CN121852778A

CN121852778A - High-strength high-toughness ADC12 cast aluminum alloy and preparation method thereof

Info

Publication number: CN121852778A
Application number: CN202511991120.7A
Authority: CN
Inventors: 张晓菊; 桂伟民; 何亮亮
Original assignee: Shaanxi Fast Gear Co Ltd
Current assignee: Shaanxi Fast Gear Co Ltd
Priority date: 2025-12-26
Filing date: 2025-12-26
Publication date: 2026-04-14

Abstract

The invention discloses a high-strength high-toughness ADC12 cast aluminum alloy and a preparation method thereof, and belongs to the technical field of aluminum alloy preparation. The ADC12 cast aluminum alloy comprises the following chemical components, by weight, 9.6% -12.0% of Si, less than or equal to 1.3% of Fe, 1.5% -2.5% of Cu, less than or equal to 0.5% of Mn, less than or equal to 0.3% of Mg, less than or equal to 0.5% of Ni, less than or equal to 1.0% of Zn, less than or equal to 0.2% of Sn, 0.1% -0.3% of Tb, and the balance of aluminum and unavoidable impurity elements. Meanwhile, artificial aging treatment is provided, and the strength is further improved by precipitating a secondary strengthening phase, so that the ADC12 material with low cost, high strength and high toughness is developed, and the requirement of high strength under extreme conditions is met.

Description

High-strength high-toughness ADC12 cast aluminum alloy and preparation method thereof

Technical Field

The invention relates to the technical field of aluminum alloy manufacturing, in particular to a high-strength high-toughness ADC12 cast aluminum alloy and a preparation method thereof.

Background

The ADCl2 die casting aluminum alloy belongs to Al-Si-Cu series alloy, and is one of die casting aluminum alloys with wide application. As a secondary aluminum alloy, ADCl2 die-cast aluminum alloy has an important position in the field of automobile weight reduction by virtue of its excellent castability, corrosion resistance, wear resistance, thermal stability and low density. However, the traditional ADC12 aluminum alloy has relatively low tensile strength (230-280 MPa) and elongation (1-3%), and when the traditional ADC12 aluminum alloy is used for manufacturing parts such as a shell, a bearing cover, a window cover and the like, the bearing capacity and the impact resistance are difficult to meet the requirements of high-strength structural members, and particularly, the traditional ADC12 aluminum alloy is insufficient to completely replace cast iron materials under extreme working conditions like mining areas.

For this reason, related researches on the improvement of the strength of the ADC12 aluminum alloy are also carried out in the prior art, such as the prior patent with publication number of CN 119979933A, which discloses an as-cast high-toughness aluminum alloy and a composite refining modification process thereof, wherein the toughness of the ADC12 material is improved by regulating and controlling the content of alloy elements and adding a composite refining rare earth modifier, the prior patent with publication number of CN 115976356B, which discloses an as-cast high-strength high-toughness die-casting aluminum-silicon alloy and a preparation method thereof, the toughness of the ADC12 material is improved by adopting an AlTi5B1 and Al-10Sr intermediate alloy for refining and modification, the toughness of the ADC12 regenerated aluminum alloy is improved by adding a rare earth Y element for modification, the toughness of the ADC12 regenerated aluminum alloy is improved by adding a proper amount of strontium, samarium and aluminum-based strengthening powder (Si Cp/Al), and the preparation method thereof. The prior art adopts micro alloying technology to improve the toughness of the regenerated aluminum ADC12 material.

Since ADC12 is used as a core cast aluminum alloy in the automotive industry, the cost is obviously increased due to the rising of copper price in recent years, and in addition, the high-end equipment manufacturing field of new energy sources, such as a motor shell, has raised requirements for high strength, high toughness and low cost on the aluminum alloy, the traditional optimization mode is to increase the copper content in ADC12 to improve the strength and toughness of the material, but the pure copper price is high, the increase of copper content can lead to the rising of cost, and meanwhile, the casting performance of the ADC12 aluminum alloy, such as flowability, hot cracking tendency and shrinkage porosity, can be negatively affected due to the excessively high copper content, and meanwhile, the toughness and corrosion resistance can be damaged. Therefore, there is a need to provide an ADC12 cast aluminum alloy with high strength, high toughness and low cost and a method for preparing the same.

Disclosure of Invention

The invention aims to overcome the problems in the prior art and provide a high-strength high-toughness ADC12 cast aluminum alloy and a preparation method thereof, wherein the aluminum alloy has high strength, high toughness and low cost.

The invention provides a high-strength high-toughness ADC12 cast aluminum alloy, which comprises the following chemical components, by weight, 9.6% -12.0% of Si, less than or equal to 1.3% of Fe, 1.5% -2.5% of Cu, less than or equal to 0.5% of Mn, less than or equal to 0.3% of Mg, less than or equal to 0.5% of Ni, less than or equal to 1.0% of Zn, less than or equal to 0.2% of Sn, 0.1% -0.3% of Tb, and the balance of aluminum and unavoidable impurity elements.

Preferably, the iron-containing beta phase is in the form of particles or short rods in the microstructure, and the maximum length of the iron-containing beta phase is less than 2 μm.

Preferably, a characteristic peak of Tb element is detectable in the iron-containing beta phase in EDS spectroscopy.

Preferably, the eutectic silicon phase of the aluminum alloy is punctiform or vermicular.

Preferably, the ADC12 cast aluminum alloy after artificial aging treatment has tensile strength of more than or equal to 400MPa, elongation after fracture of more than or equal to 2.5%, yield strength of more than or equal to 300MPa and hardness of more than or equal to 100HBW.

Preferably, the ADC12 after the artificial aging treatment is used for casting aluminum alloy, and has the tensile strength of 481MPa, the yield strength of 326MPa, the elongation of 3.0% and the hardness of 110HBW.

The invention also provides a preparation method of the high-strength high-toughness ADC12 cast aluminum alloy, which comprises the following steps:

Weighing raw materials according to target components, smelting to obtain aluminum liquid with qualified components, adjusting the temperature of the obtained aluminum liquid to 720-740 ℃, adding an aluminum terbium intermediate alloy for modification treatment, and then refining to obtain refined aluminum liquid, wherein the mass percentage of terbium in the aluminum terbium intermediate alloy is 2-5%;

and (3) casting and forming the refined aluminum liquid to obtain an ingot or casting, and carrying out artificial aging treatment on the ingot or casting for 4-8 hours at 160-200 ℃ and then air cooling.

Preferably, a decalcifying agent is also added at the same time or after the addition of the aluminum terbium master alloy.

The invention also provides a structural member, which comprises the ADC12 cast aluminum alloy or the ADC12 cast aluminum alloy prepared by the preparation method.

Preferably, the structural member is an automobile part comprising a housing, a bearing cover or a window cover, wherein the housing comprises a motor casing.

Compared with the prior art, the invention has the beneficial effects that:

The invention reduces the cost by reducing the content of copper elements, and simultaneously adds trace rare earth terbium elements to refine the structure to improve the strength and the toughness so as to compensate the strength reduction caused by the reduction of the copper elements. Tb is lanthanide rare earth element, and forms intermetallic compound with high melting point and high stability (such as Al3Tb, melting point about 1350 deg.C) with Al, O, etc. when the molten aluminum solidifies, these compound can be used as effective heterogeneous nucleus to obviously refine crystal grain and dendrite of cast structure. Meanwhile, tb atoms which are in solid solution or are biased to the grain boundary can drag the grain boundary to block migration of the Tb atoms in the heat treatment process, so that growth of grains is inhibited, and uniform and fine microstructure is obtained. Tb can also change the form of eutectic silicon to change from coarse plate shape to fine fiber shape or coral shape, thereby greatly improving the strength and plasticity of the alloy. Tb has certain solid solubility in the ADC12 aluminum alloy, and Tb atoms in solid solution can cause lattice distortion to generate a solid solution strengthening effect, so that the mechanical property of the alloy is improved. Compared with Sc, Y, nd, sm, la, ce and the like which are most widely applied at present, the core value of the Tb lanthanide rare earth element used in the invention is in the incomparable precipitation strengthening potential, and the thermal stability of the formed Al ₃ Tb is far higher than that of the precipitated phases such as Al ₃La/Al₃Ce/Al₃ Y and the like, so that the Tb lanthanide rare earth element can keep a tiny dispersion state for a long time at higher temperature. The addition of a small amount of Tb element can change the crystallization condition of the alloy, prevent the growth of crystal grains, and simultaneously enable flaky and needle-shaped eutectic silicon to be changed into spherical grains, so that the size of primary crystal silicon is reduced, and the mechanical property of the alloy is improved.

In addition, the die casting process cannot be strengthened by heat treatment because the housing has pores and pinholes due to high speed and high pressure. The invention provides artificial aging treatment, and the strength is further improved by precipitating a secondary strengthening phase, and the strength meets the requirement of high strength under extreme conditions.

Drawings

FIG. 1 is a drawing of the dimensions of a tensile bar.

Fig. 2 is an ADC12 aluminum alloy microstructure of example 1 and comparative example 2 of the present invention.

Fig. 3 is an EDS elemental surface scan picture of an ADC12 aluminum alloy of example 1 of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. It will be apparent that the described embodiments are some, but not all, embodiments of the invention. All other embodiments, which can be made by a person skilled in the art without creative efforts, based on the described embodiments of the present invention fall within the protection scope of the present invention.

Unless defined otherwise, technical or scientific terms used herein should be given the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The terms "first," "second," and the like, as used herein, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The word "comprising" or "comprises", and the like, is intended to mean that elements or items that are present in front of "comprising" or "comprising" are included in the word "comprising" or "comprising", and equivalents thereof, without excluding other elements or items. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", etc. are used merely to indicate relative positional relationships, and when the absolute position of the object to be described is changed, the relative positional relationships may be changed accordingly.

According to the invention, the ADC12 aluminum alloy with low cost, high strength and high toughness is obtained by reducing the copper (Cu) element content of the ADC12 aluminum alloy, adding a proper amount of low-value rare earth terbium (Tb) and artificially aging, so as to meet the requirements of high-strength aluminum alloy structural parts.

The high-strength aluminum alloy comprises, by weight, 9.6-12.0% of Si, less than or equal to 1.3% of Fe,1.5-2.5% of Cu, less than or equal to 0.5% of Mn, less than or equal to 0.3% of Mg, less than or equal to 0.5% of Ni, less than or equal to 1.0% of Zn, less than or equal to 0.2% of Sn,0.1-0.3% of Tb, and the balance of aluminum and unavoidable impurity elements.

Illustratively, the weight percent of Si in embodiments of the present invention may be 9.61%, 9.73%, 9.81%, 9.90%, 10.12%, 10.16%, 10.52%, 10.82%, 11.10%, 11.32%, 11.51%, 11.84%, 12% or a range of any two of these.

Illustratively, the weight percent of Fe in embodiments of the present invention may be 1.29%, 1.17%, 1.1%, 1.0%, 0.94%, 0.83%, 0.71%, 0.64%, 0.50% or a range of any two of these.

The strengthening phases A1 ₂ Cu and A1 ₄Mg₆Cu₄Si₄ are formed in the aluminum alloy by Cu, the strength and the hardness of the aluminum alloy can be improved through a solid solution strengthening mechanism, but the price of copper is higher, so that the invention achieves the aim of reducing the cost of the ADC12 aluminum alloy by reducing the content of copper elements on the premise of ensuring the mechanical property.

Illustratively, the weight percent of Cu in embodiments of the present invention may be 1.51%, 1.60%, 1.75%, 1.83%, 1.94%, 2.0%, 2.15%, 2.23%, 2.30%, 2.46%, 2.51% or a range of any two of these.

The weight percentage of Mn, mg, ni, zn, sn in the embodiments of the present invention is any value that satisfies the above constraints.

In the embodiment of the invention, the rare earth element is Sc, Y, nd, sm, la, ce and the like which are most widely applied in aluminum alloy modification, and Tb which is used in the invention belongs to lanthanide rare earth element, and the Tb and elements such as Al, O and the like can form intermetallic compounds with high melting point and high stability (such as Al3Tb, the melting point is about 1350 ℃), and the compounds can be used as effective heterogeneous nucleation cores when an aluminum melt is solidified, so that crystal grains and dendrites of an as-cast structure are obviously refined. Meanwhile, tb atoms which are in solid solution or are biased to the grain boundary can drag the grain boundary to block migration of the Tb atoms in the heat treatment process, so that growth of grains is inhibited, and uniform and fine microstructure is obtained. Tb can also change the form of eutectic silicon to change from coarse plate shape to fine fiber shape or coral shape, thereby greatly improving the strength and plasticity of the alloy. Tb has certain solid solubility (although lower) in the ADC12 aluminum alloy, and Tb atoms in solid solution can cause lattice distortion to generate solid solution strengthening effect, so that the mechanical property of the alloy is improved.

Meanwhile, the main functions of Sc, Y, nd, sm, la, ce and the like which are most widely applied at present are to purify melt, modify silicon phase and refine eutectic structure, and the Tb lanthanide rare earth element used in the invention has purification and modification functions, but the core value is in the unparalleled precipitation strengthening potential, and the thermal stability of the formed Al ₃ Tb is far higher than that of the precipitated phases such as Al ₃La/Al₃Ce/Al₃ Y and the like, so that the fine dispersion state can be kept for a long time at higher temperature. The addition of a small amount of Tb element can change the crystallization condition of the alloy, prevent the growth of crystal grains, and simultaneously enable flaky and needle-shaped eutectic silicon to be changed into spherical grains, so that the size of primary crystal silicon is reduced, and the mechanical property of the alloy is improved.

Illustratively, the weight percent of Tb in the present embodiment may be 0.1%, 0.15%, 0.2%, 0.25%, 0.3% or a range of any two of these.

The preparation method provided by the embodiment of the invention comprises the following steps:

The invention reduces the content of reinforcing phases such as A1 ₂ Cu, A1 ₄Mg₆Cu₄Si₄ and the like due to the reduction of the copper content, thereby reducing the mechanical property. Therefore, in order to compensate for the reduction of mechanical properties caused by copper reduction, the invention also carries out artificial aging treatment for 160-200 ℃ and 4-8 hours on the material, so as to promote precipitation of aluminum alloy strengthening phases such as A1 ₂ Cu, A1 ₄Mg₆Cu₄Si₄ and the like, and simultaneously, tb in supersaturated solid solution can be precipitated as nano-scale and dispersed Al3Tb in the aging process. The precipitated phases are coherent with the aluminum matrix, so that dislocation can be extremely effectively pinned and grain boundary movement can be blocked, a very obvious precipitation strengthening effect is generated, and the strength, hardness and heat resistance of the alloy are greatly improved. And taking out for air cooling after the heat preservation is finished. The time and temperature in the manual working efficiency treatment in this embodiment are conclusions obtained through orthogonal tests, and the results show that the temperature is low, the time is short, the reinforced phase is not sufficiently precipitated, and the resource waste is caused by the high temperature and the long time, so that the temperature is 160 ℃ to 200 ℃ and the time is 4 hours to 8 hours, more preferably, the temperature is 185 ℃ and the time is 6 hours in this embodiment.

The invention also provides a structural member, which comprises the ADC12 cast aluminum alloy or the ADC12 cast aluminum alloy prepared by the preparation method, and has excellent yield strength, tensile strength, elongation and hardness. The structural member provided in this embodiment may perform the method provided in the foregoing method embodiment, and its implementation principle and technical effects are similar, which is not described herein in detail.

The following adopts specific embodiments to further explain the technical scheme of the application:

Example 1

In the embodiment, the high-strength high-toughness ADC12 cast aluminum alloy comprises the following chemical components in percentage by weight of Si10.22%, fe1.01%, cu1.83%, mn0.15%, mg0.0263%, ni0.032%, zn0.86%, sn0.046%, tb0.21%, and the balance of aluminum and unavoidable impurity elements.

The preparation method of the high-strength high-toughness ADC12 cast aluminum alloy comprises the following steps:

(1) And (3) proportioning, namely proportioning according to the calculated content of chemical components, and weighing electrolytic aluminum, secondary aluminum, industrial silicon, electrolytic manganese, magnesium, copper and aluminum terbium intermediate alloy (Al-2% -5% Tb).

(2) Smelting, namely putting weighed electrolytic aluminum, reclaimed aluminum, industrial silicon, electrolytic manganese and copper materials into a smelting chamber, smelting for 5-7 hours at 640-680 ℃, mechanically stirring for 2-3 times, standing for more than or equal to 2 minutes each time, and slagging off to ensure that the surface of the aluminum liquid is clean without obvious scum and iron absorption, thus obtaining the aluminum liquid 1.

(3) And (3) component pre-detection, namely taking a sample below 10cm of the liquid level of the aluminum liquid 1, detecting chemical components, and calculating the addition amount of insufficient elements according to the detection result.

(4) And alloying, namely adding the required materials, then keeping the temperature at 760-800 ℃ for 40-50 min, mechanically stirring for 2-3 times, each time being more than or equal to 2min, standing, and removing slag, so that the surface of the aluminum liquid is clean and has no obvious scum, and obtaining the aluminum liquid 2.

(5) And (3) component detection, namely taking a sample below 10cm of the liquid level of the aluminum liquid 2 for chemical component detection, repeating the operation in the step (3) until the detection is qualified if the detection is unqualified, adding a cooling material if the detection is qualified, reducing the smelting temperature to 720-740 ℃, adding an aluminum terbium intermediate alloy, removing a calcium agent, mechanically stirring for 2-3 times, standing for more than or equal to 2min each time, and slagging off to obtain the aluminum liquid 3.

(6) Refining, namely adding a slag removing agent at the temperature of 710-750 ℃, introducing nitrogen, treating for more than 20min, mechanically stirring for 2-3 times, standing for more than or equal to 2min each time, removing slag, immersing, adding magnesium metal, and stirring for more than or equal to 2min to obtain aluminum liquid 4.

(7) And casting, namely standing the aluminum liquid 4 for 15-30 min, and casting into ingots at the casting temperature of 700-730 ℃.

Example 2

The preparation process of the aluminum alloy in this embodiment is the same as that of embodiment 1, except that the high-strength high-toughness ADC12 cast aluminum alloy in this embodiment comprises the following chemical components by weight percent, si10.25%, fe0.96%, cu1.52%, mn0.15%, mg0.0263%, ni0.033%, zn0.88%, sn0.052%, tb0.22%, the balance of aluminum and unavoidable impurity elements, and the balance of aluminum and unavoidable impurity elements.

The preparation method is the same as in example 1.

Example 3

The preparation process of the aluminum alloy in this embodiment is the same as that of embodiment 1, except that the high-strength high-toughness ADC12 cast aluminum alloy in this embodiment comprises the following chemical components by weight percent, si10.23%, fe1.05%, cu2.05%, mn0.15%, mg0.0263%, ni0.031%, zn0.89%, sn0.059%, tb0.25%, and the balance of aluminum and unavoidable impurity elements.

The preparation method is the same as in example 1.

Example 4

The preparation process of the aluminum alloy in this embodiment is the same as that of embodiment 1, except that the high-strength high-toughness ADC12 cast aluminum alloy in this embodiment comprises the following chemical components by weight percent, si10.23%, fe1.01%, cu2.51%, mn0.15%, mg0.0263%, ni0.032%, zn0.90%, sn0.072%, tb0.22%, the balance of aluminum and unavoidable impurity elements, and the balance of aluminum and unavoidable impurity elements.

The preparation method is the same as in example 1.

Example 5

The preparation process of the aluminum alloy in this embodiment is the same as that of embodiment 1, except that the high-strength high-toughness ADC12 cast aluminum alloy in this embodiment comprises the following chemical components by weight percent, si10.26%, fe0.99%, cu1.81%, mn0.15%, mg0.0263%, ni0.029%, zn0.88%, sn0.047%, tb0.12%, the balance of aluminum and unavoidable impurity elements, and the balance of aluminum and unavoidable impurity elements.

The preparation method is the same as in example 1.

Example 6

The preparation process of the aluminum alloy in this embodiment is the same as that of embodiment 1, except that the high-strength high-toughness ADC12 cast aluminum alloy in this embodiment comprises the following chemical components by weight percent, si10.21%, fe1.06%, cu1.85%, mn0.15%, mg0.0263%, ni0.026%, zn0.86%, sn0.055%, tb0.15%, the balance of aluminum and unavoidable impurity elements, and the balance of aluminum and unavoidable impurity elements.

The preparation method is the same as in example 1.

Example 7

The preparation process of the aluminum alloy in this embodiment is the same as that of embodiment 1, except that the high-strength high-toughness ADC12 cast aluminum alloy in this embodiment comprises the following chemical components by weight percent, si10.25%, fe1.02%, cu1.86%, mn0.15%, mg0.0263%, ni0.030%, zn0.86%, sn0.062%, tb0.3%, and the balance of aluminum and unavoidable impurity elements.

The preparation method is the same as in example 1.

In order to verify the mechanical properties of the aluminum ingot obtained by casting in the embodiment of the invention, the aluminum ingot obtained by the preparation in each of the embodiments 1-7 is cut into 200mm long sample blocks along the length direction of the aluminum ingot, the aluminum ingot is processed into a tensile test bar according to the following dimension of the figure 1, the dimension unit in the figure 1 is mm, and the tensile test bar is subjected to man-hour effect treatment, in particular to heat preservation of the test bar with mechanical property detection in a 185 ℃ blast drying oven for 6 hours, so that aluminum alloy strengthening items A1 ₂ Cu, A1 ₄Mg₆Cu₄Si₄ and the like are promoted to be separated out, and the hardness and strength are improved. And taking out for air cooling after the heat preservation is finished. Tensile property (GB/T228.1) and hardness test (GB/T231.1) are carried out on the mechanical property test bar of the ADC12, and performance test data are obtained.

Comparative example 1

In comparative example 1, the ADC12 cast aluminum alloy comprises the following chemical components by weight percent, si10.22%, fe1.01%, cu1.87%, mn0.15%, mg0.0263%, ni0.032%, zn0.86%, sn0.032%, and the balance of aluminum and unavoidable impurity elements.

The preparation of comparative example 1 was the same as that of example 1, except that the starting material did not include the addition of an aluminum terbium master alloy, and that in step (5) no aluminum terbium master alloy was added.

The preparation method comprises the following steps:

(1) And (3) proportioning, namely proportioning according to the calculated content of chemical composition theory, and weighing electrolytic aluminum, secondary aluminum, industrial silicon, electrolytic manganese, magnesium and copper.

(4) And alloying, namely adding the required materials, then keeping the temperature at 760-800 ℃ for 40-50 min, mechanically stirring for 2-3 times, each time being more than or equal to 2min, standing, and skimming to ensure that the surface of the aluminum liquid is clean and no obvious scum exists, thus obtaining the aluminum liquid 2.

(5) And (3) component detection, namely taking a sample below 10cm of the liquid level of the aluminum liquid 2 for chemical component detection, repeating the operation in the step (3) until the detection is qualified if the detection is unqualified, adding a cooling material if the detection is qualified, reducing the smelting temperature to 720-740 ℃, adding a calcium removing agent, mechanically stirring for 2-3 times, standing for more than or equal to 2min each time, and slagging off to obtain the aluminum liquid 3.

(7) And (3) casting, namely standing the molten aluminum 4 for 15-30 min, and casting into ingots at the casting temperature of 700-730 ℃.

The ingot prepared in comparative example 1 was cut out a 200mm long sample along the length direction of the aluminum ingot, and was processed into a tensile test bar according to the following dimensions of fig. 1 for mechanical property detection, while the mechanical property test bar was kept at a temperature of 185 ℃ in a forced air drying oven for 6 hours, to promote precipitation of aluminum alloy strengthening items A1 ₂ Cu, A1 ₄Mg₆Cu₄Si₄, and the like, and to improve hardness and strength. And taking out for air cooling after the heat preservation is finished. Tensile property and hardness are tested on the mechanical property test bars of the ADC12, and performance test data are obtained.

Comparative example 2

In comparative example 2, the ADC12 cast aluminum alloy comprises the following chemical components by weight percent, si10.29%, fe0.73%, cu2.31%, mn0.25%, mg0.26%, ni0.048%, zn0.82%, sn0.027%, and the balance of aluminum and unavoidable impurity elements.

The preparation method of the comparative example 2 is the same as that of the comparative example 1, the ingot prepared in the comparative example 2 is cut into 200mm long sample blocks along the length direction of an aluminum ingot, and is processed into a tensile test bar according to the following dimension shown in fig. 1 for mechanical property detection, and meanwhile, the mechanical property test bar is kept for 6 hours in a 185 ℃ blast drying oven, so that aluminum alloy strengthening items A1 ₂ Cu, A1 ₄Mg₆Cu₄Si₄ and the like are promoted to be separated out, and the hardness and strength are improved. And taking out for air cooling after the heat preservation is finished. Tensile property and hardness are tested on the mechanical property test bars of the ADC12, and performance test data are obtained.

Comparative example 3

In comparative example 3, the ADC12 cast aluminum alloy comprises the following chemical components by weight percent, si10.32%, fe0.75%, cu2.31%, mn0.25%, mg0.24%, ni0.046%, zn0.82%, sn0.037%, and the balance of aluminum and unavoidable impurity elements. The preparation method of comparative example 3 was the same as that of comparative example 1.

Compared with comparative example 2, the difference is that the ingot prepared in comparative example 3 was cut into 200mm long pieces along the length direction of the aluminum ingot, and was processed into tensile bars for mechanical property detection according to the following dimensions of fig. 1. No artificial ageing treatment was performed. And directly testing the tensile property and the hardness of the mechanical property test bar of the ADC12 to obtain performance test data.

Comparative example 4

In comparative example 4, the ADC12 cast aluminum alloy comprises the following chemical components, by weight, si19.69%, fe0.77%, cu1.48%, mn0.21%, mg0.22%, ni0.037%, zn0.65%, sn0.033%, and the balance of aluminum and unavoidable impurity elements. The preparation method of comparative example 4 was the same as that of comparative example 1.

The ingot prepared in comparative example 4 was cut into 200mm long pieces along the length direction of the aluminum ingot, and was processed into tensile bars according to the following dimensions of fig. 1 for mechanical property detection, while the mechanical property bars were kept at a temperature of 185 ℃ in a forced air drying oven for 6 hours, so as to promote precipitation of aluminum alloy strengthening items A1 ₂ Cu, A1 ₄Mg₆Cu₄Si₄, and the like, and to improve hardness and strength. And taking out for air cooling after the heat preservation is finished. Tensile property and hardness are tested on the mechanical property test bars of the ADC12, and performance test data are obtained.

Comparative example 5

In comparative example 5, the ADC12 cast aluminum alloy comprises the following chemical components by weight percent, si19.69%, fe0.77%, cu1.48%, mn0.21%, mg0.22%, ni0.032%, zn0.65%, sn0.035%, and the balance of aluminum and unavoidable impurity elements. The preparation method of comparative example 5 was the same as that of comparative example 1. The ingot prepared in comparative example 5 was cut out in 200mm long pieces along the length of the ingot, and was processed into tensile bars for mechanical property detection according to the following dimensions of FIG. 1.

Compared with comparative example 4, the ingot prepared in comparative example 5 was cut into 200mm long pieces along the length of the aluminum ingot, and was processed into tensile bars for mechanical property detection according to the following dimensions of FIG. 1. No artificial ageing treatment was performed. And directly testing the tensile property and the hardness of the mechanical property test bar of the ADC12 to obtain performance test data.

Table 1 specification of the composition of the ADC12 aluminum alloy of each of the examples and comparative examples (mass fraction, wt.%)

Tensile properties and hardness test results of the mechanical property test bars of ADC12 prepared in examples 1 to 7 and comparative examples 1 to 5 are shown in Table 2.

Table 2 mechanical properties of ADC12 aluminum alloys for each of the examples and comparative examples

From the test results, the overall performance of examples 1-7 is superior to that of each comparative example, particularly the tensile strength and the yield strength, the tensile strength of the ADC12 aluminum alloy of example 1 is improved by about 72% relative to that of the ADC12 aluminum alloy of comparative example 1, the yield strength is improved by about 79%, the elongation is 2 times that of comparative example 1, and the hardness is also improved by about 20%.

The difference between comparative example 2 and comparative example 3 is whether the mechanical property test bar for mechanical property test is artificially aged, wherein comparative example 2 is artificially aged, comparative example 3 is not artificially aged, the mechanical property test bar is directly subjected to property test, and the result shows that the mechanical property of comparative example 2 is better, the difference between comparative example 4 and comparative example 5 is whether the mechanical property test bar for mechanical property test is artificially aged, wherein comparative example 4 is artificially aged, comparative example 5 is not artificially aged, the mechanical property test bar is directly subjected to property test, and the result shows that the mechanical property of comparative example 4 is better, the maximum difference between comparative example 2 and comparative example 4 is different from Cu content, the performance test result of comparative example 2 is better than that of comparative example 4 from the test result, but the cost is higher due to the high Cu content.

Fig. 2 is a metallographic microstructure of the ADC12 aluminum alloy of example 1 and comparative example 1, in which the pre-modification corresponds to the comparative example in the drawing, and the post-modification corresponds to example 1 in the drawing, and it can be seen from the drawing that the terbium element modification effect is remarkable, the structure before modification (comparative example 1) is in coarse dendrite shape, needle-like eutectic silicon is irregularly distributed, the dendrite structure after modification (example 1) is refined into denser grains, the α dendrite and the eutectic silicon are uniformly distributed, and the eutectic silicon is in a punctiform or vermiform shape, thereby improving the uniformity of the components and the structure, and greatly improving the mechanical properties of the material.

TABLE 3 example 1ADC12 aluminum alloy EDS elemental test results (wt.%)

In ADC12 cast aluminum alloy, fe-containing beta phase is Al-Si-Fe ternary eutectic or hypereutectic product (beta-AlFeSi), which is typically characterized by coarse needle-like and flake-like morphology (length-diameter ratio > 10), and the phases are hard and brittle, have poor toughness and are easy to be stress concentration sources, so that the elongation and strength of the aluminum alloy are obviously reduced. Fig. 3 shows the result of element distribution characterization on the surface of the modified ADC12 aluminum alloy (example 1) by using a scanning electron microscope equipped with EDS, it can be seen that after the ADC12 material is subjected to Tb treatment, tb element is mainly enriched in Fe-containing phase, and by reacting with Al, fe, si to generate rare earth aluminum iron silicon compounds such as TbAlFeSi, tb ₃AlFeSi₃, etc., as an effective nucleation base of β phase and pinning the growth interface thereof, the final Fe-containing β phase is converted into fine grains and short bars (length <2 μm), so that the size of the original large-size β brittle phase is finer and more stable, the splitting effect of the original brittle β phase to the matrix can be effectively reduced, the stress concentration coefficient can be reduced, and thus the strength and toughness can be effectively improved.

Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. A high-strength high-toughness ADC12 cast aluminum alloy is characterized by comprising the following chemical components, by weight, 9.6% -12.0% of Si, less than or equal to 1.3% of Fe, 1.5% -2.5% of Cu, less than or equal to 0.5% of Mn, less than or equal to 0.3% of Mg, less than or equal to 0.5% of Ni, less than or equal to 1.0% of Zn, less than or equal to 0.2% of Sn, 0.1% -0.3% of Tb, and the balance of aluminum and unavoidable impurity elements.

2. The cast aluminum alloy of claim 1, wherein the iron-containing beta phase is in the form of particles or short rods in the microstructure, and the maximum length of the iron-containing beta phase is less than 2 μm.

3. The high strength, high toughness ADC12 cast aluminum alloy according to claim 1, wherein a characteristic peak of Tb element is detectable in the iron-containing β phase in EDS spectroscopy.

4. The high strength, high toughness ADC12 cast aluminum alloy according to claim 1, wherein the eutectic silicon phase of the aluminum alloy is punctiform or vermicular.

5. The high-strength high-toughness ADC12 cast aluminum alloy according to claim 1, wherein the tensile strength of the ADC12 cast aluminum alloy after artificial aging treatment is more than or equal to 400MPa, the elongation after fracture is more than or equal to 2.5%, the yield strength is more than or equal to 300MPa, and the hardness is more than or equal to 100HBW.

6. The cast aluminum alloy of claim 5, wherein the tensile strength is 481MPa, the yield strength is 326MPa, the elongation is 3.0%, and the hardness is 110HBW.

7. The method for producing a cast aluminum alloy for high-strength and high-toughness ADC12 according to claim 1, comprising the steps of:

8. The method for producing a cast aluminum alloy for high-strength and high-toughness ADC12 according to claim 7, wherein a decalcifying agent is further added simultaneously with or after the addition of said aluminum terbium intermediate alloy.

9. A structural member comprising the ADC12 cast aluminum alloy according to any one of claims 1 to 6, or the ADC12 cast aluminum alloy produced by the production method according to any one of claims 7 to 8.

10. The structural member of claim 9 wherein the structural member is an automotive component comprising a housing, bearing cap or window cap.