Homogeneous high-strength aluminum-lithium alloy as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of metal material metallurgy processing, and particularly discloses a homogeneous high-strength aluminum-lithium alloy and a preparation method and application thereof. According to the method for preparing the homogeneous high-strength aluminum-lithium alloy based on ultrasonic smelting and thermal mechanical treatment, the lithium-containing aluminum alloy serves as a raw material, high-purity argon is introduced to serve as protective gas while the lithium-containing aluminum alloy is smelted, the melt is cooled after being subjected to ultrasonic treatment to obtain a cast ingot, ultrasonic waves are used for mechanically stirring molten aluminum, and nonlinear effects such as cavitation and acoustic streaming are generated, so that the homogeneous high-strength aluminum-lithium alloy is prepared. The effects of ultrasonic-assisted molten aluminum degassing and impurity removal, segregation improvement, grain refinement and strengthening homogenization are achieved; a cast ingot is subjected to rolling deformation (a rolling technology combining hot rolling, deep cold rolling and warm rolling is adopted) and heat treatment after being subjected to homogenization treatment, the microscopic solidification structure of the aluminum-lithium alloy is refined, the segregation degree of solute elements is reduced, the phenomenon of coarse eutectic structure is improved, the yield strength and tensile strength of the aluminum-lithium alloy are improved, and the quality of an aluminum-lithium alloy blank plate is improved; the process is simple and the production cost is low.

Description

Technical Field

[0001] The present invention belongs to the technical field of metallurgical processing of metal materials, and specifically relates to a method for preparing a homogeneous high-strength aluminum-lithium alloy based on ultrasonic melting and thermomechanical treatment, as well as the aluminum-lithium alloy prepared by the method and its application. Background Art

[0002] Aluminum-lithium alloys are widely used in aerospace and other fields due to their excellent properties such as low density, high specific strength and specific stiffness. 2055 aluminum-lithium alloy belongs to the fourth generation of aluminum-lithium alloys and was registered by Alcoa in 2011. It can be used as a material for aircraft fuselage frames, beams and wing longitudinal beams, replacing traditional high-strength alloys such as 7055. 2055 aluminum-lithium alloy is almost the same as traditional alloys in key indicators such as tensile strength, anisotropy and fracture toughness, but its density is reduced by nearly 6%, which is of great significance in the aerospace field. However, in the manufacturing process of aluminum-lithium alloys, due to the addition of active metal solute elements, casting defects in conventional aluminum alloys are more likely to appear in aluminum-lithium alloy ingots, including loose pores, coarse grains, composition segregation, oxide inclusions, coarse metal compounds, excessive hydrogen content, etc., resulting in low strength of aluminum-lithium alloys.

[0003] In order to improve the strength of the alloy, Chinese patent application CN117535604A (Hebei University of Technology) discloses a method for strengthening lithium-containing (Li 0.5-2.5wt%) aluminum alloy, which includes solution treatment, sinusoidal waveform cyclic tension and compression treatment, and artificial aging. The specific operation steps are as follows: (1) heating the lithium-containing aluminum alloy (selected from grades 2020, 2090, 2050, 2055, etc.) to the supersaturated solid solution temperature single-phase region, keeping the temperature for 1-3 hours, and then quenching it with water or oil as a medium to room temperature; (2) placing the quenched aluminum alloy in a cyclic tension and compression treatment device at room temperature, using a sinusoidal waveform cyclic tension and compression treatment method, the duration of each sinusoidal waveform stretching and compression treatment is 1-5 seconds, the deformation of each cyclic stretching and compression is based on the size obtained in the previous time, and the strain amplitude of the stretching deformation is set to (2-6)×10 -3The frequency of the cyclic tension and compression treatment is set to 0.2-1 Hz, the tensile stress intensity and the compressive stress intensity rise rapidly before 100 cycles of tension and compression, the 100th tensile stress intensity and the compressive stress intensity are 1.15-2.12 times of the first tensile stress intensity and the compressive stress intensity, and rise slowly from the 100th to the 200th, the 200th tensile stress intensity and the compressive stress intensity are 1.01-1.15 times of the 100th tensile stress intensity and the compressive stress intensity, and rise more slowly after the 200th, so that the tensile stress intensity and the compressive stress intensity of each 100 times are 1-1.05 times of the tensile stress intensity and the compressive stress intensity of the first 100 times; the number of cyclic tension and compression treatments is 480-600 times; (3) the aluminum alloy after cyclic tension and compression treatment is placed in an aging furnace, heated to 140-185 ° C, the aging time is 5-48 hours, and then cooled to room temperature to obtain a strengthened aluminum alloy. Although this method can optimize the size and distribution of the precipitated phase of lithium-containing aluminum alloy and improve the yield strength and tensile strength of the aluminum alloy, its process is relatively complex, the production cycle is long, and the production cost is high.

[0004] Therefore, there is an urgent need to develop a homogeneous high-strength aluminum-lithium alloy with simple process and low cost and its preparation method. Summary of the Invention

[0005] The main technical problem solved by the present invention is to provide a homogeneous high-strength aluminum-lithium alloy and a preparation method thereof. By adjusting the process, the casting defects in the aluminum-lithium alloy (such as coarse grains, component segregation, etc.) are eliminated, the yield strength and tensile strength of the alloy are improved, and at the same time, the preparation process is simplified and the production cost is reduced.

[0006] Secondly, the present invention provides an application of a homogeneous high-strength aluminum-lithium alloy in the preparation of aerospace vehicles.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0008] A method for preparing a homogeneous high-strength aluminum-lithium alloy comprises the following steps:

[0009] (1) ultrasonically treating a lithium-aluminum alloy melt and casting the melt to obtain an alloy ingot;

[0010] (2) homogenizing the alloy ingot and then performing rolling and deformation processing to obtain an alloy billet;

[0011] The rolling deformation process adopts one or more rolling processes combining hot rolling, deep cold rolling and warm rolling;

[0012] (3) The alloy blank is heat treated to obtain a homogeneous high-strength aluminum-lithium alloy.

[0013] As a preferred embodiment of the present invention, in step (1), the mass percentage of Li in the lithium-containing aluminum alloy melt is 1.0-1.3 wt%.

[0014] As a preferred embodiment of the present invention, in step (1), the raw materials for preparing the lithium-containing aluminum alloy melt include but are not limited to one or more of the intermediate alloys Al10Li, Al50Cu, Al20Zn, Al10Ag, Al10Mn, Al10Ti, Al10Zr, pure Mg, and Al10Fe.

[0015] Specifically, the chemical composition of the lithium-containing aluminum alloy melt includes (in terms of mass percentage): Li 1.0-1.3wt%, Cu 3.2-4.2wt%, Zn 0.3-0.7wt%, Ag 0.2-0.7wt%, Mn 0.1-0.5wt%, Mg 0.2-0.6wt%, Ti0.08-0.12wt%, Zr 0.05-0.15wt%, Fe 0.08-0.12wt%, and the balance is Al.

[0016] As a preferred embodiment of the present invention, in step (1), the melting temperature of the lithium-containing aluminum alloy is 700-780°C, preferably 750°C.

[0017] Specifically, the smelting is carried out in a protective atmosphere, and the pressure of the protective gas (such as high-purity argon) is controlled to be 1-10 6 Pa, preferably 0.12 MPa.

[0018] As a preferred embodiment of the present invention, in step (1), the ultrasonic treatment has a power of 600-1400 W, a frequency of 2000±200 Hz, and a duration of 10-360 s, preferably a power of 800 W, a frequency of 2000 Hz, and a duration of 180 s.

[0019] Specifically, during the ultrasonic treatment, the bottom end of the ultrasonic radiation rod is immersed in the melt surface to a depth of 20-30 mm, preferably 20 mm.

[0020] Specifically, during the ultrasonic treatment, the temperature of the melt is controlled at 680-720°C, preferably 690°C.

[0021] As a preferred embodiment of the present invention, in step (2), the alloy ingot is subjected to a two-stage homogenization treatment, wherein the temperature of the primary treatment is controlled to be 420-490°C for 5-10 hours, and the temperature of the secondary treatment is controlled to be 500-550°C for 10-18 hours. Preferably, the temperature of the primary treatment is 460°C for 8 hours, and the temperature of the secondary treatment is 520°C for 12 hours.

[0022] As a preferred embodiment of the present invention, in step (2), the hot rolling process is as follows: the homogenized alloy ingot is subjected to hot rough rolling at 360-450°C for 2-4 passes, with a deformation of 8-12% per pass; thereafter, the alloy ingot is hot rolled at 360-450°C for 5-8 passes, with a deformation of 8-12% per pass, with a furnace holding time of 5-20 minutes between each pass, and the total rolling deformation is controlled to be 60%-90%, to obtain an alloy slab. Preferably, the alloy ingot is hot rough rolled at 420°C for 3 passes, with a deformation of 10% per pass; thereafter, the alloy ingot is hot rolled at 420°C for 5 passes, with a deformation of 10% per pass, with a furnace holding time of 10 minutes between each pass, and the total rolling deformation is controlled to be 80%. The deformation per pass is the deformation relative to the thickness of the alloy ingot. For example, if the alloy ingot is 10 mm thick and the reduction per pass is 1 mm, the corresponding deformation per pass is 10%.

[0023] As a preferred embodiment of the present invention, in step (2), the rolling process combining deep cold rolling and warm rolling is as follows: the homogenized alloy ingot is hot-rough rolled at 400-450°C for 2-4 times, with a deformation of 8-12% per pass; thereafter, solution treatment is performed and quenching is performed; the quenched plate is deep cold rolled at -180 to -200°C for 2-4 times, with a deformation of 8-12% per pass; thereafter, warm rolling is performed at 100-200°C for 1-3 times, with a deformation of 8-12% per pass, and each pass is returned to the furnace for insulation for 1-15 minutes, and the total rolling deformation is controlled to be 60%-90%, thereby obtaining an alloy billet. Preferably, the steel is rough rolled at 420°C for three passes, with a deformation of 10% per pass. Solution treatment and quenching are then performed. The quenched steel is then immersed in liquid nitrogen and cold rolled for three passes, with a deformation of 10% per pass. Warm rolling is then performed at 160°C for two passes, with a deformation of 10% per pass. The steel is then melted and held for 10 minutes between passes, with the total rolling deformation controlled to 80%. As above, the deformation per pass is relative to the thickness of the alloy ingot.

[0024] As a preferred embodiment of the present invention, in step (3), the heat treatment is reasonably selected according to different rolling processes. The alloy slab obtained by the hot rolling process is subjected to a solution-aging treatment, with the solution treatment temperature being controlled at 480-520°C for 0.5-1 hour, and the aging treatment temperature being controlled at 125-175°C for 12-36 hours. Preferably, the solution treatment is performed at 500°C for 1 hour, and the aging treatment is performed at 135°C for 24 hours.

[0025] Specifically, the alloy slab obtained by the rolling process combining deep cold rolling and warm rolling is subjected to aging treatment, and the aging treatment temperature is controlled to be 150-190° C. and the time is 0.5-2 hours, preferably 180° C. for 1 hour.

[0026] A homogeneous high-strength aluminum-lithium alloy prepared by the above method.

[0027] As a preferred embodiment of the present invention, the mass percentage of Li in the aluminum-lithium alloy is 1.0-1.3 wt%.

[0028] Specifically, the grade of the aluminum-lithium alloy is 2055, and its chemical composition includes (in terms of mass percentage): Li 1.0-1.3wt%, Cu 3.2-4.2wt%, Zn 0.3-0.7wt%, Ag 0.2-0.7wt%, Mn 0.1-0.5wt%, Mg0.2-0.6wt%, Ti 0.08-0.12wt%, Zr 0.05-0.15wt%, Fe 0.08-0.12wt%, and the balance is Al.

[0029] The invention discloses an application of a homogeneous high-strength aluminum-lithium alloy in the preparation of aerospace vehicles.

[0030] Beneficial effects of the present invention:

[0031] The method provided by the present invention for preparing a homogeneous high-strength aluminum-lithium alloy based on ultrasonic melting and thermomechanical treatment, realizes degassing and impurity removal, improves segregation, refines grains and strengthens homogenization during the casting process by setting ultrasonic assisted casting, and subsequently adopts a rolling process combining hot rolling, deep cold rolling and warm rolling, which can effectively refine the microscopic solidification structure of the aluminum-lithium alloy, reduce the degree of solute element segregation, improve the coarse eutectic structure, increase the yield strength and tensile strength, improve the quality of the aluminum-lithium alloy billet, and at the same time simplify the preparation process and reduce production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the operation of the ultrasonic melting device in Example 1.

[0033] Figure 2 This is a flow chart of the preparation process of the homogeneous high-strength aluminum-lithium alloy in Example 2.

[0034] Figure 3 This is a scanning electron micrograph of ultrasonically cast ingot #1 in Example 1.

[0035] To more clearly illustrate the technical solutions of the embodiments of the present invention, the above briefly introduces the drawings obtained in the experimental examples. It should be understood that the above drawings only illustrate certain experimental examples of the present invention and should not be construed as limiting the scope of protection of the claims. Those skilled in the art can also derive other relevant drawings based on these drawings without inventive effort. DETAILED DESCRIPTION

[0036] The technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments and experimental examples. However, it should be understood by those skilled in the art that the embodiments are only used to illustrate the technical solutions of the present invention and should not be regarded as limiting the scope of protection of the present invention. Based on the following embodiments, other technical solutions obtained by those skilled in the art without making any creative work, such as technical solutions obtained after modification, replacement or simple deformation, are all within the scope of protection of the present invention.

[0037] Unless otherwise specified, the experimental methods used in the following embodiments, comparative examples and experimental examples are conventional methods in the art; the equipment, instruments, raw materials, etc. used are all commonly used in the art unless otherwise specified; the terms, abbreviations, etc. involved have the conventional meanings in the art.

[0038] Example 1

[0039] This embodiment provides a homogeneous high-strength aluminum-lithium alloy and a preparation method thereof, comprising the following steps:

[0040] (1) Ultrasonic melting stage:

[0041] The raw materials of 2055 aluminum-lithium alloy (including the intermediate alloys Al10Li, Al50Cu, Al20Zn, Al10Ag, Al10Mn, Al10Ti, Al10Zr, pure Mg, and Al10Fe, with the alloy composition as shown in Table 1) were placed in a preheating furnace at 200°C for preheating and drying, and the hydrogen in the raw materials was removed as much as possible. At the same time, the ultrasonic rod and the high-purity graphite crucible were preheated; under the protection of 0.12MPa high-purity argon, the aluminum-lithium alloy was heated to 750°C by a resistance heating furnace device to completely melt it. After complete melting, the melt was cooled to 690°C and ultrasonic treatment was applied to the melt. The bottom end of the ultrasonic radiation rod was immersed in the melt liquid surface to a depth of 20mm, the ultrasonic power was 800W, the frequency was 2000Hz, and the ultrasonic time was 180s (the operation diagram of the ultrasonic melting device is shown in FIG). Figure 1 Then, under the same atmospheric pressure, the alloy melt was cast into a mold (a high-purity graphite crucible with a capacity of about 400 ml). After the casting was completed, the mold was air-cooled. When the ingot reached room temperature, it was demolded to obtain an ultrasonically melted ingot, which was recorded as ultrasonic ingot #1.

[0042] According to international standards, the yield strength of ultrasonic ingot #1 was measured to be 64.7MPa, the tensile strength was 120.2MPa, the elongation was 3.7%, and the average grain size was 244.8μm. Figure 3 shown.

[0043] Table 1 2055 aluminum-lithium alloy composition (wt%)

[0044]

[0045] (2) Deformation processing stage:

[0046] The ingot was subjected to a two-stage homogenization treatment, with the temperature of the first-stage treatment controlled at 460°C for 8 hours, and the temperature of the second-stage treatment controlled at 520°C for 12 hours; then the ingot after homogenization treatment was subjected to hot rolling deformation processing using a rolling mill, firstly, the furnace temperature was raised to the target rolling temperature of 420°C at a heating rate of 10°C / min, and after the temperature of the heating furnace stabilized, a 10mm thick sample was placed in the heating furnace and kept warm for 30 minutes, followed by 3 passes of hot rough rolling at 420°C with a reduction of 1mm for each pass, and after the hot rough rolling was completed, the hot rough rolled plate was continued to be hot rolled at 420°C for 5 passes with a reduction of 1mm for each pass, and returned to the furnace for insulation for 10 minutes between each pass, finally obtaining a 2mm thick thin plate with a total rolling deformation of 80%.

[0047] (3) Heat treatment stage:

[0048] After rolling, the aluminum-lithium alloy hot-rolled plate was subjected to solution-aging treatment to further enhance the mechanical properties of the aluminum-lithium alloy plate. First, the box-type resistance furnace was preheated to the solution temperature of 500°C and kept warm for 5 minutes. After the temperature stabilized, the hot-rolled sheet was placed in the plate and kept warm for 1 hour. After the solution was completed, water quenching was used for cooling. After the solution quenching, the hot-rolled plate was aged in an oil bath aging furnace with a temperature accuracy of ±0.1°C. The aging furnace was heated to the aging temperature of 135°C, kept warm for 24 hours after sample placement, and air-cooled to obtain a homogeneous high-strength 2055 aluminum-lithium alloy plate, which was recorded as ultrasonic hot-rolled plate #2.

[0049] According to international standards, the yield strength of ultrasonic hot-rolled plate #2 was measured to be 212.1 MPa, the tensile strength was 386.1 MPa, the elongation was 25.3%, and the average grain size was 28.5 μm.

[0050] Example 2

[0051] This embodiment provides a homogeneous high-strength aluminum-lithium alloy and a preparation method thereof, comprising the following steps:

[0052] (1) Ultrasonic melting stage:

[0053] The aluminum-lithium alloy raw material and ultrasonic melting operation are the same as in Example 1 to obtain an ultrasonic melting ingot.

[0054] (2) Deformation processing stage:

[0055] The ingot was subjected to a double-stage homogenization treatment, with the temperature of the first-stage treatment controlled at 460°C for 8 hours, and the temperature of the second-stage treatment controlled at 520°C for 12 hours; then the ingot after homogenization treatment was subjected to a rolling deformation process combining deep cold rolling and warm rolling using a rolling mill, firstly raising the furnace temperature to the target rolling temperature of 420°C at a heating rate of 10°C / min, and after the temperature of the heating furnace stabilized, placing a 10mm thick sample in the heating furnace for 30 minutes, and then performing 420°C hot rough rolling for 3 passes, with a reduction of 1mm per pass; after the hot rough rolling was completed, the hot rough rolled sample was solution treated at 500°C / 1h, and then water quenched; the 7mm thick sample after quenching was subjected to a multi-pass rolling process combining deep cold rolling and warm rolling, firstly the sample was deep cold rolled for 3 passes, with a reduction of 1mm per pass. The specific operation includes: immersing the sample in liquid nitrogen, keeping it warm at about -190℃ for 30 minutes, and then starting the first pass of deep cold rolling. Before each subsequent pass of deep cold rolling, the rolled sheet from the previous pass is immersed in liquid nitrogen for 10 minutes. After three passes of deep cold rolling deformation, the sample obtained by deep cold rolling is continued to be warm rolled, and the deep cold rolled sheet is placed in a 160℃ resistance furnace for 20 minutes of insulation treatment. The sheet is then quickly moved to the rolling mill for the first pass of warm rolling. Before the next pass of warm rolling begins, the rolled sheet from the previous pass is placed in a resistance furnace at 160℃ for 10 minutes (to ensure uniform heating inside and outside the sample). After two passes of warm rolling deformation, the reduction in each pass is 1mm, and finally a 2mm thick sheet is obtained with a total deformation of 80%.

[0056] (3) Heat treatment stage:

[0057] After rolling, the aluminum-lithium alloy rolled plate was aged in an oil bath aging furnace with a temperature accuracy of ±0.1°C. The aging furnace was heated to an aging temperature of 180°C, and the plate was kept warm for 1 hour after sample placement. The plate was then air-cooled to obtain a homogeneous high-strength aluminum-lithium alloy sheet, which was recorded as ultrasonic deep cold rolled + warm rolled plate #3.

[0058] According to international standards, the yield strength of ultrasonic deep cold rolled + warm rolled plate #3 was measured to be 489.9 MPa, the tensile strength was 533.6 MPa, the elongation was 7.9%, and the average grain size was 15.4 μm.

[0059] The preparation process flow chart of the homogeneous high-strength aluminum-lithium alloy in this embodiment is as follows: Figure 2 shown.

[0060] In other embodiments of the present invention, the composition of the 2055 aluminum-lithium alloy and the process parameters of ultrasonic melting, deformation processing (hot rolling, or a combination of deep cold rolling and warm rolling), and heat treatment can all take any value within a given range, which basically does not affect the performance of the aluminum-lithium alloy finally prepared.

[0061] Comparative Example 1

[0062] This comparative example provides an aluminum-lithium alloy and a preparation method thereof, which differs from Example 1 mainly in that: in step (1), no ultrasonic treatment is applied during alloy smelting to obtain an ordinary ingot #1; the operations of steps (2) and (3) are the same as those of Example 1 to obtain an ordinary cast plate #2.

[0063] Tests conducted according to international standards revealed that the yield strength of conventional ingot #1 was 48.8 MPa, the tensile strength was 82.8 MPa, the elongation was 2.2%, and the average grain size was 759.9 μm. Meanwhile, the yield strength of conventional cast plate #2 was 198.1 MPa, the tensile strength was 293.8 MPa, the elongation was 8.7%, and the average grain size was 42.8 μm.

[0064] Comparative Example 2

[0065] This comparative example provides an aluminum-lithium alloy and a preparation method thereof, which differs from Example 2 mainly in that: in step (1), no ultrasonic treatment is applied during alloy smelting, and the operations of steps (2) and (3) are the same as those of Example 2, to obtain an ordinary cast plate #3.

[0066] According to international standards, the yield strength of ordinary cast plate #3 was measured to be 345.9 MPa, the tensile strength was 375.3 MPa, the elongation was 4.2%, and the average grain size was 21.6 μm.

[0067] Table 2 Performance test results of aluminum-lithium alloys in Examples and Comparative Examples

[0068]

[0069] In summary, the method for preparing a homogeneous high-strength aluminum-lithium alloy based on ultrasonic melting and thermomechanical treatment provided by the present invention uses a lithium-containing aluminum alloy (such as 2055 aluminum-lithium alloy) as a raw material, and introduces high-purity argon as a protective gas while melting in a resistance furnace. The melt is ultrasonically treated and then cooled to obtain an ingot. Ultrasonic assistance is used to achieve degassing and impurity removal, improve segregation, refine grains, and enhance homogenization during the casting process; after the ingot is homogenized, it is rolled, deformed, and heat treated to refine the microscopic solidification structure of the alloy, reduce the degree of segregation of solute elements, and improve the coarse eutectic structure, thereby obtaining a homogeneous high-strength aluminum-lithium alloy. At the same time, the process is simple and the cost is low.

[0070] Although the technical solution of the present invention has been described in detail above using general descriptions, specific embodiments, and experimental examples, it should be noted that the embodiments and experimental examples are only intended to illustrate the technical solution and technical effects of the present invention and should not be construed as limiting the scope of protection of the present invention. Simple variations, modifications, or improvements based on the technical concept of the present invention are all within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a homogeneous high-strength aluminum-lithium alloy, characterized in that: The following steps are involved: (1) ultrasonically treating a lithium-aluminum alloy melt and casting the melt to obtain an alloy ingot; (2) homogenizing the alloy ingot and then performing rolling and deformation processing to obtain an alloy billet; The rolling deformation process adopts one or more rolling processes combining hot rolling, deep cold rolling and warm rolling; (3) The alloy blank is heat treated to obtain a homogeneous high-strength aluminum-lithium alloy.

2. The preparation method according to claim 1, wherein: In step (1), the mass percentage of Li in the lithium-containing aluminum alloy melt is 1.0-1.3 wt%; and / or, the melting temperature of the lithium-containing aluminum alloy is 700-780° C.; And / or, the ultrasonic treatment has a power of 600-1400 W, a frequency of 2000±200 Hz, and a time of 10-360 s; And / or, during the ultrasonic treatment, the bottom end of the ultrasonic radiation rod is immersed in the melt liquid surface to a depth of 20-30 mm; And / or, the temperature of the melt is controlled at 680-720° C. during the ultrasonic treatment.

3. The preparation method according to claim 2, wherein: In step (1), the chemical composition of the lithium-containing aluminum alloy melt includes: Li 1.0-1.3wt%, Cu 3.2-4.2wt%, Zn 0.3-0.7wt%, Ag 0.2-0.7wt%, Mn 0.1-0.5wt%, Mg 0.2-0.6wt%, Ti 0.08-0.12wt%, Zr 0.05-0.15wt%, Fe 0.08-0.12wt%, and the balance is Al; and / or, the melting temperature of the lithium-containing aluminum alloy is 750° C.; And / or, the ultrasonic treatment power is 800W, the frequency is 2000Hz, and the time is 180s; And / or, during the ultrasonic treatment, the bottom end of the ultrasonic radiation rod is immersed in the melt liquid surface to a depth of 20 mm; And / or, the temperature of the melt is controlled at 690° C. during the ultrasonic treatment.

4. The preparation method according to claim 1, wherein: In step (2), the alloy ingot is subjected to a two-stage homogenization treatment, wherein the temperature of the first treatment is controlled to be 420-490° C. for 5-10 hours, and the temperature of the second treatment is controlled to be 500-550° C. for 10-18 hours; And / or, the hot rolling process comprises: rough rolling the homogenized alloy ingot at 360-450° C. for 2-4 passes with a deformation of 8-12% per pass; then hot rolling the ingot at 360-450° C. for 5-8 passes with a deformation of 8-12% per pass, with reheating and holding for 5-20 minutes between passes, and controlling the total rolling deformation to 60%-90%, to obtain an alloy slab; And / or, the rolling process combining deep cold rolling and warm rolling is as follows: the homogenized alloy ingot is hot rough rolled at 400-450°C for 2-4 passes, with a deformation of 8-12% per pass; thereafter, solution treatment is performed and quenching is performed; the quenched plate is deep cold rolled at -180 to -200°C for 2-4 passes, with a deformation of 8-12% per pass; thereafter, warm rolling is performed at 100-200°C for 1-3 passes, with a deformation of 8-12% per pass, and each pass is melted down and kept warm for 1-15 minutes, and the total rolling deformation is controlled to 60%-90%, to obtain an alloy billet.

5. The preparation method according to claim 4, characterized in that: In step (2), the temperature of the primary treatment is controlled to be 460°C and the time is 8 hours, and the temperature of the secondary treatment is controlled to be 520°C and the time is 12 hours; And / or, the hot rolling process is: rough rolling the homogenized alloy ingot at 420° C. for 3 passes with a deformation of 10% per pass; then hot rolling at 420° C. for 5 passes with a deformation of 10% per pass, with a 10 minute return to the furnace between passes, and controlling the total rolling deformation to 80%; And / or, the rolling process combining deep cold rolling and warm rolling is as follows: the homogenized alloy ingot is subjected to hot rough rolling at 420°C for 3 passes, with a deformation of 10% per pass; thereafter, a solid solution treatment is performed and quenching is performed; the quenched plate is soaked in liquid nitrogen and then deep cold rolled for 3 passes, with a deformation of 10% per pass; thereafter, the plate is warm rolled at 160°C for 2 passes, with a deformation of 10% per pass, and each pass is melted down and kept warm for 10 minutes, so that the total rolling deformation is controlled to 80%.

6. The preparation method according to claim 1, wherein: In step (3), the heat treatment is: performing a solution-aging treatment on the alloy slab obtained by the hot rolling process, controlling the temperature of the solution treatment to be 480-520°C and the time to be 0.5-1h, and the temperature of the aging treatment to be 125-175°C and the time to be 12-36h; The alloy slab obtained by the rolling process combining deep cold rolling and warm rolling is subjected to aging treatment, and the aging treatment temperature is controlled to be 150-190° C. and the time is 0.5-2 hours.

7. The preparation method according to claim 6, characterized in that: In step (3), the heat treatment is: performing a solution-aging treatment on the alloy slab obtained by the hot rolling process, performing a solution treatment at 500°C for 1 hour and an aging treatment at 135°C for 24 hours; The alloy slab obtained by the rolling process combining deep cold rolling and warm rolling was subjected to aging treatment at 180° C. for 1 h.

8. A homogeneous high-strength aluminum-lithium alloy prepared by the method according to any one of claims 1 to 7.

9. The homogeneous high-strength aluminum-lithium alloy according to claim 8, characterized in that: The mass percentage of Li in the aluminum-lithium alloy is 1.0-1.3 wt%.

10. Use of the homogeneous high-strength aluminum-lithium alloy according to any one of claims 8 to 9 in the manufacture of aerospace vehicles.

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