Manufacturing method for ultrahigh-strength and ductility aluminum alloy plate

Abstract

The present invention relates to the technical field of powder metallurgy manufacturing of aluminum alloy. Provided is a manufacturing method for an ultrahigh-strength and ductility aluminum alloy plate. The manufacturing method for an ultrahigh-strength and ductility aluminum alloy plate comprises: performing low-speed ball milling mixing on a liquid additive and aluminum alloy powder, then performing high-speed ball milling, and then drying same to obtain aluminum alloy mixed powder; performing cold isostatic pressing on the aluminum alloy mixed powder to obtain a square plate-shaped green body; sintering and densifying the square plate-shaped green body to obtain an aluminum plate sintered blank; carrying out hot rolling treatment on the aluminum plate sintered blank to obtain a fully-dense large-size aluminum alloy plate; and carrying out heat treatment on the fully-dense large-size aluminum alloy plate to obtain an ultrahigh-strength and ductility aluminum alloy plate. Compared with other traditional methods, the method of the present invention can achieve synergistic improvement of the properties of the manufactured aluminum alloy plate, such as the room-temperature plasticity, strength, product of strength and elongation, and fatigue property, and involves a simple technological process, thus facilitating large-scale industrial production and popularization and use.

Description

A method for preparing ultra-high strength and toughness aluminum alloy plate Technical Field

[0001] The present invention relates to the technical field of preparing aluminum alloys by powder metallurgy, and in particular to a method for preparing an ultra-high strength and toughness aluminum alloy plate. Background Art

[0002] With the development of strategic emerging industries in my country, such as lightweight transportation, new energy vehicles, high-end equipment manufacturing, and energy conservation and environmental protection, the demand for heat-treated and strengthened high-end aluminum alloy plates continues to grow. Aluminum alloy plates are used extensively in aerospace structural materials due to their higher specific strength and superior processing properties compared to steel. However, in actual production and manufacturing, problems with the microstructure, residual stress, and other performance indicators of large-scale aluminum alloy plates are caused by factors such as composition uniformity, control of the content of main and impurity elements, rolling processes, and heat treatment regulation. This is particularly true for 2000 and 7000 series high-strength aluminum alloys. Ultimately, these factors significantly affect the material's load-bearing capacity and fatigue performance, thereby reducing the safety of equipment operation.

[0003] At present, a variety of methods for preparing high-performance aluminum alloy sheets have been developed both at home and abroad.

[0004] For example, Chinese patent CN113957303A discloses a low-density, high-strength and toughness aluminum alloy plate and a preparation method thereof. Although the aluminum alloy plate obtained by this method has excellent performance, its melting and casting process is relatively complicated, and high-cost aluminum-lithium intermediate alloys and rare earth elements such as Er, Sc, and Ce need to be added to the composition. In addition, the thickness of the prepared aluminum alloy plate is very low, and it is a thin plate, and the strength and toughness of the aluminum alloy plate are low.

[0005] Chinese patent CN104046863B discloses a method for producing ultra-high-strength and tough aluminum alloy sheet with a large width-to-thickness ratio, resulting in a high-strength 7000 series aluminum alloy. However, the high alloying element content can easily lead to uneven composition distribution. The invention utilizes extrusion, which limits the sheet width. Furthermore, when the sheet is 20 mm thick, the elongation is significantly low, and the width of the extruded sheet is also relatively small.

[0006] Chinese patent CN115627396A discloses an ultra-high strength, toughness, corrosion-resistant, ultra-long aluminum alloy plate and its preparation method. It targets aluminum alloys with specific compositions. The plate preparation method adopted is not powder metallurgy. The microstructure distribution of the prepared plate is uneven, and multi-stage rolling and multi-stage aging are required. The cost is high, the process is long, and the tensile strength is low.

[0007] Chinese patent CN110172623A discloses a high-strength and toughness aluminum alloy and its preparation method, which requires improvements in both composition and preparation. The alloy has a large number of components and a high cost. The preparation method requires the alloy ingot to be homogenized before extrusion, and the width of the extruded plate is also relatively small. The plate prepared by the subsequent peak aging process has a low elongation and a long preparation process.

[0008] Therefore, there is an urgent need to develop low-cost, short-process manufacturing technology for high-performance aluminum alloy sheets. Summary of the Invention

[0009] The technical problem to be solved by the present invention is that most of the current aluminum alloy plate preparations are obtained by improving the alloy composition and smelting preparation, machining and heat treatment, but these have technical defects such as high alloy cost, long preparation process, and inability to synergistically improve strength and plasticity. In particular, the extrusion forming will limit the width of the plate and the degree of homogenization will be low, and the subsequent heat treatment will cause the grain to grow, the plasticity to increase, and the strength to decrease.

[0010] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0011] A method for preparing an ultra-high strength and toughness aluminum alloy plate comprises the following steps:

[0012] S1, mixing the liquid additive and the aluminum alloy powder by low-speed ball milling, then performing high-speed ball milling, and then drying to obtain an aluminum alloy mixed powder;

[0013] S2, cold isostatically pressing the aluminum alloy mixed powder of S1 to obtain a square plate-shaped green body;

[0014] S3, sintering and densifying the square plate-shaped green body of S2 to obtain an aluminum plate sintered body;

[0015] S4, hot rolling the aluminum plate sintered ingot obtained in S3 to obtain a fully dense large-sized aluminum alloy plate;

[0016] S5. The fully dense large-size aluminum alloy plate of S4 is heat-treated to obtain an ultra-high strength and toughness aluminum alloy plate.

[0017] Preferably, the aluminum alloy powder in S1 is 7075 aluminum alloy powder, 7055 aluminum alloy powder, 2324 aluminum alloy powder and other 2000 series and 7000 series high-strength aluminum alloy powders.

[0018] Preferably, the aluminum alloy powder in S1 is a gas atomized aluminum alloy powder with an average particle size of 5-50 μm.

[0019] Preferably, the liquid additive in S1 can generate a large amount of dispersed nano-reinforcement phases, such as Al2O3, Al4C3, and AlN, on the surface of the aluminum alloy powder during high-energy ball milling, which plays a role of dispersion strengthening, and then inhibits grain growth during hot rolling and heat treatment, thereby obtaining an ultra-high strength and toughness aluminum alloy plate.

[0020] Preferably, the liquid additive in S1 is composed of at least one of hydrogen peroxide, carbon tetrachloride or liquid ammonia, and other liquids that can generate a large amount of dispersed nano-reinforced phases on the surface of the aluminum alloy powder.

[0021] Preferably, the mass fraction of the liquid additive in S1 is 5-20 wt.%, and the rest is aluminum alloy powder.

[0022] Preferably, the liquid additive in S1 is a mixture of hydrogen peroxide and carbon tetrachloride, wherein the mass ratio of hydrogen peroxide to carbon tetrachloride is 1:1.

[0023] Preferably, the ball milling method in S1 is rolling ball milling, stirring ball milling, or planetary ball milling, and the ball milling is carried out under nitrogen or argon protection, with a ball-to-material ratio of 3:1-20:1; wherein: the speed of low-speed ball milling is 50-120 r / min, and the mixing time is 2-5 h; the speed of high-speed ball milling is 150-300 r / min, and the ball milling time is 10-60 h.

[0024] Preferably, the average particle size of the aluminum alloy mixed powder in S1 is 5-50 μm, and the thickness of the oxide film on the surface of the powder particles is 5-15 nm.

[0025] Preferably, the cold isostatic pressing sheath in S2 is a square silicone or rubber sheath, the cold isostatic pressing pressure is 100-300 MPa, the holding time is 30-300 s, the size of the sheath is 100 mm×10 mm×4 mm-4000 mm×2000 mm×200 mm, and the size of the square plate-shaped green body is 90 mm×9 mm×3.6 mm-3500 mm×1700 mm×180 mm.

[0026] Preferably, during the sintering densification in S3, the temperature is first kept at 200-350 °C for 0.5-3 h, then the temperature is increased to the sintering temperature at a heating rate of 5-10 °C / min, the sintering temperature is 450-630 °C, the holding time is 2-20 h, and then the furnace is cooled to room temperature. The density of the sintered aluminum plate is 90-99.5%.

[0027] Preferably, the hot rolling treatment temperature in S4 is 200-550°C, the single-pass reduction is 10-30%, and the total reduction is 40-95%, to obtain a fully dense large-size aluminum alloy sheet with a thickness of 0.5-50 mm.

[0028] Preferably, the heat treatment in S5 adopts T6 heat treatment process, the temperature of solution treatment is 450-550°C, the holding time is 1-5 hours, and water quenching is performed; the temperature of artificial aging is 120-180°C, the holding time is 12-48 hours, and air cooling is performed.

[0029] Preferably, the thickness of the S5 ultra-high strength and toughness aluminum alloy plate is 0.5-50 mm, the tensile strength is 530-740 MPa, the yield strength is 479-720 MPa, the yield strength ratio is 0.9-0.97, the elongation is 8-14%, and the strength-ductility product is 4.24-10.36 GPa%.

[0030] Preferably, if other conditions remain unchanged, and the particle size of the aluminum alloy powder increases from small to large, the properties of the finally prepared aluminum alloy plate, such as tensile strength, yield strength, elongation, room temperature impact energy, and fatigue life, gradually decrease.

[0031] Preferably, if other conditions remain unchanged and the amount of liquid additive added increases from a small amount to a large amount, the properties of the finally prepared aluminum alloy sheet, such as tensile strength, yield strength, elongation, room temperature impact energy, and fatigue life, gradually decrease.

[0032] Compared with the prior art, the above technical solution has at least the following beneficial effects:

[0033] The above scheme, the present invention proposes a method for preparing ultra-high strength and toughness aluminum alloy plates, which can solve the technical problems of long preparation process, uneven structure, high cost, low efficiency, low strength and toughness, and low fatigue performance of aluminum alloy plates in the existing technology, so that the strength and toughness of the aluminum alloy plates can be synergistically improved.

[0034] The present invention adds liquid additives so that nano-reinforced phases (Al2O3, Al4C3, AlN) are generated and adhered to the surface of aluminum alloy powder during high-energy ball milling. These nano-reinforced phases have excellent high-temperature stability and can inhibit dynamic recovery recrystallization during hot rolling, maintain fine grain structure, and improve hot working performance; during high-temperature plastic deformation, the nano-reinforced phases can also hinder dislocation movement and increase material strength; during high-temperature solid solution, the nano-reinforced phases hinder grain boundary migration and inhibit grain growth, ultimately obtaining ultra-high strength and toughness aluminum alloy plates.

[0035] The ultra-high strength and toughness aluminum alloy plate prepared by the present invention has a thickness of 0.5-50 mm, a tensile strength of 530-740 MPa, a yield strength of 479-720 MPa, a yield strength ratio of 0.9-0.97, an elongation of 8-14%, and a strength-ductility product of 4.24-10.36 GPa%.

[0036] The present invention further refines the microstructure, realizes the control of the uniformity of the microstructure of the rolled plate, has no anisotropy in the mechanical properties, and improves the yield rate and material utilization rate.

[0037] In summary, compared with other traditional methods, the method of the present invention can synergistically improve the room temperature plasticity, strength, strength-ductility product, fatigue performance and other properties of the prepared aluminum alloy plate through the addition of liquid additives and low-speed ball milling, high-energy ball milling, cold isostatic pressing, sintering densification, hot rolling treatment and heat treatment. The process flow is simple, which is conducive to large-scale industrial production and promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0039] FIG1 is a stress-strain curve of a 7075 aluminum alloy plate prepared by a method for preparing an ultra-high strength and toughness aluminum alloy plate according to Example 1 of the present invention;

[0040] FIG2 is a stress-strain curve of a 7055 aluminum alloy plate prepared by a method for preparing an ultra-high strength and toughness aluminum alloy plate according to Example 2 of the present invention.

[0041] FIG3 is a stress-strain curve diagram of a 2324 aluminum alloy plate prepared by a method for preparing an ultra-high strength and toughness aluminum alloy plate according to Example 3 of the present invention. Implementation Method

[0042] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1

[0043] A method for preparing an ultra-high strength and toughness 7075 aluminum alloy plate, the method comprising the following steps:

[0044] S1. A liquid additive having a mass ratio of H2O2 to CCl4 of 1:1 was mixed with 7075 aluminum alloy powder having an average particle size of 5 μm by low-speed ball milling. The mixture was placed in a stainless steel ball milling jar so that the mass fraction of the liquid additive was 5 wt%. Under argon protection, the low-speed ball milling was performed at a speed of 50 r / min for a mixing time of 2 h. The mixture was then subjected to high-speed ball milling at a speed of 150 r / min for a ball milling time of 60 h. The mixed aluminum alloy powder was then dried.

[0045] Among them: the ball milling method is stirred ball milling, and the ball-to-material ratio is 20:1;

[0046] During the high-energy ball milling process, the liquid additive can generate a large number of dispersed nano-strengthening phases, such as Al2O3 and Al4C3, on the surface of the aluminum alloy powder, which plays a role in dispersion strengthening. Subsequently, during the hot rolling and heat treatment process, the grain growth is inhibited, thereby obtaining ultra-high strength and toughness aluminum alloy plates.

[0047] The average particle size of the aluminum alloy mixed powder is 12 μm, and the thickness of the oxide film on the powder particle surface is 5 nm;

[0048] S2. Cold isostatic pressing the aluminum alloy mixed powder of S1 to obtain a square plate-shaped green body, wherein the cold isostatic pressing bag is a square silica gel bag with an inner wall size of 500 mm × 300 mm × 80 mm, the cold isostatic pressing pressure is 150 MPa, the holding time is 300 s, and the size of the square plate-shaped green body is 410 mm × 245 mm × 62 mm;

[0049] S3, sintering and densifying the square plate green body of S2 to obtain an aluminum plate sintered blank, wherein: first, the temperature is kept at 350 °C for 2 h, then the temperature is raised to 580 °C at a rate of 5 °C / min, and the temperature is kept for 2 h, and then the aluminum plate sintered blank is cooled to room temperature with the furnace. The density of the aluminum plate sintered blank is 98.2%;

[0050] S4, hot rolling the aluminum plate sintered in S3 to obtain a fully dense large-size aluminum alloy plate, wherein: the hot rolling temperature is 400°C, the single-pass reduction is 20%, and the total reduction is 70%, to obtain a fully dense large-size aluminum alloy plate with a thickness of 20 mm;

[0051] S5. The fully dense large-size aluminum alloy plate of S4 is heat treated to obtain an ultra-high strength and toughness aluminum alloy plate, wherein: the heat treatment adopts the T6 heat treatment process, the solid solution treatment temperature is 470°C, the holding time is 2 h, and water quenching is performed; the artificial aging temperature is 120°C, the holding time is 18 h, and air cooling is performed.

[0052] The ultra-high strength and toughness aluminum alloy plate prepared in this embodiment has a thickness of 20 mm, as shown in FIG1 , and has a tensile strength of 685 MPa, a yield strength of 663 MPa, a yield strength ratio of 0.968, an elongation of 11.6%, and a strength-ductility product of 7.946 GPa%.

[0053] In this embodiment, if other conditions remain unchanged and the particle size of the aluminum alloy powder increases from small to large, the properties of the finally prepared aluminum alloy plate, such as tensile strength, yield strength, elongation, room temperature impact energy, and fatigue life, gradually decrease.

[0054] In this embodiment, if other conditions remain unchanged and the amount of liquid additive added increases, the properties of the aluminum alloy plate finally prepared, such as tensile strength, yield strength, elongation, room temperature impact energy, and fatigue life, gradually decrease.

[0055] Example 2

[0056] A method for preparing an ultra-high strength and toughness 7055 aluminum alloy plate, the method comprising the following steps:

[0057] S1. A liquid ammonia additive and a 7055 aluminum alloy powder with an average particle size of 15 μm are mixed by low-speed ball milling. The mixture is placed in a stainless steel ball mill at a mass fraction of 20 wt% of the liquid additive. Under nitrogen protection, the low-speed ball milling is performed at a speed of 120 r / min for a mixing time of 5 h. The mixture is then subjected to high-speed ball milling at a speed of 300 r / min for 10 h. The mixed aluminum alloy powder is then dried.

[0058] Among them: the ball milling method is planetary ball milling, and the ball-to-material ratio is 10:1;

[0059] During the high-energy ball milling process, the liquid additive can generate a large amount of dispersed nano-strengthening phases, such as AlN, on the surface of the aluminum alloy powder, which plays a role in dispersion strengthening. Subsequently, during the hot rolling and heat treatment process, the grain growth is inhibited, thereby obtaining ultra-high strength and toughness aluminum alloy plates.

[0060] The average particle size of the aluminum alloy mixed powder is 20 μm, and the thickness of the oxide film on the powder particle surface is 15 nm;

[0061] S2. Cold isostatically pressing the aluminum alloy mixed powder of S1 to obtain a square plate-shaped green body, wherein the cold isostatically pressed jacket is a square rubber jacket with an inner wall size of 1300 mm × 600 mm × 120 mm, the cold isostatic pressing pressure is 300 MPa, the holding time is 30 s, and the size of the square plate-shaped green body is 1075 mm × 495 mm × 98 mm;

[0062] S3, sintering and densifying the square plate green body of S2 to obtain an aluminum plate sintered blank, wherein: first, the temperature is kept at 350 °C for 2 hours, then the temperature is raised to 450 °C at a rate of 5 °C / min, and the temperature is kept for 20 hours, and then the aluminum plate sintered blank is cooled to room temperature with the furnace. The density of the aluminum plate sintered blank is 90%;

[0063] S4, hot rolling the aluminum plate sintered in S3 to obtain a fully dense large-size aluminum alloy plate, wherein: the hot rolling temperature is 350°C, the single-pass reduction is 10%, and the total reduction is 60%, to obtain a fully dense large-size aluminum alloy plate with a thickness of 40 mm;

[0064] S5. The fully dense large-size aluminum alloy plate of S4 is heat treated to obtain an ultra-high strength and toughness aluminum alloy plate, wherein: the heat treatment adopts the T6 heat treatment process, the solid solution treatment temperature is 470°C, the holding time is 2 h, and water quenching is performed; the artificial aging temperature is 120°C, the holding time is 24 h, and air cooling is performed.

[0065] The ultra-high strength and toughness aluminum alloy plate prepared in this embodiment has a thickness of 40 mm, as shown in FIG2 , and has a tensile strength of 735 MPa, a yield strength of 708 MPa, a yield strength ratio of 0.963, an elongation of 8.4%, and a strength-ductility product of 6.174 GPa%.

[0066] In this embodiment, if other conditions remain unchanged and the particle size of the aluminum alloy powder increases from small to large, the properties of the finally prepared aluminum alloy plate, such as tensile strength, yield strength, elongation, room temperature impact energy, and fatigue life, gradually decrease.

[0067] In this embodiment, if other conditions remain unchanged and the amount of liquid additive added increases, the properties of the aluminum alloy plate finally prepared, such as tensile strength, yield strength, elongation, room temperature impact energy, and fatigue life, gradually decrease. Example 3

[0068] A method for preparing an ultra-high strength and toughness 2324 aluminum alloy plate, the method comprising the following steps:

[0069] S1. A liquid additive of H2O2 and 2324 aluminum alloy powder with an average particle size of 50 μm were mixed by low-speed ball milling. The mixture was placed in a stainless steel ball mill at a mass fraction of 10 wt% of the liquid additive. Under nitrogen protection, the low-speed ball milling was performed at a speed of 80 r / min for 3 h. The mixture was then subjected to high-speed ball milling at a speed of 200 r / min for 24 h. The mixed aluminum alloy powder was then dried.

[0070] Among them: the ball milling method is planetary ball milling, and the ball-to-material ratio is 15:1;

[0071] During the high-energy ball milling process, the liquid additive can generate a large amount of dispersed nano-strengthening phases, such as Al2O3, on the surface of the aluminum alloy powder, which plays a role in dispersion strengthening. Subsequently, during the hot rolling and heat treatment process, the grain growth is inhibited, thereby obtaining ultra-high strength and toughness aluminum alloy plates.

[0072] The average particle size of the aluminum alloy mixed powder is 50 μm, and the thickness of the oxide film on the powder particle surface is 8 nm;

[0073] S2. Cold isostatically pressing the aluminum alloy mixed powder of S1 to obtain a square plate-shaped green body, wherein the cold isostatically pressed jacket is a square rubber jacket with an inner wall size of 1800 mm × 600 mm × 150 mm, the cold isostatic pressing pressure is 200 MPa, the holding time is 120 s, and the size of the square plate-shaped green body is 1490 mm × 490 mm × 120 mm;

[0074] S3, sintering and densifying the square plate green body of S2 to obtain an aluminum plate sintered blank, wherein: first, the temperature is kept at 350 °C for 2 hours, then the temperature is raised to 630 °C at a rate of 5 °C / min, and the temperature is kept for 5 hours, and then the aluminum plate sintered blank is cooled to room temperature with the furnace. The density of the aluminum plate sintered blank is 99.5%;

[0075] S4, hot rolling the aluminum plate sintered in S3 to obtain a fully dense large-size aluminum alloy plate, wherein: the hot rolling temperature is 550°C, the single-pass reduction is 30%, and the total reduction is 89%, to obtain a fully dense large-size aluminum alloy plate with a thickness of 12.7 mm;

[0076] S5. The fully dense large-size aluminum alloy plate of S4 is heat treated to obtain an ultra-high strength and toughness aluminum alloy plate, wherein: the heat treatment adopts the T6 heat treatment process, the solid solution treatment temperature is 505°C, the holding time is 5 h, and water quenching is performed; the artificial aging temperature is 178°C, the holding time is 12 h, and air cooling is performed.

[0077] The thickness of the ultra-high strength and toughness aluminum alloy plate prepared in this embodiment is 12.7 mm, as shown in FIG3 , and has a tensile strength of 589 MPa, a yield strength of 562 MPa, a yield strength ratio of 0.954, an elongation of 13.7%, and a strength-ductility product of 8.069 GPa%.

[0078] In this embodiment, if other conditions remain unchanged and the particle size of the aluminum alloy powder increases from small to large, the properties of the finally prepared aluminum alloy plate, such as tensile strength, yield strength, elongation, room temperature impact energy, and fatigue life, gradually decrease.

[0079] In this embodiment, if other conditions remain unchanged and the amount of liquid additive added increases, the properties of the aluminum alloy plate finally prepared, such as tensile strength, yield strength, elongation, room temperature impact energy, and fatigue life, gradually decrease. Example 4

[0080] A method for preparing an ultra-high strength and toughness 2024 aluminum alloy plate, the method comprising the following steps:

[0081] S1. Mixing a liquid ammonia additive with an aluminum alloy powder having an average particle size of 10 μm by low-speed ball milling at a rotation speed of 50 r / min for 3 h; then performing high-speed ball milling at a rotation speed of 300 r / min for 10 h; and then drying to obtain an aluminum alloy mixed powder.

[0082] Among them: the ball milling method is planetary ball milling, and the ball-to-material ratio is 3:1;

[0083] During the high-energy ball milling process, the liquid additive can generate a large amount of dispersed nano-strengthening phases, such as AlN, on the surface of the aluminum alloy powder, which plays a role in dispersion strengthening. Subsequently, during the hot rolling and heat treatment process, the grain growth is inhibited, thereby obtaining ultra-high strength and toughness aluminum alloy plates.

[0084] The average particle size of the aluminum alloy mixed powder is 12 μm, and the thickness of the oxide film on the powder particle surface is 6 nm;

[0085] S2, cold isostatically pressing the aluminum alloy mixed powder of S1 to obtain a square plate-shaped green body, wherein the cold isostatic pressing jacket is a square rubber jacket, the cold isostatic pressing pressure is 180 MPa, the holding time is 100 s, the size of the jacket is 200 mm × 10 mm × 4 mm, and the size of the square plate-shaped green body is 190 mm × 8 mm × 3 mm;

[0086] S3, sintering and densifying the square plate-shaped green body of S2 to obtain an aluminum plate sintered blank, wherein: first, the green body is kept at 200 °C for 3 hours, then heated to the sintering temperature at a heating rate of 8 °C / min, the sintering temperature is 600 °C, the holding time is 2 hours, and then cooled to room temperature in the furnace. The density of the aluminum plate sintered blank is 98.9%;

[0087] S4, hot rolling the aluminum plate sintered in S3 to obtain a fully dense large-size aluminum alloy plate, wherein: the hot rolling temperature is 200°C, the single-pass reduction is 10%, and the total reduction is 40%, to obtain a fully dense large-size aluminum alloy plate with a thickness of 1.8 mm;

[0088] S5. The fully dense large-size aluminum alloy plate of S4 is heat treated to obtain an ultra-high strength and toughness aluminum alloy plate, wherein: the heat treatment adopts the T6 heat treatment process, the solid solution treatment temperature is 550°C, the holding time is 1 h, and water quenching is performed; the artificial aging temperature is 180°C, the holding time is 12 h, and air cooling is performed.

[0089] The ultra-high strength and toughness aluminum alloy plate prepared in this embodiment has a thickness of 1.8 mm, a tensile strength of 562 MPa, a yield strength of 509 MPa, a yield strength ratio of 0.905, an elongation of 10%, and a strength-ductility product of 5.62 GPa%.

[0090] In this embodiment, if other conditions remain unchanged and the particle size of the aluminum alloy powder increases from small to large, the properties of the finally prepared aluminum alloy plate, such as tensile strength, yield strength, elongation, room temperature impact energy, and fatigue life, gradually decrease.

[0091] In this embodiment, if other conditions remain unchanged and the amount of liquid additive added increases, the properties of the aluminum alloy plate finally prepared, such as tensile strength, yield strength, elongation, room temperature impact energy, and fatigue life, gradually decrease.

[0092] Example 5

[0093] A method for preparing an ultra-high strength and toughness 7050 aluminum alloy plate, the method comprising the following steps:

[0094] S1. Mixing a liquid additive of H2O2 with 7050 aluminum alloy powder having an average particle size of 20 μm by low-speed ball milling at a rotation speed of 80 r / min for 3 h; then performing high-speed ball milling at a rotation speed of 260 r / min for 40 h; and then drying to obtain an aluminum alloy mixed powder;

[0095] Among them: the ball milling method is rolling ball milling, and the ball-to-material ratio is 20:1;

[0096] During the high-energy ball milling process, the liquid additive can generate a large amount of dispersed nano-strengthening phases, such as Al2O3, on the surface of the aluminum alloy powder, which plays a role in dispersion strengthening. Subsequently, during the hot rolling and heat treatment process, the grain growth is inhibited, thereby obtaining ultra-high strength and toughness aluminum alloy plates.

[0097] The average particle size of the aluminum alloy mixed powder is 25 μm, and the thickness of the oxide film on the powder particle surface is 10 nm;

[0098] S2. Cold isostatically pressing the aluminum alloy mixed powder of S1 to obtain a square plate-shaped green body, wherein the cold isostatic pressing jacket is a square silica gel jacket, the cold isostatic pressing pressure is 190 MPa, the holding time is 200 s, the jacket dimensions are 1200 mm × 800 mm × 90 mm, and the square plate-shaped green body dimensions are 1100 mm × 710 mm × 78 mm;

[0099] S3, sintering and densifying the square plate-shaped green body of S2 to obtain an aluminum plate sintered blank, wherein: first, the green body is kept at 280 °C for 2 hours, then heated to the sintering temperature at a heating rate of 10 °C / min, the sintering temperature is 590 °C, the holding time is 12 hours, and then cooled to room temperature in the furnace. The density of the aluminum plate sintered blank is 99.1%;

[0100] S4, hot rolling the aluminum plate sintered in S3 to obtain a fully dense large-size aluminum alloy plate, wherein: the hot rolling temperature is 350°C, the single-pass reduction is 20%, and the total reduction is 50%, to obtain a fully dense large-size aluminum alloy plate with a thickness of 39 mm;

[0101] S5. The fully dense large-size aluminum alloy plate of S4 is heat treated to obtain an ultra-high strength and toughness aluminum alloy plate, wherein: the heat treatment adopts the T6 heat treatment process, the solid solution treatment temperature is 485°C, the holding time is 3 h, and water quenching is performed; the artificial aging temperature is 125°C, the holding time is 18 h, and air cooling is performed.

[0102] The ultra-high strength and toughness aluminum alloy plate prepared in this embodiment has a thickness of 39 mm, a tensile strength of 694 MPa, a yield strength of 669 MPa, a yield strength ratio of 0.964, an elongation of 10.5%, and a strength-ductility product of 7.287 GPa%.

[0103] In this embodiment, if other conditions remain unchanged and the particle size of the aluminum alloy powder increases from small to large, the properties of the finally prepared aluminum alloy plate, such as tensile strength, yield strength, elongation, room temperature impact energy, and fatigue life, gradually decrease.

[0104] In this embodiment, if other conditions remain unchanged and the amount of liquid additive added increases, the properties of the aluminum alloy plate finally prepared, such as tensile strength, yield strength, elongation, room temperature impact energy, and fatigue life, gradually decrease. Example 6

[0105] A method for preparing an ultra-high strength and toughness 2195 aluminum alloy plate, the method comprising the following steps:

[0106] S1. Mixing a liquid additive of CCl4 with 2195 aluminum alloy powder having an average particle size of 50 μm by low-speed ball milling at a rotation speed of 100 r / min for 2 h; then performing high-speed ball milling at a rotation speed of 150 r / min for 10 h; and then drying to obtain an aluminum alloy mixed powder;

[0107] Among them: the ball milling method is rolling ball milling, and the ball-to-material ratio is 10:1;

[0108] During the high-energy ball milling process, the liquid additive can generate a large number of dispersed nano-strengthening phases, such as Al4C3, on the surface of the aluminum alloy powder, which plays a role in dispersion strengthening. Subsequently, during the hot rolling and heat treatment process, the grain growth is inhibited, thereby obtaining ultra-high strength and toughness aluminum alloy plates.

[0109] The average particle size of the aluminum alloy mixed powder is 50 μm, and the thickness of the oxide film on the powder particle surface is 15 nm;

[0110] S2. Cold isostatically pressing the aluminum alloy mixed powder of S1 to obtain a square plate-shaped green body, wherein the cold isostatic pressing jacket is a square silica gel jacket, the cold isostatic pressing pressure is 300 MPa, the holding time is 30 s, the jacket dimensions are 1500 mm × 1000 mm × 50 mm, and the square plate-shaped green body dimensions are 1350 mm × 870 mm × 43 mm;

[0111] S3, sintering and densifying the square plate-shaped green body of S2 to obtain an aluminum plate sintered blank, wherein: first, the green body is kept at 300 °C for 2 hours, then heated to the sintering temperature at a heating rate of 5 °C / min, the sintering temperature is 550 °C, the holding time is 8 hours, and then cooled to room temperature in the furnace. The density of the aluminum plate sintered blank is 98.5%;

[0112] S4, hot rolling the aluminum plate sintered in S3 to obtain a fully dense large-size aluminum alloy plate, wherein the hot rolling temperature is 400°C, the single-pass reduction is 15%, and the total reduction is 95%, to obtain a fully dense large-size aluminum alloy plate with a thickness of 2.15 mm;

[0113] S5. The fully dense large-size aluminum alloy plate of S4 is heat treated to obtain an ultra-high strength and toughness aluminum alloy plate, wherein: the heat treatment adopts the T6 heat treatment process, the solid solution treatment temperature is 520°C, the holding time is 2 h, and water quenching is performed; the artificial aging temperature is 165°C, the holding time is 18 h, and air cooling is performed.

[0114] The ultra-high strength and toughness aluminum alloy plate prepared in this embodiment has a thickness of 2.15 mm, a tensile strength of 640 MPa, a yield strength of 618 MPa, a yield strength ratio of 0.966, an elongation of 9.3%, and a strength-ductility product of 5.952 GPa%.

[0115] In this embodiment, if other conditions remain unchanged and the particle size of the aluminum alloy powder increases from small to large, the properties of the finally prepared aluminum alloy plate, such as tensile strength, yield strength, elongation, room temperature impact energy, and fatigue life, gradually decrease.

[0116] In this embodiment, if other conditions remain unchanged and the amount of liquid additive added increases, the properties of the aluminum alloy plate finally prepared, such as tensile strength, yield strength, elongation, room temperature impact energy, and fatigue life, gradually decrease.

[0117] The above scheme, the present invention proposes a method for preparing ultra-high strength and toughness aluminum alloy plates, which can solve the technical problems of long preparation process, uneven structure, high cost, low efficiency, low strength and toughness, and low fatigue performance of aluminum alloy plates in the existing technology, so that the strength and toughness of the aluminum alloy plates can be synergistically improved.

[0118] The present invention adds liquid additives so that nano-reinforced phases (Al2O3, Al4C3, AlN) are generated and adhered to the surface of aluminum alloy powder during high-energy ball milling. These nano-reinforced phases have excellent high-temperature stability and can inhibit dynamic recovery recrystallization during hot rolling, maintain fine grain structure, and improve hot working performance; during high-temperature plastic deformation, the nano-reinforced phases can also hinder dislocation movement and increase material strength; during high-temperature solid solution, the nano-reinforced phases hinder grain boundary migration and inhibit grain growth, ultimately obtaining ultra-high strength and toughness aluminum alloy plates.

[0119] The ultra-high strength and toughness aluminum alloy plate prepared by the present invention has a thickness of 0.5-50 mm, a tensile strength of 530-740 MPa, a yield strength of 479-720 MPa, a yield strength ratio of 0.9-0.97, an elongation of 8-14%, and a strength-ductility product of 4.24-10.36 GPa%.

[0120] The present invention further refines the microstructure, realizes the control of the uniformity of the microstructure of the rolled plate, has no anisotropy in the mechanical properties, and improves the yield rate and material utilization rate.

[0121] In summary, compared with other traditional methods, the method of the present invention can synergistically improve the room temperature plasticity, strength, strength-ductility product, fatigue performance and other properties of the prepared aluminum alloy plate through the addition of liquid additives and low-speed ball milling, high-energy ball milling, cold isostatic pressing, sintering densification, hot rolling treatment and heat treatment. The process flow is simple, which is conducive to large-scale industrial production and promotion.

[0122] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing an ultra-high strength and toughness aluminum alloy plate, characterized in that: The preparation method of the ultra-high strength and toughness aluminum alloy plate comprises the following steps: S1, mixing the liquid additive and the aluminum alloy powder by low-speed ball milling, then high-speed ball milling, and then drying to obtain an aluminum alloy mixed powder; S2, cold isostatically pressing the aluminum alloy mixed powder of S1 to obtain a square plate-shaped green billet; S3, sintering and densifying the square plate-shaped green body of S2 to obtain an aluminum plate sintered green body; S4, hot rolling the aluminum plate sintered ingot of S3 to obtain a fully dense large-size aluminum alloy plate; S5. The fully dense large-size aluminum alloy plate of S4 is heat-treated to obtain an ultra-high strength and toughness aluminum alloy plate.

2. The method for preparing the ultra-high strength and toughness aluminum alloy sheet according to claim 1, characterized in that: The liquid additive in S1 is composed of at least one of hydrogen peroxide, carbon tetrachloride or liquid ammonia, and other liquids that can generate a large amount of dispersed nano-reinforced phases on the surface of the aluminum alloy powder.

3. The method for preparing the ultra-high strength and toughness aluminum alloy sheet according to claim 1, characterized in that: The mass fraction of liquid additive in S1 is 5-20 wt.%, and the rest is aluminum alloy powder.

4. The method for preparing the ultra-high strength and toughness aluminum alloy sheet according to claim 1, characterized in that: The ball milling methods in S1 include rolling ball milling, stirring ball milling, and planetary ball milling. The ball milling is carried out under the protection of nitrogen or argon, and the ball-to-material ratio is 3:1-20:1; among them: the rotation speed of low-speed ball milling mixing is 50-120 r / min, and the mixing time is 2-5 h; the rotation speed of high-speed ball milling is 150-300 r / min, and the ball milling time is 10-60 h.

5. The method for preparing the ultra-high strength and toughness aluminum alloy sheet according to claim 1, characterized in that: The average particle size of the aluminum alloy mixed powder in S1 is 5-50 μm, and the thickness of the oxide film on the surface of the powder particles is 5-15 nm.

6. The method for preparing the ultra-high strength and toughness aluminum alloy plate according to claim 1, characterized in that: The cold isostatic pressing package in S2 is a square silicone or rubber package, the cold isostatic pressing pressure is 100-300MPa, the holding time is 30-300s, the size of the package is 100 mm×10 mm×4 mm-4000 mm×2000 mm×200 mm, and the size of the square plate green body is 90 mm×9 mm×3.6 mm-3500 mm×1700 mm×180 mm.

7. The method for preparing the ultra-high strength and toughness aluminum alloy plate according to claim 1, characterized in that: During the sintering densification in S3, first keep the temperature at 200-350 °C for 0.5-3 h, then increase the temperature to the sintering temperature at a heating rate of 5-10 °C / min. The sintering temperature is 450-630 °C, and the holding time is 2-20 h. Then cool to room temperature with the furnace. The density of the sintered aluminum plate is 90-99.5%.

8. The method for preparing the ultra-high strength and toughness aluminum alloy plate according to claim 1, characterized in that: The hot rolling treatment temperature in S4 is 200-550 ℃, the single-pass reduction is 10-30%, and the total reduction is 40-95%, obtaining a fully dense large-size aluminum alloy plate with a thickness of 0.5-50 mm.

9. The method for preparing the ultra-high strength and toughness aluminum alloy plate according to claim 1, characterized in that: The heat treatment of S5 adopts T6 heat treatment process, the temperature of solution treatment is 450-550 ℃, the holding time is 1-5 h, and water quenching; the temperature of artificial aging is 120-180 ℃, the holding time is 12-48 h, and air cooling.

10. The method for preparing the ultra-high strength and toughness aluminum alloy plate according to claim 1, characterized in that: The thickness of S5 ultra-high strength and toughness aluminum alloy plate is 0.5-50 mm, the tensile strength is 530-740 MPa, the yield strength is 479-720 MPa, the yield strength ratio is 0.9-0.97, the elongation is 8-14%, and the strength-ductility product is 4.24-10.36 GPa%.

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