Al-Ti-C-Ce intermediate alloy with titanium carbide as Ti source and C source as well as preparation method and application of Al-Ti-C-Ce intermediate alloy

Abstract

The invention discloses an Al-Ti-C-Ce intermediate alloy with titanium carbide as a Ti source and a C source and a preparation method and application thereof.The preparation method comprises the steps that titanium carbide powder and aluminum powder are mixed and subjected to ball milling to obtain core-shell structure composite powder with TiC coated with Al, the core-shell structure composite powder is subjected to compression molding to obtain prefabricated blocks, the prefabricated blocks are pressed into the bottom of an aluminum melt in batches through a graphite bell jar, and the aluminum melt is subjected to heat treatment to obtain the Al-Ti-C-Ce intermediate alloy with the Ti source and the C source. The preparation method comprises the following steps: adding an Al-30Ce intermediate alloy, carrying out first heat preservation at 760-850 DEG C, cooling to 700-750 DEG C, adding the Al-30Ce intermediate alloy, carrying out second heat preservation, deslagging and refining, and pouring into a mold to obtain the Al-Ti-C-Ce intermediate alloy; according to the Al-Ti-C-Ce intermediate alloy provided by the invention, A356 alloy grains are refined to 106 microns (ASTM 5 level), and a low-content system can still maintain the refining level that the grain size is smaller than 120 microns.

Description

Technical Field

[0001] The present invention relates to the technical field of refiners, and in particular to an Al-Ti-C-Ce master alloy using titanium carbide as a Ti source and a C source, and a preparation method and application thereof. Background Art

[0002] Aluminum alloys are increasingly used in various fields of society today, and performance requirements are becoming increasingly important. Producing high-quality as-cast structures is crucial. Research has shown that when aluminum-based alloys achieve a uniformly refined equiaxed grain structure, their mechanical strength, plastic deformation capacity, and formability all reach optimal levels. Currently, the most widely used method for material refinement is the addition of grain refiners.

[0003] Al-Ti-C master alloys, a key component of aluminum alloy grain refiners, have seen significant progress in their preparation processes, refinement mechanisms, and applications since their initial introduction in the 1970s. The development of Al-Ti-C master alloys stemmed from a need to improve upon traditional Al-Ti-B refiners. In 1983, Banerji et al. first proposed the use of TiC particles as heterogeneous nucleation sites for α-Al. Studies have shown that the lattice constant mismatch between TiC (a=0.432 nm) and α-Al (a=0.404 nm) is only 6.9%, significantly superior to the 8.6% mismatch between TiB and TiC, resulting in higher nucleation efficiency. However, current Al-Ti-C refiners still face challenges during their preparation, including poor wettability of the carbon source with the molten aluminum, difficulty in combining the carbon source with Ti atoms in the molten aluminum to produce a sufficient number of TiC particles, uneven TiC particle distribution, and severe agglomeration, limiting their industrial application. Summary of the Invention

[0004] In order to solve the above technical problems, the first object of the present invention is to provide a method for preparing an Al-Ti-C-Ce master alloy using titanium carbide as a Ti source and a C source.

[0005] The second object of the present invention is to provide an Al-Ti-C-Ce master alloy prepared by the above preparation method.

[0006] The third object of the present invention is to provide an application of the Al-Ti-C-Ce master alloy prepared by the above-mentioned preparation method. Using the Al-Ti-C-Ce master alloy as a refiner can significantly improve the grain structure of the aluminum-silicon alloy, and has excellent anti-poisoning and anti-fading properties, which can effectively refine the aluminum-silicon alloy.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] The present invention discloses a method for preparing an Al-Ti-C-Ce master alloy using titanium carbide as a Ti source and a C source. The method comprises the following steps: mixing titanium carbide powder with aluminum powder and ball milling to obtain a composite powder having a core-shell structure of Al-coated TiC; pressing the composite powder having a core-shell structure of Al-coated TiC to obtain prefabricated blocks; pressing the prefabricated blocks into the bottom of an aluminum melt in batches through a graphite bell jar; performing a first heat preservation at 760-850°C; then cooling the prefabricated blocks to 700-750°C; adding an Al-30Ce master alloy; performing a second heat preservation; then performing slag removal and refining; and finally pouring the prefabricated blocks into a mold to obtain the Al-Ti-C-Ce master alloy.

[0009] The Al-Ti-C-Ce master alloy has the following composition by mass percentage: Ti: 0.5-7%, C: 0.5-2%, Ce: 0.05-1%, and the balance is Al.

[0010] The preparation method of the present invention comprises the following steps: firstly, titanium carbide powder and aluminum powder are mixed and ball-milled to obtain a composite powder of a core-shell structure of Al-coated TiC, and then the composite powder is pressed into a prefabricated block. The prefabricated block is first added into aluminum melt, and an interface reaction TiC+3Al→TlAl3+C occurs on the surface of the prefabricated block and the aluminum liquid. Then, an Al-30Ce master alloy is added to react 2Al3Ti+Ce+14Al→Al 20 The freed Ti can further react with Al to form Al3Ti, and finally the Al-Ti-C-C master alloy prepared in the present invention has the phases of TiC, Al3Ti, Al 20 Ti2Ce is mainly used as a new heterogeneous nucleation site, which refines the grains and Al 20 The grain boundary pinning effect of Ti2Ce inhibits the slip of grain boundaries and improves the high-temperature elongation of the material.

[0011] In the present invention, TiC is used to replace the Ti source and the C source, and there is no need for a strong exothermic reaction to synthesize TiC on site, and the growth of harmful phases of Al4C3 and Ce2C is avoided. However, TiC powder is used directly as a raw material. First, titanium carbide powder and aluminum powder need to be mixed and ball-milled to obtain a core-shell structure composite powder of Al-coated TiC. If the coating structure is not formed, gravity segregation occurs and TiC sinks to form a local high hardness. The contact angle between TiC and aluminum is greater than 120°, and the powder is exposed to the surface of the melt, resulting in floating loss and oxidation to generate TiO2 / Al2O3. In addition, the prefabricated block needs to be added to the aluminum melt first, and after keeping it warm for a period of time, the Al-30Ce intermediate alloy is added. If the prefabricated block and the Al-30Ce intermediate alloy are added to the aluminum melt simultaneously, Ce will react with TiC to generate a hard and brittle Ce2C hard and brittle phase, and cause serious Ce burning.

[0012] The present invention adopts a slightly higher holding temperature in the first holding stage to make TiC and aluminum fully react to form Al3Ti. Then, the temperature is slightly lowered and Al-30Ce master alloy is added to make Ce react with Al3Ti to form Al3Ti. 20 Ti2Ce.

[0013] In a preferred embodiment, the particle size of the titanium carbide powder is 1.0-2.0 μm, and the particle size of the aluminum powder is 45-75 μm.

[0014] Experiments have found that the performance is best when the particle size of titanium carbide powder and aluminum powder is controlled within the above range. If the particle size of titanium carbide powder is too large, uneven coating will occur, resulting in exposed TiC. If the particle size is too small, it is easy to agglomerate. If the particle size of aluminum powder is too large, the aluminum powder will not be ductile enough and cannot be completely coated. If the particle size is too small, it is also easy to agglomerate.

[0015] In a preferred embodiment, the titanium carbide powder is first dried in a vacuum environment at 100-200°C for 2-4 hours with a vacuum degree of ≤10 -2 Vacuum drying the titanium carbide powder is not only a physical dehydration process, but also a core pretreatment to block surface chemical corrosion and ensure nano-dispersion and interfacial reaction. If the TiC is not dried, it will absorb water molecules to form TiO2-OH, which has a large contact angle and will cause agglomeration during ball milling due to water absorption.

[0016] In a preferred embodiment, the Al-coated TiC core-shell composite powder has a mass ratio of TiC:Al of 1:2-4. In the present invention, the mass ratio of TiC to Al in the core-shell composite powder must be effectively controlled. Excessive TiC (>1:2) causes free TiC to react with Ce to form Ce2C3, increasing the aluminum burnout rate. Furthermore, the aluminum coating becomes thinner, preventing the melt from fully infiltrating the aluminum. Excessive Al (<1:4) causes excess aluminum to consume cerium to form CeAl4, reducing the effective Ce content and degrading the refinement effect.

[0017] In a preferred embodiment, the ball mill has a rotation speed of 150-250 r / min, preferably 150-220 r / min, a ball milling time of 30-60 min, a ball-to-material ratio of 10-15:1, preferably 10-12:1, and the grinding balls are made of WC-Co.

[0018] Because Al is a soft metal, it easily undergoes plastic deformation under the high-energy collisions of ball milling, forming flakes or flat particles. TiC, a hard ceramic, primarily serves as a core to maintain its shape during ball milling. Therefore, ball milling allows Al to undergo repeated collisions, allowing the deformed Al to adhere tightly to the TiC surface under mechanical force. The milling process also promotes physical and chemical bonding at the interface between the Al and TiC, ultimately forming a coating on the TiC surface. The ball milling process reduces the contact angle of the pre-coated TiC in the molten aluminum. In conventional processes, the contact angle of free graphite is higher, leading to cerium accumulation at the interface, forming CeC2 inclusions. Ball milling also enhances the reactivity of the raw powder, making it more reactive in the melt. This results in a core-shell composite powder with Al-coated TiC, preferentially forming AlTi3 and suppressing the formation of the detrimental Al4C3 phase. Furthermore, the direct addition of TiC significantly increases Ce utilization. High-energy ball milling also improves powder dispersibility, ensuring uniform distribution of the reaction throughout the melt.

[0019] However, to obtain Al-coated TiC core-shell structure composite powder, it is necessary to control the rotation speed, time, and ball-to-material ratio so that the energy is sufficient to drive Al deformation but not excessively destroy the TiC structure, so that it preferentially deforms and wraps the hard TiC. If the ball milling time is too short, the coating is incomplete, and the TiC particles are not fully wrapped by Al, forming a mixed structure rather than a core-shell. If the time is too long: it may cause Al to be excessively deformed / cold-welded to form large particles, and at the same time increase the risk of oxidation. If the ball milling speed is too fast or too slow, Al-coated TiC cannot be obtained. This is because the speed is too slow and the energy is insufficient, making it difficult for Al to plastically deform. If the speed is too fast, local overheating causes Al to adhere or partially melt, destroying the core-shell structure; it may even cause TiC to break or Al to oxidize. The same is true for the ball-to-material ratio. If it is too low, the grinding medium is insufficient and the coating efficiency is low. If it is too high, excessive impact causes TiC to break or Al to be excessively cold-welded.

[0020] In a preferred embodiment, the Al-coated TiC core-shell composite powder has a particle size of 0.8-1 μm. Ball milling under the above parameters not only forms the Al-coated TiC core-shell composite powder, but also ensures that the particle size of the Al-coated TiC core-shell composite powder is within the range of the present invention and has optimal dispersibility in the melt.

[0021] Preferably, the press forming method is hydraulic forming, the pressure of the hydraulic forming is 15-20 kN, and the holding time is 10-20 s. In the actual operation process, a TYA-600 hydraulic testing machine is used for hydraulic pressure.

[0022] In a preferred embodiment, the prefabricated block is a cylinder or a block with a size of 20-40 mm×10-80 mm and a height-to-diameter ratio of 0.5-2.

[0023] In the present invention, there are not too many restrictions on the shape of the prefabricated block, and simple cylindrical or square shapes are preferred. In order to facilitate the design of the die-casting mold and uniform stress distribution, there are no strict requirements for the size, but the height-to-diameter ratio is controlled between 0.5-2 as much as possible to avoid uneven density during pressing due to being too high. The preferred size is 20-40 mm in height and 10-80 mm in width, length or diameter. If the size is too small, it may increase the edge effect and affect the sintering consistency. If it is too large, it may cause uneven distribution of pressing pressure, requiring layered pressing or isostatic pressing assistance.

[0024] The addition of prefabricated blocks can avoid segregation caused by density differences; the direct reaction between TiC and the melt is isolated, and the strong exothermic reaction is decomposed into multiple mild reactions; the aluminum layer isolates: reduces the contact probability between TiC and Ce, reduces the burnout rate of Ce, controls the reaction path and suppresses Al4C3.

[0025] The preferred solution is to add the prefabricated blocks to the aluminum melt in two batches. This prevents the TiC layer in the bottom layer from sintering into agglomerates. Furthermore, since the reaction between TiC and Al is exothermic, adding the prefabricated blocks in two batches can prevent the coating layer from melting prematurely and failing due to excessive temperatures.

[0026] Preferably, the first holding period is 20-30 minutes, followed by another 2-5 minutes of holding under stirring at 2000-3000 rpm, preferably 2000-2500 rpm. This eliminates any possible secondary phase segregation in the refiner and promotes uniform distribution of chemical components in the melt.

[0027] During the first heat preservation process, keep it warm and let it stand for 20-30 minutes. During this process, the surface of the prefabricated block reacts with the aluminum liquid at the interface, and the generated TiAl3 gradually diffuses into the aluminum liquid. By stirring, TiAl3 and TiC are fully dispersed into the melt. If the prefabricated block is stirred directly without keeping warm first, the surface reaction of the prefabricated block is not fully carried out, and undissolved TiC particles are easily formed, resulting in component segregation. If the stirring time is too long, the TiAl3 and TiC particles will be mechanically broken into nanometer scale, and the nucleation ability will be lost. If the stirring time is too short, the TiAl3 and TiC cannot be fully dispersed. If the stirring speed is too slow, the TiAl3 and TiC will also be fully dispersed. If the stirring speed is too fast, the refined phase may be destroyed.

[0028] Preferably, the second heat preservation process is first held for 20-30 minutes, and then stirred at 2000-3000 rpm, preferably 2000-2500 rpm, for 2-5 minutes. During the second heat preservation process, the mixture is first held at room temperature to allow Ce and AlTi3 to fully react, and then stirred at high speed to refine and fully disperse the resulting phase.

[0029] In the preferred embodiment, the deslagging refining process is to first skim the melt clean and then add carbon hexachloride for deslagging refining. Adding C2Cl6 to the aluminum melt for degassing refining will cause C2Cl6 to decompose and produce gas. The small amount of Cl2 and C2Cl6 gas produced is not soluble in the aluminum melt.

[0030] In a preferred embodiment, the mold is a graphite mold; the mold is preheated to 100-200°C before pouring, and the mold is water-cooled after pouring. Water cooling can suppress Ce segregation and prevent the growth of Al-Ce and Al3Ti phases.

[0031] In a preferred embodiment, the mass fraction of Ce in the Al-Ti-C-Ce master alloy is 0.25-1%, preferably 0.25-0.5%. Experiments have shown that the mass fraction of Ce has a significant impact on the final refinement effect, and the refinement effect is optimal within this range.

[0032] In a preferred embodiment, the Al-Ti-C-Ce master alloy has the following composition by mass percentage: Ti: 5%, C: 1.2%, Ce: 0.25-0.5%, and the balance is Al.

[0033] Further preferably, the Al-Ti-C-Ce master alloy has the following composition, in mass percentage: Ti: 5%, C: 1.2%, Ce: 0.5%, and the balance is Al.

[0034] In a preferred solution, the inevitable impurity content in the Al-Ti-C-Ce master alloy is ≤0.15%.

[0035] The present invention also provides an Al-Ti-C-Ce master alloy prepared by the above preparation method.

[0036] In a preferred embodiment, the Al-Ti-C-Ce master alloy contains a refined nucleation phase, wherein the refined nucleation phase comprises TiC, Al3Ti, Al 20 Ti2Ce.

[0037] The present invention also provides the application of the Al-Ti-C-Ce master alloy prepared by the above preparation method, and uses the Al-Ti-C-Ce master alloy as a refiner for aluminum-silicon alloy.

[0038] Furthermore, the amount of Al-Ti-C-Ce master alloy used is 0.5-1 wt.% of the aluminum-silicon alloy.

[0039] Furthermore, the aluminum silicon alloy is A356 alloy.

[0040] The present invention has the following beneficial effects:

[0041] 1. The preparation method of the present invention reasonably controls the addition amounts of titanium, carbon, and cerium elements, and replaces the Ti and C sources with TiC. No strong exothermic reaction is required to synthesize TiC on-site, thus avoiding the intense heat release of titanium powder + graphite. The traditional process suffers from local overheating of 1500°C, which leads to crucible erosion and component segregation. The 740°C temperature field of the TiC process is much more stable, and the direct addition of TiC reduces the generation of Al4C3. In the traditional process, titanium powder is flammable and explosive (ignition energy <10mJ), while TiC is much safer. The TiC solution avoids the generation of graphite dust (inhalable particulate matter) and CO (greenhouse gas), which is in line with the trend of green manufacturing.

[0042] 2. The preparation method of the present invention does not require complex equipment or high temperature and high pressure conditions, and has a simple process, low cost, significant refinement effect, and is environmentally friendly.

[0043] 3. Compared with the traditional fluoride salt reaction, the preparation method of the present invention does not emit harmful gases such as HF and Cl2, and uses an aluminum-cerium master alloy to avoid the introduction of other impurities.

[0044] 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

[0045] Figure 1 The XRD patterns of the master alloys prepared in Example 1 and Comparative Example 1 are shown in FIG. Figure 1 (a) is the XRD pattern of the Al-Ti-C-Ce master alloy prepared in Example 1. Figure 1 (b) is the XRD pattern of the Al-Ti-C master alloy prepared in Comparative Example 1.

[0046] Figure 2 The microstructure diagram of the master alloy of Example 1 and Comparative Example 1 is shown in FIG. Figure 2 (a) is the microstructure of the Al-Ti-C-Ce master alloy prepared in Example 1. Figure 2 (b) is the microstructure of the Al-Ti-C master alloy prepared in Comparative Example 1.

[0047] Figure 3 This is the grain macrograph of A356 alloy without adding refiner.

[0048] Figure 4 This is a macroscopic image of the grains of the A356 alloy after being refined by the refiner in Example 1.

[0049] Figure 5 This is a macroscopic image of the grains of the A356 alloy after being refined by the refiner in Comparative Example 1.

[0050] Figure 6 This is a macroscopic image of the grains of the A356 alloy after being refined by the refiner in comparative example 2.

[0051] Figure 7 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0052] 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.

[0053] Example 1

[0054] An Al-Ti-C-Ce master alloy comprises the following components, calculated by mass percentage: 5% titanium, 1.2% carbon, 0.5% cerium, an impurity content of ≤0.1%, and the balance being aluminum.

[0055] The preparation method thereof comprises the following steps:

[0056] Step 1: Dry titanium carbide powder with a particle size of 1.0-2.0 μm in a vacuum oven at 200°C for 2 hours. Mix with 45-75 μm aluminum powder in a ratio of TiC:Al=1:3 and ball mill the powder at 200 r / min for 60 minutes. The ball-to-powder ratio is controlled at 12:1, and the grinding balls are made of WC-Co. After ball milling, a core-shell structure composite powder with an Al-coated TiC with a particle size of 0.8-1 μm is obtained. The powder is then hydroformed to obtain a cylindrical prefabricated block with a size of 20×15 mm.

[0057] Step 2: Place the pure aluminum ingot in a graphite crucible and heat to 850°C until completely melted. Then, press the prefabricated blocks from Step 1 into the bottom of the melt in two batches through a graphite bell jar to prevent floating. Hold the mixture under argon for 25 minutes, then stir at 2500 rpm for another 3 minutes.

[0058] Step 3: Cool down to 750℃ and directly add Al-30Ce alloy block, keep warm for 25 minutes, and then keep warm for 4 minutes under stirring at 2500r / min.

[0059] Step 4: After skimming the melt, add carbon hexachloride for deslagging and refining, then quickly pour it into a mold and cool it to obtain an Al-Ti-C-Ce master alloy.

[0060] Example 2

[0061] An Al-Ti-C-Ce master alloy refiner comprises the following components, measured in percentage by mass: 5% titanium, 1.2% carbon, 0.25% cerium, an impurity content of ≤0.15%, and the balance being aluminum.

[0062] The preparation method thereof comprises the following steps:

[0063] Step 1: Dry titanium carbide powder with a particle size of 1.0-2.0 μm in a vacuum oven at 200°C for 2 hours. Mix with 45-75 μm aluminum powder in a ratio of TiC:Al=1:3 and ball mill the powder at 150 r / min for 60 minutes. The ball-to-powder ratio is controlled at 10:1, and the grinding balls are made of WC-Co. After ball milling, a core-shell structure composite powder with an Al-coated TiC with a particle size of 0.8-1 μm is obtained. The powder is then hydroformed to obtain a cylindrical prefabricated block with a size of 20×30 mm.

[0064] Step 2: Place the pure aluminum ingot in a graphite crucible and heat to 850°C until completely melted. Then, press the prefabricated blocks from Step 1 into the bottom of the melt in two batches through a graphite bell jar to prevent floating. Hold the mixture under argon for 20 minutes, then stir at 2000 rpm for another 2 minutes.

[0065] Step 3: Cool down to 750℃ and directly add Al-30Ce alloy block, keep warm for 20 minutes, and then keep warm for 2 minutes under stirring at 2000 r / min.

[0066] Step 4: After skimming the melt, add carbon hexachloride for deslagging and refining, then quickly pour it into a mold and cool it to obtain an Al-Ti-C-Ce master alloy refiner.

[0067] Example 3

[0068] An Al-Ti-C-Ce master alloy refiner comprises the following components, measured in percentage by mass: 5% titanium, 1.2% carbon, 1.0% cerium, an impurity content of ≤0.15%, and the balance being aluminum.

[0069] The preparation method thereof comprises the following steps:

[0070] Step 1: Dry titanium carbide powder with a particle size of 1.0-2.0 μm in a vacuum oven at 200°C for 2 hours. Mix with 45-75 μm aluminum powder in a ratio of TiC:Al=1:3, and ball mill the powder at 250 r / min for 60 minutes. The ball-to-powder ratio is controlled at 15:1, and the grinding balls are made of WC-Co. After ball milling, a core-shell structure composite powder with an Al-coated TiC with a particle size of 0.8-1 μm is obtained. It is then hydroformed to obtain a cylindrical prefabricated block with a size of 25×40 mm.

[0071] Step 2: Place the pure aluminum ingot in a graphite crucible and heat to 850°C until completely melted. Then, press the prefabricated blocks from Step 1 into the bottom of the melt in two batches through a graphite bell jar to prevent floating. Hold the mixture under argon for 30 minutes, then stir at 3000 rpm for another 5 minutes.

[0072] Step 3: Cool down to 750℃ and directly add Al-30Ce alloy block, keep warm for 30 min, and then keep warm for 5 min under stirring at 3000 r / min.

[0073] Step 4: After skimming the melt, add carbon hexachloride for deslagging and refining, then quickly pour it into a mold and cool it to obtain an Al-Ti-C-Ce master alloy refiner.

[0074] Comparative Example 1

[0075] An Al-Ti-C master alloy refiner comprises the following components by mass percentage: 5% titanium, 1.2% carbon, ≤0.1% impurity content, and the balance being aluminum. The preparation method thereof differs from that of Example 1 in that no aluminum-cerium alloy is added in step 3.

[0076] Comparative Example 2

[0077] An Al-Ti-C-Ce master alloy refiner comprises the following components, measured in percentage by mass: 5% titanium, 1.2% carbon, 0.5% cerium, ≤0.1% impurity content, and the balance being aluminum. The preparation method differs from that of Example 1 in that titanium powder and graphite are used in place of titanium carbide as the titanium source and carbon source in step 1.

[0078] Comparative Example 3

[0079] An Al-Ti-C-Ce master alloy refiner comprises the following components, measured in percentage by mass: 5% titanium, 1.2% carbon, 0.5% cerium, an impurity content ≤0.1%, and the balance being aluminum. The preparation method thereof differs from that of Example 1 in that, in step 1, no ball milling is performed but the alloys are simply mixed and pressed into a prefabricated block.

[0080] Comparative Example 4

[0081] An Al-Ti-C-Ce master alloy refiner comprises the following components, in percentage by mass: 5% titanium, 1.2% carbon, 0.5% cerium, an impurity content ≤0.1%, and the balance being aluminum. The preparation method thereof differs from that of Example 1 in that, in step 1, the Al:TiC ratio is 1:1 and ball milling is performed.

[0082] Performance Analysis 1

[0083] (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. The results are as follows: Figure 1 As shown, the phase composition of the refiner in Example 1 is α-Al, TiC, Al3Ti, Al 20 Ti2Ce phase.

[0084] (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 As shown, Figure 2 (a) is the microstructure of the Al-Ti-C-Ce master alloy prepared in Example 1, and (b) is the microstructure of the Al-Ti-C master alloy in Comparative Example 1.

[0085] Depend on Figure 2 It can be seen that the refiners of Example 1 and Comparative Example 1 have uniform structures, the sizes of refined nucleation particles Al3Ti are 8-10 μm and 20-30 μm respectively, and the size of TiC particles is less than 2-3 μm.

[0086] Performance Analysis 2

[0087] (1) The prepared Al-Ti-C-Ce and Al-Ti-C master alloy ingots of Examples 1-3 and Comparative Examples 1-4 were crushed and then ball-milled in a planetary ball mill with a ball-to-material ratio of 10:1 and a rotation speed of 300 rpm for 10 hours. 0.5% ethanol was added to prevent cold welding.

[0088] (2) Weigh the aluminum-silicon A356 alloy into a clay crucible and place it in a crucible resistance furnace at a temperature of 750°C to make it into a molten state; then weigh the refiner after ball milling in (1) according to 0.2% of the mass of the molten aluminum-silicon alloy, add the refiner to the molten aluminum-silicon alloy and keep it warm for 15-300 minutes; then take the crucible out of the furnace, stir the melt thoroughly, and then pour it into a cast iron mold, cool and demold it, and obtain the refined A356 alloy ingot.

[0089] The grain macroscopic images of the original A356 alloy and the refined A356 alloy ingot are shown in Figure 2. Figures 3-5 As shown, Figure 3 It is an aluminum-silicon alloy without adding refiner. Figure 4This is the macroscopic image of the grains of the aluminum-silicon alloy obtained by adding the Al-Ti-C-Ce master alloy in Example 1 at different holding times. Figure 5 This is the grain macrograph of the aluminum-silicon alloy obtained by adding the Al-Ti-C master alloy in Comparative Example 1 at different holding times. Figure 6 The macroscopic images of the grains of the aluminum-silicon alloy obtained by adding the Al-Ti-C-Ce master alloy in Comparative Example 2 at different holding times are shown. Figure 3 It can be seen that the average grain size of the original A356 alloy is more than 1200 μm. Figure 4 It can be seen that the grain size of the Al-Ti-C-Ce master alloy in Example 1 was refined to 95 μm after 15 min of heat preservation. Figure 4 、 Figure 5 、 Figure 6 It can be seen that the average grain size of the A356 alloy ingot after refinement by the refiners of Example 1, Comparative Example 1 and Comparative Example 2 after 300 minutes of holding is reduced to below 106 μm, 278 μm and 141 μm, respectively, which are 8.83%, 23.17% and 11.75% of the original A356 alloy, respectively. This shows that compared with the refiners without rare earth cerium and with titanium source and cerium source respectively, the Al-Ti-C-Ce refiner prepared in Example 1 with TiC as raw material can more effectively improve the grain structure of the aluminum silicon alloy. In addition, the Al-Ti-C-Ce refiner obtained in Example 2 reduces the grain size of the A356 alloy to below 118 microns after 300 minutes of holding, which is an improvement of the A356 aluminum silicon alloy. The Al-Ti-C-Ce refiner prepared in Example 3 reduces the grain size of the A356 alloy to less than 128 μm after holding for 300 min, which is 10.67% of the original grain size of the A356 aluminum-silicon alloy. The Al-Ti-C-Ce refiner prepared in Comparative Example 3 reduces the grain size of the A356 alloy to less than 227 μm after holding for 300 min, which is 18.92% of the original grain size of the A356 aluminum-silicon alloy. The Al-Ti-C-Ce refiner prepared in Comparative Example 4 reduces the grain size of the A356 alloy to less than 171 μm after holding for 300 min, which is 14.25% of the original grain size of the A356 aluminum-silicon alloy.

[0090] 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 method for preparing an Al-Ti-C-Ce master alloy using titanium carbide as a Ti source and a C source, characterized in that: Titanium carbide powder and aluminum powder are mixed and ball-milled to obtain a composite powder of a core-shell structure of Al-coated TiC, the composite powder of the core-shell structure of Al-coated TiC is pressed into shape to obtain a prefabricated block, the prefabricated blocks are pressed into the bottom of the aluminum melt in batches through a graphite bell jar, and the prefabricated blocks are first kept warm at 760-850°C, then cooled to 700-750°C, and then Al-30Ce master alloy is added, and the prefabricated blocks are kept warm for a second time, followed by deslagging and refining, and then poured into a mold to obtain the Al-Ti-C-C master alloy; The Al-Ti-C-Ce master alloy has the following composition by mass percentage: Ti: 0.5-7%, C: 0.5-2%, Ce: 0.05-1%, and the balance is Al.

2. The method for preparing an Al-Ti-C-Ce master alloy using titanium carbide as a Ti source and a C source according to claim 1, characterized in that: The particle size of the titanium carbide powder is 1.0-2.0 μm, and the particle size of the aluminum powder is 45-75 μm; The titanium carbide powder is first dried in a vacuum environment at 100-200°C for 2-4 hours with a vacuum degree of ≤10 -2 Pa.

3. The method for preparing an Al-Ti-C-Ce master alloy using titanium carbide as a Ti source and a C source according to claim 1, characterized in that: In the Al-coated TiC core-shell structure composite powder, the mass ratio of TiC:Al is 1:2-4; The ball mill has a rotation speed of 150-250 r / min, a ball milling time of 30-60 min, a ball-to-material ratio of 10-15:1, and a grinding ball material of WC-Co; The particle size of the Al-coated TiC core-shell structure composite powder is 0.8-1 μm.

4. The method for preparing an Al-Ti-C-Ce master alloy using titanium carbide as a Ti source and a C source according to claim 1, characterized in that: The pressing method is hydraulic forming, the pressure of the hydraulic forming is 15-20 kN, and the holding time is 10-20 s; The prefabricated block is a cylinder or a block with a size of 20-40 mm×10-80 mm and a height-to-diameter ratio of 0.5-2.

5. The method for preparing an Al-Ti-C-Ce master alloy using titanium carbide as a Ti source and a C source according to claim 1, characterized in that: The preforms were added to the aluminum melt in two batches; During the first heat preservation process, the mixture is first kept warm for 20-30 minutes, and then kept warm for 2-5 minutes under stirring at a rate of 2000-3000 r / min; During the second heat preservation process, the mixture is first kept warm for 20-30 minutes, and then kept warm for 2-5 minutes under stirring at a rate of 2000-3000 r / min.

6. The method for preparing an Al-Ti-C-Ce master alloy using titanium carbide as a Ti source and a C source according to claim 1, characterized in that: The deslagging and refining process is to first skim the melt cleanly and then add carbon hexachloride to carry out deslagging and refining.

7. The method for preparing an Al-Ti-C-Ce master alloy using titanium carbide as a Ti source and a C source according to claim 1, characterized in that: The mold is a graphite mold; the mold is preheated to 100-200° C. before pouring, and the mold is water-cooled after pouring into the mold.

8. The method for preparing an Al-Ti-C-Ce master alloy using titanium carbide as a Ti source and a C source according to claim 1, characterized in that: In the Al-Ti-C-Ce master alloy, the mass fraction of Ce is 0.25-1%.

9. The Al-Ti-C-Ce master alloy prepared by the method for preparing an Al-Ti-C-Ce master alloy using titanium carbide as a Ti source and a C source according to any one of claims 1 to 8, characterized in that: The Al-Ti-C-Ce master alloy contains a refined nucleation phase, which includes TiC, Al3Ti, Al 20 Ti2Ce.

10. Use of an Al-Ti-C-Ce master alloy prepared by the method for preparing an Al-Ti-C-Ce master alloy using titanium carbide as a Ti source and a C source according to any one of claims 1 to 8, characterized in that: Al-Ti-C-Ce master alloy is used as a refiner for aluminum-silicon alloy.

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