A die-casting aluminum alloy, preparation method and application

Abstract

The present application provides a die-cast aluminum alloy, a preparation method and an application. By adopting Sb+Y composite modification treatment, online quenching and artificial aging treatment, the mechanical properties and thermal conductivity of the alloy are significantly improved. The prepared die-cast aluminum alloy has a tensile strength of more than 250MPa, a yield strength of more than 110MPa, and a thermal conductivity of more than 180W / m·k, achieving a high level of mechanical properties and thermal conductivity, overcoming the problem of mutual restriction between the two. Therefore, the high thermal conductivity die-cast aluminum alloy provided in the present application has both good thermal conductivity and good mechanical properties, and can be used to manufacture products such as 5G communication base station heat dissipation housings and new energy vehicle heat dissipation parts.

Description

Technical Field

[0001] The present invention relates to the technical field of die-casting aluminum alloys, and in particular to a die-casting aluminum alloy, a preparation method and an application thereof. Background Art

[0002] Al-Si cast aluminum alloys have significant advantages such as high specific strength, good casting performance, small thermal expansion coefficient and low production cost. They are widely used in many fields such as electronic communications, rail transportation, aerospace, and automobiles. The most common Al-Si alloy is ADC12 alloy, which has the advantages of excellent casting fluidity and mechanical processing performance as well as good strength. It is particularly suitable for the die-casting production of complex thin-walled devices such as communication equipment, new energy vehicle heat sinks, and LED lighting equipment. However, with the advent of the 5G communication era, the chip integration of electronic products and communication equipment has gradually increased, and the increase in equipment power has led to an increase in heat generation, which has also increased the heat dissipation per unit volume of the equipment. This has put forward higher requirements on the thermal conductivity of the material to ensure the service life of the product and the stability of its operation.

[0003] Pure aluminum has good thermal conductivity, and its room temperature thermal conductivity is about 237W / (m·K), which is second only to copper (385W / (m·K)) among metal materials. However, the strength of pure aluminum is too low, only 69MPa, which cannot meet the requirements of industrial production applications. Therefore, the strength of pure aluminum is generally improved by alloying, but the addition of alloying elements will significantly reduce the thermal conductivity of the material.

[0004] The ADC12 die-casting alloy, which is currently widely used in the production of communication heat dissipation devices, has a Si content of 9.5-11.5%, and has excellent casting fluidity and good mechanical properties. However, there are a large number of coarse lath-shaped primary silicon and needle-shaped eutectic silicon in the ADC12 alloy structure, which seriously split the Al matrix and significantly reduce the thermal conductivity of the material. Its thermal conductivity is only 96W / (m□K), far less than half of pure aluminum. This has limited the further development and application of Al-Si alloys to a certain extent. Therefore, how to solve the problem of mutual constraints between strengthening aluminum alloys and improving thermal conductivity, and to significantly improve the thermal conductivity of alloys while ensuring the mechanical properties of cast aluminum alloys, has become a key technical problem that urgently needs to be solved. Summary of the invention

[0005] In view of the above problems, the present application aims to provide a die-cast aluminum alloy and a preparation method, which has a simple process, low cost of the prepared aluminum alloy, good thermal conductivity and high mechanical properties, and is suitable for manufacturing 5G communication base station heat dissipation housings or new energy vehicle heat dissipation parts.

[0006] In a first aspect, the present application provides a die-casting aluminum alloy, which comprises the following components by weight percentage: Si 2.0-13.0%, Fe 0.1-1.5%, Mg 0.01-0.1%, Mn≤0.005%, Cu≤0.005%, Ti≤0.005%, Sb 0.1-0.3%, Y 0.1-0.3%, and the balance is Al and unavoidable impurities.

[0007] Optimized, according to the technical solution provided in this embodiment, the aluminum alloy includes the following components by weight percentage: Si 8.0-8.5%, Fe 0.7-0.75%, Mg 0.01-0.05%, Mn≤0.005%, Cu≤0.005%, Ti≤0.005%, Sb 0.1-0.3%, Y 0.1-0.3%, and the balance is Al and unavoidable impurities.

[0008] Among them, according to the technical solution provided in this embodiment, the optimal components of the aluminum alloy by weight percentage include: Si 8.0%, Fe 0.7%, Mg 0.01%, Mn 0.004%, Cu 0.005%, Ti 0.004%, Sb 0.15%, Y0.15%, and the remainder is Al and unavoidable impurities.

[0009] In a second aspect, the present application provides a method for preparing a die-cast aluminum alloy, comprising the following steps:

[0010] Weigh industrial pure aluminum, crystalline silicon, magnesium ingot, aluminum-iron alloy, aluminum-antimony alloy, aluminum-copper alloy, aluminum-manganese alloy, aluminum-yttrium alloy, and aluminum-titanium-boron alloy according to weight percentage;

[0011] Melt industrial pure aluminum and perform the first slag removal to obtain pure aluminum melt;

[0012] Adding crystalline silicon, aluminum-manganese alloy, aluminum-iron alloy, aluminum-copper alloy, and aluminum-yttrium alloy to the pure aluminum melt, and melting the mixture to obtain a first aluminum alloy melt;

[0013] The temperature of the first aluminum alloy melt is adjusted to 720-730° C., and then a magnesium ingot and an aluminum-titanium-boron alloy are added to obtain a second aluminum alloy melt after melting;

[0014] Heating the second aluminum alloy melt to 725-735° C., and then performing a second slag removal on the second aluminum alloy melt;

[0015] The temperature of the second aluminum alloy melt is maintained at 720-730° C., and the second aluminum alloy melt is subjected to a first refining to obtain a third aluminum alloy melt;

[0016] Maintaining the temperature of the third aluminum alloy melt at 720-730° C., and performing a second refining on the third aluminum alloy melt to obtain a fourth aluminum alloy melt;

[0017] The temperature of the fourth aluminum alloy melt is adjusted to 710-720° C., and then an aluminum-antimony alloy is added, and after stirring, degassing, and standing, a fifth aluminum alloy melt is obtained;

[0018] Preheat the mold to 250-300°C;

[0019] Adjusting the fifth aluminum alloy melt to 670-690° C., then injecting the fifth aluminum alloy melt into the mold, and obtaining the first aluminum alloy after solidification;

[0020] Performing online quenching on the first aluminum alloy to obtain a second aluminum alloy;

[0021] The second aluminum alloy is artificially aged to obtain a finished aluminum alloy.

[0022] According to the technical solution provided in this embodiment, the first aluminum alloy is subjected to online quenching to obtain the second aluminum alloy, comprising the following steps:

[0023] The first aluminum alloy is taken out and immediately placed in cooling water, wherein the temperature of the cooling water is 20-30°C.

[0024] According to the technical solution provided in this embodiment, artificial aging treatment is performed on the second aluminum alloy to obtain a finished aluminum alloy, including the following steps:

[0025] The second aluminum alloy is heated to 150-250° C. and then kept at this temperature for 3-5 hours.

[0026] According to the technical solution provided in this embodiment, the second aluminum alloy melt is subjected to a first refining to obtain the third aluminum alloy melt, comprising the following steps:

[0027] Blowing a refining agent into the second aluminum alloy melt;

[0028] Refining time 10-15min;

[0029] After refining, let it stand for 2 to 3 minutes.

[0030] According to the technical solution provided in this embodiment, the third aluminum alloy melt is subjected to a second refining to obtain a fourth aluminum alloy melt, comprising the following steps:

[0031] Blowing a refining agent into the third aluminum alloy melt;

[0032] Refining time 10-15min;

[0033] After refining, let it stand for 2 to 3 minutes.

[0034] According to the technical solution provided in this embodiment, the amount of the refining agent is 1.5-2.5% of the weight of the second aluminum alloy melt.

[0035] According to the technical solution provided in this embodiment, obtaining the first aluminum alloy melt includes the following steps:

[0036] The pure aluminum melt is heated to 750-760° C., and then the crystalline silicon, the aluminum-manganese alloy, the aluminum-iron alloy, the aluminum-copper alloy, and the aluminum-yttrium alloy are added, and then stirred for 25 minutes.

[0037] According to the technical solution provided in this embodiment, the aluminum alloy is used to manufacture the heat dissipation shell of a 5G communication base station or the heat dissipation parts of new energy vehicles.

[0038] In summary, the present application discloses a die-cast aluminum alloy, a preparation method and an application thereof. The beneficial effects produced based on the above scheme are:

[0039] (1) The finished aluminum alloy prepared in this application has a tensile strength of >250MPa, a yield strength of >120MPa, and a thermal conductivity of >190W / m·k. It has good thermal conductivity and maintains good mechanical properties. It is suitable for manufacturing products such as 5G communication base station heat dissipation housings and new energy vehicle heat dissipation parts, meeting their heat dissipation performance requirements;

[0040] (2) When Sb is modified alone, AlSb can not only serve as the core of the eutectic Si phase growth, but also promote the early precipitation of the α(Al) phase, thereby achieving the purpose of inhibiting the growth of the eutectic Si phase, but cannot change the growth direction of the eutectic Si phase; when Y is modified, it can trigger stacking faults to produce twins. The increase in the twin density hinders the growth of the eutectic Si phase along the original direction, and changes the growth direction of the eutectic Si phase; the present application adds two modifiers, Sb and Y, to produce a composite metamorphic effect on the aluminum alloy melt. The two metamorphic mechanisms act on the eutectic Si phase at the same time, so that while it is being refined, its growth direction is also changed. After modification, online quenching and artificial aging, the eutectic Si phase is almost completely transformed into small round particles, and the eutectic Si phase is scattered at the grain boundaries of the α(Al) phase, neither adhering nor maintaining a certain distance, and the number of α(Al) phases increases. Such an organizational structure greatly reduces the hindering effect on electrons, significantly improves the thermal conductivity, and maintains good mechanical properties. In addition, after artificial aging treatment, the cast eutectic Si phase is further transformed into a spherical or ellipsoidal shape, further clearing the passage for electrons to pass through the α phase, thereby further improving the thermal conductivity and mechanical properties, solving the problem of mutual restriction between the two.

[0041] (3) Fe is generally considered a harmful element in aluminum alloys, but it has the effect of reducing the tendency of castings to stick to the mold and improving production efficiency. It also forms an Al-Si-Fe phase, reduces the solid solubility of Si in Al, and eliminates the effect of Si on the thermal conductivity of aluminum alloys to a certain extent. In the present application, the aluminum-iron alloy is added, and while the beneficial effect of Fe is exerted, the needle-shaped or Chinese character-shaped Fe-rich phase is made fine and uniform through the composite modification treatment of Sb and Y, thereby reducing its harm to the thermal conductivity and mechanical properties of aluminum alloys;

[0042] (4) The present application adopts Sb-Y composite modification, which overcomes the problem that the conventional modifier Sr is easy to burn when it is modified alone, and it is easy to cause molten metal to absorb gas, greatly improving the cleanliness of the molten metal, thereby further reducing the influence of pinholes and impurities on obtaining good mechanical properties and thermal conductivity. Moreover, as the smelting progresses, the burnout rate of Sb and Y is low, and the modification effect can be fully exerted for a long time, achieving a long-term modification effect, which overcomes the problem that the conventional modifier Sr has a gradually increasing burnout rate and a low modification effect.

[0043] (5) The present application adopts two modifiers, Sb and Y, which have the characteristics of low burnout rate and low gas absorption, and adopts two refining treatments to significantly improve the cleanliness of the aluminum alloy melt and reduce defects such as pinholes in the aluminum alloy, thereby obtaining better comprehensive performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Other features, objects and advantages of the present application will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings.

[0045] Figure 1 This is a flow chart of the method for preparing die-cast aluminum alloy for this application.

[0046] Figure 2 This is a 200-fold metallographic structure diagram of the finished aluminum alloy of Example 1 of the present application. DETAILED DESCRIPTION

[0047] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant inventions, rather than to limit the inventions. It is also necessary to explain that, for ease of description, only the parts related to the invention are shown in the accompanying drawings. The present application is described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

[0048] Example 1

[0049] A die-casting aluminum alloy comprises the following components by weight percentage: 8.0% Si, 0.7% Fe, 0.01% Mg, 0.004% Mn, 0.005% Cu, 0.004% Ti, 0.15% Sb, 0.15% Y, and the balance is Al and inevitable impurities.

[0050] According to Figure 1 The process flow chart of the die-casting aluminum alloy preparation method shown in the figure, a die-casting aluminum alloy preparation method comprises the following steps:

[0051] According to the above weight percentage, after calculation, weigh industrial pure aluminum, crystalline silicon, magnesium ingot, aluminum-iron alloy, aluminum-antimony alloy, aluminum-copper alloy, aluminum-manganese alloy, aluminum-yttrium alloy, and aluminum-titanium-boron alloy;

[0052] Use a crucible to melt industrial pure aluminum, and after it is completely melted, heat it up to 730°C, perform the first slag removal, and obtain pure aluminum melt;

[0053] Adding the crystalline silicon, the aluminum-manganese alloy, the aluminum-iron alloy, the aluminum-copper alloy, and the aluminum-yttrium alloy into the pure aluminum melt to obtain a first aluminum alloy melt after melting;

[0054] Among them, the pure aluminum melt should be heated to 750-760℃ before adding various alloys. After the addition is completed, it should be stirred for 25 minutes to accelerate the melting and diffusion of the alloy elements.

[0055] Adjusting the temperature of the first aluminum alloy melt to 720-730° C., then adding the magnesium ingot and the aluminum-titanium-boron alloy, and melting them to obtain a second aluminum alloy melt;

[0056] The magnesium ingot and the aluminum-titanium-boron alloy need to be pressed into the first aluminum alloy melt to melt and prevent oxidation from generating impurities.

[0057] The second aluminum alloy melt is heated to 730° C., and then the second aluminum alloy melt is deslagging for the second time; during this period, the composition of the second aluminum alloy melt is tested and the composition of the second aluminum alloy melt is adjusted to a qualified level;

[0058] The temperature of the second aluminum alloy melt is maintained at 720-730° C., and the second aluminum alloy melt is subjected to a first refining to obtain a third aluminum alloy melt;

[0059] The refining agent is blown into the second aluminum alloy melt by a titanium tube for refining, the refining gas is high-purity argon gas, the amount of the refining agent is 1.5-2.5% of the weight of the second aluminum alloy melt, the refining time is 10-15 minutes, and after the refining is completed, it is left to stand for 2-3 minutes, and then the third slag is removed; specifically, the preferred amount of the refining agent is 2% of the weight of the second aluminum alloy melt, and the preferred refining time is 10 minutes;

[0060] Maintaining the temperature of the third aluminum alloy melt at 720-730° C., and performing a second refining on the third aluminum alloy melt to obtain a fourth aluminum alloy melt;

[0061] The refining agent is blown into the third aluminum alloy melt by a titanium tube for refining, the refining gas is high-purity argon, the amount of the refining agent is 1.5-2.5% of the weight of the second aluminum alloy melt, the refining time is 10-15 minutes, and after the refining is completed, it is left to stand for 2-3 minutes, and then the fourth slag is removed; specifically, the preferred amount of the refining agent is 2% of the weight of the second aluminum alloy melt, and the preferred refining time is 10 minutes;

[0062] The temperature of the fourth aluminum alloy melt is adjusted to 710-720° C., and then the aluminum-antimony alloy is added, and after stirring, degassing, and standing, a fifth aluminum alloy melt is obtained;

[0063] Among them, high-purity argon gas is used for degassing for 2 to 3 minutes, and after degassing, it is left to stand for 20 minutes;

[0064] Preheat the mold to 250-300°C;

[0065] Among them, the surface of the mold cavity needs to be cleaned, and thermal conductive paint should be sprayed in the cavity, thermal insulation paint should be sprayed on the flow channel, and thermal insulation paint should be sprayed on the riser;

[0066] Adjusting the fifth aluminum alloy melt to 670-690° C., then injecting the fifth aluminum alloy melt into the mold, and obtaining the first aluminum alloy after solidification;

[0067] Performing online quenching on the first aluminum alloy to obtain a second aluminum alloy;

[0068] After taking out the first aluminum alloy, immediately put it into 20-30°C water to cool it to room temperature, completing the online quenching treatment;

[0069] performing artificial aging treatment on the second aluminum alloy to obtain a finished aluminum alloy;

[0070] The second aluminum alloy is heated to 150-250°C, then kept warm for 3-5 hours, and then naturally cooled to room temperature after being taken out. Specifically, the preferred control parameters are to heat the second aluminum alloy to 200°C, and then keep warm for 4 hours.

[0071] Samples were taken from the finished aluminum alloy and the mechanical properties were tested according to the requirements of GB / T 228.1. Then the thermal conductivity was tested according to the conductivity conversion method. The test results are shown in Table 1.

[0072] Take samples from finished aluminum alloy for metallographic examination, such as Figure 2The figure shows a 200-fold metallographic structure picture. It can be seen from the picture that the matrix structure is mainly composed of fine and diffusely distributed α(Al) phase (white particles) and eutectic Si phase (gray area). The eutectic Si phase is almost completely transformed into fine round particles under the action of Sb+Y composite metamorphism, and the eutectic Si phase is dispersed at the grain boundary of the α(Al) phase, which is neither adhered nor keeps a certain distance, significantly reducing the splitting of the eutectic Si phase to the α(Al) phase, maintaining a high continuity of the α(Al) phase, thereby reducing the resistance of electrons passing through the α(Al) phase, obtaining higher thermal conductivity, and maintaining higher mechanical properties.

[0073] Samples were taken from the finished aluminum alloy to observe the metallographic structure. After testing, the pinhole rate was less than level 1, indicating that after metamorphism and two refining treatments, the aluminum alloy molten liquid had a higher degree of cleanliness.

[0074] Sampling was performed on the finished aluminum alloy for component detection, wherein Sb was 0.148% and Y was 0.149%. There was almost no burnout during the entire smelting process, which fully exerted its metamorphic effect. Since the Sb and Y burnout was extremely low, while exerting a long-term metamorphic effect, the present application can adopt a two-time refining treatment process to remove the gas from the aluminum alloy melt to the greatest extent. Compared with only one refining treatment, the cleanliness of the aluminum alloy melt is significantly improved, defects such as pinholes are reduced, and a guarantee is provided for the aluminum alloy to obtain better comprehensive performance.

[0075] Example 2

[0076] The same points as in Example 1 will not be described in detail, except that:

[0077] A die-casting aluminum alloy comprises the following components by weight percentage: 2.0% Si, 0.1% Fe, 0.01% Mg, 0.002% Mn, 0.003% Cu, 0.005% Ti, 0.1% Sb, 0.3% Y, and the balance is Al and inevitable impurities.

[0078] Example 3

[0079] The same points as in Example 1 will not be described in detail, except that:

[0080] A die-casting aluminum alloy comprises the following components by weight percentage: 13.0% Si, 1.5% Fe, 0.1% Mg, 0.005% Mn, 0.005% Cu, 0.003% Ti, 0.3% Sb, 0.1% Y, and the balance is Al and inevitable impurities.

[0081] Comparative Example 1

[0082] A die-casting aluminum alloy comprises the following components by weight percentage: 8.0% Si, 0.7% Fe, 0.01% Mg, 0.004% Mn, 0.005% Cu, 0.004% Ti, 0.3% Sb, and the balance is Al and inevitable impurities.

[0083] The aluminum alloy component does not contain Y element, and the preparation method thereof comprises the following steps:

[0084] According to the above weight percentages, after calculation, weigh industrial pure aluminum, crystalline silicon, magnesium ingot, aluminum-iron alloy, aluminum-antimony alloy, aluminum-copper alloy, aluminum-manganese alloy, and aluminum-titanium-boron alloy;

[0085] Use a crucible to melt industrial pure aluminum, and after it is completely melted, heat it up to 730°C, perform the first slag removal, and obtain pure aluminum melt;

[0086] Adding the crystalline silicon, the aluminum-manganese alloy, the aluminum-iron alloy, and the aluminum-copper alloy into the pure aluminum melt to obtain a first aluminum alloy melt after melting;

[0087] Among them, the pure aluminum melt should be heated to 750-760℃ before adding various alloys. After the addition is completed, it should be stirred for 25 minutes to accelerate the melting and diffusion of the alloy elements.

[0088] Adjusting the temperature of the first aluminum alloy melt to 720-730° C., then adding the magnesium ingot and the aluminum-titanium-boron alloy, and melting them to obtain a second aluminum alloy melt;

[0089] The magnesium ingot and the aluminum-titanium-boron alloy need to be pressed into the first aluminum alloy melt to melt and prevent oxidation from generating impurities.

[0090] The second aluminum alloy melt is heated to 730° C., and then the second aluminum alloy melt is deslagging for the second time; during this period, the composition of the second aluminum alloy melt is tested and the composition of the second aluminum alloy melt is adjusted to a qualified level;

[0091] The temperature of the second aluminum alloy melt is maintained at 720-730° C., and the second aluminum alloy melt is subjected to a first refining to obtain a third aluminum alloy melt;

[0092] The refining agent is blown into the second aluminum alloy melt through a titanium tube for refining, the refining gas is high-purity argon gas, the amount of the refining agent is 2% of the weight of the second aluminum alloy melt, the refining time is 10 minutes, and after the refining is completed, it is left to stand for 2 to 3 minutes, and then the third slag removal is performed;

[0093] Maintaining the temperature of the third aluminum alloy melt at 720-730° C., and performing a second refining on the third aluminum alloy melt to obtain a fourth aluminum alloy melt;

[0094] The refining agent is blown into the third aluminum alloy melt by a titanium tube for refining, and the amount of the refining agent is 2% of the weight of the second aluminum alloy melt. The refining time is 10 minutes. After the refining is completed, the refining is allowed to stand for 2 to 3 minutes, and then the fourth slag removal is performed.

[0095] The temperature of the fourth aluminum alloy melt is adjusted to 710-720° C., and then the aluminum-antimony alloy is added, and after stirring, degassing, and standing, a fifth aluminum alloy melt is obtained;

[0096] Among them, high-purity argon gas is used for degassing for 2 to 3 minutes, and after degassing, it is left to stand for 20 minutes;

[0097] Preheat the mold to 250-300°C;

[0098] Among them, the surface of the mold cavity needs to be cleaned, and thermal conductive paint should be sprayed in the cavity, thermal insulation paint should be sprayed on the flow channel, and thermal insulation paint should be sprayed on the riser;

[0099] The fifth aluminum alloy melt is adjusted to 670-690° C., and then the fifth aluminum alloy melt is injected into the mold to obtain the first aluminum alloy after solidification.

[0100] Samples were taken from the first aluminum alloy, and the mechanical properties were tested according to the requirements of GB / T 228.1. Then, the thermal conductivity was tested according to the electrical conductivity conversion method. The test results are shown in Table 1.

[0101] Comparative Example 2

[0102] A die-casting aluminum alloy comprises the following components by weight percentage: 8.0% Si, 0.7% Fe, 0.01% Mg, 0.004% Mn, 0.005% Cu, 0.004% Ti, 0.3% Y, and the balance is Al and inevitable impurities.

[0103] The aluminum alloy component does not contain Sb element, and the preparation method thereof is the same as that of Comparative Example 1 and will not be described in detail, except that:

[0104] According to the above weight percentages, after calculation, weigh industrial pure aluminum, crystalline silicon, magnesium ingot, aluminum-iron alloy, aluminum-copper alloy, aluminum-manganese alloy, aluminum-yttrium alloy, and aluminum-titanium-boron alloy;

[0105] The temperature of the fourth aluminum alloy melt is adjusted to 710-720° C., and after stirring, degassing, and standing, a fifth aluminum alloy melt is obtained.

[0106] Comparative Example 3

[0107] A die-casting aluminum alloy comprises the following components by weight percentage: 8.0% Si, 0.7% Fe, 0.01% Mg, 0.004% Mn, 0.005% Cu, 0.004% Ti, 0.15% Sb, 0.15% Y, and the balance is Al and inevitable impurities.

[0108] The preparation method is the same as that of Comparative Example 1 and will not be described in detail.

[0109] Comparative Example 4

[0110] The same as Comparative Example 1 is not repeated here, except that:

[0111] Performing online quenching on the first aluminum alloy to obtain a second aluminum alloy;

[0112] After taking out the first aluminum alloy, it is immediately placed in 20-30° C. water to cool to room temperature, thereby completing the online quenching treatment.

[0113] Samples were taken from the second aluminum alloy, and the mechanical properties were tested according to the requirements of GB / T 228.1. Then, the thermal conductivity was tested according to the electrical conductivity conversion method. The test results are shown in Table 1.

[0114] Comparative Example 5

[0115] The same as Comparative Example 2 is not repeated here, except that:

[0116] Performing online quenching on the first aluminum alloy to obtain a second aluminum alloy;

[0117] After taking out the first aluminum alloy, it is immediately placed in 20-30° C. water to cool to room temperature, thereby completing the online quenching treatment.

[0118] Samples were taken from the second aluminum alloy, and the mechanical properties were tested according to the requirements of GB / T 228.1. Then, the thermal conductivity was tested according to the electrical conductivity conversion method. The test results are shown in Table 1.

[0119] Comparative Example 6

[0120] The same as Comparative Example 3 is not repeated here, except that:

[0121] Performing online quenching on the first aluminum alloy to obtain a second aluminum alloy;

[0122] After taking out the first aluminum alloy, it is immediately placed in 20-30° C. water to cool to room temperature, thereby completing the online quenching treatment.

[0123] Samples were taken from the second aluminum alloy, and the mechanical properties were tested according to the requirements of GB / T 228.1. Then, the thermal conductivity was tested according to the electrical conductivity conversion method. The test results are shown in Table 1.

[0124] Comparative Example 7

[0125] The same as Comparative Example 1 is not repeated here, except that:

[0126] Performing artificial aging treatment on the first aluminum alloy to obtain a finished aluminum alloy;

[0127] The first aluminum alloy is heated to 200° C., then kept warm for 4 hours, and then naturally cooled to room temperature after being taken out.

[0128] Samples were taken from the finished aluminum alloy and the mechanical properties were tested according to the requirements of GB / T 228.1. Then the thermal conductivity was tested according to the conductivity conversion method. The test results are shown in Table 1.

[0129] Comparative Example 8

[0130] The same as Comparative Example 2 is not repeated here, except that:

[0131] Performing artificial aging treatment on the first aluminum alloy to obtain a finished aluminum alloy;

[0132] The first aluminum alloy is heated to 200° C., then kept warm for 4 hours, and then naturally cooled to room temperature after being taken out.

[0133] Samples were taken from the finished aluminum alloy and the mechanical properties were tested according to the requirements of GB / T 228.1. Then the thermal conductivity was tested according to the conductivity conversion method. The test results are shown in Table 1.

[0134] Comparative Example 9

[0135] The same as Comparative Example 3 is not repeated here, except that:

[0136] Performing artificial aging treatment on the first aluminum alloy to obtain a finished aluminum alloy;

[0137] The first aluminum alloy is heated to 200° C., then kept warm for 4 hours, and then naturally cooled to room temperature after being taken out.

[0138] Samples were taken from the finished aluminum alloy and the mechanical properties were tested according to the requirements of GB / T 228.1. Then the thermal conductivity was tested according to the conductivity conversion method. The test results are shown in Table 1.

[0139] Comparative Example 10

[0140] A die-casting aluminum alloy comprises the following components by weight percentage: 8.0% Si, 0.7% Fe, 0.01% Mg, 0.004% Mn, 0.005% Cu, 0.004% Ti, and the balance is Al and inevitable impurities.

[0141] The preparation method thereof is the same as that of Example 1 and will not be described in detail, except that:

[0142] According to the above weight percentages, after calculation, weigh industrial pure aluminum, crystalline silicon, magnesium ingot, aluminum-iron alloy, aluminum-copper alloy, aluminum-manganese alloy, and aluminum-titanium-boron alloy;

[0143] Adding the crystalline silicon, the aluminum-manganese alloy, the aluminum-iron alloy, and the aluminum-copper alloy into the pure aluminum melt to obtain a first aluminum alloy melt after melting;

[0144] The temperature of the fourth aluminum alloy melt is adjusted to 710-720° C., and after stirring, degassing, and standing, a fifth aluminum alloy melt is obtained.

[0145] Comparative Example 11

[0146] A die-casting aluminum alloy comprises the following components by weight percentage: 8.0% Si, 0.7% Fe, 0.01% Mg, 0.004% Mn, 0.005% Cu, 0.004% Ti, 0.3% Sb, and the balance is Al and inevitable impurities.

[0147] The preparation method thereof is the same as that of Example 1 and will not be described in detail, except that:

[0148] According to the above weight percentages, after calculation, weigh industrial pure aluminum, crystalline silicon, magnesium ingot, aluminum-iron alloy, aluminum-antimony alloy, aluminum-copper alloy, aluminum-manganese alloy, and aluminum-titanium-boron alloy;

[0149] The crystalline silicon, the aluminum-manganese alloy, the aluminum-iron alloy, and the aluminum-copper alloy are added to the pure aluminum melt, and a first aluminum alloy melt is obtained after melting.

[0150] Comparative Example 12

[0151] A die-casting aluminum alloy comprises the following components by weight percentage: 8.0% Si, 0.7% Fe, 0.01% Mg, 0.004% Mn, 0.005% Cu, 0.004% Ti, 0.3% Y, and the balance is Al and inevitable impurities.

[0152] The preparation method thereof is the same as that of Example 1 and will not be described in detail, except that:

[0153] According to the above weight percentages, after calculation, weigh industrial pure aluminum, crystalline silicon, magnesium ingot, aluminum-iron alloy, aluminum-copper alloy, aluminum-manganese alloy, aluminum-yttrium alloy, and aluminum-titanium-boron alloy;

[0154] The temperature of the fourth aluminum alloy melt is adjusted to 710-720° C., and after stirring, degassing, and standing, a fifth aluminum alloy melt is obtained.

[0155] Comparative Example 13

[0156] The 6th issue of "Special Casting and Nonferrous Alloys" in 2004 disclosed "The Effect of Holding Time on the Quality of ZL102 Alloy Melt", which explained that the conventional modifier Sr has an increasing burnout rate with the extension of holding time, the modification effect retention is low, and the pinhole rate is at level 2 to 3. It also shows that the conventional modifier Sr is prone to air absorption during the process, which in turn easily leads to defects in the aluminum alloy, making it difficult to meet the performance requirements of products such as 5G communication base station heat dissipation shells and new energy vehicle heat dissipation parts with continuously increasing requirements for thermal conductivity and mechanical properties.

[0157] Table 1 shows the test results of mechanical properties, thermal conductivity and pinhole rate of the die-cast aluminum alloys of Examples 1 to 3 and Comparative Examples 1 to 12.

[0158] Table 1

[0159]

[0160] It can be seen from the above embodiments and comparative examples that the present application provides a die-cast aluminum alloy, which is prepared by Sb+Y composite modification, online quenching and artificial aging treatment, and the tensile strength of the aluminum alloy reaches more than 250MPa, the yield strength reaches more than 110MPa, and the thermal conductivity reaches more than 180W / m·k. The best thermal conductivity is embodiment 1, with a tensile strength of 255MPa, a yield strength of 110MPa, and a thermal conductivity of 197W / m·k, achieving a high level of mechanical properties and thermal conductivity, overcoming the problem of mutual restriction. It can be seen from the comparative examples that Sb+Y composite modification has a low burnout rate, can maintain a long-term modification effect, and is not easy to absorb air. After two refining treatments, the melt can maintain a high cleanliness, achieving the effect of significantly reducing the amount of pinholes and impurities in the aluminum alloy. After online quenching and 200℃ / 4h artificial aging treatment, the mechanical properties and thermal conductivity of the alloy are significantly improved. Therefore, the high thermal conductivity die-cast aluminum alloy provided in this application has both good thermal conductivity and good mechanical properties, and is very suitable for manufacturing products such as 5G communication base station heat dissipation housings and new energy vehicle heat dissipation parts.

[0161] The above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for preparing a die-cast aluminum alloy, characterized in that: The following steps are involved: Melt industrial pure aluminum and perform the first slag removal to obtain pure aluminum melt; Adding crystalline silicon, aluminum-manganese alloy, aluminum-iron alloy, aluminum-copper alloy, and aluminum-yttrium alloy to the pure aluminum melt, and melting the mixture to obtain a first aluminum alloy melt; Adjusting the temperature of the first aluminum alloy melt to 720-730° C., then adding a magnesium ingot and an aluminum-titanium-boron alloy, and melting them to obtain a second aluminum alloy melt; Heating the second aluminum alloy melt to 725-735° C., and then performing a second slag removal on the second aluminum alloy melt; The temperature of the second aluminum alloy melt is maintained at 720-730° C., and the second aluminum alloy melt is subjected to a first refining to obtain a third aluminum alloy melt; The third aluminum alloy melt is maintained at 720-730° C., and the third aluminum alloy melt is subjected to a second refining to obtain a fourth aluminum alloy melt; The temperature of the fourth aluminum alloy melt is adjusted to 710-720° C., and then an aluminum-antimony alloy is added, and after stirring, degassing, and standing, a fifth aluminum alloy melt is obtained; Preheat the mold to 250~300℃; Adjusting the fifth aluminum alloy melt to 670-690° C., then injecting the fifth aluminum alloy melt into the mold, and obtaining the first aluminum alloy after solidification; Performing online quenching on the first aluminum alloy to obtain a second aluminum alloy; performing artificial aging treatment on the second aluminum alloy to obtain a finished aluminum alloy; The aluminum alloy comprises the following components by weight percentage: Si 2.0-13.0%, Fe 0.1-1.5%, Mg 0.01-0.1%, Mn ≤0.005%, Cu ≤0.005%, Ti ≤0.005%, Sb 0.1-0.3%, Y 0.1-0.3%, and the balance is Al and inevitable impurities.

2. The method for preparing a die-cast aluminum alloy according to claim 1, characterized in that: The aluminum alloy comprises the following components by weight percentage: Si 8.0-8.5%, Fe 0.7-0.75%, Mg 0.01-0.05%, Mn ≤0.005%, Cu ≤0.005%, Ti ≤0.005%, Sb 0.1-0.3%, Y 0.1-0.3%, and the balance is Al and inevitable impurities.

3. The method for preparing a die-cast aluminum alloy according to claim 1, characterized in that: Online quenching of the first aluminum alloy to obtain a second aluminum alloy comprises the following steps: The first aluminum alloy is taken out and immediately placed in cooling water, wherein the cooling water temperature is 20-30°C.

4. The method for preparing a die-cast aluminum alloy according to claim 1, characterized in that: Performing artificial aging treatment on the second aluminum alloy to obtain a finished aluminum alloy comprises the following steps: The second aluminum alloy is heated to 150-250° C. and then kept at this temperature for 3-5 hours.

5. The method for preparing a die-cast aluminum alloy according to claim 1, characterized in that: The second aluminum alloy melt is subjected to a first refining to obtain the third aluminum alloy melt, comprising the following steps: Blowing a refining agent into the second aluminum alloy melt; Refining time 10~15min; After refining, let it stand for 2 to 3 minutes.

6. The method for preparing a die-cast aluminum alloy according to claim 1, characterized in that: The third aluminum alloy melt is subjected to a second refining to obtain a fourth aluminum alloy melt, comprising the following steps: Blowing a refining agent into the third aluminum alloy melt; Refining time 10~15min; After refining, let it stand for 2 to 3 minutes.

7. A method for preparing a die-cast aluminum alloy according to claim 5 or 6, characterized in that: The amount of the refining agent is 1.5-2.5% of the weight of the second aluminum alloy melt.

8. The method for preparing a die-cast aluminum alloy according to claim 1, characterized in that: Obtaining the first aluminum alloy melt comprises the following steps: The pure aluminum melt is heated to 750-760° C., and then crystalline silicon, aluminum-manganese alloy, aluminum-iron alloy, aluminum-copper alloy, and aluminum-yttrium alloy are added.

9. The die-cast aluminum alloy obtained by the method for preparing the die-cast aluminum alloy according to claim 1 or 2.

10. The use of the die-casting aluminum alloy according to claim 9, characterized in that: The aluminum alloy is used to manufacture 5G communication base station heat dissipation housings or new energy vehicle heat dissipation parts.

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