A method for preparing high-strength eutectic aluminum alloy by multi-element micro-alloying and multi-field coupling deep purification extrusion casting

Abstract

The application relates to a method for preparing a high-strength eutectic aluminum alloy by extrusion casting, and relates to a method for preparing a high-strength eutectic aluminum alloy by extrusion casting. The application aims at solving the technical problems of low room-temperature strength, poor high-temperature stability and many casting pores of the eutectic aluminum alloy. In the application, zirconium, vanadium and erbium micro-alloying form more stable and coherent L12 strengthening phases, and the aluminum liquid is deeply purified by multi-field coupling to eliminate the influence of hydrogen embrittlement and pores on the alloy performance, so that the high-strength eutectic aluminum alloy is prepared. By optimizing the compositions of transition elements and rare earth Er elements, the high-strength heat-resistant eutectic aluminum alloy with the performance of the original cast ingot comparable to that of the T6 heat-treated eutectic aluminum alloy is prepared, and the tensile strength and elongation of the high-strength heat-resistant eutectic aluminum alloy are 300.5 MPa and 3.49%, respectively.

Description

Technical Field

[0001] This invention relates to a method for preparing high-strength eutectic aluminum alloys by extrusion casting. Background Technology

[0002] Aluminum alloys inherently possess low density, high strength, high elongation, corrosion resistance, and good casting properties. Currently, with the global emphasis on energy conservation and emission reduction, sustainable development has become a crucial aspect of social development. Cast eutectic Al-Si alloys are widely used in the machinery manufacturing field, such as in aerospace, automotive, and transportation. However, for these applications, eutectic Al-Si alloys still face several challenges: achieving the required high-temperature performance and stability is difficult, and the alloy preparation process contains numerous defects such as porosity and inclusions.

[0003] The coupling of the temperature field and the ultrasonic field, through reasonable temperature and ultrasonic frequency control, controls the hydrogen content in the melt while simultaneously removing hydrogen through the cavitation effect of the ultrasonic field. Summary of the Invention

[0004] The present invention aims to solve the technical problems of low room temperature strength, poor high temperature stability and numerous casting pores in current cast eutectic aluminum alloys, and provides a method for preparing high-strength eutectic aluminum alloys by multi-element microalloying and multi-field coupling deep purification extrusion casting.

[0005] The method for preparing high-strength eutectic aluminum alloys by multi-element microalloying and multi-field coupled deep purification extrusion casting of the present invention is carried out according to the following steps:

[0006] I. The composition of each element in the alloy by mass fraction is as follows: Si 12%–13%, Cu 4.5%–5.5%, Ni 1.9%–2.1%, Zr 0.18%–0.25%, V 0.2%–0.3%, Er 0.17%–0.2%, Ti 0.08%–0.12%, B 0.01%–0.02%, Sr 0.01%–0.02%, with the remainder being pure Al;

[0007] The raw materials are weighed according to the mass ratio of each element mentioned above. The raw materials are Al-Si master alloy, Al-Cu master alloy, Al-Ni master alloy, Al-V master alloy, Al-Zr master alloy, Al-Er master alloy, Al-Ti-B master alloy, Al-Sr master alloy and pure aluminum.

[0008] II. Hydrogen embrittlement has a crucial impact on the properties of aluminum alloys, so it is essential to dry the intermediate alloy and pure aluminum to remove moisture before smelting: Place all the raw materials weighed in step one into a drying oven and dry them at 200℃~250℃ for 1.5h to achieve the purpose of alloy drying.

[0009] 3. Heat the pit-type melting furnace to 190℃~200℃, place the graphite crucible in the pit-type melting furnace, and apply a zinc oxide aqueous solution with a mass fraction of 15%~20% to the inner wall of the graphite crucible. During this process, it is important to note that the temperature of the crucible should not exceed 200℃ when applying the zinc oxide solution. Otherwise, the zinc oxide solution will be difficult to form a coating on the surface of the crucible under the action of high-temperature steam, or the coating may not adhere tightly to the inner wall of the crucible and fall into the molten aluminum, causing inclusions.

[0010] 4. Heat the pit furnace to 450℃~460℃. During this process, the water vapor from the zinc oxide solution coating process can be removed, preventing the introduction of hydrogen from causing subsequent casting porosity. Place the dried pure aluminum from step 2 into a graphite crucible, and then continue to heat it to 720℃~730℃. After the pure aluminum melts, hold it at that temperature for 10min~12min.

[0011] 5. Raise the temperature of the pit furnace to 740℃~750℃, and put the Al-Si master alloy, Al-Cu master alloy, Al-Ni master alloy, Al-V master alloy, Al-Er master alloy and Al-Zr master alloy dried in step 2 into a graphite crucible. After all the master alloys have melted, hold the temperature for 10min~15min. To prevent the introduction of iron impurities, use a graphite rod to stir the molten aluminum liquid thoroughly for 5min~10min.

[0012] 6. Lower the temperature of the pit furnace to 720℃~730℃, add the modified Al-Sr master alloy dried in step 2 to the aluminum melt, and let it stand for 5min~10min after the modified agent has completely melted; add the refined Al-Ti-B master alloy dried in step 2 to the aluminum melt at 720℃~730℃, and hold for 10min~15min after the refined agent has completely melted. Then, in order to ensure that the modified agent, refined agent and other metal elements are fully mixed and to prevent unevenness, stir thoroughly for 10min~15min, and then let it stand for 10min~15min.

[0013] 7. Stabilize the furnace temperature of the pit furnace at 720±5℃. Place the titanium alloy tool head of the ultrasonic equipment into the molten aluminum alloy and preheat until both the titanium alloy tool head and the molten aluminum alloy reach 720±5℃. The introduction of the titanium alloy tool head effectively avoids the introduction of iron impurities. To ensure degassing efficiency, the distance between the top of the titanium alloy tool head and the surface of the molten aluminum alloy should be greater than or equal to 6cm, and the distance between the bottom of the titanium alloy tool head and the bottom of the crucible should be greater than or equal to 2cm. Then, insert a hollow graphite rod containing argon gas into the aluminum alloy... In the melt, the bottom of the hollow graphite rod is 5mm to 10mm deeper than the bottom of the titanium alloy tool head to ensure optimal coupling between the ultrasonic field and the argon field during degassing. The argon source and ultrasonic equipment are started. To ensure the uniformity of degassing, the hollow graphite rod is rotated back and forth alternately in clockwise and counterclockwise directions around the titanium alloy tool head during the introduction of argon gas. The degassing time is 110s to 130s, the flow rate of argon gas introduced during the coupled degassing process is 0.4L / min to 0.5L / min, and the ultrasonic frequency is 19.8kHz.

[0014] The top of the hollow graphite rod is connected to an argon gas source;

[0015] 8. After degassing, remove the hollow graphite rod and ultrasonic equipment, and remove slag (use a metal spoon coated with zinc oxide to skim off various floating slags on the surface of the melt): Then let the aluminum alloy melt stand at 720±5℃ for 25min~30min to ensure uniform temperature and allow the gas that has not escaped to continue to escape, preventing porosity from being generated during the casting process.

[0016] 9. Perform squeeze casting at a casting temperature of 720±5℃, a mold temperature of 200℃~250℃, a holding time of 30s~40s, and a specific pressure of 390MPa. After obtaining the ingot, immediately quench it in water at a temperature of 80~100℃ to obtain an aluminum alloy ingot.

[0017] The introduction of microalloying elements (zirconium, vanadium, and erbium) in this invention can improve the high-temperature stability of the alloy while forming Al3(Er, Zr) to enhance the alloy strength. Furthermore, Si, V, and other solute atoms form clusters that serve as heterogeneous nucleation cores for the strengthening phase, which is highly beneficial for increasing the density of the precipitated phase.

[0018] In this invention, zirconium, vanadium and erbium are microalloyed to form a more stable and coherent L12 strengthening phase. The aluminum melt is deeply purified by multi-field coupling (temperature field, ultrasonic field and argon field) to eliminate the influence of hydrogen embrittlement and porosity on the alloy properties, thereby achieving the purpose of preparing high-strength eutectic aluminum alloy.

[0019] This invention optimizes the composition of transition elements and rare earth Er elements to prepare a high-strength heat-resistant eutectic aluminum alloy whose original ingot performance is comparable to some T6 heat-treated eutectic aluminum alloys, with a tensile strength of 300.5 MPa and an elongation of 3.49%. Attached Figure Description

[0020] Figure 1 This is a process flow diagram of the method of the present invention;

[0021] Figure 2 The phase diagram of the vertical section of the aluminum alloy ingot prepared for Experiment 1;

[0022] Figure 3 Graphs showing the tensile mechanical properties of the aluminum alloy ingot prepared for Experiment 1;

[0023] Figure 4 Scanning micrograph of the aluminum alloy ingot prepared for Experiment 1. Detailed Implementation

[0024] Specific Implementation Method 1: This implementation method is a method for preparing high-strength eutectic aluminum alloys through multi-element micro-alloying and multi-field coupling deep purification extrusion casting, specifically carried out according to the following steps:

[0025] I. The composition of each element in the alloy by mass fraction is as follows: Si 12%–13%, Cu 4.5%–5.5%, Ni 1.9%–2.1%, Zr 0.18%–0.25%, V 0.2%–0.3%, Er 0.17%–0.2%, Ti 0.08%–0.12%, B 0.01%–0.02%, Sr 0.01%–0.02%, with the remainder being pure Al;

[0026] The raw materials are weighed according to the mass ratio of each element mentioned above. The raw materials are Al-Si master alloy, Al-Cu master alloy, Al-Ni master alloy, Al-V master alloy, Al-Zr master alloy, Al-Er master alloy, Al-Ti-B master alloy, Al-Sr master alloy and pure aluminum.

[0027] II. Hydrogen embrittlement has a crucial impact on the properties of aluminum alloys, so it is essential to dry the intermediate alloy and pure aluminum to remove moisture before smelting: Place all the raw materials weighed in step one into a drying oven and dry them at 200℃~250℃ for 1.5h to achieve the purpose of alloy drying.

[0028] 3. Heat the pit-type melting furnace to 190℃~200℃, place the graphite crucible in the pit-type melting furnace, and apply a zinc oxide aqueous solution with a mass fraction of 15%~20% to the inner wall of the graphite crucible. During this process, it is important to note that the temperature of the crucible should not exceed 200℃ when applying the zinc oxide solution. Otherwise, the zinc oxide solution will be difficult to form a coating on the surface of the crucible under the action of high-temperature steam, or the coating may not adhere tightly to the inner wall of the crucible and fall into the molten aluminum, causing inclusions.

[0029] 4. Heat the pit furnace to 450℃~460℃. During this process, the water vapor from the zinc oxide solution coating process can be removed, preventing the introduction of hydrogen from causing subsequent casting porosity. Place the dried pure aluminum from step 2 into a graphite crucible, and then continue to heat it to 720℃~730℃. After the pure aluminum melts, hold it at that temperature for 10min~12min.

[0030] 5. Raise the temperature of the pit furnace to 740℃~750℃, and put the Al-Si master alloy, Al-Cu master alloy, Al-Ni master alloy, Al-V master alloy, Al-Er master alloy and Al-Zr master alloy dried in step 2 into a graphite crucible. After all the master alloys have melted, hold the temperature for 10min~15min. To prevent the introduction of iron impurities, use a graphite rod to stir the molten aluminum liquid thoroughly for 5min~10min.

[0031] 6. Lower the temperature of the pit furnace to 720℃~730℃, add the modified Al-Sr master alloy dried in step 2 to the aluminum melt, and let it stand for 5min~10min after the modified agent has completely melted; add the refined Al-Ti-B master alloy dried in step 2 to the aluminum melt at 720℃~730℃, and hold for 10min~15min after the refined agent has completely melted. Then, in order to ensure that the modified agent, refined agent and other metal elements are fully mixed and to prevent unevenness, stir thoroughly for 10min~15min, and then let it stand for 10min~15min.

[0032] 7. Stabilize the furnace temperature of the pit furnace at 720±5℃. Place the titanium alloy tool head of the ultrasonic equipment into the molten aluminum alloy and preheat until both the titanium alloy tool head and the molten aluminum alloy reach 720±5℃. The introduction of the titanium alloy tool head effectively avoids the introduction of iron impurities. To ensure degassing efficiency, the distance between the top of the titanium alloy tool head and the surface of the molten aluminum alloy should be greater than or equal to 6cm, and the distance between the bottom of the titanium alloy tool head and the bottom of the crucible should be greater than or equal to 2cm. Then, insert a hollow graphite rod containing argon gas into the aluminum alloy... In the melt, the bottom of the hollow graphite rod is 5mm to 10mm deeper than the bottom of the titanium alloy tool head to ensure optimal coupling between the ultrasonic field and the argon field during degassing. The argon source and ultrasonic equipment are started. To ensure the uniformity of degassing, the hollow graphite rod is rotated back and forth alternately in clockwise and counterclockwise directions around the titanium alloy tool head during the introduction of argon gas. The degassing time is 110s to 130s, the flow rate of argon gas introduced during the coupled degassing process is 0.4L / min to 0.5L / min, and the ultrasonic frequency is 19.8kHz.

[0033] The top of the hollow graphite rod is connected to an argon gas source;

[0034] 8. After degassing, remove the hollow graphite rod and ultrasonic equipment, and remove slag (use a metal spoon coated with zinc oxide to skim off various floating slags on the surface of the melt): Then let the aluminum alloy melt stand at 720±5℃ for 25min~30min to ensure uniform temperature and allow the gas that has not escaped to continue to escape, preventing porosity from being generated during the casting process.

[0035] 9. Perform squeeze casting at a casting temperature of 720±5℃, a mold temperature of 200℃~250℃, a holding time of 30s~40s, and a specific pressure of 390MPa. After obtaining the ingot, immediately quench it in water at a temperature of 80~100℃ to obtain an aluminum alloy ingot.

[0036] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the composition of each element in the alloy by mass fraction in step one is as follows: Si is 12%, Cu is 4.5%, Ni is 2%, Zr is 0.2%, V is 0.2%, Er is 0.2%, Ti is 0.1%, B is 0.02%, Sr is 0.02%, and the remainder is pure Al. Everything else is the same as in Specific Implementation Method One.

[0037] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the Al-Si master alloy mentioned in step one is an Al-50Si master alloy. Everything else is the same as in Specific Implementation Method One or Two.

[0038] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the Al-Cu master alloy mentioned in step one is an Al-50Cu master alloy. Everything else is the same as in Specific Implementation Methods One to Three.

[0039] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method Four in that the Al-Ni master alloy mentioned in step one is an Al-10Ni master alloy. Everything else is the same as in Specific Implementation Method Four.

[0040] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method Five in that the Al-V master alloy mentioned in step one is an Al-5V master alloy. Everything else is the same as in Specific Implementation Method Five.

[0041] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method Six in that the Al-Zr master alloy mentioned in step one is an Al-10Zr master alloy. Everything else is the same as in Specific Implementation Method Six.

[0042] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method Seven in that the Al-Er master alloy mentioned in step one is an Al-10Er master alloy. Everything else is the same as in Specific Implementation Method Seven.

[0043] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method Eight in that the Al-Ti-B intermediate alloy mentioned in step one is Al-5Ti-B. Everything else is the same as in Specific Implementation Method Eight.

[0044] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Method Nine in that the Al-Sr master alloy mentioned in step one is Al-10Sr. Everything else is the same as in Specific Implementation Method Nine.

[0045] The invention was verified using the following experiments:

[0046] Experiment 1: This experiment demonstrates a method for preparing high-strength eutectic aluminum alloys using multi-element microalloying and multi-field coupled deep purification extrusion casting. The specific steps are as follows:

[0047] I. The composition of each element in the alloy by mass fraction is as follows: Si 12%, Cu 4.5%, Ni 2%, Zr 0.2%, V 0.2%, Er 0.2%, Ti 0.1%, B 0.02%, Sr 0.02%, and the remainder is pure Al;

[0048] The raw materials were weighed according to the mass ratio of each element mentioned above. The raw materials were 408g of Al-50Si master alloy, 153g of Al-50Cu master alloy, 340g of Al-10Ni master alloy, 68g of Al-5V master alloy, 34g of Al-10Zr master alloy, 34g of Al-10Er master alloy, 34g of Al-5Ti-B alloy, 3.4g of Al-10Sr master alloy, and 625.6g of pure aluminum (99.99wt.%).

[0049] II. Hydrogen embrittlement has a crucial impact on the properties of aluminum alloys, so it is essential to dry the intermediate alloy and pure aluminum to remove moisture before smelting: Place all the raw materials weighed in step one into a drying oven and dry them at 200℃ for 1.5 hours to achieve the purpose of alloy drying.

[0050] 3. Heat the pit-type melting furnace to 200℃, place the graphite crucible in the pit-type melting furnace, and apply a 15% zinc oxide aqueous solution to the inner wall of the graphite crucible. During this process, it is important to note that the temperature of the crucible should not exceed 200℃ when applying the zinc oxide solution. Otherwise, the zinc oxide solution will be difficult to form a coating on the surface of the crucible under the action of high-temperature steam, or the coating may not adhere tightly to the inner wall of the crucible and fall into the molten aluminum, causing inclusions.

[0051] Fourth, heat the pit furnace to 450℃. This process can remove the moisture from the zinc oxide solution coating process and prevent the introduction of hydrogen from causing subsequent casting porosity. Place the dried pure aluminum from step two into a graphite crucible and then continue to heat it to 720℃. After the pure aluminum melts, hold it at that temperature for 10 minutes.

[0052] 5. Raise the temperature of the pit furnace to 740℃, and put the Al-Si master alloy, Al-Cu master alloy, Al-Ni master alloy, Al-V master alloy, Al-Er master alloy and Al-Zr master alloy dried in step 2 into a graphite crucible. After all the master alloys have melted, hold the temperature for 10 minutes. To prevent the introduction of iron impurities, use a graphite rod to stir the molten aluminum liquid thoroughly for 10 minutes.

[0053] 6. Lower the temperature of the pit furnace to 720℃, add the modified Al-Sr master alloy dried in step 2 to the aluminum melt, and let it stand for 5 minutes after the modified agent has completely melted; add the refined Al-Ti-B master alloy dried in step 2 to the aluminum melt at 720℃, and keep it at the temperature for 10 minutes after the refined agent has completely melted. Then, in order to ensure that the modified agent, refined agent and other metal elements are fully mixed and to prevent unevenness, stir thoroughly for 10 minutes, and then let it stand for 10 minutes.

[0054] 7. Stabilize the pit furnace temperature at 725℃. Place the titanium alloy tool head of the ultrasonic equipment into the molten aluminum alloy and preheat until both the tool head and the molten aluminum alloy reach 725℃. The introduction of the titanium alloy tool head effectively avoids the introduction of iron impurities. To ensure degassing efficiency, the distance between the top of the titanium alloy tool head and the molten aluminum alloy surface is 7cm, and the distance between the bottom of the tool head and the bottom of the crucible is 3cm. Then, insert a hollow graphite rod containing argon gas into the aluminum alloy... In the melt, the bottom of the hollow graphite rod is 5mm deeper than the bottom of the titanium alloy tool head to ensure optimal coupling between the ultrasonic and argon fields during degassing. The argon source and ultrasonic equipment are then activated. To ensure uniform degassing, the hollow graphite rod is rotated alternately clockwise and counterclockwise around the titanium alloy tool head during argon introduction, with a degassing time of 120 seconds. The argon flow rate during coupled degassing is 0.4 L / min, and the ultrasonic frequency is 19.8 kHz. A detailed equipment diagram is shown below. Figure 1 As shown;

[0055] The top of the hollow graphite rod is connected to an argon gas source;

[0056] 8. After degassing, remove the hollow graphite rod and ultrasonic equipment, and remove slag (use a metal spoon coated with zinc oxide to skim off various floating slags on the surface of the melt): Then the aluminum alloy melt is left to stand at 725℃ for 25 minutes to ensure uniform temperature and allow any gas that has not yet escaped to continue to escape, preventing porosity from being generated during the casting process.

[0057] 9. Perform squeeze casting at a casting temperature of 725℃, a mold temperature of 200℃, a holding time of 30s, and a specific pressure of 390MPa. After obtaining the ingot, immediately quench it in water at a temperature of 90℃ to obtain an aluminum alloy ingot.

[0058] The precipitates formed in the aluminum alloy ingot prepared in Experiment 1 were calculated using CALPHAD software. Figure 2 The phase diagram of the vertical section of the aluminum alloy ingot is as follows: Figure 2 As shown, the second phases that are currently widely considered to have good stability all appear in aluminum alloys, among which the main heat-resistant phases are L12-Al3M and D0. 22 -Al3M, D0 23 -Al3M and Al7Cu4Ni, where M is Zr, Ti, V, or Er. Furthermore, L12-Al3M exhibits good coherence with the aluminum alloy matrix, which is highly beneficial for improving mechanical properties. The addition of microalloying elements reduces the stacking fault energy of the aluminum alloy, resulting in a large number of stacking faults in both the matrix and eutectic silicon. The presence of stacking faults can hinder the formation of dislocations during the plastic deformation process of extrusion casting, further enhancing the alloy's properties.

[0059] The tensile mechanical properties of the aluminum alloy ingot prepared in Experiment 1 were tested using an Instron 5569. Figure 3 As shown, the alloy has a tensile strength of 300.5 MPa and a maximum elongation of 3.49%, which is a significant improvement over other eutectic aluminum alloys. Furthermore, the performance of the aluminum alloy ingot prepared in Experiment 1 has reached the mechanical properties of some T6 eutectic aluminum alloys.

[0060] Figure 4 The image shows the scanning microstructure of the aluminum alloy ingot prepared for Experiment 1. It can be seen from the image that the microstructure density is significantly improved after multi-field coupling degassing. No small pores or cracks were found at high magnification. Furthermore, the eutectic Si is mainly microstructured, without large blocky Si. The Al matrix is ​​mainly spherical or near-spherical, and the second phase is small in size and uniformly distributed. These features also contribute to the improvement of mechanical properties.

Claims

1. A method for preparing high-strength eutectic aluminum alloys by multi-element microalloying and multi-field coupling deep purification extrusion casting, characterized in that... The method for preparing high-strength eutectic aluminum alloys by multi-element microalloying and multi-field coupled deep purification extrusion casting is carried out according to the following steps: I. The composition of each element in the alloy by mass fraction is as follows: Si 12%–13%, Cu 4.5%–5.5%, Ni 1.9%–2.1%, Zr 0.18%–0.25%, V 0.2%–0.3%, Er 0.17%–0.2%, Ti 0.08%–0.12%, B 0.01%–0.02%, Sr 0.01%–0.02%, with the remainder being pure Al; The raw materials are weighed according to the mass ratio of each element mentioned above. The raw materials are Al-Si master alloy, Al-Cu master alloy, Al-Ni master alloy, Al-V master alloy, Al-Zr master alloy, Al-Er master alloy, Al-Ti-B master alloy, Al-Sr master alloy and pure aluminum.

2. Place all the weighed raw materials from step one into a drying oven and dry them at 200℃~250℃ for 1.5 hours to achieve the purpose of alloy drying; 3. Heat the pit-type melting furnace to 190℃~200℃, place the graphite crucible in the pit-type melting furnace, and apply a zinc oxide aqueous solution with a mass fraction of 15%~20% to the inner wall of the graphite crucible.

4. Heat the pit furnace to 450℃~460℃; put the dried pure aluminum from step 2 into the graphite crucible, and then continue to heat it to 720℃~730℃. After the pure aluminum melts, hold it at that temperature for 10min~12min.

5. Raise the temperature of the pit furnace to 740℃~750℃, and put the Al-Si master alloy, Al-Cu master alloy, Al-Ni master alloy, Al-V master alloy, Al-Er master alloy and Al-Zr master alloy dried in step 2 into a graphite crucible. After all the master alloys have melted, hold the temperature for 10min~15min, and use a graphite rod to stir the molten aluminum liquid thoroughly for 5min~10min.

6. Lower the temperature of the pit furnace to 720℃~730℃, add the modified Al-Sr master alloy dried in step 2 to the aluminum melt, and let it stand for 5min~10min after the modified agent has completely melted; add the refined Al-Ti-B master alloy dried in step 2 to the aluminum melt at 720℃~730℃, and hold for 10min~15min after the refined agent has completely melted, then stir thoroughly for 10min~15min, and then let it stand for 10min~15min.

7. Stabilize the furnace temperature of the pit furnace at 720±5℃. Place the titanium alloy tool head of the ultrasonic equipment into the aluminum alloy melt for preheating until both the titanium alloy tool head and the aluminum alloy melt reach 720±5℃. The distance between the top of the titanium alloy tool head and the surface of the melt should be greater than or equal to 6cm, and the distance between the bottom of the titanium alloy tool head and the bottom of the crucible should be greater than or equal to 2cm. Then, insert a hollow graphite rod containing argon gas into the aluminum alloy melt, with the bottom of the hollow graphite rod 5mm to 10mm deeper than the bottom of the titanium alloy tool head. Start the argon gas source and the ultrasonic equipment. During the argon gas introduction process, the hollow graphite rod rotates back and forth alternately in clockwise and counterclockwise directions around the titanium alloy tool head to stir. The degassing time is 110s to 130s, the flow rate of argon gas introduced during the coupling degassing process is 0.4L / min to 0.5L / min, and the ultrasonic frequency is 19.8kHz. The top of the hollow graphite rod is connected to an argon gas source; 8. After degassing, remove the hollow graphite rod and ultrasonic equipment, remove slag, and then let the aluminum alloy melt stand at 720±5℃ for 25min~30min.

9. Perform squeeze casting at a casting temperature of 720±5℃, a mold temperature of 200℃~250℃, a holding time of 30s~40s, and a specific pressure of 390MPa. After obtaining the ingot, immediately quench it in water at a temperature of 80~100℃ to obtain an aluminum alloy ingot.

2. The method for preparing high-strength eutectic aluminum alloys by multi-element microalloying and multi-field coupling deep purification extrusion casting according to claim 1, characterized in that... In step one, the composition of each element in the alloy by mass fraction is as follows: Si is 12%, Cu is 4.5%, Ni is 2%, Zr is 0.2%, V is 0.2%, Er is 0.2%, Ti is 0.1%, B is 0.02%, Sr is 0.02%, and the remainder is pure Al.

3. The method for preparing high-strength eutectic aluminum alloys by multi-element microalloying and multi-field coupling deep purification extrusion casting according to claim 1, characterized in that... The Al-Si master alloy mentioned in step one is an Al-50Si master alloy.

4. The method for preparing high-strength eutectic aluminum alloys by multi-element microalloying and multi-field coupling deep purification extrusion casting according to claim 1, characterized in that... The Al-Cu master alloy mentioned in step one is an Al-50Cu master alloy.

5. The method for preparing high-strength eutectic aluminum alloys by multi-element microalloying and multi-field coupling deep purification extrusion casting according to claim 1, characterized in that... The Al-Ni master alloy mentioned in step one is an Al-10Ni master alloy.

6. The method for preparing high-strength eutectic aluminum alloys by multi-element microalloying and multi-field coupling deep purification extrusion casting according to claim 1, characterized in that... The Al-V master alloy mentioned in step one is an Al-5V master alloy.

7. The method for preparing high-strength eutectic aluminum alloys by multi-element microalloying and multi-field coupling deep purification extrusion casting according to claim 1, characterized in that... The Al-Zr master alloy mentioned in step one is an Al-10Zr master alloy.

8. The method for preparing high-strength eutectic aluminum alloys by multi-element microalloying and multi-field coupling deep purification extrusion casting according to claim 1, characterized in that... The Al-Er master alloy mentioned in step one is an Al-10Er master alloy.

9. The method for preparing high-strength eutectic aluminum alloys by multi-element microalloying and multi-field coupling deep purification extrusion casting according to claim 1, characterized in that... The Al-Ti-B master alloy mentioned in step one is Al-5Ti-B.

10. The method for preparing high-strength eutectic aluminum alloys by multi-element microalloying and multi-field coupling deep purification extrusion casting according to claim 1, characterized in that... The Al-Sr master alloy mentioned in step one is Al-10Sr.

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