High-toughness high-thermal-conductivity die-casting aluminum alloy, preparation method thereof and structural part

Abstract

The invention provides a high-toughness high-thermal-conductivity die-casting aluminum alloy, a preparation method thereof and a structural part. The method comprises the following steps: adding industrial silicon and steel scrap into a secondary aluminum melt to obtain a mixed melt; boronizing treatment and refining treatment are carried out; magnesium alloy waste, Sr, RE, Cr, Zn and Al-Ti-B alloy are added into the mixed melt, refining treatment and die casting treatment are conducted, and then the aluminum alloy is obtained. The invention relates to a high-strength aluminum alloy, which comprises the following components in percentage by mass: 6 to 11 percent of Si, 0.05 to 0.8 percent of Fe, 0.2 to 3 percent of Mg, 0.001 to 0.1 percent of Sr, 0 to 0.2 percent of RE, 0 to 0.3 percent of Ti, 0 to 0.05 percent of B, 0 to 1 percent of Zn and 0.0001 to 0.5 percent of Cr.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and in particular to a high-toughness and high-thermal-conductivity die-cast aluminum alloy, a preparation method thereof, and a structural part. Background Art

[0002] Recycled aluminum, steel scrap, and magnesium alloy scrap are cheap, but they contain many types of impurities and high content. Reducing the impurity content in recycled aluminum, steel scrap, and magnesium alloy scrap to a lower level will greatly increase the cost, which results in lower elongation and thermal conductivity of aluminum alloys prepared with recycled aluminum, steel scrap, and magnesium alloy scrap as raw materials.

[0003] Therefore, there is an urgent need for a method for preparing high-toughness and high-thermal-conductivity aluminum alloy by reusing recycled aluminum, steel waste, and magnesium alloy waste. Summary of the invention

[0004] In view of the above-mentioned defects of the prior art, the present invention provides a method for preparing a high-toughness and high-thermal-conductivity die-cast aluminum alloy, aiming to recycle recycled aluminum, steel waste, and magnesium alloy waste to produce a high-toughness and high-thermal-conductivity die-cast aluminum alloy with excellent elongation and thermal conductivity.

[0005] The present invention provides a method for preparing a high-toughness and high-thermal-conductivity die-cast aluminum alloy, comprising the following steps: Heating the recycled aluminum to obtain a recycled aluminum melt; The temperature is adjusted to 740-860° C., and industrial silicon and steel waste are added to the recycled aluminum melt to obtain a mixed melt; performing a boronization treatment and a first refining treatment on the mixed melt; The temperature is adjusted to 710-780° C., magnesium alloy scrap, Sr, RE, Cr, Zn, and Al-Ti-B alloy are added to the mixed melt after the first refining treatment, the mixed melt is subjected to a second refining treatment, and the components and contents in the mixed melt after the second refining treatment are measured; and When the components and contents in the mixed melt after the second refining treatment meet the standards, the mixed melt is die-casted to obtain a high-toughness and high-thermal-conductivity die-cast aluminum alloy, wherein the high-toughness and high-thermal-conductivity die-cast aluminum alloy contains 6-11% Si by mass, 0.05-0.8% Fe by mass, 0.2-3% Mg by mass, 0.001-0.1% Sr by mass, 0-0.2% RE by mass, 0-0.3% Ti by mass, 0-0.05% B by mass, 0-1% Zn by mass, and 0.0001-0.5% Cr by mass.

[0006] Furthermore, the high toughness and high thermal conductivity die-cast aluminum alloy contains 6-11% Si by mass, 0.2-0.8% Fe by mass, 1-3% Mg by mass, 0.001-0.1% Sr by mass, 0.01-0.1% RE by mass, 0.001-0.1% Ti by mass, 0.001-0.05% B by mass, 0.1-0.5% Zn by mass, and 0.001-0.2% Cr by mass.

[0007] Furthermore, the sum of the mass percentage contents of Sr, RE, B, and Cr is less than the mass percentage content of Fe.

[0008] Furthermore, the ratio of the sum of the mass percentage contents of Sr, RE, B, and Cr to the mass percentage content of Fe is 0.01-0.6:1.

[0009] Furthermore, the preparation method of the high-toughness and high-thermal-conductivity die-cast aluminum alloy also includes the step of adding at least one of Cu, V, Ca, Zr, Te, Ag, Sb, Bi, Nb, SiC, AlTiC, and BN to the recycled aluminum melt, wherein the mass percentage content of Cu is 0.0001-1%, the mass percentage content of V is 0.005-0.2%, the mass percentage content of Ca is 0.0001-0.3%, the mass percentage content of Zr is 0.0001-0.5%, the mass percentage content of Te is 0-0.2%, the mass percentage content of Ag is 0-0.2%, the mass percentage content of Sb is 0-0.5%, the mass percentage content of Bi is 0-0.2%, the mass percentage content of Nb is 0-0.3%, the mass percentage content of SiC is 0-1%, the mass percentage content of TiC is 0-1%, and the mass percentage content of BN is 0-0.5%.

[0010] Furthermore, at least one of the following conditions is met: The boronizing agent for the boronizing treatment is potassium fluoroborate and / or aluminum boron alloy; The mass ratio of the boronizing agent to the mixed melt in the boronizing treatment is 0.001-0.005:1; The temperature of the first refining treatment is 740-800°C and the time is 20-60min; The refining agent of the first refining treatment is at least one of chloride salt, fluoride salt, and rare earth; The mass ratio of the refining agent to the mixed melt in the first refining treatment is 0.0001-0.0005:1; The temperature of the second refining treatment is 690-750°C and the time is 10-40min; The refining agent of the second refining treatment includes at least one of chloride salt, fluoride salt, and rare earth; The mass ratio of the refining agent to the mixed melt in the second refining treatment is 0.001-0.2:1.

[0011] Furthermore, after the mixed melt is subjected to die-casting to obtain an aluminum alloy part, the method for preparing a high-toughness and high-thermal-conductivity die-cast aluminum alloy further comprises the step of performing an aging treatment on the aluminum alloy part, wherein: The aging treatment is performed at a temperature of 150-250°C and a time of 0.05-30h; or The aging treatment includes a primary low-temperature electric field aging treatment and a secondary high-temperature aging treatment, wherein the temperature of the primary low-temperature electric field aging treatment is 50-120°C, the time is 0.1-100h, and the electric field strength is 2-50kV / cm; the temperature of the secondary high-temperature aging treatment is 140-250°C, and the time is 0.1-50h.

[0012] The present invention also provides a high-toughness and high-thermal-conductivity die-cast aluminum alloy, which contains Al, and also contains Si with a mass percentage content of 6-11%, Fe with a mass percentage content of 0.05-0.8%, Mg with a mass percentage content of 0.2-3%, Sr with a mass percentage content of 0.001-0.1%, RE with a mass percentage content of 0-0.2%, Ti with a mass percentage content of 0-0.3%, B with a mass percentage content of 0-0.05%, Zn with a mass percentage content of 0-1%, and Cr with a mass percentage content of 0.0001-0.5%.

[0013] Furthermore, the high-toughness and high-thermal-conductivity die-cast aluminum alloy also contains at least one of Cu, V, Ca, Zr, Te, Ag, Sb, Bi, Nb, SiC, AlTiC, and BN, wherein the mass percentage content of Cu is 0.0001-1%, the mass percentage content of V is 0.005-0.2%, the mass percentage content of Ca is 0.0001-0.3%, the mass percentage content of Zr is 0.0001-0.5%, the mass percentage content of Te is 0-0.2%, the mass percentage content of Ag is 0-0.2%, the mass percentage content of Sb is 0-0.5%, the mass percentage content of Bi is 0-0.2%, the mass percentage content of Nb is 0-0.3%, the mass percentage content of SiC is 0-1%, the mass percentage content of TiC is 0-1%, and the mass percentage content of BN is 0-0.5%.

[0014] The present invention also provides a structural part, the material of the structural part is the high-toughness and high-thermal conductivity die-cast aluminum alloy prepared by the preparation method of the high-toughness and high-thermal conductivity die-cast aluminum alloy, or the high-toughness and high-thermal conductivity die-cast aluminum alloy.

[0015] In the technical solution of the present invention, industrial silicon, steel waste and magnesium alloy waste are used as the main raw materials, which can greatly reduce the cost; and Sr, RE, Ti, B, Zn, and Cr alloy elements are added, combined with multiple refining treatments and boronization treatments, a high-toughness and high-thermal-conductivity die-cast aluminum alloy with excellent comprehensive performance can be obtained. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] The present invention provides a method for preparing a high-toughness and high-thermal-conductivity die-cast aluminum alloy, comprising the following steps: Heating the recycled aluminum to obtain a recycled aluminum melt; The temperature is adjusted to a high temperature, about 740-860° C., and industrial silicon and steel waste are added to the recycled aluminum melt to obtain a mixed melt; performing a boronization treatment and a first refining treatment on the mixed melt; The temperature is adjusted to 710-780° C., and after adding magnesium alloy scrap, Sr, RE, Cr, Zn, and Al-Ti-B alloy to the mixed melt after the first refining treatment, the mixed melt is subjected to a second refining treatment, a slag removal treatment, a degassing treatment, and a standing treatment, and the surface scum is scraped off after the standing treatment; and The components and contents of the mixed melt after the static treatment are measured. When the components and contents of the mixed melt after the static treatment meet the standards, the mixed melt after the static treatment is subjected to die casting to obtain a high-toughness and high-thermal-conductivity die-cast aluminum alloy. The high-toughness and high-thermal-conductivity die-cast aluminum alloy contains 6-11% Si by mass, 0.05-0.8% Fe by mass, 0.2-3% Mg by mass, 0.001-0.1% Sr by mass, 0-0.2% RE by mass, 0-0.3% Ti by mass, 0-0.05% B by mass, 0-1% Zn by mass, and 0.0001-0.5% Cr by mass.

[0018] In one embodiment, the high toughness and high thermal conductivity die-cast aluminum alloy contains 6-11% Si by mass, 0.2-0.8% Fe by mass, 1-3% Mg by mass, 0.001-0.1% Sr by mass, 0.01-0.1% RE by mass, 0.001-0.1% Ti by mass, 0.001-0.05% B by mass, 0.1-0.5% Zn by mass, and 0.001-0.2% Cr by mass.

[0019] The mass percentage content of Si may be 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, or 11%.

[0020] The mass percentage content of Fe may be 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, or 0.8%.

[0021] The mass percentage content of Mg may be 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.45%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.78%, 0.85%, 0.9%, 0.95%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, or 3%.

[0022] The mass percentage content of Sr may be 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, or 0.1%.

[0023] The mass percentage content of RE may be 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, or 0.2%. RE may be at least one of La, Ce, Pr, Nd, Er, Sm, Y, Sc, and Gd.

[0024] The mass percentage content of Ti may be 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, or 0.3%.

[0025] The mass percentage content of Zn may be 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, or 1%.

[0026] The mass percentage content of Cr can be 0.0001%, 0.0005%, 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.3%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, 0.4%, 0.41%, 0.42%, 0.43%, 0.44%, 0.45%, 0.46%, 0.47%, 0.48%, 0.49%, or 0.5%.

[0027] The sum of the mass percentage contents of Sr, RE, B, and Cr is less than the mass percentage content of Fe. The ratio of the sum of the mass percentage contents of Sr, RE, B, and Cr to the mass percentage content of Fe is 0.01-0.6:1 to ensure that the Fe morphology is effectively regulated. The ratio of the sum of the mass percentage contents of Sr, RE, B, and Cr to the mass percentage content of Fe can be specifically 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, or 0.6:1.

[0028] The mass ratio of the recycled aluminum, industrial silicon, steel waste, and magnesium alloy waste is 85.2-93.75:6-11:0.05-0.8:0.2-3. When adding industrial silicon, steel waste, and magnesium alloy waste to the recycled aluminum melt, the burnout rate of industrial silicon, steel waste, and magnesium alloy waste must be considered to ensure that the components and contents of the mixed melt after refining meet the standards. The components and contents of the mixed melt can be analyzed by spectroscopy. When the components and contents in the mixed melt do not meet the standards, the corresponding content of elements can be added or a second refining treatment and slag removal treatment can be performed again until the standards are met. Furthermore, the standards of the components and contents in the mixed melt after the second refining treatment are: 6-11% Si by mass, 0.05-0.8% Fe by mass, 0.2-3% Mg by mass, 0.001-0.1% Sr by mass, 0-0.2% RE by mass, 0-0.3% Ti by mass, 0-0.05% B by mass, 0-1% Zn by mass, and 0.0001-0.5% Cr by mass.

[0029] When the content of impurity elements in the mixed melt is too high and does not meet the standard, the content of the impurities can be diluted by adding pure Al ingots to the mixed melt to make the content lower than the standard.

[0030] When the mixed melt is cooled to 680-700°C, the mixed melt is subjected to die casting. The die temperature of the die casting process can be 220-300°C, and the die casting speed can be 0.23-2.5m / s. The die used in the die casting process includes a movable die and a fixed die, and both the movable die and the fixed die are formed with a parting surface, and the two parting surfaces jointly form a cavity for accommodating the mixed melt, and an aluminum alloy product with a certain shape is formed. Before the die casting process, both parting surfaces can be surface treated, and the surface treatment is to form a boron carbide layer on the parting surface, and the boron carbide layer can not only improve the demoulding performance, but also improve the wear resistance of the mold, and can resist the erosion of chemical substances such as acid, alkali, and salt and the thermal erosion of aluminum alloy, to extend the service life of the mold. The thickness of the boron carbide layer can be 1-10mm, specifically 1mm, 2mm, 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, or 10mm.

[0031] The surface treatment may be: mixing a boron-containing gas (such as BCl3) and a carbon-containing gas (such as CH4) to obtain a mixed gas; introducing the mixed gas into the cavity, and using a chemical vapor deposition method, the boron-containing gas and the carbon-containing gas react chemically and are deposited on the parting surface to generate a boron carbide layer. The temperature of the chemical vapor deposition method is 900-1200°C, the deposition pressure is 200-500pa, and the carrier gas flow rate is 100-200sccm.

[0032] During the die-casting process, the boron carbide layer can make the hardness of the mold steel reach 3000-4000 Hv; the boron carbide layer can reduce the affinity of the mixed melt to the mold surface, improve the demoulding performance of the aluminum alloy, and can be demoulded smoothly even without adding Fe and Mn, which greatly improves the elongation of the aluminum alloy; the boron carbide layer can resist the erosion of chemical substances such as acids, alkalis, and salts to improve the corrosion resistance of the aluminum alloy; the boron carbide layer can still maintain good physical and chemical properties under high temperature environment, and can improve the thermal stability of the aluminum alloy; the boron carbide layer has an extremely low friction coefficient, improves the surface smoothness of the aluminum alloy, and can significantly reduce the wear and energy consumption of the aluminum alloy product caused by mechanical friction; the boron carbide layer also has a high heat transfer property. At the moment of aluminum alloy forming, the boron carbide layer can quickly conduct heat and improve the heat transfer speed of the mold. The heat transfer speed is 2-4 times that of the heat transfer speed of ordinary molds, so that the formed aluminum alloy can be cooled faster and the structure is more refined, thereby improving the strength and elongation of the aluminum alloy.

[0033] In one embodiment, the aging treatment temperature is 150-250°C, and the time is 0.05-30h. The aging treatment temperature can be 150°C, 200°C, or 250°C, and the time can be 0.05h, 1h, 5h, 10h, 15h, 20h, 25h, or 30h.

[0034] In another embodiment, the aging treatment includes a primary low-temperature electric field aging treatment and a secondary high-temperature aging treatment. The temperature of the primary low-temperature electric field aging treatment is 50-120°C, the time is 0.1-100h, and the electric field strength is 2-50kV / cm. The temperature of the primary low-temperature electric field aging treatment can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, or 120°C, and the time can be 0.1h, 0.5h, 1h, 5h, 10h, 15h, 20h, 25h, 30h, 35h, 40h, 45h, 5 The secondary high temperature aging treatment has no electric field effect, and its temperature is 140-250°C and the time is 0.1-50h. The temperature of the secondary high temperature aging treatment may be 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, or 250°C, and the time may be 0.1h, 0.5h, 1h, 5h, 10h, 15h, 20h, 25h, 30h, 35h, 40h, 45h, or 50h.

[0035] During the first-level low-temperature electric field aging treatment, the low temperature of 50-120°C can inhibit atomic segregation, while causing the alloy to produce a greater degree of supercooling, significantly increasing the range of the GP zone, facilitating the subsequent high-temperature process to increase the nucleation rate, and the alloy elements can be more fully precipitated. Secondly, since the application of an electric field at low temperature reduces the precipitation activation energy of the phase in the alloy, the low-temperature electric field aging can accelerate the precipitation nucleation rate of the precipitate phase during the aging process and increase the volume fraction of the nucleation point. The hardness of the alloy increased significantly at the beginning of the electric field aging. During the subsequent second-level high-temperature aging treatment, the time required for the alloy to reach the peak hardness was shortened, the volume fraction of the precipitate phase was increased, and the size of the precipitate phase was refined. With the increase of the electric field intensity during the first-level low-temperature electric field aging treatment, the number of strengthening phase nucleation points precipitated in the alloy increased sharply, indicating that increasing the electric field intensity can increase the nucleation precipitation rate of the precipitate phase, and has no obvious effect on the growth of the second-level high-temperature aging phase without the action of the electric field, and no size coarsening will occur.

[0036] The degassing treatment is to introduce an inert gas into the mixed melt, and the inert gas may be helium, neon, argon, krypton, or nitrogen. The degassing treatment time may be 10-15 minutes, and the gas pressure may be 0.2-0.4 MPa. The standing treatment time may be 20-30 minutes. Inert gas is introduced into the mixed melt, and the mixed melt is degassed and stood, and the gas can be separated from the mixed melt, thereby reducing the bubble content in the mixed melt, ensuring that high-quality aluminum alloy can be cast.

[0037] The boronizing agent for the boronization treatment is potassium fluoroborate and / or aluminum boron alloy. The ratio of the aluminum boron alloy is 0.001-0.005:1, specifically 0.001:1, 0.002:1, 0.003:1, 0.004:1, or 0.005:1.

[0038] In one embodiment, the boronizing agent includes 20-80 wt % of potassium fluoroborate and 20-80 wt % of aluminum boron alloy.

[0039] The temperature of the first refining treatment is 740-800°C, specifically 740°C, 750°C, 760°C, 770°C, 780°C, 790°C, or 800°C, and the time is 20-60min, specifically 20min, 30min, 40min, 50min, 60min. The refining agent of the first refining treatment can be at least one of chloride salt, fluoride salt, and rare earth. The chloride salt is at least one of sodium chloride, potassium chloride, and lithium chloride. The fluoride salt can be at least one of potassium fluoride, calcium fluoride, potassium fluoroborate, and sodium aluminum fluoride. The rare earth can be at least one of La, Ce, Pr, Nd, Er, Sm, Y, Sc, and Gd. The mass ratio of the refining agent to the mixed melt in the first refining treatment is 0.0001-0.0005:1, specifically 0.0001:1, 0.0002:1, 0.0003:1, 0.0004:1, or 0.0005:1. The first refining treatment can simultaneously perform the functions of refining and refining, thereby improving the strength and elongation of the aluminum alloy. Specifically, chloride salts and fluoride salts can play a role in improving the strength of the aluminum alloy, and rare earth can play a role in improving the elongation of the aluminum alloy. In one embodiment, the refining agent of the first refining treatment includes 10-80wt% of chloride salts, 10-80wt% of fluoride salts, and 1-20wt% of rare earth.

[0040] The temperature of the second refining treatment is 690-750°C, specifically 690°C, 700°C, 710°C, 720°C, 730°C, 740°C, or 750°C, and the time is 10-40min, specifically 10min, 20min, 30min, or 40min. The mass ratio of the refining agent to the mixed melt of the second refining treatment is 0.001-0.2:1, specifically 0.001:1, 0.005:1, 0.01:1, 0.05:1, 0.1:1, 0.15:1, or 0.2:1. The second refining treatment can simultaneously perform the functions of refining and refining, thereby improving the strength and elongation of the aluminum alloy. Specifically, chloride salts and fluoride salts can improve the strength of the aluminum alloy, and rare earth can improve the elongation of the aluminum alloy.

[0041] The refining agent of the second refining treatment may be at least one of chloride salt, fluoride salt, and rare earth. The chloride salt is at least one of sodium chloride, potassium chloride, and lithium chloride. The fluoride salt may be at least one of potassium fluoride, calcium fluoride, potassium fluoroborate, and sodium aluminum fluoride. The rare earth may be at least one of La, Ce, Pr, Nd, Er, Sm, Y, Sc, and Gd. In one embodiment, the refining agent of the first refining treatment includes 10-80wt% of chloride salt, 10-80wt% of fluoride salt, and 1-20wt% of rare earth.

[0042] Recycled aluminum is an aluminum alloy obtained by remelting waste aluminum and waste aluminum alloy materials, or remelting aluminum-containing waste materials. Recycled aluminum can include recycled cast aluminum alloy and recycled deformed aluminum alloy. The impurity content in recycled cast aluminum alloy is higher than that in recycled deformed aluminum alloy, but the price is lower. This application can use recycled cast aluminum alloy to reduce costs and obtain better performance, and can also use recycled deformed aluminum alloy.

[0043] Fe, Si, Cu, Mn, Ti, Cr, V, Mg, Zn, and Pb are impurities in recycled aluminum. In recycled cast aluminum alloy raw materials, Al≥80wt%, Fe is 1.2-4wt%, Si is 1-20wt%, Cu≤6wt%, Mn≤1wt%, Ti≤0.2wt%, Cr≤0.3wt%, V≤0.3wt%, Mg≤8wt%, Zn≤8wt%, Pb≤0.2wt%, and organic matter≤0.2wt%. In recycled deformed aluminum alloy, Al≥95wt%, Fe is 0.2-1wt%, Si≤5wt%, Cu≤1wt%, Mg≤3wt%, Mn≤0.3wt%, Ti≤0.3wt%, Cr≤0.3wt%, V≤0.3wt%, Zn≤6wt%, Pb≤0.2wt%, and organic matter≤0.2wt%.

[0044] The recycled aluminum can be pre-processed, such as sorting, crushing, magnetic separation and iron removal, cleaning, etc. The composition and content of the recycled aluminum can also be tested for the first time, and the composition and content of the recycled aluminum can be tested for the first time using a photoelectric direct reading spectrometer or chemical analysis method. In this way, the recycled aluminum with similar composition and content can be mixed together according to the test results to avoid the situation where the mixed recycled aluminum has too complex composition, excessive content of certain elements, or substandard content of certain elements.

[0045] Industrial silicon may include Si1101, Si2202, Si3303, Si4110, Si4210, Si4410, Si5210, Si5530, etc. Fe, Ca, Al, Mn, Ti, Cr, and V, etc. are impurities in industrial silicon.

[0046] In Si1101, Si≥99.79wt%, Fe≤0.10wt%, Al≤0.1wt%, Ca≤0.01wt%, Mn≤0.3wt%, Ti≤0.1wt%, Cr≤0.1wt%, V≤0.1wt%; In Si2202, Si≥99.58wt%, Fe≤0.2wt%, Al≤0.2wt%, Ca≤0.02wt%, Mn≤0.3wt%, Ti≤0.1wt%, Cr≤0.1wt%, V≤0.1wt%; In Si3303, Si≥99.37wt%, Fe≤0.3wt%, Al≤0.3wt%, Ca≤0.03wt%, Mn≤0.3wt%, Ti≤0.1wt%, Cr≤0.1wt%, V≤0.1wt%; In Si4110, Si≥99.40wt%, Fe≤0.4wt%, Al≤0.1wt%, Ca≤0.1wt%, Mn≤0.3wt%, Ti≤0.1wt%, Cr≤0.1wt%, V≤0.1wt%; In Si4210, Si≥99.30wt%, Fe≤0.4wt%, Al≤0.2wt%, Ca≤0.1wt%, Mn≤0.3wt%, Ti≤0.1wt%, Cr≤0.1wt%, V≤0.1wt%; In Si4410, Si≥99.10wt%, Fe≤0.4wt%, Al≤0.4wt%, Ca≤0.1wt%, Mn≤0.3wt%, Ti≤0.1wt%, Cr≤0.1wt%, V≤0.1wt%; In Si5210, Si≥99.20wt%, Fe≤0.5wt%, Al≤0.2wt%, Ca≤0.1wt%, Mn≤0.3wt%, Ti≤0.1wt%, Cr≤0.1wt%, V≤0.1wt%; In Si5530, Si≥98.70wt%, Fe≤0.5wt%, Al≤0.5wt%, Ca≤0.3wt%, Mn≤0.3wt%, Ti≤0.1wt%, Cr≤0.1wt%, and V≤0.1wt%.

[0047] In steel waste, Fe is 95-97wt%, C is 0.04-2.3wt%, Si is 0.04-2.3wt%, Mn is 0.04-2.3wt%, P is 0.04-2.3wt%, S is 0.04-2.3wt%, Sn≤0.6wt%, Ti≤0.1wt%, Cr≤0.1wt%, V≤0.1wt%. C, Si, Mn, Ti, Cr, V, P, Sn and S are impurities in steel waste.

[0048] In magnesium alloy waste, Mg is 96.8-99.9wt%, Al is 1-3wt%, Zn is 0.1-1wt%, Mn≤0.1wt%, Ti≤0.1wt%, and Zr≤0.1wt%. Al, Zn, Mn, Ti, and Zr are impurities in magnesium alloy waste.

[0049] Waste recycling can not only save costs, but also achieve the sustainable development of aluminum resources, magnesium resources, silicon resources and iron resources. Since most of the raw materials are waste materials or recycled raw materials, more types of impurities with high total content will be introduced into the present invention, which has the disadvantages of more types of impurities and higher total impurity content. Of course, it is not ruled out that a certain impurity or several impurities have high content and are difficult to remove. When the present invention uses recycled aluminum, industrial silicon, steel waste, and magnesium alloy waste as raw materials, at least the following elements will be introduced: Al, Fe, Si, Cu, Mn, Ti, Cr, V, Mg, Zn, Zr, Pb, Ca, C, P, Sn, and S, etc. When recycled aluminum, industrial silicon, steel waste, and magnesium alloy waste are used as raw materials and Zn, Zr, Cu, Mn, Cr, V, and Ca are not added to the recycled aluminum melt, the high-toughness and high-thermal-conductivity die-casting aluminum alloy may contain 0.0001-0.2% by mass of Zn, 0.0001-0.1% by mass of Zr, 0.0001-0.2% by mass of Cu, 0.0001-0.1% by mass of Mn, 0.0001-0.2% by mass of Cr, 0.0001-0.1% by mass of V, and 0.0001-0.1% by mass of Ca.

[0050] The preparation method of the high-toughness and high-thermal-conductivity die-cast aluminum alloy of the present invention uses recycled aluminum, industrial silicon, steel waste, and magnesium alloy waste as raw materials to reduce costs. The addition of a certain amount of Sr, RE, Ti, B, Zn, and Cr raw materials, combined with multiple refining treatments, boronization treatments, and aging treatments, can achieve better strength, elongation, and thermal conductivity. The high-toughness and high-thermal-conductivity die-cast aluminum alloy has a tensile strength greater than 420MPa, a yield strength greater than 335MPa, an elongation greater than 10%, and a thermal conductivity coefficient generally required to be greater than 160W / mK. Specifically: (1) Industrial silicon can provide Si. When the mass percentage of Si is 6-11%, it can improve the fluidity and density of aluminum alloy, thereby improving the forming performance and mechanical properties of aluminum alloy; Si within this content range can also significantly improve the elongation of aluminum alloy; when the mass percentage of Si exceeds 12%, coarse elemental Si will appear, which will sharply reduce the elongation of aluminum alloy; (2) Iron and steel waste can provide Fe. When the mass percentage of Fe is 0.05-0.8%, Fe can reduce the sticking tendency of aluminum alloy castings and improve the forming performance of aluminum alloys. Fe can react with other elements to form a second phase to avoid the adverse effect of Fe and other elements dissolved in the aluminum matrix on the thermal conductivity of aluminum alloys. Specifically, Fe can react with Al, Si, Mg, Cu, Mn, Ni, B, etc. to form Al3Fe, AlFeSi, AlFeMgSi, AlFeSiCu, AlFeSiNi, AlFeMgSiNi, AlFeMnSi, FeNiAl9, AlFeSiB and other second phases. However, the presence of β-iron-rich phase in the aluminum matrix will reduce the elongation and thermal conductivity of aluminum alloys. (3) Magnesium alloy scrap can provide Mg. When the mass percentage of Mg is 0.2-3%, Mg can greatly improve the mechanical properties of aluminum alloy. Mg can react with other elements to form a second phase to avoid the adverse effect of Mg element dissolved in the aluminum matrix on the thermal conductivity of aluminum alloy. Specifically, Mg can react with Al, Fe, Si, Cu, Zn, B, Ni, etc. to form second phases such as MgB, Mg2Si, Mg2Zn, Mg2SiZn, (CuMg)Al2, AlFeMgSi, AlFeMgSiNi, etc. Mg can also promote the precipitation of second phases such as CuAl2, AlFeSiCu, Al2CuZn, (CuMg)Al2, increase their volume fraction and dispersion, reduce the solid solubility of the above elements in the aluminum matrix, and improve the thermal conductivity of aluminum alloy. (4) The mass percentage of Sr is not more than 0.1%. Sr can be modified through heterogeneous nucleation theory or twin valley mechanism to refine grains, second phases such as eutectic silicon, and precipitation phases to improve the elongation and thermal conductivity of aluminum alloys; Sr can also transform β-AlFeSi phase into Chinese character α-AlFeSi phase to improve the mechanical properties of aluminum alloys; Sr can also promote the precipitation of CuAl2, Mg2Si and other phases to reduce the solid solubility of these alloying elements in the aluminum matrix to improve the thermal conductivity of aluminum alloys; (5) The mass percentage content of Ti is not more than 0.3%. Ti can improve the strength and elongation of aluminum alloys. Specifically, the TiAl2 phase generated by the reaction of Ti and Al can serve as a non-spontaneous core during crystallization, which can refine the grains, second phases and precipitated phases to improve the strength and elongation of aluminum alloys; (6) The mass percentage content of B is not more than 0.05%. B can transform the β-AlFeSi phase into the Chinese character α-AlFeSi phase to improve the mechanical properties of the aluminum alloy; B can remove / improve the Fe phase and remove Mn+Ti+V+Cr through boriding reaction to purify the mixed solution, thereby improving the elongation and thermal conductivity of the aluminum alloy; B can also refine the grains and modify and refine the elemental Si to further improve the strength and elongation of the aluminum alloy; B can also react with other elements to form a second phase to avoid the adverse effect of B dissolved in the aluminum matrix on the thermal conductivity of the aluminum alloy. Specifically, B can react with Al, Fe, Si, Mg, Cu, etc. to form second phases such as AlFeSiB, MgB, CuB, etc.; B can also inhibit the segregation of Ti3Al. When Ti and B are used together, the effect is better, which significantly improves the strength and elongation of the aluminum alloy; (7) The mass percentage of Zn is not more than 1%. Zn can improve the strength of aluminum alloys; Zn can eliminate elemental Si to reduce the adverse effects of elemental Si on the properties of aluminum alloys; Zn can also promote the precipitation of second phases such as Mg2Si, Al2Cu, and Mg3Sb2, thereby improving strength and thermal conductivity; (8) The mass percentage content of RE is not more than 0.2%. The distribution area of ​​RE is consistent with that of Fe phase, and RE can form a rare earth active film on the surface of Fe phase to prevent the formation of hard and brittle β-AlFeSi phase on the grain boundary. RE is a surface active element with a radius larger than that of Al. It cannot enter the α-Al lattice, but can be concentrated on the grain boundary or adsorbed on the solid-liquid interface to form partial supercooling, which increases the chance of dendrite melting, thereby refining α-Al to improve the elongation of aluminum alloy. (9) The mass percentage of Cr is 0.0001-0.5%. Cr can transform β-Fe phase into α-Fe phase to eliminate the harmful effects of Fe; Cr forms (CrFe)Al7 and (CrMn)Al in the recycled aluminum melt. 12, α-Al(FeMnCr)Si phase has strong thermal stability, which can improve the thermal conductivity of aluminum alloy, and can also hinder the nucleation and growth process of recrystallization, thereby improving the elongation of aluminum alloy; (10) The two refining treatments and the boronization treatment can remove impurity elements such as oxide slag and organic matter, and can also remove low melting point impurity elements such as Pb, Sn, Fe, Mn, C, P, S and other impurities, so that the content of Pb, Sn, C, P and S is reduced to below 0.001% or even 0%, thereby preventing Pb, Sn, coarse βFe, Mn, C, P, S and the like from affecting the strength, elongation and thermal conductivity of the aluminum alloy; (11) The aging treatment can further improve the strength, elongation and thermal conductivity of the aluminum alloy.

[0051] In summary, the present invention adds a certain amount of industrial silicon, steel waste, magnesium alloy waste, Sr, RE, Ti, B, Zn, and Cr into the recycled aluminum melt. Si, Fe, Mg, Sr, RE, Ti, B, Zn, and Cr interact with each other as a whole. After multiple refining treatments, boronization treatments, and aging treatments, a high-toughness and high-thermal-conductivity die-casting aluminum alloy with excellent comprehensive performance can be obtained. The content of Si is not high, and it can provide a higher elongation while ensuring fluidity; Sr and B can modify and refine Si, Zn can eliminate elemental Si, and Sr, B, and Zn work together to reduce the adverse effects of Si; Fe can improve the demoulding performance of aluminum alloys; Sr, RE, B, and Cr can not only transform β-Fe into α-Fe phase when they cooperate with each other, but also prevent the formation of β-Fe phase, avoiding β-Fe phase from reducing the elongation and thermal conductivity of aluminum alloys; Sr, RE, Ti, B, Zn, and Cr can further refine α-Al, the second phase, and the precipitated phase to further improve the elongation of aluminum alloys; Mg, Sr, and Zn can also promote the precipitation of the second phase to reduce the solid solubility of these alloy elements in the aluminum matrix to improve the thermal conductivity of aluminum alloys. In this way, while ensuring strength and demoulding performance, aluminum alloys with excellent elongation and thermal conductivity can be obtained.

[0052] Transition metal elements, such as Mn, Ti, Cr, V, etc., have a great influence on the thermal conductivity of aluminum alloys. They are usually restricted to be added as impurities to aluminum alloys with high requirements for high thermal performance. Excessive impurity content or impurity treatment will also reduce the elongation of aluminum alloys. The die-cast aluminum alloy of the present invention uses recycled aluminum, industrial silicon, steel waste, and magnesium alloy waste as raw materials. These low-priced raw materials inevitably contain the above-mentioned Mn, Ti, Cr, and V impurities, and the situation in which at least one of Mn, Ti, Cr, and V has a high content is not excluded. It will cost more to completely remove or reduce the above-mentioned impurities to a lower level (reduced to less than 0.001wt% or even less than 0.0001wt%). In order not to increase the cost, some impurities are usually not completely removed or reduced to a lower level, which is also the reason why many aluminum alloys using recycled aluminum as raw materials have low elongation and thermal conductivity. However, the present application uses industrial silicon, steel waste, and magnesium alloy waste as raw materials, and cooperates with two refining treatments and boronization treatment, and the combined effects of Sr, RE, Ti, B, Zn, and Cr to produce a die-cast aluminum alloy with excellent comprehensive performance. There is no need to use Mn, Ti, Cr, and V as impurities, nor is there any need to try hard to remove Mn, Ti, Cr, and V. On the basis of controlling costs, an Al-Si series die-cast aluminum alloy with excellent comprehensive performance is obtained. Among them, Ti, Cr, and V can be used as strengthening elements to improve the strength of the aluminum alloy, and Mn can improve the coarse β-Fe to improve the elongation of the aluminum alloy.

[0053] It is understandable that Fe, Mn, Ti, V, and Cr in aluminum alloys will cause a sharp drop in thermal conductivity. During the boriding treatment, B and Fe, Mn, Ti, V, and Cr can form insoluble borides with a large specific gravity, which can be precipitated and removed; at the same time, Fe, Mn, Ti, V, and Cr dissolved in aluminum can also form compounds that gather on the grain boundaries, greatly improving the mechanical properties and electrical conductivity. However, compared with alloys without Fe, Mn, Ti, V, and Cr, although the mechanical properties are improved, the thermal conductivity is still reduced.

[0054] The method for preparing the high-toughness and high-thermal-conductivity die-cast aluminum alloy further comprises the step of adding at least one of SiC, AlTiC, and BN to the recycled aluminum melt. In the high-toughness and high-thermal-conductivity die-cast aluminum alloy, the mass percentage content of SiC is 0-1%, the mass percentage content of TiC is 0-1%, and the mass percentage content of BN is 0-0.5%. The mass percentage content of SiC and TiC can be specifically 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, or 1%. The mass percentage content of BN can be specifically 0.01%, 0.05%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.3%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, 0.4%, 0.41%, 0.42%, 0.43%, 0.44%, 0.45%, 0.46%, 0.47%, 0.48%, 0.49%, or 0.5%.

[0055] SiC, AlTiC, and BN all have good refining effects. When used in combination, the best refining effect can be achieved by reducing their respective contents. When SiC is used in combination with Ti and B, a C-TiB2 particle complex is formed at the SiC-Al interface. The C atoms in SiC tend to enhance the adhesion energy of the C-TiB2 / Al interface, which makes the originally long strips of TiAl3 broken and shortened to avoid the enrichment and growth of TiAl3, greatly enhancing the composite refining effect; BN disperses AlB2 and AlN nano-nucleation at the aluminum matrix interface and grain boundary, which can refine the grains and promote uniform nucleation of grains to improve the elongation of aluminum alloys; under the action of SiC, Ti, B, and BN, AlTiC is not easy to aggregate and has a better effect of fine grain strengthening.

[0056] In one embodiment, Mo, Co, and Be elements can be added to the mixed melt. Of course, one or more of Mo, Co, and Be elements can also be added. The cooperation of Mn, Cr, RE, Mo, Co, Be, and Sr elements can not only reduce the maximum solubility of each other in the aluminum matrix to improve thermal conductivity, but also promote the reaction of Mn and Fe. Mn can occupy the position of Fe element in the second phase, making the Fe-containing phase more dispersed and fine, and promoting the effect of metamorphic Fe. Mn, Cr, RE, Mo, Co, Be, and Sr elements can also generate a fine and dispersed α-Al(MnFeX)Si phase (wherein X is at least one of Cr, RE, Mo, Co, Be, and Sr) to improve the elongation and thermal conductivity of the aluminum alloy.

[0057] At this time, in the high toughness and high thermal conductivity die-cast aluminum alloy, the mass percentage content of Mn can be 0.0001-0.1%, specifically 0.0001%, 0.0002%, 0.0003%, 0.0004%, 0.0005%, 0.0006%, 0.0007%, 0.0008%, 0.0009%, 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07% , 0.08%, 0.09%, or 0.1%; the mass percentage content of Mo can be 0-0.3%, specifically 0.0005%, 0.0006%, 0.0007%, 0.0008%, 0.0009%, 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%, 0.21%, 0. 22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, or 0.3%; the mass percentage content of Co can be 0-0.5%, specifically 0.0001%, 0.0005%, 0.0006%, 0.0007%, 0.0008%, 0.0009%, 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35 %, 0.4%, 0.45%, or 0.5%; the mass percentage content of Be can be 0-0.2%, specifically 0.0001%, 0.0005%, 0.0006%, 0.0007%, 0.0008%, 0.0009%, 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, or 0.2%.

[0058] Ni element can be added to the mixed melt. The mass percentage content of Ni can be 0-2.5%, specifically 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.45%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.78%, 0.85%, 0.9%, 0.95%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, or 2.5%. Ni can refine grains, form second phases and precipitate phases to improve the elongation of aluminum alloys; Ni can react with other elements to form second phases to avoid the adverse effects of Ni dissolved in the aluminum matrix on the thermal conductivity of aluminum alloys. Specifically, Ni can react with Al, Fe, Mg, Si, etc. to form second phases such as Al3Ni, AlFeSiNi, AlFeMgSiNi, FeNiAl9, etc.; Ni can also promote the precipitation of phases such as CuAl2 and (CuMg)Al2, increase the volume fraction and dispersion of the precipitated phases, reduce the solubility of alloy elements in the aluminum matrix, and improve the thermal conductivity of aluminum alloys; Ni can promote precipitation with Cu and Mg to improve the thermal conductivity and mechanical properties of aluminum alloys; Mg content and Ni content can be proportional. When the Mg content is high, the Ni content can also be set higher to generate more AlFeMgSiNi dispersed second phases to significantly improve the strength of aluminum alloys.

[0059] In the high-toughness and high-thermal-conductivity die-cast aluminum alloy, when the mass percentage of Ni reaches more than 2%, a primary Al-Ni-Cu ternary compound and a eutectic Al-Ni-Cu ternary compound will be formed in the aluminum alloy structure, which can greatly improve the thermal conductivity and strength of the aluminum alloy. If the high-toughness and high-thermal-conductivity die-cast aluminum alloy also contains Mn (Mn can come from waste), a eutectic Al-Si-Cu-Ni-Mn quinary compound will also be crystallized, reducing the solid solubility of Mn in the matrix, further improving the thermal conductivity and strength of the aluminum alloy.

[0060] The method for preparing the high-strength Al-Si die-casting aluminum alloy also includes the step of adding V to the recycled aluminum melt, and the mass percentage content of V is 0.005-0.2%. The mass percentage content of V can specifically be 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, or 0.2%. Although V will reduce thermal conductivity, V can improve the elongation and strength of aluminum alloys. Specifically, V forms Al3V, Al4V, and Al6V in aluminum alloys. 10 V, VA11, VB2, AlB 2、 Al(VB)2 is a refractory compound that can refine grains and perform dispersion strengthening, thereby improving the strength and elongation of aluminum alloys. Especially in Al-Si alloys with Si content greater than 4%, the addition of Si can reduce the melting point of the Al melt, making the liquidus temperature lower than the Al-B eutectic temperature, and promoting the formation of Al(VB)2 in the Al-Si alloy. Under the action of Si, the Al(VB)2 structure changes, the stability is improved, and the heterogeneous nucleation ability is enhanced, which more significantly promotes grain refinement.

[0061] On the basis that most of the elements (except V in the present invention) have been dissolved in the aluminum matrix to avoid adverse effects on thermal conductivity, and some elements (such as B, Ni, Mn, Cr, RE, Mo, Co, Be, SiC, AlTiC, Ti, B, BN, and Sr, etc.) have significantly improved thermal conductivity, V can also be added to the recycled aluminum melt as a raw material to improve the elongation and strength of the aluminum alloy. When Ti, V, Cr, and Ni are added at the same time, the original block or thick strip Al-Ti, Al-V, Al-Cr, and Al-Ni compounds will be converted into dot-shaped, small, blocky, and complex Al-Ti-V-Cr-Ni compounds distributed in the crystal and at the grain boundary. In this way, Ti, V, and Cr can be added to the recycled aluminum melt as raw materials.

[0062] At least one of Cu, Zr, and Ca may be added to the recycled aluminum melt. At this time, the high-toughness and high-thermal-conductivity die-cast aluminum alloy contains 0.0001-1% Cu by mass, 0.0001-0.5% Zr by mass, and 0.0001-0.3% Ca by mass. Cu, Zr, and Ca can all improve the strength of the aluminum alloy. Ca can also remove H in the recycled aluminum melt, refine the grains and the second phase, and improve the morphology of the β-Fe phase and eutectic silicon to improve the elongation of the aluminum alloy. Zr can also refine the grains, the second phase, and the precipitated phase to improve the elongation of the aluminum alloy. Elements such as Cu, Zr, Ca introduced from waste materials can react with other elements to form Al2CuZn, AlFeSiCu, (CuMg)Al2, AlCaCu, AlCa, Mg2SiZn, Al2CuZn, MgZn2, Al3Zr, etc., thereby avoiding the adverse effects of Cu, Zr, Ca in the aluminum matrix on the strength, elongation and thermal conductivity of the aluminum alloy.

[0063] The mass percentage content of Cu may be 0.0001%, 0.0005%, 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, or 1%. The mass percentage content of Zr can be 0.0001%, 0.0005%, 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.30%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, 0.40%, 0.40%, 0.41%, 0.42%, 0.43%, 0.44%, 0.45%, 0.46%, 0.47%, 0.48%, 0.49%, 0.5 %, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.3%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, 0.4%, 0.41%, 0.42%, 0.43%, 0.44%, 0.45%, 0.46%, 0.47%, 0.48%, 0.49%, or 0.5%. The mass percentage content of Ca may be 0.0001%, 0.0005%, 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, or 0.3%.

[0064] It can be understood that when the Cu content is higher, it is more conducive to the formation of primary Al-Ni-Cu ternary compound, eutectic Al-Ni-Cu ternary compound and eutectic Al-Si-Cu-Ni-Mn quinary compound.

[0065] The method for preparing the high-toughness and high-thermal-conductivity die-cast aluminum alloy also includes the step of adding at least one of Te, Ag, Sb, Bi and Nb to the recycled aluminum melt. In the high-toughness and high-thermal-conductivity die-cast aluminum alloy, the mass percentage content of Te is 0-0.2%, the mass percentage content of Ag is 0-0.2%, the mass percentage content of Sb is 0-0.5%, the mass percentage content of Bi is 0-0.2%, and the mass percentage content of Nb is 0-0.3%. The refining effect of Te and Ag can refine the second phase to improve the elongation of the aluminum alloy. Bi and Sb can improve the strength of the aluminum alloy. Nb can refine the grains and the second phase to achieve the effect of improving the elongation. Bi can effectively prevent sodium embrittlement, and even if the mass percentage content of Mg is high, such as 2-3%, sodium embrittlement will not occur; Bi can also reduce the surface tension of the aluminum melt and reduce the contact angle between Al and Si, so that the growth front of Si is more easily suppressed by Al, thereby reducing the size of eutectic silicon.

[0066] The mass percentage content of Te, Ag and Bi can be 0.0001%, 0.0005%, 0.001%, 0.005%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, or 0.2%. The mass percentage content of Nb can be 0.0001%, 0.0005%, 0.001%, 0.005%, 0.01%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, or 0.3%. The mass percentage content of Sb can be 0.0001%, 0.0005%, 0.001%, 0.005%, 0.01%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.30%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, 0.40%, 0.41%, 0.42%, 0.43%, 0.44%, 0.45%, 0.46%, 0.47%, 0.48%, 0.49%, 0.50%, 0.51%, 0.52%, 0.53%, 0.54%, 0.55%, 0.56%, 0.57%, 0.58%, 0.59%, 0.60%, 0.61%, 0.62%, 0.63%, 0.64%, 0.65%, 0.6 7%, 0.18%, 0.19%, 0.2%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.3%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, 0.4%, 0.41%, 0.42%, 0.43%, 0.44%, 0.45%, 0.46%, 0.47%, 0.48%, 0.49%, or 0.5%.

[0067] The present invention also provides a high-toughness and high-thermal-conductivity die-cast aluminum alloy prepared by the above-mentioned method for preparing the high-toughness and high-thermal-conductivity die-cast aluminum alloy. The high-toughness and high-thermal-conductivity die-cast aluminum alloy contains Si with a mass percentage content of 6-11%, Fe with a mass percentage content of 0.05-0.8%, Mg with a mass percentage content of 0.2-3%, Sr with a mass percentage content of 0.001-0.1%, RE with a mass percentage content of 0-0.2%, Ti with a mass percentage content of 0-0.3%, B with a mass percentage content of 0-0.05%, Zn with a mass percentage content of 0-1%, and Cr with a mass percentage content of 0.0001-0.5%. The high-toughness and high-thermal-conductivity die-cast aluminum alloy also contains at least one of Mo, Co, Be, Cu, V, Ca, Zr, Te, Ag, Sb, Bi, Nb, SiC, AlTiC, and BN. Among them, the mass percentage content of Mo can be 0-0.3%, the mass percentage content of Co can be 0-0.5%, the mass percentage content of Be can be 0-0.2%, the mass percentage content of Cu is 0.0001-1%, the mass percentage content of V is 0.005-0.2%, the mass percentage content of Ca is 0.0001-0.3%, the mass percentage content of Zr is 0.0001-0.5%, the mass percentage content of Te is 0-0.2%, the mass percentage content of Ag is 0-0.2%, the mass percentage content of Sb is 0-0.5%, the mass percentage content of Bi is 0-0.2%, the mass percentage content of Nb is 0-0.3%, the mass percentage content of SiC is 0-1%, the mass percentage content of TiC is 0-1%, and the mass percentage content of BN is 0-0.5%.

[0068] The present invention also provides a structural part, at least part of which is made of the high-toughness and high-thermal-conductivity die-cast aluminum alloy or the high-toughness and high-thermal-conductivity die-cast aluminum alloy prepared by the preparation method. The structural part can be applied to the filter housing of a communication base station, the heat dissipation substrate of a communication base station, the cabinet shell of a communication base station, the three-electric structural part housing of an automobile, the housing of an automobile, the heat sink of a computer device, the middle plate of a mobile phone, the housing of a mobile phone, the heat sink of an LED lamp, the thin parts of 5G products, aerospace, high-speed rail, ships, mobile devices, household appliances, chemical industry, daily necessities, construction, etc.

[0069] Embodiment 1 Heating the recycled aluminum to obtain a recycled aluminum melt; The temperature is adjusted to 740° C., and industrial silicon and steel waste are added to the recycled aluminum melt to obtain a mixed melt; The mixed melt is subjected to a boronization treatment and a first refining treatment, wherein the boronization agent of the boronization treatment is potassium fluoroborate, and the mass ratio of potassium fluoroborate to the mixed melt is 0.001:1; the temperature of the first refining treatment is 740°C, the time is 60 minutes, the refining agent is sodium chloride, and the mass ratio of sodium chloride to the mixed melt is 0.0001:1; The temperature is adjusted to 710°C, and after adding magnesium alloy scrap, Sr, RE, Cr, Zn, and Al-Ti-B alloy to the mixed melt after the first refining treatment, the mixed melt is subjected to a second refining treatment, a slag removal treatment, a degassing treatment, and a standing treatment. After the standing treatment, the surface scum is scraped off, the temperature of the second refining treatment is 690°C, the time is 10 minutes, the refining agent of the second refining treatment is sodium chloride, and the mass ratio of sodium chloride to the mixed melt is 0.001:1; and The components and contents of the mixed melt after the static treatment are measured. When the components and contents of the mixed melt after the static treatment meet the standards, the mixed melt after the static treatment is subjected to die casting to obtain a high-toughness and high-thermal-conductivity die-cast aluminum alloy. The high-toughness and high-thermal-conductivity die-cast aluminum alloy contains 11% Si by mass, 0.2% Fe by mass, 0.2% Mg by mass, 0.01% Sr by mass, 0.01% RE by mass, 0.01% Ti by mass, 0.02% B by mass, 0.02% Zn by mass, and 0.06% Cr by mass.

[0070] Embodiment 2 Heating the recycled aluminum to obtain a recycled aluminum melt; The temperature is adjusted to 860° C., and industrial silicon and steel waste are added to the recycled aluminum melt to obtain a mixed melt; The mixed melt is subjected to a boronization treatment and a first refining treatment, wherein the boronizing agent of the boronization treatment is an aluminum-boron alloy, the mass ratio of the aluminum-boron alloy to the mixed melt is 0.002:1, the temperature of the first refining treatment is 800°C, the time is 20 minutes, the refining agent includes 50wt% of sodium chloride, 40wt% of calcium fluoride, and 10wt% of rare earth Ce, and the mass ratio of the refining agent to the mixed melt is 0.0001:1; The temperature is adjusted to 750°C, and after adding magnesium alloy scrap, Sr, RE, Cr, Zn, and Al-Ti-B alloy to the mixed melt after the first refining treatment, the mixed melt is subjected to a second refining treatment, a slag removal treatment, a degassing treatment, and a standing treatment. After the standing treatment, the surface scum is scraped off, the temperature of the second refining treatment is 690°C, the time is 10 minutes, the refining agent of the second refining treatment includes 50wt% of sodium chloride, 40wt% of calcium fluoride, and 10wt% of rare earth Ce, the mass ratio of the refining agent to the mixed melt is 0.0001:1, and the mass ratio of the refining agent to the mixed melt is 0.0001:1; and The components and contents of the mixed melt after the static treatment are measured. When the components and contents of the mixed melt after the static treatment meet the standards, the mixed melt after the static treatment is subjected to die casting and aging treatment to obtain a high-toughness and high-thermal-conductivity die-cast aluminum alloy. The aging treatment includes a primary low-temperature electric field aging treatment and a secondary high-temperature aging treatment, wherein the primary low-temperature electric field aging treatment is at a temperature of 50°C, a time of 50h, and an electric field strength of 5V / cm; the secondary high-temperature aging treatment is at a temperature of 140°C, and a time of 50h. The high-toughness and high-thermal-conductivity die-cast aluminum alloy contains 11% Si by mass, 0.3% Fe by mass, 1% Mg by mass, 0.02% Sr by mass, 0.02% RE by mass, 0.02% Ti by mass, 0.02% B by mass, 0.05% Zn by mass, 0.04% Cr by mass, 0.005% Zr by mass, 0.01% Cu by mass, 0.01% Mn by mass, 0.005% V by mass, 0.0001% Ca by mass, and 0.1% SiC by mass.

[0071] Embodiment 3 Heating the recycled aluminum to obtain a recycled aluminum melt; The temperature is adjusted to 820° C., and industrial silicon and steel waste are added to the recycled aluminum melt to obtain a mixed melt; The mixed melt is subjected to a boronization treatment and a first refining treatment, wherein the boronization agent of the boronization treatment is an aluminum-boron alloy, and the mass ratio of the aluminum-boron alloy to the mixed melt is 0.002:1; the temperature of the first refining treatment is 740°C, the time is 60 minutes, the refining agent is sodium aluminum fluoride, and the mass ratio of sodium aluminum fluoride to the mixed melt is 0.0002:1; The temperature is adjusted to 780°C, and after adding magnesium alloy scrap, Sr, RE, Cr, Zn, and Al-Ti-B alloy to the mixed melt after the first refining treatment, the mixed melt is subjected to a second refining treatment, a slag removal treatment, a degassing treatment, and a standing treatment. After the standing treatment, the surface scum is scraped off. The temperature of the second refining treatment is 695°C, the time is 15 minutes, the refining agent includes 60wt% of potassium chloride, 10wt% of rare earth lanthanum, and 30wt% of potassium fluoride, and the mass ratio of the refining agent to the mixed melt is 0.001:1; and The components and contents of the mixed melt after the static treatment are measured. When the components and contents of the mixed melt after the static treatment meet the standards, the mixed melt after the static treatment is subjected to die casting and aging treatment to obtain a high-toughness and high-thermal-conductivity die-cast aluminum alloy. The aging treatment includes a primary low-temperature electric field aging treatment and a secondary high-temperature aging treatment, wherein the primary low-temperature electric field aging treatment is at a temperature of 55°C, a time of 1.5h, and an electric field strength of 30V / cm; the secondary high-temperature aging treatment is at a temperature of 145°C and a time of 5h. The high-toughness and high-thermal-conductivity die-cast aluminum alloy contains 9% Si by mass, 0.4% Fe by mass, 0.8% Mg by mass, 0.05% Sr by mass, 0.03% RE by mass, 0.05% Ti by mass, 0.01% B by mass, 0.1% Zn by mass, 0.1% Cr by mass, 0.02% Mo by mass, 0.02% Co by mass, 0.02% Be by mass, and 0.001% Mn by mass.

[0072] Embodiment 4 Heating the recycled aluminum to obtain a recycled aluminum melt; The temperature is adjusted to 760° C., and industrial silicon and steel waste are added to the recycled aluminum melt to obtain a mixed melt; The mixed melt is subjected to a boronizing treatment and a first refining treatment, wherein the boronizing agent of the boronizing treatment comprises 60wt% of aluminum-boron alloy and 40wt% of potassium fluoroborate, the mass ratio of the boronizing agent to the mixed melt is 0.003:1, the temperature of the first refining treatment is 780°C, the time is 30min, the refining agent is calcium fluoride, and the mass ratio of calcium fluoride to the mixed melt is 0.0003:1; The temperature is adjusted to 720°C, and after adding magnesium alloy scrap, Sr, RE, Cr, Zn, and Al-Ti-B alloy to the mixed melt after the first refining treatment, the mixed melt is subjected to a second refining treatment, a slag removal treatment, a degassing treatment, and a standing treatment. After the standing treatment, the surface scum is scraped off. The temperature of the second refining treatment is 700°C, the time is 20 minutes, the refining agent includes 50wt% of potassium chloride and 50wt% of calcium fluoride, and the mass ratio of the refining agent to the mixed melt is 0.03:1; and The components and contents of the mixed melt after the static treatment are measured. When the components and contents of the mixed melt after the static treatment meet the standards, the mixed melt after the static treatment is subjected to die casting and aging treatment to obtain a high-toughness and high-thermal-conductivity die-cast aluminum alloy. The aging treatment includes a primary low-temperature electric field aging treatment and a secondary high-temperature aging treatment, wherein the primary low-temperature electric field aging treatment is performed at a temperature of 100°C, a time of 10 hours, and an electric field strength of 10V / cm; the secondary high-temperature aging treatment is performed at a temperature of 150°C, and a time of 10 hours. The high-toughness and high-thermal-conductivity die-cast aluminum alloy contains 8% Si by mass, 0.6% Fe by mass, 1% Mg by mass, 0.03% Sr by mass, 0.05% RE by mass, 0.1% Ti by mass, 0.02% B by mass, 0.2% Zn by mass, 0.05% Cr by mass, 1% Ni by mass, 0.01% Be by mass, and 0.1% Mn by mass.

[0073] Embodiment 5 Heating the recycled aluminum to obtain a recycled aluminum melt; The temperature is adjusted to 760° C., and industrial silicon and steel waste are added to the recycled aluminum melt to obtain a mixed melt; The mixed melt is subjected to a boronizing treatment and a first refining treatment, wherein the boronizing agent of the boronizing treatment comprises 50wt% of aluminum-boron alloy and 50wt% of potassium fluoroborate, and the mass ratio of the boronizing agent to the mixed melt is 0.004:1; the temperature of the first refining treatment is 780°C, the time is 40min, the refining agent comprises 40wt% of potassium chloride, 50wt% of potassium fluoride, and 10wt% of rare earth Ce, and the mass ratio of the refining agent to the mixed melt is 0.0004:1; The temperature is adjusted to 750° C., and after adding magnesium alloy scrap, Sr, RE, Cr, Zn, and Al-Ti-B alloy to the mixed melt after the first refining treatment, the mixed melt is subjected to a second refining treatment, a slag removal treatment, a degassing treatment, and a standing treatment. After the standing treatment, the surface scum is scraped off, the temperature of the second refining treatment is 750° C., the time is 20 min, the refining agent includes 80wt% of potassium chloride, 2wt% of scandium oxide, and 18wt% of potassium fluoride, and the mass ratio of the refining agent to the mixed melt is 0.1:1; and The components and contents of the mixed melt after the static treatment are measured. When the components and contents of the mixed melt after the static treatment meet the standards, the mixed melt after the static treatment is subjected to die casting and aging treatment to obtain a high-toughness and high-thermal-conductivity die-cast aluminum alloy. The aging treatment includes a primary low-temperature electric field aging treatment and a secondary high-temperature aging treatment, wherein the primary low-temperature electric field aging treatment is at a temperature of 65°C, a time of 20 hours, and an electric field strength of 20V / cm; the secondary high-temperature aging treatment is at a temperature of 150°C, and a time of 20 hours. The high-toughness and high-thermal-conductivity die-cast aluminum alloy contains 7% Si by mass, 0.8% Fe by mass, 2% Mg by mass, 0.02% Sr by mass, 0.1% RE by mass, 0.2% Ti by mass, 0.01% B by mass, 0.2% Zn by mass, 0.1% Cr by mass, 0.01% Zr by mass, 0.1% Cu by mass, and 0.001% Ca by mass.

[0074] Embodiment 6 The mold is surface treated to form a 1 mm boron carbide layer on the parting surface of the mold; Heating the recycled aluminum to obtain a recycled aluminum melt; The temperature is adjusted to 800° C., and industrial silicon and steel waste are added to the recycled aluminum melt to obtain a mixed melt; The mixed melt is subjected to a boronization treatment and a first refining treatment, wherein the boronization agent of the boronization treatment is potassium fluoroborate, and the mass ratio of the potassium fluoroborate to the mixed melt is 0.005:1; the temperature of the first refining treatment is 810°C, the time is 40 minutes, the refining agent is potassium fluoroborate, and the mass ratio of potassium fluoroborate to the mixed melt is 0.0005:1; The temperature is adjusted to 730° C., and after adding magnesium alloy scrap, Sr, RE, Cr, Zn, and Al-Ti-B alloy to the mixed melt after the first refining treatment, the mixed melt is subjected to a second refining treatment, a slag removal treatment, a degassing treatment, and a standing treatment. After the standing treatment, the surface scum is scraped off. The temperature of the second refining treatment is 730° C., the time is 30 minutes, the refining agent includes 80wt% of potassium chloride, 5wt% of ytterbium oxide, and 15wt% of potassium fluoride, and the mass ratio of the refining agent to the mixed melt is 0.2:1; and The components and contents of the mixed melt after the static treatment are measured. When the components and contents of the mixed melt after the static treatment meet the standards, the mixed melt after the static treatment is subjected to die casting and aging treatment to obtain a high-toughness and high-thermal-conductivity die-cast aluminum alloy. The aging treatment includes a primary low-temperature electric field aging treatment and a secondary high-temperature aging treatment, wherein the primary low-temperature electric field aging treatment is at a temperature of 50°C, a time of 100 hours, and an electric field strength of 2V / cm; the secondary high-temperature aging treatment is at a temperature of 140°C, and a time of 50 hours. The high-toughness and high-thermal-conductivity die-cast aluminum alloy contains 6% Si by mass, 0.5% Fe by mass, 3% Mg by mass, 0.1% Sr by mass, 0.04% RE by mass, 0.3% Ti by mass, 0.05% B by mass, 1% Zn by mass, 0.05% Cr by mass, 0.01% Te by mass, 0.01% Ag by mass, 0.01% Sb by mass, 0.01% Bi by mass, and 0.01% Nb by mass.

[0075] Embodiment 7 The mold is surface treated to form a 5 mm boron carbide layer on the parting surface of the mold; Heating the recycled aluminum to obtain a recycled aluminum melt; The temperature is adjusted to 780° C., and industrial silicon and steel waste are added to the recycled aluminum melt to obtain a mixed melt; The mixed melt is subjected to a boronization treatment and a first refining treatment, wherein the boronization agent of the boronization treatment is an aluminum-boron alloy, the mass ratio of the aluminum-boron alloy to the mixed melt is 0.001:1, the temperature of the first refining treatment is 750°C, the time is 60 minutes, the refining agent includes 70wt% of potassium chloride, 10wt% of ytterbium oxide, and 20wt% of potassium fluoride, and the mass ratio of the refining agent to the mixed melt is 0.0001:1; The temperature is adjusted to 740°C, and after adding magnesium alloy scrap, Sr, RE, Cr, Zn, and Al-Ti-B alloy to the mixed melt after the first refining treatment, the mixed melt is subjected to a second refining treatment, a slag removal treatment, a degassing treatment, and a standing treatment. After the standing treatment, the surface scum is scraped off, the temperature of the second refining treatment is 740°C, the time is 40 minutes, the refining agent includes 70wt% of potassium chloride, 10wt% of lanthanum oxide, and 20wt% of potassium fluoride, and the mass ratio of the refining agent to the mixed melt is 0.02:1; and The components and contents of the mixed melt after the static treatment are measured. When the components and contents of the mixed melt after the static treatment meet the standards, the mixed melt after the static treatment is subjected to die casting and aging treatment to obtain a high-toughness and high-thermal-conductivity die-cast aluminum alloy. The aging treatment includes a primary low-temperature electric field aging treatment and a secondary high-temperature aging treatment, wherein the primary low-temperature electric field aging treatment is at a temperature of 120°C, a time of 0.1h, and an electric field strength of 20V / cm; the secondary high-temperature aging treatment is at a temperature of 250°C, and a time of 0.1h. The high-toughness and high-thermal-conductivity die-cast aluminum alloy contains 8% Si by mass, 0.4% Fe by mass, 2.5% Mg by mass, 0.05% Sr by mass, 0.02% RE by mass, 0.1% Ti by mass, 0.02% B by mass, 0.5% Zn by mass, 0.05% Cr by mass, 0.02% V by mass, 0.05% Mn by mass, and 0.2% AlTiC by mass.

[0076] Embodiment 8 The mold is surface treated to form a 2 mm boron carbide layer on the parting surface of the mold; Heating the recycled aluminum to obtain a recycled aluminum melt; The temperature is adjusted to 810° C., and industrial silicon and steel waste are added to the recycled aluminum melt to obtain a mixed melt; The mixed melt is subjected to a boronization treatment and a first refining treatment, wherein the boronization agent of the boronization treatment is an aluminum-boron alloy, and the mass ratio of the aluminum-boron alloy to the mixed melt is 0.002:1; the temperature of the first refining treatment is 750°C, the time is 40 minutes, the refining agent is sodium chloride, and the mass ratio of sodium chloride to the mixed melt is 0.0001:1; The temperature is adjusted to 720°C, and after adding magnesium alloy scrap, Sr, RE, Cr, Zn, and Al-Ti-B alloy to the mixed melt after the first refining treatment, the mixed melt is subjected to a second refining treatment, a slag removal treatment, a degassing treatment, and a standing treatment. After the standing treatment, the surface scum is scraped off. The temperature of the second refining treatment is 750°C, the time is 10 minutes, the refining agent is sodium chloride, and the mass ratio of sodium chloride to the mixed melt is 0.01:1; and The components and contents of the mixed melt after the static treatment are measured. When the components and contents of the mixed melt after the static treatment meet the standards, the mixed melt after the static treatment is subjected to die casting and aging treatment to obtain a high-toughness and high-thermal-conductivity die-cast aluminum alloy. The aging treatment includes a primary low-temperature electric field aging treatment and a secondary high-temperature aging treatment, wherein the primary low-temperature electric field aging treatment is at a temperature of 120°C, a time of 1 hour, and an electric field strength of 50V / cm; the secondary high-temperature aging treatment is at a temperature of 140°C, and a time of 50 hours. The high-toughness and high-thermal-conductivity die-cast aluminum alloy contains 6% Si by mass, 0.7% Fe by mass, 3% Mg by mass, 0.02% Sr by mass, 0.05% RE by mass, 0.1% Ti by mass, 0.01% B by mass, 0.3% Zn by mass, 0.1% Cr by mass, 0.01% V by mass, 0.1% Mn by mass, 0.2% AlTiC by mass, 0.2% SiC by mass, and 0.5% BN by mass.

[0077] The components and contents of the aluminum alloys of Examples 1 to 8 are shown in Table 1.

[0078] Table 1 Composition and content of aluminum alloys in Examples 1 to 8 To simplify the description, the examples do not show the contents of all impurity elements.

[0079] Table 2 Performance test results of aluminum alloys of Examples 1 to 8 Table 2 shows that the aluminum alloys of Examples 1 to 8 have good tensile strength, yield strength, elongation and thermal conductivity. After aging treatment, the aluminum alloys of Examples 2 to 8 have a tensile strength of not less than 420 MPa, a yield strength of not less than 335 MPa, an elongation of not less than 10%, and a thermal conductivity of not less than 160 W / mK.

[0080] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for preparing a high-toughness and high-thermal-conductivity die-cast aluminum alloy, comprising the following steps: Heating the recycled aluminum to obtain a recycled aluminum melt; The temperature is adjusted to 740-860° C., and industrial silicon and steel waste are added to the recycled aluminum melt to obtain a mixed melt; performing a boronization treatment and a first refining treatment on the mixed melt; The temperature is adjusted to 710-780° C., magnesium alloy scrap, Sr, RE, Cr, Zn, and Al-Ti-B alloy are added to the mixed melt after the first refining treatment, the mixed melt is subjected to a second refining treatment, and the components and contents in the mixed melt after the second refining treatment are measured; and When the components and contents in the mixed melt after the second refining treatment meet the standards, the mixed melt is die-casted to obtain a high-toughness and high-thermal-conductivity die-cast aluminum alloy, wherein the high-toughness and high-thermal-conductivity die-cast aluminum alloy contains 6-11% Si by mass, 0.05-0.8% Fe by mass, 0.2-3% Mg by mass, 0.001-0.1% Sr by mass, 0-0.2% RE by mass, 0-0.3% Ti by mass, 0-0.05% B by mass, 0-1% Zn by mass, and 0.0001-0.5% Cr by mass.

2. The method for preparing a high-toughness and high-thermal-conductivity die-cast aluminum alloy according to claim 1, characterized in that: The high-toughness and high-thermal-conductivity die-cast aluminum alloy contains 6-11% Si by mass, 0.2-0.8% Fe by mass, 1-3% Mg by mass, 0.001-0.1% Sr by mass, 0.01-0.1% RE by mass, 0.001-0.1% Ti by mass, 0.001-0.05% B by mass, 0.1-0.5% Zn by mass, and 0.001-0.2% Cr by mass.

3. The method for preparing a high-toughness and high-thermal-conductivity die-cast aluminum alloy according to claim 1, characterized in that: The sum of the mass percentage contents of Sr, RE, B, and Cr is less than the mass percentage content of Fe.

4. The method for preparing a high-toughness and high-thermal-conductivity die-cast aluminum alloy according to claim 3, characterized in that: The ratio of the sum of the mass percentage contents of Sr, RE, B, and Cr to the mass percentage content of Fe is 0.01-0.6:

1.

5. The method for preparing a high-toughness and high-thermal-conductivity die-cast aluminum alloy according to claim 1, characterized in that: The method for preparing the high-toughness and high-thermal-conductivity die-cast aluminum alloy also includes the step of adding at least one of Cu, V, Ca, Zr, Te, Ag, Sb, Bi, Nb, SiC, AlTiC, and BN to the recycled aluminum melt, wherein the mass percentage content of Cu is 0.0001-1%, the mass percentage content of V is 0.005-0.2%, the mass percentage content of Ca is 0.0001-0.3%, the mass percentage content of Zr is 0.0001-0.5%, the mass percentage content of Te is 0-0.2%, the mass percentage content of Ag is 0-0.2%, the mass percentage content of Sb is 0-0.5%, the mass percentage content of Bi is 0-0.2%, the mass percentage content of Nb is 0-0.3%, the mass percentage content of SiC is 0-1%, the mass percentage content of TiC is 0-1%, and the mass percentage content of BN is 0-0.5%.

6. The method for preparing a high-toughness and high-thermal-conductivity die-cast aluminum alloy according to any one of claims 1 to 5, characterized in that: Meet at least one of the following conditions: The boronizing agent for the boronizing treatment is potassium fluoroborate and / or aluminum boron alloy; The mass ratio of the boronizing agent to the mixed melt in the boronizing treatment is 0.001-0.005:1; The temperature of the first refining treatment is 740-800°C and the time is 20-60min; The refining agent of the first refining treatment is at least one of chloride salt, fluoride salt, and rare earth; The mass ratio of the refining agent to the mixed melt in the first refining treatment is 0.0001-0.0005:1; The temperature of the second refining treatment is 690-750°C and the time is 10-40min; The refining agent of the second refining treatment includes at least one of chloride salt, fluoride salt, and rare earth; The mass ratio of the refining agent to the mixed melt in the second refining treatment is 0.001-0.2:

1.

7. The method for preparing a high-toughness and high-thermal-conductivity die-cast aluminum alloy according to any one of claims 1 to 5, characterized in that: After the mixed melt is die-casted to obtain an aluminum alloy part, the method for preparing a high-toughness and high-thermal-conductivity die-cast aluminum alloy further comprises the step of performing an aging treatment on the aluminum alloy part, wherein: The aging treatment is performed at a temperature of 150-250°C and a time of 0.05-30h; or The aging treatment includes a primary low-temperature electric field aging treatment and a secondary high-temperature aging treatment, wherein the temperature of the primary low-temperature electric field aging treatment is 50-120°C, the time is 0.1-100h, and the electric field strength is 2-50kV / cm; the temperature of the secondary high-temperature aging treatment is 140-250°C, and the time is 0.1-50h.

8. A high toughness and high thermal conductivity die-cast aluminum alloy, containing Al, characterized in that: The high-toughness and high-thermal-conductivity die-cast aluminum alloy also contains 6-11% Si by mass, 0.05-0.8% Fe by mass, 0.2-3% Mg by mass, 0.001-0.1% Sr by mass, 0-0.2% RE by mass, 0-0.3% Ti by mass, 0-0.05% B by mass, 0-1% Zn by mass, and 0.0001-0.5% Cr by mass.

9. The method for preparing a high-toughness and high-thermal-conductivity die-cast aluminum alloy according to claim 8, characterized in that: The high-toughness and high-thermal-conductivity die-cast aluminum alloy further contains at least one of Cu, V, Ca, Zr, Te, Ag, Sb, Bi, Nb, SiC, AlTiC, and BN, wherein the mass percentage content of Cu is 0.0001-1%, the mass percentage content of V is 0.005-0.2%, the mass percentage content of Ca is 0.0001-0.3%, the mass percentage content of Zr is 0.0001-0.5%, the mass percentage content of Te is 0-0.2%, the mass percentage content of Ag is 0-0.2%, the mass percentage content of Sb is 0-0.5%, the mass percentage content of Bi is 0-0.2%, the mass percentage content of Nb is 0-0.3%, the mass percentage content of SiC is 0-1%, the mass percentage content of TiC is 0-1%, and the mass percentage content of BN is 0-0.5%.

10. A structural member, characterized in that: The material of the structural part is the high-toughness and high-thermal-conductivity die-cast aluminum alloy obtained by the preparation method of the high-toughness and high-thermal-conductivity die-cast aluminum alloy as described in any one of claims 1-7, or the high-toughness and high-thermal-conductivity die-cast aluminum alloy as described in any one of claims 8-9.

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