Ce and TiC / TiB2 synergistically reinforced high-performance Al-Si alloy as well as preparation method and application thereof

Abstract

The invention relates to the technical field of colored metal materials and casting processes, and discloses a Ce and TiC / TiB2 synergistically strengthened high-performance Al-Si alloy as well as a preparation method and application of the Ce and TiC / TiB2 synergistically strengthened high-performance Al-Si alloy. The invention relates to an Al-Si series alloy, which is prepared from the following components in percentage by mass: 5.0 percent to 12.0 percent of Si, 0.2 percent to 4.0 percent of Cu, 2.0 percent to 4.0 percent of Zn, 0.3 percent to 3.0 percent of Mg, 0.2 percent to 0.8 percent of Mn, 0.1 percent to 0.5 percent of Ce, 0.2 percent to 2.5 percent of TiC / TiB2 nano particles and the balance of Al and inevitable impurities. The Al-Si alloy provided by the invention is compact in structure and few in defects such as pores and shrinkage porosity, the tensile strength reaches 368 MPa, the yield strength reaches 238 MPa, the ductility reaches 7.6%, and the Al-Si alloy has both strength and toughness and can meet the application requirements in the fields of automobiles, aerospace, electronics and the like.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metal materials and casting technology, and in particular to a high-performance Al-Si alloy with synergistic strengthening by Ce and TiC / TiB2, its preparation method and application. Background Technology

[0002] Aluminum alloys are widely used in the automotive, aerospace, and electronics industries due to their excellent specific strength, good casting properties, and recyclability. Among them, Al-Si aluminum alloys possess excellent comprehensive mechanical properties and heat resistance, representing an important development direction for high-performance aluminum alloys. However, traditionally cast Al-Si alloys commonly suffer from casting defects such as segregation, porosity, and shrinkage, which affect the alloy's mechanical properties and density, severely limiting their application in high-performance structural components.

[0003] In existing technologies, microalloying (such as Sr and RE modification) can refine eutectic silicon but it is difficult to optimize the distribution of precipitated phases and it is easy to introduce melt oxidation; exogenous micron ceramic particle reinforcement (such as SiC / Al2O3) is prone to serious agglomeration and interface contamination due to poor interfacial wettability, resulting in a decrease in elongation of more than 50%; at the same time, the mismatch of high pressure / low pressure casting process parameters leads to shrinkage porosity and gas defects, making it difficult to achieve a balance between high density and high performance.

[0004] In the reinforcement and modification of aluminum alloys, nanoparticle reinforcement is an effective means to improve their mechanical properties. Among them, TiC and TiB2 nanoparticles have high hardness, high elastic modulus, and good chemical stability, and as reinforcing phases, they can significantly improve the strength and wear resistance of aluminum alloys. However, the current introduction of nanoparticles mostly adopts the direct external addition method, which is prone to problems such as particle agglomeration, uneven dispersion, and poor interfacial bonding, seriously affecting the overall performance of the material. Summary of the Invention

[0005] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. Therefore, one objective of the present invention is to provide an Al-Si alloy.

[0006] The second objective of this invention is to provide a method for preparing such Al-Si alloys.

[0007] The third objective of this invention is to provide applications for this Al-Si alloy.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of the present invention provides an Al-Si alloy comprising the following components in mass percentage: Si 5.0%-12.0%, Cu 0.2%-4.0%, Zn 2.0%-4.0%, Mg 0.3%-3.0%, Mn 0.2%-0.8%, Ce 0.1%-0.5%, TiC / TiB2 nanoparticles 0.2%-2.5%, with the balance being Al and unavoidable impurities.

[0009] In some embodiments of the present invention, the Al-Si alloy is composed of the following components by mass percentage: Si 6.0%-10.5%, Cu 2.5%-4.0%, Zn 2.0%-3.5%, Mg 0.3%-2.5%, Mn 0.2%-0.7%, Ce 0.1%-0.45%, TiC / TiB2 nanoparticles 0.2%-2.5%, with the balance being Al and unavoidable impurities.

[0010] In some preferred embodiments of the present invention, the Al-Si alloy is composed of the following components by mass percentage: Si 6.0%-10.0%, Cu 2.5%-4.0%, Zn 2.0%-3.2%, Mg 0.3%-2.0%, Mn 0.3%-0.6%, Ce 0.15%-0.4%, TiC / TiB2 nanoparticles 0.5%-2.0%, Al 82.0%-88.0%, and unavoidable impurities <0.04%.

[0011] In some embodiments of the present invention, the unavoidable impurities include Fe, C, O and Ca; the mass percentage content of any single impurity is less than 0.01%.

[0012] In some embodiments of the present invention, the Al-Si alloy comprises the following raw materials: pure aluminum, pure zinc, pure magnesium, master alloy and slow-release TiC / TiB2 precursor particles.

[0013] In some embodiments of the present invention, the aluminum content in the pure aluminum is ≥99.999 wt%.

[0014] In some embodiments of the present invention, the zinc content in the pure zinc is ≥99.999 wt%.

[0015] In some embodiments of the present invention, the magnesium content in the pure magnesium is ≥99.999 wt%.

[0016] In some embodiments of the present invention, the intermediate alloy includes Al-Si alloy, Al-Cu alloy, Al-Mn alloy and Al-Ce alloy.

[0017] In some preferred embodiments of the present invention, the intermediate alloy includes Al-20%Si alloy, Al-50%Cu alloy, Al-20%Mn alloy and Al-10%Ce alloy.

[0018] In some embodiments of the present invention, the sustained-release TiC / TiB2 precursor particles are composed of a mixed salt core containing titanium and boron and a carbon-based coating shell.

[0019] Specifically, compared with directly adding TiC / TiB2 nanoparticles, the slow-release TiC / TiB2 precursor particles added in this invention can delay the decomposition of the core within the temperature range of the aluminum alloy melt, thereby starting to release the active components within 2-6 minutes after feeding, and basically completing the release within 6-15 minutes.

[0020] In some embodiments of the present invention, the sustained-release TiC / TiB2 precursor particles are prepared by a method comprising the following steps: mixing a titanium source and a boron source, adding water and a dispersant to obtain a slurry; spray-drying the slurry to obtain precursor particles; and pre-carbonizing the precursor particles after impregnation in a solution containing a carbon source to obtain the sustained-release TiC / TiB2 precursor particles.

[0021] In some embodiments of the present invention, the molar ratio of the titanium source to the boron source in the preparation of the sustained-release TiC / TiB2 precursor particles is 1:(1.5-2.5).

[0022] In some embodiments of the present invention, the titanium source is selected from one of potassium fluorotitanate (K2TiF6), sodium fluorotitanate (Na2TiF6), titanium dioxide (TiO2), titanium powder, and titanium tetrachloride (TiCl4).

[0023] In some embodiments of the present invention, the boron source is selected from potassium fluoroborate (KBF4), sodium fluoroborate (NaBF4), boron oxide (B2O3), anhydrous borax (Na2B4O7), and boron powder.

[0024] In some embodiments of the present invention, the amount of the dispersant is 0.1wt%-0.2wt% of the mass of the sustained-release TiC / TiB2 precursor particles.

[0025] In some embodiments of the present invention, the dispersant is selected from at least one of sodium polyacrylate, sodium carboxymethyl cellulose, cetyltrimethylammonium bromide, polyethylene glycol, and Tween.

[0026] In some embodiments of the present invention, the amount of carbon source used is 5wt%-30wt% of the mass of the slow-release TiC / TiB2 precursor particles.

[0027] In some embodiments of the present invention, the carbon source is selected from at least one of sucrose, glucose, urea, polyethylene glycol, and phenol-formaldehyde resin.

[0028] In some embodiments of the present invention, the solid content in the carbon source-containing solution is 10wt%-40wt%.

[0029] In some embodiments of the present invention, the solvent in the carbon source-containing solution is selected from at least one of water, ethanol, isopropanol, and acetone.

[0030] In some embodiments of the present invention, the immersion time is 1-24 hours.

[0031] In some embodiments of the present invention, the pre-carbonization temperature is 300-400°C.

[0032] The basic principles of this invention are explained as follows: This invention achieves comprehensive optimization of the microstructure and properties of Al-Si alloys through synergistic design of alloying elements and in-situ nanoparticle control, specifically as follows: 1) The proportions of Si, Cu, Zn, and Mg added have a decisive influence on the alloy's properties. This invention, by controlling the Si content to 5.0%-12.0%, not only improves melt fluidity and ensures casting quality, but also forms fine, dispersed Si phases in the eutectic structure, enhancing strength and wear resistance. Introducing 0.2%-4.0% Cu and 0.3%-3.0% Mg into the alloy system utilizes their ease of forming Al2Cu, Mg2Si, and Al-Si-Cu-Mg quaternary complex phases with the Al matrix during aging, thereby providing precipitation strengthening and second-phase strengthening; 2.0%-4.0% Zn, dissolved in the α-Al matrix, provides significant solid solution strengthening, enhancing matrix hardness and strength to some extent. It also interacts with Cu, promoting interfacial phase formation and further strengthening matrix hardness and creep resistance. Mn, on the other hand, forms Al6Mn dispersed phase particles during solidification and subsequent heat treatment. These particles effectively pin dislocations and grain boundaries, significantly hindering recrystallization and grain growth. Furthermore, Mn can co-form a stable (Fe,Mn)Al6 phase with Fe, mitigating the brittleness of the Fe-rich phase and improving the purity and mechanical properties of the casting structure. 2) Introducing a small amount of Ce element, Ce element can preferentially accumulate on the surface of slow-release TiC / TiB2 precursor particles in the melt and play a catalytic role in the thermal decomposition process of carbon-based coating layer, thereby promoting the gradual release of Ti source and B source, and forming a stable Ce-Ti-B composite interface layer on the particle surface, so as to improve the wettability and interfacial bonding strength between particles and aluminum matrix, inhibit particle agglomeration and coarsening of eutectic Si and Fe-rich brittle phase, and achieve grain refinement and interface structure stability. Utilizing its nucleation effect on Si and intermetallic compound phases during solidification, Ce can refine and spheroidize eutectic Si, transforming it from harmful needle-like structures into short rods / granules, accompanied by an increase in the proportion of α-Al equiaxed crystals. It also forms Ce-enriched dispersed phases at grain boundaries, inhibiting the formation / growth of Fe-containing brittle phases and providing morphological passivation, weakening brittle fracture sources, and further ensuring ductility and impact toughness. Compared to traditional Na / Sr modifiers, Ce exhibits better thermal stability, more durable modification effects in high-temperature long-term processes, and higher compatibility with Ti-based modified / particle-reinforced systems. Compared to La, Ce has a superior and more stable modification effect. Sc / Y / Zr elements mainly inhibit grain growth and stabilize recrystallization by forming L12-type metastable phases (Al3Sc, Al3Y, Al3Zr), with little significant modification effect on eutectic Si. In Al-Si alloys, Ce's direct modification effect is superior to Sc / Y / Zr. 3) By adding slow-release TiC / TiB2 precursor particles, the problems of easy agglomeration and poor wettability of directly added TiC / TiB2 nanoparticles are avoided. This allows the TiC / TiB2 nanoparticles to be uniformly dispersed in the alloy. They not only act as heterogeneous nucleation cores for α-Al, significantly refining the grains and improving the density of the microstructure, but also form a multi-scale synergistic effect with dislocations and precipitates under external force, providing particle strengthening and interface strengthening. When the TiC / TiB2 content is controlled at 0.5%-2.0%, the best balance between grain refinement and mechanical property improvement can be achieved.

[0033] This invention achieves a multi-strength mechanism of "precipitation strengthening - solid solution strengthening - dispersion strengthening - grain refinement - interface strengthening" through reasonable composition design and the synergistic effect of Ce element and uniformly dispersed TiC / TiB2 nanoparticles, which effectively improves the microstructure density, strength and ductility of Al-Si alloys.

[0034] A second aspect of the present invention provides a method for preparing the Al-Si alloy described in the first aspect of the present invention, comprising the following steps: S1. Pure aluminum, intermediate alloys (excluding Al-Ce alloy), pure zinc, and pure magnesium are added sequentially and smelted to obtain an alloy liquid. S2. Al-Ce alloy and slow-release TiC / TiB2 precursor particles are added sequentially to the alloy liquid for refining to obtain a refined liquid; S3. The refined liquid is stirred and then vacuum die-cast and partially extruded to obtain the Al-Si alloy.

[0035] In some embodiments of the present invention, the smelting temperature after adding pure aluminum is 720-790°C, and the smelting time is 1-4 hours.

[0036] In some preferred embodiments of the present invention, the smelting temperature after adding pure aluminum is 740-780°C and the smelting time is 1-3 hours.

[0037] In some more preferred embodiments of the present invention, the melting temperature after adding pure aluminum is 750-780°C and the melting time is 1.5-2.5h.

[0038] In some embodiments of the present invention, the melting temperature after adding the intermediate alloy other than the Al-Ce alloy is 730-790°C, and the melting time is 0.5-2.5h.

[0039] In some preferred embodiments of the present invention, the melting temperature after adding the intermediate alloy other than the Al-Ce alloy is 740-780°C, and the melting time is 0.5-2h.

[0040] In some more preferred embodiments of the present invention, the melting temperature after adding the intermediate alloy other than the Al-Ce alloy is 745-760°C, and the melting time is 1-1.5h.

[0041] In some embodiments of the present invention, the smelting temperature after adding pure zinc is 630-730°C, and the smelting time is 0.1-2 hours.

[0042] In some preferred embodiments of the present invention, the smelting temperature after adding pure zinc is 650-720°C, and the smelting time is 0.2-1.5h.

[0043] In some more preferred embodiments of the present invention, the smelting temperature after adding pure zinc is 670-700°C, and the smelting time is 0.3-0.8h.

[0044] In some embodiments of the present invention, the smelting temperature after adding pure magnesium is 650-730°C, and the smelting time is 0.1-1h.

[0045] In some preferred embodiments of the present invention, the smelting temperature after adding pure magnesium is 680-720°C and the smelting time is 0.1-0.8h.

[0046] In some more preferred embodiments of the present invention, the smelting temperature after adding pure magnesium is 690-710°C and the smelting time is 0.1-0.5h.

[0047] In some embodiments of the present invention, the refining temperature after adding the Al-Ce alloy is 630-750°C, and the refining time is 0.1-1h.

[0048] In some preferred embodiments of the present invention, the refining temperature after adding the Al-Ce alloy is 660-725°C, and the refining time is 0.1-0.5h.

[0049] In some more preferred embodiments of the present invention, the refining temperature after adding the Al-Ce alloy is 680-720°C, and the refining time is 0.2-0.4h.

[0050] In some embodiments of the present invention, the refining temperature after adding the slow-release TiC / TiB2 precursor particles is 700℃-780℃, and the refining time is 0.1-0.5h.

[0051] In some preferred embodiments of the present invention, the refining temperature after adding the slow-release TiC / TiB2 precursor particles is 730℃-770℃, and the refining time is 0.1-0.3h.

[0052] In some embodiments of the present invention, the sustained-release TiC / TiB2 precursor particles are added in 3-4 portions, with an interval of 2-5 minutes between each addition.

[0053] Specifically, the stepwise addition and sequential melting process of pure aluminum, intermediate alloys (excluding Al-Ce alloy), pure zinc, and pure magnesium ensures that each element is fully dissolved and uniformly dispersed in the melt, avoiding local segregation and quality defects caused by overheating. The Al-Ce alloy is added to the alloy melt first, followed by slow-release TiC / TiB2 precursor particles. The Ti and B in the slow-release TiC / TiB2 precursor particles are gradually released within 2-15 minutes and interact with Ce, forming a Ce-Ti-B composite interface layer in situ on the particle surface. This effectively promotes crystal nucleation and refines the grains. The solidification initiation temperature of the melt is increased, reducing the supercooling requirement and resulting in a more uniform microstructure. Optimized control of the melting temperature and time process parameters ensures both the efficiency and stability of alloy melting and significantly improves the purity and density of the final ingot.

[0054] In some embodiments of the present invention, the stirring method includes a combination of mechanical and ultrasonic stirring.

[0055] In some embodiments of the present invention, the vibration power of the ultrasonic stirring is 200-3000W, the resonant frequency is 10-35kHz, and the vibration time is 3-10min.

[0056] In some preferred embodiments of the present invention, the vibration power of the ultrasonic stirring is 800-2000W, the resonant frequency is 20-25kHz, and the vibration time is 5-8min.

[0057] Specifically, the refining liquid is subjected to a combination of mechanical and ultrasonic stirring. Mechanical stirring enables the reactants to disperse rapidly in the aluminum liquid, ensuring macroscopic uniformity. Ultrasonic stirring utilizes the cavitation effect to promote salt decomposition and in-situ reactions, effectively refining and dispersing TiC / TiB2 nanoparticles while removing hydrogen and inclusions, thus improving the purity of the aluminum liquid. Through the synergistic effect of these two methods, the dispersibility and interfacial bonding of TiC / TiB2 nanoparticles can be significantly improved, resulting in aluminum alloy ingots with uniform microstructure and excellent mechanical properties.

[0058] In some embodiments of the present invention, the vacuum die casting has a vacuum degree of 30-80 mbar; the pouring temperature is 720-750℃; and the filling is carried out in two stages, with the first stage filling speed being 0.1-0.4 m / s and the second stage filling speed being 1.5-4.5 m / s.

[0059] In some preferred embodiments of the present invention, the vacuum die casting has a vacuum degree of 30-80 mba; the pouring temperature is 720-750℃; and the filling is carried out in two stages, with the first stage filling speed being 0.2-0.4 m / s and the second stage filling speed being 1.8-4.1 m / s.

[0060] In some embodiments of the present invention, the pressure of the local extrusion is 40-100 MPa, and the holding time is 10-60 s.

[0061] In some preferred embodiments of the present invention, the pressure of the local extrusion is 50-100 MPa, and the holding time is 20-60 s.

[0062] Specifically, the present invention applies pressure to a local area by means of local extrusion needles arranged in a specific part of the mold, and maintains the pressure, which can further compact the melt and suppress shrinkage cavities and porosity defects.

[0063] Specifically, in vacuum die casting, if the pouring temperature is below 720℃, the melt fluidity is insufficient, easily leading to incomplete filling and cold shut defects. If the pouring temperature is above 750℃, it will exacerbate the formation of oxide inclusions and increase the solubility of hydrogen in the aluminum melt, thus increasing the tendency for porosity. During the filling process, the first stage uses a low-speed filling rate of 0.1-0.4 m / s to ensure the smooth flow of the liquid alloy in the mold and prevent turbulence and agglomeration of nano-TiC / TiB2 particles. The second stage uses a high-speed filling rate of 1.5-4.5 m / s to ensure sufficient filling of thin-walled or locally complex structures. If the filling speed is lower or higher than the above range, it will cause cold shuts, shrinkage cavities, particle sedimentation or turbulent porosity, inclusions, and particle segregation, thereby reducing the composite strengthening effect. After filling is completed, applying local pressure of 40-100 MPa by local extrusion needles arranged in specific parts of the mold and maintaining it for 10-60 s can effectively eliminate shrinkage cavities and optimize the uniform distribution of nanoparticles in the matrix. If the local extrusion pressure or holding time deviates from the above range, defects such as excessive local stress in the mold, excessive metal flow, uneven thickness, residual shrinkage cavities, unclosed pores, grain coarsening, and increased residual stress may occur. By synergistically controlling the above filling and local extrusion holding parameters, Al-Si-Cu-Mg based composite aluminum alloy castings with high density, high mechanical properties, and uniform nanoparticle distribution can be obtained.

[0064] The third aspect of the present invention provides the application of the Al-Si alloys described in the first aspect of the present invention in the automotive, aerospace and electronics fields.

[0065] Compared with the prior art, the beneficial effects of the present invention are: 1) The Al-Si alloy provided by this invention, by controlling the content range of Si, Zn, Cu, Mg, and Mn to form the basic framework of the alloy, provides solid solution strengthening and second-phase strengthening. Si, as the matrix of the Al-Si alloy, improves fluidity, ensures casting performance, allows the alloy to fill complex mold cavities, and can also form a eutectic Si phase with Al, improving the alloy's strength and wear resistance. Cu and Mg can form dispersed strengthening phases with Al; these nanoscale precipitates strongly hinder dislocation movement, significantly improving the alloy's yield strength and tensile strength. Zn can dissolve extensively into the α-Al matrix, improving the strength of the matrix itself. Mn neutralizes the harmful effects of Fe, ensuring the alloy's toughness and also... Maintaining a fine-grained microstructure; by adding Ce, the growth habit of eutectic Si is altered, reducing the cutting effect on the α-Al matrix and significantly improving the alloy's toughness; simultaneously, the Ce-rich phase can also promote grain refinement and passivate brittle phases; by adding slow-release TiC / TiB2 precursor particles, the uniform dispersion of TiC / TiB2 nanoparticles is ensured, thereby achieving extreme grain refinement and dispersion strengthening and Orovan strengthening; based on multiple strengthening mechanisms, the resulting Al-Si alloy has a dense microstructure with few defects such as porosity and shrinkage, a tensile strength of 368 MPa, a yield strength of 238 MPa, and an elongation of 7.6%, combining strength and toughness to meet the application requirements of the automotive, aerospace, and electronics industries; 2) The Al-Si alloy provided by this invention, through the synergistic regulation of a specific ratio of Ce element and slow-release TiC / TiB2 precursor particles, allows Ce element to be enriched on the surface of slow-release TiC / TiB2 particles in advance. During the gradual decomposition of the carbon-based coating layer, it catalyzes the release of Ti and B sources, promotes the in-situ formation of a stable Ce-Ti-B composite interface layer on the particle surface, thereby improving the wettability and interfacial bonding strength between the particles and the aluminum matrix, avoiding particle agglomeration, and inhibiting the coarsening of eutectic Si and Fe-rich phases.

[0066] 3) The Al-Si alloy preparation method provided by this invention has simple steps. By adopting a batch melting method, the solute elements are evenly distributed. By controlling the melting temperature and time of each batch, the melting efficiency and product quality are improved. By introducing slow-release TiC / TiB2 precursor particles, problems such as particle agglomeration, uneven dispersion and poor interfacial bonding caused by directly adding nanoparticles are avoided. By ultrasonically vibrating and stirring the refining liquid, a melt with uniform composition and no impurities is obtained. By adopting a low-pressure casting process, porosity and shrinkage defects in the castings are significantly reduced, and the density and overall forming quality of the castings are significantly improved.

[0067] 4) This invention achieves high density and uniform nanoparticle distribution in aluminum alloy castings by optimizing the staged control of filling speed and the local extrusion and holding pressure process. On the one hand, the two-stage filling process (low-speed to high-speed) allows the liquid alloy to flow smoothly in the complex mold, avoiding turbulence, cold shuts, and particle agglomeration, while ensuring sufficient filling of thin-walled and complex structures, thereby significantly reducing defects such as porosity, shrinkage cavities, and inclusions. On the other hand, by applying local extrusion of 40-100 MPa to specific parts of the mold and holding it for 10-60 seconds, shrinkage cavities can be effectively eliminated, the bonding between particles and the matrix interface can be optimized, and the uniform distribution of nanoparticles can be promoted, thus improving the composite strengthening effect. Overall, this invention can obtain Al-Si-Cu-Mg based composite aluminum alloy castings with excellent mechanical properties, dense microstructure, and uniform distribution of strengthening particles, while improving process stability and production reliability, which is significantly better than existing conventional die casting or holding pressure processes. Attached Figure Description

[0068] Figure 1 The image shows the microstructure of the Al-Si alloy prepared in Example 1. Figure 2 The interfacial relationship between Ce element and nanoparticles in the Al-Si alloy prepared in Example 1; Figure 3 The distribution of nanoparticles when using sustained-release TiC / TiB2 precursor particles as raw materials; Figure 4 The distribution of nanoparticles when TiC / TiB2 nanoparticles are used as the raw material; Figure 5 The image shows the microstructure of the Al-Si alloy prepared in Comparative Example 2. Figure 6 The image shows the microstructure of the Al-Si alloy prepared in Comparative Example 5. Figure 7 The solidification curves of Example 1 and Comparative Example 3 are compared. Detailed Implementation The present invention will be further described in detail below through specific embodiments. Unless otherwise specified, the raw materials, reagents, or apparatus used in the embodiments and comparative examples are all available from conventional commercial sources or can be obtained by existing technical methods. Unless otherwise specified, the test or experimental methods are conventional methods in the art.

[0069] The raw materials used in the following examples and comparative examples include: Pure aluminum ingots: Aluminum content ≥ 99.999 wt%, industrial grade; Pure zinc ingots: zinc content ≥99.999wt%, industrial grade; Pure magnesium ingots: magnesium content ≥ 99.999 wt%, industrial grade; Master alloys: Al-20%Si alloy, Al-50%Cu alloy, Al-20%Mn alloy, Al-10%Ce alloy and Al-10%Sr alloy; Slow-release TiC / TiB2 precursor particles: Composed of a mixed salt core containing titanium and boron and a carbon-based coating shell, the preparation method is as follows: Potassium fluorotitanate and potassium fluoroborate (molar ratio of titanium to boron is 1:2) are mixed, and water and sodium carboxymethyl cellulose (15wt% of the mass of the slow-release TiC / TiB2 precursor particles) are added to obtain a slurry; the slurry is spray-dried to obtain precursor particles; the precursor particles are immersed in a sucrose aqueous solution (30wt%) for 12h, and then taken out and pre-carbonized at 350℃ to obtain slow-release TiC / TiB2 precursor particles.

[0070] Example 1 In this embodiment, an Al-Si alloy was prepared. The composition of the Al-Si alloy is shown in Table 1. Table 1. Composition and content of Al-Si alloys in Example 1

[0071] The preparation steps of Al-Si alloys are as follows: S11. According to the Al-Si alloy formula, pure aluminum ingots are added to a melting furnace, heated to 780℃, and held for 2 hours. At this time, the pure aluminum ingots are melted to half their original size. Then, intermediate alloys (Al-20%Si alloy, Al-50%Cu alloy, and Al-20%Mn alloy) are added, the temperature is lowered to 750℃, and the temperature is held for 1.5 hours. After the pure aluminum ingots and intermediate alloys have completely melted, the temperature is lowered to 690℃, pure Zn ingots are added, and the melting process is carried out for 0.3 hours. Then, at the same temperature, pure Mg ingots are added, and the melting process is carried out for 0.2 hours to obtain the alloy liquid. S21. Heat to 700℃, add Al-10%Ce to the alloy liquid, refine for 0.3h, continue to heat to 700℃, add the slow-release TiC / TiB2 precursor particles in four batches with a 3min interval between each addition, refine for 0.2h to obtain the refined liquid. S31. The refining liquid is subjected to mechanical and ultrasonic vibration combined stirring. The ultrasonic stirring vibration power is 1000W, the resonant frequency is 20kHz, and the vibration time is 5min. After the vibration is completed, the slag is removed, and after standing for 10min, it is die-cast. The pouring temperature is 730℃, the vacuum degree of the mold cavity is 60mbar, the filling speed is 0.4m / s in the first stage and 3.2m / s in the second stage, the local extrusion pressure is 75MPa, and the holding time is 50s.

[0072] Example 2 In this embodiment, an Al-Si alloy was prepared. The composition of the Al-Si alloy is shown in Table 2. Table 2. Composition and content of Al-Si alloys in Example 2

[0073] The preparation steps of Al-Si alloys are as follows: S11. According to the Al-Si alloy formula, pure aluminum ingots are added to a melting furnace, heated to 780℃, and held for 2 hours. At this time, the pure aluminum ingots are melted to half their original size. Then, intermediate alloys (Al-20%Si alloy, Al-50%Cu alloy, and Al-20%Mn alloy) are added, the temperature is lowered to 750℃, and the temperature is held for 1.5 hours. After the pure aluminum ingots and intermediate alloys have completely melted, the temperature is lowered to 690℃, pure Zn ingots are added, and the melting process is carried out for 0.3 hours. Then, at the same temperature, pure Mg ingots are added, and the melting process is carried out for 0.2 hours to obtain the alloy liquid. S21. Heat to 700℃, add Al-10%Ce to the alloy liquid, refine for 0.3h, continue to heat to 700℃, add the slow-release TiC / TiB2 precursor particles in four batches with a 3min interval between each addition, refine for 0.2h to obtain the refined liquid. S31. The refining liquid is subjected to mechanical and ultrasonic vibration combined stirring. The ultrasonic stirring vibration power is 1000W, the resonant frequency is 20kHz, and the vibration time is 5min. After the vibration is completed, the slag is removed, and after standing for 10min, it is die-cast. The pouring temperature is 730℃, the vacuum degree of the mold cavity is 60mbar, the filling speed is 0.4m / s in the first stage and 3.2m / s in the second stage, the local extrusion pressure is 70MPa, and the holding time is 50s.

[0074] Example 3 In this embodiment, an Al-Si alloy was prepared. The composition of the Al-Si alloy is shown in Table 3. Table 3. Composition and content of Al-Si alloys in Example 3

[0075] The preparation steps of Al-Si alloys are as follows: S11. According to the Al-Si alloy formula, pure aluminum ingots are added to a melting furnace, heated to 780℃, and held for 2 hours. At this time, the pure aluminum ingots are melted to half their original size. Then, intermediate alloys (Al-20%Si alloy, Al-50%Cu alloy, and Al-20%Mn alloy) are added, the temperature is lowered to 750℃, and the temperature is held for 1.5 hours. After the pure aluminum ingots and intermediate alloys have completely melted, the temperature is lowered to 690℃, pure Zn ingots are added, and the melting process is carried out for 0.3 hours. Then, at the same temperature, pure Mg ingots are added, and the melting process is carried out for 0.2 hours to obtain the alloy liquid. S21. Heat to 700℃, add Al-10%Ce to the alloy liquid, refine for 0.3h, continue to heat to 700℃, add the slow-release TiC / TiB2 precursor particles in four batches with a 3min interval between each addition, refine for 0.2h to obtain the refined liquid. S31. The refining liquid is subjected to mechanical and ultrasonic vibration combined stirring. The ultrasonic stirring power is 1000W, the resonant frequency is 20kHz, and the vibration time is 5min. After the vibration is completed, the slag is removed, and after standing for 10min, it is die-cast. The pouring temperature is 730℃, the vacuum degree of the mold cavity is 60mbar, the filling speed is 0.4m / s in the first stage and 3.2m / s in the second stage, the local extrusion pressure is 65MPa, and the holding time is 50s.

[0076] Example 4 In this embodiment, an Al-Si alloy was prepared. The composition of the Al-Si alloy is shown in Table 4. Table 4. Composition and content of Al-Si alloys in Example 4

[0077] The preparation steps of Al-Si alloys are as follows: S11. According to the Al-Si alloy formula, pure aluminum ingots are added to a melting furnace, heated to 780℃, and held for 2 hours. At this time, the pure aluminum ingots are melted to half their original size. Then, intermediate alloys (Al-20%Si alloy, Al-50%Cu alloy, and Al-20%Mn alloy) are added, the temperature is lowered to 750℃, and the temperature is held for 1.5 hours. After the pure aluminum ingots and intermediate alloys have completely melted, the temperature is lowered to 690℃, pure Zn ingots are added, and the melting process is carried out for 0.3 hours. Then, at the same temperature, pure Mg ingots are added, and the melting process is carried out for 0.2 hours to obtain the alloy liquid. S21. Heat to 700℃, add Al-10%Ce to the alloy liquid, refine for 0.3h, continue to heat to 700℃, add the slow-release TiC / TiB2 precursor particles in four batches with a 3min interval between each addition, refine for 0.2h to obtain the refined liquid. S31. The refining liquid is subjected to mechanical and ultrasonic vibration combined stirring. The ultrasonic stirring vibration power is 1000W, the resonant frequency is 20kHz, and the vibration time is 5min. After the vibration is completed, the slag is removed, and after standing for 10min, it is die-cast. The pouring temperature is 720℃, the mold cavity vacuum degree is 80mbar, the filling speed is 0.5m / s in the first stage and 4.0m / s in the second stage, the local extrusion pressure is 80MPa, and the holding time is 60s.

[0078] Comparative Example 1 This comparative example prepares an Al-Si alloy, which differs from Example 1 in the content of each constituent element. The composition of the Al-Si alloy is shown in Table 5: Table 5. Composition and content of Al-Si alloys in Comparative Example 1

[0079] The preparation steps of Al-Si alloys are as follows: S11. According to the Al-Si alloy formula, pure aluminum ingots are added to a melting furnace, heated to 780℃, and held for 2 hours. At this time, the pure aluminum ingots are melted to half their original size. Then, intermediate alloys (Al-20%Si alloy, Al-50%Cu alloy, and Al-20%Mn alloy) are added, the temperature is lowered to 750℃, and the temperature is held for 1.5 hours. After the pure aluminum ingots and intermediate alloys have completely melted, the temperature is lowered to 690℃, pure Zn ingots are added, and the melting process is carried out for 0.3 hours. Then, at the same temperature, pure Mg ingots are added, and the melting process is carried out for 0.2 hours to obtain the alloy liquid. S21. Heat to 700℃, add Al-10%Ce to the alloy liquid, refine for 0.3h, continue to heat to 700℃, add the slow-release TiC / TiB2 precursor particles in four batches with a 3min interval between each addition, refine for 0.2h to obtain the refined liquid. S31. The refining liquid is subjected to mechanical and ultrasonic vibration combined stirring. The ultrasonic stirring vibration power is 1000W, the resonant frequency is 20kHz, and the vibration time is 5min. After the vibration is completed, the slag is removed, and after standing for 10min, it is die-cast. The pouring temperature is 730℃, the vacuum degree of the mold cavity is 60mbar, the filling speed is 0.4m / s in the first stage and 3.2m / s in the second stage, the local extrusion pressure is 75MPa, and the holding time is 50s.

[0080] Comparative Example 2 This comparative example prepares an Al-Si alloy, which differs from Example 1 in that it does not contain the rare earth element Ce. The composition of the Al-Si alloy is shown in Table 6: Table 6. Composition and content of Al-Si alloys in Comparative Example 2

[0081] The preparation steps of Al-Si alloys are as follows: S11. According to the Al-Si alloy formula, pure aluminum ingots are added to a melting furnace, heated to 780℃, and held for 2 hours. At this time, the pure aluminum ingots are melted to half their original size. Then, intermediate alloys (Al-20%Si alloy, Al-50%Cu alloy, and Al-20%Mn alloy) are added, the temperature is lowered to 750℃, and the temperature is held for 1.5 hours. After the pure aluminum ingots and intermediate alloys have completely melted, the temperature is lowered to 690℃, pure Zn ingots are added, and the melting process is carried out for 0.3 hours. Then, at the same temperature, pure Mg ingots are added, and the melting process is carried out for 0.2 hours to obtain the alloy liquid. S21. Heat to 700℃, add the slow-release TiC / TiB2 precursor particles in four portions, with a 3-minute interval between each addition, and refine for 0.2 hours to obtain the refined liquid. S31. The refining liquid is subjected to mechanical and ultrasonic vibration combined stirring. The ultrasonic stirring vibration power is 1000W, the resonant frequency is 20kHz, and the vibration time is 5min. After the vibration is completed, the slag is removed, and after standing for 10min, it is die-cast. The vacuum degree of the mold cavity is 60mbar, the filling speed is 0.4m / s in the first stage and 3.2m / s in the second stage, the local extrusion pressure is 75MPa, and the holding time is 50s.

[0082] Comparative Example 3 This comparative example prepares an Al-Si alloy, which differs from Example 1 in that it does not contain nanoparticles TiC / TiB2, but introduces a traditional Al-5Ti-1B refining agent. The composition of the Al-Si alloy is shown in Table 7: Table 7. Composition and content of Al-Si alloys in Comparative Example 3

[0083] The preparation steps of Al-Si alloys are as follows: S11. According to the Al-Si alloy formula, pure aluminum ingots are added to a melting furnace, heated to 780℃, and held for 2 hours. At this time, the pure aluminum ingots are melted to half their original size. Then, intermediate alloys (Al-20%Si alloy, Al-50%Cu alloy, and Al-20%Mn alloy) are added, the temperature is lowered to 750℃, and the temperature is held for 1.5 hours. After the pure aluminum ingots and intermediate alloys have completely melted, the temperature is lowered to 690℃, pure Zn ingots are added, and the melting process is carried out for 0.3 hours. Then, at the same temperature, pure Mg ingots are added, and the melting process is carried out for 0.2 hours to obtain the alloy liquid. S21. Heat to 700℃, add Al-10%Ce to the alloy liquid, refine for 0.3h, then add Al-5Ti-1B refining agent, refine for 0.2h to obtain the refined liquid; S31. The refining liquid is subjected to a combination of mechanical and ultrasonic vibration stirring. The ultrasonic stirring power is 1000W, the resonant frequency is 20kHz, and the vibration time is 5min. After the vibration is completed, the slag is removed, and after standing for 10min, it is formed by low-pressure casting. The pouring temperature is 730℃, the vacuum degree of the mold cavity is 60mbar, the filling speed is 0.4m / s in the first stage and 3.2m / s in the second stage, the local extrusion pressure is 75MPa, and the holding time is 50s.

[0084] Comparative Example 4 This comparative example prepares an Al-Si alloy, which differs from Example 1 in that it uses Sr for modification but not Ce. The composition of the Al-Si alloy is shown in Table 8. Table 8. Composition and content of Al-Si alloys in Comparative Example 4

[0085] The preparation steps of Al-Si alloys are as follows: S11. According to the Al-Si alloy formula, pure aluminum ingots are added to a melting furnace, heated to 780℃, and held for 2 hours. At this time, the pure aluminum ingots are melted to half their original size. Then, intermediate alloys (Al-20%Si alloy, Al-50%Cu alloy, and Al-20%Mn alloy) are added, the temperature is lowered to 750℃, and the temperature is held for 1.5 hours. After the pure aluminum ingots and intermediate alloys have completely melted, the temperature is lowered to 690℃, pure Zn ingots are added, and the melting process is carried out for 0.3 hours. Then, at the same temperature, pure Mg ingots are added, and the melting process is carried out for 0.2 hours to obtain the alloy liquid. S21. Heat to 700℃, add Al-10%Sr alloy to the alloy liquid, refine for 0.3h, continue to heat to 700℃, add the slow-release TiC / TiB2 precursor particles in four batches with a 3min interval between each addition, refine for 0.2h to obtain the refined liquid. S31. The refining liquid is subjected to mechanical and ultrasonic vibration combined stirring. The ultrasonic stirring vibration power is 1000W, the resonant frequency is 20kHz, and the vibration time is 5min. After the vibration is completed, the slag is removed, and after standing for 10min, it is die-cast. The vacuum degree of the mold cavity is 60mbar, the filling speed is 0.4m / s in the first stage and 3.2m / s in the second stage, the local extrusion pressure is 75MPa, and the holding time is 50s.

[0086] Comparative Example 5 This comparative example prepares an Al-Si alloy with the same composition as in Example 1, the difference being the die-casting process conditions. The preparation steps of the Al-Si alloy are as follows: S11. According to the Al-Si alloy formula, pure aluminum ingots are added to a melting furnace, heated to 780℃, and held for 2 hours. At this time, the pure aluminum ingots are melted to half their original size. Then, intermediate alloys (Al-20%Si alloy, Al-50%Cu alloy, and Al-20%Mn alloy) are added, the temperature is lowered to 750℃, and the temperature is held for 1.5 hours. After the pure aluminum ingots and intermediate alloys have completely melted, the temperature is lowered to 690℃, pure Zn ingots are added, and the melting process is carried out for 0.3 hours. Then, at the same temperature, pure Mg ingots are added, and the melting process is carried out for 0.2 hours to obtain the alloy liquid. S21. Heat to 700℃, add Al-10%Ce to the alloy liquid, refine for 0.3h, continue to heat to 700℃, add the slow-release TiC / TiB2 precursor particles in four batches with a 3min interval between each addition, refine for 0.2h to obtain the refined liquid. S31. The refining liquid is subjected to mechanical and ultrasonic vibration combined stirring. The ultrasonic stirring vibration power is 1000W, the resonant frequency is 20kHz, and the vibration time is 5min. After the vibration is completed, the slag is removed, and after standing for 10min, it is die-cast. The pouring temperature is 700℃, the vacuum degree of the mold cavity is 10mbar, the filling speed is 0.1m / s in the first stage and 4.2m / s in the second stage, the local extrusion pressure is 30MPa, and the holding time is 10s.

[0087] Comparative Example 6 This comparative example prepares an Al-Si alloy with the same composition as in Example 1, except that the alloy is prepared using a conventional gravity casting process in step S31.

[0088] Comparative Example 7 This comparative example prepares an Al-Si alloy with the same composition as in Example 1, except that the alloy is prepared using a conventional pressure casting process in step S31.

[0089] Performance testing 1. The microstructure of the Al-Si alloys prepared in Example 1, Comparative Example 2, and Comparative Example 5 was observed and analyzed using a metallographic microscope: Figure 1 The image shows the microstructure of the Al-Si alloy prepared in Example 1. Figure 1 It is known that the alloy structure prepared by adding Si, Zn, Cu, Mg, Mn, Ce elements and slow-release TiC / TiB2 precursor particles in a specific ratio, combined with ultrasonic stirring, vacuum die casting and local extrusion molding process and its specific process parameters, is dense and has few defects. Figure 2 The interfacial relationship between Ce element and nanoparticles in the Al-Si alloy prepared in Example 1 is shown by... Figure 2It is known that Al-Ce alloy is first added to the alloy liquid, and then slow-release TiC / TiB2 precursor particles are added. Ti and B in the slow-release TiC / TiB2 precursor particles can be gradually released and react with Ce to form a Ce-Ti-B composite interface layer in situ on the particle surface. This composite interface layer can effectively promote crystal nucleation and refine the grains.

[0090] Figure 3 The image shows the nanoparticle distribution when using sustained-release TiC / TiB2 precursor particles as the raw material. Figure 4 The distribution of nanoparticles when TiC / TiB2 nanoparticles are used as the raw material is shown. Figure 3 and Figure 4 It is known that directly adding TiC / TiB2 nanoparticles leads to particle agglomeration, uneven dispersion, and poor interfacial bonding. However, adding slow-release TiC / TiB2 precursor particles can delay the decomposition of the core within the temperature range of the aluminum alloy melt, greatly reducing particle agglomeration. The nanoparticles are evenly dispersed, which is more conducive to enhancing the mechanical properties of the alloy.

[0091] Figure 5 The image shows the microstructure of the Al-Si alloy prepared in Comparative Example 2. Figure 5 It can be seen that, due to the absence of Ce element in the alloy of Comparative Example 2, the alloy structure is coarse, the grain distribution is uneven, and the α-Al dendrites are coarse. This is because, without the addition of any trace alloying elements, a second phase containing trace alloying elements cannot be formed in the alloy matrix, and thus cannot play a role in refining the grains.

[0092] Figure 6 The image shows the microstructure of the Al-Si alloy prepared in Comparative Example 5. Figure 6 It can be seen that in Comparative Example 5, due to the low pouring temperature and slow cooling rate, the grain structure is uneven and there are pore defects. The low vacuum degree of the die casting mold and the insufficient local extrusion pressure result in the defects not being improved. This shows that the alloy element composition and casting process parameters will affect the microstructure of the alloy.

[0093] 2. The mechanical properties of the Al-Si alloy ingots prepared in Examples 1-4 and Comparative Examples 1-7 were tested. The tensile test was performed on a WGW-100H universal testing machine. The tensile strength and yield strength were tested according to GB / T228.1-2021 (Metallic materials, tensile testing - Part 1: Room temperature test method). The elongation was tested according to GBT17737.308-2018 "Coaxial communication cables" Part 1-308: Mechanical test method - Tensile strength and elongation test of copper-clad metal.

[0094] Table 9. Mechanical property test results of Al-Si alloy ingots prepared in Examples 1-4 and Comparative Examples 1-7

[0095] Table 9 shows the mechanical property test results of the Al-Si alloy ingots prepared in Examples 1-4 and Comparative Examples 1-7. As can be seen from Table 9, the tensile strength of the Al-Si alloy ingots in Examples 1-4 is 352-368 MPa, the yield strength is 218-238 MPa, and the elongation is 6.8%-7.6%. The alloy has good tensile strength, yield strength and elongation, and has both strength and toughness, with excellent mechanical properties.

[0096] In Comparative Example 1, because the content of the basic alloy components was not within the range provided by the present invention, the alloy ratio could not effectively form the second phase strengthening and solid solution strengthening effects, resulting in a significant decrease in alloy performance. This shows that a reasonable composition range is very important for the strengthening effect of the alloy.

[0097] Comparative Example 2 did not introduce Ce, so it could not modify the Si phase and could not serve as a heterogeneous nucleation core to refine the grains. The mechanical properties of the resulting alloy were significantly lower than those of Example 1, and the plasticity was significantly reduced. This shows that the introduction of Ce plays a decisive role in improving the strength and toughness of the alloy.

[0098] Comparative Example 3 did not use slow-release TiC / TiB2 precursor particles, but instead used a conventional Al-5Ti-1B refining agent. The mechanical properties of the alloy were significantly inferior to those of Example 1. Figure 7 The solidification curves of Example 1 and Comparative Example 3 are compared. Figure 7 It can be seen that in Comparative Example 3, the alloy α-Al using the traditional Al-5Ti-1B refining agent began to nucleate at 578.5℃, exhibiting a significant re-glow phenomenon. In Example 1, the alloy α-Al using slow-release TiC / TiB2 precursor particles nucleated at 588℃, with a reduced re-glow phenomenon, and the Al-Si eutectic reaction temperature increased by 1.7℃. This indicates that the slow-release TiC / TiB2 precursor particles promoted α-Al nucleation, thereby promoting the Al-Si eutectic reaction, increasing the initial solidification temperature of the aluminum melt, reducing the supercooling required for solidification, and allowing α-Al nucleation and growth to occur earlier, thus promoting grain refinement.

[0099] In Comparative Example 4, Sr replaced Ce. Ce not only refines α-Al but also forms a dispersed Ce phase with Cu / Fe, effectively reducing the brittleness of intermetallic compounds. Sr can modify eutectic Si but is unable to simultaneously weaken brittle intermetallic compounds (such as Al2Cu and Al5FeSi). Therefore, although the Si morphology is improved to some extent, the brittle phase at the phase interface is still obvious, resulting in the alloy having poorer toughness and overall performance than the Ce system.

[0100] In Comparative Example 5, the casting temperature, vacuum degree, and local extrusion pressure were too low, and the cooling rate was too slow, resulting in insufficient alloy density and an increase in porosity and shrinkage defects. This verifies that the process parameters set in this invention play an important role in ensuring the density of the casting structure and controlling defects.

[0101] In Comparative Example 6, gravity casting was used. Gravity casting has a slow cooling rate and poor melt feeding ability, making it difficult to ensure the compactness of the microstructure. The TiC / TiB2 particles are unevenly distributed and prone to agglomeration, resulting in a significant decrease in the mechanical properties of the alloy.

[0102] Although the die-casting cooling rate was high in Comparative Example 7, gas entrapment was severe, resulting in a high defect rate. Furthermore, it was impossible to ensure uniform dispersion of TiC / TiB2 particles, and the Ce phase effect was weakened, leading to poor yield strength and elongation of the alloy.

Claims

1. An Al-Si alloy, characterized in that, It consists of the following components by mass percentage: Si 5.0%-12.0%, Cu 0.2%-4.0%, Zn 2.0%-4.0%, Mg 0.3%-3.0%, Mn 0.2%-0.8%, Ce 0.1%-0.5%, TiC / TiB2 nanoparticles 0.2%-2.5%, with the balance being Al and unavoidable impurities.

2. The Al-Si alloy according to claim 1, characterized in that, The unavoidable impurities include Fe, C, O and Ca; the mass percentage of any single impurity is less than 0.01%.

3. The Al-Si alloy according to claim 1 or 2, characterized in that, The Al-Si alloy comprises the following raw materials: pure aluminum, pure zinc, pure magnesium, master alloy, and slow-release TiC / TiB2 precursor particles.

4. The Al-Si alloy according to claim 3, characterized in that, The intermediate alloys include Al-Si alloys, Al-Cu alloys, Al-Mn alloys, and Al-Ce alloys.

5. The Al-Si alloy according to claim 3, characterized in that, The sustained-release TiC / TiB2 precursor particles consist of a mixed salt core containing titanium and boron and a carbon-based coating shell.

6. The Al-Si alloy according to claim 5, characterized in that, The sustained-release TiC / TiB2 precursor particles are prepared by a method comprising the following steps: mixing a titanium source and a boron source, adding water and a dispersant to obtain a slurry; spray-drying the slurry to obtain precursor particles; and pre-carbonizing the precursor particles after impregnation in a solution containing a carbon source to obtain the sustained-release TiC / TiB2 precursor particles.

7. The Al-Si alloy according to claim 6, characterized in that, The prepared sustained-release TiC / TiB2 precursor particles have a titanium source to boron source molar ratio of 1:(1.5-2.5) based on the titanium to boron molar ratio. And / or, the pre-carbonization temperature is 300-400°C.

8. The method for preparing the Al-Si alloy according to any one of claims 3-7, characterized in that, Includes the following steps: S1. Pure aluminum, intermediate alloys (excluding Al-Ce alloy), pure zinc, and pure magnesium are added sequentially and smelted to obtain an alloy liquid. S2. Al-Ce alloy and slow-release TiC / TiB2 precursor particles are added sequentially to the alloy liquid for refining to obtain a refined liquid; S3. The refined liquid is stirred and then vacuum die-cast and partially extruded to obtain the Al-Si alloy.

9. The preparation method according to claim 8, characterized in that, The vacuum die casting process involves a vacuum level of 30-80 mbar and a pouring temperature of 720-750℃. The filling process is carried out in two stages: the first stage filling speed is 0.1-0.4 m / s, and the second stage filling speed is 1.5-4.5 m / s. And / or, the pressure of the local extrusion is 40-100MPa, and the holding time is 10-60s.

10. The application of the Al-Si alloy according to any one of claims 1-7 in the automotive, aerospace and electronics fields.

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