Method for preparing hypereutectic aluminum-silicon alloy semi-solid slurry by utilizing ultrasonic vibration

Abstract

The invention belongs to the technical field of hypereutectic aluminum-silicon alloy material preparation, and discloses a method for preparing hypereutectic aluminum-silicon alloy semi-solid slurry by ultrasonic vibration, which comprises the following steps: melting a ZL109 aluminum alloy, adding an Al-30Si intermediate alloy, heating to 800-810 DEG C, keeping the temperature for 15-20 minutes, and adding a refining agent into the melt for refining; after refining is completed, the melt is cooled to 740-750 DEG C, an alterant is added, and heat preservation is conducted for 15-20 min; and after heat preservation is finished, the melt is cooled to 580-600 DEG C, ultrasonic vibration stirring is conducted on the melt, the ultrasonic power ranges from 500 W to 1500 W, the ultrasonic time ranges from 3 min to 10 min, the melt is cast into a mold after ultrasonic vibration, and the hypereutectic aluminum-silicon alloy semi-solid slurry is obtained. According to the method, primary silicon can be effectively and remarkably refined, the structure distribution is uniform, the mechanical properties such as the tensile strength and the stretch rate of the material are improved, the internal quality of a casting is improved, the bearing capacity, the fracture resistance and the toughness of the casting are improved, the structural stability of a product is enhanced, and the mechanical properties and the use reliability of the casting are guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of hypereutectic aluminum-silicon alloy materials, and in particular relates to a method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry by utilizing ultrasonic vibration. Background Art

[0002] Hypereutectic aluminum-silicon alloys are widely used in engine pistons due to their high specific strength, low density, low thermal expansion coefficient, and good volume stability. However, during the squeeze casting process of hypereutectic aluminum-silicon alloys, coarse and uneven silicon phases appear, and sharp corners cause stress concentration, which both reduce the mechanical properties of hypereutectic aluminum-silicon alloys.

[0003] There have been attempts in the existing technology to prepare semi-solid slurry through metamorphic treatment, but there are still certain deficiencies in terms of the degree of refinement of primary silicon crystals, uniformity of tissue distribution, and mechanical properties of semi-solid slurry. It cannot meet the high requirements of engine pistons for casting load-bearing capacity, fracture resistance, ductility, etc. Summary of the Invention

[0004] In order to solve some or all of the technical problems existing in the above-mentioned prior art, the present invention provides a method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration, a hypereutectic aluminum-silicon alloy material prepared by the method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration, the hypereutectic aluminum-silicon alloy material in the hypereutectic aluminum-silicon alloy material, and a method for reducing the primary silicon size and matrix grain size in the hypereutectic aluminum-silicon alloy material by implementing the method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration.

[0005] In a first aspect of the present invention, a method for preparing a semi-solid slurry of a hypereutectic aluminum-silicon alloy using ultrasonic vibration is provided, comprising the following steps:

[0006] After melting the ZL109 aluminum alloy, add the Al-30Si master alloy, heat it to 800-810℃ and keep it for 15-20 minutes, then add the refining agent to the melt for refining;

[0007] After refining, cool the melt to 740-750℃, add the modifier, and keep it warm for 15-20 minutes;

[0008] After the insulation is completed, the melt is cooled to 580-600°C and subjected to ultrasonic vibration stirring. The ultrasonic power is controlled to be 500-1500W, and the ultrasonic vibration implementation time is controlled to be 3-10 minutes. After the ultrasonic vibration, the melt is cast into a mold to obtain a hypereutectic aluminum-silicon alloy semi-solid slurry.

[0009] Furthermore, in the above method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration, the mass ratio of the ZL109 aluminum alloy to the Al-30Si master alloy is controlled to be (4.9-5.1):1.

[0010] Furthermore, in the above method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration, the melting temperature of the ZL109 aluminum alloy is set to 580-610°C.

[0011] Furthermore, in the above method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration, the refining agent is a potassium-free refining agent, and the amount of the refining agent added is (0.3-0.4)% of the sum of the mass of the ZL109 aluminum alloy and the Al-30Si master alloy.

[0012] Furthermore, in the above-mentioned method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration, the modifiers are Al-4.5P modified alloy and Al-10Sr modified alloy, and the mass ratio of Al-4.5P modified alloy to Al-10Sr modified alloy is controlled to be (2-2.5):1. When adding the modifier, Al-10Sr modified alloy is added first, and then Al-4.5P modified alloy is added. The total amount of modifier added is (0.9-1.0)% of the sum of the mass of ZL109 aluminum alloy and Al-30Si master alloy.

[0013] Furthermore, in the above-mentioned method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration, the Al-30Si master alloy is polished and preheated at 200°C for 2 hours before being added to the ZL109 aluminum alloy melt; the probe of the ultrasonic vibration device is preheated in a heating furnace at 580-600°C for 25-35 minutes before ultrasonic vibration stirring; and the mold is preheated to 300°C before the melt is cast into the mold.

[0014] Furthermore, in the above-mentioned method of preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration, the prepared hypereutectic aluminum-silicon alloy semi-solid slurry includes, by mass percentage, Si: 14.0-16.0%, Cu: 0.4-1.3%, Mg: 0.6-1.1%, Ni: 0.6-1.3%, P: 0.03-0.033%, Sr: 0.03-0.033%, and the balance Al, and the impurity content is <1%.

[0015] In a second aspect of the present invention, a hypereutectic aluminum-silicon alloy material is provided. The hypereutectic aluminum-silicon alloy material is prepared by the above-mentioned method of preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration, wherein the hypereutectic aluminum-silicon alloy material includes, by mass percentage, Si: 14.0-16.0%, Cu: 0.4-1.3%, Mg: 0.6-1.1%, Ni: 0.6-1.3%, P: 0.03-0.033%, Sr: 0.03-0.033%, and the balance Al, and the impurity content is <1%.

[0016] In a third aspect of the present invention, there is provided application of the aforementioned hypereutectic aluminum-silicon alloy material in automobile pistons.

[0017] In a fourth aspect of the present invention, a method for refining the primary silicon size and matrix grain size in a hypereutectic aluminum-silicon alloy material is provided, which is achieved by implementing the above-mentioned method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration.

[0018] The method of the present invention for preparing a semi-solid slurry of a hypereutectic aluminum-silicon alloy by using ultrasonic vibration has the following advantages and beneficial effects: it can effectively and significantly refine the primary silicon crystal, and make the microstructure evenly distributed, and the mechanical properties of the material such as tensile strength and elongation are significantly improved. Therefore, in the subsequent solidification process of the semi-solid slurry of the hypereutectic aluminum-silicon alloy extrusion casting, due to the fine grains and uniform microstructure, its solidification shrinkage is relatively uniform, which can effectively reduce the formation of concentrated shrinkage cavities. At the same time, the fine grains also make the shrinkage feeding channels between the dendrites more unobstructed, reducing the possibility of shrinkage defects. This helps to improve the internal quality of the casting, improve the bearing capacity, fracture resistance and toughness of the casting, reduce the occurrence of cracks, enhance the structural stability of the product, and ensure the mechanical properties and reliability of the casting. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without inventive work. In the drawings:

[0020] Figure 1 This is a microstructure diagram of the hypereutectic aluminum-silicon alloy semi-solid slurry obtained by the method for preparing the hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration in Example 1 of the present invention.

[0021] Figure 2 This is a microstructure diagram of the hypereutectic aluminum-silicon alloy semi-solid slurry obtained by the method for preparing the hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration in Example 2 of the present invention.

[0022] Figure 3 This is a microstructure diagram of the hypereutectic aluminum-silicon alloy semi-solid slurry obtained by the method for preparing the hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration in Example 3 of the present invention.

[0023] Figure 4 This is a microstructure diagram of the hypereutectic aluminum-silicon alloy semi-solid slurry obtained by the method for preparing the hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration in Example 4 of the present invention.

[0024] Figure 5 This is a microstructure diagram of the hypereutectic aluminum-silicon alloy semi-solid slurry obtained by the method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration in Example 5 of the present invention.

[0025] Figure 6 This is the microstructure diagram of the hypereutectic aluminum-silicon alloy semi-solid slurry obtained in Comparative Example 1. DETAILED DESCRIPTION

[0026] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] The method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration provided by the present invention comprises the following steps:

[0028] After melting the ZL109 aluminum alloy, add the Al-30Si master alloy, heat it to 800-810℃ and keep it for 15-20 minutes, then add the refining agent to the melt for refining;

[0029] After refining, cool the melt to 740-750℃, add the modifier, and keep it warm for 15-20 minutes;

[0030] After the insulation is completed, the melt is cooled to 580-600°C and subjected to ultrasonic vibration stirring. The ultrasonic power is controlled to be 500-1500W, and the ultrasonic vibration implementation time is controlled to be 3-10 minutes. After the ultrasonic vibration, the melt is cast into a mold to obtain a hypereutectic aluminum-silicon alloy semi-solid slurry.

[0031] In the method of the present invention for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration, the main reasons for selecting the Al-30Si master alloy are that the Al-30Si master alloy is inexpensive, does not easily float in the aluminum alloy melt, and is easy to add; furthermore, the Al-30Si master alloy block has good wettability with the ZL109 aluminum alloy melt, and therefore does not easily agglomerate in the ZL109 aluminum alloy melt and can be evenly distributed in a short time; furthermore, the Al-30Si master alloy has high thermal stability.

[0032] In the method of preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration of the present invention, the probe of the ultrasonic vibration device is preheated in a heating furnace at 580-600°C for 25-35 minutes before ultrasonic vibration stirring. The purpose of preheating the probe is: (1) by preheating the probe, thermal stress damage can be prevented, and problems such as cracks and deformation of instrument components caused by thermal stress can be avoided, which seriously affect the service life and performance of the instrument; (2) by preheating the probe, the temperature difference between the probe and the high-temperature melt can be reduced, ensuring the ultrasonic propagation effect, optimizing the acoustic performance, and improving the processing efficiency and quality. Preferably, the probe of the ultrasonic vibration device is selected to be a titanium alloy probe.

[0033] In the method of the present invention for preparing a semi-solid slurry of hypereutectic aluminum-silicon alloy using ultrasonic vibration, the melt is first cooled to 580-600°C before being cast into a mold. The purpose is to ensure that the melt is cast and formed near the liquidus line of the molten metal. Since the alloy elements are more easily evenly distributed in the liquid phase, the segregation of the alloy elements in the molten metal can be reduced.

[0034] In the method of preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration of the present invention, the mold is preheated to 300°C before the melt is cast into the mold. The purpose of mold preheating is: (1) by preheating the mold, the temperature difference between the mold and the high-temperature melt can be reduced, reducing thermal fatigue stress, preventing the mold from expanding and cracking due to rapid heating, and extending the service life of the mold; (2) by preheating the mold, the melt will not cool rapidly after being poured into the mold, thereby maintaining its plasticity, reducing deformation resistance, and ensuring the quality of the casting. Preferably, the mold material is selected from hot work die steel 3Cr2W8V.

[0035] Furthermore, in the above-mentioned method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration, the melting temperature of the ZL109 aluminum alloy is set to 580-610°C, Al-30Si master alloy is added to the ZL109 aluminum alloy melt, and the temperature is raised to 800-810°C and kept warm for 15-20 minutes. A refining agent is added to the melt for refining. After slag removal, the temperature is lowered to 740-750°C, a modifier is added, and the melt is kept warm for 15-20 minutes after the modifier is added.

[0036] Furthermore, in the above method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration, the Al-30Si master alloy is polished and preheated at 200° C. for 2 h before being added to the ZL109 aluminum alloy melt.

[0037] Furthermore, in the above method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration, the mass ratio of the ZL109 aluminum alloy to the Al-30Si master alloy is controlled to be (4.9-5.1):1.

[0038] Furthermore, in the above method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration, the refining agent is a potassium-free refining agent, and the amount of the refining agent added is (0.3-0.4)% of the sum of the mass of the ZL109 aluminum alloy and the Al-30Si master alloy.

[0039] Furthermore, in the above method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration, the modifiers are Al-4.5P modified alloy and Al-10Sr modified alloy, and the amount of the modifier added is (0.8-1.1)% of the sum of the mass of the ZL109 aluminum alloy and the Al-30Si master alloy.

[0040] As a specific embodiment, the mass ratio of Al-4.5P modified alloy and Al-10Sr modified alloy in the modifier is controlled to be (2-2.5):1. When adding the modifier, Al-10Sr modified alloy is added first, and then Al-4.5P modified alloy is added. The total amount of modifier added is (0.9-1.0)% of the sum of the mass of ZL109 aluminum alloy and Al-30Si master alloy.

[0041] In the method of preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration, an Al-4.5P and an Al-10Sr alloy are selected as modifiers in a mass ratio of (2-2.5):1. When adding the modifiers, the Al-10Sr alloy is added first, followed by the Al-4.5P alloy. Sr is first added to refine the eutectic silicon through poisoning, and then a sufficient amount of P is added to form AlP. The Sr reacts with the generated AlP to form Sr3P2, and the remaining AlP serves as heterogeneous nucleation for primary silicon crystals to refine the primary silicon crystals. Furthermore, by controlling the amount of modifier added to (0.9-1.0)% of the combined mass of the ZL109 aluminum alloy and the Al-30Si master alloy, sufficient P can be ensured to refine the primary silicon crystals. Adding a modifier less than or greater than the aforementioned (0.9-1.0)% will weaken the refinement effect, resulting in increased grain size.

[0042] In the method of the present invention for preparing a semi-solid slurry of a hypereutectic aluminum-silicon alloy using ultrasonic vibration, Al-4.5P metamorphic alloy and Al-10Sr metamorphic alloy are selected as modifiers because Al-4.5P metamorphic alloy and Al-10Sr metamorphic alloy are inexpensive and easy to prepare. In addition, it has been verified in practice that using Al-4.5P metamorphic alloy and Al-10Sr metamorphic alloy as modifiers has a significant effect on refining primary silicon crystals, which can greatly optimize the microstructure of the hypereutectic aluminum-silicon alloy.

[0043] In the method of the present invention for preparing a semi-solid slurry of a hypereutectic aluminum-silicon alloy by utilizing ultrasonic vibration, the ultrasonic parameters during the ultrasonic vibration stirring of the melt are set as follows: ultrasonic power 500-1500W, ultrasonic temperature 580-600°C, and ultrasonic time 3-10min. The reason for selecting the above ultrasonic parameters in the present invention is that: when the ultrasonic parameters are lower than the above range, (1) the ultrasonic power is too low, the ultrasonic vibration has insufficient effect on grain refinement, and the grains cannot be fully shattered; (2) the ultrasonic temperature is too low, the melt has poor fluidity, and the ultrasonic vibration is insufficient to overcome the high viscosity of the melt, resulting in uneven distribution of alloy components. ; (3) The ultrasonic time is too short, and the ultrasonic vibration does not have enough time to refine the grains, and the grain refinement process cannot be fully stimulated, resulting in larger grain size; For the case where the ultrasonic parameters are higher than the above range, (1) The ultrasonic power is too high, which may cause the gas to precipitate too quickly and form a large number of bubbles; (2) The ultrasonic temperature is too high, which may inhibit the effect of ultrasonic vibration on grain refinement and even cause grain coarsening and reduce the mechanical properties of the material; (3) The ultrasonic time is too long. Since ultrasonic vibration treatment has a certain upper limit on its effect, after a certain time, continuing vibration may no longer significantly improve the treatment effect and may even produce negative effects.

[0044] Furthermore, in the above-mentioned method of preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration, the prepared hypereutectic aluminum-silicon alloy semi-solid slurry includes, by mass percentage, Si: 14.0-16.0%, Cu: 0.4-1.3%, Mg: 0.6-1.1%, Ni: 0.6-1.3%, P: 0.03-0.033%, Sr: 0.03-0.033%, and the balance Al, and the impurity content is <1%.

[0045] As another embodiment of the present invention, a hypereutectic aluminum-silicon alloy material is also provided. The hypereutectic aluminum-silicon alloy material is prepared by the above-mentioned method of preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration, wherein the hypereutectic aluminum-silicon alloy material includes, by mass percentage, Si: 14.0-16.0%, Cu: 0.4-1.3%, Mg: 0.6-1.1%, Ni: 0.6-1.3%, P: 0.03-0.033%, Sr: 0.03-0.033%, and the remainder Al, and the impurity content is <1%.

[0046] As another embodiment of the present invention, there is also provided the use of the above-mentioned hypereutectic aluminum-silicon alloy material in automobile pistons.

[0047] As another embodiment of the present invention, a method for refining the primary silicon size and matrix grain size in a hypereutectic aluminum-silicon alloy material is also provided, which is achieved by implementing the above-mentioned method of preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration.

[0048] The following is a further detailed description of the method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration in conjunction with specific embodiments of the present invention and comparative examples of the prior art. In the following embodiments and comparative examples, unless otherwise specified, all raw materials used can be obtained from commercial sources, wherein:

[0049] The ZL109 aluminum alloy used in the embodiments and comparative examples comprises, by mass percentage, Si: 11.0-13.0%, Cu: 0.5-1.5%, Mg: 0.8-1.3%, Ni: 0.8-1.5%, and the balance Al, with an impurity content of <1.2%;

[0050] The Al-30Si master alloy used in the examples and comparative examples comprises, by mass percentage, Si: 29.0-31.0%, Cu: 0.01-0.03%, Mg: 0.02-0.04%, Mn: 0.02-0.04%, Zn: 0.01-0.03%, Ti: 0.05-0.01%, and the balance Al;

[0051] The Al-4.5P modified alloy used in the examples and comparative examples comprises, by mass percentage, P: 4.5-5%, Cu: 0.01-0.03%, Mg: 0.02-0.04%, and the balance Al;

[0052] The Al-10Sr modified alloy used in the examples and comparative examples comprises, by mass percentage, 10-11% Sr, 0.01-0.03% Cu, 0.02-0.04% Mg, and the balance Al.

[0053] Example 1

[0054] The method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration according to Example 1 of the present invention includes:

[0055] Step 1: Preheat the Al-30Si master alloy at 200°C for 2 hours, and then place the crucible in a resistance furnace and preheat it to 400°C.

[0056] Step 2: Place 500g of ZL109 aluminum alloy in a crucible, heat to 700℃ and melt it completely. After skimming off the slag, add 100g of Al-30Si master alloy and heat to 800℃ and melt it completely. After holding it for 15 minutes, add 2g of potassium-free refining agent to refine the melt and hold it for 15 minutes. After skimming off the slag, cool it to 750℃, then add 1.8g of Al-10Sr modified alloy and hold it for 10 minutes, then add 4g of Al 4.5P modified alloy and hold it for 10 minutes.

[0057] Step 3: Cool the melt to 590°C, extend the probe of the ultrasonic vibration device preheated to 590°C into 30 mm below the melt to perform ultrasonic vibration stirring on the melt. The ultrasonic frequency is 20.1 Hz, the ultrasonic power is 1500 W, and the ultrasonic time is 5 minutes. After the ultrasonic vibration stirring is completed, the melt is cast into a mold made of 3Cr2W8V material preheated to 300°C to obtain a hypereutectic aluminum-silicon alloy semi-solid slurry.

[0058] The hypereutectic aluminum-silicon alloy semi-solid slurry prepared in Example 1 includes, by mass percentage, Si: 15%, Cu: 0.9%, Mg: 0.8%, Ni: 0.9%, P: 0.03%, Sr: 0.03%, and the balance Al, and the impurity content is <1%.

[0059] Example 2

[0060] The method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration according to embodiment 2 of the present invention includes:

[0061] Step 1: Preheat the Al-30Si master alloy at 200°C for 2 hours, and then place the crucible in a resistance furnace and preheat it to 400°C.

[0062] Step 2: Place 490g of ZL109 aluminum alloy in a crucible, heat to 700℃ and melt it completely. After skimming off the slag, add 100g of Al-30Si master alloy and heat to 800℃ and melt it completely. After holding it for 15 minutes, add 2g of potassium-free refining agent to refine the melt and hold it for 15 minutes. After skimming off the slag, cool it to 750℃, then add 1.6g of Al-10Sr modified alloy and hold it for 10 minutes, then add 4g of Al 4.5P modified alloy and hold it for 10 minutes.

[0063] Step 3: Cool the melt to 600°C, extend the probe of the ultrasonic vibration device preheated to 600°C into 30 mm below the melt to perform ultrasonic vibration stirring on the melt. The ultrasonic frequency is 20.1 Hz, the ultrasonic power is 500 W, and the ultrasonic time is 5 minutes. After the ultrasonic vibration stirring is completed, the melt is cast into a mold made of 3Cr2W8V material preheated to 300°C to obtain a hypereutectic aluminum-silicon alloy semi-solid slurry.

[0064] The hypereutectic aluminum-silicon alloy semi-solid slurry prepared in Example 2 includes Si: 15%, Cu: 0.9%, Mg: 0.8%, Ni: 0.9%, and the balance Al in terms of mass percentage, and the impurity content is <1%.

[0065] Example 3

[0066] The method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration according to Example 3 of the present invention includes:

[0067] Step 1: Preheat the Al-30Si master alloy at 200°C for 2 hours, and then place the crucible in a resistance furnace and preheat it to 400°C.

[0068] Step 2: Place 500g of ZL109 aluminum alloy in a crucible, heat to 700℃ and melt it completely. After skimming off the slag, add 100g of Al-30Si master alloy and heat to 800℃ and melt it completely. After holding it for 15 minutes, add 2g of potassium-free refining agent to refine the melt and hold it for 15 minutes. After skimming off the slag, cool it to 750℃, then add 1.8g of Al-10Sr modified alloy and hold it for 10 minutes, then add 4g of Al 4.5P modified alloy and hold it for 10 minutes.

[0069] Step 3: Cool the melt to 590°C, extend the probe of the ultrasonic vibration device preheated to 590°C into 30 mm below the melt to perform ultrasonic vibration stirring on the melt. The ultrasonic frequency is 20.1 Hz, the ultrasonic power is 1000 W, and the ultrasonic time is 5 minutes. After the ultrasonic vibration stirring is completed, the melt is cast into a mold made of 3Cr2W8V material preheated to 300°C to obtain a hypereutectic aluminum-silicon alloy semi-solid slurry.

[0070] The hypereutectic aluminum-silicon alloy semi-solid slurry prepared in Example 3 includes, by mass percentage, Si: 15%, Cu: 0.9%, Mg: 0.8%, Ni: 0.9%, P: 0.03%, and the balance Al, and the impurity content is <1%.

[0071] Example 4

[0072] The method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration according to Example 4 of the present invention includes:

[0073] Step 1: Preheat the Al-30Si master alloy at 200°C for 2 hours, and then place the crucible in a resistance furnace and preheat it to 400°C.

[0074] Step 2: Place 500g of ZL109 aluminum alloy in a crucible, heat to 700℃ and melt it completely. After skimming off the slag, add 100g of Al-30Si master alloy and heat to 800℃ and melt it completely. After holding it for 15 minutes, add 2g of potassium-free refining agent to refine the melt and hold it for 15 minutes. After skimming off the slag, cool it to 750℃, then add 1.8g of Al-10Sr modified alloy and hold it for 10 minutes, then add 4g of Al 4.5P modified alloy and hold it for 10 minutes.

[0075] Step 3: Cool the melt to 590°C, extend the probe of the ultrasonic vibration device preheated to 590°C into 30 mm below the melt to perform ultrasonic vibration stirring on the melt. The ultrasonic frequency is 20.1 Hz, the ultrasonic power is 1500 W, and the ultrasonic time is 3 minutes. After the ultrasonic vibration stirring is completed, the melt is cast into a mold made of 3Cr2W8V material preheated to 300°C to obtain a hypereutectic aluminum-silicon alloy semi-solid slurry.

[0076] The hypereutectic aluminum-silicon alloy semi-solid slurry prepared in Example 4 includes, by mass percentage, Si: 15%, Cu: 0.9%, Mg: 0.8%, Ni: 0.9%, Sr: 0.03%, and the balance Al, and the impurity content is <1%.

[0077] Example 5

[0078] The method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration according to Example 5 of the present invention includes:

[0079] Step 1: Preheat the Al-30Si master alloy at 200°C for 2 hours, and then place the crucible in a resistance furnace and preheat it to 400°C.

[0080] Step 2: Place 510g of ZL109 aluminum alloy in a crucible, heat to 700℃ and melt it completely. After skimming off the slag, add 100g of Al-30Si master alloy and heat to 800℃ and melt it completely. After holding it for 15 minutes, add 2g of potassium-free refining agent to refine the melt and hold it for 15 minutes. After skimming off the slag, cool it to 750℃, then add 2g of Al-10Sr modified alloy and hold it for 10 minutes, then add 4g of Al 4.5P modified alloy and hold it for 10 minutes.

[0081] Step 3: Cool the melt to 580°C, extend the probe of the ultrasonic vibration device preheated to 580°C into 30 mm below the melt to perform ultrasonic vibration stirring on the melt. The ultrasonic frequency is 20.1 Hz, the ultrasonic power is 1500 W, and the ultrasonic time is 10 min. After the ultrasonic vibration stirring is completed, the melt is cast into a mold made of 3Cr2W8V material preheated to 300°C to obtain a hypereutectic aluminum-silicon alloy semi-solid slurry.

[0082] The hypereutectic aluminum-silicon alloy semi-solid slurry prepared in Example 5 includes, by mass percentage, Si: 15%, Cu: 0.9%, Mg: 0.8%, Ni: 0.9%, Sr: 0.03%, and the balance Al, and the impurity content is <1%.

[0083] Comparative Example 1

[0084] The method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry of Comparative Example 1 comprises:

[0085] Step 1: Preheat the Al30Si master alloy at 200°C for 2 hours, and then place the crucible in a resistance furnace and preheat it to 400°C.

[0086] Step 2: Place 500g of ZL109 aluminum alloy in a crucible, heat it to 700℃ and melt it completely. After skimming off the slag, add 100g of Al-30Si master alloy, heat it to 800℃ and melt it completely. After keeping it warm for 15 minutes, add 2g of potassium-free refining agent to refine the melt, keep it warm for 15 minutes, skim off the slag and cool it to 750℃. Then, add 1.8g of Al-10Sr modified alloy and keep it warm for 10 minutes, then add 4g of Al-4.5P modified alloy and keep it warm for 10 minutes. After cooling the melt to 590℃, cast it into a mold made of 3Cr2W8V material preheated to 300℃ to obtain a hypereutectic aluminum-silicon alloy semi-solid slurry.

[0087] The hypereutectic aluminum-silicon alloy slurry prepared in Comparative Example 1 includes, by mass percentage, Si: 15%, Cu: 0.9%, Mg: 0.8%, Ni: 0.9%, P: 0.03%, Sr: 0.03%, and the balance Al, and the impurity content is <1%.

[0088] The mechanical properties of the hypereutectic aluminum-silicon alloy materials prepared in Examples 1 to 5 of the present invention and Comparative Example 1 were tested according to the GB / T 10623-2008 standard. The specific test results are shown in Table 1:

[0089] Table 1 Mechanical properties of hypereutectic aluminum-silicon alloy materials prepared in Examples 1 to 5 and Comparative Example 1

[0090] Tensile strength σb(Mpa) Elongation δ(%) Example 1 224.75 1.34 Example 2 200.32 1.04 Example 3 216.88 1.13 Example 4 197.07 1.06 Example 5 211.86 1.19 Comparative Example 1 191.28 0.98

[0091] The average grain size of the hypereutectic aluminum-silicon alloy materials prepared in Examples 1 to 5 of the present invention and Comparative Example 1 was tested, and the specific test results are shown in Table 2:

[0092] Table 2 Average grain size of hypereutectic aluminum-silicon alloy materials prepared in Examples 1 to 5 and Comparative Example 1

[0093] Primary silicon crystal (μm) Eutectic silicon (μm) Example 1 15.98 15.18 Example 2 21.52 18.01 Example 3 18.21 17.23 Example 4 18.15 17.15 Example 5 16.11 15.78 Comparative Example 1 24.18 25.78

[0094] In addition, the microstructures of the hypereutectic aluminum-silicon alloy materials prepared in Examples 1 to 5 of the present invention and Comparative Example 1 were tested. Figures 1 to 5 The microstructure diagrams of the hypereutectic aluminum-silicon alloy semi-solid slurries obtained by the method for preparing the hypereutectic aluminum-silicon alloy semi-solid slurry by using ultrasonic vibration according to Examples 1 to 5 of the present invention are respectively shown; Figure 6 The microstructure of the hypereutectic aluminum-silicon alloy semi-solid slurry obtained in Comparative Example 1 is shown.

[0095] By comparing the microstructure, mechanical properties and average grain size of the hypereutectic aluminum-silicon alloy materials prepared in Examples 1 to 5 of the present invention and Comparative Example 1, it can be clearly seen that the structure of the hypereutectic aluminum-silicon alloy material prepared by the method of preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration of the present invention has undergone significant refinement and uniformity, the sizes of primary silicon and eutectic silicon in its structure are greatly reduced, the primary silicon has no sharp edges, and the tensile strength and elongation are significantly improved; while the structure of the hypereutectic aluminum-silicon alloy material prepared in Comparative Example 1 using the prior art still contains large-sized primary silicon and eutectic silicon, and the grain size is uneven, and its mechanical properties are correspondingly low.

[0096] In summary, the method of the present invention for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration adopts the technical measures of first performing a metamorphic treatment and then implementing ultrasonic vibration to prepare the semi-solid slurry. Ultrasonic vibration breaks and refines the coarse and sharp primary silicon phase through cavitation effect and mechanical force to form uniform and fine silicon particles, thereby preventing stress concentration, reducing the cutting effect on the matrix, and improving toughness and ductility. In addition, the ultrasonic vibration stirring action makes the tissue components evenly distributed, reduces segregation, and improves mechanical properties and consistency.

[0097] Therefore, compared with the prior art, the method of the present invention for preparing a semi-solid slurry of hypereutectic aluminum-silicon alloy using ultrasonic vibration has the following advantages and beneficial effects: it can effectively and significantly refine the primary silicon crystal, and make the microstructure evenly distributed, and the mechanical properties of the material such as tensile strength and elongation are significantly improved. Therefore, in the subsequent solidification process of the semi-solid slurry of hypereutectic aluminum-silicon alloy extrusion casting, due to the fine grains and uniform microstructure, its solidification shrinkage is relatively uniform, which can effectively reduce the formation of concentrated shrinkage cavities. At the same time, the fine grains also make the shrinkage feeding channels between dendrites more unobstructed, reducing the possibility of shrinkage defects. This helps to improve the internal quality of the casting, improve the bearing capacity, fracture resistance and toughness of the casting, reduce the occurrence of cracks, enhance the structural stability of the product, and ensure the mechanical properties and reliability of the casting.

[0098] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0099] It should be noted that, in this article, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0100] It should also be noted that, for the numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the range are also included in the present invention.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for preparing a semi-solid slurry of hypereutectic aluminum-silicon alloy using ultrasonic vibration, characterized in that: The following steps are involved: After melting the ZL109 aluminum alloy, add the Al-30Si master alloy, heat it to 800-810℃ and keep it for 15-20 minutes, then add the refining agent to the melt for refining; After refining, cool the melt to 740-750℃, add the modifier, and keep it warm for 15-20 minutes; After the insulation is completed, the melt is cooled to 580-600°C and subjected to ultrasonic vibration stirring. The ultrasonic power is controlled to be 500-1500W, and the ultrasonic vibration implementation time is controlled to be 3-10 minutes. After the ultrasonic vibration, the melt is cast into a mold to obtain a hypereutectic aluminum-silicon alloy semi-solid slurry.

2. The method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration according to claim 1, characterized in that: The mass ratio of ZL109 aluminum alloy to Al-30Si master alloy is controlled at (4.9~5.1):

1.

3. The method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration according to claim 1, characterized in that: The melting temperature of ZL109 aluminum alloy is set to 580-610°C.

4. The method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration according to claim 1, characterized in that: The refining agent is a potassium-free refining agent, and the amount of the refining agent added is (0.3-0.4)% of the sum of the mass of the ZL109 aluminum alloy and the Al-30Si master alloy.

5. The method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration according to claim 1, characterized in that: The modifiers are Al-4.5P alloy and Al-10Sr alloy. The mass ratio of Al-4.5P alloy to Al-10Sr alloy is controlled to be (2-2.5):

1. When adding the modifier, Al-10Sr alloy is added first, and then Al-4.5P alloy is added. The total amount of modifier added is (0.9-1.0)% of the sum of the mass of ZL109 aluminum alloy and Al-30Si master alloy.

6. The method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration according to claim 1, characterized in that: The Al-30Si master alloy was polished and preheated at 200°C for 2 hours before being added to the ZL109 aluminum alloy melt; the probe of the ultrasonic vibration device was preheated in a heating furnace at 580-600°C for 25-35 minutes before ultrasonic vibration stirring; and the mold was preheated to 300°C before the melt was cast into the mold.

7. The method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration according to claim 1, characterized in that: The prepared hypereutectic aluminum-silicon alloy semi-solid slurry includes, by mass percentage, Si: 14.0-16.0%, Cu: 0.4-1.3%, Mg: 0.6-1.1%, Ni: 0.6-1.3%, P: 0.03-0.033%, Sr: 0.03-0.033%, and the balance Al, and the impurity content is less than 1%.

8. A hypereutectic aluminum-silicon alloy material, wherein the hypereutectic aluminum-silicon alloy material is prepared by the method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration according to any one of claims 1 to 6, wherein: The hypereutectic aluminum-silicon alloy material comprises, by mass percentage, Si: 14.0-16.0%, Cu: 0.4-1.3%, Mg: 0.6-1.1%, Ni: 0.6-1.3%, P: 0.03-0.033%, Sr: 0.03-0.033%, and the balance Al, and the impurity content is less than 1%.

9. Use of the hypereutectic aluminum-silicon alloy material according to claim 8 in automobile pistons.

10. A method for refining the size of primary silicon crystals and matrix grains in a hypereutectic aluminum-silicon alloy material, the method being achieved by implementing the method for preparing a hypereutectic aluminum-silicon alloy semi-solid slurry using ultrasonic vibration as claimed in any one of claims 1 to 6.

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