RU2826211C2 - Articles from highly plastic composite material based on modified aluminum alloy and method of their preparation - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to a method of producing an article from a highly plastic composite material based on a modified aluminum alloy. Method of producing articles from modified aluminum alloy consists of the following steps: step S1—preparation of molten aluminum alloy; step S2—preparation of a modifier; step S3—in an inert gas atmosphere, a modifier for melting is added to the molten aluminum alloy to obtain a melt of the modified aluminum alloy, wherein the amount of said modifier is 0.4–0.6 wt.% of the total amount of molten aluminum alloy; step S4—casting is performed to obtain workpieces from a modified aluminum alloy; stage S5—heat treatment of cast blanks. Heat treatment includes solid solution treatment with heating of workpieces to 530–550 °C and holding for 120–300 min; treatment by quenching in water; aging treatment, wherein the workpieces are held at temperature of 110–140 °C for 120–240 minutes, then the temperature is increased to 160–200 °C and held for 20–60 minutes. Then the workpieces are cooled to room temperature.

EFFECT: obtaining highly plastic articles from composite material based on modified aluminum alloy.

6 cl, 1 dwg, 3 tbl

Description

Field of technology to which the invention relates

The present invention relates to the field of alloyed materials and the technology for their preparation and, in particular, to products made of highly plastic composite material based on a modified aluminum alloy and a method for their preparation.

State of the art

Aluminum alloy is a structural metal material widely used in such fields as aviation, astronautics, automobile manufacturing, mechanical engineering, shipbuilding, chemical industry, etc. Cast aluminum alloy has such characteristics as optimal casting fluidity and air tightness, low shrinkage rate and low susceptibility to thermal cracking, etc. This material is the most preferable in the production of lightweight wheel rims.

However, the demands of consumers for aluminum alloys are becoming more and more stringent. In this regard, it is necessary not only to maintain the light weight of the product, but also to ensure a certain strength, especially in the field of auto parts and industrial production. In addition, when producing aluminum alloy wheel parts, it is necessary to ensure medium strength and higher plasticity of the products in order to avoid instantaneous destruction of the wheel in the event of a frontal or side collision (within the design load-bearing capacity).

In view of this, it was proposed to use modifiers to modify aluminum alloys, such as aluminum-strontium ligature, as well as the use of aluminum alloy refining technology using refining agents. However, traditional modification still does not allow obtaining ideal strength and ductility of products. On this basis, studies were conducted on the heat treatment of cast aluminum alloy. However, due to the difference in components used during the preparation of aluminum alloy products, the stages of heat treatment also differ. The existing heat treatment methods require high temperatures, high energy consumption, a huge amount of time and high costs. Since interconversion and precipitation of each phase does not occur during processing at a higher temperature, this leads to unevenness in the mechanical properties of the alloy.

In this regard, there is an urgent need to provide manufacturing technologies aimed at improving the plasticity and mechanical strength of aluminum alloy products.

The essence of the invention

Based on the above, the present invention provides products made of a highly plastic composite material based on a modified aluminum alloy and a method for their preparation aimed at improving the plasticity and mechanical strength of products made of an aluminum alloy.

To solve the above-mentioned problems, the following technical solutions are used in the present invention:

a method for producing articles from a highly plastic composite material based on a modified aluminum alloy in accordance with an embodiment of the first aspect of the present invention consists of the following steps:

stage S1 - preparation of molten aluminum alloy;

stage S2 - preparation of the modifier;

wherein the above-mentioned modifier is a combination of a rare earth aluminum alloy, an aluminum-strontium ligature, an aluminum-titanium ligature, or an aluminum-titanium-boron ligature,

or the above-mentioned modifier is a combination of a composite rare earth aluminum alloy, an aluminum-titanium ligature or an aluminum-titanium-boron ligature, the above-mentioned composite rare earth aluminum alloy contains strontium, titanium or titanium-boron and rare earth metals,

the rare earth metals in the above-mentioned rare earth aluminum alloy and composite rare earth aluminum alloy are any one or more of lanthanum, cerium and yttrium;

stage S3 - in an inert gas atmosphere, a smelting modifier is added to the above-mentioned aluminum alloy melt to obtain a modified aluminum alloy;

step S4 - casting is carried out using the above-mentioned modified aluminum alloy to obtain casting molds made of modified aluminum alloy;

step S5 - heat treatment of casting molds made of the above-mentioned modified aluminum alloy is carried out, where the above-mentioned heat treatment process includes:

solid solution treatment - casting molds made of the above-mentioned modified aluminum alloy are heated to 530 - 550°C and held for 120 - 300 minutes;

water quenching treatment - casting molds made of the above-mentioned modified aluminum alloy after solid solution treatment are placed in a water bath at a temperature of 60 - 70°C and quenched with water for 2 - 4 minutes;

aging treatment - aluminum alloy casting molds are held at a temperature of 110 - 140°C for 120 - 240 minutes, then the holding temperature is increased to 160 - 200°C and the casting molds are held for 20 - 60 minutes, after which the casting molds are cooled to room temperature until products are obtained from a highly plastic composite material based on a modified aluminum alloy.

The above mentioned stage S1 includes:

ensuring the availability of aluminum alloy ingots;

removal of scale from the surface of ingots made of the above-mentioned aluminum alloy, cleaning and drying;

melting aluminum alloy ingots after drying, refining, removing slag to obtain the above-mentioned aluminum alloy melt;

Moreover, the composition of the ingots from the above-mentioned aluminum alloy is a hypoeutectic aluminum alloy or a eutectic aluminum alloy.

According to some embodiments of the present invention, the above-mentioned modifier is a combination of a rare earth aluminum alloy, an aluminum-strontium ligature, an aluminum-titanium ligature, or an aluminum-titanium-boron ligature, wherein the above-mentioned aluminum-strontium ligature is added separately from the above-mentioned aluminum-titanium or aluminum-titanium-boron ligature;

the above-mentioned rare earth aluminum alloy is added first or added together with the ligature, which is added first or added in the interval between the addition of the above-mentioned aluminum-strontium ligature, aluminum-titanium ligature or aluminum-titanium-boron ligature.

The above mentioned stage S3 includes:

step S301 - adding the above-mentioned rare earth aluminum alloy to the above-mentioned aluminum alloy melt and melting to obtain a first uniformly mixed melt;

step S302 - adding the above-mentioned aluminum-strontium ligature to the above-mentioned first uniformly mixed melt and continuing the melting to obtain a second uniformly mixed melt;

step S303 - adding the above-mentioned aluminum-titanium or aluminum-titanium-boron ligature to the above-mentioned second uniformly mixed melt and continuing melting to obtain the second above-mentioned modified aluminum alloy.

According to some other embodiments of the present invention, the above-mentioned modifier is a combination of a composite rare earth aluminum alloy, an aluminum-titanium or aluminum-titanium-boron master alloy, wherein the above-mentioned step S3 comprises:

step S310 - adding the above-mentioned composite rare earth aluminum alloy to the above-mentioned aluminum alloy melt to obtain a fourth uniformly mixed melt;

step S320 - adding the above-mentioned aluminum-titanium or aluminum-titanium-boron ligature to the above-mentioned fourth uniformly mixed melt and continuing the melting to obtain the second above-mentioned modified aluminum alloy;

wherein the method for preparing the above-mentioned composite rare earth aluminum alloy comprises:

step S211 - ensuring the presence of the above-mentioned aluminum melt;

step S212 - providing an aluminum-strontium ligature, an aluminum-titanium ligature or an aluminum-titanium-boron ligature and a rare earth aluminum alloy, wherein the rare earth metals in the aforementioned rare earth aluminum alloy are one or more elements such as lanthanum, cerium and yttrium;

Step S213: in an inert gas atmosphere, the above-mentioned rare earth aluminum alloy, aluminum-strontium ligature, aluminum-titanium ligature or aluminum-titanium-boron ligature are successively added to the above-mentioned aluminum alloy for smelting to obtain the above-mentioned composite rare earth aluminum alloy.

The above-mentioned modifier accounts for 0.4 - 0.6 wt.% of the total amount of the above-mentioned modified aluminum alloy, and the mass ratio of the above-mentioned rare earth metal: strontium: titanium or boron is 1: (0.1 - 1.2): (0.1 - 1.2).

At stage S5, the heating rate during solid solution processing is adjusted within the range of 1.5 - 3°C/min, and the holding time is adjusted within 120 - 180 min.

The above-mentioned solution treatment, water quenching treatment and aging treatment are continuous processes, and the above-mentioned water bath is a circulating water bath. After water quenching treatment and before aging treatment, the temperature of the modified aluminum alloy molds is maintained at above 55°C.

At the stage of processing by the aging method, the holding temperature from 110 - 140°C to 160 - 200°C is increased at a heating rate of 2-4°C/min; after heating, the casting molds are cooled naturally to room temperature.

The articles made of highly plastic composite material based on modified aluminum alloy according to the embodiment of the second aspect of the present invention are obtained by the above-mentioned preparation method described in any of the above embodiments. The tensile strength of the articles made of highly plastic composite material based on modified aluminum alloy is 280 MPa and above, the yield strength is 200 MPa and above, and the elongation coefficient is 12% and above.

The above-mentioned technical solution of the present invention provides at least one of the following positive results:

in accordance with the method for producing articles from a highly plastic composite material based on a modified aluminum alloy described in the embodiments of the present invention, the modification of the aluminum alloy is performed by adding rare earth metals, and the treatment of the casting articles is carried out in combination with a special heat treatment technology. Thanks to these processes, the plasticity (elongation coefficient) is significantly improved, the risk of brittle cracks is reduced, and the mechanical strength of the articles is increased, which meets the requirements of such areas as aviation, astronautics, automobile manufacturing, etc.

Brief description of graphic materials

Fig. 1 shows images of the metallographic structure of aluminum alloy products at different stages, among them, (a) is an image of aluminum alloy A356 before heat treatment, (b) is an image of aluminum alloy A356 after heat treatment, (c) is an image of aluminum alloy after modification of composite materials and before heat treatment, indicated in embodiment 1, (d) is an image of aluminum alloy after modification of composite materials and heat treatment, indicated in embodiment 1.

Detailed description of embodiments

In order to make the problem of the invention, the ways of solving it and the advantages of the present invention more clear, the technical solutions and embodiments of the present invention will be described in detail below. It should be understood that only a part of the embodiments is presented in this description. All other embodiments obtained by specialists in the art based on the described embodiments of the present invention fall within the scope of protection of the present invention.

Technical or scientific terms used in the present invention shall have the standard meanings understood by those skilled in the art to which the present invention pertains, unless otherwise indicated. "First," "second," and other words used in the present invention do not indicate any order, quantity, or importance, but are used only to distinguish components. Similarly, words such as "one element" or "one" do not indicate a limitation in quantity, but indicate that there is at least one element.

Below, a method for producing articles from a highly plastic composite material based on a modified aluminum alloy in accordance with embodiments of the present invention is described in detail.

The method for preparing articles from a highly plastic composite material based on a modified aluminum alloy in accordance with embodiments of the present invention consists of the following steps:

Stage S1 - preparation of aluminum melt

In other words, first an aluminum melt is prepared.

It should be noted that to prepare aluminum melt, it is necessary to heat commercially available ingots of high-purity aluminum alloy. In addition, it is also possible to clean the ingots of aluminum alloy. The cleaning process may consist of the following stages:

stage S11 - preparation of aluminum alloy ingots;

stage S12 - removal of scale from the surface of aluminum alloy ingots;

stage S13 - cleaning and drying of aluminum alloy ingots after removing the above-mentioned scale;

stage S14 - melting the above-mentioned aluminum alloy ingots after drying to obtain the initial melt;

step S15 - refining the above-mentioned feed melt to obtain the above-mentioned aluminum melt.

In other words, scale and slag are first removed from the surface of aluminum alloy ingots, then after drying, the aluminum alloy ingots are melted to obtain the initial melt, and then the initial melt is refining. A detailed description of the refining process will be provided below.

After the above purification, unwanted impurities such as Fe, oxides, etc. can be removed. The removal of impurities is effective for further improving the modification and refining of rare earth alloys.

It should be added here that Fe and its oxides can be removed by adding, for example, manganese or an aluminum-manganese alloy, which are used to remove slags formed on the surface.

As a matrix for modification, i.e., an aluminum melt, an aluminum-magnesium alloy, an aluminum-silicon alloy, an aluminum-silicon-magnesium alloy and other alloys, which are not specifically limited by the present invention, can be used, for example.

Stage S2 - preparation of the modifier

The above-mentioned modifier is a combination of a rare earth aluminum alloy, an aluminum-strontium ligature, an aluminum-titanium ligature or an aluminum-titanium-boron ligature, or the above-mentioned modifier is a combination of a composite rare earth aluminum alloy, an aluminum-titanium ligature or an aluminum-titanium-boron ligature,

the above-mentioned composite rare earth aluminum alloy contains strontium, titanium or titanium-boron and rare earth metals,

the rare earth metals in the above-mentioned rare earth aluminum alloy and composite rare earth aluminum alloy are any one or more elements such as lanthanum, cerium and yttrium.

In other words, there are two ways of implementation:

Implementation method 1:

The above mentioned modifier is a combination of rare earth aluminum alloy, aluminum-strontium ligature, aluminum-titanium ligature or aluminum-titanium-boron ligature.

Among them, the above-mentioned aluminum-strontium ligature is a modifier, and the above-mentioned aluminum-titanium or aluminum-titanium-boron ligature is a refining agent. In other words, the most common modifiers and refining agents can be used.

Commercially available materials can be used as the above-mentioned modifier and/or refining agent, or strontium, titanium and titanium boron can be measured out and melted in aluminum melt to obtain a homogeneous alloy.

In addition, in addition to the common modifiers and refining agents, rare earth aluminum alloys are also used to overcome the limitations associated with mechanical properties caused by the "poisoning" reaction between the modifiers and refining agents. Considering the presence of strontium in the modifier and titanium and boron in the refining agent, the IIIB group elements with an intermediate electron structure can be selected as rare earth metals in the rare earth aluminum alloy. Considering their stability, resources and other aspects, it is preferable to use one or more elements such as yttrium and cerium from the lanthanide group. For example, one or more of commercially available Al-10Ce, Al-20Ce, Al-20La, Al-10La, Al-20Y and Al-10Y alloys can be used as the rare earth aluminum alloy.

In addition, rare earth aluminum alloy can also be made independently, for example, you can use the following preparation method:

in an inert atmosphere, a rare earth metal or the above-mentioned ligature with rare earth metals is added to the above-mentioned aluminum melt, then heating and simultaneous mixing of the contents is carried out until complete melting;

after complete melting, the contents continue to stand for 10 - 20 minutes until a homogeneous state is achieved;

then the homogeneous melt is refined;

After refining, the alloy is left to stand for a specified period of time, and then cast to obtain the above-mentioned rare earth aluminum alloy.

Commercially available high-purity aluminum ingots can be used for aluminum melt, and the corresponding treatment can be performed on the high-purity aluminum ingots similar to the refining treatment of aluminum alloy ingot. The details are not described here.

In addition, for commercially available aluminum-strontium master alloy, aluminum-titanium master alloy or aluminum-titanium-boron master alloy, rare earth aluminum alloy, the processes such as scale removal, ultrasonic cleaning and refining can be carried out sequentially. In this way, unwanted impurities and oxides can be removed, which can effectively affect the modification and refining process of composite rare earth alloy.

Implementation method 2:

The above mentioned modifier is a combination of rare earth aluminum alloy, aluminum-titanium or aluminum-titanium-boron ligature.

The composite rare earth aluminum alloy can be obtained by smelting and refining the above-mentioned rare earth aluminum alloy, aluminum-strontium ligature, aluminum-titanium or aluminum-titanium-boron ligature, and aluminum melt.

For example, the method for preparing the above-mentioned composite aluminum alloy includes:

stage S211 - preparation of aluminum melt;

step S212 - preparing an aluminum-strontium ligature, an aluminum-titanium ligature or an aluminum-titanium-boron ligature and a rare earth aluminum alloy, wherein the rare earth metals in the aforementioned rare earth aluminum alloy are one or more elements such as lanthanum, cerium and yttrium;

step S213 - in an inert gas atmosphere, the above-mentioned aluminum-rare earth metal ligature, aluminum-strontium ligature, aluminum-titanium ligature or aluminum-titanium-boron ligature are added to the above-mentioned aluminum melt to obtain the above-mentioned composite rare earth alloy.

The above-mentioned aluminum-strontium ligature is added separately from the above-mentioned aluminum-titanium or aluminum-titanium-boron ligature, the above-mentioned rare earth aluminum alloy is added before the above-mentioned aluminum-strontium ligature, aluminum-titanium or aluminum-titanium-boron ligature or is added together with the ligature, which is added first or is added in the interval between the addition of the above-mentioned aluminum-strontium ligature, aluminum-titanium or aluminum-titanium-boron ligature.

Preferably, the above-mentioned rare earth aluminum alloy, aluminum-strontium ligature, aluminum-titanium ligature, or aluminum-titanium-boron ligature are successively added to the above-mentioned aluminum melt at certain intervals.

Step S3 - in an inert gas atmosphere, a smelting modifier is added to the above-mentioned aluminum melt to obtain a modified aluminum alloy

In other words, after preparing the aluminum melt and the modifier, the modifier is added to the aluminum melt in an inert gas atmosphere to produce a modified aluminum alloy.

According to the production method according to the embodiment of the present invention, a rare earth metal is introduced into the modifier, so that the mutual poisoning effect between the modifier and the refining agent is largely overcome, the additive amount of the modifier and the refining agent can be increased, and the effect of modification and refining can be enhanced.

For the modifier of the two combinations above, the smelting process shown below is carried out.

The above mentioned modifier is a combination of rare earth aluminum alloy, aluminum-strontium ligature, aluminum-titanium ligature or aluminum-titanium-boron:

in particular, for carrying out the pre-treatment of each rare earth aluminum alloy, aluminum-strontium ligature, aluminum-titanium ligature or aluminum-titanium-boron ligature, reference may be made to step S2.

In the case of using this combination, in which the above-mentioned aluminum-strontium ligature is added separately from the above-mentioned aluminum-titanium or aluminum-titanium-boron ligature, the above-mentioned rare earth aluminum alloy is added first or is added together with the ligature, which is added first or is added in the interval between the addition of the above-mentioned aluminum-strontium ligature, aluminum-titanium ligature or aluminum-titanium-boron ligature.

It is more preferable when stage S3 also includes:

step S301 - adding the above-mentioned rare earth aluminum alloy to the above-mentioned aluminum melt and melting to obtain a first uniformly mixed melt;

step S302 - adding the above-mentioned aluminum-strontium ligature to the above-mentioned first uniformly mixed melt and continuing melting to obtain a second uniformly mixed melt;

step S303 - adding the above-mentioned aluminum-titanium or aluminum-titanium-boron ligature to the above-mentioned second uniformly mixed melt and continuing melting to obtain the second above-mentioned modified aluminum alloy.

In other words, first the added rare earth aluminum alloy is melted, then at certain intervals the aluminum-strontium ligature used as a modifier and the aluminum-titanium or aluminum-titanium-boron ligature used as a refining agent are successively added. By adding these components, it is possible to solve the problem associated with the toxic effect of strontium and boron, and also to obtain a more refined, more homogeneous and having higher mechanical properties modified aluminum alloy.

In addition, if the above-mentioned modifier is a combination of a rare earth aluminum alloy, an aluminum-titanium ligature, or an aluminum-titanium-boron ligature, the above-mentioned step S3 comprises:

step S310 - adding the above-mentioned composite rare earth aluminum alloy to the above-mentioned aluminum alloy melt to obtain a fourth uniformly mixed melt;

step S320 - adding the above-mentioned aluminum-titanium or aluminum-titanium-boron ligature to the above-mentioned fourth uniformly mixed melt and continuing melting to obtain the second above-mentioned modified aluminum alloy.

In other words, if the rare earth aluminum alloy, modifier, refining agent and aluminum are melted in advance to obtain the composite rare earth aluminum alloy, then adding all the components to the above-mentioned aluminum melt can be done at one time. Naturally, considering the fact that abnormal grain growth may occur during high-temperature melting, which is not conducive to improving the mechanical properties of products, it is preferable that when the composite rare earth aluminum alloy is completely melted and mixed with the aluminum alloy, a refining agent, that is, aluminum-titanium ligature or aluminum-titanium-boron ligature, is additionally added to regulate grain growth.

In this case, the amount of the added modifier is calculated in accordance with the requirements for the use and content of active components in the ligature. As an example, let us take the following situation: when adding components to a composite rare earth alloy (the mass ratio of the total volume of rare earth elements contained: strontium: titanium or titanium and boron = 1: (0.05 - 1.2): (0.0001 - 1)) the preferred amount of the above-mentioned modifier is 0.4 - 0.6% by weight of the total volume of the modified aluminum alloy.

Refining at any of the above stages, that is, refining in the process of refining the aluminum melt, refining in the process of preparing the rare earth aluminum alloy, and refining each melt in the composite rare earth aluminum alloy, can be carried out as follows:

flux is added to the melt by blowing it with an inert gas and it is kept for 3-10 minutes, then a slag remover is added and it is stirred for 5-10 minutes to remove the slag formed on the surface.

The volume of added flux is 0.1 - 0.3% of the mass of the added melt, and the volume of added slag remover is 0.1 - 0.3% of the mass of the added melt;

The components of the above flux, calculated according to weight:

10-15 parts potassium chloride, 15-25 parts sodium chloride, 8-15 parts calcium fluoride, 15-25 parts sodium carbonate, 8-12 parts sodium sulfate, 10-20 parts sodium fluoroaluminate, 8-12 parts hexachloroethane;

The components of the above mentioned slag remover, calculated according to weight:

25-30 parts sodium chloride, 25-30 parts potassium chloride, 5-10 parts sodium carbonate, 5-10 parts sodium sulfate, 1-5% sodium fluoroaluminate, 5-10 parts sodium fluorosilicate, 5-10 parts calcium fluoride, 1-5 parts potassium nitrate, 5-10 parts potassium fluorosilicate.

By monitoring the hydrogen content in the melt, it is possible to determine whether the refining process is continuing. In the present invention, the hydrogen content is determined by measuring the density of the melt, that is, the closer the density of the melt is to the theoretical value (depending on the components contained in the alloy, the density may vary slightly and is about 2.7 g / cm ³ ), the lower the hydrogen content in the melt. For example, the following aspects can be used as a guide: if the density of the melt is less than 2.65 g / cm ³ , this indicates that the above-mentioned refining process needs to be carried out; if the density of the melt is greater than or equal to 2.65 g / cm ³ , this indicates that the above-mentioned refining process does not need to be carried out or the above-mentioned refining process needs to be stopped.

Step S4 - casting using the above-mentioned modified aluminum alloy to obtain modified aluminum alloy casting molds.

In other words, after melting, the resulting modified aluminum alloy is poured into molds to produce casting molds made of modified aluminum alloy.

A specific casting process may use a common casting technology, therefore a detailed description of this process will be omitted.

Stage S5 - heat treatment of casting molds made of the above-mentioned modified aluminum alloy

After obtaining casting molds from aluminum alloy, in order to further increase the mechanical strength of the products, the inventors, based on repeated research, developed a corresponding method of heat treatment.

In particular, the above-mentioned heat treatment method includes:

solid solution processing - casting molds made of the above-mentioned aluminum alloy are heated to 530 - 550°C and held for 120 - 300 minutes;

water quenching treatment - casting molds made of modified aluminum alloy after solid solution treatment are placed in a water bath at a temperature of 60 - 70°C and quenched with water for 2 - 4 minutes;

aging treatment - aluminum alloy casting molds are held at a temperature of 110 - 140°C for 120 - 240 minutes, then the holding temperature is increased to 160 - 200°C and the casting molds are held for 20 - 60 minutes, after which the casting molds are cooled to room temperature until products are obtained from a highly plastic composite material based on a modified aluminum alloy.

In other words, for aluminum alloy casting molds, such treatments as solid solution treatment, water quenching treatment and aging treatment are carried out sequentially.

The above-described solid solution treatment is designed so that the stress caused by the cooling rate of the casting due to such reasons as the structure of the casting (such as uneven wall thickness and thick wall transition) during crystal solidification can be eliminated; the mechanical strength and hardness of the alloy can be improved, and the metallographic structure of the alloy can be improved; intercrystalline segregation and component segregation can be eliminated, so that the structure can be uniform.

In addition, due to the above-mentioned water quenching treatment, the castings are quickly cooled, due to which the strengthening components are maximally dissolved in the alloy, and then stabilized and maintained at room temperature.

Due to the above-mentioned aging treatment, the increase in temperature and time causes the recombination of atoms in the crystal lattice of the supersaturated solid solution, which forms a region enriched with solute atoms (called the G-PI region). When the G-PI region disappears, the atoms of the second phase segregate according to a certain law, forming the G-PII region, a metastable second phase (transition phase). A large number of G-PII regions are interconnected with a small number of metastable phases, the metastable phase is transformed into a stable and second phase for the aggregation of substances.

According to the preparation method of the present invention, a low-temperature aging method is first used, in which more phase transitions occur in the GP region and the β1 region, which ensures a sufficient elongation coefficient.

It is preferable that the heating rate in the solution treatment is controlled within the range of 1.5 - 3°C/min, and the holding time is 120 - 180 min. By adjusting the heating rate and holding time in the solution treatment, it is possible to further increase the rose-shaped α-Al phase and the ball-shaped α-Al phase, and also to refine the primary α-Al phase and reduce the amount of dendrites.

The above-mentioned solution treatment, water quenching treatment and aging treatment are continuous processes, and the above-mentioned water bath is a circulating water bath. After the water quenching treatment and before the aging treatment, the temperature of the modified aluminum alloy mold is maintained at above 55°C. Through continuous treatment, not only can production efficiency be improved, but also unnecessary defects caused by interruption of the process can be avoided. In addition, by controlling the minimum temperature for a certain period of time, defects caused by rapid cooling can be avoided.

At the stage of the above-mentioned aging treatment, the holding temperature from 110 - 140°C to 160 - 200°C is increased at a heating rate of 2 - 4°C/min, and then the casting molds are cooled naturally to room temperature. By controlling the cooling rate at the aging treatment stage, it is possible to significantly reduce the occurrence of defects, which contributes to increasing the plasticity, as well as maintaining high mechanical strength of the products. The embodiments of the preparation method according to the present invention are described in detail below.

Implementation option 1

Aluminum alloy: aluminum-silicon-magnesium alloy (A356) (purchased from: Shandong Weiqiao Aluminum Industry Co., Ltd.)

High purity aluminum ingot (purchased from: Chinalco, composition: Al (99.99%), Fe<0.1%, impurities <0.05%)

Flux:

Composition: 15 parts potassium chloride, 20 parts sodium chloride, 10 parts CaF2, 20 parts Na2CO3, 10 parts Na2SO4, 15 parts Na3AlF6, 10 parts C2Cl6.

Slag remover:

Composition: 25 parts sodium chloride, 25 parts potassium chloride, 5 parts sodium carbonate, 5 parts sodium sulfate, 5 parts sodium fluoroaluminate, 10 parts sodium fluorosilicate, 10 parts calcium fluoride, 5 parts potassium nitrate, 10 parts potassium fluorosilicate.

1) Preparation of aluminum melt

Melting: Preheated A356 aluminum-silicon-magnesium alloy is added to the preheated melting furnace, and then heated and melted within 760 degrees into aluminum melt.

Deaeration and slag removal: flux (0.3 wt.% flux) obtained by purging with nitrogen (or argon) is added to the aluminum melt after smelting, and the aeration time is controlled for 15 minutes.

Standing: The aluminum melt obtained in step S3 is stood for 10 minutes, and then, at a temperature controlled within 760 degrees, slags and impurities are removed from the surface of the aluminum melt.

During this period, samples of the aluminum melt are taken after standing to determine the chemical composition and assess the hydrogen content:

Determination of the hydrogen content in the aluminum melt after standing is carried out by densimetry, requirements for density: density greater than or equal to 2.65 g/ ^cm3 . The higher the density (closer to 2.7 g/ ^cm3 ), the lower the hydrogen content in the melt.

2) Cleaning the ligature

2.1) Aluminum-strontium ligature: purchased from Nantong Angshen Metal Materials Co., Ltd., composition: Al-10Sr, Fe<0.05.

Pre-treatment: cleaning the surface of the aluminum-strontium ligature from scale using a grinding machine.

Ultrasonic cleaning: The pre-treated aluminum-strontium alloy is placed in an ultrasonic cleaning tank.

Drying: The purified aluminum-strontium ligature is placed in an oven and dried at a temperature of 60 - 100°C for 30 - 60 minutes.

Melting: the aluminum-strontium ligature is placed in a preheated melting crucible at a temperature of 760 - 780°C.

Refining: is carried out after smelting the aluminum-strontium ligature. Refining of molten high-purity aluminum is carried out using a stirrer with Ar+ graphite for automatic deaeration. Refining using argon blowing is carried out at a temperature of 730 - 750 ° C for 5 - 10 minutes, the volume of flux obtained by blowing is 0.1 - 0.3% of the melt, and the holding time is 3 - 5 minutes. During the refining process, no bubbling bubbles should be observed on the surface of the aluminum melt.

Removing slag from the surface: 0.1 - 0.3% slag remover is added to the melt, and then left for 15 - 20 minutes to remove the slag formed on the surface.

Standing: carried out after slag removal for 8 - 15 minutes at a temperature of 740 - 760°C.

2.2) Refining agent: refining aluminum-titanium-boron ligature

Aluminum-titanium-boron master alloy: purchased from Nantong Angshen Metal Materials Co., Ltd. (composition and content: Ti: 5%, B: 1%, the remainder: Al)

The above-mentioned processing method is used to process the aluminum-titanium-boron ligature used as a refining agent.

3) Preparation of composite rare earth aluminum alloy

3.1) Smelting of high-purity aluminum-rare earth metal ligature

a) Preparation of high-purity aluminum melt

Pre-treatment: cleaning the surface of high-purity aluminum ingots from scale using a grinding machine.

Ultrasonic Cleaning: Pre-treated high purity aluminum ingots are placed in an ultrasonic cleaner.

Drying: After ultrasonic cleaning, high-purity aluminum ingots are placed in an oven and dried at a temperature of 60 - 100°C for 30 - 60 minutes.

Melting: Highly pure aluminum after drying is placed in a preheated crucible for melting at a temperature of 760 - 800 °C.

Refining: carried out after smelting high-purity aluminum. Specific method: refining of molten high-purity aluminum is carried out by means of a stirrer with Ar+ graphite for automatic deaeration. Refining by blowing Ar is carried out at a temperature of 740 - 760 ° C for 5 - 10 minutes, the amount of the added refining agent is 0.1 - 0.3% of the melt, and the holding time is 3 - 5 minutes. Then 0.1 - 0.3% of slag remover is added to the melt, and then it is left to stand for 10 - 20 minutes to remove the slag formed on the surface.

Standing: carried out after slag removal for 8 - 15 minutes at a temperature of 740 - 760°C.

b) Smelting of rare earth aluminum alloy:

after adjusting the temperature of the high-purity aluminum obtained in the above-mentioned item a) to 780 - 820°C, and heating and completely melting, add a rare earth aluminum-lanthanum alloy in accordance with a specified mass fraction, that is, the lanthanum content in the rare earth aluminum alloy is 0.2 ± 0.02 wt.%. (purchased from Baotou Rare Earth Research Institute, composition: Al-10La, Fe <0.05). The melt is heated under the protection of an argon atmosphere at a temperature of 780 - 820°C until completely melted.

Mixing and holding: after melting, the melt is mixed for 3-5 minutes until a homogeneous state is obtained and held for 10-20 minutes at a temperature of 760-780°C.

Refining: carried out after melting the rare earth aluminum-lanthanum alloy under the protection of argon atmosphere. Melt refining is carried out by means of a stirrer with Ar+ graphite for automatic deaeration. Refining by Ar blowing is carried out at a temperature of 760 - 780 ° C for 5 - 10 minutes, the volume of flux obtained by blowing is 0.1 - 0.3% of the melt, and the holding time is 3 - 5 minutes. During the refining process, no bubbling bubbles should be observed on the surface of the aluminum melt. Removal of slag from the melt surface: 0.1 - 0.3% of slag remover is added to the melt, and then held for 15 - 20 minutes to remove slag formed on the surface.

Standing: carried out after slag removal for 10 - 15 minutes at a temperature of 720 - 730°C.

3.2) Preparation of composite rare earth alloy

The preparation of aluminum melt, rare earth aluminum alloy, aluminum-strontium ligature and aluminum-titanium-boron ligature is carried out sequentially in accordance with the above method, then the contents are mixed and melted to obtain a composite rare earth alloy.

In this embodiment, according to the addition sequence, the rare earth aluminum alloy is first added to the aluminum melt, then the aluminum-strontium ligature, and finally the aluminum-titanium-boron ligature. The specific preparation method is:

Stage 1 - dosing: preheating high-purity aluminum, aluminum-titanium-boron ligature, aluminum-strontium ligature and rare earth aluminum alloy obtained by the above method, in accordance with the required mass fraction.

Based on the total mass of 100 parts, the content of high-purity aluminum: 4.8 parts, the content of aluminum-titanium-boron ligature: 0.2 parts, the content of aluminum-strontium ligature: 60 parts, the content of rare earth aluminum alloy: 35 parts.

Step 2 - adding and melting rare earth aluminum alloy: to prepare the above-mentioned aluminum melt, first the above-mentioned purified rare earth aluminum alloy is heated to a temperature of 780 - 820°C in order to soften it before melting, then the overall temperature of the aluminum melt is controlled within 760 - 780°C, and then after adding the rare earth aluminum alloy to the aluminum melt, it is maintained.

Throughout the entire process, the melting of rare earth aluminum alloy is carried out under the protection of an argon atmosphere.

Step 3 - After the rare earth aluminum alloy has completely melted, the temperature is controlled within 750 - 770°C and the contents are stirred for 5 - 10 minutes.

The entire process takes place under the protection of an argon atmosphere, and the stirrer with graphite materials is heated to 400 - 500°C before mixing.

In other words, after the rare earth aluminum alloy has completely melted, the temperature must be reduced slightly to prevent subsequent grain coarsening caused by overheating.

Stage 4 - after melting the melt at a temperature of 740 - 760°C, the holding time is controlled for 5 - 20 minutes. At this stage, the alloying reaction occurs.

Stage 5 - refining: after holding, refining, deaeration and slag removal are carried out. 0.3% flux is added to the melt by blowing with argon, and the aeration time is controlled for 3 - 8 minutes; then 0.2% slag remover is added to the melt, and then after mixing for 5 minutes, it is held to remove slag and impurities from the surface of the melt. The entire process takes place under the protection of an argon atmosphere.

Before and during refining, samples of the aluminum melt are taken to measure the density of the melt and determine the hydrogen content. Density metry is used as the measurement method (compared to the theoretical value of the density of aluminum of 2.70 g / cm ³ ). If the measured density of the sample is close to 2.7 g / cm ³ , this indicates a low hydrogen content in aluminum. As a rule, the density of the sample does not reach 2.7 g / cm ³ ; if the density of the sample during the test is approximately 2.65 g / cm ³ , then vacuum treatment is required to determine the hydrogen content. If the hydrogen content does not meet the requirements, it is necessary to continue refining, i.e. re-add flux and slag remover.

Stage 6 - standing: the melt after adding rare earth aluminum alloy and refining is stood for 3-5 minutes, and the temperature is controlled within 740-760°C.

Step 7 - adding and melting aluminum-strontium ligature: the above aluminum-strontium ligature is added to the melt obtained in step 6 after refining, and the temperature is controlled within 780 - 820 °C to achieve complete melting of the aluminum-strontium ligature. Throughout the process, the melting of the aluminum-strontium ligature is carried out under the protection of an argon atmosphere.

Stage 8 - after the aluminum-strontium ligature has completely melted, the temperature is controlled within 740 - 760°C, and the contents are stirred for 3 - 8 minutes until a homogeneous state is obtained. The entire process takes place under the protection of an argon atmosphere, and the stirrer with graphite materials is heated to 400 - 500°C before stirring.

Stage 9 - then holding at a temperature of 725 - 750°C. The holding time is controlled for 15 - 30 minutes.

Step 10 - refining, deaeration and slag removal: after holding the melt, 0.3% flux is added to the composite rare earth aluminum melt by argon blowing, and the aeration time is controlled for 5 - 10 minutes; then 0.2% slag remover is added to the aluminum melt, and then stirred for 5 minutes to remove slag and impurities on the surface of the composite rare earth aluminum melt. The whole process is carried out under the protection of argon atmosphere.

Before and during refining, aluminum melt samples are taken to determine the hydrogen content. (Hydrogen content requirements: greater than or equal to 2.65 g/cm ³ ). Vacuum treatment is required during the hydrogen measurement process. If the hydrogen content does not meet the requirements, it is necessary to continue refining, that is, re-add flux and slag remover.

Step 11 - adding aluminum-titanium-boron ligature: aluminum-titanium-boron ligature is added to the above-treated melt obtained in step 10, then heated until completely melted and stirred for 3 - 5 minutes until a homogeneous state is obtained.

Step 12 – holding: after mixing, the melt is held for 8–12 minutes, and the temperature is controlled within the range of 715–725°C.

Step 13 - refining, deaeration and slag removal: after holding the melt, 0.3% flux is added to the composite rare earth aluminum melt by argon blowing, and the aeration time is controlled for 5 - 10 minutes; then 0.2% slag remover is added to the aluminum melt, and then stirred for 5 minutes to remove slag and impurities on the surface of the composite rare earth aluminum melt. The whole process is carried out under the protection of argon atmosphere.

Before and during refining, samples of aluminum melt are taken to determine the hydrogen content. (Hydrogen content requirements: greater than or equal to 2.65 g/cm ³ ). During the hydrogen measurement process, vacuum treatment is required. If the hydrogen content does not meet the requirements, refining must be continued, that is, flux and slag remover must be added again.

Step 14 - Casting: Preheating the molds at a temperature of 300 - 400°C. For the casting process, the temperature of the above-mentioned rare earth composite alloy obtained in Step 13 is controlled within the range of 715 - 725°C.

It is preferable that during casting, oxides on the surface layer of the composite rare earth aluminum melt are filtered using a glass fiber filter; the filtration of the surface layer of the composite rare earth aluminum melt is carried out before each casting.

It is preferable if the water cooling method used for cooling the composite rare earth aluminum alloy cast in the molds is used for cooling the molds. In the cooling process, the solidification rate of the aluminum melt is controlled within the range of 50 - 100 °C/s, and sequential solidification is used as the solidification method.

It should be noted that the ratio of the components of the composite rare earth aluminum alloy is not limited to the above embodiments, for example, the calculated mass ratio of rare earth metal: strontium: titanium or titanium-boron is 1: (0.1 - 1.2): (0.1 - 1.2).

4) Preparation of casting molds from modified aluminum alloy

The aluminum-silicon-magnesium alloy, the composite rare earth aluminum alloy and the aluminum-titanium-boron ligature are prepared in accordance with the mass ratio of the aluminum alloy: composite rare earth aluminum alloy: aluminum-titanium-boron ligature equal to 99.4:0.4:0.2.

Next, smelting is carried out in accordance with the following stages:

mixing: when the temperature is controlled within 740±5°C, the composite rare earth aluminum alloy obtained as specified in 3) is added to the above processed aluminum-silicon-magnesium alloy according to the above ratio specified in 1).

stirring: the added composite rare earth aluminum alloy and the melt after melting are stirred using a stirrer with graphite materials, during the stirring process, it is necessary to comply with the requirements for uniform mixing, sequential stirring is carried out for 8 minutes;

holding: after mixing, the holding temperature is controlled within 735°C, and the holding time is 20 minutes;

refining: after holding, a slag remover is added to the aluminum melt by blowing with argon, and the deaeration time is controlled within 15 minutes;

adding a refining agent: 0.2% aluminum-titanium-boron ligature is added to the melt with flux, and then, after complete melting and mixing, refining is continued.

holding and standing: after refining, the aluminum melt enters the holding tank, and when the temperature is within 710 ± 3°C, slag and impurities are removed from the surface of the aluminum melt after standing for 10 ± 2 minutes;

Casting: After preheating the molds to 250 - 400°C, the above-mentioned modified aluminum alloy after refining is cast into the molds at a temperature controlled within 700 ± 5, then the molds are cooled to obtain modified aluminum alloy casting molds. Among them, the thickness of the casting molds of this modified aluminum alloy is 30mm.

5) Heat treatment

Solution etching treatment: The casting molds made of the above modified aluminum alloy are placed in a heating furnace to heat up to 540°C at a rate of 2°C/min, and then held for 120 min.

Water quenching treatment: The modified aluminum alloy casting molds after solution treatment are added to a water bath at 65°C, and then water quenched for 3 min.

Aging treatment: the modified aluminum alloy casting molds are placed in an incubator at 120°C after water quenching treatment and held for 120 min. Then the incubator temperature is increased to 160°C at a heating rate of 2°C/min and the casting molds are held for 30 min. After that, the casting molds are cooled naturally to room temperature to obtain products made of highly plastic composite material based on the modified aluminum alloy.

Fig. 1 shows images of the metallographic structure of aluminum alloy products at different stages, among them, (a) is an image of the A356 aluminum alloy before heat treatment, (b) is an image of the A356 aluminum alloy after heat treatment, (c) is an image of the aluminum alloy after modification of composite materials and before heat treatment indicated in embodiment 1, (d) is an image of the aluminum alloy after modification of composite materials and heat treatment indicated in embodiment 1. From Fig. 1 it is seen that the metallographic structure of the modified and heat-treated aluminum alloy in this embodiment is further increased compared to the α-Al phase in the form of a relatively round ball, and the primary α-Al phase and dendrites are practically not visible. In other words, additional homogenization of the grains is carried out so that their microstructure becomes more uniform. In addition, the α-Al phase in the form of a ball is uniformly distributed along the grain boundaries. The metallographic structure of the heat-treated aluminum alloy (i.e., image (c)) is further enlarged compared to the α-Al phase in the form of a relatively round ball, and the primary α-Al phase and dendrites are almost invisible. In other words, additional homogenization of the grains is carried out so that their microstructure becomes more uniform.

In addition, the mechanical properties of the aluminum alloy A356 (designated as: before modification), the casting molds after modification (designated as: modified alloy 1), and the product after heat treatment (designated as: embodiment 1) were evaluated. The evaluation results are presented in Table 1 below.

Table 1. Results of evaluation of mechanical properties of products made of highly plastic composite material based on modified aluminum alloy, described in embodiment 1 Mechanical properties Before modification Modified alloy 1 Implementation option 1 Tensile strength (MPa) 130±3.5 220±5 280±6 Yield strength (MPa) 65±5.5 108±6 200±5 Elongation coefficient (%) 3±0.25 20±0.6 16±0.5

It can be seen from Table 1 that, through the heat treatment described in Embodiment 1 and even without heat treatment, the plasticity of the products can be significantly improved. Based on the comprehensive heat treatment, the yield strength and tensile strength are significantly improved (compared with aluminum alloy ingots that have not undergone modification and heat treatment, the yield strength and tensile strength increase by almost 3 times or more than 2 times), and the high elongation coefficient is also maintained (compared with untreated aluminum alloy ingots, the elongation coefficient increases by more than 5 times), which significantly improves the comprehensive mechanical properties.

Implementation option 2

In this embodiment, compared with the above-mentioned embodiment 1, a combination of a rare earth aluminum alloy, an aluminum-strontium master alloy, an aluminum-titanium master alloy, or an aluminum-titanium-boron master alloy is used as a modifier, the other points are the same as those in embodiment 1.

Only the components used in the processing of modified aluminum alloy are described below:

4) Preparation of casting molds from modified aluminum alloy

The preparation of the above-mentioned aluminum-silicon-magnesium alloy, rare-earth aluminum alloy, aluminum-strontium ligature, and aluminum-titanium-boron ligature is carried out in accordance with the mass ratio of aluminum alloy: rare-earth aluminum alloy (the method for purifying the rare-earth aluminum alloy is similar to the method specified in embodiment 1): aluminum-strontium ligature: aluminum-titanium-boron ligature, equal to 99.4:0.2:0.2:0.2.

Next, melting is carried out in accordance with the following stages:

mixing: when the temperature is controlled within 740 ± 5°C, the composite rare earth aluminum alloy is added to the above processed aluminum-silicon-magnesium alloy in accordance with the above ratio of 1);

stirring: the added rare earth aluminum alloy and the melt after smelting are stirred using a stirrer with graphite materials, during the stirring process, it is necessary to comply with the requirements for uniform mixing, sequential stirring is carried out for 8 minutes;

holding: after mixing, the holding temperature is controlled within 735°C, and the time is controlled within 20 minutes;

refining: after holding, a slag remover is added to the aluminum melt by blowing with argon, and the deaeration time is controlled within 15 minutes;

adding aluminum-strontium ligature: 0.2% aluminum-strontium ligature is added to the melt with flux, then after complete melting and mixing, refining is continued;

homogenization: after the aluminum-strontium ligature has completely melted, the temperature is controlled within 740 - 760°C, and the contents are stirred for 3 - 8 minutes until a homogeneous state is obtained;

aging: then the contents are maintained at a temperature of 725 - 750°C, and the time is controlled for 15 - 30 minutes;

adding a refining agent: 0.2% aluminum-titanium-boron ligature is added to the melt with flux, and then, after complete melting and mixing, refining is continued;

holding and standing: after refining, the aluminum melt enters the holding tank, and when the temperature is within 710 ± 3°C, slag and impurities are removed from the surface of the aluminum melt after standing for 10 ± 2 minutes;

casting: after preheating the molds to 250 - 400°C, the above-mentioned modified aluminum alloy is cast into the molds after refining at a temperature controlled within 700 ± 5, then the molds are cooled to obtain casting molds made of modified aluminum alloy;

the image of the metallographic structure of the products obtained in this embodiment is similar to the image indicated in embodiment 1, therefore this information will be omitted.

Table 2. Results of evaluation of mechanical properties of products made of highly plastic composite material based on modified aluminum alloy, described in embodiment 2 Mechanical properties Before modification Modified alloy 2 Implementation option 2 Tensile strength (MPa) 130±3.5 200±5.5 240±3.5 Yield strength (MPa) 65±5.5 95±4.2 180±3.8 Elongation coefficient (%) 3±0.25 16.6±0.35 14.2±0.35

Among them, modified alloy 2 indicates casting molds after modification that were not subjected to heat treatment.

From Table 2 it can be seen that by means of the heat treatment described in this embodiment 2 it is also possible to obtain results similar to the results of the above embodiment 1.

In addition, it can also be noted that, compared with embodiment 2, the rare earth aluminum alloy and the aluminum-strontium ligature are first melted to obtain a composite rare earth aluminum alloy, and the composite modified aluminum alloy products (that is, the products of embodiment 1) obtained by modifying the composite rare earth aluminum alloy have higher comprehensive mechanical properties.

Implementation option 3

In this embodiment, compared with the above embodiment 1, ZL111 is used instead of A356, and the other stages are the same.

The specific preparation method is indicated in embodiment 1, therefore this information will be omitted.

In addition, the mechanical properties of the ZL111 aluminum alloy (designated as: before modification), the casting molds after modification (designated as: modified alloy 3), and the product after heat treatment (designated as: embodiment 3) were evaluated. The evaluation results are shown in Table 3 below.

Table 3. Results of evaluation of mechanical properties of products made of highly plastic composite material based on modified aluminum alloy described in embodiment 3 Mechanical properties Before modification Modified alloy 3 Implementation option 3 Tensile strength (MPa) 160±4.5 240±5 330±6 Yield strength (MPa) 75±4.5 120±5 220±4.5 Elongation coefficient (%) 3±0.25 15±0.5 12±0.5

It can be seen from Table 3 that, by means of the heat treatment described in this embodiment 3, it is also possible to obtain results similar to those of the above embodiments 1 and 2. In other words, the preparation method of the present invention is also applicable to a eutectic aluminum alloy, by means of which it is possible to obtain higher strength and higher impact toughness of the products.

The above description represents preferred embodiments of the present invention. It should be noted that those skilled in the art can make some changes without departing from the essence of the present invention, and these changes will fall within the scope of protection of the present invention.

Claims (27)

1. A method for producing products from a modified aluminum alloy, characterized in that it consists of the following stages: stage S1 – preparation of molten aluminum alloy; stage S2 – preparation of the modifier; wherein the above-mentioned modifier is a combination of an aluminum alloy containing a rare earth metal and an aluminum-titanium ligature or of an aluminum alloy containing a rare earth metal and an aluminum-titanium-boron ligature, wherein the aluminum alloy containing a rare earth metal also contains strontium, titanium, or titanium and boron, wherein the mass ratio of the total amount of the above-mentioned rare earth metal: strontium: titanium or titanium and boron is 1: (0.1-1.2): (0.1-1.2), the rare earth metal in the above-mentioned aluminum alloy containing a rare earth metal is one or more metals such as lanthanum, cerium and yttrium, wherein the method for preparing the above-mentioned aluminum alloy containing a rare earth metal includes: stage S211 – preparation of the above-mentioned aluminum melt; step S212 – preparing an aluminum-strontium ligature, an aluminum-titanium or aluminum-titanium-boron ligature and a rare earth metal-aluminum ligature, wherein the rare earth metal in the aforementioned rare earth metal-aluminum ligature is one or more elements such as lanthanum, cerium and yttrium; step S213 – in an inert gas atmosphere, the above-mentioned rare earth metal-aluminum ligature, aluminum-strontium ligature, aluminum-titanium ligature or aluminum-titanium-boron ligature are successively added to the above-mentioned aluminum melt for smelting to obtain the above-mentioned aluminum alloy containing a rare earth metal; stage S3 – in an inert gas atmosphere, a smelting modifier is added to the above-mentioned aluminum alloy melt to obtain a modified aluminum alloy melt, wherein the amount of the above-mentioned modifier is 0.4-0.6 wt.% of the total amount of the modified aluminum alloy melt; step S4 – casting is performed using the above-mentioned modified aluminum alloy to obtain blanks made of modified aluminum alloy; stage S5 – heat treatment of the modified aluminum alloy blanks is carried out, wherein the above-mentioned heat treatment process includes: solid solution processing, in which workpieces made of modified aluminum alloy are heated to 530-550°C and held for 120-300 minutes; water quenching treatment, in which the modified aluminum alloy blanks, after solution treatment, are placed in a water bath at a temperature of 60–70°C and quenched for 2–4 minutes; and aging treatment, in which blanks made of modified aluminum alloy are held at a temperature of 110-140°C for 120-240 min, then the temperature is increased to 160-200°C and the blanks are held for 20-60 min, with the temperature from 110-140°C to 160-200°C being increased at a heating rate of 2-4°C/min, After this, the blanks are cooled to room temperature to obtain products made of modified aluminum alloy. 2. The method according to claim 1, characterized in that the above-mentioned step S1 includes: ensuring the availability of aluminum alloy castings; removing scale from the surface of castings made of the above-mentioned aluminum alloy, cleaning and drying; melting aluminum alloy castings after drying, refining, removing slag to obtain the above-mentioned aluminum alloy melt; wherein the composition of the castings from the above-mentioned aluminum alloy is a hypoeutectic aluminum alloy or a eutectic aluminum alloy. 3. The method according to claim 1, characterized in that the above-mentioned step S3 includes: step S310 - adding said aluminum alloy containing a rare earth metal to said aluminum alloy melt to obtain a homogeneous melt; and step S320 – adding the above-mentioned aluminum-titanium or aluminum-titanium-boron ligature to the above-mentioned homogeneous melt obtained in step S310, and continuing the melting to obtain the above-mentioned modified aluminum alloy. 4. The method according to item 1, characterized in that at stage S5 the heating rate during solid solution processing is regulated in the range of 1.5-3°C/min, and the holding time is 120-180 min. 5. The method according to claim 1, characterized in that the above-mentioned solid solution treatment, water quenching treatment and aging treatment are continuous processes, and the above-mentioned water bath is a circulating water bath, and after the water quenching treatment and before the aging treatment, the temperature of the modified aluminum alloy workpieces is maintained above 55°C. 6. A product made of a modified aluminum alloy, characterized in that it is obtained by the method according to any of paragraphs. 1-5 and has a tensile strength of 280 MPa or higher, a yield strength of 200 MPa or higher, and an elongation coefficient of 12% or higher.