High-strength wear-resistant recycled cast aluminum alloy and preparation method thereof

Abstract

The application relates to a high-strength wear-resistant recycled cast aluminum alloy and a preparation method thereof. The high-strength wear-resistant recycled cast aluminum alloy comprises the following components in percentage by mass: Si: 6.0-8.5%, Mg: 0.5-1.2%, Cu: 1.0-1.8%, Zn: 1.5-3.0%, Mn: 0.6-1.2%, Zr: 0.15-0.40%, Ti: 0.10-0.30%, Fe: 0.20-0.80%, nano composite particles: 0.5-1.5%, rare earth elements: 0.3-0.8%, and the balance of Al and inevitable impurities; wherein the mass ratio of Mn to Fe is (0.8-1.5):1, the nano composite particles are a mixture of nano TiC and nano SiC and the mass ratio is (2-6):1, and the rare earth elements include La and Ce and the mass ratio is 1:1 to 3:1. The harmful needle-shaped iron-rich phase in the recycled aluminum is converted into a granular strengthening phase by Mn / Fe ratio regulation, combined with nano TiC and SiC dual-phase synergistic strengthening and La / Ce rare earth modification treatment, and combined with a graded solid solution and double-stage aging process, so that the recycled cast aluminum alloy has high strength, high wear resistance and excellent high-temperature stability, and the high-value utilization of the recycled aluminum is realized.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloys, specifically to a high-strength, wear-resistant, regenerated cast aluminum alloy and its preparation method. Background Technology

[0002] With the advancement of the circular economy and the "dual-carbon" strategy, the market share of recycled aluminum alloys has been increasing year by year. However, due to the complex source of raw materials, recycled aluminum inevitably contains a high proportion of impurity elements such as Fe and Zn. Among them, Fe easily forms coarse needle-like β-Al5FeSi phases during the casting solidification process, which severely damages the matrix, reduces plasticity and wear resistance, and thus recycled aluminum alloys can usually only be used for low-end castings, making it difficult to meet the needs of the automotive, machinery and other industries for high-performance structural parts.

[0003] Existing technologies for improving the strength and wear resistance of cast aluminum alloys typically employ methods such as adding alloying elements, modification treatment, or introducing nano-reinforcing phases. For example, patent CN120099358B improves wear resistance by adding nano-TiC particles; patent CN105838947B improves alloy strength through rare earth elements. However, existing technologies are mostly designed for virgin pure aluminum and do not fully consider the special characteristics of high Fe impurities in recycled aluminum. Furthermore, the reinforcing phases are mostly single nanoparticles, which have poor dispersibility and are prone to agglomeration in molten aluminum. In addition, some technologies employ processes such as ultrasonic dispersion, which are difficult to apply in large-scale industrial smelting.

[0004] Therefore, developing a cast aluminum alloy that is systematically reverse-engineered based on the characteristics of impurities in recycled aluminum, possesses both high strength and high wear resistance, and whose process is suitable for industrial mass production has significant application value. Summary of the Invention

[0005] To address the problems existing in the prior art, the purpose of this invention is to provide a high-strength, wear-resistant, regenerated cast aluminum alloy and its preparation method.

[0006] The objective of this invention is achieved through the following technical solution: In a first aspect, the present invention provides a high-strength, wear-resistant, recycled cast aluminum alloy, comprising the following components by mass percentage: Si: 6.0-8.5%; Mg: 0.5-1.2%; Cu: 1.0-1.8%; Zn: 1.5-3.0%; Mn: 0.6-1.2%; Zr: 0.15-0.40%; Ti: 0.10-0.30%; Fe: 0.20-0.80%; Nanocomposite particles: 0.5-1.5%; Rare earth elements: 0.3-0.8%; Balance: Al and unavoidable impurities.

[0007] Preferably, the mass ratio of Mn to Fe is (0.8-1.5):1.

[0008] Preferably, the nanocomposite particles are a mixture of nano-TiC and nano-SiC, with a mass ratio of nano-TiC to nano-SiC of (2-6):1.

[0009] Preferably, the rare earth elements include La and Ce, wherein the mass ratio of La to Ce is 1:1 to 3:1.

[0010] Preferably, the particle size of the nanocomposite particles is 20-70 nm.

[0011] Secondly, the present invention provides a method for preparing the above-mentioned high-strength, wear-resistant, recycled cast aluminum alloy, comprising the following steps: S1: Nano TiC particles and nano SiC particles are mixed in anhydrous ethanol at a mass ratio, surfactant is added, and the mixture is pretreated by high-energy ball milling to obtain a slurry. The slurry is vacuum dried under heating conditions to obtain a composite powder. The composite powder is then mixed with aluminum powder and pressed into a block-shaped preform. S2: Weigh recycled aluminum ingots and master alloys of Al-20Si, Al-50Cu, Al-10Mg, Al-30Zn, Al-10Mn, Al-10Zr, Al-5Ti, Al-La and Al-Ce according to the composition mass ratio, and melt them under a protective atmosphere. After melting, the melt is cooled, and the nanocomposite particle preforms prepared in S1 are added and stirred. S3: Add refining agent to the melt obtained in S2 for refining and degassing. After refining, let it stand for 15-25 minutes, preheat the mold, and use the extrusion casting process to pour the refined melt into a casting. S4: Place the casting obtained in S3 in a heat treatment furnace and perform staged solution treatment: first raise the furnace temperature to 500℃ and hold for 2-3 hours, then raise the temperature to 520℃-525℃ and hold for 2-4 hours. After solution treatment, quickly quench the casting in water at 60℃-80℃, with a transfer time not exceeding 15 seconds. S5: Perform a two-stage aging treatment on the quenched casting obtained in S4: First, heat the casting to 120℃-140℃ at a rate of 2℃-5℃ / min and hold for 4-8 hours. After holding, introduce air to cool the casting to room temperature. Then, heat the casting to 165℃-185℃ at a rate of 2℃-5℃ / min and hold for 3-6 hours. After completion, introduce air to cool the casting to room temperature to obtain the final product.

[0012] Preferably, in step S1, the surfactant is polyvinylpyrrolidone, and the amount added is 3%-6% of the total mass of the nanoparticles; the pretreatment ball-to-particle ratio is (8-12):1, the ball milling time is 2-4 hours, and the ball milling speed is 300-500 rpm; the vacuum drying temperature is 60℃-80℃, and the time is 6-12 hours; the composite powder and aluminum powder are mixed at a mass ratio of 1:(1-3) and pressed into preforms under a pressure of 200-300 MPa; the monomer mass of the preform is 50-200 g.

[0013] Preferably, in step S2, the protective atmosphere is argon, and the gas flow rate is 5-15 L / min; the melting process specifically involves: melting aluminum ingots and heating them to 730℃-760℃, adding intermediate alloys for rare earth modification treatment, and holding at that temperature for 15-20 min; before adding the nanocomposite particle preform, cooling the melt to 710℃-730℃; the stirring process specifically involves: using a rotary electromagnetic stirring device with a stirring frequency of 50-100 Hz, a stirring intensity of 0.5-1.5 T, and a stirring time of 10-20 min, so that the nanoparticles are uniformly dispersed in the melt.

[0014] Preferably, in step S3, the refining agent is a mixture of hexachloroethane and sodium chloride, and the amount added is 0.3% to 0.8% of the melt mass; the refining temperature is 710℃-730℃, the refining time is 10-20 min; and the mold preheating temperature is 200℃-300℃.

[0015] Preferably, in step S4, the heating rate of the solution treatment is 5℃-10℃ / min, and the solution temperature is 10℃-15℃ lower than the initial melting point of the alloy; the initial melting point of the alloy is determined in advance by differential scanning calorimetry.

[0016] The beneficial effects of this invention are as follows: 1. This invention addresses the high Fe content in recycled aluminum by controlling the mass ratio of Mn to Fe, transforming the harmful coarse needle-like β-Al5FeSi phase into fine granular or short rod-shaped α-Al(Mn,Fe)Si phase. This significantly reduces the adverse effects of Fe on plasticity and wear resistance, enabling recycled aluminum to be used in high-performance structural components.

[0017] 2. This invention uses nano-TiC and nano-SiC dual-phase composite reinforcement. When the two are combined, they produce a significant synergistic effect: TiC alone provides hard anti-wear support, while SiC alone improves interfacial bonding and forms a transfer lubricating film containing Si and C during friction. The reinforcement network formed by the two together reduces the wear rate by about 21% compared to TiC reinforcement alone, and by about 33% compared to SiC reinforcement alone. Compared to ordinary ADC12 recycled aluminum alloy, the wear resistance is improved by about 55%.

[0018] 3. Rare earth elements La and Ce can refine eutectic silicon to improve its plasticity. At the same time, they can agglomerate at the interface between nanoparticles and aluminum matrix, reduce interfacial energy and improve bonding strength, or work together with Zr and Ti to form a highly thermally stable dispersed phase, effectively pinning grain boundaries and inhibiting grain boundary migration and coarsening of strengthening phases at high temperatures.

[0019] 4. This invention uses a specific preparation process to encapsulate and isolate nanoparticles in the preform with aluminum powder, which is then gradually released after being added to the melt. Combined with a rotating electromagnetic stirrer to generate forced convection of the entire melt, this invention achieves uniform dispersion of nanoparticles in furnaces ranging from kilograms to tons. The process is mature and reliable and suitable for industrial-scale production.

[0020] 5. The recycled cast aluminum alloy prepared by this invention has a tensile strength that is increased by more than 50% and a wear resistance that is increased by about 45% to 55% compared with ordinary ADC12 recycled aluminum alloy. Its comprehensive performance is significantly better than that of conventional recycled aluminum alloy, realizing the high-value utilization of recycled aluminum. Detailed Implementation

[0021] The technical solution of the present invention is illustrated below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or defining the scope of the present invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the present invention.

[0022] To better understand the above technical solutions, exemplary embodiments of the present invention are described in more detail below. While exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the invention to those skilled in the art.

[0023] The present invention will be further described below with reference to the following embodiments. Example 1

[0024] A high-strength, wear-resistant, recycled cast aluminum alloy, comprising the following components by weight percentage: Si: 7.2%, Mg: 0.9%, Cu: 1.5%, Zn: 2.5%, Mn: 0.8%, Zr: 0.25%, Ti: 0.20%, Fe: 0.55%, nano TiC particles: 0.80%, nano SiC particles: 0.20%, La: 0.40%, Ce: 0.15%, with the balance being Al and unavoidable impurities.

[0025] The mass ratio of Mn to Fe is 1.45:1, the mass ratio of nano-TiC to nano-SiC is 4:1, the mass ratio of La to Ce is 2.67:1, and the particle size of the nanocomposite particles is 40 nm.

[0026] The preparation method of the above-mentioned high-strength, wear-resistant, recycled cast aluminum alloy includes the following steps: S1: Nano-TiC particles and nano-SiC particles were mixed at a mass ratio of 4:1 and dispersed in anhydrous ethanol. Polyvinylpyrrolidone (PVP) accounting for 5% of the total mass of nanoparticles was added as a surfactant. The mixture was pretreated by high-energy ball milling with a ball-to-particle ratio of 10:1, a milling time of 3 hours, and a milling speed of 400 rpm to obtain a slurry. The slurry was vacuum dried at 70°C for 9 hours to obtain a composite powder. The composite powder was then mixed with aluminum powder at a mass ratio of 1:2 and pressed into a block-shaped preform under a pressure of 250 MPa. The monomer mass of the preform was 100 g. S2: Weigh recycled aluminum ingots and master alloys of Al-20Si, Al-50Cu, Al-10Mg, Al-30Zn, Al-10Mn, Al-10Zr, Al-5Ti, Al-La and Al-Ce according to the composition mass ratio. Melt the aluminum ingots under argon protection at a flow rate of 10L / min. Heat the aluminum ingots to 750℃, add the master alloys for rare earth modification treatment, and hold for 18min. After melting, cool the melt to 720℃, add the nanocomposite particle preforms prepared in S1, and then stir using a rotary electromagnetic stirrer at a frequency of 80Hz, a stirring intensity of 1.0T, and a stirring time of 15min to ensure that the nanoparticles are uniformly dispersed in the melt. S3: Add a mixed refining agent of hexachloroethane and sodium chloride, accounting for 0.5% of the melt mass, to the melt obtained in S2 for refining and degassing. The refining temperature is 720℃ and the refining time is 15min. After refining, let it stand for 20min. Preheat the mold to 250℃ and use the extrusion casting process to pour the refined melt into a casting. The pressure of extrusion casting is 100MPa. S4: Place the casting obtained in S3 in a heat treatment furnace and perform staged solution treatment: the initial melting point of the alloy is determined in advance by differential scanning calorimetry, the solution temperature is 12℃ lower than the initial melting point of the alloy, the heating rate of the solution treatment is 8℃ / min, the furnace temperature is first raised to 500℃ and held for 2.5h, then raised to 525℃ and held for 3h, after the solution treatment is completed, the casting is quickly quenched into water at 70℃, and the transfer time is 12s; S5: The quenched casting obtained in S4 is subjected to a two-stage aging treatment: First, the casting is heated to 130℃ at a rate of 3.5℃ / min and held for 6 hours. After holding, air is introduced to cool the casting to room temperature. Then, the casting is heated to 175℃ at a rate of 3.5℃ / min and held for 4 hours. After completion, air is introduced to cool the casting to room temperature to obtain the final product. Example 2

[0027] A high-strength, wear-resistant, recycled cast aluminum alloy, comprising the following components by weight percentage: Si: 6.8%, Mg: 0.7%, Cu: 1.8%, Zn: 2.0%, Mn: 0.62%, Zr: 0.20%, Ti: 0.25%, Fe: 0.45%, nano TiC particles: 1.00%, nano SiC particles: 0.25%, La: 0.35%, Ce: 0.20%, with the balance being Al and unavoidable impurities.

[0028] The mass ratio of Mn to Fe is 1.38:1, the mass ratio of nano-TiC to nano-SiC is 4:1, the mass ratio of La to Ce is 1.75:1, and the particle size of the nanocomposite particles is 40 nm.

[0029] The preparation method of the above-mentioned high-strength, wear-resistant, recycled cast aluminum alloy includes the following steps: S1: Nano-TiC particles and nano-SiC particles were mixed at a mass ratio of 4:1 and dispersed in anhydrous ethanol. Polyvinylpyrrolidone (PVP) accounting for 4% of the total mass of nanoparticles was added as a surfactant. The mixture was pretreated by high-energy ball milling with a ball-to-particle ratio of 12:1, a milling time of 2 hours, and a milling speed of 500 rpm to obtain a slurry. The slurry was vacuum dried at 80°C for 6 hours to obtain a composite powder. The composite powder was then mixed with aluminum powder at a mass ratio of 1:1 and pressed into a block-shaped preform under a pressure of 300 MPa. The monomer mass of the preform was 50 g. S2: Weigh recycled aluminum ingots and master alloys of Al-20Si, Al-50Cu, Al-10Mg, Al-30Zn, Al-10Mn, Al-10Zr, Al-5Ti, Al-La and Al-Ce according to the composition mass ratio. Melt the aluminum ingots under argon protection at a flow rate of 15L / min. Heat the aluminum ingots to 760℃, add the master alloys for rare earth modification treatment, and hold for 15min. After melting, cool the melt to 730℃, add the nanocomposite particle preforms prepared in S1, and then stir using a rotary electromagnetic stirrer at a frequency of 50Hz, a stirring intensity of 1.5T, and a stirring time of 20min to ensure that the nanoparticles are uniformly dispersed in the melt. S3: Add a mixed refining agent of hexachloroethane and sodium chloride, accounting for 0.3% of the melt mass, to the melt obtained in S2 for refining and degassing. The refining temperature is 730℃ and the refining time is 10min. After refining, let it stand for 15min. Preheat the mold to 200℃ and use the extrusion casting process to pour the refined melt into a casting. The pressure of extrusion casting is 150MPa. S4: Place the casting obtained in S3 in a heat treatment furnace and perform staged solution treatment: the initial melting point of the alloy is determined in advance by differential scanning calorimetry, the solution temperature is 15℃ lower than the initial melting point of the alloy, the heating rate of the solution treatment is 10℃ / min, the furnace temperature is first raised to 500℃ and held for 2h, then raised to 520℃ and held for 4h, after the solution treatment is completed, the casting is quickly quenched into 60℃ water, and the transfer time is 10s; S5: The quenched casting obtained in S4 is subjected to a two-stage aging treatment: First, the casting is heated to 125℃ at a rate of 2℃ / min and held for 8 hours. After holding, air is introduced to cool the casting to room temperature. Then, the casting is heated to 170℃ at a rate of 2℃ / min and held for 5 hours. After completion, air is introduced to cool the casting to room temperature to obtain the final product. Example 3

[0030] A high-strength, wear-resistant, recycled cast aluminum alloy, comprising the following components by weight percentage: Si: 8.0%, Mg: 1.1%, Cu: 1.2%, Zn: 2.8%, Mn: 0.9%, Zr: 0.35%, Ti: 0.15%, Fe: 0.70%, nano TiC particles: 0.60%, nano SiC particles: 0.20%, La: 0.50%, Ce: 0.25%, balance being Al and unavoidable impurities.

[0031] The mass ratio of Mn to Fe is 1.29:1, the mass ratio of nano-TiC to nano-SiC is 3:1, the mass ratio of La to Ce is 2:1, and the particle size of the nanocomposite particles is 60 nm.

[0032] The preparation method of the above-mentioned high-strength, wear-resistant, recycled cast aluminum alloy includes the following steps: S1: Nano-TiC particles and nano-SiC particles were mixed at a mass ratio of 3:1 and dispersed in anhydrous ethanol. Polyvinylpyrrolidone (PVP) accounting for 6% of the total mass of nanoparticles was added as a surfactant. The mixture was pretreated by high-energy ball milling with a ball-to-particle ratio of 8:1, a milling time of 4 hours, and a milling speed of 300 rpm to obtain a slurry. The slurry was vacuum dried at 60°C for 12 hours to obtain a composite powder. The composite powder was then mixed with aluminum powder at a mass ratio of 1:3 and pressed into a block-shaped preform under a pressure of 200 MPa. The monomer mass of the preform was 200 g. S2: Weigh recycled aluminum ingots and master alloys of Al-20Si, Al-50Cu, Al-10Mg, Al-30Zn, Al-10Mn, Al-10Zr, Al-5Ti, Al-La and Al-Ce according to the composition mass ratio. Melt the aluminum ingots under argon protection at a flow rate of 5L / min. Heat the aluminum ingots to 730℃, add the master alloys for rare earth modification treatment, and hold for 20min. After melting, cool the melt to 710℃, add the nanocomposite particle preforms prepared in S1, and then stir using a rotary electromagnetic stirrer at a frequency of 100Hz, a stirring intensity of 0.5T, and a stirring time of 10min to ensure that the nanoparticles are uniformly dispersed in the melt. S3: Add a mixed refining agent of hexachloroethane and sodium chloride at a mass of 0.8% of the melt mass to the melt obtained in S2 for refining and degassing. The refining temperature is 710℃ and the refining time is 20min. After refining, let it stand for 25min. Preheat the mold to 300℃ and use the squeeze casting process to pour the refined melt into a casting. The squeeze casting pressure is 50MPa. S4: Place the casting obtained in S3 in a heat treatment furnace and perform staged solution treatment: the initial melting point of the alloy is determined in advance by differential scanning calorimetry, the solution temperature is 10℃ lower than the initial melting point of the alloy, the heating rate of the solution treatment is 5℃ / min, the furnace temperature is first raised to 500℃ and held for 3h, then raised to 520℃ and held for 2h, after the solution treatment is completed, the casting is quickly quenched into water at 80℃, and the transfer time is 15s; S5: Perform a two-stage aging treatment on the quenched casting obtained in S4: First, heat the casting to 140℃ at a rate of 5℃ / min and hold for 5 hours. After holding, introduce air to cool the casting to room temperature. Then, heat the casting to 180℃ at a rate of 5℃ / min and hold for 3 hours. After completion, introduce air to cool the casting to room temperature to obtain the final product. Example 4

[0033] A high-strength, wear-resistant, recycled cast aluminum alloy, comprising the following components by weight percentage: Si: 6.5%, Mg: 0.6%, Cu: 1.6%, Zn: 2.2%, Mn: 0.7%, Zr: 0.18%, Ti: 0.28%, Fe: 0.50%, nano TiC particles: 0.90%, nano SiC particles: 0.30%, La: 0.45%, Ce: 0.15%, balance being Al and unavoidable impurities.

[0034] The mass ratio of Mn to Fe is 1.40:1, the mass ratio of nano-TiC to nano-SiC is 3:1, the mass ratio of La to Ce is 3:1, and the particle size of the nanocomposite particles is 30 nm.

[0035] The preparation method of the above-mentioned high-strength, wear-resistant, recycled cast aluminum alloy includes the following steps: S1: Nano-TiC particles and nano-SiC particles were mixed at a mass ratio of 3:1 and dispersed in anhydrous ethanol. Polyvinylpyrrolidone (PVP) accounting for 5% of the total mass of nanoparticles was added as a surfactant. The mixture was pretreated by high-energy ball milling with a ball-to-particle ratio of 10:1, a milling time of 3.5 h, and a milling speed of 450 rpm to obtain a slurry. The slurry was vacuum dried at 75 °C for 8 h to obtain a composite powder. The composite powder was then mixed with aluminum powder at a mass ratio of 1:2 and pressed into a block-shaped preform under a pressure of 280 MPa. The monomer mass of the preform was 150 g. S2: Weigh recycled aluminum ingots and master alloys of Al-20Si, Al-50Cu, Al-10Mg, Al-30Zn, Al-10Mn, Al-10Zr, Al-5Ti, Al-La and Al-Ce according to the composition mass ratio. Melt the aluminum ingots under argon protection at a flow rate of 12L / min. Heat the aluminum ingots to 745℃, add the master alloys for rare earth modification treatment, and hold for 18min. After melting, cool the melt to 725℃, add the nanocomposite particle preforms prepared in S1, and then stir using a rotary electromagnetic stirrer at a frequency of 70Hz, a stirring intensity of 1.2T, and a stirring time of 18min to ensure that the nanoparticles are uniformly dispersed in the melt. S3: Add a mixed refining agent of hexachloroethane and sodium chloride, accounting for 0.6% of the melt mass, to the melt obtained in S2 for refining and degassing. The refining temperature is 725℃ and the refining time is 18min. After refining, let it stand for 22min. Preheat the mold to 260℃ and use the extrusion casting process to pour the refined melt into a casting. The pressure of extrusion casting is 120MPa. S4: Place the casting obtained in S3 in a heat treatment furnace and perform staged solution treatment: the initial melting point of the alloy is determined in advance by differential scanning calorimetry, the solution temperature is 13℃ lower than the initial melting point of the alloy, the heating rate of the solution treatment is 7℃ / min, the furnace temperature is first raised to 500℃ and held for 2.5h, then raised to 523℃ and held for 3.5h. After the solution treatment is completed, the casting is quickly quenched into water at 75℃, and the transfer time is 13s. S5: The quenched casting obtained in S4 is subjected to a two-stage aging treatment: First, the casting is heated to 135℃ at a rate of 4℃ / min and held for 7 hours. After holding, air is introduced to cool the casting to room temperature. Then, the casting is heated to 178℃ at a rate of 4℃ / min and held for 4.5 hours. After completion, air is introduced to cool the casting to room temperature to obtain the final product.

[0036] Comparative Example 1 A recycled cast aluminum alloy, specifically composed of the following components by mass percentage: Si: 7.2%, Mg: 0.9%, Cu: 1.5%, Zn: 2.5%, Mn: 0.8%, Zr: 0.25%, Ti: 0.20%, Fe: 0.55%, La: 0.40%, Ce: 0.15%, with the balance being Al and unavoidable impurities.

[0037] The preparation method differs from that of Example 1 in that step S1 is omitted; the preformed block described in S1 is not added in step S2; the remaining steps are the same as those in Example 1.

[0038] Comparative Example 2 A recycled cast aluminum alloy, specifically composed of the following components by mass percentage: Si: 7.2%, Mg: 0.9%, Cu: 1.5%, Zn: 2.5%, Mn: 0.8%, Zr: 0.25%, Ti: 0.20%, Fe: 0.55%, nano-TiC particles: 1.0%, La: 0.40%, Ce: 0.15%, with the balance being Al and unavoidable impurities.

[0039] The preparation method differs from that in Example 1 in that only nano-TiC particles are used in step S1, and the total amount of nano-TiC is weighed at 1.0%; the remaining steps are the same as in Example 1.

[0040] Comparative Example 3 A recycled cast aluminum alloy, specifically composed of the following components by mass percentage: Si: 7.2%, Mg: 0.9%, Cu: 1.5%, Zn: 2.5%, Mn: 0.8%, Zr: 0.25%, Ti: 0.20%, Fe: 0.55%, nano-SiC particles: 1.0%, La: 0.40%, Ce: 0.15%, with the balance being Al and unavoidable impurities.

[0041] The preparation method differs from that in Example 1 in that only nano-SiC particles are used in step S1, and the total amount of nano-SiC is weighed at 1.0%; the remaining steps are the same as in Example 1.

[0042] Comparative Example 4 A recycled cast aluminum alloy, specifically composed of the following components by mass percentage: Si: 7.2%, Mg: 0.9%, Cu: 1.5%, Zn: 2.5%, Mn: 0.8%, Zr: 0.25%, Ti: 0.20%, Fe: 0.55%, nano-TiC particles: 0.80%, nano-SiC particles: 0.20%, with the balance being Al and unavoidable impurities.

[0043] The preparation method differs from that of Example 1 in that Al-La and Al-Ce master alloys are not added in step S2; the remaining steps are the same as those in Example 1.

[0044] Comparative Example 5 The commercially available ADC12 recycled aluminum alloy has the following composition by mass percentage: Si: 9.6%, Cu: 2.5%, Mg: 0.3%, Fe: 0.8%, with the balance being Al and unavoidable impurities.

[0045] To verify the technical effects of the present invention, systematic performance tests were conducted on the aluminum alloy samples prepared in Examples 1-4 and Comparative Examples 1-5. The tests included mechanical properties, wear resistance, and high-temperature resistance.

[0046] (1) The mechanical properties were tested according to GB / T 228.1-2021 "Metallic Materials - Tensile Testing" standard, and the results are shown in Table 1: Table 1 Mechanical properties of different aluminum alloys

[0047] As shown in Table 1, the aluminum alloys in the embodiments of the present invention exhibit tensile strengths of 340-357 MPa, yield strengths of 278-301 MPa, elongation of 4.8%-6.2%, and hardness of 146-160 HB. Compared to Comparative Example 1 without nanoparticles, the tensile strength is increased by approximately 27%-33%; compared to Comparative Example 2 reinforced with single TiC, the tensile strength is increased by approximately 7%-12%; compared to Comparative Example 3 reinforced with single SiC, the tensile strength is increased by approximately 15%-21%; and compared to Comparative Example 4, a nano-reinforced alloy without rare earth elements, the tensile strength is increased by approximately 6%-12%, and the elongation is increased by 0.6%-2.0%. The tensile strength of commercially available ADC12 recycled aluminum alloy is only 210 MPa, and the tensile strength of the embodiments of the present invention is increased by approximately 62%-70%.

[0048] (2) Wear resistance was tested according to GB / T 12444.1-2021 "Metallic Materials Wear Test Methods" standard. The ring-block wear test was carried out on the MM-2000 wear testing machine with a load of 196N, a rotation speed of 400r / min, and a test time of 30min. The results are shown in Table 2: Table 2 Wear resistance of different aluminum alloys

[0049] As can be seen from Table 2, the wear rate of the aluminum alloy in the embodiments of the present invention is as low as 0.025-0.032 g / (m²). 2 Compared to Comparative Example 1 without nanoparticles, the wear rate is reduced by approximately 33%-48%; compared to Comparative Example 2 with single TiC reinforcement, the wear rate is reduced by approximately 6%-26%; compared to Comparative Example 3 with single SiC reinforcement, the wear rate is reduced by approximately 20%-38%; and compared to Comparative Example 5 with commercially available ADC12, the wear rate is reduced by approximately 48%-59%.

[0050] Specifically, the wear rate of TiC alone in Comparative Example 2 was 0.034, and the wear rate of SiC alone in Comparative Example 3 was 0.040. The expected value of the linear sum of the two was about 0.035. However, the actual wear rate of TiC and SiC in Example 1 after being compounded in a 4:1 ratio was 0.027, which was significantly lower than the expected value of the linear sum, proving that there is a clear synergistic effect between nano-TiC and SiC.

[0051] (3) The high temperature resistance test was conducted by keeping the sample at 200℃ for 100h and then testing its room temperature mechanical property retention rate. The results are shown in Table 3. Table 3 High Temperature Resistance of Different Aluminum Alloys

[0052] As shown in Table 3, the tensile strength retention rate of the aluminum alloy in the embodiments of the present invention reaches 83.8%-86.5%, and the hardness retention rate reaches 86.5%-89.2%. Compared with Comparative Example 4 which does not contain rare earth elements, the tensile strength retention rate is increased by approximately 5.3%-8.0%, proving that the addition of La and Ce significantly improves the high-temperature stability of the alloy. This is mainly attributed to the thermally stable dispersed phase formed by rare earth elements La / Ce together with nanoparticles, Zr, and Ti, which effectively pins grain boundaries, inhibits grain boundary migration and coarsening of strengthening phases at high temperatures, and enables the material to maintain excellent performance even after long-term use at 200℃.

[0053] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. The illustrative expressions of the above terms in this specification should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0054] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A high-strength, wear-resistant, recycled cast aluminum alloy, characterized in that, By weight percentage, it includes the following components: Si: 6.0-8.5%; Mg: 0.5-1.2%; Cu: 1.0-1.8%; Zn: 1.5-3.0%; Mn: 0.6-1.2%; Zr: 0.15-0.40%; Ti: 0.10-0.30%; Fe: 0.20-0.80%; Nanocomposite particles: 0.5-1.5%; Rare earth elements: 0.3-0.8%; Balance: Al and unavoidable impurities.

2. The high-strength, wear-resistant, recycled cast aluminum alloy according to claim 1, characterized in that, The mass ratio of Mn to Fe is (0.8-1.5):

1.

3. The high-strength, wear-resistant, recycled cast aluminum alloy according to claim 1, characterized in that, The nanocomposite particles are a mixture of nano-TiC and nano-SiC, wherein the mass ratio of nano-TiC to nano-SiC is (2-6):

1.

4. The high-strength, wear-resistant, recycled cast aluminum alloy according to claim 1, characterized in that, The rare earth elements include La and Ce, wherein the mass ratio of La to Ce is 1:1 to 3:

1.

5. The high-strength, wear-resistant, recycled cast aluminum alloy according to claim 1, characterized in that, The particle size of the nanocomposite particles is 20-70 nm.

6. The method for preparing the high-strength, wear-resistant, recycled cast aluminum alloy according to claim 1, characterized in that, Includes the following steps: S1: Nano TiC particles and nano SiC particles are mixed in anhydrous ethanol at a mass ratio, surfactant is added, and the mixture is pretreated by high-energy ball milling to obtain a slurry. The slurry is vacuum dried under heating conditions to obtain a composite powder. The composite powder is then mixed with aluminum powder and pressed into a block-shaped preform. S2: Weigh recycled aluminum ingots and master alloys of Al-20Si, Al-50Cu, Al-10Mg, Al-30Zn, Al-10Mn, Al-10Zr, Al-5Ti, Al-La and Al-Ce according to the composition mass ratio, and melt them under a protective atmosphere. After melting, the melt is cooled, and the nanocomposite particle preforms prepared in S1 are added and stirred. S3: Add refining agent to the melt obtained in S2 for refining and degassing. After refining, let it stand for 15-25 minutes, preheat the mold, and use the extrusion casting process to pour the refined melt into a casting. S4: Place the casting obtained in S3 in a heat treatment furnace and perform staged solution treatment: first raise the furnace temperature to 500℃ and hold for 2-3 hours, then raise the temperature to 520℃-525℃ and hold for 2-4 hours. After solution treatment, quickly quench the casting in water at 60℃-80℃, with a transfer time not exceeding 15 seconds. S5: Perform a two-stage aging treatment on the quenched casting obtained in S4: First, heat the casting to 120℃-140℃ at a rate of 2℃-5℃ / min and hold for 4-8 hours. After holding, introduce air to cool the casting to room temperature. Then, heat the casting to 165℃-185℃ at a rate of 2℃-5℃ / min and hold for 3-6 hours. After completion, introduce air to cool the casting to room temperature to obtain the final product.

7. The preparation method according to claim 6, characterized in that, In step S1, the surfactant is polyvinylpyrrolidone, and the amount added is 3%-6% of the total mass of the nanoparticles; the pretreatment ball-to-particle ratio is (8-12):1, the ball milling time is 2-4 hours, and the ball milling speed is 300-500 rpm; the vacuum drying temperature is 60℃-80℃, and the time is 6-12 hours; the composite powder and aluminum powder are mixed at a mass ratio of 1:(1-3) and pressed into preforms under a pressure of 200-300 MPa; the monomer mass of the preform is 50-200 g.

8. The preparation method according to claim 6, characterized in that, In step S2, the protective atmosphere is argon, and the gas flow rate is 5-15 L / min; the melting process specifically involves: melting aluminum ingots and heating them to 730℃-760℃, adding intermediate alloys for rare earth modification treatment, and holding at that temperature for 15-20 min; before adding the nanocomposite particle preform, the melt is cooled to 710℃-730℃; the stirring process specifically involves: using a rotary electromagnetic stirring device with a stirring frequency of 50-100 Hz, a stirring intensity of 0.5-1.5 T, and a stirring time of 10-20 min, so that the nanoparticles are uniformly dispersed in the melt.

9. The preparation method according to claim 6, characterized in that, In step S3, the refining agent is a mixture of hexachloroethane and sodium chloride, and the amount added is 0.3% to 0.8% of the melt mass; the refining temperature is 710℃-730℃, the refining time is 10-20 min; and the mold preheating temperature is 200℃-300℃.

10. The preparation method according to claim 6, characterized in that, In step S4, the heating rate of the solution treatment is 5℃-10℃ / min, and the solution temperature is 10℃-15℃ lower than the initial melting point of the alloy; the initial melting point of the alloy is determined in advance by differential scanning calorimetry.

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