Composite alterant for cast aluminum alloy and preparation method of composite alterant

Abstract

The invention belongs to the field of aluminum alloy materials, and particularly relates to a cast aluminum alloy composite modifier and a preparation method thereof. The composite modifier comprises two or more of sub-micron TiC, NiC, Al3B, Al3Ti, TiB2, Al4C3, (TiNd) B2, (TiZr) B2 and (TiHf) B2 nucleating agents, and further comprises two or more of La, Ce, Y, Sb, Te, Sn, Be, Ca, Sr and Bi modification elements. Wherein the size of the submicron phase ranges from 20 nm to 300 nm; the preparation method of the composite alterant comprises the following steps: smelting, casting, rolling and drawing pure Al and a required intermediate alloy to obtain an alterant wire. The composite modifier provided by the invention is uniform in component and high in modification effect stability, can realize simultaneous modification of eutectic Si and Fe-containing compounds, and effectively improves the strength, toughness, corrosion resistance and fatigue resistance of the alloy.

Description

Technical Field

[0001] The invention belongs to the field of aluminum alloy materials, and in particular relates to a composite modifier for casting aluminum alloy and a preparation method thereof. Background Art

[0002] High-quality recycling of aluminum alloy scrap has huge economic and environmental benefits. Relevant statistics show that compared with electrolytic aluminum, every ton of recycled aluminum can save about 13,500 kWh of electricity and reduce 76 m 3 The waste discharge can save 10.5 tons of water and 8 tons of aluminum ore, and reduce 350 kg of CO2 emissions. However, due to the excessive content of impurity elements and the difficulty in removing them, a large number of cast Al-Si alloy parts waste can only be downgraded after recycling, resulting in a waste of resources.

[0003] Fe is a common impurity element in aluminum alloys. Excessive Fe content often leads to the appearance of coarse Fe-containing compounds, which seriously reduces the mechanical properties of the alloy. Previous studies have shown that converting Fe impurity elements into primary Fe-containing compounds and separating them by utilizing the characteristics of their liquid phase precipitation can effectively reduce the Fe content in the alloy. However, due to technical limitations, the Fe content in the alloy is difficult to be completely removed. The Fe element has a low solid solubility in the Al matrix and precipitates in the form of coarse Fe-containing compounds during the solidification of the alloy, which has a great impact on the strength, toughness, fatigue resistance and corrosion resistance of the alloy. Therefore, it is of great significance to refine the Fe-containing compounds in Al-Si alloys by specific means, which is of great significance for the regulation of the microstructure and mechanical properties of the regenerated Al-Si alloy and the realization of its high-quality regeneration.

[0004] Chinese invention patent CN109487107B discloses a composite modifier and a modification method for cast aluminum alloy with both iron-rich phase modification. The modifier mainly contains Mn, Sr, La and Ce elements, wherein Mn has a small modification effect on the Fe-containing phase, and when the amount of Mn added is too large, it is easy to produce coarse Fe-containing compound particles, which reduces the mechanical properties of the alloy. Excessive addition of Sr elements easily leads to alloy air absorption and pores. Chinese invention patent CN118460887 A discloses a refinement modifier and a preparation method thereof, wherein the refinement modifier mainly promotes the nucleation of Fe-containing compounds by forming TiB2, TiBC, TiC, and VB2 nucleation particles, and has a modification effect on Fe-containing compounds to a certain extent, but the nucleation particles cannot inhibit the growth of Fe-containing compounds, the modification effect is limited, and the size refinement effect is limited. Therefore, how to simultaneously improve the nucleation of Fe-containing compounds and hinder the growth of Fe-containing compounds, thereby refining the size of Fe-containing compounds, is of great significance for improving the mechanical properties of alloys. Summary of the invention

[0005] The object of the present invention is to provide a composite modifier for casting aluminum alloy and a preparation method thereof, so as to solve one or more technical problems existing in the prior art.

[0006] In order to solve the above-mentioned technical problems, this application provides the following technical solutions: The present invention provides a composite modifier for cast aluminum alloys, which comprises a submicron nucleating agent; the submicron nucleating agent is selected from two or more of TiC, NiC, Al3B, Al3Ti, TiB2, Al4C3, (TiNd)B2, (TiZr)B2, and (TiHf)B2; The composite modifier for casting aluminum alloy comprises, by weight fraction, Ti 2%-5%, B 0.1%-3%, C 0.1%-1.0%, Ni 0.2-1.0%, Nd 0.2-1.0%, Hf 0-0.3%, Zr 0-0.1%, Sc0-0.1% and a modifier; the modifier is selected from two or more of La, Ce, Y, Sb, Te, Sn, Be, Ca, Sr and Bi elements, and can be stably adsorbed on the growth crystal plane containing Fe phase and eutectic Si.

[0007] It can simultaneously achieve the modification of eutectic Si and Fe-containing compounds, refine the size of Fe-containing compounds, and effectively improve the strength, toughness, corrosion resistance and fatigue resistance of the alloy.

[0008] Preferably, the size of the submicron nucleating agent is in the range of 50-300 nm.

[0009] Preferably, the number density of the submicron nucleating agent is 10 15 -10 20 / m 3 .

[0010] The submicron nucleating agent is coherent or semi-coherent with the Fe-containing phase in common aluminum alloys; the submicron nucleating agent has a good adsorption effect on atoms such as Fe, Mn, Cr, and Si.

[0011] Preferably, the crystal structure of the submicron nucleating agent is selected from one or more of a simple cubic structure, a complex cubic structure, a tetragonal structure, a monoclinic structure and a close-packed hexagonal structure.

[0012] Preferably, the two-dimensional morphology of the submicron nucleating agent is selected from one or more of polygonal, short rod and spherical shapes.

[0013] Preferably, the total addition amount of the modifying elements in the composite modifying agent for casting aluminum alloy is 0.03-0.1%.

[0014] The present invention also provides a method for preparing the above-mentioned composite modifier for cast aluminum alloy, comprising the following steps: S11: preparing materials using aluminum and a master alloy; the master alloy is selected from a master alloy containing a submicron nucleating agent and a master alloy containing a modifying element; S12: Smelting and casting the raw materials after batching in step S11 to obtain a composite modifier ingot; S13: rolling the composite modifier ingot into a rod, drawing and annealing the rod to obtain the cast aluminum alloy composite modifier.

[0015] Preferably, in step S12, the smelting step is as follows: S21: melting aluminum and heating it to 750° C., adding a master alloy containing a submicron nucleating agent and heating it to 800-1000° C. to melt the mixture, thereby obtaining a melt; S22: Cooling the melt to 750° C., adding a master alloy containing a modification element to melt, and degassing.

[0016] Furthermore, a protective atmosphere is used during both smelting and degassing; the protective atmosphere is selected from argon or nitrogen.

[0017] Preferably, in step S12, the cooling rate of the melt during casting is 200-500K / s.

[0018] Specifically, the preparation method of the composite modifier comprises the following steps: (1) The aluminum alloy composite modifier with the above components is prepared and smelted. The smelting process is as follows: Introduce high-purity argon or nitrogen for protection; First, pure aluminum is melted and heated to 750°C; Then, the intermediate alloy containing the nucleating agent is added, and the melt temperature is continued to be raised to 800° C., so that the intermediate alloy containing the nucleating agent is fully melted; The melt is then cooled to 750°C, a master alloy containing a modifying element is added, and then degassing is performed and casting is performed to obtain an ingot, with a melt cooling rate of 200-500K / s; (2) The modifier ingot in step (1) is rolled to obtain a rod, and then drawn and annealed to finally obtain a composite modifier.

[0019] The technical solution of the present invention has the following advantages over the prior art: The composite modifier provided by the present invention has uniform composition and high stability of the modification effect, and can realize simultaneous modification of eutectic Si and Fe-containing compounds, thereby effectively improving the strength, toughness, corrosion resistance and fatigue resistance of the alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The alloy structure is obtained for Example 1; Figure 2 The alloy structure is obtained for Example 2; Figure 3 The alloy structure is obtained for Example 3; Figure 4 The alloy structure of Example 4 is obtained. DETAILED DESCRIPTION

[0021] 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. Example 1

[0022] The present embodiment discloses a composite modifier for casting aluminum alloy and a method for preparing the modifier, which has uniform composition and high stability of the modification effect, can simultaneously modify eutectic Si and Fe-containing compounds, and effectively improves the strength, toughness and fatigue resistance of the alloy. The components and weight percentages of the composite modifier for aluminum alloy are: Ti 2%, B 0.1%, C 0.1%, Hf 0.1%, Ni 0.2%, Nd 0.2%, La 0.1%, Ce 0.1%, and the rest is Al.

[0023] The preparation method of the composite modifier for cast aluminum alloy based on the above components in this embodiment comprises the following steps: (1) The aluminum alloy composite modifier with the above components is prepared and smelted. The smelting process is as follows: Introduce high-purity argon or nitrogen for protection; First, pure aluminum is melted and heated to 750°C; Then add Al-10Ti, Al-3B, Al-5Ti-C master alloys, and continue to heat the melt to 800°C to fully melt the master alloy containing the nucleating agent; Then the melt is cooled to 750°C, Al-10La, Al-10Ce, and Al-10Hf master alloys are added, and after the master alloys are fully melted, they are degassed with high-purity argon gas, and then cast to obtain an ingot, with a melt cooling rate of 200K / s; (2) The modifier ingot in step (1) is rolled to obtain a rod, and then drawn and annealed to finally obtain a composite modifier.

[0024] The alloy structure obtained in this embodiment is as follows Figure 1 As shown. Through organizational observation, it was found that the composite metamorphism contained TiC, Al3B, Al3Ti, TiB2, and Al4C3 nucleating agents, and their two-dimensional morphologies included polygons, short rods, and spheres, with a number density of 10 17 / m3 The crystal structure includes simple cubic structure, complex cubic structure, tetragonal structure, monoclinic structure or close-packed hexagonal structure, and the submicron nucleating agent is coherent or semi-coherent with the Fe-containing phase in common aluminum alloys, and has a good adsorption effect on atoms such as Fe, Mn, Cr, and Si. Example 2

[0025] The present embodiment discloses a composite modifier for casting aluminum alloy and a method for preparing the modifier, which has uniform composition and high stability of the modification effect, can simultaneously modify eutectic Si and Fe-containing compounds, and effectively improves the strength, toughness and fatigue resistance of the alloy. The components and weight percentages of the composite modifier for aluminum alloy are: Ti 3%, B 1%, C 0.5%, Ni 0.6%, Nd 0.6%, Hf 0.2%, Y 0.1%, Sb 0.1%, Sn 0.1%, and the rest is Al.

[0026] The preparation method of the composite modifier for cast aluminum alloy based on the above components in this embodiment comprises the following steps: (1) The aluminum alloy composite modifier with the above components is prepared and smelted. The smelting process is as follows: Introduce high-purity argon or nitrogen for protection; First, pure aluminum is melted and heated to 750°C; Then add Al-10Ti, Al-3B, Al-5Ti-C, and Al-10Ni master alloys, and continue to heat the melt to 900°C to fully melt the master alloy containing the nucleating agent; Then the melt is cooled to 750°C, and Al-10Y, Al-10Sr, Al-10Hf, and Al-10Sr master alloys are added. After the master alloys are fully melted, they are degassed with high-purity argon gas, and then cast to obtain an ingot, and the melt cooling rate is 300K / s; (2) The modifier ingot in step (1) is rolled to obtain a rod, which is then drawn and annealed to obtain a composite modifier.

[0027] The alloy structure obtained in this embodiment is as follows Figure 2 As shown. Through organizational observation, it is found that the nucleating agents in the composite modifier mainly include TiC, NiC, Al3B, Al3Ti, TiB2, Al4C3, (TiNd) B2 nucleating agents, and their two-dimensional shapes include polygons, short rods or spheres, with a number density of 10 18 / m 3 The crystal structure includes simple cubic structure, complex cubic structure, tetragonal structure, monoclinic structure or close-packed hexagonal structure, and the submicron nucleating agent is coherent or semi-coherent with the Fe-containing phase in common aluminum alloys, and has a good adsorption effect on atoms such as Fe, Mn, Cr, and Si. Example 3

[0028] The present embodiment discloses a composite modifier for casting aluminum alloy and a method for preparing the modifier, which has uniform composition and high stability of the modification effect, can simultaneously modify eutectic Si and Fe-containing compounds, and effectively improves the strength, toughness and fatigue resistance of the alloy. The components and weight percentages of the composite modifier for aluminum alloy are: Ti 4%, B 2%, C 1%, Ni 0.8%, Nd 0.8%, Zr 0.1%, Sc0.1%, Hf 0.3%, Sn 0.1%, Be 0.1%, Ca 0.1%, Sr0.1%, and the rest is Al.

[0029] The preparation method of the composite modifier for cast aluminum alloy based on the above components in this embodiment comprises the following steps: (1) The aluminum alloy composite modifier with the above components is prepared and smelted. The smelting process is as follows: Introduce high-purity argon or nitrogen for protection; First, pure aluminum is melted and heated to 750°C; Then add Al-10Ti, Al-3B, Al-5Ti-C, Al-10Ni, Al-5 Nd, and Al-5Zr master alloys, and continue to heat the melt to 950°C to fully melt the master alloy containing the nucleating agent; Then the melt is cooled to 750°C, and Al-50Sn, Al-3Be, Al-10Ca, and Al-10Sr master alloys are added. After the master alloys are fully melted, they are degassed with high-purity argon gas, and then cast to obtain an ingot, with a melt cooling rate of 400K / s. (2) The modifier ingot in step (1) is rolled to obtain a rod, which is then drawn and annealed to obtain a composite modifier.

[0030] The alloy structure obtained in this embodiment is as follows Figure 3 As shown. Through organizational observation, it is found that the nucleating agents of TiC, NiC, Al3B, Al3Ti, TiB2, Al4C3, (TiNd)B2, (TiZr)B2, (TiSc)B2, and (TiHf)B2 in the composite modifier have two-dimensional morphologies including short rods and spheres, with a number density of 10 15 / m 3 The crystal structure includes simple cubic structure, complex cubic structure, tetragonal structure, monoclinic structure or close-packed hexagonal structure, and the submicron nucleating agent is coherent or semi-coherent with the Fe-containing phase in common aluminum alloys, and has a good adsorption effect on atoms such as Fe, Mn, Cr, and Si. Example 4

[0031] The present embodiment discloses a composite modifier for casting aluminum alloy and a method for preparing the modifier, which has uniform composition and high stability of the modification effect, can simultaneously modify eutectic Si and Fe-containing compounds, and effectively improves the strength, toughness and fatigue resistance of the alloy. The components and weight percentages of the composite modifier for aluminum alloy are: Ti 5%, B 3%, C0.8%, Ni 1.0%, Nd 1.0%, Hf 0.3%, Zr 0.2%, Ca 0.1%, Sr 0.1%, Bi 0.1%, and the rest is Al.

[0032] The preparation method of the composite modifier for cast aluminum alloy based on the above components in this embodiment comprises the following steps: (1) The aluminum alloy composite modifier with the above components is prepared and smelted. The smelting process is as follows: Introduce high-purity argon or nitrogen for protection; First, pure aluminum is melted and heated to 750°C; Then add Al-10Ti, Al-3B, Al-10Ni, Al-5Nd, and Al-5Zr master alloys, and continue to heat the melt to 1000°C to fully melt the master alloy containing the nucleating agent; Then the melt is cooled to 750°C, Al-50Sn, Al-10Ca, and Al-3Bi master alloys are added, and after the master alloys are fully melted, they are degassed with high-purity argon gas, and then cast to obtain an ingot, with a melt cooling rate of 500K / s; (2) The modifier ingot in step (1) is rolled to obtain a rod, which is then drawn and annealed to obtain a composite modifier.

[0033] The alloy structure obtained in this embodiment is as follows Figure 4 As shown. Through organizational observation, it is found that the two-dimensional morphology of the nucleating agents Al3B, Al3Ti, TiB2, (TiNd)B2, (TiZr)B2, and (TiHf)B2 in the composite modifier includes one or more of polygonal, short rod, or spherical shapes, with a number density of 10 20 / m 3 The crystal structures include simple cubic structure, complex cubic structure, tetragonal structure, monoclinic structure and close-packed hexagonal structure, and the submicron nucleating agent is coherent or semi-coherent with the Fe-containing phase in common aluminum alloys, and has a good adsorption effect on atoms such as Fe, Mn, Cr, and Si.

[0034] The technical contents and technical features of the present invention have been disclosed as above. However, those skilled in the art may still make various substitutions and modifications based on the teachings and disclosures of the present invention without departing from the spirit of the present invention. Therefore, the protection scope of the present invention should not be limited to the contents disclosed in the embodiments, but should include various substitutions and modifications that do not depart from the present invention and are covered by the claims of this patent application.

Claims

1. A composite modifier for cast aluminum alloy, characterized in that: The composite modifier of the cast aluminum alloy includes a submicron nucleating agent; the submicron nucleating agent is selected from two or more of TiC, NiC, Al3B, Al3Ti, TiB2, Al4C3, (TiNd)B2, (TiZr)B2, and (TiHf)B2; Calculated by weight, the cast aluminum alloy composite modifier includes Ti 2%-5%, B 0.1%-3%, C 0.1%-1.0%, Ni 0.2-1.0%, Nd 0.2-1.0%, Hf 0-0.3%, Zr 0-0.1%, Sc0-0.1% and modifier elements, and the rest is Al; the modifier elements are selected from two or more of La, Ce, Y, Sb, Te, Sn, Be, Ca, Sr and Bi elements.

2. The composite modifier for cast aluminum alloy according to claim 1, characterized in that: The size of the submicron nucleating agent is in the range of 50-300 nm.

3. The composite modifier for cast aluminum alloy according to claim 1, characterized in that: The number density of the submicron nucleating agent is 10 15 -10 20 / m 3 .

4. The composite modifier for cast aluminum alloy according to claim 1, characterized in that: The crystal structure of the submicron nucleating agent is selected from one or more of a simple cubic structure, a complex cubic structure, a tetragonal structure, a monoclinic structure and a close-packed hexagonal structure.

5. The composite modifier for cast aluminum alloy according to claim 1, characterized in that: The submicron nucleating agent has a good adsorption effect on Fe, Mn, Cr and Si atoms, and the atoms of the metamorphic elements can be stably adsorbed on the Fe-containing phase and the eutectic Si growth surface.

6. The composite modifier for cast aluminum alloy according to claim 1, characterized in that: The two-dimensional shape of the submicron nucleating agent is selected from one or more of polygonal, short rod and spherical shapes.

7. The composite modifier for cast aluminum alloy according to claim 1, characterized in that: The total addition amount of the modifying elements in the composite modifying agent for cast aluminum alloy is 0.03-0.1%.

8. A method for preparing the composite modifier for cast aluminum alloy according to any one of claims 1 to 7, characterized in that: The steps include: S11: preparing materials using aluminum and a master alloy; the master alloy is selected from a master alloy containing a submicron nucleating agent and a master alloy containing a modifying element; S12: melting and casting the raw materials after batching in step S11 under a high-purity Ar gas protective atmosphere to obtain a composite modifier ingot; S13: rolling the composite modifier ingot into a rod, drawing and annealing the rod to obtain the cast aluminum alloy composite modifier.

9. The preparation method according to claim 8, characterized in that: In step S12, the smelting steps are as follows: S21: melting aluminum and heating it to 750° C., adding a master alloy containing a submicron nucleating agent and heating it to 800-1000° C. to melt the mixture, thereby obtaining a melt; S22: Cooling the melt to 750° C., adding a master alloy containing a modification element to melt, and degassing.

10. The preparation method according to claim 8, characterized in that: In the step S12, the cooling rate of the melt during casting is 200-500K / s.

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