High-toughness aluminum alloy and method for preparing high-toughness aluminum alloy through powder metallurgy method

Abstract

The invention discloses a high-strength and high-toughness aluminum alloy and a method for preparing the high-strength and high-toughness aluminum alloy through a powder metallurgy method, and relates to the field of preparation of aluminum alloy materials. The method comprises the following steps that aluminum alloy powder is prepared, and the aluminum alloy powder comprises, by mass, 1.0%-10.0% of Mg, 0.5%-2.0% of Si, 0.5%-5.0% of Cu and the balance Al; preparing an aluminum alloy powder blank; the temperature is increased to 100-300 DEG C, heat preservation is conducted for 0.5-1 hour, and then an aluminum alloy bar is extruded; and performing aging heat treatment. By optimizing the proportion of the alloy elements, the alloy elements can be fully dissolved in the aluminum-based melt as much as possible in the smelting process, the forming space of a strengthening phase is expanded through the components, meanwhile, the components are combined with precise control in the subsequent heat treatment process, and the aluminum alloy material with high strength, high plasticity and good machining performance is obtained.

Description

Technical Field

[0001] The present invention relates to the field of preparation of aluminum alloy materials, in particular to a high-strength and toughness aluminum alloy and a method for preparing the high-strength and toughness aluminum alloy by using a powder metallurgy method. Background Art

[0002] Aluminum alloys, due to their lightweight, high specific strength, excellent corrosion resistance, and processability, have broad applications in aerospace, transportation, electronics, and other fields. In the consumer electronics sector, high-strength materials are required for durability and excellent plasticity to accommodate complex processing techniques. Stringent requirements are also placed on surface properties (such as anodizing and polishing) and corrosion resistance. High-strength aluminum alloys based on the Al-Zn and Al-Cu families have poor ductility and suboptimal corrosion resistance, limiting their application in consumer products. 6-series aluminum alloys, with magnesium and silicon as their primary alloying elements, offer excellent machinability, formability, and corrosion resistance, while also possessing moderate strength. Traditional 6061 aluminum alloys consist of the following components by mass: Mg: 0.8%–1.2%; Si: 0.4%–0.8%; Cu: 0.15%–0.4%; Mn: 0.15%; Fe: 0.7%; Cr: 0.04%–0.35%; Zn: 0.25%; Ti: 0.15%; and Al: the balance. Due to the low content of dissolved elements in traditional 6061 aluminum alloys, the potential for improving mechanical properties is limited. Therefore, new methods are urgently needed to prepare new aluminum alloys with improved mechanical properties.

[0003] Currently, aluminum alloys are primarily strengthened and toughened through alloying processes. This is achieved by adjusting the ratio of primary alloying elements or adding other solid-solution elements, while microalloying can be achieved by adding other elements (such as rare earth elements). Chinese patent application number 202211310467.7 uses pure Al powder as the primary raw material, introducing elements such as Zr and Re as elemental powders or simple master alloy powders. After the raw powders are uniformly mixed in a specific proportion, aluminum alloy parts are produced through a process of pressing, sintering, and heat treatment. However, the aluminum alloy produced by this method suffers from unsatisfactory toughness, poor strength-toughness matching, and high cost of the added alloying elements. Chinese patent application number 201711098167.6 uses pure Al powder and powders of three alloying elements (Mg, Si, and Cu) or binary alloys in a specific proportion, followed by pressing, sintering, heat treatment, and subsequent surface treatment to produce aluminum alloy parts. This method simplifies the production process, improves efficiency, and reduces costs, but the alloy's strength improvement is less than ideal, and its plasticity is poor.

[0004] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a high-strength and toughness aluminum alloy and a method for preparing a high-strength and toughness aluminum alloy using powder metallurgy, aiming to improve the comprehensive properties of the aluminum alloy so that it has higher strength and toughness.

[0006] The technical solutions of the present invention are as follows: In a first aspect, the present invention provides a method for preparing a high-strength and toughness aluminum alloy by powder metallurgy, comprising the following steps: S1. Prepare aluminum alloy powder, wherein the aluminum alloy powder comprises the following components by mass fraction: Mg: 1.0% to 10.0%, Si: 0.5% to 2.0%, Cu: 0.5% to 5.0%, and Al: balance; S2, pressing the aluminum alloy powder into a shape to form an aluminum alloy powder blank; S3, heating the aluminum alloy powder body to 100-300° C. and keeping the temperature for 0.5-1 hour, and then extruding it into an aluminum alloy rod; S4. Performing aging heat treatment on the aluminum alloy bar.

[0007] Optionally, the aluminum alloy powder is prepared by gas atomization.

[0008] Optionally, the particle size of the aluminum alloy powder is less than 100 μm.

[0009] Optionally, the pressing pressure is 50-200 MPa.

[0010] Optionally, the temperature of the die and the aluminum alloy powder body used during extrusion are consistent.

[0011] Optionally, the extrusion ratio during extrusion is 10-50.

[0012] Optionally, the aging heat treatment is performed under an inert gas.

[0013] Optionally, the aging heat treatment is performed at a temperature of 100 to 300° C. for 10 to 20 hours.

[0014] In a second aspect, the present invention provides a high-strength and high-toughness aluminum alloy prepared by the method described above.

[0015] Beneficial effects: (1) The present invention optimizes the ratio of alloying elements such as Mg, Si, and Cu so that the alloying elements can be dissolved as fully as possible in the aluminum-based melt during the smelting process. This component design breaks through the limitation of the low element content in traditional 6061 aluminum alloy and expands the space for the formation of strengthening phases. The obtained aluminum alloy powder is then pressed and hot-extruded to obtain dense rods. At the same time, combined with the precise control of the subsequent aging heat treatment process, an aluminum alloy material with high strength, high plasticity, and good machinability is obtained. Through aging heat treatment, fine, dispersed strengthening phases are precipitated from the supersaturated solid solution. This method can significantly improve the comprehensive mechanical properties of aluminum alloys, especially in terms of strength and plasticity, and is suitable for engineering applications with high requirements for high strength and high toughness.

[0016] (2) The present invention further adopts a gas atomization method to prepare aluminum alloy powder. The aluminum alloy powder prepared by this method can solidify rapidly. A supersaturated solid solution is formed in the solidified powder, thereby effectively suppressing the precipitation of coarse second phases and significantly improving the solid solubility and distribution uniformity of alloying elements in the powder. A supersaturated solid solution is achieved from the powder making stage, that is, a large amount of solid solution of multiple alloying elements (such as Mg, Si, and Cu) is achieved in the aluminum alloy powder, suppressing the formation of coarse second phases, thereby obtaining a powder supersaturated solid solution with uniform composition distribution and higher strengthening potential.

[0017] (3) Controlling precipitation behavior through low-temperature aging heat treatment. After obtaining a dense material through hot extrusion, aging heat treatment in the range of 100-300°C is performed to slowly precipitate, refine, and disperse strengthening phases such as Mg, Si, Al, and Cu in the alloy, thereby significantly improving the strength of the material and achieving excellent strength-plasticity synergy. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a flowchart of the present invention.

[0019] Figure 2 Schematic diagram of the aging heat treatment of the present invention.

[0020] Figure 3 1 are metallographic images of conventional 6061 aluminum alloy powder and the aluminum alloy powders of Examples 1 to 6, wherein (a) is a metallographic image of conventional 6061 aluminum alloy powder; (b) is a metallographic image of the aluminum alloy powder of Example 1; (c) is a metallographic image of the aluminum alloy powder of Example 2; (d) is a metallographic image of the aluminum alloy powder of Example 3; (e) is a metallographic image of the aluminum alloy powder of Example 4; (f) is a metallographic image of the aluminum alloy powder of Example 5; and (g) is a metallographic image of the aluminum alloy powder of Example 6.

[0021] Figure 4The following are metallographic diagrams of aluminum alloy rods extruded using conventional 6061 aluminum alloy components and the components of Examples 1 to 6, wherein (a) is a metallographic diagram of the aluminum alloy rod made of 6061; (b) is a metallographic diagram of the aluminum alloy rod made of Example 1; (c) is a metallographic diagram of the aluminum alloy rod made of Example 2; (d) is a metallographic diagram of the aluminum alloy rod made of Example 3; (e) is a metallographic diagram of the aluminum alloy rod made of Example 4; (f) is a metallographic diagram of the aluminum alloy rod made of Example 5; and (g) is a metallographic diagram of the aluminum alloy rod made of Example 6.

[0022] Figure 5 The figures are metallographic images of the rods obtained by using the traditional 6061 aluminum alloy composition and the compositions of Examples 1 to 6 after aging heat treatment; wherein, (a) is the metallographic image of the aluminum alloy rod made of 6061 after aging heat treatment; (b) is the metallographic image of the aluminum alloy rod made in Example 1 after aging heat treatment; (c) is the metallographic image of the aluminum alloy rod made in Example 2 after aging heat treatment; (d) is the metallographic image of the aluminum alloy rod made in Example 3 after aging heat treatment; (e) is the metallographic image of the aluminum alloy rod made in Example 4 after aging heat treatment; (f) is the metallographic image of the aluminum alloy rod made in Example 5 after aging heat treatment; and (g) is the metallographic image of the aluminum alloy rod made in Example 6 after aging heat treatment.

[0023] Figure 6 The hardness comparison chart of each component in the extruded state and the aged state.

[0024] Figure 7 The figure is a comparison chart of the tensile properties of each component in the extruded state.

[0025] Figure 8 A comparison chart of the tensile properties of each component in the aged state. DETAILED DESCRIPTION

[0026] The present invention provides a high-strength and toughness aluminum alloy and a method for preparing the same using powder metallurgy. To clarify the objectives, technical solutions, and effects of the present invention, the present invention is described in further detail below. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention.

[0027] Traditional 6061 aluminum alloys have a low content of alloying elements. Those skilled in the art generally believe that a low content of alloying elements imparts excellent plasticity and toughness, ease of machining, and good weldability and corrosion resistance. Excessive levels of alloying elements can easily lead to elemental segregation, affecting material uniformity, and adding large amounts of alloying elements can also increase costs. However, the low content of dissolved elements in traditional 6061 aluminum alloys limits the potential for improving mechanical properties. Therefore, new methods are urgently needed to prepare new aluminum alloys with improved mechanical properties.

[0028] The embodiment of the present invention provides a method for preparing a high-strength and tough aluminum alloy by powder metallurgy, such as Figure 1 As shown, the following steps are included: S1. Prepare aluminum alloy powder, wherein the aluminum alloy powder comprises the following components by mass fraction: Mg: 1.0% to 10.0%, Si: 0.5% to 2.0%, Cu: 0.5% to 5.0%, and Al: balance; S2, pressing the aluminum alloy powder into a shape to form an aluminum alloy powder blank; S3, heating the aluminum alloy powder body to 100-300° C. and keeping the temperature for 0.5-1 hour, and then extruding it into an aluminum alloy rod; S4. Performing aging heat treatment on the aluminum alloy bar.

[0029] This embodiment optimizes the ratio of alloying elements such as Mg, Si and Cu so that the alloying elements can be dissolved as fully as possible in the aluminum-based melt during the smelting process. This component design breaks through the limitation of the low element content in the traditional 6061 aluminum alloy and expands the space for the formation of the strengthening phase. The obtained aluminum alloy powder is then pressed and formed, and then hot extruded to obtain a dense aluminum alloy bar. At the same time, it is combined with the precise control of the subsequent aging heat treatment process to obtain an aluminum alloy material with high strength, high plasticity and good machinability. Through aging heat treatment, fine, dispersed strengthening phases are precipitated in the supersaturated solid solution. This method can significantly improve the comprehensive mechanical properties of aluminum alloys, especially in terms of strength and plasticity, and is suitable for engineering application scenarios with high requirements for high strength and high toughness.

[0030] In one embodiment, the aluminum alloy powder is prepared by gas atomization.

[0031] It should be noted that the preparation method of aluminum alloy powder by gas atomization can be summarized as follows: the alloy raw materials are completely melted and uniformly mixed to form an aluminum alloy melt. The smelted aluminum alloy melt is introduced into an atomization chamber, where a high-speed airflow breaks up the liquid metal stream into small droplets, which are then rapidly cooled and solidified to obtain aluminum alloy powder.

[0032] The aluminum alloy powder prepared using this method solidifies rapidly. A supersaturated solid solution forms in the solidified powder, effectively suppressing the precipitation of coarse second phases and significantly improving the solubility and uniformity of alloying elements in the powder. Achieving a supersaturated solid solution from the powder preparation stage involves extensive solid dissolution of multiple alloying elements (such as Mg, Si, and Cu) within the aluminum alloy powder, suppressing the formation of coarse second phases. This results in a supersaturated solid solution with uniform composition distribution and enhanced strengthening potential.

[0033] In one embodiment, the aluminum alloy powder has a particle size of less than 100 μm, specifically, an aluminum alloy powder with a particle size of 0 to 50 μm, or an aluminum alloy powder with a particle size of 50 to 100 μm.

[0034] In one embodiment, the compression molding pressure is 50 to 200 MPa, such as 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa, 100 MPa, 110 MPa, 120 MPa, 130 MPa, 140 MPa, 150 MPa, 160 MPa, 170 MPa, 180 MPa, 190 MPa, and 200 MPa.

[0035] It should be noted that the molded product is vibrated and sealed before being pressed, and a cold isostatic pressing device is used for the pressing.

[0036] In one embodiment, the die used during extrusion is kept at the same temperature as the aluminum alloy powder body. This not only reduces thermal shock and protects the die, but also helps control product precision and surface quality. It should be noted that the extrusion process can be performed on a hydraulic press.

[0037] In one embodiment, the extrusion ratio during extrusion is 10 to 50, such as 10, 13, 16, 19, 22, 25, 28, 31, 34, 39, 42, 45, 48, or 50. This extrusion ratio can be used to obtain a dense aluminum alloy hot-extruded rod.

[0038] In one embodiment, the aging heat treatment is performed under an inert gas (such as argon), and can be performed in a tube furnace.

[0039] In one embodiment, Figure 2 As shown, the aging heat treatment temperature is 100-300°C (e.g., 100°C, 150°C, 200°C, 250°C, 300°C) and maintained for 10-20 hours (e.g., 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours).

[0040] The heat treatment temperature and time are adjusted within the range of 100-300°C, depending on the precipitation behavior of the strengthening phase in the actual alloy system. Through this aging heat treatment, fine and evenly dispersed strengthening phases can be precipitated in the alloy matrix, which can improve the strength of the aluminum alloy while maintaining good processing properties.

[0041] By optimizing the ratio of alloying elements such as magnesium, silicon and copper, the alloying elements are dissolved as fully as possible in the aluminum-based melt during the smelting process. Subsequently, a rapid cooling atomization powder making process is used to form a supersaturated solid solution in the solidified powder, thereby effectively suppressing the precipitation of coarse second phases and significantly improving the solid solubility and distribution uniformity of the alloying elements in the powder. The obtained aluminum alloy powder is formed by cold isostatic pressing and then hot extruded to obtain a dense rod. Subsequently, aging heat treatment is performed to promote the precipitation of fine, dispersed strengthening phases in the supersaturated solid solution. This process significantly improves the comprehensive mechanical properties of aluminum alloys, especially in terms of strength and plasticity, and is suitable for engineering applications with high requirements for high strength and high toughness.

[0042] An embodiment of the present invention further provides a high-strength and toughness aluminum alloy prepared by the method described above.

[0043] The present invention is further described below with reference to specific embodiments.

[0044] Example 1 This embodiment adopts a method for preparing a high-strength and tough aluminum alloy by powder metallurgy, based on an alloy with a composition of Al~1.0Mg~2.0Si~0.5Cu, specifically including: An aluminum alloy powder with a composition of 1.0% Mg, 2.0% Si, 0.5% Cu, and the remaining Al was prepared by gas atomization, with a particle size range of 0 to 50 μm. The aluminum alloy powder was packed into a rubber bag, vibrated, and sealed. The powder was then pressed into a green body with a certain strength using a cold isostatic press at a pressure of 100 MPa. The green body was wrapped with pure aluminum foil and placed in a box furnace, held at 200°C for 1 hour. The green body was then hot-extruded through a preheated 200°C die steel extrusion nozzle with an extrusion ratio of 16:1 to produce 10 mm Φ aluminum alloy round bars. The aluminum alloy round bars were then placed in an argon-protected tube furnace for aging heat treatment. The temperature was ramped from 50°C to 150°C at a rate of 5°C / min, then held at this temperature for 10 hours before being naturally cooled to room temperature.

[0045] Example 2 This embodiment adopts a method for preparing a high-strength and tough aluminum alloy by powder metallurgy, based on an alloy with a composition of Al~2.0Mg~0.5Si~0.5Cu, specifically including: An aluminum alloy powder with the following composition: Mg: 2.0%; Si: 0.5%; Cu: 0.5%; Al: the remainder, with a particle size range of 0-50 μm, was prepared using a gas atomization method. The aluminum alloy powder was placed in a rubber sheath, vibrated, and sealed. Using a cold isostatic press, the powder was pressed into a green body with a certain strength at a pressure of 100 MPa. The green body was wrapped with pure aluminum foil and placed in a box furnace, held at 200°C for 1 hour. It was then hot-extruded through a preheated 200°C die steel extrusion nozzle with an extrusion ratio of 16:1 to produce a 10 mm Φ aluminum alloy round bar. The aluminum alloy round bar was then placed in an argon atmosphere tube furnace for aging heat treatment. The aging heat treatment consisted of heating from 50°C to 150°C at a heating rate of 5°C / min, holding for 10 hours, and then naturally cooling to room temperature. Example 2 differs from Example 1 in the aluminum alloy composition: the Mg content is higher and the Si content is lower than that of Example 1.

[0046] Example 3 This embodiment adopts a method for preparing a high-strength and tough aluminum alloy by powder metallurgy, based on an alloy with a composition of Al~1.0Mg~2.0Si~0.5Cu, specifically including: An aluminum alloy composition of 1.0% Mg, 2.0% Si, 0.5% Cu, and the remaining aluminum alloy powder was prepared by gas atomization, with a particle size range of 50 to 100 μm. The aluminum alloy powder was placed in a rubber sheath, vibrated, and sealed. The powder was pressed into a dense green body with a certain strength using a cold isostatic pressing device at a pressure of 100 MPa. The green body was wrapped with pure aluminum foil and placed in a box furnace and kept at 200°C for 1 hour. It was then hot extruded through a die steel extrusion nozzle preheated to 200°C with an extrusion ratio of 16:1 to extrude Φ10 mm aluminum alloy round bars. The aluminum alloy round bars were placed in a tubular furnace protected by an argon atmosphere for aging heat treatment, kept at 150°C for 10 hours at a heating rate of 5°C / min, and then naturally cooled to room temperature. The difference between Example 3 and Example 1 is that the particle size of the aluminum alloy powder is different.

[0047] Example 4 This embodiment adopts a method for preparing a high-strength and tough aluminum alloy by powder metallurgy, based on an alloy with a composition of Al~2.0Mg~0.5Si~0.5Cu, specifically including: An aluminum alloy powder with the following composition: Mg: 2.0%; Si: 0.5%; Cu: 0.5%; Al: the remainder, with a particle size range of 50-100 μm, was prepared by gas atomization. The aluminum alloy powder was placed in a rubber sheath, vibrated, and sealed. Using a cold isostatic press, the powder was pressed into a dense, high-strength green body at a pressure of 100 MPa. The green body was wrapped in pure aluminum foil and placed in a box furnace, held at 200°C for 1 hour. It was then hot-extruded through a preheated 200°C die steel extrusion nozzle with an extrusion ratio of 16:1 to produce a 10 mm Φ aluminum alloy round bar. The aluminum alloy round bar was then placed in an argon-protected tubular furnace for aging heat treatment. The aging heat treatment consisted of heating from 50°C to 150°C at a heating rate of 5°C / min, holding for 10 hours, and then naturally cooling to room temperature. Example 4 differs from Example 2 in that the aluminum alloy powder has a different particle size.

[0048] Example 5 This embodiment adopts a method for preparing a high-strength and tough aluminum alloy by powder metallurgy, based on an alloy with a composition of Al~5.0Mg~0.5Si~0.5Cu, specifically including: An aluminum alloy powder with the following composition: Mg: 5.0%; Si: 0.5%; Cu: 0.5%; Al: the remainder, with a particle size range of 0-50 μm, was prepared using a gas atomization method. The aluminum alloy powder was placed in a rubber sheath, vibrated, and sealed. Using a cold isostatic press, the powder was pressed into a dense, high-strength billet at a pressure of 100 MPa. The billet was wrapped in pure aluminum foil and placed in a box furnace, held at 300°C for 1 hour. It was then hot-extruded through a preheated 300°C die steel extrusion nozzle with an extrusion ratio of 16:1 to produce a 10 mm Φ aluminum alloy round bar. The aluminum alloy round bar was then placed in an argon-protected tubular furnace for aging heat treatment. The aging heat treatment consisted of heating from 50°C to 150°C at a rate of 5°C / min, holding for 10 hours, and then naturally cooling to room temperature. Example 5 differs from Example 2 in that the aluminum alloy composition is different, with a higher Mg content compared to Example 2.

[0049] Example 6 This embodiment adopts a method for preparing a high-strength and tough aluminum alloy by powder metallurgy, based on an alloy with a composition of Al~5.0Mg~0.5Si~1.0Cu, specifically including: An aluminum alloy powder with the following composition: Mg: 5.0%; Si: 0.5%; Cu: 1.0%; Al: the remainder, with a particle size range of 0-50 μm, was prepared using a gas atomization method. The aluminum alloy powder was placed in a rubber sheath, vibrated, and sealed. Using a cold isostatic press, the powder was pressed into a dense, high-strength billet at a pressure of 100 MPa. The billet was wrapped in pure aluminum foil and placed in a box furnace, held at 300°C for 1 hour. It was then hot-extruded through a preheated 300°C die steel extrusion nozzle with an extrusion ratio of 16:1 to produce a 10 mm Φ aluminum alloy round bar. The aluminum alloy round bar was then placed in an argon-protected tubular furnace for aging heat treatment. The aging heat treatment consisted of heating from 50°C to 150°C at a rate of 5°C / min, holding for 10 hours, and then naturally cooling to room temperature. Example 6 differs from Example 5 in that the aluminum alloy composition is different, with a higher Cu content compared to Example 5.

[0050] Figure 3 The metallographic images of the conventional 6061 aluminum alloy powder and the aluminum alloy powders of Examples 1 to 6 are shown, wherein (a) is the metallographic image of the conventional 6061 aluminum alloy powder; (b) is the metallographic image of the aluminum alloy powder of Example 1; (c) is the metallographic image of the aluminum alloy powder of Example 2; (d) is the metallographic image of the aluminum alloy powder of Example 3; (e) is the metallographic image of the aluminum alloy powder of Example 4; (f) is the metallographic image of the aluminum alloy powder of Example 5; and (g) is the metallographic image of the aluminum alloy powder of Example 6. Figure 3 As can be seen, the aluminum alloy powder particles are mostly round or nearly spherical, with a relatively regular shape. The powder particles are evenly distributed in the image, with no obvious localized aggregation or uneven dispersion. Figure 3 Figures (b), (c), (f), and (g) show that the majority of particles in Examples 1, 2, 5, and 6 have diameters between 0 and 50 μm. Figures (d) and (e) show that the majority of particles in Examples 3 and 4 have diameters between 50 and 100 μm. The particle surfaces are relatively smooth, with distinct grain boundaries. Small defects such as pores or cracks are visible within some particles. Figure 4 The metallographic images of aluminum alloy rods extruded from conventional 6061 aluminum alloy components and components of Examples 1 to 6 are shown, wherein (a) is a metallographic image of an aluminum alloy rod made of 6061; (b) is a metallographic image of an aluminum alloy rod extruded from Example 1; (c) is a metallographic image of an aluminum alloy rod extruded from Example 2; (d) is a metallographic image of an aluminum alloy rod extruded from Example 3; (e) is a metallographic image of an aluminum alloy rod extruded from Example 4; (f) is a metallographic image of an aluminum alloy rod extruded from Example 5; and (g) is a metallographic image of an aluminum alloy rod extruded from Example 6. Figure 4It can be seen that the metallographic structure of the extruded state is relatively uniform, with fine grains and dispersed second phase particles observed.

[0051] Figure 5 The metallographic images of the rods obtained by using the traditional 6061 aluminum alloy components and the components of Examples 1 to 6 after aging heat treatment; wherein, (a) is the metallographic image of the aluminum alloy rod made of 6061 after aging heat treatment; (b) is the metallographic image of the aluminum alloy rod made in Example 1 after aging heat treatment; (c) is the metallographic image of the aluminum alloy rod made in Example 2 after aging heat treatment; (d) is the metallographic image of the aluminum alloy rod made in Example 3 after aging heat treatment; (e) is the metallographic image of the aluminum alloy rod made in Example 4 after aging heat treatment; (f) is the metallographic image of the aluminum alloy rod made in Example 5 after aging heat treatment; (g) is the metallographic image of the aluminum alloy rod made in Example 6 after aging heat treatment. From Figure 5 As can be seen, the microstructure remains relatively uniform after aging treatment, with no obvious abnormal microstructure or abnormal grain growth. Fine precipitates can be observed in some areas, showing a relatively regular morphology, small size, and dispersion. This suggests that the precipitates after aging treatment may have a certain strengthening effect, thereby improving the alloy's properties.

[0052] Figure 6 The hardness comparison chart of each component in extrusion state and aging state is shown in Figure 2. Figure 6 It can be seen that the hardness of the extruded state of each embodiment is improved compared with that of 6061 aluminum alloy, among which, Example 1: 89.2±0.89; Example 2: 84.68±0.56; Example 3: 94.30±1.0; Example 4: 79.10±1.2; Example 5: 106.85±0.39; Example 6: 105.63±0.45, 6061 aluminum alloy: 74.77±0.83, and the hardness of the extruded state of Example 5 is the highest. After heat treatment, the hardness of Examples 1 to 4 in the aged state is significantly enhanced (Example 1: 98.26±0.76; Example 2: 93.28±1.56; Example 3: 94.00±2.6; Example 4: 81.60±1.4), among which the hardness of Example 1 is the highest, and the hardness of Examples 5 to 6 in the aged state is slightly decreased (Example 5: 98.34±0.82; Example 6: 96.14±0.43).

[0053] Figure 7 The comparison chart of tensile properties of each component in extrusion state is shown in Figure 2. Figure 7The stress-strain curves of the extruded state of each example and the 6061 aluminum alloy are shown. The yield strength and elongation of the 6061 aluminum alloy and each example are: 198.7±2.1MPa, 12.9±0.1%; 215.3±1.5MPa, 11.9±0.9%; 217.3±3.5MPa, 12.0±2.0%; 181.8±2.1MPa, 15.2±0.3%; 199.5±2.2MPa, 14.5±0.5%; 250.6±1.7MPa, 11.9±1.1%; and 244.7±2.7MPa, 13.1±0.2%. The yield strength of Example 5 is the highest compared to 6061. The elongation of Examples 1, 2, and 5 decreases slightly, while the elongation of Examples 3, 4, and 6 increases slightly. Figure 8 The comparison chart of tensile properties of each component in the aging state is shown in Figure 2. Figure 8 The stress-strain curves of the aged state of each example can be seen; the yield strength and elongation of the 6061 aluminum alloy and each example are: 201.4±4.7MPa, 11.8±0.9%; 256.2±2.5MPa, 9.8±0.3%; 246.6±0.7MPa, 10.6±0.5%; 251.1±3.5MPa, 12.4±2.0%; 213.3±2.1MPa, 13.7±0.5%; 248.0±1.4MPa, 12.5±0.6%; and 231.2±2.0MPa, 13.1±1.4%. It can be seen that after heat treatment, the yield strength of Examples 1-4 all increases to a certain extent, while the elongation decreases to a certain extent. Among them, Example 1 has the highest yield strength. The yield strength of Examples 5 and 6 decreases to a certain extent, while the elongation increases.

[0054] In summary, the method for preparing high-strength and toughness aluminum alloy using powder metallurgy provided by the present invention has the following advantages: (1) By optimizing the ratio of alloying elements such as Mg, Si, and Cu, the alloying elements can be dissolved as fully as possible in the aluminum-based melt during the smelting process. This component design breaks through the limitation of the low element content in traditional 6061 aluminum alloy and expands the space for the formation of strengthening phases. The obtained aluminum alloy powder is then pressed and hot-extruded to obtain dense rods. At the same time, combined with the precise control of the subsequent aging heat treatment process, an aluminum alloy material with high strength, high plasticity, and good machinability is obtained. Through aging heat treatment, fine and dispersed strengthening phases are precipitated in the supersaturated solid solution. This method can significantly improve the comprehensive mechanical properties of aluminum alloys, especially in terms of strength and plasticity, and is suitable for engineering applications with high requirements for high strength and high toughness.

[0055] (2) The present invention further adopts a gas atomization method to prepare aluminum alloy powder. The aluminum alloy powder prepared by this method can solidify rapidly. A supersaturated solid solution is formed in the solidified powder, thereby effectively suppressing the precipitation of coarse second phases and significantly improving the solid solubility and distribution uniformity of alloying elements in the powder. A supersaturated solid solution is achieved from the powder making stage, that is, a large amount of solid solution of multiple alloying elements (such as Mg, Si, and Cu) is achieved in the aluminum alloy powder, suppressing the formation of coarse second phases, thereby obtaining a powder supersaturated solid solution with uniform composition distribution and higher strengthening potential.

[0056] (3) Controlling precipitation behavior through low-temperature aging heat treatment. After obtaining a dense material through hot extrusion, aging heat treatment in the range of 100-300°C is performed to slowly precipitate, refine, and disperse strengthening phases such as Mg, Si, Al, and Cu in the alloy, thereby significantly improving the strength of the material and achieving excellent strength-plasticity synergy.

[0057] It should be understood that the application of the present invention is not limited to the above examples. For those skilled in the art, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A method for preparing a high-strength and tough aluminum alloy by powder metallurgy, characterized in that: The steps include: S1. Prepare aluminum alloy powder, wherein the aluminum alloy powder comprises the following components by mass fraction: Mg: 1.0% to 10.0%, Si: 0.5% to 2.0%, Cu: 0.5% to 5.0%, and Al: balance; S2, pressing the aluminum alloy powder into a shape to form an aluminum alloy powder blank; S3, heating the aluminum alloy powder body to 100-300° C. and keeping the temperature for 0.5-1 hour, and then extruding it into an aluminum alloy rod; S4. Performing aging heat treatment on the aluminum alloy bar to obtain a high-strength and toughness aluminum alloy.

2. The method for preparing a high-strength and tough aluminum alloy by powder metallurgy according to claim 1, characterized in that: Aluminum alloy powder was prepared by gas atomization method.

3. The method for preparing a high-strength and tough aluminum alloy by powder metallurgy according to claim 2, characterized in that: The particle size of the aluminum alloy powder is less than 100 μm.

4. The method for preparing a high-strength and tough aluminum alloy by powder metallurgy according to claim 1, characterized in that: The pressure of the pressing molding is 50 to 200 MPa.

5. The method for preparing a high-strength and tough aluminum alloy by powder metallurgy according to claim 1, characterized in that: The temperature of the die and the aluminum alloy powder body used during extrusion are consistent.

6. The method for preparing a high-strength and tough aluminum alloy by powder metallurgy according to claim 1, characterized in that: The extrusion ratio during extrusion is 10 to 50.

7. The method for preparing a high-strength and tough aluminum alloy by powder metallurgy according to claim 1, characterized in that: The aging heat treatment is performed under an inert gas.

8. The method for preparing a high-strength and tough aluminum alloy by powder metallurgy according to claim 1, characterized in that: The aging heat treatment temperature is maintained at 100-300° C. for 10-20 hours.

9. A high-strength and tough aluminum alloy, characterized in that: Prepared by the method according to any one of claims 1 to 8.

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