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

Abstract

The application discloses high-toughness aluminum alloy and a method for preparing the same by adopting a powder metallurgy method, and relates to the field of aluminum alloy material preparation.The method comprises the following steps: preparing an aluminum alloy powder, wherein the aluminum alloy powder comprises the following components in mass fraction: Mg: 1.0%-10.0%, Si: 0.5%-2.0%, Cu: 0.5%-5.0%, and Al: the balance; preparing an aluminum alloy powder blank; being heated to 100-300 DEG C and being kept for 0.5-1 hours, and then being extruded into an aluminum alloy rod; and being subjected to aging heat treatment.The application optimizes the proportion of alloy elements, so that the alloy elements can be dissolved in an aluminum base melt as fully as possible in a melting process, the components expand the forming space of a strengthening phase, and the components are combined with the accurate control in a subsequent heat treatment process, so that the aluminum alloy material has high strength, high plasticity and good machining performance.

Description

TECHNICAL FIELD

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

[0002] Aluminum alloys have wide application value in the fields of aerospace, transportation, electronic products, etc. due to their light weight, high specific strength, excellent corrosion resistance and processing adaptability. In the consumer electronics field, not only high-strength materials are needed to meet the durability requirements, but also excellent plasticity is needed to adapt to complex processing technology, and strict requirements are also placed on surface performance (such as anodizing performance, polishing performance) and corrosion resistance. Al-Zn series and Al-Cu series aluminum alloys represented by high strength have poor ductility and unsatisfactory corrosion resistance, so their application in consumer products is limited. 6 series aluminum alloys have good machinability, formability and corrosion resistance, and also have medium strength. The traditional 6061 aluminum alloy includes the following components by mass fraction: Mg: 0.8% to 1.2%; Si: 0.4% to 0.8%; Cu: 0.15% to 0.4%; Mn: 0.15%; Fe: 0.7%; Cr: 0.04% to 0.35%; Zn: 0.25%; Ti: 0.15%; and Al: balance. The content of solid solution elements in the traditional 6061 aluminum alloy is low, so the potential for improving mechanical properties is limited, and therefore there is an urgent need to prepare new aluminum alloy materials with better mechanical properties by new methods.

[0003] Currently, the method for realizing the strength and toughness of aluminum alloys is mainly achieved by alloying treatment. On the one hand, the proportion of main alloying elements is adjusted or other solid solution elements are added, and on the other hand, micro-alloying can be achieved by adding other elements (such as rare earth elements). The Chinese patent with application number 202211310467.7 uses pure Al powder as the main raw material, and introduces elements such as Zr and Re in the form of elemental powder or simple intermediate alloy powder. After the raw material powder is uniformly mixed in a certain proportion, an aluminum alloy part is obtained through processes such as compaction molding, sintering and heat treatment. However, the toughness of the aluminum alloy prepared by this method is not ideal, the matching degree of strength and toughness is poor, and the cost of the added alloying elements is high. The Chinese patent with application number 201711098167.6 uniformly mixes pure Al powder and Mg, Si and Cu alloying element powders or binary alloy powders in a certain proportion, and then obtains an aluminum alloy part through processes such as compaction molding, sintering, heat treatment and subsequent surface treatment. This method simplifies the production process, improves production efficiency and reduces production cost, but the alloy strength improvement effect is not ideal and the plasticity is poor.

[0004] Therefore, the prior art still needs to be improved and developed. SUMMARY

[0005] In view of the above deficiencies of the prior art, the purpose of the present application is to provide a high-toughness aluminum alloy and a method for preparing the high-toughness aluminum alloy by adopting a powder metallurgy method, aiming to improve the comprehensive performance of the aluminum alloy, so that the aluminum alloy has higher strength and toughness.

[0006] The technical scheme of the present application is as follows:

[0007] In the first aspect of the present application, a method for preparing a high-toughness aluminum alloy by adopting a powder metallurgy method is provided, comprising the following steps:

[0008] S1, preparing an aluminum alloy powder, the aluminum alloy powder comprising the following components in mass fraction: Mg: 1.0% to 10.0%, Si: 0.5% to 2.0%, Cu: 0.5% to 5.0%, and Al: the balance;

[0009] S2, pressing and forming the aluminum alloy powder into an aluminum alloy powder blank;

[0010] S3, heating the aluminum alloy powder blank to 100 to 300 DEG C and keeping the temperature for 0.5 to 1 hour, and then extruding the aluminum alloy powder blank into an aluminum alloy rod;

[0011] S4, performing aging heat treatment on the aluminum alloy rod.

[0012] Optionally, the aluminum alloy powder is prepared by adopting a gas atomization method.

[0013] Optionally, the particle size of the aluminum alloy powder is less than 100 mu m.

[0014] Optionally, the pressure for pressing and forming is 50 to 200 MPa.

[0015] Optionally, the temperature of the die and the aluminum alloy powder blank is consistent when extruding.

[0016] Optionally, the extrusion ratio when extruding is 10 to 50.

[0017] Optionally, the aging heat treatment is performed under an inert gas.

[0018] Optionally, the temperature of the aging heat treatment is 100 to 300 DEG C for 10 to 20 hours.

[0019] In the second aspect of the present application, a high-toughness aluminum alloy is provided, which is prepared by the method.

[0020] Beneficial effects:

[0021] (1) The present application optimizes the proportion of alloying elements such as Mg, Si and Cu, so that the alloying elements can be fully dissolved in the aluminum-based melt as much as possible during the smelting process. The component design breaks through the limitation of low element content in the traditional 6061 aluminum alloy, expands the formation space of the strengthening phase, and then the obtained aluminum alloy powder is pressed into a compact rod, and then subjected to heat extrusion, so that a compact rod is obtained. Combined with the precise control of the subsequent aging heat treatment process, an aluminum alloy material with high strength and high plasticity, good machining performance is obtained. Through aging heat treatment, fine and dispersed strengthening phase is precipitated in the supersaturated solid solution. The method can significantly improve the comprehensive mechanical properties of the aluminum alloy, especially in strength and plasticity, and is suitable for engineering application scenarios with high requirements for high strength and high toughness performance.

[0022] (2) The present application further adopts the gas atomization method to prepare the aluminum alloy powder, and the aluminum alloy powder prepared by the method can be rapidly solidified. The supersaturated solid solution is formed in the solidified powder, thereby effectively inhibiting the precipitation of coarse second phase and significantly improving the solid solubility and distribution uniformity of alloying elements in the powder. The supersaturated solid solution is realized from the powder preparation stage, that is, a large amount of solid solution of various alloying elements (such as Mg, Si and Cu) in the aluminum alloy powder is realized, and the formation of coarse second phase is inhibited, so that a powder supersaturated solid solution with uniform composition distribution and higher strengthening potential can be obtained.

[0023] (3) The precipitation behavior is controlled by low-temperature aging heat treatment. After the compact material is obtained by heat extrusion, the aging heat treatment in the range of 100-300 DEG C is carried out, so that the strengthening phase such as Mg, Si, Al and Cu in the alloy is slowly precipitated and refined and dispersedly distributed, thereby significantly improving the strength of the material and realizing excellent strength-plasticity synergy. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The flow chart of the present application.

[0025] Figure 2 The schematic diagram of the aging heat treatment of the present application.

[0026] Figure 3 The metallographic photographs of the traditional 6061 aluminum alloy powder and the aluminum alloy powders of examples 1-6, wherein (a) is the metallographic photograph of the traditional 6061 aluminum alloy powder; (b) is the metallographic photograph of the aluminum alloy powder of example 1; (c) is the metallographic photograph of the aluminum alloy powder of example 2; (d) is the metallographic photograph of the aluminum alloy powder of example 3; (e) is the metallographic photograph of the aluminum alloy powder of example 4; (f) is the metallographic photograph of the aluminum alloy powder of example 5; (g) is the metallographic photograph of the aluminum alloy powder of example 6.

[0027] Figure 4Microstructure of aluminum alloy rods extruded from the conventional 6061 aluminum alloy composition and the compositions of Examples 1-6, wherein (a) is the microstructure of the aluminum alloy rod made from 6061; (b) is the microstructure of the aluminum alloy rod made from Example 1; (c) is the microstructure of the aluminum alloy rod made from Example 2; (d) is the microstructure of the aluminum alloy rod made from Example 3; (e) is the microstructure of the aluminum alloy rod made from Example 4; (f) is the microstructure of the aluminum alloy rod made from Example 5; and (g) is the microstructure of the aluminum alloy rod made from Example 6.

[0028] Figure 5 Microstructure of the rods made from the conventional 6061 aluminum alloy composition and the compositions of Examples 1-6 after aging heat treatment, wherein (a) is the microstructure of the aluminum alloy rod made from 6061 after aging heat treatment; (b) is the microstructure of the aluminum alloy rod made from Example 1 after aging heat treatment; (c) is the microstructure of the aluminum alloy rod made from Example 2 after aging heat treatment; (d) is the microstructure of the aluminum alloy rod made from Example 3 after aging heat treatment; (e) is the microstructure of the aluminum alloy rod made from Example 4 after aging heat treatment; (f) is the microstructure of the aluminum alloy rod made from Example 5 after aging heat treatment; and (g) is the microstructure of the aluminum alloy rod made from Example 6 after aging heat treatment.

[0029] Figure 6 Comparison chart of the hardness of the extruded state and the aged state of each composition.

[0030] Figure 7 Comparison chart of the tensile properties of the extruded state of each composition.

[0031] Figure 8 Comparison chart of the tensile properties of the aged state of each composition. DETAILED DESCRIPTION

[0032] The present application provides a high-toughness aluminum alloy and a method for preparing the high-toughness aluminum alloy by using a powder metallurgy method. In order to make the purpose, technical scheme and effects of the present application more clear and explicit, the present application is further described in detail below. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0033] The content of alloying elements in the conventional 6061 aluminum alloy is low, and it is generally believed by those skilled in the art that a lower content of alloying elements makes the alloy have better plasticity and toughness, is easy to process, and has good welding performance and corrosion resistance. Too high content of alloying elements can easily lead to element segregation, affecting the uniformity of the material, and adding a large amount of alloying elements can also increase the cost. However, the content of solid solution elements in the conventional 6061 aluminum alloy is low, so the potential for improving the mechanical properties is limited, and therefore there is an urgent need to prepare new aluminum alloy materials with better mechanical properties by new methods.

[0034] The embodiment of the present application provides a method for preparing high-strength and high-toughness aluminum alloy by adopting a powder metallurgy method, as shown in the following steps. Figure 1

[0035] S1, preparing aluminum alloy powder, the aluminum alloy powder comprising the following components in mass fraction: Mg: 1.0%-10.0%, Si: 0.5%-2.0%, Cu: 0.5%-5.0%, and Al: the balance;

[0036] S2, pressing the aluminum alloy powder into a shape to form an aluminum alloy powder blank;

[0037] S3, heating the aluminum alloy powder blank to 100-300 DEG C and keeping the temperature for 0.5-1 hours, and then extruding the aluminum alloy powder blank into an aluminum alloy rod;

[0038] S4, performing aging heat treatment on the aluminum alloy rod.

[0039] The embodiment of the present application breaks through the limitation of low content of elements in traditional 6061 aluminum alloy by optimizing the proportion of alloying elements such as Mg, Si and Cu, so that the alloying elements can be dissolved in the aluminum base melt as much as possible in the melting process, expands the forming space of the strengthening phase, and then the obtained aluminum alloy powder is pressed into a shape and then heat-extruded to obtain a dense aluminum alloy rod, and the accurate control in the subsequent aging heat treatment process is combined to obtain an aluminum alloy material with high strength and high plasticity and good machining performance. Through the aging heat treatment, the fine and dispersed strengthening phase is precipitated from the supersaturated solid solution. The method can significantly improve the comprehensive mechanical properties of the aluminum alloy, especially the strength and plasticity, and is suitable for engineering application scenarios with high requirements for high-strength and high-toughness performance.

[0040] In one embodiment, the aluminum alloy powder is prepared by adopting a gas atomization method.

[0041] It should be noted that the preparation method of the aluminum alloy powder prepared by the gas atomization method can be summarized as follows: the alloy raw materials are completely melted and uniformly mixed to form an aluminum alloy melt. The melted aluminum alloy melt is introduced into an atomization chamber, the liquid metal stream is broken into small droplets by using high-speed airflow, and then the aluminum alloy powder is obtained by rapid cooling and solidification.

[0042] ​The aluminum alloy powder prepared using this method can solidify rapidly. A supersaturated solid solution forms in the solidified powder, effectively suppressing the precipitation of coarse second phases and significantly improving the solid solubility and uniformity of alloying elements in the powder. Achieving a supersaturated solid solution from the powder preparation stage—that is, achieving a large amount of solid solution of multiple alloying elements (such as Mg, Si, Cu) in the aluminum alloy powder—suppresses the formation of coarse second phases, thus obtaining a powder supersaturated solid solution with uniform composition distribution and higher strengthening potential.

[0043] In one embodiment, the aluminum alloy powder has a particle size of less than 100 μm. Specifically, aluminum alloy powder with a particle size of 0–50 μm or 50–100 μm can be used.

[0044] In one embodiment, the compression molding pressure is 50 to 200 MPa, for example, 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, or 200 MPa.

[0045] It should be noted that the material is vibrated and sealed before pressing and molding, and a cold isostatic pressing device is used during the pressing process.

[0046] In one embodiment, the temperature of the die and the aluminum alloy powder preform used during extrusion is the same. This not only reduces thermal shock and protects the die, but also allows for control over product precision and surface quality. It should be noted that the extrusion process can be completed on a hydraulic press.

[0047] In one embodiment, the extrusion ratio during extrusion is 10 to 50, for example, 10, 13, 16, 19, 22, 25, 28, 31, 34, 39, 42, 45, 48, or 50. Using this extrusion ratio yields dense hot-extruded aluminum alloy bars.

[0048] In one embodiment, the aging heat treatment is performed under an inert gas (such as argon). Specifically, the aging heat treatment can be performed in a tube furnace.

[0049] In one implementation, such as Figure 2 As shown, the aging heat treatment is carried out at a temperature of 100-300℃ (e.g., 100℃, 150℃, 200℃, 250℃, 300℃) 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).

[0050] According to the precipitation behavior of the strengthening phase in the actual alloy system, the heat treatment temperature and time are adjusted in the range of 100-300 DEG C. Through the aging heat treatment, fine and uniform dispersed strengthening phase can be precipitated in the alloy matrix, which can improve the strength of the aluminum alloy while maintaining good processing performance.

[0051] By optimizing the proportion of alloying elements such as magnesium, silicon and copper, the alloying elements are dissolved in the aluminum melt as much as possible during smelting, and then a supersaturated solid solution is formed in the solidified powder by using a rapid cooling atomization powdering process, thereby effectively inhibiting the precipitation of coarse second phase and significantly improving the solid solubility and distribution uniformity of alloying elements in the powder. The obtained aluminum alloy powder is cold isostatic pressed and then heat extruded to obtain a dense rod. Then, through aging heat treatment, fine and dispersed strengthening phase is precipitated from the supersaturated solid solution. The process significantly improves the comprehensive mechanical properties of the aluminum alloy, especially in strength and plasticity, and is suitable for engineering application scenarios with high requirements for high strength and high toughness performance.

[0052] The embodiment of the present application also provides a high-strength and high-toughness aluminum alloy prepared by the method.

[0053] The present application is further described below in conjunction with specific embodiments.

[0054] Embodiment 1

[0055] The embodiment adopts a powder metallurgy method to prepare a high-strength and high-toughness aluminum alloy, which is based on an alloy with a composition of Al-1.0Mg-2.0Si-0.5Cu and specifically includes the following steps:

[0056] An aluminum alloy with a composition of Mg: 1.0%; Si: 2.0%; Cu: 0.5%; and Al: the rest is prepared by using a gas atomization method, and the particle size range is 0-50 μm. The aluminum alloy powder is vibrated and sealed in a rubber jacket, and a cold isostatic pressing device is used to press the powder into a certain strength green body under a pressure of 100 MPa. The green body is wrapped with pure aluminum foil, placed in a box furnace and heated at 200 DEG C for 1 hour, and then extruded through a die steel extrusion nozzle preheated to 200 DEG C, with an extrusion ratio of 16:1, to obtain an aluminum alloy round rod with a diameter of Φ10 mm. The aluminum alloy round rod is placed in a tube furnace protected by argon atmosphere for aging heat treatment, and the aging heat treatment is as follows: the temperature is raised from 50 DEG C to 150 DEG C at a rate of 5 DEG C / min, then kept for 10 hours, and then naturally cooled to room temperature.

[0057] Embodiment 2

[0058] The embodiment adopts a powder metallurgy method to prepare a high-strength and high-toughness aluminum alloy, which is based on an alloy with a composition of Al-2.0Mg-0.5Si-0.5Cu and specifically includes the following steps:

[0059] Aluminum alloy composition: Mg: 2.0%; Si: 0.5%; Cu: 0.5%; Al: the rest of the aluminum alloy powder, particle size range of 0-50 μm. The aluminum alloy powder is packed into a rubber jacket, vibrated and sealed, and a cold isostatic pressing device is used to press the powder into a certain strength green body under a pressure of 100 MPa. The green body is wrapped with pure aluminum foil and placed in a box furnace and heat treated at 200°C for 1 hour, and then hot extruded through a preheated to 200°C die steel extrusion nozzle with an extrusion ratio of 16:1 to extrude a Φ10 mm aluminum alloy round bar. The aluminum alloy round bar is placed in a tube furnace protected by argon atmosphere for aging heat treatment, and the aging heat treatment is as follows: the temperature is raised from 50°C to 150°C at a rate of 5°C / min, then kept for 10 hours, and then naturally cooled to room temperature. The difference between Example 2 and Example 1 is that the aluminum alloy composition is different, the Mg content is more than that of Example 1, and the Si content is less than that of Example 1.

[0060] Example 3

[0061] The method for preparing high strength and toughness aluminum alloy by powder metallurgy in this embodiment is based on the preparation of an alloy with a composition of Al-1.0Mg-2.0Si-0.5Cu, which specifically includes:

[0062] Aluminum alloy composition: Mg: 1.0%; Si: 2.0%; Cu: 0.5%; Al: the rest of the aluminum alloy powder, particle size range of 50-100 μm. The aluminum alloy powder is packed into a rubber jacket, vibrated and sealed, and a cold isostatic pressing device is used to press the powder into a certain strength green body under a pressure of 100 MPa. The green body is wrapped with pure aluminum foil and placed in a box furnace and heat treated at 200°C for 1 hour, and then hot extruded through a preheated to 200°C die steel extrusion nozzle with an extrusion ratio of 16:1 to extrude a Φ10 mm aluminum alloy round bar. The aluminum alloy round bar is placed in a tube furnace protected by argon atmosphere for aging heat treatment, and the aging heat treatment is as follows: the temperature is raised from 50°C to 150°C at a rate of 5°C / min, then kept for 10 hours, 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.

[0063] Example 4

[0064] The method for preparing high strength and toughness aluminum alloy by powder metallurgy in this embodiment is based on the preparation of an alloy with a composition of Al-2.0Mg-0.5Si-0.5Cu, which specifically includes:

[0065] Aluminum alloy powder with composition: Mg: 2.0%; Si: 0.5%; Cu: 0.5%; Al: balance is prepared by gas atomization method, and the particle size range is 50-100 μm. The aluminum alloy powder is vibrated and sealed in a rubber jacket, and a cold isostatic pressing device is used to press the powder into a compacted body with certain strength under a pressure of 100 MPa. The compacted body is wrapped with pure aluminum foil and placed in a box furnace and heat treated at 200 °C for 1 hour, and then hot extruded through a preheated to 200 °C die steel extrusion nozzle with an extrusion ratio of 16:1 to extrude a Φ10 mm aluminum alloy round bar. The aluminum alloy round bar is placed in a tube furnace protected by argon atmosphere for aging heat treatment, and the aging heat treatment is: heating from 50 °C to 150 °C at a heating rate of 5 °C / min, then holding for 10 hours, and then naturally cooling to room temperature. The difference between Example 4 and Example 2 is that the particle size of the aluminum alloy powder is different.

[0066] Example 5

[0067] The method for preparing high strength and toughness aluminum alloy by powder metallurgy in this example is based on the preparation of an alloy with composition Al-5.0Mg-0.5Si-0.5Cu, and specifically includes:

[0068] Aluminum alloy powder with composition: Mg: 5.0%; Si: 0.5%; Cu: 0.5%; Al: balance is prepared by gas atomization method, and the particle size range is 0-50 μm. The aluminum alloy powder is vibrated and sealed in a rubber jacket, and a cold isostatic pressing device is used to press the powder into a compacted body with certain strength under a pressure of 100 MPa. The compacted body is wrapped with pure aluminum foil and placed in a box furnace and heat treated at 300 °C for 1 hour, and then hot extruded through a preheated to 300 °C die steel extrusion nozzle with an extrusion ratio of 16:1 to extrude a Φ10 mm aluminum alloy round bar. The aluminum alloy round bar is placed in a tube furnace protected by argon atmosphere for aging heat treatment, and the aging heat treatment is: heating from 50 °C to 150 °C at a heating rate of 5 °C / min, then holding for 10 hours, and then naturally cooling to room temperature. The difference between Example 5 and Example 2 is that the aluminum alloy composition is different, and the Mg content is relatively more than that of Example 2.

[0069] Example 6

[0070] The method for preparing high strength and toughness aluminum alloy by powder metallurgy in this example is based on the preparation of an alloy with composition Al-5.0Mg-0.5Si-1.0Cu, and specifically includes:

[0071] Aluminum alloy powder with composition: Mg: 5.0%; Si: 0.5%; Cu: 1.0%; Al: balance was prepared by gas atomization method with particle size range of 0-50 μm. The aluminum alloy powder was packed into rubber sleeve, vibrated and sealed, and then pressed into a compacted body with certain strength under 100 MPa pressure using cold isostatic pressing equipment. The compacted body was wrapped with pure aluminum foil and put into a box furnace and kept at 300 °C for 1 hour, and then hot extruded through an extrusion nozzle of preheated die steel at 300 °C with extrusion ratio of 16:1 to form an aluminum alloy round bar with Φ10 mm. The aluminum alloy round bar was put into a tube furnace in argon environment for aging heat treatment, and the aging heat treatment was as follows: the temperature was raised from 50 °C to 150 °C at a rate of 5 °C / min, then kept for 10 hours, and then naturally cooled to room temperature. The difference between Example 6 and Example 5 is that the aluminum alloy composition is different, and the Cu content is relatively more than that of Example 5.

[0072] Figure 3 Metallographic photos of traditional 6061 aluminum alloy powder and aluminum alloy powder of Examples 1-6, wherein (a) is the metallographic photo of traditional 6061 aluminum alloy powder; (b) is the metallographic photo of aluminum alloy powder of Example 1; (c) is the metallographic photo of aluminum alloy powder of Example 2; (d) is the metallographic photo of aluminum alloy powder of Example 3; (e) is the metallographic photo of aluminum alloy powder of Example 4; (f) is the metallographic photo of aluminum alloy powder of Example 5; (g) is the metallographic photo of aluminum alloy powder of Example 6. It can be seen from the photos that most of the aluminum alloy powder particles are round or approximately spherical in shape, and the shape is relatively regular. The powder particles are uniformly distributed in the photos, and there is no obvious local aggregation or uneven dispersion phenomenon. Figure 3 It can be seen from the photos that most of the aluminum alloy powder particles are round or approximately spherical in shape, and the shape is relatively regular. The powder particles are uniformly distributed in the photos, and there is no obvious local aggregation or uneven dispersion phenomenon. Figure 3 Photos (b), (c), (f) and (g) in FIG. 1 show that the diameters of most of the particles of Examples 1 and 2, and Examples 5 and 6 are between 0-50 μm; (d) and (e) show that the diameters of most of the particles of Examples 3 and 4 are between 50-100 μm. The particle surface is relatively smooth, and obvious grain boundary structure is observed. Some small pores or cracks and other defects can be seen in the interior of some particles.

[0073] Figure 4 Metallographic photos of aluminum alloy round bars extruded from traditional 6061 aluminum alloy composition and the composition of Examples 1-6, wherein (a) is the metallographic photo of aluminum alloy round bar made of 6061; (b) is the metallographic photo of aluminum alloy round bar extruded from Example 1; (c) is the metallographic photo of aluminum alloy round bar extruded from Example 2; (d) is the metallographic photo of aluminum alloy round bar extruded from Example 3; (e) is the metallographic photo of aluminum alloy round bar extruded from Example 4; (f) is the metallographic photo of aluminum alloy round bar extruded from Example 5; (g) is the metallographic photo of aluminum alloy round bar extruded from Example 6. It can be seen from the photos that most of the aluminum alloy powder particles are round or approximately spherical in shape, and the shape is relatively regular. The powder particles are uniformly distributed in the photos, and there is no obvious local aggregation or uneven dispersion phenomenon. Figure 4It can be seen that the extruded metallographic structure is relatively uniform, with fine grains and dispersed second-phase particles observed.

[0074] Figure 5 Metallographic images of bars obtained using conventional 6061 aluminum alloy components and the components of Examples 1-6 after aging heat treatment are shown below; wherein, (a) is a metallographic image of an aluminum alloy bar made of 6061 after aging heat treatment; (b) is a metallographic image of an aluminum alloy bar made in Example 1 after aging heat treatment; (c) is a metallographic image of an aluminum alloy bar made in Example 2 after aging heat treatment; (d) is a metallographic image of an aluminum alloy bar made in Example 3 after aging heat treatment; (e) is a metallographic image of an aluminum alloy bar made in Example 4 after aging heat treatment; (f) is a metallographic image of an aluminum alloy bar made in Example 5 after aging heat treatment; and (g) is a metallographic image of an aluminum alloy bar made in Example 6 after aging heat treatment. Figure 5 It can be seen that the microstructure remains relatively uniform after aging heat treatment, without any obvious abnormal microstructure or abnormal grain growth. Fine precipitate particles can be observed in some areas; these particles are relatively regular in shape, small in size, and dispersed. This suggests that the precipitates after aging heat treatment may have a certain strengthening effect, thereby improving the alloy's properties.

[0075] Figure 6 A comparison chart of the hardness of each component in the extruded and aged states, from... Figure 6 It can be seen that the hardness of the extruded state in each embodiment is improved compared with that of 6061 aluminum alloy. Specifically, the hardness of Example 1 is 89.2±0.89; Example 2 is 84.68±0.56; Example 3 is 94.30±1.0; Example 4 is 79.10±1.2; Example 5 is 106.85±0.39; Example 6 is 105.63±0.45, and that of 6061 aluminum alloy is 74.77±0.83. The hardness of the extruded state in Example 5 is the highest. After heat treatment, the hardness of the aged states of Examples 1-4 was 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), with Example 1 showing the highest hardness increase. The hardness of the aged states of Examples 5-6 decreased slightly (Example 5: 98.34±0.82; Example 6: 96.14±0.43).

[0076] Figure 7 This is a comparison chart of the tensile properties of each component in the extruded state, from... Figure 7It can be seen that the stress-strain curves of each embodiment and 6061 aluminum alloy; the yield strength and elongation of 6061 aluminum alloy and each embodiment are respectively: 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%; 244.7±2.7MPa, 13.1±0.2%. The yield strength of embodiment 5 is the highest compared with 6061, and the elongation of embodiment 1, embodiment 2 and embodiment 5 has a certain decrease, and the elongation of embodiment 3, embodiment 4 and embodiment 6 has a certain increase. Figure 8 The tensile properties of each component in the aging state are compared, and the tensile properties of each component in the aging state are compared. Figure 8 It can be seen that the stress-strain curves of each embodiment in the aging state; the yield strength and elongation of 6061 aluminum alloy and each embodiment are respectively: 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%; 231.2±2.0MPa, 13.1±1.4%. It can be seen that after heat treatment, the yield strength of embodiments 1-4 has a certain increase, and the elongation has a certain decrease, wherein the yield strength of embodiment 1 is the highest, and the yield strength of embodiments 5 and 6 has a certain decrease, and the elongation is improved.

[0077] In summary, the method for preparing high strength and toughness aluminum alloy by adopting powder metallurgy provided by the application has the following advantages:

[0078] (1) By optimizing the proportion of Mg, Si and Cu and other alloy elements, the alloy elements can be dissolved in the aluminum-based melt as much as possible during the melting process. The component design breaks through the limitation of low element content in traditional 6061 aluminum alloy, expands the formation space of the strengthening phase, and then the obtained aluminum alloy powder is pressed into a dense rod, and then subjected to heat extrusion, and combined with the precise control of the subsequent aging heat treatment process, an aluminum alloy material with high strength and high plasticity and good machining performance is obtained. Through aging heat treatment, fine and dispersed strengthening phases are precipitated from the supersaturated solid solution. The method can significantly improve the comprehensive mechanical properties of the aluminum alloy, especially in strength and plasticity, and is suitable for engineering application scenarios with high requirements for high strength and toughness performance.

[0079] (2) The present application further adopts the gas atomization method to prepare the aluminum alloy powder, and the aluminum alloy powder prepared by the method can be rapidly solidified. A supersaturated solid solution is formed in the solidified powder, thereby effectively inhibiting the precipitation of coarse second phases and significantly improving the solid solubility and distribution uniformity of alloy elements in the powder. The supersaturated solid solution is realized from the powdering stage, that is, a large amount of solid solution of various alloy elements (such as Mg, Si, Cu) is realized in the aluminum alloy powder, the formation of coarse second phases is inhibited, and therefore a powder supersaturated solid solution with uniform composition distribution and higher strengthening potential can be obtained.

[0080] (3) The precipitation behavior is controlled by low-temperature aging heat treatment. After obtaining the dense material by hot extrusion, the aging heat treatment in the range of 100-300℃ is performed to make the strengthening phases such as Mg, Si, Al, Cu and the like slowly precipitate and finely and dispersively distribute, thereby significantly improving the strength of the material and realizing excellent strength and ductility synergy.

[0081] It should be understood that the application of the present application is not limited to the above examples, and those skilled in the art can make improvements or changes according to the above description, and all these improvements and changes shall belong to the protection scope of the appended claims of the present application.

Claims

1. A method for preparing high-strength and high-toughness aluminum alloys using powder metallurgy, characterized in that, Includes the following steps: S1. Aluminum alloy powder with a particle size of less than 100 μm is prepared by gas atomization. The aluminum alloy powder has the following composition by mass fraction: Mg: 5.0%, Si: 0.5%, Cu: 0.5%, Al: balance; or Mg: 5.0%, Si: 0.5%, Cu: 1.0%, Al: balance. S2. Press the aluminum alloy powder into shape under a pressure of 50-200MPa to form an aluminum alloy powder blank; S3. The aluminum alloy powder blank is heated to 100-300°C and held for 0.5-1 hour. Then, using a mold with the same temperature as the aluminum alloy powder blank, it is extruded into aluminum alloy rods at an extrusion ratio of 10-50. S4. Under inert gas, the aluminum alloy bar is subjected to aging heat treatment at 100-300°C for 10-20 hours to obtain a high-strength and high-toughness aluminum alloy.

2. A high-strength and high-toughness aluminum alloy, characterized in that, Prepared by the method described in claim 1.

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