La-containing aluminum alloy and preparation method thereof

Abstract

The invention discloses an aluminum alloy containing a La element and a preparation method thereof. The method comprises the following steps: preparing an aluminum alloy melt; the aluminum alloy melt is subjected to ultrasonic treatment, then a grain refiner is added, heat preservation and pouring are conducted, and an aluminum alloy cast ingot is obtained; the aluminum alloy cast ingot is heated for homogenization treatment; and carrying out hot extrusion and aging treatment on the homogenized aluminum alloy ingot. The mechanical strength of the aluminum alloy can be effectively improved, and the use performance of the aluminum alloy is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and in particular to an aluminum alloy containing La and a preparation method thereof. Background Art

[0002] Aluminum alloy is a lightweight, well-processed metal material widely used in construction, transportation, and electromechanical applications. Al-Mg-Si alloys are aluminum alloys with silicon and magnesium as the primary alloying elements, forming a Mg2Si strengthening phase. They exhibit excellent strength and corrosion resistance, meeting the requirements for lightweighting in automobiles and are commonly used as automotive component materials. With the development of the automotive industry, the performance requirements for aluminum alloys used in automotive components have gradually increased. Improving the strength of aluminum alloys can reduce the wear and tear of related components during vehicle use, thereby improving vehicle safety and service life. Therefore, improving the manufacturing technology of aluminum alloys to enhance their strength has become an important research topic for aluminum alloys used in automotive components. Summary of the Invention

[0003] Based on the technical problems existing in the background technology, the present invention proposes an aluminum alloy containing La element and a preparation method thereof.

[0004] The present invention provides a method for preparing an aluminum alloy containing La, comprising the following steps:

[0005] S1. Add an aluminum ingot into an electric furnace and melt it at 740-750° C. to form aluminum liquid. Then, add an Al-Si master alloy, an Al-La master alloy, and a magnesium ingot to the aluminum liquid, fully melt the aluminum liquid, and then cool the temperature to 730-735° C. and keep the temperature for 10-20 minutes to obtain an aluminum alloy melt. The aluminum alloy melt has the following composition: Si 0.40-0.46%, Mg 0.55-0.65%, Fe≤0.35%, La 0.005-0.01%, and the balance is Al and unavoidable impurities.

[0006] S2, subjecting the aluminum alloy melt to ultrasonic treatment, then adding a grain refiner, keeping the temperature for 10 to 20 minutes, and casting to obtain an aluminum alloy ingot;

[0007] The preparation method of the grain refiner comprises: mixing Al powder, Ti powder and carbon powder, ball milling for 1.5 to 3 hours to obtain Al-Ti-C composite powder; then adding Mg powder and La powder to the Al-Ti-C composite powder, continuing ball milling for 0.5 to 1 hour, and pressing the obtained mixed powder into blocks.

[0008] S3, heating the aluminum alloy ingot to perform homogenization treatment, and then cooling;

[0009] S4. Hot-extrude the aluminum alloy ingot after homogenization treatment in S3, cool it, and then perform aging treatment to obtain the product.

[0010] In the method for preparing the grain refiner of the present invention, ball milling is performed under an inert gas protective atmosphere, such as an argon atmosphere.

[0011] In the present invention, Al-Ti-C composite powder is first prepared by mechanical ball milling, and then Mg powder and La powder are added to continue mechanical ball milling, so that Mg and La are coated on the surface of the Al-Ti-C composite powder as grain refiners. Adding them to the aluminum alloy melt can synergistically improve the mechanical strength of the aluminum alloy.

[0012] Preferably, in S2, the frequency of ultrasonic treatment is 20 to 30 kHz, and the time is 2 to 5 minutes.

[0013] Preferably, in S2, the amount of the grain refiner is 0.05-0.1% of the mass of the aluminum alloy melt.

[0014] Preferably, the rotation speed of the ball mill is 200-300 r / min, and the ball-to-material ratio is 5-10:1.

[0015] Preferably, in the Al-Ti-C composite powder, the mass percentage of Al is 70% to 80%, the mass percentage of Ti is 10% to 20%, and the mass percentage of C is 5% to 10%;

[0016] The mass of the Mg powder is 0.05% to 0.1% of the mass of the Al-Ti-C composite powder, and the mass of the La powder is 0.01% to 0.02% of the mass of the Al-Ti-C composite powder.

[0017] Preferably, in S3, the temperature of the homogenization treatment is 560-580° C., and the time is 6-8 hours.

[0018] Preferably, in S4, the temperature of the hot extrusion is 480-500°C;

[0019] The aging treatment is performed at a temperature of 170 to 180° C. and for a time of 7 to 9 hours.

[0020] The present invention also provides an aluminum alloy containing La element, which is prepared by the preparation method.

[0021] The beneficial effects of the present invention are as follows:

[0022] The present invention is based on the Al-Mg-Si series 6063 aluminum alloy composition. A small amount of rare earth La is introduced during the raw material smelting process, which can play a role in grain refinement and does not affect the main strengthening phase Mg2Si phase in the alloy, thereby improving the mechanical strength of the aluminum alloy; the formed aluminum alloy melt is subjected to ultrasonic treatment to remove impurities in the melt and purify the melt. At the same time, the ultrasonic treatment can also play a role in grain refinement; a grain refiner formed by Mg and La coated on the surface of the Al-Ti-C composite powder is added to the purified aluminum alloy melt, wherein Al-Ti-C can form TiAl3 and TiC nuclei to refine the grains, La can promote nucleation formation, Mg can improve the wettability of nucleation, and ultrasonic purification can avoid the influence of impurities in the melt on the easily reactive metals Mg and La, better play the promoting effect of Mg and La on the grain refiner, thereby further improving the mechanical strength of the aluminum alloy. In summary, the preparation method of the aluminum alloy of the present invention can effectively improve the mechanical strength of the aluminum alloy and improve the performance of the aluminum alloy. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is described in detail below through specific embodiments.

[0024] Example 1

[0025] Preparation of grain refiner:

[0026] Al powder, Ti powder and carbon powder were mixed and ball milled for 2 h under argon atmosphere at a rotation speed of 200 r / min and a ball-to-material ratio of 10:1 to obtain Al-Ti-C composite powder, in which the mass percentage of Al, the mass percentage of Ti and the mass percentage of C were 85%, 10% and 5% respectively.

[0027] Mg powder and La powder were added to the above-mentioned Al-Ti-C composite powder, wherein the mass of Mg powder was 0.08% of the mass of the Al-Ti-C composite powder, and the mass of La powder was 0.02% of the mass of the Al-Ti-C composite powder. Ball milling was continued for 0.5 h under an argon atmosphere at a rotation speed of 200 r / min and a ball-to-material ratio of 10:1. The obtained mixed powder was pressed into blocks under a pressure of 20 MPa.

[0028] Preparation of aluminum alloy containing La element:

[0029] S1. An aluminum ingot is placed in an electric furnace and melted at 740° C. to form aluminum liquid. An Al-Si20 master alloy, an Al-La10 master alloy, and a magnesium ingot are then added to the aluminum liquid, fully melted, and then cooled to 730° C. and kept warm for 15 minutes to obtain an aluminum alloy melt. The aluminum alloy melt has the following composition: Si 0.42%, Mg 0.60%, Fe 0.127%, La 0.006%, and the balance being Al and unavoidable impurities.

[0030] S2. Ultrasonic treatment of the aluminum alloy melt at a frequency of 20 kHz for 3 minutes, then adding the grain refiner prepared above, keeping the temperature for 10 minutes, and casting to obtain an aluminum alloy ingot, wherein the amount of the grain refiner is 0.08% by mass of the aluminum alloy melt;

[0031] S3, homogenizing the aluminum alloy ingot at 575° C. for 8 h, and then cooling with water;

[0032] S4. The aluminum alloy ingot after homogenization treatment in S3 is hot extruded at 480-500° C., then water-cooled, and then aged at 175° C. for 8 hours to obtain the obtained product.

[0033] Example 2

[0034] Preparation of grain refiner:

[0035] Al powder, Ti powder and carbon powder were mixed and ball milled for 1.5 h under argon atmosphere at a rotation speed of 300 r / min and a ball-to-material ratio of 5:1 to obtain Al-Ti-C composite powder, in which the mass percentage of Al, the mass percentage of Ti and the mass percentage of C were 70%, 20% and 10% respectively.

[0036] Mg powder and La powder were added to the above-mentioned Al-Ti-C composite powder, wherein the mass of Mg powder was 0.05% of the mass of the Al-Ti-C composite powder, and the mass of La powder was 0.01% of the mass of the Al-Ti-C composite powder. Ball milling was continued for 0.5 h under an argon atmosphere at a rotation speed of 300 r / min and a ball-to-material ratio of 5:1. The obtained mixed powder was pressed into blocks under a pressure of 20 MPa.

[0037] Preparation of aluminum alloy containing La element:

[0038] S1. Add an aluminum ingot into an electric furnace and melt it at 745° C. to form aluminum liquid. Then, add an Al-Si20 master alloy, an Al-La10 master alloy, and a magnesium ingot to the aluminum liquid, fully melt the aluminum liquid, and then cool the temperature to 735° C. and hold the temperature for 10 minutes to obtain an aluminum alloy melt. The aluminum alloy melt has the following composition: Si 0.40%, Mg 0.56%, Fe 0.148%, La 0.008%, and the balance is Al and unavoidable impurities.

[0039] S2. Ultrasonic treatment of the aluminum alloy melt at a frequency of 20 kHz for 2 minutes, then adding the grain refiner prepared above, keeping the temperature for 10 minutes, and casting to obtain an aluminum alloy ingot, wherein the amount of the grain refiner is 0.05% by mass of the aluminum alloy melt;

[0040] S3, homogenizing the aluminum alloy ingot at 560° C. for 8 h, and then cooling with water;

[0041] S4. The aluminum alloy ingot after homogenization treatment in S3 is hot extruded at 480-500° C., then water-cooled, and then aged at 170° C. for 7 hours to obtain the obtained product.

[0042] Example 3

[0043] Preparation of grain refiner:

[0044] Al powder, Ti powder and carbon powder were mixed and ball milled for 3 h under argon atmosphere at a rotation speed of 300 r / min and a ball-to-material ratio of 10:1 to obtain Al-Ti-C composite powder, in which the mass percentage of Al, the mass percentage of Ti and the mass percentage of C were 80%, 10% and 10% respectively.

[0045] Mg powder and La powder were added to the above-mentioned Al-Ti-C composite powder, wherein the mass of Mg powder was 0.1% of the mass of the Al-Ti-C composite powder, and the mass of La powder was 0.02% of the mass of the Al-Ti-C composite powder. Ball milling was continued for 1 hour under an argon atmosphere at a rotation speed of 300 r / min and a ball-to-material ratio of 10:1. The obtained mixed powder was pressed into blocks under a pressure of 30 MPa to obtain the product.

[0046] Preparation of aluminum alloy containing La element:

[0047] S1. Add an aluminum ingot into an electric furnace and melt it at 750° C. to form aluminum liquid. Then, add an Al-Si20 master alloy, an Al-La10 master alloy, and a magnesium ingot to the aluminum liquid, fully melt the aluminum liquid, and then cool the temperature to 735° C. and hold the temperature for 20 minutes to obtain an aluminum alloy melt. The aluminum alloy melt has the following composition: Si 0.44%, Mg 0.62%, Fe 0.133%, La 0.008%, and the balance is Al and unavoidable impurities.

[0048] S2. Ultrasonic treatment of the aluminum alloy melt at a frequency of 30 kHz for 5 minutes, then adding the grain refiner prepared above, keeping the temperature for 20 minutes, and casting to obtain an aluminum alloy ingot, wherein the amount of the grain refiner is 0.1% by mass of the aluminum alloy melt;

[0049] S3, homogenizing the aluminum alloy ingot at 580° C. for 8 h, and then cooling with water;

[0050] S4. The aluminum alloy ingot after homogenization treatment in S3 is hot extruded at 480-500° C., then water-cooled, and then aged at 180° C. for 9 hours to obtain the obtained product.

[0051] Comparative Example 1

[0052] The only difference between Comparative Example 1 and Example 1 is that the grain refiner is different. The preparation method of the grain refiner of Comparative Example 1 is as follows:

[0053] After mixing Al powder, Ti powder and carbon powder, ball milling was carried out for 2 h under argon atmosphere at a rotation speed of 200 r / min and a ball-to-material ratio of 10:1 to obtain Al-Ti-C composite powder. The obtained Al-Ti-C composite powder was pressed into blocks under a pressure of 20 MPa.

[0054] Comparative Example 2

[0055] The only difference between Comparative Example 2 and Example 1 is that ultrasonic treatment is not performed during the preparation of the aluminum alloy, as follows:

[0056] S1. An aluminum ingot is placed in an electric furnace and melted at 740° C. to form aluminum liquid. An Al-Si20 master alloy, an Al-La10 master alloy, and a magnesium ingot are then added to the aluminum liquid, fully melted, and then cooled to 730° C. and kept warm for 15 minutes to obtain an aluminum alloy melt. The aluminum alloy melt has the following composition: Si 0.42%, Mg 0.60%, Fe 0.127%, La 0.006%, and the balance being Al and unavoidable impurities.

[0057] S2. Adding a grain refiner to the aluminum alloy melt, keeping the temperature for 10 minutes, and casting to obtain an aluminum alloy ingot, wherein the amount of the grain refiner is 0.08% by mass of the aluminum alloy melt;

[0058] S3, homogenizing the aluminum alloy ingot at 575° C. for 8 h, and then cooling with water;

[0059] S4. The aluminum alloy ingot after homogenization treatment in S3 is hot extruded at 480-500° C., then water-cooled, and then aged at 175° C. for 8 hours to obtain the obtained product.

[0060] The preparation method of the grain refiner is the same as that in Example 1.

[0061] Test example

[0062] The aluminum alloys prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were tested, and the test results are shown in Table 1:

[0063] Table 1

[0064]

[0065] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for preparing an aluminum alloy containing La, characterized in that: The following steps are involved: S1. Add an aluminum ingot into an electric furnace and melt it at 740-750° C. to form aluminum liquid. Then, add an Al-Si master alloy, an Al-La master alloy, and a magnesium ingot to the aluminum liquid, fully melt the aluminum liquid, and then cool the temperature to 730-735° C. and keep the temperature for 10-20 minutes to obtain an aluminum alloy melt. The aluminum alloy melt has the following composition: Si 0.40-0.46%, Mg 0.55-0.65%, Fe≤0.35%, La 0.005-0.01%, and the balance is Al and unavoidable impurities. S2, subjecting the aluminum alloy melt to ultrasonic treatment, then adding a grain refiner, keeping the temperature for 10 to 20 minutes, and casting to obtain an aluminum alloy ingot; The preparation method of the grain refiner comprises: mixing Al powder, Ti powder and carbon powder, ball milling for 1.5 to 3 hours to obtain Al-Ti-C composite powder; then adding Mg powder and La powder to the Al-Ti-C composite powder, continuing ball milling for 0.5 to 1 hour, and pressing the obtained mixed powder into blocks. S3, heating the aluminum alloy ingot to perform homogenization treatment, and then cooling; S4. Hot-extrude the aluminum alloy ingot after homogenization treatment in S3, cool it, and then perform aging treatment to obtain the product.

2. The method for preparing an aluminum alloy containing La according to claim 1, wherein: In S2, the frequency of ultrasonic treatment is 20 to 30 kHz, and the time is 2 to 5 minutes.

3. The method for preparing an aluminum alloy containing La according to claim 1, wherein: In S2, the amount of the grain refiner is 0.05-0.1% of the mass of the aluminum alloy melt.

4. The method for preparing an aluminum alloy containing La according to claim 1, wherein: The rotation speed of the ball mill is 200-300 r / min, and the ball-to-material ratio is 5-10:

1.

5. The method for preparing an aluminum alloy containing La according to claim 1, wherein: In the Al-Ti-C composite powder, the mass percentage of Al is 70% to 80%, the mass percentage of Ti is 10% to 20%, and the mass percentage of C is 5% to 10%; The mass of the Mg powder is 0.05% to 0.1% of the mass of the Al-Ti-C composite powder, and the mass of the La powder is 0.01% to 0.02% of the mass of the Al-Ti-C composite powder.

6. The method for preparing an aluminum alloy containing La according to claim 1, wherein: In S3, the homogenization treatment is performed at a temperature of 560 to 580° C. for 6 to 8 hours.

7. The method for preparing an aluminum alloy containing La according to claim 1, wherein: In S4, the temperature of the hot extrusion is 480-500°C; The aging treatment is performed at a temperature of 170 to 180° C. and for a time of 7 to 9 hours.

8. An aluminum alloy containing La, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 7.

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