Method for preparing aluminum-based composite material based on melt overheating and rapid cooling molding
By superheating and rapid cooling of melt in aluminum-silicon alloy, Al2Y and TiB2 particles are generated, which solves the problem of reduced mechanical properties caused by the coarse primary silicon phase in aluminum-silicon alloy, and achieves the improvement of mechanical properties of aluminum-based composite materials and the expansion of industrial applications.
Patent Information
- Application Number
- CN202411669198.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-21
- Publication Date
- 2025-02-25
AI Technical Summary
Aluminum-silicon alloys contain a large number of crude primary silicon phases, resulting in a reduction in mechanical properties. The irregular shape of eutectic silicon also seriously reduces cutting performance, limiting its industrial applications.
Through melt overheating and rapid cooling treatment, Al2Y and TiB2 particles are generated, which improves the shape and grain refinement of eutectic silicon and improves the mechanical properties of aluminum-based composite materials.
It significantly improves the mechanical properties of aluminum alloy materials, improves grain structure, and enhances the tensile strength and fatigue strength of the materials, which are suitable for the production of automotive parts and mechanical parts.
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Figure CN119506642A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of aluminum-based composite material preparation, and in particular to a method for preparing aluminum-based composite material based on melt superheating and rapid cooling molding. Background Art
[0002] Aluminum-silicon alloys are considered as potential candidate materials for automotive, aerospace and electronic applications due to their high wear resistance, low density and low thermal expansion coefficient. In engineering applications, they are used to produce raw materials such as brake discs, engines, cylinder liners, pistons, etc., which can effectively reduce fuel consumption and improve automobile exhaust emissions. Conventional cast aluminum-silicon alloys have a widened crystallization temperature range due to the large addition of silicon. In addition, due to the low cooling rate during the solidification of aluminum-silicon alloys, this promotes the formation of primary silicon with coarse and complex morphological structures, such as five-petal stars, thick strips, octahedrons, and polygonal primary silicon. Under the action of external forces, the tips and corners of these complex and coarse primary silicon crystals distributed on the matrix will cause stress concentration. At the same time, the hard and brittle coarse silicon phase will also reduce its bonding strength with the matrix, significantly reducing the plasticity and wear resistance of the aluminum-silicon alloy, and will also seriously split the alloy matrix, significantly reducing other mechanical properties of the alloy. In addition, the segregation caused by the agglomeration of eutectic silicon phases during the solidification of aluminum-silicon alloys also affects the mechanical properties of the alloy.
[0003] There are currently multiple techniques to mitigate this heterogeneity in liquid alloys, including ultrasonic treatment, controlled solidification rate, addition of seeding phases and alloy additions, rapid cooling, and the application of melt superheating. Melt superheating provides a simple and effective way to improve solute homogeneity while minimizing casting defects. Melt superheating involves superheating the molten alloy to about 250-300°C above its liquidus temperature. This process significantly increases the thermal energy of the alloy, causing the ordered solute clusters to dissociate into single atoms. After superheating, the melt is maintained at an elevated temperature for a specified period of time and then rapidly cooled. Although the disruption of solute clusters reduces the number of effective nucleation sites, it ensures that solute homogeneity remains unchanged at the solidus temperature, thereby reducing nucleation events during solidification. Therefore, solidification under such conditions can produce a more uniform and fine structure, which exhibits enhanced age hardenability during subsequent artificial aging.
[0004] The improvement in mechanical properties observed in aluminum alloys subjected to melt overheating treatment is due to the increased dissolution of Si-Si clusters as the melt temperature increases. This phenomenon is particularly prominent when the melting temperature exceeds 800°C, causing the atomic density and coordination number of the aluminum-silicon alloy to drop rapidly. In order to improve the mechanical properties of aluminum-silicon alloys, the microstructure of the primary silicon distributed in the alloy must be refined and rounded, and small, spherical and evenly distributed primary silicon has always been the microstructure of primary silicon that researchers of high-silicon aluminum alloys want to obtain. Recent studies have shown that melt overheating causes the eutectic Si phase to transform from an irregular shape to an octahedral shape.
[0005] Rapid cooling is a method to improve the performance of aluminum alloys. It can significantly refine the size of the eutectic silicon phase of aluminum alloys. Currently, there are methods such as quenching, spray deposition, and melt spinning. Studies have shown that for aluminum-silicon alloys, intermetallic compounds will be formed or precipitated during the rapid solidification process or after rapid solidification and aging treatment. Their size is very small and evenly dispersed on the matrix, maintaining a good matching relationship with the matrix, significantly improving the performance of the alloy. Liquid nitrogen is widely used in industrial production as an efficient coolant with an extremely high cooling rate. During the solidification of molten alloys, at a very high cooling rate, metastable states are likely to appear. Therefore, rapid cooling technology has excellent prospects and application value. Summary of the invention
[0006] The present invention proposes a method for preparing aluminum-based composite materials based on melt superheating and rapid cooling molding, which mainly solves the problem that aluminum-silicon alloy contains a large amount of coarse primary silicon phase, which will significantly reduce the mechanical properties of the alloy, and the irregular shape of eutectic silicon will seriously reduce the cutting performance of the alloy, which will also lead to the problem that its industrial application is greatly limited. The present invention superheats the melt and rapidly cools it to generate Al2Y and TiB2 particle dispersed A356 alloy in situ, improves the shape of eutectic silicon in the alloy structure and refines the grains to obtain A356 aluminum-based composite materials with excellent mechanical properties, has great economic value, is easy to mass produce, and the produced aluminum-based composite materials can be used in the field of automotive parts, and are ideal materials for replacing steel to prepare automotive pistons and various mechanical parts.
[0007] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is:
[0008] A method for preparing aluminum-based composite materials based on melt superheating and rapid cooling molding, wherein aluminum-boron alloy and aluminum-titanium alloy are melted and stirred in a crucible, A356 alloy and yttrium powder are added to perform melt superheating treatment and keep the melt warm for a period of time, and the mold is placed in a liquid nitrogen environment for precooling, and then the casting liquid is poured into a cooling mold after degassing and slag removal to obtain an A356 aluminum-based composite material with TiB2 particles dispersed therein.
[0009] As a preferred technical solution of the present invention, the preparation method specifically comprises the following steps:
[0010] Step 1: Dry and crush the raw alloy ingot:
[0011] Drying aluminum-boron alloy and aluminum-titanium alloy, crushing and mixing them according to a certain weight ratio, crushing A356 aluminum alloy and mixing it with yttrium powder according to a certain weight ratio;
[0012] Step 2: Melting and stirring:
[0013] Preheat the crucible to a certain temperature, preheat for a period of time, then increase the temperature, put in the mixed aluminum-boron and aluminum-titanium alloy samples, make them molten and keep them warm;
[0014] Step 3: Melt overheating:
[0015] Add the crushed and mixed mixture of A356 aluminum alloy and yttrium powder in step 1 into the melting crucible, overheat to a certain temperature, and keep it warm for a period of time;
[0016] Step 4: Precooling the crucible:
[0017] The melt is slowly cooled to a certain temperature in the crucible argon atmosphere, and the mold is placed in a liquid nitrogen environment to cool for a period of time;
[0018] Step 5: Rapid cooling:
[0019] The stirred and mixed melt is poured into a mold and rapidly cooled to finally obtain a TiB2 particle dispersed A356 aluminum matrix composite material.
[0020] As a further preferred technical solution of the present invention, in the preparation method:
[0021] In the step 1, the weight ratio of the aluminum-boron alloy, the aluminum-titanium alloy, the A356 aluminum alloy and the yttrium powder is 1-2:1:6-10:1-4.
[0022] In step 2, the preheating temperature is 400-500° C., and the preheating time is 1-3 hours; the smelting temperature is 730-780° C., and the smelting time is 15-30 minutes.
[0023] In step 3, the melt superheating temperature is 950-1050° C., and the insulation time is 1-2 hours.
[0024] In step 4, the melt is cooled to 280-400° C. and then poured into the mold, and the mold is pre-cooled in liquid nitrogen for 20 minutes in advance.
[0025] The aluminum-based composite material prepared by the present invention, wherein the mass fraction of Al2Y and TiB2 particles in the aluminum-based composite material is 0.5-2.0%, can significantly improve the mechanical properties of the aluminum alloy material. Compared with the prior art, the beneficial effects of the present invention are as follows:
[0026] 1. The present invention adds highly active rare earth element Y to spontaneously react and provide energy for melt superheating treatment during the casting process. Different from the external heat supply in the traditional melt superheating operation, the spontaneously reacting melt can improve fluidity during superheating, significantly increasing the thermal energy of the TiB2 dispersed aluminum-silicon alloy, resulting in the dissociation of ordered eutectic silicon and TiB2 particle solute clusters into single atoms, ensuring the solute uniformity at the solidus temperature, and effectively alleviating the phenomenon that the eutectic silicon phase agglomerates during the solidification process of the aluminum-silicon alloy and causes segregation that affects the mechanical properties of the alloy. At the same time, the rare earth element Y easily forms compounds with hydrogen and oxygen, thereby achieving the purification effect of degassing and removing impurities during the melting process. The heat energy and fluidity generated by the yttrium reaction cause the eutectic silicon phase to transform from an irregular shape to an octahedral shape, making the eutectic silicon regular and round, effectively improving the mechanical properties of the TiB2 dispersed aluminum-silicon alloy.
[0027] 2. During the melt superheat treatment, the Al2Y intermetallic compound generated by adding the highly active rare earth element Y and the aluminum matrix refines the grains of the aluminum alloy. At the same time, the Al2Y intermetallic compound reduces the degree of nucleation supercooling during the solidification process of the composite material, and can become the nucleation site of the aluminum matrix to improve the solidification kinetics.
[0028] 3. Since the temperature of liquid nitrogen is about -196°C, it can provide a lower cooling rate than traditional water cooling, thus helping to achieve higher cooling efficiency and finer grain structure. Liquid nitrogen cooling can effectively maintain the solid solution state of elements such as magnesium and silicon in aluminum alloys, inhibit the formation of precipitation phases, and avoid the appearance of uneven precipitates in the subsequent aging process, thereby further improving the tensile strength and fatigue strength of the material;
[0029] 4. In the casting process of traditional TiB2 dispersed aluminum alloy, there is a phenomenon of TiB2 particles agglomerating and growing. Adding an appropriate amount of rare earth element Y with relative surface activity in the material preparation can effectively regulate the morphology, distribution and size of the enhanced particles. Liquid nitrogen cooling can prevent TiB2 from agglomerating and coarsening during the alloy cooling process and inhibit its excessive growth. At the same time, traditional water cooling may cause corrosion on the material surface, while liquid nitrogen is an inert gas, which avoids the potential impact of moisture on the material. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 It is a flow chart for preparing aluminum-based composite materials based on melt superheating and rapid cooling molding.
[0031] Figure 2 The fracture SEM and EDS images are of Example 1 of preparing the aluminum-based composite material by superheating the melt and rapidly cooling the melt.
[0032] Figure 3 The surface SEM and EDS images of Example 2 of the aluminum-based composite material prepared by superheating the melt and rapidly cooling the melt are shown.
[0033] Figure 4 It is a comparison chart of the tensile properties of Example 1 and Comparative Example 1 for preparing aluminum-based composite materials based on melt superheating and rapid cooling molding. DETAILED DESCRIPTION
[0034] See also Figure 1 As shown, the present invention proposes a method for preparing aluminum-based composite materials based on melt superheating and rapid cooling molding, wherein aluminum-boron alloy and aluminum-titanium alloy are melted and stirred in a crucible, A356 alloy and yttrium powder are added to perform melt superheating treatment and keep the melt warm for a period of time, and the mold is placed in a liquid nitrogen environment for precooling, and then the casting liquid is poured into a cooling mold after degassing and slag removal to obtain dispersed TiB2 particles to prepare A356 aluminum-based composite materials.
[0035] The present invention is further described in detail below in conjunction with embodiments and drawings.
[0036] Example 1
[0037] The TiB2 particle dispersed A356 aluminum-based composite material prepared in this embodiment uses 31.3g of aluminum-boron alloy (boron content is 3%), 18.54g of aluminum-titanium alloy (titanium content is 10%) and 148g of A356 aluminum alloy (wherein, Si 6.5-7.5%, Mg0.3%-0.4%, Ti 0.08%-0.2%, Sr 0-0.0015%, Al balance) and 19.1g of yttrium powder as raw materials. The aluminum-boron alloy and aluminum-titanium alloy are melted and stirred in a crucible, and the A356 alloy and yttrium powder are added to perform melt superheat treatment and keep the melt warm for a period of time. At the same time, the mold is placed in a liquid nitrogen environment for pre-cooling, and then the casting is poured into a cooling mold for degassing and slag removal to obtain dispersed TiB2 particles to prepare the A356 aluminum-based composite material.
[0038] The method for preparing the TiB2 particle dispersed A356 aluminum-based composite material in this embodiment is as follows:
[0039] Step 1: Dry and crush the raw alloy ingot:
[0040] The aluminum-boron alloy and the aluminum-titanium alloy are dried, crushed and mixed, and the A356 aluminum alloy is crushed and mixed with yttrium powder.
[0041] Step 2: Melting and stirring:
[0042] Preheat the crucible to 450°C for 1.5 hours, then raise the temperature to 750°C, put in the mixed aluminum-boron and aluminum-titanium alloy samples to make them molten, stir at 750°C for 15 minutes, and then let it stand and keep warm for 15 minutes.
[0043] Step 3: Melt overheating:
[0044] Add the crushed and mixed mixture of A356 aluminum alloy and yttrium powder in step 1 into the melting crucible, overheat the crucible to 1050° C., and keep it warm for 1 hour.
[0045] Step 4: Precooling the crucible:
[0046] The melt was slowly cooled to 400°C in an argon atmosphere in a crucible, and the mold was placed in a liquid nitrogen environment for precooling for 20 min.
[0047] Step 5: Rapid cooling:
[0048] The stirred and mixed melt is poured into a mold and rapidly cooled to obtain a TiB2 particle dispersed A356 aluminum matrix composite material.
[0049] Example 2
[0050] In this embodiment, TiB2 particle dispersed A356 aluminum-based composite material is prepared. 31.3g aluminum-boron alloy (boron content is 3%), 18.54g aluminum-titanium alloy (titanium content is 10%) and 148g A356 aluminum alloy (wherein, Si 6.5-7.5%, Mg0.3%-0.4%, Ti 0.08%-0.2%, Sr 0-0.0015%, Al balance) and 19.1g yttrium powder are used as raw materials. The aluminum-boron alloy and aluminum-titanium alloy are melted and stirred in a crucible, and the A356 alloy and yttrium powder are added to perform melt superheat treatment and keep the melt warm for a period of time. At the same time, the mold is placed in a liquid nitrogen environment for pre-cooling, and then the casting liquid is poured into a cooling mold for degassing and slag removal to obtain dispersed TiB2 particles to prepare the A356 aluminum-based composite material.
[0051] The method for preparing the TiB2 particle dispersed A356 aluminum-based composite material in this embodiment is as follows:
[0052] Step 1: Dry and crush the raw alloy ingot:
[0053] The aluminum-boron alloy and the aluminum-titanium alloy are dried, crushed and mixed, and the A356 aluminum alloy is crushed and mixed with yttrium powder.
[0054] Step 2: Melting and stirring:
[0055] Preheat the crucible to 450°C for 1.5 hours, then raise the temperature to 750°C, put in the mixed aluminum-boron and aluminum-titanium alloy samples to make them molten, stir at 750°C for 15 minutes, and then let it stand and keep warm for 15 minutes.
[0056] Step 3: Melt overheating:
[0057] Add the crushed and mixed mixture of A356 aluminum alloy and yttrium powder in step 1 into the melting crucible, overheat the crucible to 950° C., and keep it warm for 1 hour.
[0058] Step 4: Precooling the crucible:
[0059] The melt was slowly cooled to 400°C in an argon atmosphere in a crucible, and the mold was placed in a liquid nitrogen environment for precooling for 20 min.
[0060] Step 5: Rapid cooling:
[0061] The stirred and mixed melt is poured into a mold and rapidly cooled to obtain a TiB2 particle dispersed A356 aluminum matrix composite material.
[0062] Example 3
[0063] In this embodiment, TiB2 particle dispersed A356 aluminum-based composite material is prepared. 31.3g aluminum-boron alloy (boron content is 3%), 18.54g aluminum-titanium alloy (titanium content is 10%) and 148g A356 aluminum alloy (wherein, Si 6.5-7.5%, Mg0.3%-0.4%, Ti 0.08%-0.2%, Sr 0-0.0015%, Al balance) and 19.1g yttrium powder are used as raw materials. The aluminum-boron alloy and aluminum-titanium alloy are melted and stirred in a crucible, and the A356 alloy and yttrium powder are added to perform melt superheat treatment and keep the melt warm for a period of time. At the same time, the mold is placed in a liquid nitrogen environment for pre-cooling, and then the casting liquid is poured into a cooling mold for degassing and slag removal to obtain dispersed TiB2 particles to prepare the A356 aluminum-based composite material.
[0064] The method for preparing the TiB2 particle dispersed A356 aluminum-based composite material in this embodiment is as follows:
[0065] Step 1: Dry and crush the raw alloy ingot:
[0066] The aluminum-boron alloy and the aluminum-titanium alloy are dried, crushed and mixed, and the A356 aluminum alloy is crushed and mixed with yttrium powder.
[0067] Step 2: Melting and stirring:
[0068] Preheat the crucible to 450°C for 1.5 hours, then raise the temperature to 750°C, put in the mixed aluminum-boron and aluminum-titanium alloy samples to make them molten, stir at 750°C for 15 minutes, and then let it stand and keep warm for 15 minutes.
[0069] Step 3: Melt overheating:
[0070] Add the crushed and mixed mixture of A356 aluminum alloy and yttrium powder in step 1 into the melting crucible, overheat the crucible to 950° C., and keep it warm for 1 hour.
[0071] Step 4: Precooling the crucible:
[0072] The melt was slowly cooled to 280°C in an argon atmosphere in a crucible, and the mold was placed in a liquid nitrogen environment for precooling for 20 min.
[0073] Step 5: Rapid cooling:
[0074] The stirred and mixed melt is poured into a mold and rapidly cooled to obtain a TiB2 particle dispersed A356 aluminum matrix composite material.
[0075] Comparative Example 1
[0076] In this embodiment, TiB2 particle dispersed A356 aluminum-based composite material is prepared. 31.3g aluminum-boron alloy (boron content is 3%), 18.54g aluminum-titanium alloy (titanium content is 10%) and 148g A356 aluminum alloy (including Si 6.5-7.5%, Mg0.3%-0.4%, Ti 0.08%-0.2%, Sr 0-0.0015%, and Al balance) are used as raw materials. The aluminum-boron alloy, aluminum-titanium alloy and A356 alloy are melted and stirred in a crucible, and the mixture is kept warm for a period of time. Subsequently, the casting is degassed and poured into a mold, which is then put into water and rapidly cooled to obtain dispersed TiB2 particles to prepare the A356 aluminum-based composite material.
[0077] The method for preparing the TiB2 particle dispersed A356 aluminum-based composite material in this embodiment is as follows:
[0078] Step 1: Dry and crush the raw alloy ingot:
[0079] The aluminum-boron alloy and the aluminum-titanium alloy are dried, crushed and mixed, and the A356 aluminum alloy is crushed.
[0080] Step 2: Melting and stirring:
[0081] Preheat the crucible to 450°C for 1.5 hours, then raise the temperature to 750°C, put in the mixed aluminum-boron, aluminum-titanium alloy and A356 alloy samples to make them molten, stir at 750°C for 15 minutes, and then let it stand and keep warm for 15 minutes.
[0082] Step 3: Water-cooling quenching:
[0083] The stirred and mixed melt is poured into a mold, cooled to 400°C, and rapidly cooled in water to obtain dispersed TiB2 particles to prepare A356 aluminum-based composite materials.
[0084] Table 1. Relevant properties of A356 aluminum-based composite materials prepared in the embodiments of the present invention and the comparative examples
[0085]
[0086] It can be seen from the examples and comparative examples in Table 1 that melt overheating and liquid nitrogen rapid cooling can significantly improve hardness and tensile strength and reduce elongation. From the comparison between the examples, it can be seen that the tensile strength when the overheating temperature reaches 1050°C is better than the tensile strength when the overheating temperature is 950°C, and the hardness when the rapid cooling temperature is 400°C is better than the hardness when the cooling temperature is 280°C, indicating that the higher the overheating temperature, the higher the starting point of the rapid cooling temperature, and the better the mechanical properties.
[0087] Depend on Figure 2 It can be seen that the distribution of elements at the fracture is relatively diffuse, without obvious agglomeration, and has certain dimples, so the mechanical properties are good.
[0088] Depend on Figure 3 It can be seen that the Ti and B particles on the surface of the material are relatively dispersed and corresponding, indicating that the generated TiB2 is relatively small, and the Y element shows a certain agglomeration, indicating that the Al2Y particles have a larger particle size.
[0089] Depend on Figure 4 It can be seen that the tensile strength of Example 1 is significantly higher than that of Comparative Example 1, and the elongation decreases to a certain extent, indicating that the method of melt superheating and rapid cooling molding can improve the mechanical properties of the material.
[0090] The above contents are merely examples and explanations of the concept of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.
Claims
1. A method for preparing an aluminum-based composite material based on melt superheating and rapid cooling molding, characterized in that: Aluminum-boron alloy and aluminum-titanium alloy are melted and stirred in a crucible, and A356 alloy and yttrium powder are added to perform melt superheat treatment and keep the melt warm for a period of time. At the same time, the mold is placed in a liquid nitrogen environment for precooling, and then the casting liquid is poured into the cooling mold after degassing and slag removal to obtain TiB2 particle dispersed A356 aluminum-based composite material.
2. The method according to claim 1, characterized in that The preparation method specifically comprises the following steps: Step 1: Dry and crush the raw alloy ingots: Drying aluminum-boron alloy and aluminum-titanium alloy, crushing and mixing them according to a certain weight ratio, crushing A356 aluminum alloy and mixing it with yttrium powder according to a certain weight ratio; Step 2: Melting and stirring: Preheat the crucible to a certain temperature, preheat for a period of time, then increase the temperature, put in the mixed aluminum-boron and aluminum-titanium alloy samples, make them molten and keep them warm; Step 3: Melt overheating: Add the crushed and mixed mixture of A356 aluminum alloy and yttrium powder in step 1 into the melting crucible, overheat to a certain temperature, and keep it warm for a period of time; Step 4: Precooling the crucible: The melt is slowly cooled to a certain temperature in the crucible argon atmosphere, and the mold is placed in a liquid nitrogen environment to cool for a period of time; Step 5: Rapid cooling: The stirred and mixed melt is poured into a mold and rapidly cooled to finally obtain a TiB2 particle dispersed A356 aluminum matrix composite material.
3. The method according to claim 2, characterized in that In the step 1, the weight ratio of the aluminum-boron alloy, the aluminum-titanium alloy, the A356 aluminum alloy and the yttrium powder is 1-2:1:6-10:1-4.
4. The method according to claim 2, characterized in that In step 2, the preheating temperature is 400-500° C., and the preheating time is 1-3 hours; the smelting temperature is 730-780° C., and the smelting time is 15-30 minutes.
5. The method according to claim 2, characterized in that In step 3, the melt superheating temperature is 950-1050° C., and the insulation time is 1-2 hours.
6. The method according to claim 2, characterized in that In step 4, the melt is cooled to 280-400° C. and then poured into the mold, and the mold is pre-cooled in liquid nitrogen for 20 minutes in advance.
7. The aluminum-based composite material prepared by the method according to any one of claims 1 to 6, wherein the mass fraction of Al2Y and TiB2 particles in the aluminum-based composite material is 0.5-2.0%, which can significantly improve the mechanical properties of the aluminum alloy material.