, the temperature is 325℃, and the pulse time is 40s.

[0096] (4) The alloy after electrical pulse treatment is subjected to a medium-low temperature holding treatment at 150℃. The final high-strength, high-conductivity aluminum-lithium-copper alloy is obtained.

[0097] The mechanical and electrical properties of the high-strength, high-conductivity aluminum-lithium-copper alloy obtained in this embodiment are shown in Table 10.

[0098] Table 10. Mechanical and electrical properties of aluminum-lithium-copper alloys according to specific embodiments of the present invention.

[0099] Yield strength / MPa Tensile strength / MPa Electrical conductivity % IAC 220 265 34

[0100] A comparison with Example 2 shows that the aluminum alloy obtained after homogenization treatment, which undergoes both ultrasonic and electrical pulse treatment, can significantly improve the mechanical and electrical properties of the material. This is because, compared with the comparative example which only underwent electrical pulse treatment, the grain structure of the alloy was changed after four cycles of ultrasonic + electrical pulse treatment in Example 2, resulting in smaller grain size. The smaller the grain size, the less electron scattering occurs at the grain boundaries, thereby increasing the mechanical and electrical properties of the alloy.

[0101] Comparative Example 3

[0102] The composition and preparation of the aluminum-lithium-copper alloy described in this embodiment are the same as those in Example 3, except that the alloy after homogenization is only subjected to ultrasonic treatment. The specific preparation steps are as follows:

[0103] (1) The aluminum-lithium-copper alloy and copper powder were mixed in a ball mill. The ball milling media steel balls with a diameter of 20 mm were used for the ball milling treatment for 1 hour. Then, the alloy was smelted at a temperature of 560°C for 1 hour. The alloy was then refined, impurities were removed, and the alloy was cast. Before casting, the mold was preheated to 200°C and the homogenization treatment was carried out at a temperature of 530°C for 2 hours. The aluminum alloy sample with the composition of Table 5 above was obtained.

[0104] (2) The aluminum alloy obtained in step (1) is placed in an ultrasonic oscillator for ultrasonic treatment. The ultrasonic frequency is 20kHz and the power density is 0.1W / cm². 2 The processing time was 5 minutes, and the processing temperature was 70℃. The final product was a high-strength, high-conductivity aluminum-lithium-copper alloy.

[0105] The mechanical and electrical properties of the high-strength, high-conductivity aluminum-lithium-copper alloy obtained in this embodiment are shown in Table 11.

[0106] Table 11 Results of mechanical and electrical properties of aluminum-lithium-copper alloys according to specific embodiments of the present invention

[0107] Yield strength / MPa Tensile strength / MPa Electrical conductivity % IAC 236 274 36

[0108] A comparison with Example 3 shows that ultrasonic + electrical pulse cyclic treatment can significantly improve the mechanical and electrical properties of the material. This is because, compared with the comparative example without electrical pulse treatment, Example 2 underwent ultrasonic + electrical pulse cyclic treatment three times. After ultrasonic treatment, the vacancy concentration of the alloy was initially increased. Then, electrical pulse treatment was performed to further increase the vacancy concentration and refine the grains, thereby increasing the proportion of the required atomic clusters. At the same time, the scattering of electrons at the grain boundaries was reduced, thus increasing the mechanical and electrical properties of the alloy.

[0109] Comparative Example 4

[0110] The composition and preparation of the aluminum-lithium-copper alloy described in this embodiment are the same as in Example 1, except that the alloy after homogenization is only subjected to medium-low temperature heat treatment. The specific preparation steps are as follows:

[0111] (1) The aluminum-lithium-copper alloy and copper powder were mixed in a ball mill. The ball milling media steel balls with a diameter of 20 mm were used for the ball milling treatment for 1 hour. Then, the alloy was smelted at 630°C for 1 hour, followed by refining, impurity removal, and casting. Before casting, the mold was preheated to 200°C and the homogenization treatment was carried out at 530°C for 2 hours. The aluminum alloy sample with the composition of Table 1 above was obtained.

[0112] (2) The aluminum alloy obtained in step (1) is subjected to a medium-low temperature heat treatment at 130℃. The final high-strength and high-conductivity aluminum-lithium-copper alloy is obtained.

[0113] The mechanical and electrical properties of the high-strength, high-conductivity aluminum-lithium-copper alloy obtained in this embodiment are shown in Table 12.

[0114] Table 12 Results of mechanical and electrical properties of aluminum-lithium copper alloys according to specific embodiments of the present invention

[0115] Yield strength / MPa Tensile strength / MPa Electrical conductivity % IAC 205 241 30

[0116] A comparison with Example 1 shows that ultrasonic + electrical pulse cyclic treatment significantly improves the mechanical and electrical properties of the material. This is because, compared to the comparative example without ultrasonic + electrical pulse cyclic treatment, Example 1 underwent six cycles of ultrasonic + electrical pulse cyclic treatment. Ultrasonic treatment can induce molecular vibration and transition, and generate stress that causes dislocation slip, grain boundary movement, and grain refinement in the alloy. It can also reduce internal defects, inclusions, and porosity in the alloy, and increase the number of vacancies to achieve a higher vacancy concentration. Electrical pulse treatment can change the microstructure of the alloy surface, causing polarization and ionization of the material surface, reducing the crystal size, clarifying grain boundaries, forming a denser structure, removing some impurities, and increasing the density of vacancies, making the alloy more prone to clustering. Ultrasonic + electrical pulse cyclic treatment results in a greater degree of grain refinement and a significant increase in vacancy density, thereby achieving a higher cluster ratio and increasing the mechanical and electrical properties of the alloy.

[0117] Comparative Example 5

[0118] The preparation and heat treatment process of the aluminum-lithium-copper alloy in this embodiment is the same as that in Example 4, except that the composition is shown in Table 13.

[0119] Table 13 Chemical composition of aluminum-lithium-copper alloy in specific embodiments of the present invention

[0120] Li Cu Mg Si Zr balance 2.0 2.0 0.02 0.02 0.03 Al and unavoidable impurities

[0121] The mechanical and electrical properties of the final aluminum-lithium-copper alloy are shown in Table 14.

[0122] Table 14. Mechanical and electrical properties of aluminum-lithium-copper alloys according to specific embodiments of the present invention.

[0123] Yield strength / MPa Tensile strength / MPa Electrical conductivity % IAC 247 279 31

[0124] A comparison with Example 4 shows that the mechanical and electrical properties of the aluminum alloy sample with reduced Cu content are lower than those of the alloy in Example 4 with a specific content. This is because the increase in copper content results in the formation of a copper-rich magnesium copper (Al2CuMg) phase in the alloy. Lithium forms a Ti (Al2CuLi) precipitate with copper and aluminum, which has a pinning effect on grain boundaries, thus inhibiting grain boundary migration and improving the mechanical and electrical properties of the aluminum-lithium-copper alloy.

[0125] In summary, the ball milling, melting and casting, casting, homogenization treatment, electrical pulse treatment, ultrasonic treatment, cyclic treatment, low-temperature and medium-low temperature holding treatment, and Cu content control methods described in this invention can effectively improve the structure of aluminum-lithium-copper alloys, continuously refine the grains, and reduce electron scattering at grain boundaries. This also reduces internal defects, inclusions, and porosity, resulting in a higher vacancy density and increasing the required cluster ratio. Through the synergistic effect of grain refinement, dislocation strengthening, and clustering, the mechanical and electrical properties of the aluminum-lithium-copper alloy are improved. This method is suitable for industrial applications and provides a feasible technical solution for the preparation of aluminum-lithium-copper alloy materials for automotive, electronics, and aerospace applications.

[0126] Finally, it should be noted that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0127] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style of the specification is merely for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A preparation process for a high-strength, high-conductivity aluminum-lithium-copper alloy, characterized in that, By adding Cu and optimizing the alloy composition, combined with ultrasonic treatment and electrical pulse treatment processes, the optimal strength and conductivity of the aluminum-lithium-copper alloy are achieved. This process includes the following steps: (1) The aluminum-lithium copper alloy and copper powder are ball-milled and mixed in a ball mill, followed by smelting, refining, impurity removal, casting and homogenization processes to obtain an aluminum-lithium copper alloy sample. (2) Place the aluminum alloy obtained in step (1) into an ultrasonic oscillator for ultrasonic treatment; (3) The ultrasonically treated aluminum alloy is subjected to AC pulses for electrical pulse treatment; (4) Cyclic treatment of ultrasonic treatment + electrical pulse treatment; (5) After the final electrical pulse treatment, perform medium and low temperature heat preservation treatment; The aluminum-lithium-copper alloy sample described in step (1) comprises the following components by mass percentage: 1.6–2.2% Li, 4.0–5.2% Cu, 0.01–0.03% Mg, 0.01–0.03% Si, 0.02–0.04% Zr, with the balance being Al and unavoidable impurities, and the total mass percentage of all components being 100%.

2. The preparation process of the high-strength, high-conductivity aluminum-lithium-copper alloy according to claim 1, characterized in that: In step (1), the ball milling media used in the ball milling mixing process is steel balls with a diameter of 20 mm, and the ball milling time is 1 hour.

3. The preparation process of the high-strength, high-conductivity aluminum-lithium-copper alloy according to claim 1, characterized in that: The melting temperature in step (1) is 560~630℃ and the melting time is 1h.

4. The preparation process of the high-strength, high-conductivity aluminum-lithium-copper alloy as described in claim 1, characterized in that: In step (1), the mold needs to be preheated to 200°C before casting.

5. The preparation process of the high-strength, high-conductivity aluminum-lithium-copper alloy as described in claim 1, characterized in that: In step (2), the ultrasonic frequency of the ultrasonic treatment is 20kHz~40kHz, and the power density is 0.1~0.5W / cm². 2 The processing time is 5 to 10 minutes, and the processing temperature is 30 to 70℃.

6. The preparation process of the high-strength, high-conductivity aluminum-lithium-copper alloy as described in claim 1, characterized in that: In step (3), the pulse period of the electrical pulse processing is 50-80ms, the pulse width is 10-30 μs, the pulse frequency is 1-10Hz, the pulse duty cycle is 30%, the temperature is 300-350℃, and the pulse time is not less than 30s.

7. The preparation process of the high-strength, high-conductivity aluminum-lithium-copper alloy as described in claim 1, characterized in that: In step (4), the ultrasonic treatment + electrical pulse treatment cycle shall be no less than 3 times, and the interval between ultrasonic treatment and electrical pulse treatment shall not exceed 3 minutes. The cooling medium is water.

8. The method for preparing the high-strength, high-conductivity aluminum-lithium-copper alloy as described in claim 1, characterized in that: The insulation temperature of the low-temperature insulation treatment in step (5) is 100-150℃, and the insulation time is 30min.

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