A grain refiner, a preparation method thereof and a grain refinement method of ADC12 aluminum alloy

Abstract

The present application relates to the technical field of aluminum alloy casting, in particular to a grain refiner, a preparation method thereof and a grain refinement method of ADC12 aluminum alloy.The grain refiner is composed of the following elements in mass percentage: 2.5-3.5% Ti, 0.5-1.5% B, 0.4-0.8% Sc, and the balance of Al, and the total mass percentage of the elements is 100%.The grain refiner effectively solves the problem of "silicon poisoning" of conventional refiners in high-silicon aluminum alloy (especially ADC12 aluminum alloy) through the synergistic effect of Ti, B and Sc, and the grain refinement rate is as high as 41%, which is significantly better than the effect of the existing Al-Ti-B refiner in high-silicon aluminum alloy.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy casting technology, specifically to a grain refiner and its preparation method, and a method for refining the grains of ADC12 aluminum alloy. Background Technology

[0002] Aluminum is widely distributed in the Earth's crust, ranking third after oxygen and silicon. It has low density, high specific strength, excellent electrical and thermal conductivity, and is easy to cast and recycle. It has found widespread application in high-tech fields such as machinery, automotive, aerospace, and military industries. To obtain aluminum alloys with excellent comprehensive properties, grain refinement is one of the important means to improve the quality of aluminum materials and to obtain optimal as-cast grains. Therefore, the development of effective grain refiners has become an important area of ​​research in aluminum alloy materials.

[0003] The most commonly used grain refiner for cast aluminum alloys is Al-Ti-B. Al-Ti-B can effectively refine the microstructure of the alloy, but Ti may react with Si, a phenomenon known as "silicon poisoning" of the grain refiner, leading to a weakening or failure of the refining effect. ADC12 aluminum alloy has a silicon mass fraction of 9.6%~12%, which is relatively high and directly affects the performance of the aluminum alloy.

[0004] Adding trace amounts of Sc to aluminum alloys produces Al3Sc, a homogeneous nucleated coherent precipitate with small size, high density, and uniform distribution, which effectively refines the grain size. Furthermore, Sc can effectively suppress the recrystallization temperature of aluminum alloys, improving their overall performance. However, directly adding Sc is quite expensive, making it difficult to meet the economic requirements of large-scale industrial production, thus limiting the application of Sc in grain refinement of high-silicon aluminum alloys.

[0005] To address the issues of "silicon poisoning" when using conventional Al-Ti-B grain refiners on high-silicon aluminum alloys and the high cost of directly adding Sc, there is an urgent need to develop a grain refiner that is compatible with high-silicon aluminum alloys, provides stable grain refinement, and has controllable costs, along with its preparation and application methods. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies, such as the tendency of conventional Al-Ti-B grain refiners to cause "silicon poisoning" in high-silicon aluminum alloys and the high cost of directly adding Sc elements. This invention provides a grain refiner suitable for high-silicon aluminum alloys, along with a method for preparing the grain refiner and its application in ADC12 aluminum alloys, to achieve effective grain refinement of high-silicon aluminum alloys, improve their microstructure and properties, and also take into account production economy.

[0007] To achieve the above objectives, in a first aspect, the present invention provides a grain refiner, which is composed of the following elements in mass percentage: 2.5~3.5% Ti, 0.8~1.2% B, 0.4~0.8% Sc, with the balance being Al, and the total mass percentage of each element being 100%.

[0008] Preferably, the grain refiner contains 2.8-3.3% Ti and 0.8-1.2% B by mass.

[0009] Preferably, the grain refiner is suitable for high-silicon aluminum alloys with a silicon mass fraction of 8-15%.

[0010] More preferably, the grain refiner is suitable for high-silicon aluminum alloys with a silicon mass fraction of 9-12%.

[0011] More preferably, the grain refiner is suitable for ADC12 aluminum alloy.

[0012] Secondly, the present invention provides a method for preparing a grain refiner as described herein, the method comprising: 1) Heat and melt the aluminum material, remove the slag, and obtain molten aluminum; 2) The titanium source and boron source are mixed and added to the aluminum liquid described in step 1) to carry out the first reaction to remove fluoride; 3) Place Al The Sc alloy is added to the aluminum alloy melt that has been defluorinated in step 2) to carry out a second reaction, refine and remove impurities, and obtain an alloy melt with grain refiner; 4) Preheat the mold, pour the alloy melt from step 3) into the mold, cool and demold to obtain a grain refiner ingot.

[0013] Preferably, in step 1), the aluminum material is industrial pure aluminum with a purity > 99.7%.

[0014] Preferably, in step 1), the heating and melting conditions include a temperature of 750~800℃.

[0015] Preferably, in step 1), the slag removal includes: cooling the aluminum material to 700~740℃ after it is completely melted, removing the oxide slag from the surface of the molten aluminum, raising the temperature of the molten aluminum to 750~800℃, and holding it for 20~30 minutes; and removing the slag from the surface of the molten aluminum.

[0016] Preferably, in step 2), the titanium source is selected from one or more of potassium fluorotitanate, titanium powder, titanium tetrachloride, and titanium dioxide.

[0017] Preferably, in step 2), the boron source is selected from one or more of potassium fluoroborate, borax, and boric acid.

[0018] Preferably, in step 2), based on the weight of the grain refiner, the mass percentage of Ti element is 2.5~3.5wt%, preferably 2.8~3.3%; and the mass percentage of B element is 0.5~1.5wt%, preferably 0.8~1.2%.

[0019] Preferably, in step 2), the conditions for the first reaction include: a stirring rate of 50-80 rpm, a time of 20-40 min, and a temperature of 750-800 °C.

[0020] Preferably, in step 2), the method for removing fluoride includes: first removing fluoride salts from the surface of the molten aluminum, and then, at a temperature of 750-800°C, adding alumina powder accounting for 0.4-0.8% of the mass fraction of the molten aluminum and calcium fluoride accounting for 0.2-0.4% of the mass fraction of the molten aluminum, so that the temperature of the molten aluminum drops to 720-740°C, holding it at that temperature for 10-15 minutes, and then removing fluoride salts from the surface of the molten aluminum again.

[0021] Preferably, in step 3), the Al Sc alloy is Al 10Sc alloy.

[0022] Preferably, in step 3), the mass percentage of Sc element is 0.4~0.8% based on the weight of the grain refiner.

[0023] Preferably, in step 3), the conditions for the second reaction include: a temperature of 720~740℃, a time of 10~15min, stirring once every 4~6min; reducing the temperature of the aluminum alloy melt to 700~710℃, holding for 10~15min, and removing the slag from the surface of the aluminum alloy melt.

[0024] Preferably, in step 3), the refining and impurity removal method includes: refining the aluminum alloy melt with argon gas for 10-15 minutes and cleaning the surface slag.

[0025] Preferably, in step 4), the preheating conditions of the mold include a temperature of 180~200℃.

[0026] Preferably, the preparation method further includes: hot extruding the obtained grain refiner ingot into a bar with a diameter of 5-15 mm.

[0027] Preferably, the ingot is kept at 400~450℃ for 1~2 hours before hot extrusion, the hot extrusion temperature is 420~460℃, and the extrusion ratio is 10~20:1.

[0028] Thirdly, the present invention provides an application of the grain refiner as described in the present invention in cast aluminum alloys, wherein the aluminum alloy is an Al-Si-Cu alloy and the mass fraction of silicon is 8-15%, preferably 9-12%.

[0029] Preferably, the Al-Si-Cu alloy is an ADC12 aluminum alloy.

[0030] Fourthly, the present invention provides a method for grain refinement of ADC12 aluminum alloy, the grain refinement method comprising: heating and holding the ADC12 aluminum alloy at a certain temperature, adding a grain refiner, refining the grains, casting, and cooling to obtain a cast aluminum alloy; wherein, The grain refiner is the grain refiner described in this invention.

[0031] Preferably, the mass ratio of the grain refiner to the ADC12 aluminum alloy is 0.03~0.06:1.

[0032] Preferably, the heating and heat preservation conditions include: a temperature of 720~740℃ and a heat preservation time of 10~15min.

[0033] Preferably, the conditions for grain refinement include: a time of 10-15 minutes, with stirring every 2-3 minutes.

[0034] Preferably, the casting conditions include: a temperature of 680~700℃, and preheating the mold to 180~200℃ before casting.

[0035] In the above technical solution, the grain refiner of the present invention effectively solves the problem of "silicon poisoning" of conventional grain refiners in high silicon aluminum alloys (especially ADC12 aluminum alloys) through the synergistic effect of Ti, B and Sc elements. The grain refinement rate is as high as 41%, which is significantly better than the effect of existing Al-Ti-B grain refiners in high silicon aluminum alloys.

[0036] Furthermore, after applying the grain refiner of this invention, the tensile strength, elongation, yield strength and Brinell hardness of ADC12 aluminum alloy are comprehensively improved, and the overall mechanical properties are significantly improved, which can better meet the requirements of industrial applications for material performance.

[0037] Furthermore, the grain refiner of this invention uses an Al-10Sc alloy to introduce Sc element, avoiding the high cost of directly adding Sc element; at the same time, the addition amounts of Ti, B and Sc elements are all controlled within a low range, further reducing production costs and making it suitable for large-scale industrial production.

[0038] Furthermore, the preparation method of the grain refiner of the present invention and its application method in ADC12 aluminum alloy are simple to operate, the process parameters are easy to control, no special or complex equipment is required, and it is convenient for industrial promotion and application.

[0039] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0040] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings: Figure 1 This is a morphology diagram of the grain refiner obtained in Example 1 of the present invention; Figure 2 This is a morphology diagram of the grain refiner obtained in Example 2 of the present invention; Figure 3 This is a morphology diagram of the grain refiner prepared in Example 3 of the present invention. Detailed Implementation

[0041] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0042] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0043] In a first aspect, the present invention provides a grain refiner, which is composed of the following elements in mass percentage: 2.5~3.5% Ti, 0.5~1.5% B, 0.4~0.8% Sc, with the balance being Al, and the total mass percentage of each element is 100%.

[0044] The grain refiner of this invention addresses the "silicon poisoning" problem in high-silicon aluminum alloys by introducing and optimizing the ratio of Ti, B, and Sc elements, utilizing their synergistic effect. Specifically, Sc preferentially reacts with free Si elements (excluding eutectic silicon) in the high-silicon aluminum alloy to form an Al-Si-Sc ternary phase, reducing the reaction between Si and Ti elements and preventing Ti deactivation. Simultaneously, Sc and Ti synergistically form Al3(Sc,Ti) heterogeneous nucleation particles. The nucleation efficiency of Al3(Sc,Ti) nucleation particles is higher than that of single Al3Ti or Al3Sc phases, resulting in more effective grain refinement. Furthermore, the formation of TiB2 / Al3(Sc,Ti) clusters increases the viscosity of the aluminum melt to disperse TiB2, reducing TiB2 agglomeration. Additionally, the specific surface area of ​​Al3Ti decreases, improving high-temperature stability, ultimately achieving effective grain refinement of the high-silicon aluminum alloy.

[0045] In this invention, the grain refiner contains 2.8-3.3% Ti by mass and 0.8-1.2% B by mass.

[0046] In this invention, the grain refiner is suitable for high-silicon aluminum alloys, wherein the mass fraction of silicon in the high-silicon aluminum alloy is 8-15%, preferably 9-12%; more preferably ADC12 aluminum alloy.

[0047] The grain refiner of the present invention can specifically solve the problem of conventional grain refiner failure caused by the high silicon content of ADC12 aluminum alloy, and significantly improve the mechanical properties of ADC12 aluminum alloy.

[0048] Secondly, the present invention provides a method for preparing a grain refiner as described herein, the method comprising: 1) Heat and melt the aluminum material, remove the slag, and obtain molten aluminum; 2) The titanium source and boron source are mixed and added to the aluminum liquid described in step 1) to carry out the first reaction to remove fluoride; 3) Place Al The Sc alloy is added to the aluminum alloy melt that has been defluorinated in step 2) to carry out a second reaction, refine and remove impurities, and obtain an alloy melt with grain refiner; 4) Preheat the mold, pour the alloy melt from step 3) into the mold, cool and demold to obtain a grain refiner ingot.

[0049] In step 1) of this invention, the aluminum material is industrial pure aluminum with a purity > 99.7%.

[0050] In step 1) of this invention, the heating and melting conditions include a temperature of 750~800℃.

[0051] In step 1) of this invention, the slag removal includes: after the aluminum material is completely melted, cooling it to 700-740°C, removing the oxide slag from the surface of the molten aluminum, raising the temperature of the molten aluminum to 750-800°C, and holding it at that temperature for 20-30 minutes; and removing the slag from the surface of the molten aluminum. The slag removal operation is performed after the aluminum material is completely melted, and its purpose is to remove the oxide slag from the surface of the molten aluminum to ensure the purity of the molten aluminum.

[0052] In step 2) of this invention, the titanium source is selected from one or more of potassium fluorotitanate, titanium powder, titanium tetrachloride and titanium dioxide; preferably potassium fluorotitanate.

[0053] In step 2) of this invention, the boron source is selected from one or more of potassium fluoroborate, borax and boric acid; preferably potassium fluoroborate.

[0054] In step 2) of this invention, the mass percentage of Ti is 2.5~3.5wt% and the mass percentage of B is 0.5~1.5wt%, based on the weight of the grain refiner.

[0055] In step 2) of the present invention, the conditions for the first reaction include: a stirring rate of 50-80 rpm, a time of 20-40 min, and a temperature of 750-800℃.

[0056] In step 2) of this invention, the method for removing fluoride includes: first removing fluoride salts from the surface of the molten aluminum, and then, at a temperature of 750-800°C, adding alumina powder accounting for 0.4-0.8% of the mass fraction of the molten aluminum and calcium fluoride accounting for 0.2-0.4% of the mass fraction of the molten aluminum, so that the temperature of the molten aluminum drops to 720-740°C, and holding it at that temperature for 10-15 minutes, and then removing fluoride salts from the surface of the molten aluminum again.

[0057] In step 3) of the present invention, the Al Sc alloy is Al The 10Sc alloy introduces Sc element through Al-10Sc master alloy, which can reduce the cost of directly adding Sc element, while ensuring that Sc element is uniformly distributed in the melt; based on the weight of grain refiner, the mass percentage of Sc element is 0.4~0.8%.

[0058] In step 3) of the present invention, the conditions for the second reaction include: a temperature of 720~740℃, a time of 10~15min, stirring once every 4~6min; reducing the temperature of the aluminum alloy melt to 700~710℃, holding it at that temperature for 10~15min, and removing the slag from the surface of the aluminum alloy melt.

[0059] In step 3) of this invention, the refining and impurity removal operation adopts a conventional aluminum alloy refining method. The purpose is to remove gases and impurities from the alloy melt and ensure the purity of the grain refiner. The refining and impurity removal method includes: refining the aluminum alloy melt with argon gas for 10-15 minutes and cleaning the surface slag.

[0060] In step 4) of this invention, the preheating conditions of the mold include a temperature of 180℃~200℃.

[0061] For ease of use, this invention requires further processing. The grain refiner ingot can be hot-extruded into rods with a diameter of 5-15 mm. Before hot extrusion, the ingot needs to be held at 400-450℃ for 1-2 hours. The hot extrusion temperature is 420-460℃, and the extrusion ratio is 10-20:1. After extrusion, the rods are air-cooled to room temperature, straightened, and cut to length to obtain the finished rods. The rod shape facilitates subsequent addition and dispersion in molten aluminum alloy.

[0062] Thirdly, the present invention provides an application of the grain refiner as described in the present invention in cast aluminum alloys, wherein the aluminum alloy is an Al-Si-Cu alloy, and the mass fraction of silicon element is 8~15%, preferably 9~12%; more preferably, the Al-Si-Cu alloy is an ADC12 aluminum alloy.

[0063] Fourthly, the present invention provides a method for grain refinement of ADC12 aluminum alloy, the grain refinement method comprising: heating and holding the ADC12 aluminum alloy at a certain temperature, adding a grain refiner, refining the grains, casting, and cooling to obtain a cast aluminum alloy; wherein, The grain refiner is the grain refiner described in this invention.

[0064] The grain refinement method for ADC12 aluminum alloy of the present invention can effectively refine the grains of ADC12 aluminum alloy, with a grain refinement rate of 33% to 41%, while significantly improving its mechanical properties. Compared with ADC12 aluminum alloy raw material without the addition of this grain refiner, the tensile strength of the cast ADC12 aluminum alloy increases from 190 MPa to 235 to 258 MPa, the elongation increases from 1.54% to 2.42% to 2.51%, the yield strength increases from 110 MPa to 116 to 125 MPa, and the Brinell hardness increases from 78 HBW to 88 to 97 HBW.

[0065] In this invention, the mass ratio of the grain refiner to the ADC12 aluminum alloy is 0.03~0.06:1, that is, the grain refiner addition ratio is 3~6% of the mass of the ADC12 aluminum alloy material, preferably 4%.

[0066] The heating and heat preservation conditions described in this invention include: a temperature of 720~740℃ and a heat preservation time of 10~15min.

[0067] The grain refinement conditions described in this invention include: a time of 10-15 minutes, stirring once every 2-3 minutes, preferably once every 3 minutes, to ensure that the grain refiner and the ADC12 aluminum alloy liquid are fully in contact and react.

[0068] The casting conditions described in this invention include: a temperature of 680~700℃, and preheating the mold to 180~200℃ before casting.

[0069] In this invention, the room temperature is 15-30°C.

[0070] The present invention will be described in detail below through examples. In the following examples, the pharmaceuticals and agents are all conventional commercially available products.

[0071] Example 1 (1) Weigh 14.5 kg of potassium fluorotitanate (K2TiF6), 9.6 kg of potassium fluoroborate (KBF4), 5.2 kg of Al-10Sc alloy and 100 kg of industrial pure aluminum (purity > 99.7%) respectively. Crush the Al-10Sc alloy into particles with a particle size of 1~3 mm using a crusher, and dry it at 120℃ for 1 hour before use.

[0072] (2) Add 100kg of industrial pure aluminum to the smelting furnace, heat it to 780℃ to melt it completely, cool it down to 720℃ and remove the slag for the first time; heat it up to 780℃ to refine and degas it, keep it at this temperature for 25min, remove the slag for the second time, and obtain the aluminum liquid; (3) Mix the potassium fluorotitanate and potassium fluoroborate weighed in step (1) evenly, add them to the aluminum liquid obtained in step (2), stir at a rate of 60 rpm, and react at a temperature of 780℃ for 30 min; after the reaction is completed, first remove the fluoride salts on the alloy surface, then add alumina powder accounting for 0.6% of the mass fraction of aluminum liquid and calcium fluoride powder accounting for 0.3% of the mass fraction of aluminum liquid, continue stirring for 2 min, refine and degas, cool the aluminum liquid to 730℃, keep it at the temperature for 10 min, and obtain the aluminum alloy melt after removing the slag; (4) Add the crushed Al-10Sc alloy particles from step (1) to the aluminum alloy melt obtained in step (3). After it is fully melted, stir it every 5 minutes and keep it at 730°C for 10 minutes. After the heat preservation is completed, use argon gas to refine the aluminum alloy melt for 15 minutes to remove impurities and remove surface slag, and obtain the grain refiner alloy melt. (5) Preheat the mold to 190°C, pour the alloy melt from step (4) into the mold, and demold after solidification and cooling to obtain a grain refiner ingot; keep the ingot at 400°C for 1 hour, and then hot extrude it at 435°C with an extrusion ratio of 16:1 to produce a bar with a diameter of 8 mm, which is the required grain refiner, denoted as B1, and its morphology is shown in the figure. Figure 1 As shown.

[0073] Depend on Figure 1 It can be seen that the grain refiner prepared in this embodiment has a uniform structure and no obvious impurities or agglomeration.

[0074] Example 2 (1) Weigh 15.5kg K2TiF6, 12.0kg KBF4, 6.3kg Al-10Sc alloy and 101kg industrial pure aluminum (purity > 99.7%) respectively. Crush the Al-10Sc alloy into particles with a particle size of 1~3mm using a crusher, and dry it at 120℃ for 1h before use.

[0075] (2) Add 101 kg of industrial pure aluminum to the smelting furnace, heat it to 750°C to melt it completely, cool it down to 700°C and remove the slag for the first time; heat it up to 750°C to refine and degas it, keep it at this temperature for 25 min, remove the slag for the second time, and obtain the aluminum liquid. (3) Mix the K2TiF6 and KBF4 weighed in step (1) evenly, add them to the aluminum liquid obtained in step (2), stir at a rate of 50 rpm, and react at a temperature of 750℃ for 20 min; after the reaction is completed, first remove the fluoride salts on the alloy surface, then add alumina powder accounting for 0.4% of the mass fraction of aluminum liquid and calcium fluoride powder accounting for 0.2% of the mass fraction of aluminum liquid, continue stirring for 2 min, refine and degas, cool the aluminum liquid to 720℃, keep it at the temperature for 15 min, and obtain the aluminum alloy melt after removing the slag; (4) Add the crushed Al-10Sc alloy particles from step (1) to the aluminum alloy melt obtained in step (3). After it is fully melted, stir it every 4 minutes and keep it at 720°C for 15 minutes. After the heat preservation is completed, use argon gas to refine the aluminum alloy melt for 10 minutes to remove impurities and remove surface slag, and obtain the grain refiner alloy melt. (5) Preheat the mold to 180°C, pour the above alloy melt into the mold, and demold after solidification and cooling to obtain a grain refiner ingot; keep the ingot at 400°C for 1 hour, and then hot extrude it at 435°C with an extrusion ratio of 16:1 to produce a bar with a diameter of 8 mm, which is the required grain refiner, denoted as B2, and its morphology is shown in the figure. Figure 2 As shown.

[0076] Depend on Figure 2 It can be seen that the grain refiner prepared in this embodiment has a uniform particle distribution and a dense structure.

[0077] Example 3 (1) Weigh 16.6kg K2TiF6, 13.2kg KBF4, 8.4kg Al-10Sc alloy and 100kg industrial pure aluminum (purity > 99.7%) respectively. Crush the Al-10Sc alloy into particles with a particle size of 1~3mm using a crusher, and dry it at 120℃ for 1h before use.

[0078] (2) Add 100 kg of industrial pure aluminum to the smelting furnace, heat it to 800°C to melt it completely, cool it down to 740°C and remove the slag for the first time; heat it up to 800°C to refine and degas it, keep it at this temperature for 25 min, remove the slag for the second time, and obtain the aluminum liquid. (3) Mix the K2TiF6 and KBF4 weighed in step (1) evenly, add them to the aluminum liquid obtained in step (2), stir at a speed of 80 rpm, and react at a temperature of 800℃ for 40 min; after the reaction is completed, first remove the fluoride salts on the alloy surface, then add alumina powder accounting for 0.8% of the mass fraction of aluminum liquid and calcium fluoride powder accounting for 0.4% of the mass fraction of aluminum liquid, continue stirring for 2 min, refine and degas, cool the aluminum liquid to 740℃, keep it at the temperature for 15 min, and obtain the aluminum alloy melt after removing the slag; (4) Add the crushed Al-10Sc alloy particles from step (1) to the aluminum alloy melt obtained in step (3). After it is fully melted, stir it every 6 minutes and keep it at 740°C for 15 minutes. After the heat preservation is completed, use argon gas to refine the aluminum alloy melt for 15 minutes to remove impurities and remove surface slag, and obtain the grain refiner alloy melt. (5) Preheat the mold to 200°C, pour the above alloy melt into the mold, and demold after solidification and cooling to obtain a grain refiner ingot; keep the ingot at 400°C for 1 hour, and then hot extrude it at 435°C with an extrusion ratio of 16:1 to produce a bar with a diameter of 8 mm, which is the required grain refiner, denoted as B3, and its morphology diagram is as follows. Figure 3 As shown.

[0079] Depend on Figure 3 It can be seen that the nucleation core particles in the grain refiner prepared in this embodiment are small and uniformly dispersed, which is beneficial to the subsequent grain refinement of aluminum alloy.

[0080] The mass fractions of each element in the grain refiners prepared in Examples 1-3 are shown in Table 1.

[0081] Table 1

[0082] Comparative Example 1 The process was carried out in accordance with Example 2, except that “6.3 kg Al-10Sc alloy” in step (1) was replaced with “12.6 kg Al-5Sc intermediate alloy” (with the same Sc content), and other conditions remained unchanged, and a grain refiner was obtained, which was denoted as D1.

[0083] Comparative Example 2 The process was carried out in accordance with Example 2, except that “6.3 kg Al-10Sc alloy” in step (1) was replaced with “18.56 kg Al-10Sc intermediate alloy” (the Sc mass fraction in the grain refiner was 1.5%), and other conditions remained unchanged, and the grain refiner was obtained and denoted as D2.

[0084] Application Example 1 The ADC12 aluminum alloy raw material liquid was heated to 730℃ and held for 12 minutes. Grain refiners prepared in Examples 1-3 and Comparative Examples 1-2 were added at a mass ratio of 4% of the ADC12 aluminum alloy raw material liquid. The mixture was stirred to disperse it evenly and subjected to grain refinement treatment for 15 minutes, with stirring every 3 minutes. The ADC12 aluminum alloy liquid was then refined and impurity removed by argon gas for 15 minutes to remove surface slag. After the treatment was completed, the temperature was lowered to 680℃. The mold was preheated to 180℃, and the refined and impurity removed ADC12 aluminum alloy liquid was poured into the mold and cooled to room temperature to obtain ADC12 aluminum alloy.

[0085] Detection Example 1 The mechanical properties of the ADC12 aluminum alloy and the ADC12 aluminum alloy raw material prepared in accordance with Example 1 were tested, and the results are shown in Table 2.

[0086] Table 2

[0087] As can be seen from the test results in Table 2, the grain refiner of the present invention has a significant effect on improving the mechanical properties of ADC12 aluminum alloy.

[0088] The tensile strength of ADC12 aluminum alloy raw material without the grain refiner of this invention is only 190 MPa. After adding the grain refiner of this invention, the tensile strength of the cast ADC12 aluminum alloy is significantly improved. Specifically, the tensile strength of ADC12 aluminum alloy with the grain refiner of Example 1 of this invention reaches 235 MPa, an increase of 23.7% compared to the raw material; the tensile strength of ADC12 aluminum alloy with the grain refiner of Example 2 of this invention reaches 247 MPa, an increase of 30.0% compared to the raw material; and the tensile strength of ADC12 aluminum alloy with the grain refiner of Example 3 of this invention reaches 258 MPa, an increase of 35.8% compared to the raw material. As the content of Ti, B, and Sc elements in the grain refiner is appropriately increased within the range defined by this invention, the tensile strength shows a gradual upward trend, indicating that the optimization of the element ratio can further enhance the tensile properties of the aluminum alloy. The tensile strength of the ADC12 aluminum alloy cast using the grain refiner obtained by replacing Al-10Sc with Al-5Sc master alloy in Comparative Example 1 was 238 MPa, slightly lower than that of the ADC12 aluminum alloy with the grain refiner added in Example 2 of this invention. This indicates that using Al-10Sc master alloy is more effective than Al-5Sc in exerting the grain refining effect of Sc element, thereby improving the strength of the alloy. In Comparative Example 2, the Sc content of the grain refiner was too high, resulting in a tensile strength of 262 MPa for the cast ADC12 aluminum alloy. Although this was higher than the tensile strength of the ADC12 aluminum alloy with the grain refiner added in Example 2 of this invention, its elongation was significantly reduced.

[0089] The elongation of ADC12 aluminum alloy raw material without the grain refiner of this invention is only 1.54%, indicating poor plasticity. After adding the grain refiner of this invention, the elongation of the cast ADC12 aluminum alloy is significantly improved. The elongation of the ADC12 aluminum alloy with the grain refiner of Example 1 of this invention increased to 2.42%, an increase of 57.1% compared to the raw material; the elongation of the ADC12 aluminum alloy with the grain refiner of Example 2 of this invention increased to 2.46%, an increase of 59.7% compared to the raw material; and the elongation of the ADC12 aluminum alloy with the grain refiner of Example 3 of this invention increased to 2.51%, an increase of 63.0% compared to the raw material. This significant increase in elongation indicates that the plasticity of ADC12 aluminum alloy is significantly improved after treatment with the grain refiner of this invention. It is less prone to brittle fracture under stress and has better toughness, expanding its application in mechanical parts, automotive structural components, and other scenarios requiring high plasticity. The elongation of the ADC12 aluminum alloy with the grain refiner of Comparative Example 1 was 2.09%, significantly lower than that of the ADC12 aluminum alloy with the grain refiner of Example 1 of this invention. This indicates that the grain refinement effect of Sc in the Al-5Sc master alloy is not as good as that of Al-10Sc, resulting in insufficient improvement in alloy plasticity. The elongation of the ADC12 aluminum alloy with the grain refiner of Comparative Example 2 was only 2.03%, the lowest among all samples with added grain refiners, and significantly lower than that of the ADC12 aluminum alloys with the grain refiners of Examples 1-3 of this invention. This shows that a higher Sc content is not necessarily better. When the Sc content is too high, coarse primary Al3Sc phases will precipitate in the melt. These coarse, hard, and brittle phases are irregularly distributed at the grain boundaries, disrupting the continuity of the aluminum matrix and becoming crack initiation points under stress, severely deteriorating the plasticity and toughness of the alloy. Therefore, controlling the Sc content within the range of 0.4-0.8% is key to achieving a balance between grain refinement and plasticity.

[0090] The yield strength of the ADC12 aluminum alloy raw material without the grain refiner of this invention is 110 MPa. After adding the grain refiner of this invention, the yield strength of the cast ADC12 aluminum alloy shows a steady increasing trend. The yield strength of the ADC12 aluminum alloy with the grain refiner of Example 1 reaches 116 MPa, an increase of 5.5% compared to the raw material; the yield strength of the ADC12 aluminum alloy with the grain refiner of Example 2 reaches 121 MPa, an increase of 10.0%; and the yield strength of the ADC12 aluminum alloy with the grain refiner of Example 3 reaches 125 MPa, an increase of 13.6%. The increase in yield strength means that the aluminum alloy has enhanced resistance to permanent deformation and higher structural stability. The yield strength of the ADC12 aluminum alloy with the grain refiner of Comparative Example 1 was 117 MPa, slightly lower than that of the ADC12 aluminum alloy with the grain refiner of Example 2. The yield strength of the ADC12 aluminum alloy with the grain refiner of Comparative Example 1 was 127 MPa, slightly higher than that of the ADC12 aluminum alloy with the grain refiner of Example 2. However, as mentioned above, this strength improvement was achieved at the expense of plasticity. For practical engineering applications, an excessively high Sc content leads to a sharp deterioration in plasticity, making it difficult to meet the requirements of structural materials for comprehensive mechanical properties.

[0091] The Brinell hardness of the ADC12 aluminum alloy raw material without the grain refiner of this invention is only 78 HBW. After adding the grain refiner of this invention, the hardness of the cast ADC12 aluminum alloy is significantly improved. The Brinell hardness of the ADC12 aluminum alloy with the grain refiner of Example 1 of this invention reaches 88 HBW, an increase of 12.8% compared to the raw material; the Brinell hardness of the ADC12 aluminum alloy with the grain refiner of Example 2 of this invention reaches 94 HBW, an increase of 20.5%; and the Brinell hardness of the ADC12 aluminum alloy with the grain refiner of Example 2 of this invention reaches 97 HBW, an increase of 24.4%. The increase in hardness indicates enhanced wear resistance and scratch resistance of the aluminum alloy, which can extend the service life of the finished product, especially suitable for parts requiring surface hardness. The Brinell hardness of the ADC12 aluminum alloy with the grain refiner of Comparative Example 1 is 87 HBW, lower than that of the ADC12 aluminum alloy with the grain refiner of Example 2, further demonstrating the superiority of Al-10Sc master alloy over Al-5Sc. The Brinell hardness of the ADC12 aluminum alloy with the addition of the grain refiner of Comparative Example 2 is 99 HBW, which is higher than that of the ADC12 aluminum alloy with the addition of the grain refiner of Example 2. However, the deterioration of its elongation greatly reduces the engineering value of this hardness improvement.

[0092] As can be seen from the data in Table 2, the ADC12 aluminum alloys with added grain refiners from Examples 1-3 of this invention show significant improvements in tensile strength, elongation, yield strength, and Brinell hardness compared to the raw ADC12 aluminum alloy. Furthermore, all performance indicators are superior to those of the ADC12 aluminum alloys with added grain refiners from Comparative Examples 1-2. It is particularly noteworthy that while the ADC12 aluminum alloy with added grain refiner from Comparative Example 2 has slightly higher strength indicators than the ADC12 aluminum alloy with added grain refiners from the examples, its elongation is severely degraded, failing to meet the basic requirements for plasticity and toughness in practical applications. Conversely, the ADC12 aluminum alloy with added grain refiner from Comparative Example 1 has lower performance indicators than the ADC12 aluminum alloy with added grain refiner from Example 2, verifying the superiority of the Al-10Sc master alloy in terms of Sc element introduction efficiency, refinement effect, and overall mechanical property improvement.

[0093] The above results fully demonstrate that the present invention, through the synergistic effect of Ti, B, and Sc, forms Al3(Sc,Ti) heterogeneous nucleation particles, inhibits TiB2 clusters, and reduces the "silicon poisoning" effect in high-silicon aluminum alloys. This not only solves the technical problem of easy failure of conventional Al-Ti-B refining agents in high-silicon aluminum alloys, but also achieves comprehensive optimization of the overall mechanical properties of ADC12 aluminum alloy.

[0094] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0095] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0096] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A grain refiner, characterized in that, The grain refiner is composed of the following elements by mass percentage: 2.5~3.5% Ti, 0.5~1.5% B, 0.4~0.8% Sc, with the balance being Al, and the total mass percentage of each element is 100%.

2. The grain refiner according to claim 1, characterized in that, The grain refiner contains 2.8-3.3% Ti and 0.8-1.2% B by mass; and / or, The grain refiner is suitable for high-silicon aluminum alloys with a silicon mass fraction of 8-15%; and / or, The grain refiner is suitable for high-silicon aluminum alloys with a silicon mass fraction of 9-12%; and / or, The grain refiner is suitable for ADC12 aluminum alloy.

3. A method for preparing a grain refiner as described in claim 1 or 2, characterized in that, The preparation method includes: 1) Heat and melt the aluminum material, remove the slag, and obtain molten aluminum; 2) The titanium source and boron source are mixed and added to the aluminum liquid described in step 1) to carry out the first reaction to remove fluoride; 3) Place Al The Sc alloy is added to the aluminum alloy melt that has been defluorinated in step 2) to carry out a second reaction, refine and remove impurities, and obtain an alloy melt with grain refiner; 4) Preheat the mold, pour the alloy melt from step 3) into the mold, cool and demold to obtain a grain refiner ingot.

4. The preparation method according to claim 3, characterized in that, In step 1), the aluminum material is industrial pure aluminum with a purity > 99.7%; The heating and melting temperature is 750~800℃; The slag removal process includes: after the aluminum material is completely melted, cooling it to 700~740℃, removing the oxide slag from the surface of the molten aluminum, raising the temperature of the molten aluminum to 750~800℃, and holding it at that temperature for 20~30 minutes; and removing the slag from the surface of the molten aluminum.

5. The preparation method according to claim 3 or 4, characterized in that, In step 2), the titanium source is selected from one or more of potassium fluorotitanate, titanium powder, titanium tetrachloride, and titanium dioxide; The boron source is selected from one or more of potassium fluoroborate, borax, and boric acid; Based on the weight of the grain refiner, the mass percentage of Ti is 2.5~3.5 wt%, and the mass percentage of B is 0.5~1.5 wt%; and / or, Based on the weight of the grain refiner, the mass percentage of Ti is 2.8~3.3% and the mass percentage of B is 0.8~1.2%.

6. The preparation method according to claim 3, characterized in that, In step 2), the conditions for the first reaction include: a stirring rate of 50-80 rpm, a time of 20-40 min, and a temperature of 750-800℃; The method for removing fluoride includes: first removing fluoride salts from the surface of the molten aluminum; then, at a temperature of 750-800°C, adding alumina powder at a mass fraction of 0.4-0.8% and calcium fluoride at a mass fraction of 0.2-0.4% to lower the temperature of the molten aluminum to 720-740°C, holding the temperature for 10-15 minutes, and then removing fluoride salts from the surface of the molten aluminum again.

7. The preparation method according to claim 3, characterized in that, In step 3), the Al Sc alloy is Al 10Sc alloy; Based on the weight of the grain refiner, the mass percentage of Sc element is 0.4~0.8%; The conditions for the second reaction include: a temperature of 720~740℃, a time of 10~15min, and stirring every 4~6min; reducing the temperature of the aluminum alloy melt to 700~710℃, holding it at that temperature for 10~15min, and removing the slag from the surface of the aluminum alloy melt. The refining and impurity removal method includes: refining the aluminum alloy melt with argon gas for 10-15 minutes and cleaning the surface slag.

8. The preparation method according to claim 3, characterized in that, In step 4), the preheating conditions for the mold include: a temperature of 180~200℃; and / or, The preparation method further includes: hot extruding the obtained grain refiner ingot into a rod with a diameter of 5-15 mm; Before hot extrusion, the ingot is kept at 400~450℃ for 1~2 hours, the hot extrusion temperature is 420~460℃, and the extrusion ratio is 10~20:

1.

9. The application of a grain refiner as described in claim 1 or 2 in cast aluminum alloys, characterized in that, The aluminum alloy is an Al-Si-Cu alloy with a silicon content of 8-15% by mass; and / or, The aluminum alloy is an Al-Si-Cu alloy with a silicon content of 9-12% by mass; and / or, The Al-Si-Cu alloy is ADC12 aluminum alloy.

10. A method for grain refinement of ADC12 aluminum alloy, characterized in that, The grain refinement method includes: heating and holding the ADC12 aluminum alloy at a certain temperature, adding a grain refiner to refine the grains, casting, and cooling to obtain a cast aluminum alloy; wherein... The grain refiner is the grain refiner according to claim 1 or 2; and / or, The grain refiner to ADC12 aluminum alloy has a mass ratio of 0.03~0.06:1; and / or, The heating and heat preservation conditions include: a temperature of 720~740℃ and a heat preservation time of 10~15min; The conditions for grain refinement include: a time of 10-15 minutes, with stirring every 2-3 minutes; The casting conditions include: a temperature of 680~700℃, and preheating the mold to 180~200℃ before casting.

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