Al-Cr-Ce grain refiner, and preparation method and application thereof

Abstract

The application discloses an Al-Cr-Ce grain refiner and a preparation method and application thereof, and belongs to the technical field of metal material processing. The Al-Cr-Ce grain refiner comprises 1-3.6% of Cr, 3-6% of Ce, <0.1% of inevitable impurities and the balance of Al according to mass percentage, wherein the mass ratio of Cr to Ce is 0.3:1-1:1. The Al-Cr-Ce grain refiner can be applied to cast aluminum-silicon hypoeutectic alloy, the adding amount is 0.5-5.0%, the alpha-Al crystal grains and eutectic silicon can be refined, the Fe-rich phase in the alloy is changed from needle-shaped into fishbone-shaped or square-shaped and Chinese character-shaped, the "silicon poisoning" problem of the traditional refiner is effectively overcome, and the morphology of the Fe-rich phase is controlled.

Description

Technical Field

[0001] This invention belongs to the field of metal material processing technology, specifically relating to an Al-Cr-Ce grain refiner, its preparation method, and its application. Background Technology

[0002] Cast aluminum-silicon hypoeutectic alloys are widely used in automotive engines, aerospace components, and electronic packaging housings due to their excellent casting properties, high specific strength, good wear resistance, and corrosion resistance. Statistics show that aluminum-silicon alloys account for more than 80% of global aluminum casting production.

[0003] The mechanical properties of aluminum alloy castings are closely related to their grain size. Refining α-Al grains not only improves the strength and plasticity of the alloy but also reduces elemental segregation and casting defects such as shrinkage porosity and hot cracking. Adding grain refiners to the molten aluminum alloy to improve its microstructure and properties is an important process in aluminum alloy casting production. Currently, the most commonly used grain refiners in industry are Al-Ti-B and Al-Ti-C master alloys, which have excellent refining effects in pure aluminum and wrought aluminum alloys. However, in cast aluminum-silicon alloys with high silicon content, especially when the silicon content is greater than 5%, traditional Al-Ti-B and Al-Ti-C grain refiners suffer from "silicon poisoning." The Si element in the alloy reacts with TiB2 and TiC particles, leading to a decline in the nucleation ability of the grain refiner, or even its failure.

[0004] In recent years, researchers have developed novel grain refiners such as Al-Ti-B-RE, Al-Ti-C-RE, and Al-Ti-Nb-B, which have alleviated the "silicon poisoning" problem to some extent. However, the preparation processes of these grain refiners are relatively complex, requiring high levels of process control and increasing production costs. Furthermore, cast aluminum-silicon alloys inevitably contain Fe, especially given the increasing use of recycled aluminum. Fe typically exists as a acicular, Fe-rich phase, which severely disrupts the matrix and reduces the alloy's plasticity and fatigue properties. Existing grain refiners primarily address the α-Al grain refinement problem, with limited effect on controlling the morphology of the Fe-rich phase.

[0005] Therefore, developing a low-addition, high-efficiency grain refiner that can effectively refine α-Al grains in cast aluminum-silicon hypoeutectic alloys and simultaneously control the morphology of Fe-rich phases has significant industrial application value. Summary of the Invention

[0006] One objective of this invention is to provide an Al-Cr-Ce grain refiner; another objective is to provide a method for preparing the Al-Cr-Ce grain refiner; and a third objective is to provide the application of the Al-Cr-Ce grain refiner in cast aluminum-silicon hypoeutectic alloys or cast aluminum-silicon hypoeutectic alloys containing Fe.

[0007] This invention provides the following technical solution:

[0008] An Al-Cr-Ce grain refiner, comprising, by mass percentage, 1-3.6% Cr, 3-6% Ce, <0.1% unavoidable impurities, and the balance aluminum.

[0009] Furthermore, the mass ratio of Cr to Ce ranges from 0.3:1 to 1:1.

[0010] Furthermore, the phases of the Al-Cr-Ce grain refiner include an α-Al matrix and second-phase particles dispersed in the α-Al matrix; the second-phase particles include Al-Cr-Ce ternary intermetallic compounds and Al-Ce binary intermetallic compounds.

[0011] Furthermore, the Al-Cr-Ce ternary intermetallic compound is Cr2Al 20 The Ce phase is formed in situ, has a blocky crystal morphology, a grain size of 15 μm to 40 μm, and is dispersed in the α-Al matrix.

[0012] This invention also provides a method for preparing an Al-Cr-Ce grain refiner, comprising the following steps:

[0013] (1) Smelting of Al-Cr-Ce grain refiner: Pure aluminum and Cr source are placed in a graphite crucible and placed in a smelting furnace. Argon gas is used for protection throughout the process, and the temperature is raised to 700~800°C. After the raw materials are melted, they are stirred thoroughly, and Ce source is added. The temperature is raised to 900-1050°C and held for 30-40 minutes. During the holding process, the melt is stirred for no less than 30 seconds within 10 minutes to obtain Al-Cr-Ce alloy melt.

[0014] (2) Casting of Al-Cr-Ce grain refiner: The Al-Cr-Ce alloy melt prepared in step (1) is cooled to 750~850℃, and C2Cl6 refining agent is added for refining. After removing the surface slag, it is cast into a preheated steel mold and cooled to obtain Al-Cr-Ce grain refiner.

[0015] Furthermore, the Cr source is an Al-Cr master alloy or pure Cr, and the Ce source is an Al-Ce master alloy.

[0016] Further, when the Cr source is an Al-Cr master alloy, the mass percentage of the Al-10Cr master alloy is 10%~36%, the mass percentage of the Al-10Ce master alloy is 30%~60%, and the balance is pure aluminum; when the Cr source is pure Cr, the mass percentage of the pure Cr is 1%~3.6%, the mass percentage of the Al-10Ce master alloy is 30%~60%, and the balance is pure aluminum; so that the specific values ​​of the three ultimately satisfy the following: the Cr content in the grain refiner is 1%~3.6%, the Ce content is 3%~6%, and the Cr / Ce mass ratio is between 0.3:1 and 1:1; the mass ratio of the C2Cl6 refining agent added is approximately 0.5%~1% of the total Al-Cr-Ce alloy.

[0017] Furthermore, the preheating temperature of the steel mold is 200-250℃.

[0018] Furthermore, the present invention also provides the application of the Al-Cr-Ce grain refiner in cast aluminum-silicon hypoeutectic alloys or cast aluminum-silicon hypoeutectic alloys containing Fe.

[0019] Furthermore, the amount of Al-Cr-Ce grain refiner added is 0.5~5% of the total mass of the aluminum-silicon alloy.

[0020] When the Al-Cr-Ce grain refiner is used in cast aluminum-silicon hypoeutectic alloys or cast aluminum-silicon hypoeutectic alloys containing Fe, it can refine α-Al grains and eutectic silicon, and transform the Fe-rich phase in the alloy from needle-like and lamellar to fishbone-like, block-like, or Chinese character-like.

[0021] Compared with the prior art, the Al-Cr-Ce grain refiner provided by the present invention is prepared by melt in-situ reaction method to produce Cr2Al dispersed in the α-Al matrix. 20 Intermetallic compounds such as Ce. Cr2Al 20 Second-phase particles such as Ce are generated directly and in situ in the aluminum melt, resulting in a clean interface and good bonding with the aluminum matrix. The particles are also uniformly dispersed and exhibit excellent chemical stability in the aluminum-silicon alloy melt, resisting reaction with Si and effectively avoiding the "silicon poisoning" problem of traditional Al-Ti-B grain refiners in aluminum-silicon alloys. Simultaneously, for iron-containing aluminum-silicon hypoeutectic alloys, Cr and Ce elements can simultaneously transform the harmful acicular and flaky Fe-rich phases into fishbone-like, blocky, or Chinese character-like structures, significantly reducing the cutting effect of Fe-rich phases on the matrix. Furthermore, this grain refiner can be prepared using Al-Cr master alloys, Al-Ce master alloys, or pure Cr as raw materials in conventional smelting equipment, resulting in a simple and low-cost process suitable for large-scale industrial production. Attached Figure Description

[0022] Figure 1The XRD pattern of the Al-3.2Cr-4.3Ce refining agent in Example 1 of this invention;

[0023] Figure 2 The images show the SEM image (a) and EDS spectrum (be) of the Al-3.2Cr-4.3Ce refining agent in Example 1 of this invention.

[0024] Figure 3 The metallographic characterization results are for the Al-7Si alloy without the addition of refining agent in Comparative Example 1.

[0025] Figure 4 Metallographic characterization results of Al-7Si alloy after adding Al-3.2Cr-4.3Ce refining agent according to the present invention;

[0026] Figure 5 The image shows the metallographic characterization results of the Al-7Si-0.4Fe alloy after adding the Al-3.2Cr-4.3Ce refining agent of this invention. Detailed Implementation

[0027] Example 1

[0028] An Al-Cr-Ce grain refiner (Al-3.2Cr-4.3Ce grain refiner), by mass percentage, comprises 3.20% Cr, 4.3% Ce, <0.1% unavoidable impurities, and the balance being aluminum (Al), wherein the mass ratio of Cr to Ce is approximately 0.74:1. The specific preparation method includes the following steps:

[0029] (1) Preparation of raw materials: Al-10Cr master alloy (particle size less than 3mm) is used as Cr source, Al-10Ce master alloy (composed of aluminum solid solution α-Al matrix and Al-Ce binary phase, the Al-Ce binary phase has needle-like morphology and an average size of 8.5μm. The Al-10Ce master alloy is made by melting and casting 99.9% pure Ce and 99.9% pure Al ingots at 850℃) as Ce source, and pure aluminum ingots (purity ≥99.9%) as Al source. Based on the above composition (including 3.20% Cr, 4.3% Ce, <0.1% unavoidable impurities, and the balance being aluminum), 48.00g of Al-10Cr master alloy, 64.50g of Al-10Ce master alloy, and 37.50g of pure aluminum ingot were weighed as raw materials, with a total batching amount of 150g. Among them, pure Cr particles and Al-10Ce master alloy were additionally weighed as burn-off, based on a Cr and Ce recovery rate of 95%.

[0030] (2) Smelting of Al-Cr-Ce: First, pure aluminum ingots are melted in a graphite crucible and heated to 760°C. Then, Al-10Cr master alloy is added. After it is completely melted, it is stirred thoroughly. Then, Al-10Ce master alloy is added to the aluminum melt, and the temperature is raised to 950°C and held for 35 minutes. During the holding process, it is stirred for 30 seconds every 10 minutes to obtain a uniform Al-3.20Cr-4.3Ce alloy melt.

[0031] (3) Casting of Al-Cr-Ce grain refiner: The Al-3.20Cr-4.3Ce alloy melt prepared above is cooled to 800℃, and 0.3% of C2Cl6 refining agent is added to the melt for refining. After removing the surface slag, it is cast into a steel mold preheated to 250℃. After solidification and cooling, it is demolded to obtain Al-3.20Cr-4.3Ce alloy, which is the Al-Cr-Ce grain refiner for casting aluminum-silicon hypoeutectic alloy.

[0032] The Al-3.20Cr-4.3Ce refining agent prepared above consists of an aluminum solid solution α-Al matrix and second-phase particles dispersed in the matrix. The second-phase particles include Cr2Al. 20 Ce ternary intermetallic compounds, as well as Al-Cr binary intermetallic compounds and Al-Ce binary intermetallic compounds; among them, Cr2Al 20 The Ce phase exhibits a cubic or blocky crystal morphology with an average grain size of 25.7 μm, and is diffusely distributed within the α-Al matrix.

[0033] X-ray diffraction analysis was performed on the Al-Cr-Ce refining agent prepared in Example 1, and the results are as follows: Figure 1 As shown. From Figure 1 It can be seen that the phase composition of this refining agent mainly includes α-Al and Cr2Al. 20 Ce, Al 11 Ce3 indicates that the preparation method of this embodiment can prepare Cr2Al-containing compounds. 20 Ce is a refining agent for the second phase.

[0034] The Al-Cr-Ce refining agent prepared in Example 1 was characterized by scanning electron microscopy, and the results are as follows: Figure 2 As shown. From Figure 2 It can be seen that the Cr2Al in the Al-Cr-Ce grain refiner prepared in Example 1 20 The Ce second-phase particles are uniformly dispersed on the α-Al matrix, with a particle size of approximately 12~37 μm and an average particle size of approximately 25.7 μm. This indicates that the preparation method of Example 1 can be used to prepare an Al-Cr-Ce refiner with a uniform second-phase structure.

[0035] Example 2

[0036] An Al-Cr-Ce grain refiner (Al-3.51Cr-4.3Ce grain refiner), by mass percentage, comprises 3.51% Cr, 4.3% Ce, <0.1% unavoidable impurities, and the balance being aluminum (Al), wherein the mass ratio of Cr to Ce is approximately 0.82:1. The specific preparation method includes the following steps:

[0037] (1) Preparation of raw materials: Pure Cr (purity ≥ 99.8%, metal particles) is used as the Cr source, Al-10Ce master alloy (composed of aluminum solid solution α-Al matrix and Al-Ce binary phase, the Al-Ce binary phase has a needle-like morphology with an average size of 8.5μm, the Al-10Ce master alloy is made by melting and casting 99.9% pure Ce and 99.9% pure Al ingots at 850℃) as the Ce source, and pure aluminum ingots (purity ≥ 99.9%) as the Al source. Based on the above composition (including 3.51% Cr, 4.3% Ce, <0.1% unavoidable impurities, and the balance being aluminum), 5.27g of pure Cr, 64.50g of Al-10Ce master alloy, and 80.23g of pure aluminum ingot were weighed as raw materials, with a total feed amount of 150g. Among them, pure Cr and Al-10Ce master alloy were weighed separately as burn-off, based on a Cr and Ce recovery rate of 95%.

[0038] (2) Smelting of Al-Cr-Ce: First, pure aluminum ingots are melted in a graphite crucible and heated to 780°C. Then, pure Cr particles are added and stirred thoroughly after complete melting. Al-10Ce intermediate alloy is wrapped in aluminum foil and pressed into the aluminum melt. The temperature is raised to 980°C and held for 35 minutes. During the holding process, the mixture is stirred for 30 seconds every 10 minutes to obtain a uniform Al-3.51Cr-4.3Ce alloy melt.

[0039] (3) Casting of Al-Cr-Ce refining agent: The same casting steps as in Example 1 were used.

[0040] The Al-3.51Cr-4.3Ce refining agent prepared above consists of an aluminum solid solution α-Al matrix and second-phase particles dispersed in the matrix. The second-phase particles include Cr2Al. 20 Ce ternary intermetallic compounds, as well as Al-Cr binary intermetallic compounds and Al-Ce binary intermetallic compounds; among them, Cr2Al 20 The Ce phase exhibits a cubic or blocky crystal morphology with an average grain size of 45.8 μm, and is diffusely distributed within the α-Al matrix.

[0041] Example 3

[0042] An Al-Cr-Ce grain refiner (Al-2.39Cr-4.3Ce grain refiner), by mass percentage, comprises 2.39% Cr, 4.3% Ce, <0.1% unavoidable impurities, and the balance being aluminum (Al), wherein the mass ratio of Cr to Ce is 0.56:1. The specific preparation method includes the following steps:

[0043] (1) Preparation of raw materials: Al-10Cr master alloy is used as the Cr source, Al-10Ce master alloy as the Ce source, and pure aluminum ingot as the Al source. By mass percentage, according to the above composition (including 2.39% Cr, 4.3% Ce, <0.1% unavoidable impurities, and the balance being aluminum), 35.85g of Al-10Cr master alloy, 64.50g of Al-10Ce master alloy, and 49.65g of pure aluminum ingot are weighed as raw materials, with a total feed amount of 150g. Among them, Al-10Cr master alloy and Al-10Ce master alloy are weighed separately according to the Cr and Ce recovery rate of 95% as burn-off.

[0044] (2) Smelting of Al-Cr-Ce: The same smelting steps as in Example 2 were used.

[0045] (3) Casting of Al-Cr-Ce refining agent: The same casting steps as in Example 1 were used.

[0046] The Al-2.39Cr-4.3Ce refining agent prepared above consists of an aluminum solid solution α-Al matrix and second-phase particles dispersed in the matrix. The second-phase particles include Cr2Al. 20 Ce ternary intermetallic compounds, as well as Al-Cr binary intermetallic compounds and Al-Ce binary intermetallic compounds; among them, Cr2Al 20 The Ce phase exhibits a cubic or blocky crystal morphology with an average grain size of 29.4 μm, and is diffusely distributed within the α-Al matrix.

[0047] Example 4

[0048] An Al-Cr-Ce grain refiner (Al-1.60Cr-4.3Ce grain refiner), by mass percentage, comprises 1.60% Cr, 4.3% Ce, <0.1% unavoidable impurities, and the balance being aluminum (Al), wherein the mass ratio of Cr to Ce is approximately 0.37:1. The specific preparation method includes the following steps:

[0049] (1) Preparation of raw materials: Al-10Cr master alloy is used as the Cr source, Al-10Ce master alloy as the Ce source, and pure aluminum ingot as the Al source. By mass percentage, according to the above composition (including 1.60% Cr, 4.3% Ce, <0.1% unavoidable impurities, and the balance being aluminum), 24.00g of Al-10Cr master alloy, 64.50g of Al-10Ce master alloy, and 61.50g of pure aluminum ingot are weighed as raw materials, with a total feed amount of 150g. Among them, Al-10Cr master alloy and Al-10Ce master alloy are weighed separately according to the Cr and Ce recovery rate of 95% as burn-off.

[0050] (2) Smelting of Al-Cr-Ce: The same smelting steps as in Example 2 were used.

[0051] (3) Casting of Al-Cr-Ce refining agent: The same casting steps as in Example 1 were used.

[0052] The Al-1.60Cr-4.3Ce refining agent prepared above consists of an aluminum solid solution α-Al matrix and second-phase particles dispersed in the matrix. The second-phase particles include Cr2Al. 20 Ce ternary intermetallic compounds, as well as Al-Cr binary intermetallic compounds and Al-Ce binary intermetallic compounds; among them, Cr2Al 20 The Ce phase exhibits a cubic or blocky crystal morphology with an average grain size of 32.1 μm, and is diffusely distributed within the α-Al matrix.

[0053] Application effect test examples

[0054] Comparative Example 1

[0055] To directly compare with Application Example 1, which incorporates the Al-3.2Cr-4.3Ce grain refiner of Example 1 of this invention, this invention also prepared an Al-7Si alloy without the addition of the grain refiner to verify the grain refinement effect of the grain refiner of this invention on the α-Al grains of the Al-7Si alloy.

[0056] The specific preparation steps for the Al-7Si alloy without added refining agent are as follows:

[0057] (1) Alloy smelting: According to the chemical composition of Al-7Si alloy: Si 7.0%, the balance is Al, weigh out 200g of pure aluminum and Al-Si alloy intermediate alloy, put them into a graphite clay crucible, place them in a resistance furnace and heat them to 730℃.

[0058] (2) Heat preservation treatment: without adding any finer agent, heat at 730℃ for 15 minutes, and stir with a graphite rod once every 5 minutes during the period.

[0059] (3) Casting: After the heat preservation is completed, the melt is cast into an iron mold that has been preheated to 250°C.

[0060] (4) Sampling and analysis: After the casting solidifies and cools, it is demolded and cut from 20mm from the bottom. The cut surface is ground, polished and etched. The α-Al grain structure is observed using a polarizing microscope.

[0061] Results analysis:

[0062] In the Al-7Si alloy without added refining agents, the α-Al grains exhibit a coarse dendritic morphology, with an average grain size of approximately 915.8 μm (see [link to relevant documentation]). Figure 3 The grain size distribution is uneven, the dendrite arms are large, the dendrite spacing is wide, and there is obvious segregation.

[0063] Application Example 1

[0064] The Al-3.2Cr-4.3Ce grain refiner prepared in Example 1 was applied to the grain refinement treatment of cast aluminum-silicon hypoeutectic alloy (Al-7Si alloy). The specific steps are as follows:

[0065] (1) Alloy smelting: According to the chemical composition of Al-7Si alloy: Si 7.0%, the balance is Al, weigh out 200g of pure aluminum and Al-Si alloy intermediate alloy, put them into a graphite clay crucible, place them in a resistance furnace and heat them to 730℃.

[0066] (2) Refining treatment: The Al-3.2Cr-4.3Ce refining agent prepared in Example 1, accounting for 2% of the total mass of Al-7Si alloy, was wrapped in aluminum foil and pressed into the alloy melt, and stirred thoroughly with a graphite rod for 30 seconds.

[0067] (3) Heat preservation and casting: Heat preservation at 730℃ for 15 minutes, stirring once every 5 minutes during the period. After heat preservation, the melt is poured into an iron mold that has been preheated to 250℃.

[0068] (4) Sampling and analysis: After the casting solidifies and cools, it is demolded and cut from 20mm from the bottom. The cut surface is ground, polished and etched. The α-Al grain structure is observed using a polarizing microscope.

[0069] Results analysis:

[0070] After adding the Al-3.2Cr-4.3Ce refining agent prepared in Example 1, as... Figure 4As shown, the α-Al grains of the Al-7Si alloy are significantly refined, with an average grain size of approximately 151.5 μm, and the grain morphology changes from coarse dendrites to fine equiaxed grains. The results indicate that the Al-Cr-Ce grain refiner of this invention has a good grain refinement effect on the Al-7Si alloy.

[0071] Application Example 2

[0072] The Al-3.2Cr-4.3Ce grain refiner prepared in Example 1 was applied to the grain refinement and Fe-rich phase modification treatment of Fe-containing cast aluminum-silicon hypoeutectic alloy (Al-7Si-0.4Fe alloy). The specific steps are as follows:

[0073] (1) Alloy smelting: According to the chemical composition of Al-7Si-0.4Fe alloy: Si 7.0wt%, 0.4wt%, balance Al, weigh 200g of pure aluminum, pure iron (particle size about 3~4mm) and Al-Si alloy master alloy, put them into a graphite clay crucible, place them in a resistance furnace and heat them to 730℃.

[0074] (2) Refining treatment: The Al-3.2Cr-4.3Ce refining agent prepared in Example 1, which accounts for 2% of the total mass of Al-7Si-0.4Fe alloy, is wrapped in aluminum foil and pressed into the alloy melt. It is then stirred thoroughly with a graphite rod for 30 seconds.

[0075] (3) Heat preservation and casting: Heat preservation at 730℃ for 15 minutes, stirring once every 5 minutes during the period. After heat preservation, the melt is poured into an iron mold that has been preheated to 250℃.

[0076] (4) Sampling and analysis: After the casting solidifies and cools, it is demolded and cut from 20 mm from the bottom. The cut surface is ground, polished and etched. The α-Al grain structure is observed with a polarizing microscope and the morphology of the Fe-rich phase is observed with a scanning electron microscope (SEM).

[0077] Results analysis:

[0078] After adding the Al-3.2Cr-4.3Ce grain refiner prepared in Example 1, the α-Al grains of the Al-7Si-0.4Fe alloy were significantly refined, with an average grain size of approximately 161.7 μm. Meanwhile, as... Figure 5 As shown, the Fe-rich phase in the alloy transforms from its original coarse needle-like shape to a blocky or Chinese character-like shape, with a significantly reduced size, thus significantly reducing its cutting effect on the matrix. The results indicate that the Al-Cr-Ce grain refiner of this invention can not only refine α-Al grains but also effectively modify the morphology of the Fe-rich phase in Fe-containing aluminum-silicon hypoeutectic alloys.

[0079] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. All equivalent substitutions, modifications, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An Al-Cr-Ce grain refiner, characterized in that, The Al-Cr-Ce grain refiner comprises, by mass percentage, 1-3.6% Cr, 3-6% Ce, <0.1% unavoidable impurities, and the balance aluminum.

2. The Al-Cr-Ce grain refiner according to claim 1, characterized in that, The mass ratio of Cr to Ce ranges from 0.3:1 to 1:

1.

3. The Al-Cr-Ce grain refiner according to claim 1, characterized in that, The phases of the Al-Cr-Ce grain refiner include an α-Al matrix and second-phase particles dispersed in the α-Al matrix; the second-phase particles include Al-Cr-Ce ternary intermetallic compounds and Al-Ce binary intermetallic compounds.

4. The Al-Cr-Ce grain refiner according to claim 3, characterized in that, The Al-Cr-Ce ternary intermetallic compound is Cr2Al 20 The Ce phase is formed in situ, has a blocky crystal morphology, a grain size of 15 μm to 40 μm, and is dispersed in the α-Al matrix.

5. A method for preparing an Al-Cr-Ce grain refiner, characterized in that, The preparation method includes the following steps: (1) Smelting of Al-Cr-Ce grain refiner: Pure aluminum and Cr source are placed in a graphite crucible and placed in a smelting furnace. Argon gas is used for protection throughout the process, and the temperature is raised to 700~800°C. After the raw materials are melted, they are stirred thoroughly, and Ce source is added. The temperature is raised to 900-1050°C and held for 30-40 minutes. During the holding process, the melt is stirred for no less than 30 seconds within 10 minutes to obtain Al-Cr-Ce alloy melt. (2) Casting of Al-Cr-Ce grain refiner: The Al-Cr-Ce alloy melt prepared in step (1) is cooled to 750~850℃, and C2Cl6 refining agent is added for refining. After removing the surface slag, it is cast into a preheated steel mold and cooled to obtain Al-Cr-Ce grain refiner.

6. The preparation method according to claim 5, characterized in that, The Cr source is an Al-Cr master alloy or pure Cr, and the Ce source is an Al-Ce master alloy.

7. The preparation method according to claim 6, characterized in that, When the Cr source is an Al-Cr master alloy, the mass percentage of the Al-10Cr master alloy is 10%~36%, the mass percentage of the Al-10Ce master alloy is 30%~60%, and the balance is pure aluminum; when the Cr source is pure Cr, the mass percentage of the pure Cr is 1%~3.6%, the mass percentage of the Al-10Ce master alloy is 30%~60%, and the balance is pure aluminum; the mass ratio of the C2Cl6 refining agent added is approximately 0.5%~1% of the total Al-Cr-Ce alloy.

8. The preparation method according to claim 5, characterized in that, The preheating temperature of the steel mold is 200-250℃.

9. The application of the Al-Cr-Ce grain refiner according to any one of claims 1 to 4 in cast aluminum-silicon hypoeutectic alloys.

10. The application according to claim 9, characterized in that, The amount of Al-Cr-Ce grain refiner added is 0.5-5% of the total mass of the aluminum-silicon alloy.

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