Aluminum-titanium-boron-carbon-niobium rare earth master alloy refiner and its preparation method and application

Abstract

The present invention discloses an aluminum-titanium-boron-carbon-niobium-rare earth master alloy refiner and its preparation method and application, relating to the technical field of refiners. The refiner comprises the following components by mass percentage: 4.5-5.5% titanium, 0.8-1.2% boron, 0.1-0.3% carbon, 0.1-1.5% niobium, and 0.2-0.5% rare earth, with the balance being aluminum. The preparation method comprises the following steps: ball-milling a titanium source, a carbon source, and aluminum powder to mix the powders, and hydraulically forming a prefabricated block; heating an aluminum ingot until completely melted, and then pressing the mixed powder prefabricated blocks into an aluminum melt in batches to obtain a mixed melt; sequentially adding an aluminum-boron alloy, an aluminum-niobium alloy, and a rare earth alloy to the melt to melt, then adding carbon hexachloride for slag removal and refining, and then pouring the mixture into a mold for cooling. The refiner can significantly improve the grain structure of aluminum-silicon alloys. The introduction of niobium and rare earth effectively improves the anti-fading and anti-poisoning properties of high-silicon-content aluminum-silicon alloys, and can effectively refine the aluminum-silicon alloys.

Description

Technical Field

[0001] The present invention relates to the technical field of refiners, and in particular to an aluminum-titanium-boron-carbon-niobium rare earth master alloy refiner, a preparation method thereof, and an application thereof. Background Art

[0002] To combat global warming caused by industrial fuels, new energy vehicles have emerged. First and foremost, lightweight design is key. Data shows that for every 10% weight reduction in new energy vehicles, the driving range can increase by 5%-6%. Among the many automotive alloys, aluminum-silicon cast aluminum alloys offer excellent casting fluidity, high strength, excellent machinability, low shrinkage, and minimal thermal cracking tendency. They are currently the most widely used hypoeutectic Al-Si material for automotive and motorcycle wheels, and are also widely used in the aerospace industry. As automotive design evolves towards lighter weight, energy efficiency, and a wider variety of options, the use of cast aluminum alloys in the automotive industry is increasing, and their scope of application continues to expand.

[0003] However, during the casting process, due to the slow cooling rate, coarse α-Al phases, needle-shaped eutectic Si phases of varying lengths and thicknesses, and pores are formed. These coarse α-Al phases, needle-shaped eutectic Si phases, and pores are similar to non-metallic inclusions in steel, which can significantly reduce the performance of A356 aluminum alloy, resulting in reduced strength and increased brittleness of the castings. In actual production, the use of refinement and modification treatment can not only reduce the grain size of the alloy and obtain finer grains, but also reduce defects such as pores in the castings. In addition, the refinement and modification treatment can also transform the needle-shaped eutectic Si phase into short rods or granules, changing its morphology, thereby fundamentally improving the performance of high-silicon aluminum-silicon alloys.

[0004] Currently, the widely used Al-Ti-B and Al-Ti-C refiners in industry, while offering significant grain-refining benefits, also have drawbacks. Their grain-refining performance is limited by the presence of high Si content in the Al alloy (especially exceeding 6.5wt% in Al-Si casting alloys) or a certain amount of Zr in the Al alloy, a phenomenon known as Si / Zr poisoning. The grain-refining phases TiB2 and TiC within these refiners tend to aggregate and precipitate in the aluminum melt, resulting in locally coarse microstructures after solidification and, in other words, poor recession resistance. Furthermore, the presence of elements such as Cr, Zr, and Si in the alloy can further lead to "poisoning." Summary of the Invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide an aluminum-titanium-boron-carbon-niobium-rare earth master alloy refiner and its preparation method and application, which can significantly improve the grain structure of aluminum-silicon alloy, and has excellent anti-poisoning and anti-fading properties, and can effectively refine aluminum-silicon alloy.

[0006] The technical solution of the present invention to solve the above technical problems is as follows: an aluminum-titanium-boron-carbon-niobium-rare earth master alloy refiner is provided, which includes the following components, in mass percentage: titanium (Ti) 4.5-5.5%, boron (B) 0.8-1.2%, carbon (C) 0.1-0.3%, niobium (Nb) 0.1-1.5% and rare earth (Re) 0.2-0.5%, and the balance is aluminum (Al).

[0007] Furthermore, the following components are included in percentage by mass: 5% titanium, 1% boron, 0.2% carbon, 1% niobium, 0.3% rare earth, and the balance being aluminum.

[0008] Furthermore, the rare earth is lanthanum (La).

[0009] Furthermore, the mass percentage of rare earth is one of 0.2%, 0.3%, 0.4% and 0.5%.

[0010] Furthermore, the inevitable impurity content in the aluminum-titanium-boron-carbon-niobium rare earth master alloy refiner is ≤0.15%.

[0011] The present invention also provides a method for preparing the above-mentioned aluminum-titanium-boron-carbon-niobium rare earth master alloy refiner, comprising the following steps:

[0012] Step 1: ball-milling the titanium source, carbon source and aluminum powder, and then hydroforming them to obtain a prefabricated block;

[0013] Step 2: Melt pure aluminum at 750-800°C, then add the prefabricated block obtained in step 1, melt, and heat-insulate and stir to obtain a mixed melt;

[0014] Step 3: heating the mixed melt obtained in step 2 to 800-1000° C., adding aluminum-boron alloy to melt, cooling to 750-850° C., adding aluminum-niobium alloy to melt, then adding rare earth to melt and performing heat preservation and stirring treatment, then adding carbon hexachloride to remove slag and refine, and finally pouring into a mold to cool, thereby obtaining an aluminum-titanium-boron-carbon-niobium rare earth master alloy refiner.

[0015] This solution involves first ball-milling the Ti and C sources with aluminum powder to create a mixed powder, which is then added to the molten aluminum before other elements, ensuring complete dissolution of the Ti and C elements. After the reaction is complete, C₂Cl₆ is added to the aluminum melt for degassing and refining. C₂Cl₆ decomposes to produce gas, but the resulting Cl₂ and C₂Cl₆ gases are incompatible with the aluminum melt.

[0016] Furthermore, in step 1, the titanium source is titanium powder; and the carbon source is graphite.

[0017] Furthermore, in step 1, the ball milling speed is 150-250 r / min, the ball-to-material ratio is 3:1, and the ball milling time is 1-2 h.

[0018] The ball milling process can increase the reactivity of the raw material powder, making it easier to react in the melt; at the same time, high-energy ball milling can also improve the dispersibility of the powder, ensuring that the reaction is evenly distributed throughout the melt.

[0019] Furthermore, in step 1, the hydraulic pressure is 15-20 kN and the holding time is 10-20 s.

[0020] Furthermore, in step 1, hydraulic pressure is performed using a TYA-600 hydraulic testing machine.

[0021] Furthermore, in step 1, the preform is cylindrical and has a size of Φ40 mm×15 mm.

[0022] Furthermore, in step 2, the preform is added to the melt in two steps.

[0023] The beneficial effect of adopting a further technical solution is that, due to the poor wettability of C with aluminum alloy, adding C in batches can allow the reaction to proceed fully.

[0024] Furthermore, in step 2, the preform is added to the melt using a graphite bell jar.

[0025] Furthermore, in steps 2 and 3, the mixture is first kept warm for 20-30 minutes and then stirred at a rate of 2000-3000 r / min for 2-5 minutes. The mixture is kept warm and stirred each time the alloy is added to the melt.

[0026] The beneficial effects of adopting the further technical solution are: eliminating the second phase segregation phenomenon that may exist in the refiner and promoting the uniform distribution of chemical components in the melt.

[0027] Furthermore, in step 3, after stirring, the heat source is removed and 20 kHz ultrasonic vibration is applied for 1-2 minutes.

[0028] Furthermore, in step three, the mold is a graphite mold; the mold is preheated to 100-200°C before pouring.

[0029] Furthermore, in step three, the aluminum-boron alloy is Al-3B alloy; and the aluminum-niobium alloy is Al-4Nb alloy.

[0030] The beneficial effects of adopting further technical solutions are: the use of aluminum-boron alloy has higher boron utilization, better dispersion (the aluminum matrix in Al-3B is compatible with the Al-Ti-C system, avoiding competitive reactions between carbon sources and boron sources, and ensuring the simultaneous generation of TiC and TiB2), less pollution, more stable process control, environmental protection and better refinement effect; dense Al2O3 is generated on the surface of the Al-Nb alloy, blocking oxygen from contacting the Nb inside, and the Al-Nb carrier promotes the epitaxial growth of REB6 on the NbC surface.

[0031] Furthermore, in step 3, rare earth can also be added in the form of aluminum alloy, for example, rare earth lanthanum can be added in the form of aluminum-lanthanum alloy Al-10La.

[0032] The beneficial effect of adopting a further technical solution is that the introduction of La in the form of Al-10La pre-alloy can reduce the oxidation tendency of La, while utilizing the coating effect of Al to reduce burning loss.

[0033] Furthermore, the alloy is rapidly cooled after being poured into the mold in order to suppress the segregation of La and avoid the growth of Al-La phase and Al3Ti phase.

[0034] The present invention also provides the use of the above-mentioned aluminum-titanium-boron-carbon-niobium-rare earth master alloy refiner in refining aluminum-silicon alloys with a silicon content exceeding 6.5 wt%.

[0035] Furthermore, the amount of the aluminum-titanium-boron-carbon-niobium rare earth master alloy refiner is 0.2-1 wt% of the aluminum-silicon alloy.

[0036] Furthermore, the aluminum silicon alloy is A356 alloy.

[0037] The present invention has the following beneficial effects:

[0038] 1. The preparation method of the present invention not only provides new heterogeneous nucleation sites by rationally controlling the addition amount of niobium and lanthanum elements and the preparation conditions, but also solves the problems of poor wettability of Al and C and TiC aggregation. In addition, this method effectively reduces the aggregation of TiB2 phase particles, inhibits the generation of harmful Al4C3 phase, makes the size and distribution of Al3Ti phase particles more reasonable, and produces a new effective refined phase Al 20 Ti2La, (Ti / Nb)C and (Nb / Ti)Al3, while reducing the gas content inside the alloy.

[0039] 2. This method does not require complex equipment or high temperature and high pressure conditions, nor does it require the use of inert gas, thereby greatly simplifying the preparation process. The refiner prepared by this method has the characteristics of simple process, low cost, significant refinement effect, and environmental friendliness.

[0040] 3. Compared with the traditional fluoride salt reaction, the preparation method of the present invention reduces the emission of harmful gases and uses aluminum boron, aluminum niobium and aluminum lanthanum master alloys to avoid the introduction of other impurities.

[0041] 4. The refiner of the present invention can significantly improve the grain structure of aluminum-silicon alloy, and has excellent anti-poisoning and anti-fading properties, and plays an effective refining role in the refinement of aluminum-silicon alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 The XRD patterns of the refiners of Example 1 and Comparative Example 1 are shown;

[0043] Figure 2 The microstructure diagrams of the refiners of Example 1 and Comparative Example 1 are shown;

[0044] Figure 3 The macroscopic images of grains of A356 alloy before and after refinement;

[0045] Figure 4 This is a macroscopic image of the grains of A356 alloy after being refined by the refiner in Example 1;

[0046] Figure 5 This is a macroscopic image of the grains of A356 alloy after refinement by the refiner in comparative example 1;

[0047] Figure 6 This is the macroscopic image of the grains of A356 alloy after being refined by the refiner in comparative example 2. DETAILED DESCRIPTION

[0048] The principles and features of the present invention are described below. The examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. In the examples, where specific conditions are not specified, conventional conditions or manufacturer-recommended conditions were used. Reagents or instruments used where the manufacturer is not specified are conventional products that can be purchased commercially.

[0049] Example 1

[0050] An aluminum-titanium-boron-carbon-niobium-rare earth master alloy refiner (Al-5Ti-1B-0.2C-0.5Nb-0.2La), comprising the following components by mass percentage: 5% titanium, 1% boron, 0.2% carbon, 0.5% niobium, and 0.2% rare earth (lanthanum), with an impurity content of ≤0.1% and the balance being aluminum;

[0051] The preparation method thereof comprises the following steps:

[0052] Step 1: Titanium powder, graphite powder, and aluminum powder were ball-milled for 1.5 h at a speed of 200 r / min, with a ball-to-material ratio of 3:1. The mixture was then hydroformed at a pressure of 18 kN and a holding time of 15 s to obtain a prefabricated block. The prefabricated block was cylindrical and had dimensions of Φ40 mm × 15 mm.

[0053] Step 2: Melt pure aluminum at 760°C, then add the prefabricated block obtained in step 1 into a graphite bell jar and melt it twice, keeping the mixture at this temperature for 25 minutes each time and stirring at 2500 rpm for 3 minutes to obtain a mixed melt;

[0054] Step 3: The mixed melt obtained in step 2 is heated to 900°C, aluminum-boron alloy Al-3B is added and melted, the temperature is lowered to 800°C, aluminum-niobium alloy is added and melted, and then aluminum-lanthanum alloy Al-10La is added and melted, the mixture is kept warm for 25 minutes, stirred at a rate of 2500 r / min for 3 minutes, the heat source is removed and 20 kHz ultrasonic vibration is applied for 2 minutes, and then carbon hexachloride is added for deslagging and refining, and finally poured into a graphite mold preheated to 150°C and rapidly cooled to obtain an aluminum-titanium-boron-carbon-niobium rare earth master alloy refiner.

[0055] Example 2

[0056] An aluminum-titanium-boron-carbon-niobium rare earth master alloy refiner (Al-5Ti-1B-0.2C-1Nb-0.2La) is different from Example 1 in that the mass percentage of niobium is 1%.

[0057] Example 3

[0058] An aluminum-titanium-boron-carbon-niobium rare earth master alloy refiner (Al-5Ti-1B-0.2C-1.5Nb-0.2La) is different from Example 1 in that the mass percentage of niobium is 1.5%.

[0059] Example 4

[0060] An aluminum-titanium-boron-carbon-niobium rare earth master alloy refiner (Al-5Ti-1B-0.2C-0.5Nb-0.3La) is different from Example 1 in that the mass percentage of lanthanum is 0.3%.

[0061] Example 5

[0062] An aluminum-titanium-boron-carbon-niobium rare earth master alloy refiner (Al-5Ti-1B-0.2C-0.5Nb-0.5La) is different from Example 1 in that the mass percentage of lanthanum is 0.5%.

[0063] Example 6

[0064] An aluminum-titanium-boron-carbon-niobium-rare earth master alloy refiner comprising the following components by mass percentage: 4.5% titanium, 0.1% carbon, 0.5% niobium, and 0.2% rare earth, with an impurity content of ≤0.15% and the balance being aluminum;

[0065] The preparation method thereof comprises the following steps:

[0066] (1) Titanium powder, graphite powder and aluminum powder were ball-milled at 250 r / min for 1 h with a ball-to-material ratio of 3:1. The mixture was then hydroformed at a pressure of 15 kN and a holding time of 20 s to obtain a prefabricated block.

[0067] (2) Melt pure aluminum at 750°C, then add the prefabricated block obtained in step 1 into a graphite bell jar and melt it twice, keeping the temperature for 20 minutes each time and stirring at 2000 r / min for 2 minutes to obtain a mixed melt;

[0068] (3) The mixed melt obtained in step 2 is heated to 800°C, and aluminum-boron alloy Al-3B is added to melt. After cooling to 750°C, aluminum-niobium alloy is added to melt, and then aluminum-lanthanum alloy Al-10La is added to melt. The mixture is kept warm for 20 minutes, stirred at a rate of 2000 r / min for 2 minutes, and then carbon hexachloride is added for deslagging and refining. Finally, the mixture is poured into a graphite mold preheated to 100°C and rapidly cooled to obtain an aluminum-titanium-boron-carbon-niobium rare earth intermediate alloy refiner.

[0069] Example 7

[0070] An aluminum-titanium-boron-carbon-niobium-rare earth master alloy refiner, comprising the following components by mass percentage: 5.5% titanium, 1.2% boron, 0.3% carbon, 1.5% niobium, and 0.5% rare earth, with an impurity content of ≤0.15% and the balance being aluminum;

[0071] The preparation method thereof comprises the following steps:

[0072] (1) Titanium powder, graphite powder and aluminum powder were ball-milled at 150 r / min for 2 h with a ball-to-material ratio of 3:1. The preformed blocks were then hydraulically formed at a pressure of 20 kN and a holding time of 10 s.

[0073] (2) pure aluminum was melted at 800°C, and then the prefabricated block obtained in step 1 was added to the graphite bell jar and melted twice, each time keeping the temperature for 30 minutes and stirring at 3000 r / min for 5 minutes to obtain a mixed melt;

[0074] (3) The mixed melt obtained in step 2 is heated to 1000°C, and aluminum-boron alloy Al-3B is added to melt. After cooling to 850°C, aluminum-niobium alloy is added to melt, and then aluminum-lanthanum alloy Al-10La is added to melt. The mixture is kept warm for 20 minutes and stirred at a rate of 3000 r / min for 5 minutes. Then, carbon hexachloride is added for deslagging and refining. Finally, the mixture is poured into a graphite mold preheated to 200°C and rapidly cooled to obtain an aluminum-titanium-boron-carbon-niobium rare earth intermediate alloy refiner.

[0075] Comparative Example 1

[0076] An Al-Ti-BC master alloy refiner comprises the following components by mass percentage: 5% titanium, 1% boron and 0.2% carbon, with an impurity content of ≤0.15% and the balance being aluminum.

[0077] Comparative Example 2

[0078] An aluminum-titanium-boron-carbon-rare-earth master alloy refiner (Al-5Ti-1B-0.2C-0.2La) is different from Example 1 in that niobium is not added in step three.

[0079] Test Example 1

[0080] (1) In order to characterize the composition of the refiner, X-ray diffraction analysis was performed on the refiners of Example 1 and Comparative Example 1, and the results are as follows: Figure 1 As shown, the phase composition of the refiner in Example 1 is α-Al, TiB2, TiC, Al3Ti, Al 20 Ti2La, (Ti,Nb)C and (Ti,Nb)Al3 phases.

[0081] (2) In order to observe the microstructure of the refiner, the refiners of Example 1 and Comparative Example 1 were characterized by scanning electron microscopy. The results are as follows: Figure 2 shown.

[0082] Depend on Figure 2 It can be seen that the refiners of Example 1 and Comparative Example 1 have uniform structures, the particle sizes of refined nucleation points Al3Ti are 10 μm and 20 μm respectively, and the particle sizes of TiC and TiB2 are less than 1 μm.

[0083] Test Example 2

[0084] The prepared refiner master alloy ingots of Example 1, Comparative Example 1 and Comparative Example 2 were crushed and then ball milled using a planetary ball mill with a ball-to-material ratio of 10:1 and a rotation speed of 300-400 rpm for 30 hours, while adding 0.5% ethanol to prevent cold welding.

[0085] Weigh the aluminum-silicon A356 alloy into a clay crucible and place it in a crucible resistance furnace at a temperature of 770°C to make it into a molten state; then weigh the ball-milled refiner according to 0.5% of the mass of the molten aluminum-silicon alloy, add the refiner to the molten aluminum-silicon alloy and keep it warm for a certain period of time. Then take the crucible out of the furnace, stir the melt thoroughly, and pour it into a cast iron mold. Cool and demold to obtain the refined A356 alloy ingot. The grain macrographs of the original A356 alloy ingot, the A356 alloy refined by the refiner in Example 1, the A356 alloy refined by the refiner in Comparative Example 1, and the A356 alloy refined by the refiner in Comparative Example 2 are shown respectively. Figure 3 、 Figure 4 、 Figure 5 and Figure 6 shown.

[0086] Depend on Figure 3 、 Figure 4 、 Figure 5 and Figure 6As can be seen, the average grain size of the original A356 alloy exceeded 1500 μm. After refinement with the refiners of Example 1, Comparative Example 1, and Comparative Example 2, the average grain size of the A356 alloy ingots was reduced to below 90 μm, 150 μm, and 112 μm, respectively, representing 6%, 10%, and 7.5% of the original A356 alloy. Comparative Example 2 shows that niobium significantly enhances the recession resistance of the refiner. Grains begin to coarsen significantly after only 60 minutes of rare earth element addition, demonstrating that the refiner of Example 1 can effectively improve the grain structure of the aluminum-silicon alloy.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements or improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A refiner for aluminum-titanium-boron-carbon-niobium rare earth master alloy, characterized in that: The composition is composed of the following components by mass percentage: 4.5-5.5% titanium, 0.8-1.2% boron, 0.1-0.3% carbon, 0.1-1.5% niobium and 0.2-0.5% rare earth, with the balance being aluminum; the rare earth is lanthanum; The preparation method of the aluminum-titanium-boron-carbon-niobium rare earth master alloy refiner comprises the following steps: Step 1: ball-milling the titanium source, carbon source and aluminum powder, and then hydraulically forming them to obtain a prefabricated block; Step 2: Melt pure aluminum at 750-800°C, then add the prefabricated block obtained in step 1, melt, and heat-insulate and stir to obtain a mixed melt; Step 3: heating the mixed melt obtained in step 2 to 800-1000° C., adding aluminum-boron alloy to melt, cooling to 750-850° C., adding aluminum-niobium alloy to melt, then adding rare earth to melt and performing heat preservation and stirring treatment, then adding carbon hexachloride to remove slag and refine, and finally pouring into a mold to cool, thereby obtaining an aluminum-titanium-boron-carbon-niobium rare earth master alloy refiner.

2. The aluminum-titanium-boron-carbon-niobium rare earth master alloy refiner according to claim 1, characterized in that: It is composed of the following components by mass percentage: 5% titanium, 1% boron, 0.2% carbon, 1% niobium and 0.3% rare earth, with the balance being aluminum.

3. The aluminum-titanium-boron-carbon-niobium rare earth master alloy refiner according to claim 1, characterized in that: In step 1 of the preparation method, the titanium source is titanium powder; and the carbon source is graphite.

4. The aluminum-titanium-boron-carbon-niobium rare earth master alloy refiner according to claim 1, characterized in that: In step 1 of the preparation method, the hydraulic pressure is 15-20 kN and the holding time is 10-20 s.

5. The aluminum-titanium-boron-carbon-niobium rare earth master alloy refiner according to claim 1, characterized in that: In step 2 and step 3 of the preparation method, the mixture is first kept warm for 20-30 minutes and then stirred at a rate of 2000-3000 r / min for 2-5 minutes.

6. The aluminum-titanium-boron-carbon-niobium rare earth master alloy refiner according to claim 1, characterized in that: In step three of the preparation method, the aluminum-boron alloy is an Al-3B alloy; and the aluminum-niobium alloy is an Al-4Nb alloy.

7. Use of the aluminum-titanium-boron-carbon-niobium-rare earth master alloy refiner according to any one of claims 1 to 6 in refining an aluminum-silicon alloy having a silicon content exceeding 6.5 wt%.

8. The use according to claim 7, characterized in that The amount of the aluminum-titanium-boron-carbon-niobium-rare-earth master alloy refiner is 0.2-1 wt% of the aluminum-silicon alloy.

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