Rare earth modified 6061 aluminum alloy material and preparation method thereof

Abstract

The invention provides a rare earth modified 6061 aluminum alloy material and a preparation method thereof.The rare earth modified 6061 aluminum alloy material is prepared from, by mass, 0.1%-0.5% of rare earth elements, 0.1%-0.4% of Al-Ti-B intermediate alloy, 0.05%-0.1% of Al-Mg-Zr intermediate alloy and the balance 6061 aluminum alloy base material, and the rare earth elements comprise La and / or Ce. By adding the low-cost La and / or Ce light rare earth, the Al-Ti-B intermediate alloy and the Al-Mg-Zr intermediate alloy, grains can be refined, the microstructure can be optimized, the adverse effect of a Fe impurity phase can be reduced, the tensile strength, the ductility and other mechanical properties of the material are improved, meanwhile, the production cost is reduced, the application limitation of high-price rare earth is broken through, large-scale production is adapted, and the requirement of the high-end field is met.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy technology, and more specifically, to a rare earth modified 6061 aluminum alloy material and its preparation method. Background Technology

[0002] 6061 aluminum alloy is a typical Al-Mg-Si heat-treatable aluminum alloy. With its excellent machinability, good weldability, and reliable corrosion resistance, it is gradually replacing traditional automotive steels and becoming a crucial material for manufacturing key automotive components. Because of the increasingly widespread application of 6061 aluminum alloy in high-end industrial fields such as aerospace and automotive manufacturing, more stringent requirements are being placed on its mechanical properties.

[0003] Grain refinement and rare-earth alloying are currently mainstream alloy strengthening methods and effective ways to improve the mechanical properties of aluminum alloys. Current research on 6061 rare-earth aluminum alloys mainly focuses on adding heavy rare-earth elements such as Sc, Y, and Er, with particular emphasis on the high-cost rare-earth element Sc. Although rare-earth Sc is currently the microalloying element with the best known strengthening effect, its high cost limits its large-scale application in conventional aluminum alloy products.

[0004] Therefore, there is an urgent need to develop a low-cost, high-performance 6061 aluminum alloy material that can not only meet the application needs of high-end fields, but also has the feasibility of low price, abundant raw material resources, and large-scale production. Summary of the Invention

[0005] The main objective of this invention is to provide a rare earth modified 6061 aluminum alloy material and its preparation method, so as to at least solve the problems in the prior art where the rare earth modification of 6061 aluminum alloy mainly relies on high-cost heavy rare earth elements, resulting in high production costs, difficulty in large-scale production, and inability to simultaneously achieve mechanical property improvement and cost control.

[0006] To achieve the above objectives, the first aspect of the present invention provides a rare earth modified 6061 aluminum alloy material, comprising the following raw materials by mass percentage: 0.1-0.5% rare earth elements, 0.1-0.4% Al-Ti-B master alloy, 0.05-0.1% Al-Mg-Zr master alloy, with the balance being 6061 aluminum alloy substrate, wherein the rare earth elements include La and / or Ce.

[0007] Optionally, the mass ratio of Ce to La in the rare earth elements is (1-2):1; The mass percentage of rare earth elements in the Al-Ti-B master alloy is 2:(1-4).

[0008] A second aspect of this invention provides a method for preparing rare-earth modified 6061 aluminum alloy material, applicable to the rare-earth modified 6061 aluminum alloy material described in this invention, comprising: Preparation of Al-La rare earth master alloys and preparation of Al-Ce rare earth master alloys; The Al-La rare earth master alloy, Al-Ce rare earth master alloy, Al-Ti-B master alloy, and Al-Mg-Zr master alloy were preheated at 250-300℃ for 1 hour. After the 6061 aluminum alloy substrate is placed in a melting furnace and heated to 750℃ to melt, preheated Al-La rare earth master alloy, Al-Ce rare earth master alloy and Al-Ti-B master alloy are added, and then the temperature is held for 10 minutes. Then Al-Mg-Zr master alloy and refining agent are added in sequence. After refining, the slag is removed. After removing the slag, continue heating until the alloy liquid temperature stabilizes at 760-770℃. First, pour the alloy liquid into a metal mold preheated to 200℃, then perform segmented cooling. After the alloy liquid has completely solidified, remove the formed aluminum alloy ingot.

[0009] Optionally, the preparation of the Al-La rare earth master alloy specifically includes: Bulk rare earth element La is added to pure aluminum melt at a temperature of 725-745℃ and held for 20-30 minutes; the rare earth element La content accounts for 9-11% of the total weight. The melt was treated with high-energy ultrasound at a power of 400-800W for 20-30 minutes, and the ultrasonic power was maintained to continue heating the melt to 780-790℃ and hold for 8-10 minutes. Adjust the melt temperature to 720-730℃, refine and degas, remove slag, and then rapidly cool.

[0010] Optionally, the preparation of the Al-Ce rare earth master alloy includes: Pure aluminum is placed in a crucible and heated until it melts. When the temperature of the molten aluminum is 680-740℃, a block of rare earth Ce is wrapped in aluminum foil and pressed into the molten aluminum. The mixture is held at this temperature for 20-30 minutes to obtain an alloy liquid; wherein, rare earth Ce accounts for 12% of the total weight. The molten alloy is poured into a slurry preparation device and rotated at a speed of 60-120 r / min for 1-2 minutes. Finally, the molten alloy is taken out from the discharge port of the slurry preparation device, the slag is removed, and it is cast to obtain an Al-Ce rare earth master alloy.

[0011] Optionally, the segmented cooling includes: Cooling rate: 15-20℃ / min for 0-5 min; Cooling is carried out at a rate of 5-8℃ / min for 5-15 minutes, and then allowed to cool naturally until the temperature of the alloy melt drops below 300℃.

[0012] Optionally, before placing the 6061 aluminum alloy substrate in a melting furnace and heating it to 750°C for melting, the process further includes: Cut the 6061 aluminum alloy substrate into blocks and preheat it at 400-450℃ for 2 hours to remove surface oil.

[0013] Optionally, after obtaining the aluminum alloy ingot, the process further includes: sequentially performing solution treatment and aging treatment on the aluminum alloy ingot.

[0014] Optionally, the solution treatment includes: The aluminum alloy ingot is heated from room temperature to 500-550℃ at a rate of 5-8℃ / min, then held at that temperature for 1-3 hours, and then rapidly water-quenched after the holding period to obtain the solution-treated aluminum alloy ingot.

[0015] Optionally, the timeliness processing includes: The solution-treated aluminum alloy ingot is heated from room temperature to 160-200℃ at a rate of 3-5℃ / min, and then held at that temperature for 4-12 hours.

[0016] This invention discloses a rare-earth modified 6061 aluminum alloy material and its preparation method. By mass percentage, it comprises the following raw materials: 0.1-0.5% rare earth elements, 0.1-0.4% Al-Ti-B master alloy, 0.05-0.1% Al-Mg-Zr master alloy, with the balance being 6061 aluminum alloy substrate. The rare earth elements include La and / or Ce. By adding low-cost La and / or Ce light rare earths, Al-Ti-B master alloy, and Al-Mg-Zr master alloy, the grain size can be refined, the microstructure optimized, and the adverse effects of Fe impurity phases reduced. This improves the tensile strength and elongation of the material while reducing production costs, overcoming the limitations of high-priced rare earth applications, adapting to large-scale production, and meeting the needs of high-end fields. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a flowchart of a method for preparing a rare earth modified 6061 aluminum alloy material, which is optional according to an embodiment of the present invention. Figure 2 This is a metallographic comparison diagram of the pure 6061 aluminum alloy in Comparative Example 1 and the modified 6061 aluminum alloy obtained in Example 8. Detailed Implementation

[0018] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0019] This application provides a rare earth modified 6061 aluminum alloy material, which, by mass percentage, comprises the following raw materials: 0.1-0.5% rare earth elements, 0.1-0.4% Al-Ti-B master alloy, 0.05-0.1% Al-Mg-Zr master alloy, and the balance being 6061 aluminum alloy substrate. The rare earth elements include La and / or Ce.

[0020] Specifically, 6061 aluminum alloy is used as the base material. Its inherent composition of 0.8-1.2% Mg and 0.4-0.8% Si provides the alloy with good machinability and weldability. Simultaneously, it serves as a diffusion carrier for rare earth, Ti-B, and Mg-Zr modifying components, ensuring the stable performance of subsequent modification effects. The 0.1-0.5% rare earth elements La and / or Ce represent low-cost light rare earths. When the total rare earth element content is below 0.1%, it is difficult to fully form Al. l1 Ce2, A l1 Nanoscale reinforcing phases such as La3 have limited effect on improving the strength and corrosion resistance of alloys. Contents above 0.5% tend to aggregate at grain boundaries, forming coarse and brittle phases, which actually reduces toughness. A suitable content range can optimize the microstructure. Al-Ti-B master alloys with 0.1-0.4% content provide heterogeneous nucleation sites by releasing TiB2 particles, achieving grain refinement. Insufficient Al-Ti-B master alloy content results in a low number of TiB2 particles and poor grain refinement; excessive content leads to excess Ti reacting with the Si substrate to form coarse TiSi2 phases, damaging the matrix. This range can synergize with rare earth phases. To avoid element competition reactions and ensure grain refinement, 0.05-0.1% Al-Mg-Zr master alloy is used to replenish the Mg lost during the base material smelting. At the same time, Zr is introduced to form ZrFeSi phase with Fe and Si contained in the 6061 aluminum alloy base material to reduce harmful impurity phases and generate Al3Zr phase to assist in grain refinement. If the content is too low, the Mg replenishment will be insufficient and the Zr effect will be insignificant. If the content is too high, Zr will easily react with Ti and weaken the grain refinement effect. Overall, the functions of each component are complementary, and the mechanical properties of 6061 aluminum alloy are optimized and improved under the premise of low cost.

[0021] The rare earth modified 6061 aluminum alloy material in this application, by adding low-cost La and / or Ce light rare earths, Al-Ti-B master alloys and Al-Mg-Zr master alloys, can refine grains, optimize microstructure, and reduce the adverse effects of Fe impurity phases. While improving the mechanical properties of the material such as tensile strength and elongation, it significantly reduces production costs, breaks through the application limitations of high-priced rare earths, adapts to large-scale production, and meets the needs of high-end fields.

[0022] In one possible implementation, the mass ratio of Ce to La in the rare earth elements is (1-2):1; The mass percentage of rare earth elements in the Al-Ti-B master alloy is 2:(1-4).

[0023] Specifically, when rare earth elements include Ce and La, adding Ce and La in a mass ratio of (1-2):1 can more efficiently transform the coarse dendritic AlFeSi phase in 6061 aluminum alloy into rod-shaped and rare earth composite phases, reduce the adverse effects of impurities on performance, and synergistically improve the uniformity of the alloy's microstructure. Compared with the addition of a single rare earth element, it is more conducive to balancing the improvement of mechanical properties.

[0024] The mass ratio of Al-Ti-B master alloy to rare earth elements is 2:(1-4). Al-Ti-B provides a heterogeneous nucleation core to refine the grains, while rare earth elements optimize the distribution of precipitated phases, avoiding element waste or performance redundancy. This ensures the grain refinement effect while helping to steadily improve the mechanical properties of the alloy.

[0025] The Al-Mg-Zr master alloy not only replenishes the Mg lost through volatilization during the smelting of 6061 aluminum alloy, ensuring the formation of the Mg2Si basic strengthening phase, but also allows Zr to effectively react with Fe and Si to form fine ZrFeSi phases, reducing harmful impurity phases. Furthermore, it can form an Al3Zr phase to assist in grain refinement, thereby further optimizing the alloy's properties. The Al-Mg-Zr master alloy is prepared according to the following steps: Weigh out pure aluminum ingots, pure magnesium ingots, and Al-Zr master alloy with a Mg mass fraction of 3%~5%, a Zr mass fraction of 0.1%~0.3%, and the balance being industrial pure aluminum (purity ≥99.7%). Pure aluminum ingots are melted at 720~750℃ to form aluminum melt. When the temperature is raised to 740~760℃, pure magnesium ingots are added and stirred evenly. When the temperature is raised to 760~780℃, Al-Zr master alloy is added and stirring is continued to make the composition uniform. When the temperature of the melt obtained in the previous step is stable at 750~770℃, it is refined and degassed using argon or hexachloroethane, and then allowed to stand for 15~20 minutes to allow the inclusions to settle. After refining, the temperature is lowered to 710~730℃, and the melt is directly cast and cooled to solidify to obtain Al-Mg-Zr master alloy ingot.

[0026] like Figure 1 As shown, the present invention also provides a method for preparing rare earth modified 6061 aluminum alloy material, applicable to the rare earth modified 6061 aluminum alloy material described in the present invention, comprising: Step 1: Preparation of Al-La rare earth master alloy and preparation of Al-Ce rare earth master alloy; Step 2: Preheat the Al-La rare earth master alloy, Al-Ce rare earth master alloy, Al-Ti-B master alloy, and Al-Mg-Zr master alloy at 250-300℃ for 1 hour; Step 3: Place the 6061 aluminum alloy substrate in a melting furnace and heat it to 750℃ until it melts. Then add the preheated Al-La rare earth master alloy, Al-Ce rare earth master alloy and Al-Ti-B master alloy, and hold it at that temperature for 10 minutes. Then add the Al-Mg-Zr master alloy and refining agent in sequence. After refining, remove the slag. Step 4: After removing the slag, continue heating until the temperature of the alloy liquid stabilizes at 760-770℃. First, pour the alloy liquid into a metal mold preheated to 200℃, and then perform segmented cooling. After the alloy liquid has completely solidified, take out the formed aluminum alloy ingot.

[0027] Specifically, in step 1, pure La and Ce rare earth elements are highly reactive and easily oxidized and burned off when directly added to molten aluminum alloy. They are also difficult to disperse evenly, leading to unstable alloy composition. Preparing Al-La and Al-Ce rare earth master alloys can stably preserve La and Ce, reducing rare earth oxidation losses during subsequent smelting. This allows La and Ce to diffuse evenly into the aluminum matrix, laying the foundation for the formation of nanoscale reinforcing phases and ensuring stable modification effects.

[0028] Step 2: The surface of the intermediate alloy easily absorbs moisture and oil. Directly introducing it into the high-temperature molten aluminum will cause moisture to vaporize and create pores, and oil to decompose and contaminate the melt. It may also cause splashing due to the large temperature difference. Preheating the Al-La rare earth intermediate alloy, Al-Ce rare earth intermediate alloy, Al-Ti-B intermediate alloy, and Al-Mg-Zr intermediate alloy at 250-300℃ for 1 hour can remove moisture and oil, reduce the temperature difference with the molten aluminum, avoid splashing and gas introduction, and ensure stable melting and pure molten metal.

[0029] Step 3: First, heat the 6061 aluminum alloy substrate to 750℃ in a melting furnace until the substrate is completely melted. During heating, argon gas protection is activated. Preheated Al-La rare earth master alloy, Al-Ce rare earth master alloy, and Al-Ti-B master alloy are added and held at this temperature for 10 minutes to allow the three master alloys to fully melt and mix. During heating, electromagnetic induction in the induction coil of the melting furnace continuously stirs the molten aluminum alloy. Then, Al-Mg-Zr master alloy is added to replenish Mg. A refining agent is added to remove impurities and gases. After skimming off the slag, a pure melt is obtained. The refining agent is one of hexachloroethane (C2Cl6), magnesium chloride (MgCl2), or a mixed salt refining agent (such as a mixture of NaCl and KCl).

[0030] Step 4: After slag removal, the temperature is raised to 760-770℃, and then poured into a mold preheated to 200℃. Preheating the mold reduces thermal stress. The mold is then cooled in stages to allow the alloy liquid to solidify in an orderly manner and prevent abnormal grain growth. After complete solidification, the ingot is removed, completing the initial forming. The inner wall of the cast iron mold is coated with graphite emulsion.

[0031] The low-cost rare-earth modified 6061 aluminum alloy material and its preparation method disclosed in this application utilize low-cost, high-abundance La and / or Ce light rare-earth elements, combined with Al-Ti-B master alloys and Al-Mg-Zr master alloys of specific compositions. Through steps such as preheating, melting, refining, and segmented cooling, the alloy grains are effectively refined and the microstructure is optimized. The coarse dendritic AlFeSi phase in the substrate is transformed into rod-shaped and rare-earth composite phases, reducing the adverse effects of Fe impurity phases. This significantly improves the tensile strength and elongation of the alloy, while maintaining low production costs. It breaks through the application limitations of traditional reliance on high-cost rare earths such as Sc, and the process is suitable for large-scale production, meeting the performance and cost requirements of 6061 aluminum alloys in high-end fields such as aerospace and automotive manufacturing.

[0032] In one possible implementation, the preparation of the Al-La rare earth master alloy specifically includes: Bulk rare earth element La is added to pure aluminum melt at a temperature of 725-745℃ and held for 20-30 minutes; the rare earth element La content accounts for 9-11% of the total weight. The melt was treated with high-energy ultrasound at a power of 400-800W for 20-30 minutes, and the ultrasonic power was maintained to continue heating the melt to 780-790℃ and hold for 8-10 minutes. Adjust the melt temperature to 720-730℃, refine and degas, remove slag, and then rapidly cool.

[0033] Specifically, the raw materials are first melted and mixed. Block La and pure aluminum are weighed out in a ratio of 9-11% of the total weight of rare earth La. The pure aluminum is placed in a crucible and heated to 725-745℃ to completely melt it. Then, the block La is slowly added to the aluminum melt to avoid splashing due to violent reaction. The temperature is maintained in this range for 20-30 minutes. During this period, the melt is gently stirred with a graphite rod every 5-8 minutes to ensure that the La blocks are fully melted and evenly dispersed in the aluminum melt to form a preliminary mixed alloy melt.

[0034] Next, a high-energy ultrasonic probe with a power of 400-800W is inserted into the obtained alloy melt, and the ultrasonic equipment is started to continuously treat the melt for 20-30 minutes. During the process, the probe is kept stable to avoid touching the crucible wall. After the ultrasonic treatment is completed, the ultrasonic power is kept constant, and the temperature of the melt is raised to 780-790℃ through the heating device. This temperature is maintained for 8-10 minutes to further eliminate compositional segregation and refine the alloy structure by utilizing the synergistic effect of high temperature and ultrasound.

[0035] Then turn off the heating device and let the melt cool down naturally to 720-730℃. Add the refining agent hexachloroethane to the melt. The amount of hexachloroethane added is 0.3-0.5% of the total weight of the melt. Stir with a graphite rod for 1-2 minutes to promote the uniform distribution of the refining agent. After standing for 5 minutes, remove the surface slag with a slag skimmer. Quickly pour the refined pure melt into a water-cooled copper mold to achieve rapid cooling. After it is completely solidified, take it out to obtain the Al-La rare earth master alloy.

[0036] In one possible implementation, the preparation of the Al-Ce rare earth master alloy includes: Pure aluminum is placed in a crucible and heated until it melts. When the temperature of the molten aluminum is 680-740℃, a block of rare earth Ce is wrapped in aluminum foil and pressed into the molten aluminum. The mixture is held at this temperature for 20-30 minutes to obtain an alloy liquid; wherein, rare earth Ce accounts for 12% of the total weight. The molten alloy is poured into a slurry preparation device and rotated at a speed of 60-120 r / min for 1-2 minutes. Finally, the molten alloy is taken out from the discharge port of the slurry preparation device, the slag is removed, and it is cast to obtain an Al-Ce rare earth master alloy.

[0037] Specifically, first cut pure aluminum with a purity of ≥99.7% into small pieces, place them in a crucible and heat to 680-740℃ until they are completely melted; weigh out blocks of Ce according to a ratio of 12% of the total weight of rare earth Ce, wrap them tightly with 2-3 layers of aluminum foil, and then use a graphite rod to press them vertically into the middle of the aluminum liquid (to a depth of about 2 / 3 of the height of the aluminum liquid) to prevent them from floating and coming into contact with air; then keep them at this temperature range for 20-30 minutes, during which time the aluminum liquid is gently stirred with a graphite rod 1-2 times every 5-10 minutes to promote uniform melting and diffusion of Ce and reduce oxidation loss.

[0038] Preheat the slurry preparation equipment to 150-200℃ and check the equipment to ensure that the spiral blades rotate smoothly and the discharge port is unobstructed. Pour the heat-preserved alloy liquid into the equipment inlet at a flow rate of 5-10L / min along the guide channel. Start the equipment and rotate the spiral blades at a speed of 60-120r / min for 1-2 minutes to break up coarse compounds and homogenize the composition through shearing action. After processing, open the discharge port, remove the surface slag with a graphite spoon, and quickly pour the pure alloy liquid into a metal mold preheated to 200℃ and coated with a release agent. After cooling to room temperature, demold to obtain the Al-Ce rare earth master alloy.

[0039] In one possible implementation, the segmented cooling includes: Cooling rate: 15-20℃ / min for 0-5 min; Cooling is carried out at a rate of 5-8℃ / min for 5-15 minutes, and then allowed to cool naturally until the temperature of the alloy melt drops below 300℃.

[0040] Specifically, the refined molten alloy is poured smoothly into a preheated copper mold (metal mold) at 200°C. The mold is immediately placed on a temperature-controlled cooling platform, the cooling system is started, and initial parameters are set, with the cooling water flow rate adjusted to 15-20 L / min. Throughout the process, the temperature is monitored in real-time via thermocouples built into the mold, with data recorded every 30 seconds. This ensures that the cooling rate remains stable at 15-20°C / min for the first 5 minutes, preventing uneven cooling of the mold and alloy components due to unstable cooling rates, which could generate thermal stress and lead to mold deformation or cracking of the alloy surface.

[0041] At the 5-minute mark, reduce the flow rate to 5-8 L / min in water-cooling mode, and continue monitoring the temperature, recording it every minute to ensure the cooling rate is controlled at 5-8℃ / min for 10 minutes. Slowing down the cooling rate releases internal stress in the alloy and prevents cracking of the ingot. At the 15-minute mark, turn off the active cooling system and move the mold from the cooling platform to a workbench lined with insulating cotton, allowing it to dissipate heat naturally at room temperature. Check the ingot surface temperature with an infrared thermometer every 30 minutes. After 1.5-3 hours, when the mold temperature drops below 300℃ and complete solidification is confirmed, the ingot can be demolded, yielding an alloy ingot with a uniform internal structure and low stress.

[0042] In one possible implementation, the process further includes: […]. Cut the 6061 aluminum alloy substrate into blocks and preheat it at 400-450℃ for 2 hours to remove surface oil.

[0043] Specifically, before feeding the 6061 aluminum alloy substrate into the melting furnace, use a metal cutter to cut it into blocks with sides of 5-10cm, according to the capacity of the furnace crucible and the required feed size (avoiding blocks that are too large, which will cause slow melting, and blocks that are too small, which will cause splashing during melting). Protective glasses and gloves must be worn during the cutting process to prevent cuts from metal shavings. After cutting, place the blocks into a hot air circulating preheating furnace. First, close the furnace door and check the furnace's sealing to ensure temperature stability. Then, set the preheating temperature to 40°C. Start the preheating program at 0-450℃ for 2 hours. During preheating, check the substrate condition through the furnace observation window every 30 minutes to avoid local overheating that could cause oxidation of the substrate surface. After 2 hours of preheating, open the furnace door and use a long-handled clamp to remove the substrate block. At this point, the oil stains adsorbed on the substrate surface (such as cutting oil or rust-preventive oil left over from storage or cutting) have completely evaporated at high temperature (some oil stains will be converted into harmless gases and discharged with the furnace ventilation). Quickly wipe the substrate surface with a clean cloth to remove any slight residual oxidation dust.

[0044] In one possible implementation, after obtaining the aluminum alloy ingot, the process further includes: sequentially subjecting the aluminum alloy ingot to solution treatment and aging treatment.

[0045] Specifically, solution treatment involves heating an aluminum alloy ingot to a suitable temperature and holding it at that temperature for a period of time. This allows the strengthening phases that are originally present in the ingot to fully dissolve into the aluminum matrix, forming a supersaturated solid solution. Then, rapid cooling (such as water quenching) is used to "fix" the solute atoms in the matrix, preventing them from precipitating prematurely during cooling. This eliminates the uneven composition inside the ingot and the internal stress generated during solidification, improving the plasticity and toughness of the alloy. At the same time, it prepares solute atoms that can participate in strengthening for subsequent aging treatment.

[0046] Aging treatment involves placing a solution-treated aluminum alloy ingot at a low temperature for an extended period, allowing the supersaturated solute atoms in the solid solution to slowly precipitate as fine, uniform nanoscale second phases (reinforcing phases). These precipitated phases hinder the movement of dislocations in the aluminum matrix, further enhancing the alloy's hardness and strength, ultimately enabling the aluminum alloy to achieve the mechanical properties required for its application, fully leveraging the performance-enhancing effect of rare earth modification.

[0047] In one possible implementation, the solution treatment includes: The aluminum alloy ingot is heated from room temperature to 500-550℃ at a rate of 5-8℃ / min, then held at that temperature for 1-3 hours, and then rapidly water-quenched after the holding period to obtain the solution-treated aluminum alloy ingot.

[0048] Specifically, during solution treatment, the aluminum alloy ingot is first fixed with a high-temperature resistant clamp and placed stably into a box-type heat treatment furnace, ensuring a 5-10cm gap between the ingots to guarantee uniform heating. Then, the furnace door is closed and the heating program is started, setting the temperature to rise from room temperature at a rate of 5-8℃ / min. During the process, the temperature is monitored in real time through thermocouples inside the furnace, and data is recorded every 10 minutes to avoid excessive heating that could cause cracks in the ingot due to thermal stress. When the furnace temperature reaches 500-550℃, the furnace is switched to a heat preservation mode and maintained for 1-3 hours. During the heat preservation period, the ingot status is checked every 30 minutes through the furnace observation window to prevent local overheating or excessive surface oxidation. After the heat preservation is completed, the furnace door is immediately opened, and the ingot is quickly removed using a long-handled high-temperature resistant tool and placed into a pre-prepared room-temperature water tank. The water volume in the tank should be at least 5 times the volume of the ingot, ensuring that the ingot is completely submerged in water to guarantee a stable cooling effect. After the ingot is cooled to room temperature in water, it is taken out and the surface residual moisture is dried with compressed air, thus completing the solution treatment and obtaining the solution-treated aluminum alloy ingot.

[0049] In one possible implementation, the time-sensitive processing includes: The solution-treated aluminum alloy ingot is heated from room temperature to 160-200℃ at a rate of 3-5℃ / min, and then held at that temperature for 4-12 hours.

[0050] Specifically, during the aging process, the surface of the aluminum alloy ingot, which has been cooled to room temperature after solution treatment, is first wiped clean to remove residual moisture and slight oxide scale. Then, the ingot is placed in an aging furnace, and the furnace door is closed to check the furnace's airtightness to prevent temperature fluctuations. The heating program is then started, with a slow heating rate of 3-5℃ / min starting from room temperature. During this process, the temperature is monitored in real time using multiple thermocouples inside the furnace, and data is recorded every 15 minutes to avoid stress concentration inside the ingot due to excessively rapid heating. Once the furnace temperature stabilizes at 160-200℃, the process is switched to a holding mode and maintained for 4-12 hours. During the holding period, the furnace temperature gauge is checked regularly to ensure that the temperature deviation is controlled within ±5℃. At the same time, frequent opening of the furnace door is avoided to prevent sudden drops in furnace temperature from affecting the aging effect. After the holding period, the heating system is first turned off, and the ingot is allowed to cool down to below 200℃ with the furnace. Then, the furnace door is opened to allow it to cool naturally to room temperature, ultimately yielding an age-strengthened aluminum alloy ingot with stable mechanical properties.

[0051] The present application will be further illustrated by the following embodiments. Example

[0052] The ingredients were weighed and mixed according to the following proportions: 0.2% by mass of rare earth element La, 0.2% by mass of Al-Ti-B master alloy, 0.05% by mass of Al-Mg-Zr master alloy, and the balance being pure 6061 aluminum alloy substrate.

[0053] Pure 6061 aluminum alloy substrate was cut into 8cm×8cm×5cm blocks. After removing the surface oxide scale, it was placed in a hot air circulating preheating furnace and held at 430℃ for 2 hours. During this period, it was checked every 30 minutes to prevent overheating and oxidation. After removal, the surface dust and oil stains were wiped off with a dust-free cotton cloth. The pre-prepared Al-La master alloy and Al-Ce master alloy were cut into 2cm×2cm small pieces and placed in the preheating furnace together with the Al-Ti-B master alloy and Al-Mg-Zr master alloy. It was held at 270℃ for 1 hour and turned over every 20 minutes to remove moisture and oil stains. After cooling, it was sealed and temporarily stored to prevent moisture absorption.

[0054] Turn on the medium-frequency induction melting furnace, add the preheated 6061 substrate, turn on the argon protection, raise the temperature to 750℃, and after confirming that the substrate is completely melted and there are no unmelted particles, maintain the temperature stable.

[0055] First, add the preheated Al-La, Al-Ce, and Al-Ti-B master alloys to molten aluminum at 750°C, and then use an induction coil for electromagnetic stirring. After holding at 750°C for 10 minutes, add the Al-Mg-Zr master alloy and stir for 3 minutes. If the temperature is below 740°C, raise the temperature to 750°C.

[0056] Add hexachloroethane refining agent in three portions, each at 0.4% of the total weight of the melt, with a 2-minute interval between each addition. Press the agent into the melt with a graphite rod. After reacting for 8 minutes, remove the scum along the crucible wall. Finally, stir for 1 minute to ensure uniform composition.

[0057] The inner wall of the cast iron mold is coated with graphite emulsion and preheated to 200℃ for 30 minutes. The alloy liquid is then heated to 760-770℃ and allowed to stand for 5 minutes to eliminate disturbance. The alloy liquid is then injected into the mold along a 30° inclined guide channel. For the first 0-5 minutes, the mold is placed on a water-cooled cooling table with a cooling water flow rate of 18L / min and a cooling rate of 18℃ / min. For the next 5-15 minutes, the flow rate is adjusted to 7L / min and the cooling rate is 6℃ / min (the final temperature after 15 minutes is 615℃). After 15 minutes, the water cooling is turned off, and the mold is moved to an insulated cotton worktable for natural cooling. Once the temperature drops below 300℃, the mold is demolded to obtain a rare earth modified 6061 aluminum alloy ingot. Example

[0058] The mixture was prepared by adding a single rare earth element, specifically: 0.2% Ce (by mass), 0.2% Al-Ti-B master alloy, 0.05% Al-Mg-Zr master alloy, with the balance being 6061 aluminum alloy substrate. The ingredients were weighed and mixed. Subsequent steps were the same as in Example 1. Example

[0059] The rare earth elements La and Ce were mixed in a 1:1 mass ratio, i.e., La was 0.1% by mass, Ce was 0.1% by mass, Al-Ti-B master alloy was 0.2% by mass, Al-Mg-Zr master alloy was 0.05% by mass, and the balance was 6061 aluminum alloy substrate. The materials were weighed and mixed. Subsequent operating steps were the same as in Example 1. Example

[0060] The rare earth elements La and Ce were mixed in a 1:2 mass percentage ratio, i.e., La was 0.1% by mass, Ce was 0.2% by mass, Al-Ti-B master alloy was 0.2% by mass, Al-Mg-Zr master alloy was 0.05% by mass, and the balance was 6061 aluminum alloy substrate. The materials were weighed and mixed. Subsequent operating steps were the same as in Example 1. Example

[0061] The rare earth elements La and Ce were mixed in a 1:2 mass ratio, i.e., La accounted for 0.1% of the mass, Ce accounted for 0.2% of the mass, Al-Ti-B master alloy accounted for 0.4% of the mass, and the balance was 6061 aluminum alloy substrate. The materials were weighed and mixed. The subsequent operating steps were the same as in Example 1. Example

[0062] The rare earth elements La and Ce were mixed in a 1:1 mass ratio, i.e., La was 0.2% by mass, Ce was 0.2% by mass, Al-Ti-B master alloy was 0.2% by mass, Al-Mg-Zr master alloy was 0.05% by mass, and the balance was 6061 aluminum alloy substrate. The materials were weighed and mixed. The subsequent operating steps were the same as in Example 1. Example

[0063] The rare earth elements La and Ce were mixed in a 1:1 mass ratio, with La accounting for 0.1% and Ce for 0.1% of the total mass. The Al-Ti-B master alloy accounted for 0.2% of the total mass, and the Al-Mg-Zr master alloy accounted for 0.05% of the total mass. The balance was pure 6061 aluminum alloy substrate. The materials were weighed and mixed.

[0064] Pure 6061 aluminum alloy substrate was cut into 8cm×8cm×5cm blocks. After removing the surface oxide scale, it was placed in a hot air circulating preheating furnace and held at 430℃ for 2 hours. During this period, it was checked every 30 minutes to prevent overheating and oxidation. After removal, the surface dust and oil stains were wiped off with a dust-free cotton cloth. The pre-prepared Al-La master alloy and Al-Ce master alloy were cut into 2cm×2cm small pieces and placed in the preheating furnace together with the Al-Ti-B master alloy and Al-Mg-Zr master alloy. It was held at 270℃ for 1 hour and turned over every 20 minutes to remove moisture and oil stains. After cooling, it was sealed and temporarily stored to prevent moisture absorption.

[0065] Turn on the medium-frequency induction melting furnace, add the preheated 6061 substrate, turn on the argon protection, raise the temperature to 750℃, and after confirming that the substrate is completely melted and there are no unmelted particles, maintain the temperature stable.

[0066] First, add the preheated Al-La, Al-Ce, and Al-Ti-B master alloys to molten aluminum at 750°C, and then use an induction coil for electromagnetic stirring. After holding at 750°C for 10 minutes, add the Al-Mg-Zr master alloy and stir for 3 minutes. If the temperature is below 740°C, raise the temperature to 750°C.

[0067] Add hexachloroethane refining agent in three portions, each at 0.4% of the total weight of the melt, with a 2-minute interval between each addition. Press the agent into the melt with a graphite rod. After reacting for 8 minutes, remove the scum along the crucible wall. Finally, stir for 1 minute to ensure uniform composition.

[0068] The inner wall of the cast iron mold is coated with graphite emulsion and preheated to 200℃ for 30 minutes. The alloy liquid is then heated to 760-770℃ and allowed to stand for 5 minutes to eliminate disturbance. The alloy liquid is then injected into the mold along a 30° inclined guide channel. For the first 0-5 minutes, the mold is placed on a water-cooled cooling table with a cooling water flow rate of 18L / min and a cooling rate of 18℃ / min. For the next 5-15 minutes, the flow rate is adjusted to 7L / min and the cooling rate is 6℃ / min (the final temperature after 15 minutes is 615℃). After 15 minutes, the water cooling is turned off, and the mold is moved to an insulated cotton worktable for natural cooling. Once the temperature drops below 300℃, the mold is demolded to obtain a rare earth modified 6061 aluminum alloy ingot.

[0069] Fix the ingots in a box furnace with a clamp, leaving a 5-10cm gap between the ingots. Heat the furnace from room temperature to 530℃ at a rate of 6℃ / min and hold for 2 hours. Check for overheating every 30 minutes. After holding, quickly remove the ingots and place them in a water bath of 5 times their volume at room temperature for water quenching. After cooling to room temperature, blow dry the ingots.

[0070] After wiping the surface of the ingot after solution treatment, place it in an aging furnace. After sealing the furnace, raise the temperature to 180℃ at a rate of 4℃ / min and hold for 8 hours (temperature deviation ±5℃). After the aging furnace is closed, turn off the heating and let it cool to below 200℃ with the furnace, and then let it cool naturally to room temperature. Example

[0071] The rare earth elements La and Ce were mixed in a 1:2 mass ratio, i.e., La accounted for 0.1% of the mass, Ce accounted for 0.2% of the mass, Al-Ti-B master alloy accounted for 0.2% of the mass, and Al-Mg-Zr master alloy accounted for 0.05% of the mass. The materials were weighed and mixed. Subsequent operating steps were the same as in Example 7.

[0072] Comparative Example 1 The pure 6061 aluminum alloy without the addition of any rare earth elements and grain refiners was smelted using the same steps as in Example 1.

[0073] Comparative Example 2 The rare earth elements La and Ce were mixed in a 1:2 mass ratio, i.e., La accounted for 0.1% and Ce accounted for 0.2% by mass. The materials were weighed and mixed without adding Al-Ti-B or Al-Mg-Zr master alloys. Subsequent operating procedures were the same as in Example 1.

[0074] Comparative Example 3 The raw materials were weighed and batched according to 0.2% by mass of Al-Ti-B master alloy, without adding rare earth elements or Al-Mg-Zr master alloy. Subsequent operating procedures were the same as in Example 1.

[0075] Comparative Example 4 The rare earth elements La and Ce were mixed in a 1:1 mass ratio, i.e., La accounted for 0.1% of the mass, Ce accounted for 0.1% of the mass, and the Al-Ti-B master alloy accounted for 0.2% of the mass. No Al-Mg-Zr master alloy was added, and the balance was pure 6061 aluminum alloy substrate. The materials were weighed and mixed. The subsequent operating steps were the same as in Example 7.

[0076] Comparative Example 5 The rare earth elements La and Ce were mixed in a 1:1 mass ratio, i.e., 0.1% La and 0.1% Ce. No Al-Ti-B master alloy was added, but 0.05% Al-Mg-Zr master alloy was added, with the balance being pure 6061 aluminum alloy substrate. The materials were weighed and mixed. Subsequent operating steps were the same as in Example 7.

[0077] Tensile tests were performed on all alloys prepared in the examples and comparative examples. The test specimens were processed strictly according to the specimen proportions in the national standard GB / T228.1-2021. The raw material ratios and mechanical properties of each example and comparative example are compared in Table 1. Table 1 Comparison of alloy proportions and mechanical properties in each embodiment and comparative example

[0078] Table 1 shows that the addition of La and Ce rare earth elements in different proportions, either individually or in combination with Al-Ti-B and Al-Mg-Zr master alloys, all positively affect the mechanical properties of 6061 aluminum alloy. However, the optimal mechanical properties of 6061 aluminum alloy (195.7 MPa) are achieved when the La:Ce ratio is 1:2 and the Al-Ti-B master alloy content is 0.2%. After heat treatment, its tensile strength increases to 351 MPa. Furthermore, the simultaneous addition of Al-Ti-B and Al-Mg-Zr master alloys can further improve the mechanical properties of the prepared 6061 aluminum alloy.

[0079] Figure 2 In the figure, the left side is the metallographic image of the 6061 aluminum alloy in Example 1, and the right side is the metallographic image of the rare earth modified 6061 aluminum alloy prepared in Example 8. Figure 2 It can be seen that the grain size of rare earth modified 6061 aluminum alloy is significantly smaller than that of 6061 aluminum alloy, indicating that the modification method of this scheme can refine the grain size of 6061 aluminum alloy.

[0080] In summary, this invention innovatively utilizes the synergistic effect of relatively inexpensive rare earth elements with Al-Ti-B and Al-Mg-Zr master alloys to effectively refine the grain size of 6061 aluminum alloy. This results in a simultaneous improvement in the uniformity of the material's microstructure and its mechanical properties. While ensuring improved material performance, it significantly reduces production costs. This not only meets the application requirements of high-end fields but also successfully overcomes the application limitations caused by the excessively high cost of traditional aluminum alloy modification using expensive rare earth elements such as Sc. Thus, it achieves the modification of traditional 6061 aluminum alloy materials.

[0081] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A rare earth-modified 6061 aluminum alloy material, characterized in that, The raw materials comprise, by weight percentage: 0.1-0.5% rare earth elements, 0.1-0.4% Al-Ti-B master alloy, 0.05-0.1% Al-Mg-Zr master alloy, with the balance being 6061 aluminum alloy substrate, wherein the rare earth elements include La and / or Ce.

2. The rare earth modified 6061 aluminum alloy material according to claim 1, characterized in that, The mass ratio of Ce to La in the rare earth elements is (1-2):1; The mass percentage of rare earth elements in the Al-Ti-B master alloy is 2:(1-4).

3. A method for preparing a rare earth-modified 6061 aluminum alloy material, characterized in that, Applied to the rare earth modified 6061 aluminum alloy material according to any one of claims 1 and 2, comprising: Preparation of Al-La rare earth master alloys and preparation of Al-Ce rare earth master alloys; The Al-La rare earth master alloy, Al-Ce rare earth master alloy, Al-Ti-B master alloy, and Al-Mg-Zr master alloy were preheated at 250-300℃ for 1 hour. After the 6061 aluminum alloy substrate is placed in a melting furnace and heated to 750℃ to melt, preheated Al-La rare earth master alloy, Al-Ce rare earth master alloy and Al-Ti-B master alloy are added, and then the temperature is held for 10 minutes. Then Al-Mg-Zr master alloy and refining agent are added in sequence. After refining, the slag is removed. After removing the slag, continue heating until the alloy liquid temperature stabilizes at 760-770℃. First, pour the alloy liquid into a metal mold preheated to 200℃, then perform segmented cooling. After the alloy liquid has completely solidified, remove the formed aluminum alloy ingot.

4. The method for preparing rare earth modified 6061 aluminum alloy material according to claim 3, characterized in that, The preparation of the Al-La rare earth master alloy specifically includes: Bulk rare earth element La is added to pure aluminum melt at a temperature of 725-745℃ and held for 20-30 minutes; the rare earth element La content accounts for 9-11% of the total weight. The melt was treated with high-energy ultrasound at a power of 400-800W for 20-30 minutes, and the ultrasonic power was maintained to continue heating the melt to 780-790℃ and hold for 8-10 minutes. Adjust the melt temperature to 720-730℃, refine and degas, remove slag, and then rapidly cool.

5. The method for preparing rare earth modified 6061 aluminum alloy material according to claim 3, characterized in that, The preparation of the Al-Ce rare earth master alloy includes: Pure aluminum is placed in a crucible and heated until it melts. When the temperature of the molten aluminum is 680-740℃, a block of rare earth Ce is wrapped in aluminum foil and pressed into the molten aluminum. The mixture is held at this temperature for 20-30 minutes to obtain an alloy liquid; wherein, rare earth Ce accounts for 12% of the total weight. The molten alloy is poured into a slurry preparation device and rotated at a speed of 60-120 r / min for 1-2 minutes. Finally, the molten alloy is taken out from the discharge port of the slurry preparation device, the slag is removed, and it is cast to obtain an Al-Ce rare earth master alloy.

6. The method for preparing rare earth modified 6061 aluminum alloy material according to claim 3, characterized in that, The segmented cooling includes: Cooling rate: 15-20℃ / min for 0-5 min; Cooling is carried out at a rate of 5-8℃ / min for 5-15 minutes, and then allowed to cool naturally until the temperature of the alloy melt drops below 300℃.

7. The method for preparing rare earth modified 6061 aluminum alloy material according to claim 3, characterized in that, Before placing the 6061 aluminum alloy substrate in a melting furnace and heating it to 750°C to melt it, the following steps are also included: Cut the 6061 aluminum alloy substrate into blocks and preheat it at 400-450℃ for 2 hours to remove surface oil.

8. The method for preparing rare earth modified 6061 aluminum alloy material according to claim 3, characterized in that, After obtaining the aluminum alloy ingot, the process also includes: sequentially performing solution treatment and aging treatment on the aluminum alloy ingot.

9. The method for preparing rare earth modified 6061 aluminum alloy material according to claim 8, characterized in that, The solution treatment includes: The aluminum alloy ingot is heated from room temperature to 500-550℃ at a rate of 5-8℃ / min, then held at that temperature for 1-3 hours, and then rapidly water-quenched after the holding period to obtain the solution-treated aluminum alloy ingot.

10. The method for preparing rare earth modified 6061 aluminum alloy material according to claim 9, characterized in that, The timeliness processing includes: The solution-treated aluminum alloy ingot is heated from room temperature to 160-200℃ at a rate of 3-5℃ / min, and then held at that temperature for 4-12 hours.

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