A cast aluminum alloy material, a method for preparing the same, and an application thereof
By reducing the use of expensive elements Cu and Ni, adding rare earth elements La and Fe, and employing rapid water cooling and aging treatment, the problems of poor high-temperature mechanical properties and high production costs of aluminum alloy materials have been solved, resulting in low-cost, high-performance aluminum alloy materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI JIAOTONG UNIV
- Filing Date
- 2025-12-30
- Publication Date
- 2026-07-21
AI Technical Summary
Existing aluminum alloy materials have poor mechanical properties at high temperatures and high production costs, mainly due to the addition of expensive Cu and Ni elements, and the increased energy consumption caused by long-term solution treatment.
Cast aluminum alloy materials were prepared by reducing the content of Cu and Ni elements, adding trace amounts of La and Fe elements, and using rapid water cooling and aging treatment.
Significantly reducing material costs while improving the high-temperature mechanical properties of aluminum alloys, resulting in low-cost aluminum alloys with excellent high-temperature performance.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of aluminum alloy materials technology, and in particular to a cast aluminum alloy material, its preparation method, and its application. Background Technology
[0002] As a key component of engines and other equipment, pistons must withstand long-term high-temperature and high-pressure environments during service, thus placing increasingly higher demands on their mechanical properties at both room temperature and high temperature. Al-Si-Mg system is currently a commonly used aluminum alloy piston material on the market, but the Mg2Si phase undergoes significant coarsening at temperatures exceeding 200℃, severely deteriorating its high-temperature mechanical properties.
[0003] Currently, the heat resistance of Al-Si-Mg alloys is mainly improved by adding high amounts of Cu and Ni. Adding high amounts of expensive metals like Cu and Ni can form various heat-resistant phases, such as Al2Cu, Al3Ni, Al3CuNi, and Al7Cu4Ni, significantly improving the mechanical properties of Al-Si-Mg alloys above 300℃. For example, patent CN109735748 A improves the heat resistance of materials by adding 4-6wt% Cu and 2.5-3.5wt% Ni. However, Cu and Ni are expensive, and their large-scale use increases the production cost of aluminum alloy piston materials. Furthermore, most Al-Si-Mg aluminum alloy piston materials undergo long-term solution treatment and aging to improve mechanical properties, further increasing production costs. Therefore, there is an urgent need for an aluminum alloy material that is low-cost and possesses excellent high-temperature mechanical properties. Summary of the Invention
[0004] In view of this, the present invention provides a cast aluminum alloy material, its preparation method and application, to solve the problem that the production cost and high-temperature mechanical properties of existing aluminum alloy materials cannot be effectively balanced.
[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: On one hand, the present invention provides a cast aluminum alloy material, comprising, by mass percentage: Si 11.5-13.5%, Mg 1.5-2.5%, Cu 0.4-0.6%, Ni 0.4-0.65%, Mn 0.1-0.3%, rare earth elements 0.05-0.15%, with the balance being Al and unavoidable impurities.
[0006] Preferably, the cast aluminum alloy material further includes Fe, and the mass percentage of Fe is 0.1-0.7%.
[0007] Preferably, the rare earth element includes at least one of La and Ce.
[0008] On the other hand, the present invention provides a method for preparing the above-mentioned cast aluminum alloy material, comprising the following steps: (1) The raw materials are smelted and cast to obtain ingots; (2) The ingot is water-cooled and then aged to obtain cast aluminum alloy material.
[0009] Preferably, the smelting includes a melting stage and a refining stage performed sequentially.
[0010] Preferably, the melting stage comprises the following steps: mixing pure aluminum ingots, aluminum-silicon master alloys, aluminum-copper master alloys, aluminum-nickel master alloys, and aluminum-manganese master alloys and melting them at 720-740°C; continuing to heat to 760-790°C, adding aluminum-iron master alloys and aluminum-rare earth element master alloys for melting treatment; continuing to cool to 690-700°C, adding pure magnesium ingots for melting to obtain molten metal liquid.
[0011] Preferably, the refining stage involves the following steps: heating the molten metal to 730-750°C, adding 0.8-1.2% of a refining agent by mass of the molten metal, stirring, and allowing it to stand to obtain a refined liquid.
[0012] Preferably, the smelting process further includes a refining and homogenizing stage.
[0013] Preferably, the steps of the refining and homogenizing stage are as follows: cooling the refining liquid to 720-730℃, adding a refining agent, stirring and letting it stand to obtain an alloy liquid.
[0014] Preferably, the amount of the refining agent added is 0.08-0.12% of the refining liquid, based on the mass percentage of titanium in the refining agent.
[0015] Preferably, the refining agent includes at least one of aluminum-titanium-boron, aluminum-titanium-carbon, and aluminum-titanium-carbon-boron master alloys.
[0016] Preferably, the casting temperature is 190-210℃.
[0017] Preferably, the water cooling temperature is 20-40℃ and the cooling time is 8-15s.
[0018] Preferably, the aging treatment temperature is 225-235℃, and the holding time is 4-6 hours.
[0019] Furthermore, the present invention also provides an application of the above-described cast aluminum alloy material or the cast aluminum alloy material prepared by the method described in any one of the above-described methods in an engine piston.
[0020] This invention provides a cast aluminum alloy material, its preparation method, and its application. Compared with the prior art, its advantages are as follows: In existing technologies, to improve the high-temperature mechanical properties of aluminum alloys at 300℃ and above, high levels of Cu, Ni, or other expensive metallic elements are typically added, significantly increasing material costs. This invention significantly reduces material costs by decreasing the content of expensive Ni and Cu elements, while simultaneously improving the high-temperature mechanical properties of the material by adding trace amounts of La and Fe elements.
[0021] Furthermore, heat treatment is typically required to improve the room temperature and high temperature mechanical properties of aluminum alloys. However, since existing ingot casting generally employs air cooling, a prolonged high-temperature solution treatment is necessary during the heat treatment process, significantly increasing energy consumption and production costs. This invention utilizes rapid water cooling of the ingot, resulting in a higher concentration of solute atoms dissolved in the matrix. During subsequent direct aging treatment, this allows for the precipitation of fine, dispersed phases, thereby improving the material's mechanical properties. Detailed Implementation
[0022] The present invention will be described below through specific embodiments. Those skilled in the art will understand that the specific embodiments below are merely illustrative and do not limit the scope of the invention in any way. Furthermore, in the following embodiments, unless otherwise specified, the reagents and equipment used are commercially available. If specific processing conditions and methods are not explicitly described in the later embodiments, conditions and methods known in the art can be used for processing.
[0023] In one aspect of the invention, a cast aluminum alloy material is provided, comprising, by mass percentage: 11.5-13.5% Si, 1.5-2.5% Mg, 0.4-0.6% Cu, 0.4-0.65% Ni, 0.1-0.3% Mn, 0.05-0.15% rare earth elements, with the balance being Al and unavoidable impurities.
[0024] Understandably, this invention can significantly reduce material costs by reducing the content of expensive Cu and Ni elements. At the same time, the addition of trace rare earth elements can purify the melt, refine the formation of the Mg2Si phase, and improve the high-temperature mechanical properties of the material.
[0025] In some embodiments of the present invention, the cast aluminum alloy material includes Si, with a Si mass percentage of 11.5-13.5%, specifically 11.5%, 12%, 12.5%, 13%, and 13.5%, etc. According to the Al-Si binary phase diagram, the eutectic point is 12.3%. The present invention limits the Si content to 11.5-13.5%, as the alloy exhibits optimal fluidity and casting performance near the eutectic point.
[0026] The cast aluminum alloy material includes Mg, with a Mg mass percentage of 1.5-2.5%, specifically 1.5%, 2%, and 2.5%. Mg can react with Si to form the Mg2Si phase. Specifically, during aging treatment, fine Mg2Si phases can precipitate, significantly improving the room temperature mechanical properties of the material. However, at temperatures exceeding 200℃, the Mg2Si phase tends to coarsen, deteriorating the high-temperature mechanical properties of the material. Therefore, the Mg content should not be too high. When the Mg content is 1.5-2.5%, the resulting cast aluminum alloy material exhibits both good room temperature and high-temperature mechanical properties.
[0027] The cast aluminum alloy material includes Cu, with a Cu mass percentage of 0.4-0.6%, specifically 0.4%, 0.5%, and 0.6%. Cu can react with Al to form the Al₂Cu phase, which begins to coarsen above 250°C, leading to a decrease in high-temperature mechanical properties. Furthermore, Cu can also react with Al, Mg, Si, etc., to form the Al₅Cu₂Mg₈Si₆ phase. This phase exhibits excellent thermal stability at 250°C, but above 300°C, it cannot effectively improve the high-temperature mechanical properties of the material.
[0028] The cast aluminum alloy material includes Ni, with a Ni mass percentage of 0.4-0.65%, specifically 0.4%, 0.5%, 0.65%, etc. The addition of Ni can form a variety of heat-resistant phases, such as Al3Ni, Al3CuNi, Al7Cu4Ni, etc., and these second phases have excellent thermal stability above 300℃.
[0029] The cast aluminum alloy material includes Mn, with a mass percentage of Mn of 0.1-0.3%, specifically 0.1%, 0.2%, and 0.3%. Mn can refine grains and form a thermally stable dispersed phase, improving high-temperature mechanical properties. However, if the amount of Mn added is too high, for example, exceeding 0.3%, it will promote the formation of coarse Al-Mn phases, thereby deteriorating the mechanical properties.
[0030] The cast aluminum alloy material includes rare earth elements, with a mass percentage content of 0.05-0.15%, specifically 0.05%, 0.1%, and 0.15%. The rare earth elements include at least one of La and Ce. Rare earth elements have low solubility in Al and exist as intermetallic compounds, such as AlSiLa, LaSi2, and Al... 11 La3, Al 11 Phases such as Ce3, these intermetallic compounds can effectively improve the mechanical properties of cast aluminum alloys.
[0031] In some embodiments of the present invention, the cast aluminum alloy material further includes Fe, with a mass percentage content of 0.1-0.7%, specifically 0.1%, 0.3%, 0.5%, and 0.7%. Adding inexpensive Fe can improve the high-temperature mechanical properties of the material. Specifically, Fe can form a heat-resistant Al9FeNi phase with Al and Ni elements, which exhibits good thermal stability below 350°C; therefore, the addition of Fe is expected to improve the high-temperature mechanical properties of the aluminum alloy. However, the presence of Fe can also form plate-like or needle-like β-AlFeSi phases and blocky or fishbone-like α-AlFeSi phases. Experimental studies have shown that α-AlFeSi has a smaller deterioration effect on the mechanical properties of the cast aluminum alloy material of the present invention compared to β-AlFeSi. The present invention can effectively suppress the formation of coarse, iron-rich β-AlFeSi phase by adding rare earth elements, thereby effectively improving the high-temperature mechanical properties of the cast aluminum alloy material.
[0032] In another aspect, the present invention provides a method for preparing the above-mentioned cast aluminum alloy material, comprising the following steps: (1) The raw materials are smelted and cast to obtain ingots; (2) The ingot is water-cooled and then aged to obtain cast aluminum alloy material.
[0033] In this invention, the raw materials are first melted and cast to obtain ingots.
[0034] In some embodiments of the present invention, the smelting is carried out in a smelting furnace, and the smelting includes a melting stage performed sequentially. The steps of the melting stage are as follows: pure aluminum ingots, aluminum-silicon master alloys, aluminum-copper master alloys, aluminum-nickel master alloys, and aluminum-manganese master alloys are mixed and melted at 720-740°C; the temperature is further raised to 760-790°C, and aluminum-iron master alloys and aluminum-rare earth element master alloys are added for melting treatment; the temperature is further lowered to 690-700°C, and pure magnesium ingots are added for melting to obtain molten metal liquid.
[0035] In some embodiments of the present invention, in order to lower the melting temperature, Si, Cu, Ni, Mn, Fe, and rare earth elements are all added in the form of master alloys. Specifically, silicon is added in the form of an aluminum-silicon master alloy, for example, Al-20Si; copper is added in the form of an aluminum-copper master alloy, for example, Al-20Cu; nickel is added in the form of an aluminum-nickel master alloy, for example, Al-10Ni; manganese is added in the form of an aluminum-manganese master alloy, for example, Al-10Mn; iron is added in the form of an aluminum-iron master alloy, for example, Al-20Fe; and rare earth elements are added in the form of an aluminum-rare earth element master alloy, for example, Al-90La.
[0036] In some embodiments of the present invention, the smelting further includes a refining stage. The steps of the refining stage are as follows: heating the molten metal to 730-750°C, adding a refining agent, stirring, and then allowing it to stand to obtain a refined liquid. The stirring time is 5-10 minutes, and the standing time is 10-20 minutes. The amount of refining agent added is 0.8-1.2% of the total mass of the molten metal. The present invention does not impose any special limitations on the refining agent; it can be purchased commercially. The refining agent used in the embodiments and comparative examples of the present invention is JDJB aluminum alloy refining agent produced by Zhangjiagang Haohua Light Alloy Materials Co., Ltd.
[0037] In some embodiments of the present invention, the smelting process further includes a refining and homogenizing stage. The steps of the refining and homogenizing stage are as follows: cooling the refined liquid to 720-730°C, adding a refining agent, stirring, and then allowing it to stand to obtain an alloy liquid. The refining agent includes at least one of aluminum-titanium-boron, aluminum-titanium-carbon, and aluminum-titanium-carbon-boron master alloys, for example, Al-5Ti-1B or Al-5Ti-C. The amount of the refining agent added is 0.08-0.12% of the refined liquid, based on the mass percentage of titanium in the refining agent. The stirring time is 5-10 minutes, and the standing time is 10-15 minutes.
[0038] In some embodiments of the present invention, the casting temperature is 190-210°C. The casting involves pouring molten alloy into a metal mold preheated to 190-210°C, allowing it to solidify, and obtaining an ingot. Preferably, to reduce impurities, slag on the surface of the molten alloy is removed before pouring it into the metal mold.
[0039] In this invention, after obtaining the ingot, the ingot is water-cooled and then aged to obtain cast aluminum alloy material.
[0040] In some embodiments of the present invention, the water cooling temperature is 20-40°C, and the time is 8-15 seconds. Specifically, the water cooling is performed under flowing water conditions. Furthermore, experiments have shown that when the water cooling time is too short, problems such as coarse grains and coarsening of precipitates occur; if the water cooling time is too long, the stability of the supersaturated solid solution in the alloy decreases, weakening the subsequent age hardening effect.
[0041] In some embodiments of the present invention, the aging treatment temperature is 225-235℃, specifically 225℃, 230℃, and 235℃, etc., and the holding time is 4-6 hours, specifically 4 hours, 5 hours, and 6 hours, etc. Specifically, for the aging treatment of water-cooled ingots, the ingot is heated to 225-235℃ in the furnace within 1-3 hours, held for 4-6 hours, and then removed for air cooling. In the present invention, if the aging temperature is too low, it will take a long time for the precipitates to fully precipitate, or the precipitates may not precipitate at all; while if the aging temperature is too high, it will easily lead to coarsening of the precipitates.
[0042] To improve the room temperature and high temperature mechanical properties of cast aluminum alloys, heat treatment is usually required. However, since existing technologies generally employ air cooling for ingots, a prolonged high-temperature solution treatment is necessary during the heat treatment process, significantly increasing energy consumption and production costs. This invention uses rapid water cooling of the ingot, resulting in a higher concentration of solute atoms dissolved in the matrix. During the subsequent direct aging process, fine, dispersed phases can precipitate, thus improving the material's mechanical properties.
[0043] In another aspect, the present invention also provides the application of the above-described cast aluminum alloy material or the cast aluminum alloy material prepared by the method described in any one of the above-described methods in an engine piston.
[0044] The technical solutions of this invention will be clearly and completely described below with reference to specific embodiments. The embodiments of this application are only examples, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.
[0045] Example 1 This embodiment provides a cast aluminum alloy material, which, by mass percentage, consists of 12.8% Si, 2.0% Mg, 0.53% Cu, 0.43% Ni, 0.175% Mn, 0.1% La, with the balance being Al and unavoidable impurities.
[0046] The specific steps for preparing this cast aluminum alloy material are as follows: (1) Place pure aluminum ingots, Al-20Si, Al-20Cu, Al-10Ni, and Al-10Mn into a melting furnace and heat to 730°C to completely melt the materials; continue heating to 780°C and add Al-90La intermediate alloy to completely melt the materials; then cool down to 700°C, add pure magnesium ingots, and keep the temperature to completely melt the pure magnesium to obtain molten metal liquid.
[0047] (2) Heat the molten metal to 750°C, add 1% of the total mass fraction of the molten metal as a refining agent, stir for 5 minutes and let stand for 15 minutes to obtain the refining liquid.
[0048] (3) Cool the refining liquid to 730℃, add Al-5Ti-1B refining agent, the refining agent is added at a mass fraction of 0.1% of titanium, after the material melts, stir thoroughly for 5 minutes, let stand and keep warm for 15 minutes, scrape off the slag on the surface with a spoon to obtain the alloy liquid.
[0049] (4) Pour the molten alloy into a metal mold preheated to 200°C for casting to obtain an ingot.
[0050] (5) After the ingot solidifies, it is immediately cooled in flowing water at 25°C for 12 seconds to obtain a water-cooled ingot.
[0051] (6) After water cooling, the ingot is placed in a heat treatment furnace for aging treatment. The furnace is heated to 230°C for 2 hours and then held for 5 hours. The ingot is then taken out and air-cooled to obtain the cast aluminum alloy material.
[0052] Example 2 This embodiment is basically the same as Embodiment 1, except that the mass percentage of nickel in the cast aluminum alloy material is 0.63%.
[0053] Example 3 This embodiment is basically the same as Embodiment 1, except that: the cast aluminum alloy material also contains 0.5% Fe by mass; and during the preparation process, the Fe element is added simultaneously with the Al-90La master alloy in the form of Al-20Fe.
[0054] Example 4 This embodiment is basically the same as Embodiment 2, except that: the cast aluminum alloy material also contains 0.5% Fe by mass; and during the preparation process, the Fe element is added simultaneously with the Al-90La master alloy in the form of Al-20Fe.
[0055] Comparative Example 1 This comparative example is basically the same as Example 1, except that: no aging treatment was performed, that is, step (6) was not performed.
[0056] Comparative Example 2 This comparative example is basically the same as Example 1, except that the rare earth element La was not added.
[0057] Correspondingly, step (1) in the preparation process is as follows: put pure aluminum ingots, Al-20Si, Al-20Cu, Al-10Ni and Al-10Mn into a melting furnace, heat to 730℃ to completely melt the materials; continue to cool to 700℃, add pure magnesium ingots, keep warm to completely melt the pure magnesium, and obtain molten metal liquid.
[0058] Comparative Example 3 This comparative example is basically the same as Example 2, except that the rare earth element La was not added.
[0059] Correspondingly, step (1) in the preparation process is as follows: put pure aluminum ingots, Al-20Si, Al-20Cu, Al-10Ni and Al-10Mn into a melting furnace, heat to 730℃ to completely melt the materials; continue to cool to 700℃, add pure magnesium ingots, keep warm to completely melt the pure magnesium, and obtain molten metal liquid.
[0060] Comparative Example 4 This comparative example is basically the same as Example 1, except that Cu and Ni elements were not added.
[0061] Correspondingly, step (1) in the preparation process is as follows: pure aluminum ingots, Al-20Si and Al-10Mn are placed in a melting furnace and heated to 730°C to completely melt the materials; the temperature is further increased to 780°C and Al-90La intermediate alloy is added to completely melt the materials; then the temperature is lowered to 700°C and pure magnesium ingots are added and kept at the temperature to completely melt the pure magnesium to obtain molten metal liquid.
[0062] Comparative Example 5 This comparative example is basically the same as Comparative Example 4, except that the mass percentage of La in the cast aluminum alloy material is 0.5%.
[0063] Comparative Example 6 This comparative example is basically the same as Comparative Example 4, except that the mass percentage of La in the cast aluminum alloy material is 1.5%.
[0064] Comparative Example 7 This comparative example is basically the same as Example 1, except that the Cu content is 1.05% and no Ni element is added.
[0065] Correspondingly, step (1) in the preparation process is as follows: pure aluminum ingots, Al-20Si, Al-20Cu and Al-10Mn are placed in a melting furnace and heated to 730℃ to completely melt the materials; the temperature is further increased to 780℃ and Al-90La intermediate alloy is added to completely melt the materials; then the temperature is lowered to 700℃ and pure magnesium ingots are added and kept at the temperature to completely melt the pure magnesium to obtain molten metal liquid.
[0066] Comparative Example 8 This comparative example is basically the same as Comparative Example 7, except that the mass percentage of La in the cast aluminum alloy material is 0.5%.
[0067] Comparative Example 9 This comparative example is basically the same as Comparative Example 7, except that the mass percentage of La in the cast aluminum alloy material is 1.5%.
[0068] Comparative Example 10 This comparative example is basically the same as Comparative Example 2, except that the mass percentage of Ni in the cast aluminum alloy material is 0.85%.
[0069] Comparative Example 11 This comparative example is basically the same as Example 1, except that water cooling is replaced with air cooling. That is, steps (5) and (6) are as follows: (5) After the ingot solidifies, it is air-cooled to obtain an air-cooled ingot; (6) After air cooling, the ingot is placed in a heat treatment furnace for aging treatment. The furnace temperature is raised to 230°C for 2 hours and then held for 5 hours. After that, it is taken out and air cooled to obtain cast aluminum alloy material.
[0070] The tensile strength (Rm) and yield strength (Rp0.2) of the cast aluminum alloy materials of Examples 1-4 and Comparative Examples 1-11 were tested at room temperature and 300°C. The results are shown in Table 1.
[0071] Table 1
[0072] Note: The cast aluminum alloy materials of Comparative Examples 4-8 have low room temperature strength, which does not meet the room temperature strength requirements of engine pistons. Therefore, their strength data at 300℃ were not tested.
[0073] As can be seen from Table 1, the cast aluminum alloy material provided by this invention has good room temperature mechanical properties, with a tensile strength of 219-269 MPa and a yield strength of 203-211 MPa. Simultaneously, the material also exhibits good heat resistance, with a tensile strength of 116-131 MPa and a yield strength of 102-116 MPa at 300℃.
[0074] As can be seen from Examples 1-4 and Comparative Examples 1-3 and 11, rapid water cooling followed by direct aging treatment of ingots can significantly improve the mechanical properties of cast aluminum alloys. Furthermore, compared to cast aluminum alloys without rare earth elements, cast aluminum alloys containing trace amounts of rare earth elements exhibit relatively superior high-temperature mechanical properties. Simultaneously, the addition of Fe can further improve the high-temperature mechanical properties of cast aluminum alloys.
[0075] As can be seen from Examples 1-4 and Comparative Examples 4-9, the simultaneous addition of Cu and Ni elements is essential for preparing cast aluminum alloy materials with excellent room temperature and high temperature mechanical properties.
[0076] Comparative Example 10 has a high Ni content (0.85%), thus exhibiting superior high-temperature mechanical properties. However, as can be seen from Examples 1-4 of this invention, the cast aluminum alloy material prepared by this invention, with a lower Ni content, achieves similar or even superior high-temperature mechanical properties to the aluminum alloy material of Comparative Example 10 due to the addition of rare earth elements or rare earth elements and iron. This further demonstrates that, even with a low Ni content, adding appropriate amounts of rare earth elements or rare earth elements and iron can effectively improve the high-temperature mechanical properties of cast aluminum alloy materials.
[0077] Furthermore, the M124 alloy developed by Mahle AG in Germany has a composition of 11-13 wt% Si, 0.8-1.5 wt% Cu, 0.8-1.3 wt% Mg, and 0.8-1.3 wt% Ni. This alloy has a higher content of Cu and Ni elements, and its room temperature tensile strength is 200-250 MPa, and its yield strength is 190-230 MPa; its tensile strength at 250°C is 90-110 MPa, and its yield strength is 70-100 MPa; and its tensile strength at 350°C is 35-55 MPa, and its yield strength is 20-30 MPa. It is evident that using the composition and preparation process of this patent can achieve superior room temperature and high temperature mechanical properties.
[0078] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.
Claims
1. A method for preparing a cast aluminum alloy material, characterized in that, Includes the following steps: (1) The raw materials are smelted and cast to obtain ingots; The raw materials, by mass percentage, include: Si 11.5-13.5%, Mg 1.5-2.5%, Cu 0.4-0.6%, Ni 0.4-0.65%, Mn 0.1-0.3%, Fe 0.1-0.7%, rare earth elements 0.05-0.15%, with the balance being Al and unavoidable impurities. The rare earth elements include at least one of La and Ce. (2) The ingot is water-cooled and then aged to obtain cast aluminum alloy material; The water cooling temperature is 20-40℃, and the time is 8-15 seconds; The aging treatment temperature is 225-235℃, and the holding time is 4-6 hours.
2. The method for preparing cast aluminum alloy material according to claim 1, characterized in that, The smelting process includes a melting stage and a refining stage performed sequentially. The melting stage involves the following steps: pure aluminum ingots, aluminum-silicon master alloy, aluminum-copper master alloy, aluminum-nickel master alloy, and aluminum-manganese master alloy are mixed and melted at 720-740℃; the temperature is further increased to 760-790℃, and aluminum-iron master alloy and aluminum-rare earth element master alloy are added for melting treatment; the temperature is further decreased to 690-700℃, and pure magnesium ingots are added for melting to obtain molten metal liquid; The refining stage involves the following steps: heating the molten metal to 730-750°C, adding 0.8-1.2% of the total mass of the molten metal as a refining agent, stirring, and allowing it to stand to obtain a refined liquid.
3. The method for preparing cast aluminum alloy material according to claim 2, characterized in that, The smelting process also includes a refining and homogenizing stage; The steps of the refining and homogenizing stage are as follows: cool the refining liquid to 720-730℃, add a refining agent, stir and let stand to obtain an alloy liquid; The amount of the refining agent added is 0.08-0.12% of the refining liquid by mass percentage of titanium.
4. The method for preparing cast aluminum alloy material according to claim 3, characterized in that, The refining agent includes at least one of aluminum-titanium-boron, aluminum-titanium-carbon, and aluminum-titanium-carbon-boron master alloys.
5. The method for preparing cast aluminum alloy material according to claim 1, characterized in that, The casting temperature is 190-210℃.
6. The application of a cast aluminum alloy material prepared by the method of any one of claims 1-5 in an engine piston.