High-toughness regenerated aluminum alloy and preparation method thereof

Abstract

The invention belongs to the field of aluminum alloy materials, and particularly relates to a high-toughness regenerated aluminum alloy and a preparation method thereof. The regenerated aluminum alloy is prepared from one or more of 4000-series aluminum waste, 6000-series aluminum waste, 1000-series aluminum waste, 3000-series aluminum waste, 5000-series aluminum waste and 8000-series aluminum waste, and contains an aluminum intermediate alloy and an alterant; a matrix of the regenerated aluminum alloy comprises one or more Fe-containing phases, and the components comprise one or more of Al, Si, Fe, Mn, Mo and V; and the size range of the Fe-containing phase is 1-20 [mu] m. According to the high-toughness regenerated aluminum alloy developed by the invention, the used raw materials are mainly aluminum wastes, the cost is low, meanwhile, the high-toughness regenerated aluminum alloy has better toughness and formability, and heat treatment is not needed. The yield strength of the heat-treatment-free regenerated aluminum alloy in a cast state is 120-150 MPa, the tensile strength of the heat-treatment-free regenerated aluminum alloy is 240-270 MPa, and the elongation is 9-15%.

Description

Technical Field

[0001] The invention belongs to the field of aluminum alloy materials, and specifically relates to a high-strength and toughness recycled aluminum alloy and a preparation method thereof. Background Art

[0002] With the increasing scarcity of global resources and energy shortage, energy conservation and environmental protection have become the consensus of aluminum processing companies around the world. Using recycled aluminum as raw material in the production process of aluminum alloy can greatly reduce the production cost of enterprises and generate huge energy-saving and environmental protection benefits. Since recycled aluminum comes from a variety of sources and contains complex elements, some harmful elements will form a hard and brittle second phase, which will seriously deteriorate the performance of the alloy and reduce the quality of castings. Therefore, it is particularly urgent to develop a utilization method that is suitable for it.

[0003] Heat treatment is an important processing method for aluminum alloys, which can change the structure and properties of aluminum alloy materials, with the aim of improving the strength, hardness, toughness and other properties of the materials. However, heat treatment not only causes deformation, but also reduces production efficiency, consumes a lot of energy and pollutes the environment. Therefore, the development of heat-treatment-free aluminum alloy materials has become a trend. Heat-treatment-free aluminum alloy refers to the technology of obtaining aluminum alloy products with good strength, plasticity, toughness and other properties without heat treatment after casting by adding other metal alloy components.

[0004] Chinese invention patent CN117488147A discloses a heat-treatment-free recycled aluminum alloy material and a preparation method thereof, which uses 1 series aluminum scrap, 3 series aluminum scrap, 6 series aluminum scrap and 7 series aluminum scrap as raw materials, and undergoes smelting, refining, metamorphism and die-casting to obtain an aluminum alloy whose strength and toughness can meet the use requirements.

[0005] Chinese invention patent CN117448634B discloses a renewable high-strength and toughness heat-treatment-free aluminum alloy and its preparation method and die-casting process. The purpose of the invention is to solve the problems of low strength and toughness of existing heat-treatment-free aluminum alloys and low allowable range of impurity elements such as Fe and Zn, and to provide a renewable high-strength and toughness heat-treatment-free aluminum alloy and its preparation method and die-casting process.

[0006] However, the aluminum alloy and processing method disclosed in the above patents, as well as some other prior arts, are severely limited in the selection of aluminum waste types, the allowable range of impurity elements such as Fe is low, and there are huge defects in strength, toughness and alloy structure. The present invention is of great significance in broadening the scope of use of recycled waste aluminum while improving the strength and toughness of heat-free recycled aluminum alloys and regulating alloy structure. Summary of the invention

[0007] In order to solve the above-mentioned technical problems, this application provides the following technical solutions:

[0008] The present invention provides a high-strength and toughness recycled aluminum alloy, wherein the raw materials of the high-strength and toughness recycled aluminum alloy are selected from 4000 series aluminum scrap, 6000 series aluminum scrap, mixed aluminum scrap, master alloy and modifier; the mixed aluminum scrap is selected from one or more of 1000 series aluminum scrap, 3000 series aluminum scrap, 5000 series aluminum scrap and 8000 series aluminum scrap, the master alloy is selected from Al-Mn, Al-Mo, Al-V, Al-Zr, Al-Sc and Al-Er master alloy, and the modifier is selected from Al-Sr and Al-Ca;

[0009] The matrix of the high-strength and toughness recycled aluminum alloy includes more than one Fe-containing phase, the components of the Fe-containing phase include Al, Si, Fe and metal element A, and the metal element A is selected from one or more of Mn, Mo and V; the size of the Fe-containing phase ranges from 1 to 20 μm, the morphology is fine mesh, short rod or polyhedron, and the crystal structure is selected from simple cubic or body-centered cubic;

[0010] The matrix of the high-strength and toughness recycled aluminum alloy comprises an Al-containing phase, wherein the Al-containing phase is selected from one or two of an AlZr phase, an AlV phase, an AlSc phase and an AlEr phase, and the Al-containing phase has a short rod-like morphology and a size of 3-10 μm.

[0011] Preferably, the components of the high-strength and toughness recycled aluminum alloy are as follows, by mass percentage: Si 4-10%, Mg 0.25-0.5%, Fe 0.2-0.8%, Mn 0.1-0.8%, Mo 0.1-0.6%, V 0.1-0.4%, Sc 0.01-0.1%, Zr 0.01-0.1%, Er 0.01-0.1%, Cr 0-0.1%, Sr 0.01-0.03%, Ca 0.001-0.05%, and the rest are Al and unavoidable impurity elements.

[0012] The present invention also provides a method for preparing the above-mentioned high-strength and toughness recycled aluminum alloy, comprising the following steps:

[0013] S1: Testing and determining the composition of the aluminum alloy scrap as the raw material, and preparing the raw material according to the aluminum alloy component formula; in terms of mass percentage, the aluminum alloy component formula is as follows: Si 4-10%, Mg 0.25-0.5%, Fe 0.2-0.8%, Mn 0.1-0.8%, Mo0.1-0.6%, V 0.1-0.4%, Sc 0.01-0.1%, Zr 0.01-0.1%, Er 0.01-0.1%, Cr 0-0.1%, Sr 0.01-0.03%, Ca 0.001-0.05%, and the rest are Al and unavoidable impurity elements;

[0014] S2: Under a protective atmosphere, heating the 6000 series aluminum scrap and the 4000 series aluminum scrap to 735-745° C. to obtain melt A;

[0015] S3: heating the melt A to 750-760° C. and adding 8000 series aluminum scrap to obtain a melt B;

[0016] S4: cooling the melt B to 735-745° C. and then adding 3000 series aluminum scrap, 5000 series aluminum scrap and 1000 series aluminum scrap to obtain a melt C;

[0017] S5: measuring the composition of the melt C, adding the intermediate alloy I according to the component formula in step S1, and keeping the temperature for 10-25 minutes to obtain a melt D;

[0018] S6: adding master alloy II to the melt D and keeping the temperature for 15-20 minutes to obtain melt E;

[0019] S7: adding a modifier to the melt E to modify the eutectic Si to obtain a melt F;

[0020] S8: Casting the melt F to obtain the high-strength and high-toughness recycled aluminum alloy.

[0021] Preferably, by weight, in the melt C, the proportion of 4000 series aluminum scrap is 70%-90%, the proportion of 1000 series aluminum scrap is 1%-15%, the proportion of 3000 series aluminum scrap is 2%-9%, the proportion of 5000 series aluminum scrap is 1%-8%, the proportion of 3000 series aluminum scrap is 2%-9%, the proportion of 8000 series aluminum scrap is 4%-15%, and the proportion of 6000 series aluminum scrap is 2%-15%.

[0022] Preferably, in step S2, heating is performed in a graphite crucible using induction heating in a medium frequency furnace.

[0023] Preferably, the intermediate alloy I is selected from Al-10Mn, Al-10Mo and Al-5V; the intermediate alloy II is selected from Al-2Sc, Al-5Zr and Al-10Er.

[0024] Preferably, the modifier is selected from Al-10Sr and Al-10Ca.

[0025] Preferably, the protective atmosphere is argon.

[0026] Preferably, in step S7, melt E is cooled to 710-720°C, a modifier is added, and then the temperature is increased to 720-730°C, degassing, standing and slagging are performed to obtain melt F.

[0027] Furthermore, the static method is to introduce the melt into a static furnace and let it stand for 8-10 minutes.

[0028] Specifically, the preparation method comprises the following steps:

[0029] (1) Test the scrap composition and prepare the alloy according to the target alloy composition;

[0030] (2) In an argon protective atmosphere, 6000 series and 4000 series aluminum scraps are placed in a graphite crucible and placed in a medium frequency furnace for induction heating to form a melt;

[0031] (3) The melt is heated to 750-760°C and 8000 series alloy scrap is added;

[0032] (4) Cooling to 735-745°C, adding 3000 series, 5000 series and 1000 series aluminum scraps;

[0033] (5) Testing the melt composition and adding Al-10Mn, Al-10Mo, and Al-5V master alloys into the alloy melt, stirring the melt fully after it is completely melted, and keeping it warm for 10 to 25 minutes;

[0034] (6) Continue to add Al-2Sc, Al-5Zr, and Al-10Er master alloys and keep warm for 15 to 20 minutes;

[0035] (7) In an argon protective atmosphere, the melt was heated to 710-720°C, and Al-10Sr and Al-10Ca were added to modify the eutectic Si for 15 min;

[0036] (8) The alloy melt is heated to 720-730°C, degassed, and then introduced into a static furnace for 8-10 minutes before slagging;

[0037] (9) The melt is poured into a mold and allowed to stand until it is completely solidified to obtain an alloy.

[0038] Preferably, in step S7, the melt E is cooled to 720-730° C., and after impurity treatment, cooled to 700-720° C., a modifier is added, and impurity treatment is performed again to obtain a melt F; the impurity treatment method is to remove the slag on the surface of the aluminum liquid after degassing.

[0039] Furthermore, the degassing time is 10 minutes.

[0040] Preferably, in step S8, the casting temperature is 680-700° C., and a water-cooled copper mold is used for casting.

[0041] Specifically, the preparation method comprises the following steps:

[0042] S1. Test the composition of all aluminum alloy scraps to determine the types and contents of elements contained in each grade of scrap;

[0043] S2. Mixing the ingredients according to the tested alloy composition and the recycled aluminum alloy composition of claim 2;

[0044] S3, smelting process: (1) heating 6000 series and 4000 series aluminum scraps into a melt under a protective atmosphere; (2) raising the temperature to 750-760°C and adding 8000 series alloy scraps; (3) cooling the temperature to 735-745°C and adding 3000 series, 5000 series and 1000 series alloy scraps; (4) testing the melt composition and adding Al-10Mn, Al-10Mo, Al-5V master alloys, and keeping the temperature for 10-25 minutes; (5) continuing to add Al-2Sc, Al-5Zr, Al-10Er master alloys, and keeping the temperature for 15-20 minutes;

[0045] S4, degassing process: when the temperature of the aluminum liquid drops to 720-730℃, degas for 10 minutes. After degassing, remove the scum on the surface of the aluminum liquid and keep it warm for a period of time; when the temperature of the aluminum liquid drops to 700-720℃, add Al-Sr and Al-Ca master alloys, degas again for 10 minutes, and remove the scum on the surface of the aluminum liquid again;

[0046] S5. Casting: After the molten metal is refined to be qualified, the pouring temperature of the molten aluminum is maintained at 680-700°C, and a water-cooled copper mold is used to obtain the alloy.

[0047] The technical solution of the present invention has the following advantages over the prior art:

[0048] The high-strength and toughness recycled aluminum alloy of the present invention uses 1000 series aluminum scrap, 3000 series aluminum scrap, 4000 series aluminum scrap, 5000 series aluminum scrap, 6000 series aluminum scrap, 8000 series aluminum scrap, Al-Mo, Al-V, Al-Sc, Al-Zr, Al-Er intermediate alloys and Al-Sr and Al-Ca modifiers, controls the alloy composition and proportion, so that one or more strengthening phases such as Fe phase, AlV, AlSc, AlZr, AlEr, etc. are formed in the matrix of the aluminum alloy, so that the aluminum alloy has good strength, toughness and formability, and no heat treatment is required. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a schematic diagram of the alloy structure of Example 1 of the present invention;

[0050] Figure 2 is a schematic diagram of the alloy structure of Example 2 of the present invention;

[0051] Figure 3 is a schematic diagram of the alloy structure of Example 3 of the present invention;

[0052] Figure 4 is a schematic diagram of the alloy structure of Example 4 of the present invention;

[0053] Figure 5 Schematic diagram of the alloy structure of Example 5 of the present invention. DETAILED DESCRIPTION

[0054] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0055] Example 1

[0056] The present embodiment discloses a method for preparing a high-strength and tough recycled aluminum alloy, which has good strength, toughness and formability and does not require heat treatment. The components of the aluminum alloy and the weight percentages of the components are: Si 4%, Mg 0.25%, Fe 0.2%, Mn 0.1%, Mo 0.1%, V 0.1%, Cr 0.01%, Sr 0.01%, Ca 0.01%, and the rest are Al and unavoidable impurity elements.

[0057] The method for preparing the cast aluminum alloy based on the above composition in this embodiment comprises the following steps:

[0058] (1) Testing the composition of the waste; (2) In an argon protective atmosphere, placing 6000 series and 4000 series aluminum waste in a graphite crucible and placing it in a medium frequency furnace for induction heating to 740°C; (3) Heating the melt to 750-760°C and adding 8000 series alloy waste; (4) Cooling the melt to 735-745°C and adding 3000 series, 5000 series and 1000 series alloy waste; (5) Testing the composition of the melt and adding Al-10Mn, Al-10Mo and Al-5V master alloys to the alloy melt, stirring the melt until it is completely melted, and keeping the temperature for 10-20 minutes. 25min; (6) Continue to add Al-2Sc, Al-5Zr, and Al-10Er intermediate alloys and keep warm for 15-20min; (7) Under argon protective atmosphere, heat the melt to 710-720℃, add Al-10Sr and Al-10Ca to modify the eutectic Si, and the modification time is 15min; (8) Heat the alloy melt to 720-730℃, degas, and then introduce it into a standing furnace. After standing for 8-10min, remove the slag; (9) Pour the melt into a mold, let it stand until it is completely solidified, and obtain an ingot.

[0059] The metallographic structure of the alloy ingot obtained in this embodiment is as follows Figure 1As shown in FIG. 1 , through organizational observation, it is found that there are a large number of fine mesh and short rod-shaped Fe phases in the alloy matrix of this embodiment, and its crystal structure includes a simple cubic structure and a body-centered cubic structure; the size range of the fine mesh Fe phase is about 20 μm, and the size range of the short rod-shaped Fe phase is about 10 μm; the number density of the Fe phase is about 10 10 / m 3 ; In the figure, we can see a small amount of short rod-shaped AlV, AlZr, AlSc and AlE phases, with a size range of about 15μm and a number density of 10 13 / m 3 .

[0060] The secondary aluminum alloy prepared in this embodiment has a yield strength of 120 MPa, a tensile strength of 240 MPa, and an elongation of 9% in the cast state.

[0061] Example 2

[0062] The present embodiment discloses a method for preparing a high-strength and tough recycled aluminum alloy, which has good strength, toughness and formability and does not require heat treatment. The components and weight percentages of the aluminum alloy are: Si 6%, Mg 0.5%, Fe 0.4%, Mn 0.3%, Mo 0.3%, V 0.2%, Cr 0.03%, Sr 0.02%, Ca 0.03%, and the rest are Al and unavoidable impurity elements.

[0063] The preparation method of the above alloy is basically the same as that of Example 1. The metallographic structure of the alloy ingot is as follows: Figure 2 As shown. Through organizational observation, it is found that there are still a large number of fine mesh and short rod-shaped Fe phases in the alloy matrix of this embodiment, and its crystal structure includes simple cubic structure and body-centered cubic structure; the size range of Fe phase is about 20μm; the number density of Fe phase is about 10 13 / m 3 ; In the figure, we can see a small amount of short rod-shaped AlV, AlZr, AlSc and AlE phases, with a size range of about 10μm and a number density of 10 13 / m 3 .

[0064] The secondary aluminum alloy prepared in this embodiment has a yield strength of 128 MPa, a tensile strength of 250 MPa, and an elongation of 11% in the cast state.

[0065] Example 3

[0066] The present embodiment discloses a method for preparing a high-strength and tough recycled aluminum alloy, which has good strength, toughness and formability and does not require heat treatment. The components and weight percentages of the alloy are: Si 8%, Mg 0.3%, Fe 0.6%, Mn 0.5%, Mo 0.4%, V 0.3%, Cr 0.06%, Sr 0.02%, Ca 0.04%, and the rest are Al and unavoidable impurity elements.

[0067] The preparation method of the above alloy is basically the same as that of Example 1. The metallographic structure of the alloy ingot is as follows: Figure 3 As shown. Through organizational observation, it is found that there are fine mesh, short rod and polyhedral Fe phases in the alloy matrix of this embodiment, and its crystal structure includes simple cubic structure and body-centered cubic structure; the size range of Fe phase is about 10μm; the number density of Fe phase is about 10 14 / m 3 At the same time, some short rod-shaped AlV, AlZr, AlSc and AlE phases can be seen in the figure, with a size range of about 10 μm and a number density of 10 14 / m 3 .

[0068] The regenerated Al-Si series heat-treatment-free cast aluminum alloy prepared in this embodiment has a yield strength of 140 MPa, a tensile strength of 260 MPa, and an elongation of 13% in the cast state.

[0069] Example 4

[0070] The present embodiment discloses a method for preparing a high-strength and tough recycled aluminum alloy, which has good strength, toughness and formability and does not require heat treatment. The components and weight percentages of the alloy are: Si 9%, Mg 0.35%, Fe 0.7%, Mn 0.7%, Mo 0.5%, V 0.35%, Cr 0.08%, Sr 0.03%, Ca 0.05%, and the rest are Al and unavoidable impurity elements.

[0071] The preparation method of the above alloy is basically the same as that of Example 1. The metallographic structure of the alloy ingot is as follows: Figure 4 As shown. Through organizational observation, it is found that there are fine mesh, short rod and polyhedral Fe phases in the alloy matrix of this embodiment, and its crystal structure includes simple cubic structure and body-centered cubic structure; the size range of Fe phase is about 6μm; the number density of Fe phase is about 10 14 / m 3 At the same time, it can be seen in the figure that there are some short rod-shaped AlV, AlZr, AlSc and AlE phases at the grain boundaries, with a size range of about 6μm and a number density of 10 14 / m 3 .

[0072] The secondary aluminum alloy prepared in this embodiment has a yield strength of 145 MPa, a tensile strength of 270 MPa, and an elongation of 14% in the cast state.

[0073] Example 5

[0074] The present embodiment discloses a method for preparing a high-strength and tough recycled aluminum alloy, which has good strength, toughness and formability and does not require heat treatment. The components and weight percentages of the alloy are: Si 10%, Mg 0.38%, Fe 0.8%, Mn 0.8%, Mo 0.6%, V 0.4%, Cr 0.1%, Sr 0.03%, Ca 0.05%, and the rest are Al and unavoidable impurity elements.

[0075] The preparation method of the above alloy is basically the same as that of Example 1. The metallographic structure of the alloy ingot is as follows: Figure 5 As shown. Through microstructural observation, it is found that there are fine mesh, short rod and polyhedral Fe phases in the alloy matrix of this embodiment, and its crystal structure includes simple cubic structure and body-centered cubic structure; the size range of Fe phase is about 3μm; the number density of Fe phase is about 10 12 / m 3 At the same time, it can be seen in the figure that there are some short rod-shaped AlZr, AlV, AlSc and AlEr phases at the grain boundaries, with a size range of about 4μm and a number density of 10 13 / m 3 .

[0076] The secondary aluminum alloy prepared in this embodiment has a yield strength of 150 MPa, a tensile strength of 270 MPa, and an elongation of 15% in the cast state.

[0077] Obviously, the above embodiments are merely examples for clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the protection scope of the invention.

Claims

1. A high-strength and tough recycled aluminum alloy, characterized in that: The raw materials of the high-strength and toughness recycled aluminum alloy are selected from 4000 series aluminum scrap, 6000 series aluminum scrap, mixed aluminum scrap, master alloy and modifier; the mixed aluminum scrap is selected from one or more of 1000 series aluminum scrap, 3000 series aluminum scrap, 5000 series aluminum scrap and 8000 series aluminum scrap, the master alloy is selected from Al-Mn, Al-Mo, Al-V, Al-Zr, Al-Sc and Al-Er master alloy, and the modifier is selected from Al-Sr and Al-Ca; The matrix of the high-strength and toughness recycled aluminum alloy includes more than one Fe-containing phase, the components of the Fe-containing phase include Al, Si, Fe and metal element A, and the metal element A is selected from one or more of Mn, Mo and V; the size of the Fe-containing phase ranges from 1 to 20 μm, the morphology is fine mesh, short rod or polyhedron, and the crystal structure is selected from simple cubic or body-centered cubic; The matrix of the high-strength and toughness recycled aluminum alloy comprises an Al-containing phase, wherein the Al-containing phase is selected from one or two of an AlZr phase, an AlV phase, an AlSc phase and an AlEr phase, and the Al-containing phase has a short rod-like morphology and a size of 3-10 μm.

2. The high-strength and tough recycled aluminum alloy according to claim 1, characterized in that: Calculated by mass percentage, the components of the high-strength and toughness recycled aluminum alloy are as follows: Si 4-10%, Mg 0.25-0.5%, Fe 0.2-0.8%, Mn 0.1-0.8%, Mo0.1-0.6%, V 0.1-0.4%, Sc 0.01-0.1%, Zr 0.01-0.1%, Er 0.01-0.1%, Cr 0-0.1%, Sr0.01-0.03%, Ca0.001-0.05%, and the rest are Al and unavoidable impurity elements.

3. A method for preparing the high-strength and tough recycled aluminum alloy according to claim 1 or 2, characterized in that: The steps include: S1: Testing and determining the composition of the aluminum alloy scrap as the raw material, and preparing the raw material according to the aluminum alloy component formula; in terms of mass percentage, the aluminum alloy component formula is as follows: Si 4-10%, Mg 0.25-0.5%, Fe 0.2-0.8%, Mn 0.1-0.8%, Mo0.1-0.6%, V 0.1-0.4%, Sc 0.01-0.1%, Zr 0.01-0.1%, Er 0.01-0.1%, Cr 0-0.1%, Sr 0.01-0.03%, Ca 0.001-0.05%, and the rest are Al and unavoidable impurity elements; S2: Under a protective atmosphere, heating the 6000 series aluminum scrap and the 4000 series aluminum scrap to 735-745° C. to obtain melt A; S3: heating the melt A to 750-760° C. and adding 8000 series aluminum scrap to obtain a melt B; S4: cooling the melt B to 735-745° C. and then adding 3000 series aluminum scrap, 5000 series aluminum scrap and 1000 series aluminum scrap to obtain a melt C; S5: measuring the composition of the melt C, adding the intermediate alloy I according to the component formula in step S1, and keeping the temperature for 10-25 minutes to obtain a melt D; S6: adding master alloy II to the melt D and keeping the temperature for 15-20 minutes to obtain melt E; S7: adding a modifier to the melt E to modify the eutectic Si to obtain a melt F; S8: Casting the melt F to obtain the high-strength and high-toughness recycled aluminum alloy.

4. The preparation method according to claim 3, characterized in that: In terms of weight percentage, in the melt C, the proportion of 4000 series aluminum scrap is 70%-90%, the proportion of 1000 series aluminum scrap is 1%-15%, the proportion of 3000 series aluminum scrap is 2%-9%, the proportion of 5000 series aluminum scrap is 1%-8%, the proportion of 3000 series aluminum scrap is 2%-9%, the proportion of 8000 series aluminum scrap is 4%-15%, and the proportion of 6000 series aluminum scrap is 2%-15%.

5. The preparation method according to claim 3, characterized in that: The intermediate alloy I is selected from Al-10Mn, Al-10Mo and Al-5V; the intermediate alloy II is selected from Al-2Sc, Al-5Zr and Al-10Er.

6. The preparation method according to claim 3, characterized in that: The modifier is selected from Al-10Sr and Al-10Ca.

7. The preparation method according to claim 3, characterized in that: In step S7, melt E is cooled to 710-720° C., a modifier is added, and then the temperature is increased to 720-730° C., degassing, standing and slagging are performed to obtain melt F.

8. The preparation method according to claim 7, characterized in that: The static method is to introduce the melt into a static furnace and let it stand for 8-10 minutes.

9. The preparation method according to claim 3, characterized in that: In the step S7, the melt E is cooled to 720-730°C, and after impurity treatment, cooled to 700-720°C, a modifier is added, and impurity treatment is performed again to obtain a melt F; the impurity treatment method is to remove the slag on the surface of the aluminum liquid after degassing.

10. The preparation method according to claim 3, characterized in that: In step S8, the casting temperature is 680-700° C., and a water-cooled copper mold is used for casting.

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