A method for producing a high toughness aluminum alloy

Abstract

The application relates to the technical field of aluminum alloy preparation, and discloses a high-toughness aluminum alloy preparation method, which comprises the following steps: putting a pure aluminum ingot into a smelting furnace, heating to 730-740 DEG C to completely melt, adding Mg and Si alloys, stirring to completely dissolve, introducing argon gas to remove gas and slag, and obtaining an aluminum-based melt; cooling the aluminum-based melt to 715-725 DEG C, sequentially adding Al-Sb intermediate alloy and Al-Ca intermediate alloy, first adding the Al-Sb intermediate alloy to stir, then adding the Al-Ca intermediate alloy to stir, and completing composite modification through heat preservation; cooling the modified melt to 708-718 DEG C, adding a composite strengthening agent, adopting ultrasonic treatment, and cooperating with electromagnetic stirring to disperse; after the uniformly dispersed melt is statically placed to remove slag, cooling to 695-705 DEG C to perform metal type gravity casting, adopting air cooling to assist cooling, obtaining an aluminum alloy ingot; and sequentially performing homogenization annealing, solid solution treatment, water quenching and artificial aging on the aluminum alloy ingot to obtain an aluminum alloy; and the application has the effect of improving the toughness of the aluminum alloy.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy preparation technology, and in particular to a method for preparing a high-toughness aluminum alloy. Background Technology

[0002] High-strength, high-toughness, and lightweight aluminum alloys are key structural materials for reducing equipment weight, improving load-bearing capacity, and enhancing energy efficiency in fields such as new energy vehicles, rail transportation, and general machinery. Among them, Al-Mg-Si aluminum alloys have become the preferred matrix material for lightweight components due to their core advantages of controllable heat treatment, excellent welding performance, low forming difficulty, and moderate cost. At present, the performance optimization of this series of aluminum alloys mainly focuses on three directions: modification treatment, grain refinement, and alloying strengthening. However, existing industrial manufacturing technologies still have many insurmountable pain points, which restrict their large-scale application in high-load-bearing and high-impact scenarios.

[0003] Currently, during the smelting and casting process of conventional Al-Mg-Si aluminum alloys, coarse needle-like and elongated Si phases, as well as blocky brittle intermetallic compounds, are easily precipitated inside the matrix. These non-uniform second phases severely disrupt the continuity of the aluminum matrix, becoming sources of stress concentration and directly leading to a significant decrease in the material's plasticity and toughness. Even when modified with a single modifier, the modification effect is generally short-lived, easily fades, and grain boundary segregation is difficult to suppress, failing to fundamentally improve the morphology and distribution of the second phase. This structural defect directly results in the aluminum alloy failing to meet the requirements for lightweight load-bearing components in terms of low-temperature toughness and impact toughness, and thus failing to meet the high toughness requirements for structural materials in fields such as new energy vehicles and rail transportation. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing high-toughness aluminum alloys, which has the effect of improving the toughness of aluminum alloys.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a method for preparing a high-toughness aluminum alloy, comprising the following steps:

[0006] (1) Put pure aluminum ingots into a melting furnace, heat to 730-740℃ and melt completely, add Mg and Si alloy, stir until completely dissolved, and pass argon gas to refine, degas and remove slag to obtain aluminum-based melt;

[0007] (2) Cool the aluminum-based melt to 715-725℃, and add Al-Sb master alloy and Al-Ca master alloy in sequence. First add Al-Sb master alloy and stir for 40-60s, then add Al-Ca master alloy and stir for 90-120s. Hold for 6-8min to complete the composite modification. The mass fraction of Sb in the modified melt is 0.06-0.18wt%, and the mass fraction of Ca is 0.02-0.07wt%.

[0008] (3) Cool the modified melt to 708-718℃, add the composite reinforcing agent, and ultrasonically treat it at 25-35kHz for 8-12 minutes, while dispersing it with electromagnetic stirring at a speed of 300-500r / min. The ultrasonic treatment and electromagnetic stirring are carried out simultaneously. Hold the melt at 3-5 minutes. The mass fraction of nano-TiB2 in the melt is 0.2-0.8wt%, and the mass fraction of Sn is 0.03-0.15wt%.

[0009] (4) After the uniformly dispersed melt is allowed to stand to remove slag, it is cooled to 695-705℃ and then gravity-cast in a metal mold. The preheating temperature of the metal mold is 200-250℃. Air cooling is used to assist cooling, and the cooling rate is ≥50℃ / s to obtain aluminum alloy ingots.

[0010] (5) The aluminum alloy ingot is subjected to homogenization annealing, solution treatment, water quenching and artificial aging in sequence to obtain aluminum alloy; wherein the homogenization annealing temperature is 530-545℃ and the holding time is 3-4h; the solution treatment temperature is 555-565℃ and the holding time is 1.2-1.8h; the water quenching temperature is 30-50℃; and the artificial aging temperature is 175-185℃ and the holding time is 7-9h.

[0011] The present invention is further configured such that the composite reinforcing agent in step (3) comprises nano-TiB2 particles with a particle size of 40-70 nm.

[0012] The present invention is further configured such that the composite reinforcing agent in step (3) also includes an Al-Sn intermediate alloy.

[0013] The present invention is further configured such that the aluminum-based melt in step (1) is an Al-Mg-Si aluminum alloy matrix, wherein the mass fraction of Mg is 0.5-0.9wt%, the mass fraction of Si is 0.7-1.1wt%, and the remainder is Al.

[0014] The present invention is further configured such that the nano-TiB2 particles are dried at 120°C for 2 hours before use, and then wrapped in aluminum foil and pressed into the melt.

[0015] The present invention is further configured such that the mass ratio of the Al-Sb master alloy to the Al-Ca master alloy in step (2) is 2.8-4:1.

[0016] The present invention is further configured such that the aluminum alloy obtained in step (5) has a tensile strength ≥380MPa, a yield strength ≥340MPa, an elongation ≥14%, and a density ≤2.7g / cm³.

[0017] The present invention is further configured such that a high-toughness aluminum alloy prepared by the aforementioned aluminum alloy preparation method has the following composition by mass fraction: Mg 0.5-0.9wt%, Si 0.7-1.1wt%, Sb 0.06-0.18wt%, Ca 0.02-0.07wt%, nano-TiB2 0.2-0.8wt%, Sn 0.03-0.15wt%, with the remainder being Al.

[0018] The beneficial effects of this invention are:

[0019] 1. This invention uses Al-Mg-Si aluminum alloy as the matrix and achieves the strengthening and toughening of aluminum alloy through the coupling of three modified components: Sb-Ca composite modification, nano-TiB2 dispersion reinforcement, and trace Sn alloying. Combined with precise temperature control in segments throughout the process and gravity casting process of metal mold, each component and process link forms an efficient synergistic effect, thereby achieving the strengthening and toughening of aluminum alloy from three aspects: microstructure refinement, interface optimization, and phase structure control.

[0020] Sb and Ca are added in a stepwise manner and in a specific ratio to form a complementary, synergistic, and long-term stable composite modification system. The two achieve synergistic effects from three levels: second phase morphology control, melt purification, and grain boundary optimization. The microscopic mechanism of action is clear and targeted, as follows: First, Sb, as the core modification element for the Si phase, is preferentially added to the aluminum melt and can be quickly adsorbed on the growth interface of the primary Si phase. It precisely inhibits the rapid growth of the Si phase along the preferred crystal orientation, blocks the formation path of coarse needle-like and elongated Si phases, and forces the Si phase to change from a brittle morphology with a high aspect ratio to a fine granular and short rod-like uniformly dispersed morphology with low stress concentration. This eliminates the problem of brittle Si phase interrupting the continuity of the aluminum matrix from the root, alleviates stress concentration, and lays the foundation for improving the plasticity and toughness of the alloy. Secondly, the subsequently added Ca element plays a dual auxiliary and synergistic role. The first role is the purification of the melt and grain boundaries. Ca has a strong ability to deoxidize, desulfurize, and remove impurities. It can preferentially react with harmful impurities such as oxygen and sulfur in the melt to form inert compounds, which are discharged with the refining slag, significantly reducing the inclusion content inside the melt. At the same time, it purifies the grain boundaries and prevents harmful impurities from agglomerating at the grain boundaries and causing grain boundary embrittlement. The second role is to optimize the Sb modification effect and inhibit Sb segregation. Ca can effectively block the excessive enrichment of Sb element at the grain boundaries, prevent the precipitation of brittle phases at the grain boundaries and the decrease in grain boundary bonding caused by single Sb modification. At the same time, it breaks the tendency of Sb atoms to agglomerate, improves the uniformity of Sb in the melt, and expands the effective range of modification. Furthermore, the stepwise addition and orderly reaction of Sb and Ca can form stable composite modification intermediates, avoiding premature reaction losses caused by direct mixing of the two, extending the effective duration of the modification effect, and completely solving the problems of easy degradation and uneven modification effect of single modifiers. This enables full-process controllable regulation of Si phase and brittle intermetallic compounds, and ultimately optimizes the alloy's plasticity, toughness and microstructure uniformity, thereby improving the toughness of conventional Al-Mg-Si aluminum alloys.

[0021] 2. This invention incorporates nano-TiB2 particles with a particle size of 40-70 nm as a composite reinforcing agent. Nano-TiB2 particles possess characteristics such as high melting point, stable crystal structure, and excellent lattice matching with the aluminum matrix. As a highly efficient heterogeneous nucleation core, they form a triple coupling effect with the Sb-Ca composite modification system and the Al-Mg-Si matrix, resulting in nucleation refinement, microstructure complementarity, and non-antagonistic synergy. First, the lattice mismatch between nano-TiB2 and the aluminum matrix is ​​extremely low, satisfying the core conditions for heterogeneous nucleation. After being added to the aluminum melt, it can provide a large number of highly efficient nucleation sites for α-Al matrix grains in the early stage of solidification, significantly improving the grain nucleation rate. At the same time, it inhibits the subsequent growth of α-Al grains through the particle pinning effect, refining traditional coarse columnar and equiaxed crystals to ultrafine uniform equiaxed crystals below 20 μm. This achieves fine grain strengthening at the matrix level, improving both alloy strength and toughness by refining grain boundaries to prevent crack propagation. Secondly, the nano-TiB2 particles and the Sb-Ca composite modification system have excellent compatibility. Their target points do not overlap and complement each other: Sb-Ca focuses on the morphology regulation and grain boundary purification of the second phase Si, while nano-TiB2 focuses on the grain refinement of the α-Al matrix. The two work together to achieve dual ultra-fine refinement of "matrix grains + second phase". At the same time, the nano-TiB2 particles do not react harmfully with Sb and Ca elements, do not consume the effective modification components, and can avoid the decay of modification effect. Instead, they further break down the residual fine brittle phase through dispersion distribution, further reducing the risk of stress concentration. Furthermore, nano-TiB2 particles possess high hardness and strong thermal stability. When uniformly dispersed in the matrix, they can form a dispersion strengthening effect, effectively hindering dislocation slip under external force and improving alloy strength without sacrificing plasticity and toughness. Combined with low-temperature addition at 708-718℃ and ultrasonic-electromagnetic synchronous dispersion process, the problems of nanoparticle agglomeration and segregation can be completely avoided, ensuring that each nano-TiB2 particle can play a role in nucleation and strengthening, achieving a dual superposition of fine grain strengthening and dispersion strengthening, further amplifying the toughness improvement effect brought about by Sb-Ca modification, and achieving the goal of simultaneous optimization of strength and toughness.

[0022] 3. This invention also incorporates an Al-Sn master alloy as a composite strengthening agent. Sn, as a low-cost and mildly effective alloying element, is added in amounts of only 0.03-0.15 wt%, without significantly increasing raw material costs. It can form a full-dimensional complementary synergy with the Sb-Ca composite modification system and the nano-TiB2 reinforcement system, optimizing the microstructure from three dimensions: aging precipitation, interface wettability, and grain boundary regulation. This completely solves the problem of "increased strength leading to decreased toughness." The specific synergistic mechanism is as follows: First, Sn precisely enhances the aging strengthening process of Al-Mg-Si alloys. Sn atoms can dissolve in the aluminum matrix, effectively reducing the diffusion activation energy of aluminum matrix atoms, regulating the precipitation kinetics of the Mg2Si strengthening phase, and slowing down the coarsening rate of the strengthening phase. This promotes the precipitation of a large number of small, uniformly distributed, and appropriately spaced nano-sized Mg2Si strengthening phases during the artificial aging process from the supersaturated solid solution formed after solution treatment. This avoids grain boundary embrittlement caused by the precipitation of coarse strengthening phases, significantly improving the aging strengthening effect and achieving a steady increase in alloy strength. Secondly, Sn can significantly improve the interfacial wettability between nano-TiB2 particles and aluminum melt. Nano-TiB2 particles have high surface energy and are prone to interfacial repulsion with aluminum melt. Sn atoms can preferentially adsorb on the surface of nano-TiB2 particles, reducing the surface energy of the particles, eliminating interfacial voids between the particles and the melt, reducing the tendency of particle agglomeration, and strengthening the interfacial bonding force between the particles and the aluminum matrix. This avoids the formation of stress concentration points due to interfacial debonding, ensuring that the fine grain and dispersion strengthening effects of nano-TiB2 are fully utilized, and further improving the comprehensive mechanical properties of the alloy. Third, the Sn and Sb-Ca composite modification system forms a synergistic optimization effect on grain boundaries. Sn can further inhibit the excessive segregation of Sb and Ca elements at grain boundaries, block the continuous precipitation of brittle intermetallic compounds at grain boundaries, and, together with the purification effect of Ca elements, further purify grain boundaries, thicken the grain boundary transition layer, and improve the grain boundary bonding strength and toughness. At the same time, Sn will not destroy the modification effect of Sb on the Si phase, and will not change the granular dispersion morphology of the Si phase. Instead, it can further refine the size of the residual Si phase, reduce the stress concentration of the structure in all aspects, and achieve the effect of improving strength while ensuring or even further improving the plasticity and toughness of the alloy, thus achieving a synergistic and unified effect of high strength, high toughness, and low cost.

[0023] 4. This invention employs a segmented, precise temperature control process and a gravity casting process using a metal mold throughout the entire process. This provides a stable environment for the synergistic effect of various components, ensuring maximum modification efficiency. Step-by-step cooling at each stage of melting, modification, and strengthening prevents the burning of reactive elements and the agglomeration of nanoparticles. Gravity casting is performed after the metal mold is preheated to 200-250℃, combined with rapid air cooling. This prevents incomplete casting and cold shut defects caused by rapid cooling of the melt, significantly increases the cooling rate, refines the solidification structure, and reduces casting defects. Subsequent dedicated heat treatment further activates the precipitation of strengthening phases, which synergize with the previously modified structure, ultimately achieving a high-toughness aluminum alloy with a uniform structure and stable performance. Detailed Implementation

[0024] The technical solution of the present invention will now be clearly and completely described with reference to specific embodiments. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0025] Raw material specifications

[0026] All raw materials used in this invention are industrial-grade conventional raw materials, with no special customization requirements. Each raw material must meet the following specifications to avoid excessive impurities affecting the alloy properties:

[0027] Pure aluminum ingots: purity ≥ 99.7 wt%, surface free of oxide scale, oil stains, and rust. Before use, wipe with alcohol to remove dirt, dry, and then put into the smelting furnace.

[0028] Alloying element raw materials: Al-Mg master alloy, Al-Si master alloy, Al-Sb master alloy, Al-Ca master alloy, Al-Sn master alloy, all with a purity ≥99.5wt%, alloying element content deviation ≤±0.05wt%, free from agglomeration and oxidation.

[0029] Nano TiB2 particles: Particle size 40-70nm, purity ≥99.0wt%, no agglomeration or clumping, no impurities. Before use, they must be vacuum dried at 120℃ for 2h to remove the adsorbed moisture and prevent the melt from absorbing gas and generating pores during the smelting process.

[0030] Protective gas: High-purity argon, purity ≥ 99.99%;

[0031] Water quenching medium: deionized water, temperature controlled at 30-50℃, free of impurities and suspended matter, to ensure uniform quenching.

[0032] Performance testing methods

[0033] The performance testing of aluminum alloy finished products in this invention strictly follows national standards. Test samples are uniformly processed into standard tensile specimens using wire cutting. Before testing, the specimens are polished with sandpaper to remove surface burrs and processing defects. Specific testing methods and standards are as follows:

[0034] Room temperature tensile properties test: According to GB / T 228.1-2010 "Metallic materials - Tensile testing - Part 1: Room temperature test method", an electronic universal testing machine was used for testing. The loading rate was 2 mm / min. Tensile strength, yield strength and elongation after fracture were tested simultaneously. Each group of samples was tested in parallel 3 times and the average value was taken as the final result.

[0035] Density testing: The water displacement method (Archimedes' principle) was used for testing, according to GB / T 1423-2008 "Methods for Determination of Density of Metallic Materials". Defect-free block samples were selected and the test was repeated 3 times. The error was ≤ ±0.01g / cm³.

[0036] Microstructure observation: The samples were mounted, ground and polished, and then etched with Keller's reagent to observe the grain size, Si phase morphology and nano TiB2 dispersion to verify the modification effect.

[0037] Composition analysis: The mass fraction of each element in the alloy is detected using a direct-reading spectrometer to ensure that the composition meets the requirements and that the impurity content does not exceed the standard.

[0038] The following are specific examples. All raw materials used meet the above specifications, and performance tests are performed according to the above methods. Specific Implementation

[0039] (I) Example 1

[0040] 1. Formula Composition

[0041] Al-Mg-Si matrix: 30g pure Mg, 40g pure Si; 10g Al-Sb master alloy (10wt% Sb content), 3g Al-Ca master alloy (10wt% Ca content), 20g nano TiB2 (50nm particle size), 6g Al-Sn master alloy (10wt% Sn content), total melt mass 5kg, corresponding mass fractions of each element are: Mg 0.6wt%, Si 0.8wt%, Sb 0.10wt%, Ca 0.03wt%, nano TiB2 0.4wt%, Sn 0.06wt%, balance is Al and unavoidable impurities.

[0042] 2. Preparation steps

[0043] (1) 4.795 kg of pure aluminum ingots were put into a resistance melting furnace and heated to 735 °C to melt completely. 30 g of pure Mg and 40 g of pure Si were added and mechanically stirred until completely dissolved. High-purity argon gas was introduced for 10 min to remove gas and slag, and aluminum-based melt was obtained.

[0044] (2) Cool the melt to 720℃, add 10g of Al-Sb master alloy, stir for 50s, add 3g of Al-Ca master alloy, stir for 100s, and keep warm for 7min to complete the composite modification;

[0045] (3) Continue to cool down to 712℃, dry 20g of nano TiB2 particles at 120℃ for 2h, wrap them in aluminum foil and press them into the melt, add 6g of Al-Sn master alloy at the same time, use 30kHz ultrasonic treatment for 10min, and disperse them at the same time with 400r / min electromagnetic stirring, and keep warm for 4min.

[0046] (4) The melt was allowed to stand for 5 minutes to remove the slag, and then cooled to 700°C. Gravity casting was performed using a metal mold preheated to 220°C, with air cooling as an auxiliary cooling method. The cooling rate was controlled at 60°C / s to obtain an aluminum alloy ingot.

[0047] (5) The ingot is subjected to homogenization annealing at 535℃ for 3.5h, cooled to room temperature in the furnace, then solution treated at 560℃ for 1.5h, immediately placed in 40℃ water for quenching, and finally artificially aged at 180℃ for 8h to obtain the finished aluminum alloy.

[0048] (II) Example 2

[0049] 1. Formula Composition

[0050] Al-Mg-Si matrix: 35g pure Mg, 45g pure Si; 14g Al-Sb master alloy (10wt% Sb content), 5g Al-Ca master alloy (10wt% Ca content), 30g nano TiB2 (60nm particle size), 10g Al-Sn master alloy (10wt% Sn content), total melt mass 5kg, corresponding mass fractions of each element are: Mg 0.7wt%, Si 0.9wt%, Sb 0.14wt%, Ca 0.05wt%, nano TiB2 0.6wt%, Sn 0.10wt%, balance is Al and unavoidable impurities.

[0051] 2. Preparation steps

[0052] (1) 4.745 kg of pure aluminum ingots were put into a resistance melting furnace and heated to 730°C to melt completely. 35 g of pure Mg and 45 g of pure Si were added and mechanically stirred until completely dissolved. High-purity argon gas was introduced for 10 min to remove gas and slag, and aluminum-based melt was obtained.

[0053] (2) Cool the melt to 715℃, add 14g of Al-Sb master alloy, stir for 45s, add 5g of Al-Ca master alloy, stir for 110s, and keep warm for 6min to complete the composite modification.

[0054] (3) Continue to cool down to 710℃, dry 30g of nano TiB2 particles at 120℃ for 2h, wrap them in aluminum foil and press them into the melt, add 10g of Al-Sn master alloy at the same time, use 28kHz ultrasonic treatment for 12min, and disperse them at the same time with 350r / min electromagnetic stirring, and keep warm for 5min.

[0055] (4) The melt was allowed to stand for 5 minutes to remove the slag, and then cooled to 698°C. Gravity casting was performed using a metal mold preheated to 200°C, with air cooling as an auxiliary cooling method. The cooling rate was controlled at 55°C / s to obtain an aluminum alloy ingot.

[0056] (5) The ingot is subjected to homogenization annealing at 540℃ for 3 hours, cooled to room temperature in the furnace, then solution treated at 558℃ for 1.8 hours, immediately placed in water quenched at 35℃, and finally artificially aged at 178℃ for 9 hours to obtain the finished aluminum alloy.

[0057] (III) Example 3

[0058] 1. Formula Composition

[0059] Al-Mg-Si matrix: 25g pure Mg, 35g pure Si; 8g Al-Sb master alloy (10wt% Sb content), 2g Al-Ca master alloy (10wt% Ca content), 15g nano TiB2 (40nm particle size), 4g Al-Sn master alloy (10wt% Sn content), total melt mass 5kg, corresponding mass fractions of each element are: Mg 0.5wt%, Si 0.7wt%, Sb 0.08wt%, Ca 0.02wt%, nano TiB2 0.3wt%, Sn 0.04wt%, balance is Al and unavoidable impurities.

[0060] 2. Preparation steps

[0061] (1) 4.823 kg of pure aluminum ingots were put into a resistance melting furnace and heated to 740°C to melt completely. 25 g of pure Mg and 35 g of pure Si were added and mechanically stirred until completely dissolved. High-purity argon gas was introduced for 10 min to remove gas and slag, and aluminum-based melt was obtained.

[0062] (2) Cool the melt to 725℃, add 8g of Al-Sb master alloy, stir for 60s, add 2g of Al-Ca master alloy, stir for 90s, and keep warm for 8min to complete the composite modification;

[0063] (3) Continue to cool down to 718℃, dry 15g of nano TiB2 particles at 120℃ for 2h, wrap them in aluminum foil and press them into the melt, add 4g of Al-Sn master alloy at the same time, use 35kHz ultrasonic treatment for 8min, and disperse them at the same time with 500r / min electromagnetic stirring, and keep warm for 3min.

[0064] (4) The melt was allowed to stand for 5 minutes to remove the slag, and then cooled to 705°C. Gravity casting was performed using a metal mold preheated to 250°C, with air cooling as an auxiliary cooling method. The cooling rate was controlled at 50°C / s to obtain an aluminum alloy ingot.

[0065] (5) The ingot is subjected to homogenization annealing at 530℃ for 4 hours, cooled to room temperature in the furnace, then solution treated at 565℃ for 1.2 hours, immediately placed in 50℃ water for quenching, and finally artificially aged at 185℃ for 7 hours to obtain the finished aluminum alloy.

[0066] Comparative Example

[0067] The following comparative examples, by omitting core components, replacing raw materials, or adjusting processes, are compared with the embodiments to verify the necessity and superiority of the technical solution of the present invention.

[0068] (a) Comparative Example 1 (Missing conductive carbon black-graphite composite powder)

[0069] Comparative Example 1 (Blank control of conventional process)

[0070] Using the same Al-Mg-Si matrix, without adding Sb, Ca, nano TiB2, or Sn, conventional melting and casting were carried out at a melting temperature of 740℃, sand casting, and conventional T6 heat treatment (solution treatment at 560℃ + aging at 170℃). All other process parameters were kept consistent with those in Example 1 to obtain the control aluminum alloy.

[0071] Comparative Example 2 (One-way missing factors: without adding Sb)

[0072] The raw material ratio and process steps were completely identical to those in Example 1, except that Sb element and Al-Sb master alloy were not added. The amount of Ca, nano TiB2, and Sn added, as well as the parameters of the entire process of smelting, modification, casting, and heat treatment, remained unchanged, and a control aluminum alloy was obtained.

[0073] Comparative Example 3 (Single-factor missing: without Ca)

[0074] The raw material ratio and process steps were completely identical to those in Example 1, except that Ca element and Al-Ca master alloy were not added. The addition amounts of Sb, nano TiB2, and Sn, as well as the parameters of the entire process of smelting, modification, casting, and heat treatment, remained unchanged, resulting in a control aluminum alloy.

[0075] Comparative Example 4 (Single-factor missing: no nano-TiB2 added)

[0076] The raw material ratio and process steps were completely identical to those in Example 1, except that nano TiB2 particles were not added. The amounts of Sb, Ca, and Sn added, as well as the parameters of the entire process of smelting, modification, casting, and heat treatment, remained unchanged, resulting in a control aluminum alloy.

[0077] Comparative Example 5 (Single-factor missing: Sn not added)

[0078] The raw material ratio and process steps were completely identical to those in Example 1, except that Sn element and Al-Sn master alloy were not added. The amount of Sb, Ca, and nano TiB2 added, as well as the parameters of the entire process of smelting, modification, casting, and heat treatment, remained unchanged, and a control aluminum alloy was obtained.

[0079] Performance test results

[0080] The mechanical properties of each group of samples were tested according to GB / T 228.1-2010 standard for tensile testing of metallic materials. The results are shown in the table below:

[0081] Test group Tensile strength / MPa Yield strength / MPa Elongation / % <![CDATA[Density / (g / cm 3 )]]> Example 1 396 352 15.2 2.68 Example 2 412 368 14.7 2.69 Example 3 382 341 16.1 2.67 Comparative Example 1 315 278 8.3 2.70 Comparative Example 2 338 302 9.6 2.69 Comparative Example 3 345 310 10.1 2.69 Comparative Example 4 352 318 11.7 2.68 Comparative Example 5 367 330 12.3 2.68

[0082] Table 1 Performance Test Results

[0083] Results Analysis: The aluminum alloys prepared in each embodiment of this invention exhibit significantly superior tensile strength, yield strength, and elongation compared to the conventional process comparison examples and the comparison examples lacking individual factors. The elongation increased by over 70%, the strength increased by over 25%, and the density remained ≤2.7 g / cm³. Comparison with the comparison examples lacking individual factors reveals that the absence of any modifying component significantly reduces the alloy's strength and toughness: the absence of Sb and Ca leads to insufficient modification effects and a substantial decrease in elongation; the absence of nano-TiB2 weakens the grain refinement effect and significantly reduces strength; and the absence of Sn results in insufficient aging strengthening and interface optimization effects, preventing the alloy from achieving optimal strength and toughness. This fully demonstrates that the four components—Sb, Ca, nano-TiB2, and Sn—are indispensable and work synergistically to achieve the optimal effect of high strength, high toughness, and lightweight, which is completely consistent with the synergistic mechanism and technical effects described above, fully proving the feasibility and superiority of the process and component ratio of this invention.

[0084] Test results: The aluminum alloys prepared in the various embodiments of the present invention have tensile strength, yield strength and elongation that are far superior to those of the conventional process comparison ratio. The elongation is increased by more than 70%, the strength is increased by more than 25%, and the density is kept ≤2.7g / cm³, achieving a combination of high strength, high toughness and lightweight.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a high-toughness aluminum alloy, characterized in that, Includes the following steps: (1) Put pure aluminum ingots into a melting furnace, heat to 730-740℃ and melt completely, add Mg and Si alloy, stir until completely dissolved, and pass argon gas to refine, degas and remove slag to obtain aluminum-based melt; (2) Cool the aluminum-based melt to 715-725℃, and add Al-Sb master alloy and Al-Ca master alloy in sequence. First add Al-Sb master alloy and stir for 40-60s, then add Al-Ca master alloy and stir for 90-120s. Hold for 6-8min to complete the composite modification. The mass fraction of Sb in the modified melt is 0.06-0.18wt%, and the mass fraction of Ca is 0.02-0.07wt%. (3) Cool the modified melt to 708-718℃, add the composite reinforcing agent, and ultrasonically treat it at 25-35kHz for 8-12 minutes, while dispersing it with electromagnetic stirring at a speed of 300-500r / min. The ultrasonic treatment and electromagnetic stirring are carried out simultaneously. Hold the melt at 3-5 minutes. The mass fraction of nano-TiB2 in the melt is 0.2-0.8wt%, and the mass fraction of Sn is 0.03-0.15wt%. (4) After the uniformly dispersed melt is allowed to stand to remove slag, it is cooled to 695-705℃ and then gravity-cast in a metal mold. The preheating temperature of the metal mold is 200-250℃. Air cooling is used to assist cooling, and the cooling rate is ≥50℃ / s to obtain aluminum alloy ingots. (5) The aluminum alloy ingot is subjected to homogenization annealing, solution treatment, water quenching and artificial aging in sequence to obtain aluminum alloy; wherein the homogenization annealing temperature is 530-545℃ and the holding time is 3-4h; the solution treatment temperature is 555-565℃ and the holding time is 1.2-1.8h; the water quenching temperature is 30-50℃; and the artificial aging temperature is 175-185℃ and the holding time is 7-9h.

2. The method for preparing a high-toughness aluminum alloy according to claim 1, characterized in that: The composite reinforcing agent mentioned in step (3) includes nano-TiB2 particles with a particle size of 40-70 nm.

3. The method for preparing a high-toughness aluminum alloy according to claim 2, characterized in that: The composite reinforcing agent mentioned in step (3) also includes an Al-Sn intermediate alloy.

4. The method for preparing a high-toughness aluminum alloy according to claim 1, characterized in that: The aluminum-based melt in step (1) is an Al-Mg-Si aluminum alloy matrix, wherein the mass fraction of Mg is 0.5-0.9wt%, the mass fraction of Si is 0.7-1.1wt%, and the remainder is Al.

5. The method for preparing a high-toughness aluminum alloy according to claim 2, characterized in that: The nano-TiB2 particles were dried at 120°C for 2 hours before use, and then wrapped in aluminum foil and pressed into the melt.

6. The method for preparing a high-toughness aluminum alloy according to claim 1, characterized in that: The mass ratio of Al-Sb master alloy to Al-Ca master alloy in step (2) is 2.8-4:

1.

7. The method for preparing a high-toughness aluminum alloy according to claim 1, characterized in that: The aluminum alloy obtained in step (5) has a tensile strength ≥380MPa, a yield strength ≥340MPa, an elongation ≥14%, and a density ≤2.7g / cm³.

8. A high-toughness aluminum alloy prepared by the aluminum alloy preparation method according to any one of claims 1 to 7, characterized in that: By mass fraction, its composition is: Mg 0.5-0.9wt%, Si 0.7-1.1wt%, Sb 0.06-0.18wt%, Ca 0.02-0.07wt%, nano TiB2 0.2-0.8wt%, Sn 0.03-0.15wt%, with the remainder being Al.