Die-casting aluminum alloy with high heat conductivity coefficient as well as preparation method and application of die-casting aluminum alloy

Abstract

The invention discloses a die-casting aluminum alloy with a high heat conductivity coefficient. The die-casting aluminum alloy comprises the following chemical components in percentage by mass: 2.0-20% of La, 2.0-20% of Ce, 0.2-1.2% of Mg, 0.2-0.8% of Cu, 0.2-1.0% of Si, 0.01-0.25% of Nb, 0.05-0.45% of Nd, 0.05-0.45% of Gd, less than or equal to 0.18% of Fe, less than or equal to 0.03% of other inevitable single impurity elements, less than or equal to 0.15% of the total amount of the impurity elements and the balance of aluminum. The rare earth elements La and Ce are main alloy elements, and the content of other alloy elements is optimized, so that the obtained aluminum alloy has high heat conductivity coefficient and mechanical property, and meanwhile, the aluminum alloy has excellent die-casting formability. The obtained die-casting aluminum alloy with the high heat conductivity coefficient is suitable for being used for producing a radiator on high-pressure casting, and the radiator manufactured through the high-pressure casting technology has the high heat conductivity coefficient, the excellent die-casting formability, the good strength and plasticity and the excellent comprehensive performance.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum alloy materials and casting, and specifically relates to a high thermal conductivity die-casting aluminum alloy and a preparation method and application thereof. Background Art

[0002] With the rapid development of modern science and technology, the design of electronic equipment, instruments and modules is increasingly tending towards miniaturization, compactness, high efficiency and lightness. Their power density is getting higher and higher, and huge heat is generated during operation. High-pressure casting is widely used in the manufacture of aluminum alloy heat sinks due to its high production efficiency and the ability to produce thin-walled and complex-shaped workpieces. Aluminum alloy heat sinks made by high-pressure casting have been widely used in chips, high-power LED lamps, communication equipment, electronic equipment and other fields, and also put forward higher development requirements for the thermal conductivity and comprehensive mechanical properties of aluminum alloy materials produced by die-casting technology.

[0003] At present, ADC12 aluminum alloy is widely used in China for the production of die-cast aluminum alloy radiators. This alloy material is a die-cast aluminum alloy material based on Al-Si-Fe alloy. Its advantages are excellent formability and moderate mechanical properties, and its disadvantage is that its thermal conductivity is low. In the ingot state, its thermal conductivity is about 120W / mK. After high-pressure casting, the high cooling rate provided by high-pressure casting increases the supersaturation of alloy elements in the alloy grains, resulting in a low thermal conductivity of the alloy in the high-pressure casting state, usually lower than 110W / mK. In the traditional Al-Si-Fe die-cast aluminum alloy system, if the thermal conductivity is to be improved, its mechanical properties will inevitably be reduced, and it is difficult to achieve the goal of taking both thermal conductivity and mechanical properties into account. Therefore, it is very necessary to develop aluminum alloy materials with high thermal conductivity, good mechanical properties, and excellent die-casting formability. Summary of the invention

[0004] In view of the above-mentioned shortcomings, the present invention discloses a high thermal conductivity die-cast aluminum alloy and its preparation method and application. The rare earth elements La and Ce are used as main alloying elements, and the contents of other alloying elements are optimized so that the obtained aluminum alloy has both high thermal conductivity and mechanical properties. At the same time, it has excellent die-casting formability and is suitable for the production of radiator products with complex shapes.

[0005] The present invention is achieved by adopting the following technical solutions: A high thermal conductivity die-casting aluminum alloy comprising the following chemical components in mass fractions: La: 2.0~20%, Ce: 2.0~20%, Mg: 0.2~1.2%, Cu: 0.2~0.8%, Si: 0.2~1.0%, Nb: 0.01~0.25%, Nd: 0.05~0.45%, Gd: 0.05~0.45%, Fe≤0.18%, other unavoidable single impurity elements ≤0.03%, the total amount of impurity elements ≤0.15%, the balance is aluminum.

[0006] The present invention utilizes La and Ce elements to form Al in aluminum alloy. 11 La3、Al 11 Ce3 intermediate phase, and by controlling the content of La and Ce elements, they will undergo L→Al 11 La3+α-Al, L→Al 11 The eutectic reaction of Ce3+α-Al generates (Al 11 La3+α-Al), (Al 11 Ce3+α-Al) eutectic structure, this kind of intermediate phase is metallic, with certain electrical and thermal conductivity. By using this feature, the high-temperature aluminum alloy melt can have higher fluidity and meet the molding requirements of high-pressure casting production.

[0007] At the same time, the present invention improves the mechanical properties of the alloy material by adding Mg, Cu, Si alloy elements to produce solid solution strengthening, precipitation strengthening and other effects, so as to ensure that the heat sink can meet the strength requirements of various application scenarios after die casting. In addition, adding Nb, Nd, and Gd elements to the aluminum alloy can form Al3Nb, Al3Nd, and Al3Gd intermediate phases. Through microalloying, such intermediate phases with fine dispersion distribution are formed, which, on the one hand, has the effect of refining α-Al grains, and on the other hand, has a great impact on Al 11 La3、Al 11 The Ce3 eutectic structure also has the effect of refining and improving the morphology.

[0008] Furthermore, the high thermal conductivity die-casting aluminum alloy includes the following chemical components in mass fractions: La: 3.0~17%, Ce: 3.0~19%, Mg: 0.3~1.0%, Cu: 0.2~0.6%, Si: 0.2~0.8%, Nb: 0.05~0.18%, Nd: 0.08~0.35%, Gd: 0.08~0.35%, Fe≤0.15%, other unavoidable single impurity elements ≤0.03%, the total amount of impurity elements ≤0.15%, the balance is aluminum.

[0009] Furthermore, the total content of La and Ce elements is not less than 7.0% and not more than 20.0%; the total content of Nd and Gd elements is not less than 0.1% and not more than 0.6%, wherein the ratio of Nd to Gd elements is (3-6):(4-7). By adjusting the total amount of rare earth elements such as La and Ce and their mutual ratio, they can better carry out eutectic reaction and generate suitable eutectic structure, thereby improving the comprehensive performance of aluminum alloy.

[0010] The method for preparing the high thermal conductivity die-casting aluminum alloy comprises the following steps: (1) weighing raw materials in proportion, wherein the raw materials include aluminum ingot, metal lanthanum, metal cerium, magnesium ingot, copper ingot, industrial silicon, aluminum-niobium master alloy, aluminum-neodymium master alloy, and aluminum-gadolinium master alloy; (2) placing an aluminum ingot, an aluminum-niobium master alloy, an aluminum-neodymium master alloy, and an aluminum-gadolinium master alloy in a melting furnace to heat and melt, and performing a first-stage melting at 760 to 860° C. to obtain a melt A. The first-stage melting time is 1 to 5 hours. (3) taking the melt A obtained in step (2) and refining it once at 740-800° C. for 40-70 minutes, and after the refining, standing and slagging to obtain melt B; (4) adding metal lanthanum, metal cerium, magnesium ingot, copper ingot and industrial silicon to the melt B obtained in step (3) and performing second-stage smelting at 740-800° C. to obtain melt C. The second-stage smelting time is 1-3 hours. Sampling is performed from melt C for chemical composition analysis. If there is a deviation in the composition, the raw materials in step (1) are used to adjust the composition and sample again for analysis until all elements reach the expected index, thereby obtaining melt D. (5) The melt D obtained in step (4) is subjected to secondary refining at 700-760° C. for 20-40 minutes. After the secondary refining, samples are taken for analysis. If the composition is still within the expected index range, no further processing is required to proceed to the next step. If the composition deviates, the raw materials in step (1) are used for composition adjustment and sampling is performed again until all elements reach the expected index. (6) The melt D treated in step (5) is released for casting. After double-stage filtration, the melt D enters an automatic casting machine for casting to obtain a high thermal conductivity die-casting aluminum alloy.

[0011] Furthermore, in step (2), during the first stage of smelting, intermittent mechanical stirring is performed, stirring once every 30 minutes, and each stirring time is 10 to 20 minutes; in step (4), during the second stage of smelting, intermittent mechanical stirring is performed, stirring once every 30 minutes, and each stirring time is 5 to 15 minutes. By adjusting the stirring mode, the mixing of the charge during the smelting process is ensured to be uniform, thereby improving the smelting efficiency.

[0012] Furthermore, the primary refining and the secondary refining both use a mixed gas made by mixing high-purity argon, high-purity nitrogen and high-purity chlorine, in which the high-purity argon with a concentration of 99.99% accounts for 90%, the high-purity nitrogen with a concentration of 99.99% accounts for 9%, and the high-purity chlorine with a concentration of 99.99% accounts for 1%.

[0013] Furthermore, in step (6), the first filter plate of the double-stage filtration is 60 mesh, and the second filter plate is 80 mesh; the furnace temperature of the melt D is 680-720°C.

[0014] A die-casting preparation method for a radiator comprises the following steps: S1, placing the high thermal conductivity die-cast aluminum alloy into an aluminum melting furnace, stirring and remelting at 740-800° C. to obtain an alloy melt; S2. The alloy melt obtained in step S1 is refined at 700-740° C. for 10-30 minutes, then allowed to stand and slag removed, and then the alloy melt is kept warm at 680-760° C. for standby use, and the alloy melt is transferred to a cold chamber die-casting machine by a mechanical arm for die-casting, and a radiator die-casting is obtained after cooling.

[0015] Furthermore, the refining process in step S1 uses a mixed gas made by mixing high-purity argon with a concentration of 99.99%, high-purity nitrogen with a concentration of 99.99% and high-purity chlorine with a concentration of 99.99%, wherein the high-purity argon accounts for 90%, the high-purity nitrogen accounts for 9%, and the high-purity chlorine accounts for 1%.

[0016] Furthermore, the die-casting molding in step S2 refers to high-pressure die-casting, during which the first-stage injection speed is 0.1-0.3 m / s, the second-stage injection speed is 0.2-1.0 m / s, the third-stage injection speed is 2.5-8 m / s, the die-casting pressure is 40-80 MPa, and the pressure is maintained for 8-35 seconds.

[0017] The die-casting parts of the rare earth element reinforced aluminum alloy obtained after die-casting can achieve the following performance parameters: thermal conductivity ≥195W / mK, yield strength ≥180MPa, tensile strength ≥260MPa, and elongation after fracture ≥8%.

[0018] Compared with the prior art, this technical solution has the following beneficial effects: The present invention uses rare earth elements La and Ce as main alloying elements, optimizes the content of other alloying elements, and adaptively optimizes and adjusts the smelting, refining and other processes in the preparation process, so that the obtained aluminum alloy material has both high thermal conductivity and excellent mechanical properties, and its die-casting formability is excellent, which is very suitable for the production of radiators with complex shapes, solving the problem that existing aluminum alloy radiators are difficult to achieve both thermal conductivity and mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The metallographic phase diagram is 500 times that of the high thermal conductivity die-cast aluminum alloy prepared in Example 1.

[0020] Figure 2 It is a metallographic image 1000 times larger than that of the high thermal conductivity die-cast aluminum alloy prepared in Example 1.

[0021] Figure 3 This is a scanning electron microscope image of the high thermal conductivity die-cast aluminum alloy die-casting prepared in Example 1. DETAILED DESCRIPTION

[0022] The present invention is further described by the following examples, but is not intended to be limiting of the present invention. Specific experimental conditions and methods not specified in the following examples are conventional methods commonly known to those skilled in the art.

[0023] Embodiment 1: A high thermal conductivity die-casting aluminum alloy comprising the following chemical components in mass fractions: La: 3.1%, Ce: 8.9%, Mg: 0.53%, Cu: 0.42%, Si: 0.61%, Nb: 0.13%, Nd: 0.28%, Gd: 0.19%, Fe: 0.14%, other unavoidable single impurity elements ≤ 0.03%, the total amount of impurity elements ≤ 0.15%, the balance is aluminum.

[0024] The method for preparing the high thermal conductivity die-cast aluminum alloy described in this embodiment comprises the following steps: (1) weighing raw materials in proportion, wherein the raw materials include aluminum ingot, metal lanthanum, metal cerium, magnesium ingot, copper ingot, industrial silicon, aluminum-niobium master alloy, aluminum-neodymium master alloy, and aluminum-gadolinium master alloy; (2) placing an aluminum ingot, an aluminum-niobium master alloy, an aluminum-neodymium master alloy, and an aluminum-gadolinium master alloy in a melting furnace to heat and melt, and performing a first-stage melting at 820° C. to obtain a melt A. The first-stage melting time is 3 hours. During the first-stage melting process, intermittent mechanical stirring is performed, stirring is performed every 30 minutes, and each stirring time is 15 minutes. (3) taking the melt A obtained in step (2) and refining it once at 760° C. for 55 minutes, and after the refining, standing it for 20 minutes and then skimming off the slag to obtain melt B; (4) adding metal lanthanum, metal cerium, magnesium ingot, copper ingot and industrial silicon to the melt B obtained in step (3) and performing second-stage smelting at 800° C. to obtain melt C. The second-stage smelting time is 2 hours. Sampling is performed from melt C for chemical composition analysis. If the composition is deviated, the raw materials in step (1) are used to adjust the composition and sample again for analysis until all elements reach the expected indexes, thereby obtaining melt D. During the second-stage smelting process, intermittent mechanical stirring is performed, stirring is performed every 30 minutes, and each stirring time is 10 minutes. (5) The melt D obtained in step (4) is subjected to secondary refining at 740° C. for 25 minutes. After the secondary refining, the melt is allowed to stand for 20 minutes before slagging. The melt is then sampled and analyzed. If the composition is still within the expected index range, the melt is proceeded to the next step without further treatment. If the composition deviates, the raw materials in step (1) are used to adjust the composition and the melt is sampled and analyzed again until all elements reach the expected index. (6) The melt D treated in step (5) is discharged for casting, and after double-stage filtration, the melt D enters an automatic casting machine for casting to obtain a high thermal conductivity die-casting aluminum alloy; the first-stage filter plate of the double-stage filtration is 60 mesh, and the second-stage filter plate is 80 mesh; the furnace temperature of the melt D is 706°C; The primary refining and the secondary refining both use a mixed gas made by mixing high-purity argon, high-purity nitrogen and high-purity chlorine, in which the high-purity argon with a concentration of 99.99% accounts for 90%, the high-purity nitrogen with a concentration of 99.99% accounts for 9%, and the high-purity chlorine with a concentration of 99.99% accounts for 1%.

[0025] A die-casting preparation method for a radiator comprises the following steps: S1, placing the high thermal conductivity die-casting aluminum alloy into an aluminum melting furnace and stirring and remelting at 780° C. to obtain an alloy melt; S2, taking the alloy melt obtained in step S1 and refining it at 730° C. for 15 minutes, then letting it stand and slagging, then keeping the alloy melt warm at 725° C. for standby use, taking the alloy melt by a mechanical arm and transferring it to a cold chamber die casting machine for die casting, and obtaining a heat sink die casting after cooling; The refining process uses a mixed gas made by mixing high-purity argon with a concentration of 99.99%, high-purity nitrogen with a concentration of 99.99% and high-purity chlorine with a concentration of 99.99%, wherein the high-purity argon accounts for 90%, the high-purity nitrogen accounts for 9%, and the high-purity chlorine accounts for 1%; The die casting refers to high pressure die casting, during which the first stage injection speed is 0.18 m / s, the second stage injection speed is 0.86 m / s, the third stage injection speed is 4.9 m / s, the die casting pressure is 60 MPa, and the pressure is maintained for 15 seconds.

[0026] Embodiment 2: A high thermal conductivity die-casting aluminum alloy comprising the following chemical components in mass fractions: La: 10.2%, Ce: 6.3%, Mg: 0.36%, Cu: 0.27%, Si: 0.74%, Nb: 0.29%, Nd: 0.16%, Gd: 0.25%, Fe: 0.13%, other unavoidable single impurity elements ≤ 0.03%, the total amount of impurity elements ≤ 0.15%, the balance is aluminum.

[0027] The method for preparing the high thermal conductivity die-cast aluminum alloy described in this embodiment comprises the following steps: (1) weighing raw materials in proportion, wherein the raw materials include aluminum ingot, metal lanthanum, metal cerium, magnesium ingot, copper ingot, industrial silicon, aluminum-niobium master alloy, aluminum-neodymium master alloy, and aluminum-gadolinium master alloy; (2) placing an aluminum ingot, an aluminum-niobium master alloy, an aluminum-neodymium master alloy, and an aluminum-gadolinium master alloy in a melting furnace to heat and melt, and performing a first-stage melting at 810° C. to obtain a melt A. The first-stage melting time is 4 hours. During the first-stage melting process, intermittent mechanical stirring is performed, stirring is performed every 30 minutes, and each stirring time is 15 minutes; (3) taking the melt A obtained in step (2) and refining it once at 780° C. for 50 minutes, and after the refining, standing it for 20 minutes and then skimming off the slag to obtain melt B; (4) adding metal lanthanum, metal cerium, magnesium ingot, copper ingot and industrial silicon to the melt B obtained in step (3) and performing second-stage smelting at 780° C. to obtain melt C. The second-stage smelting time is 2 hours. Sampling is performed from melt C for chemical composition analysis. If the composition is deviated, the raw materials in step (1) are used to adjust the composition and sample again for analysis until all elements reach the expected indexes, thereby obtaining melt D. During the second-stage smelting process, intermittent mechanical stirring is performed, stirring is performed every 30 minutes, and each stirring time is 10 minutes. (5) The melt D obtained in step (4) is subjected to secondary refining at 730° C. for 20 minutes. After the secondary refining, the melt is allowed to stand for 20 minutes before slagging. The melt is then sampled and analyzed. If the composition is still within the expected index range, the melt is proceeded to the next step without further treatment. If the composition deviates, the raw materials in step (1) are used to adjust the composition and the melt is sampled and analyzed again until all elements reach the expected index. (6) The melt D treated in step (5) is discharged for casting, and after double-stage filtration, the melt D enters an automatic casting machine for casting to obtain a high thermal conductivity die-casting aluminum alloy; the first-stage filter plate of the double-stage filtration is 60 mesh, and the second-stage filter plate is 80 mesh; the furnace temperature of the melt D is 700°C; The primary refining and the secondary refining both use a mixed gas made by mixing high-purity argon, high-purity nitrogen and high-purity chlorine, in which the high-purity argon with a concentration of 99.99% accounts for 90%, the high-purity nitrogen with a concentration of 99.99% accounts for 9%, and the high-purity chlorine with a concentration of 99.99% accounts for 1%.

[0028] A die-casting preparation method for a radiator comprises the following steps: S1, placing the high thermal conductivity die-casting aluminum alloy into an aluminum melting furnace and stirring and remelting at 785° C. to obtain an alloy melt; S2, refining the alloy melt obtained in step S1 at 720° C. for 12 minutes, then letting it stand and slagging, then keeping the alloy melt warm at 710° C. for standby use, transferring the alloy melt to a cold chamber die casting machine by a mechanical arm for die casting, and obtaining a radiator die casting after cooling; The refining process uses a mixed gas made by mixing high-purity argon with a concentration of 99.99%, high-purity nitrogen with a concentration of 99.99% and high-purity chlorine with a concentration of 99.99%, wherein the high-purity argon accounts for 90%, the high-purity nitrogen accounts for 9%, and the high-purity chlorine accounts for 1%; The die casting refers to high-pressure die casting, during which the first-stage injection speed is 0.18 m / s, the second-stage injection speed is 0.6 m / s, the third-stage injection speed is 6.3 m / s, the die casting pressure is 65 MPa, and the pressure is maintained for 12 seconds.

[0029] Embodiment 3: A high thermal conductivity die-casting aluminum alloy comprising the following chemical components in mass fractions: La: 3.6%, Ce: 14.1%, Mg: 0.41%, Cu: 0.53%, Si: 0.51%, Nb: 0.11%, Nd: 0.12%, Gd: 0.17%, Fe: 0.13%, other unavoidable single impurity elements ≤ 0.03%, the total amount of impurity elements ≤ 0.15%, the balance is aluminum.

[0030] The method for preparing the high thermal conductivity die-cast aluminum alloy described in this embodiment comprises the following steps: (1) weighing raw materials in proportion, wherein the raw materials include aluminum ingot, metal lanthanum, metal cerium, magnesium ingot, copper ingot, industrial silicon, aluminum-niobium master alloy, aluminum-neodymium master alloy, and aluminum-gadolinium master alloy; (2) placing an aluminum ingot, an aluminum-niobium master alloy, an aluminum-neodymium master alloy, and an aluminum-gadolinium master alloy in a melting furnace to heat and melt, and performing a first-stage melting at 800° C. to obtain a melt A. The first-stage melting time is 4 hours. During the first-stage melting process, intermittent mechanical stirring is performed, stirring is performed every 30 minutes, and each stirring time is 15 minutes; (3) taking the melt A obtained in step (2) and refining it once at 760° C. for 50 minutes, and after the refining, standing it for 20 minutes and then skimming off the slag to obtain melt B; (4) adding metal lanthanum, metal cerium, magnesium ingot, copper ingot and industrial silicon to the melt B obtained in step (3) and performing second-stage smelting at 790° C. to obtain melt C. The second-stage smelting time is 3 hours. Sampling is performed from melt C for chemical composition analysis. If the composition is deviated, the raw materials in step (1) are used to adjust the composition and sample again for analysis until all elements reach the expected indexes, thereby obtaining melt D. During the second-stage smelting process, intermittent mechanical stirring is performed, stirring is performed every 30 minutes, and each stirring time is 10 minutes. (5) The melt D obtained in step (4) is subjected to secondary refining at 740°C for 20 minutes. After the secondary refining, the melt is allowed to stand for 20 minutes before slagging. The melt is then sampled and analyzed. If the composition is still within the expected index range, the melt proceeds to the next step without further treatment. If the composition deviates, the raw materials in step (1) are used to adjust the composition and sampled and analyzed again until all elements reach the expected index. (6) The melt D treated in step (5) is discharged for casting, and after double-stage filtration, the melt D enters an automatic casting machine for casting to obtain a high thermal conductivity die-casting aluminum alloy; the first-stage filter plate of the double-stage filtration is 60 mesh, and the second-stage filter plate is 80 mesh; the furnace temperature of the melt D is 705°C; The primary refining and the secondary refining both use a mixed gas made by mixing high-purity argon, high-purity nitrogen and high-purity chlorine, in which the high-purity argon with a concentration of 99.99% accounts for 90%, the high-purity nitrogen with a concentration of 99.99% accounts for 9%, and the high-purity chlorine with a concentration of 99.99% accounts for 1%.

[0031] A die-casting preparation method for a radiator comprises the following steps: S1, placing the high thermal conductivity die-casting aluminum alloy into an aluminum melting furnace and stirring and remelting at 760° C. to obtain an alloy melt; S2, refining the alloy melt obtained in step S1 at 710° C. for 14 minutes, then letting it stand and slagging, then keeping the alloy melt warm at 705° C. for standby use, transferring the alloy melt to a cold chamber die casting machine by a mechanical arm for die casting, and obtaining a radiator die casting after cooling; The refining process uses a mixed gas made by mixing high-purity argon with a concentration of 99.99%, high-purity nitrogen with a concentration of 99.99% and high-purity chlorine with a concentration of 99.99%, wherein the high-purity argon accounts for 90%, the high-purity nitrogen accounts for 9%, and the high-purity chlorine accounts for 1%; The die casting refers to high-pressure die casting, during which the first-stage injection speed is 0.15 m / s, the second-stage injection speed is 0.45 m / s, the third-stage injection speed is 5.5 m / s, the die casting pressure is 75 MPa, and the pressure is maintained for 15 seconds.

[0032] Embodiment 4: A high thermal conductivity die-casting aluminum alloy comprising the following chemical components in mass fractions: La: 12.1%, Ce: 12.7%, Mg: 0.2%, Cu: 0.2%, Si: 0.2%, Nb: 0.012%, Nd: 0.048%, Gd: 0.013%, Fe: 0.16%, other unavoidable single impurity elements ≤ 0.03%, the total amount of impurity elements ≤ 0.15%, the balance is aluminum.

[0033] The method for preparing the high thermal conductivity die-cast aluminum alloy described in this embodiment comprises the following steps: (1) weighing raw materials in proportion, wherein the raw materials include aluminum ingot, metal lanthanum, metal cerium, magnesium ingot, copper ingot, industrial silicon, aluminum-niobium master alloy, aluminum-neodymium master alloy, and aluminum-gadolinium master alloy; (2) placing an aluminum ingot, an aluminum-niobium master alloy, an aluminum-neodymium master alloy, and an aluminum-gadolinium master alloy in a melting furnace to heat and melt, and performing a first-stage melting at 760° C. to obtain a melt A. The first-stage melting time is 4 hours. During the first-stage melting process, intermittent mechanical stirring is performed, stirring is performed every 30 minutes, and each stirring time is 15 minutes. (3) taking the melt A obtained in step (2) and refining it once at 760° C. for 40 minutes, and after the refining, standing it for 20 minutes and then skimming off the slag to obtain melt B; (4) adding metal lanthanum, metal cerium, magnesium ingot, copper ingot and industrial silicon to the melt B obtained in step (3) and performing second-stage smelting at 740° C. to obtain melt C. The second-stage smelting time is 2 hours. Sampling is performed from melt C for chemical composition analysis. If the composition is deviated, the raw materials in step (1) are used to adjust the composition and sample again for analysis until all elements reach the expected indexes, thereby obtaining melt D. During the second-stage smelting process, intermittent mechanical stirring is performed, stirring is performed every 30 minutes, and each stirring time is 10 minutes. (5) The melt D obtained in step (4) is subjected to secondary refining at 730° C. for 20 minutes. After the secondary refining, the melt is allowed to stand for 20 minutes before slagging. The melt is then sampled and analyzed. If the composition is still within the expected index range, the melt is proceeded to the next step without further treatment. If the composition deviates, the raw materials in step (1) are used to adjust the composition and the melt is sampled and analyzed again until all elements reach the expected index. (6) The melt D treated in step (5) is discharged for casting, and after double-stage filtration, the melt D enters an automatic casting machine for casting to obtain a high thermal conductivity die-casting aluminum alloy; the first-stage filter plate of the double-stage filtration is 60 mesh, and the second-stage filter plate is 80 mesh; the furnace temperature of the melt D is 680°C; The primary refining and the secondary refining both use a mixed gas made by mixing high-purity argon, high-purity nitrogen and high-purity chlorine, in which the high-purity argon with a concentration of 99.99% accounts for 90%, the high-purity nitrogen with a concentration of 99.99% accounts for 9%, and the high-purity chlorine with a concentration of 99.99% accounts for 1%.

[0034] A die-casting preparation method for a radiator comprises the following steps: S1, placing the high thermal conductivity die-casting aluminum alloy into an aluminum melting furnace and stirring and remelting at 740° C. to obtain an alloy melt; S2, taking the alloy melt obtained in step S1 and refining it at 700° C. for 30 minutes, then letting it stand and removing the slag, then keeping the alloy melt warm at 680° C. for standby use, using a mechanical arm to transfer the alloy melt to a cold chamber die casting machine for die casting, and obtaining a heat sink die casting after cooling; The refining process uses a mixed gas made by mixing high-purity argon with a concentration of 99.99%, high-purity nitrogen with a concentration of 99.99% and high-purity chlorine with a concentration of 99.99%, wherein the high-purity argon accounts for 90%, the high-purity nitrogen accounts for 9%, and the high-purity chlorine accounts for 1%; The die casting refers to high-pressure die casting, during which the first-stage injection speed is 0.1 m / s, the second-stage injection speed is 0.2 m / s, the third-stage injection speed is 2.5 m / s, the die casting pressure is 40 MPa, and the pressure is maintained for 8 seconds.

[0035] Embodiment 5: A high thermal conductivity die-casting aluminum alloy comprising the following chemical components in mass fractions: La: 2.9%, Ce: 2.5%, Mg: 1.2%, Cu: 0.8%, Si: 1.0%, Nb: 0.25%, Nd: 0.45%, Gd: 0.05%, Fe: 0.12%, other unavoidable single impurity elements ≤ 0.03%, the total amount of impurity elements ≤ 0.15%, the balance is aluminum.

[0036] The method for preparing the high thermal conductivity die-cast aluminum alloy described in this embodiment comprises the following steps: (1) weighing raw materials in proportion, wherein the raw materials include aluminum ingot, metal lanthanum, metal cerium, magnesium ingot, copper ingot, industrial silicon, aluminum-niobium master alloy, aluminum-neodymium master alloy, and aluminum-gadolinium master alloy; (2) An aluminum ingot, an aluminum-niobium master alloy, an aluminum-neodymium master alloy, and an aluminum-gadolinium master alloy are placed in a melting furnace to heat and melt, and a first-stage melting is performed at 860° C. to obtain a melt A. The first-stage melting time is 4 hours. During the first-stage melting process, intermittent mechanical stirring is performed, stirring is performed every 30 minutes, and each stirring time is 15 minutes. (3) taking the melt A obtained in step (2) and refining it once at 780° C. for 70 minutes, and after the refining, standing it for 20 minutes and then skimming off the slag to obtain melt B; (4) adding metal lanthanum, metal cerium, magnesium ingot, copper ingot and industrial silicon to the melt B obtained in step (3) and performing second-stage smelting at 800° C. to obtain melt C. The second-stage smelting time is 3 hours. Sampling is performed from melt C for chemical composition analysis. If the composition is deviated, the raw materials in step (1) are used to adjust the composition and sample again for analysis until all elements reach the expected indexes, thereby obtaining melt D. During the second-stage smelting process, intermittent mechanical stirring is performed, stirring is performed every 30 minutes, and each stirring time is 10 minutes. (5) The melt D obtained in step (4) is subjected to secondary refining at 740°C for 40 minutes. After the secondary refining, the melt is allowed to stand for 20 minutes before slagging and sampling and analysis. If the composition is still within the expected index range, the melt is not processed and proceeds to the next step. If the composition deviates, the raw materials in step (1) are used to adjust the composition and sample analysis is performed again until all elements reach the expected index. (6) The melt D treated in step (5) is discharged for casting, and after double-stage filtration, the melt D enters an automatic casting machine for casting to obtain a high thermal conductivity die-casting aluminum alloy; the first-stage filter plate of the double-stage filtration is 60 mesh, and the second-stage filter plate is 80 mesh; the furnace temperature of the melt D is 720°C; The primary refining and the secondary refining both use a mixed gas made by mixing high-purity argon, high-purity nitrogen and high-purity chlorine, in which the high-purity argon with a concentration of 99.99% accounts for 90%, the high-purity nitrogen with a concentration of 99.99% accounts for 9%, and the high-purity chlorine with a concentration of 99.99% accounts for 1%.

[0037] A die-casting preparation method for a radiator comprises the following steps: S1, placing the high thermal conductivity die-casting aluminum alloy into an aluminum melting furnace and stirring and remelting at 800° C. to obtain an alloy melt; S2, refining the alloy melt obtained in step S1 at 740° C. for 10 minutes, then letting it stand and slagging, then keeping the alloy melt warm at 760° C. for standby use, transferring the alloy melt to a cold chamber die casting machine by a mechanical arm for die casting, and obtaining a heat sink die casting after cooling; The refining process uses a mixed gas made by mixing high-purity argon with a concentration of 99.99%, high-purity nitrogen with a concentration of 99.99% and high-purity chlorine with a concentration of 99.99%, wherein the high-purity argon accounts for 90%, the high-purity nitrogen accounts for 9%, and the high-purity chlorine accounts for 1%; The die casting refers to high pressure die casting, during which the first stage injection speed is 0.3 m / s, the second stage injection speed is 1.0 m / s, the third stage injection speed is 8 m / s, the die casting pressure is 80 MPa, and the pressure is maintained for 35 seconds.

[0038] Comparative Example 1: A radiator produced by ADC12 alloy is used for comparison. The chemical composition of ADC12 alloy is: Si: 10.9%, Mg: 0.23%, Cu: 1.61%, Ti: 0.07%, Zn: 0.67%, Fe: 0.86%, Mn: 0.22%, other inevitable single impurity elements ≤ 0.03%, the total amount of impurity elements ≤ 0.15%, and the balance is aluminum; the ADC12 aluminum alloy is charged into an aluminum melting furnace and heated to 720°C for melting and insulation. After refining, standing and slagging, it is heat-insulated at 660°C for high-pressure casting. The first-stage injection speed is 0.2m / s, the second-stage injection speed is 0.65m / s, and the third-stage injection speed is 7.0m / s. The die-casting pressure is 80MPa, the pressure is maintained for 13 seconds, and the radiator die-casting is obtained after cooling.

[0039] Comparative Example 2: A heat sink produced by Castasil-21 alloy, a high thermal conductivity die-cast aluminum alloy of Rheinmetall of Germany, is used for comparison. The chemical composition of the alloy is: Si: 10.5%, Fe: 0.85%, Mg: 0.23%, Sr: 0.02%. The Castasil-21 aluminum alloy is placed in an aluminum melting furnace and heated to 740°C for melting and heat preservation. After refining, standing, and slagging, it is heat-insulated at 690°C for high-pressure casting. The first-stage injection speed is 0.2m / s, the second-stage injection speed is 0.5m / s, and the third-stage injection speed is 6.0m / s. The die-casting pressure is 70MPa, and the pressure is maintained for 20 seconds. After cooling, the heat sink die-casting is obtained.

[0040] Experimental Example 1: Radiators were produced according to the methods described in Examples 1 to 5 and Comparative Examples 1 to 2, and their performance tests were performed. The specific test contents are as follows: Thermal conductivity and mechanical properties test The thermal diffusivity of the samples was determined by a laser thermal conductivity meter, the specific heat capacity of the samples was determined by a DSC thermal analyzer, and the density of the samples was determined by an analytical balance and a micrometer. The thermal conductivity was obtained by multiplying the thermal diffusivity, specific heat capacity and density. The mechanical properties were determined by a tensile machine. The results are shown in Table 1.

[0041] Table 1 Thermal conductivity and mechanical properties test results of radiator

[0042] It can be seen from Table 1 that the thermal conductivity of the heat sink produced by the present invention is higher than that of the heat sink made of ADC12 and Castasil-21 alloys; the tensile strength and elongation of the heat sink produced by the present invention are also higher than those of the heat sink made of ADC12 and Castasil-21 alloys.

[0043] Experimental Example 2: A high thermal conductivity die-cast aluminum alloy was prepared according to the method described in Examples 1 to 5 and the aluminum alloy materials described in Comparative Examples 1 to 2 were taken for comparison and performance tests were performed. The specific results are shown in Table 2.

[0044] Table 2 Performance test results of die-cast aluminum alloy

[0045] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A high thermal conductivity die-casting aluminum alloy, characterized in that: The chemical components include the following mass fractions: La: 2.0~20%, Ce: 2.0~20%, Mg: 0.2~1.2%, Cu: 0.2~0.8%, Si: 0.2~1.0%, Nb: 0.01~0.25%, Nd: 0.05~0.45%, Gd: 0.05~0.45%, Fe≤0.18%, other unavoidable single impurity elements ≤0.03%, the total amount of impurity elements ≤0.15%, the balance is aluminum.

2. The high thermal conductivity die-cast aluminum alloy according to claim 1, characterized in that: The high thermal conductivity die-casting aluminum alloy comprises the following chemical components in mass fractions: La: 3.0~17%, Ce: 3.0~19%, Mg: 0.3~1.0%, Cu: 0.2~0.6%, Si: 0.2~0.8%, Nb: 0.05~0.18%, Nd: 0.08~0.35%, Gd: 0.08~0.35%, Fe≤0.15%, other unavoidable single impurity elements ≤0.03%, the total amount of impurity elements ≤0.15%, the balance is aluminum.

3. The high thermal conductivity die-cast aluminum alloy according to claim 1, characterized in that: The total content of La and Ce elements shall not be less than 7.0% and not more than 20.0%; the total content of Nd and Gd elements shall not be less than 0.1% and not more than 0.6%, wherein the ratio of Nd to Gd element content is (3-6):(4-7).

4. The method for preparing a high thermal conductivity die-cast aluminum alloy according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) weighing raw materials in proportion, wherein the raw materials include aluminum ingot, metal lanthanum, metal cerium, magnesium ingot, copper ingot, industrial silicon, aluminum-niobium master alloy, aluminum-neodymium master alloy, and aluminum-gadolinium master alloy; (2) placing an aluminum ingot, an aluminum-niobium master alloy, an aluminum-neodymium master alloy, and an aluminum-gadolinium master alloy in a melting furnace to heat and melt, and performing a first-stage melting at 760 to 860° C. to obtain a melt A. The first-stage melting time is 1 to 5 hours. (3) taking the melt A obtained in step (2) and refining it once at 740-800° C. for 40-70 minutes, and after the refining, standing and slagging to obtain melt B; (4) adding metal lanthanum, metal cerium, magnesium ingot, copper ingot and industrial silicon to the melt B obtained in step (3) and performing second-stage smelting at 740-800° C. to obtain melt C. The second-stage smelting time is 1-3 hours. Sampling is performed from melt C for chemical composition analysis. If there is a deviation in the composition, the raw materials in step (1) are used to adjust the composition and sample again for analysis until all elements reach the expected index, thereby obtaining melt D. (5) The melt D obtained in step (4) is subjected to secondary refining at 700-760° C. for 20-40 minutes. After the secondary refining, samples are taken for analysis. If the composition is still within the expected index range, no further processing is required to proceed to the next step. If the composition deviates, the raw materials in step (1) are used for composition adjustment and sampling is performed again until all elements reach the expected index. (6) The melt D treated in step (5) is released for casting. After double-stage filtration, the melt D enters an automatic casting machine for casting to obtain a high thermal conductivity die-casting aluminum alloy.

5. The method for preparing a high thermal conductivity die-cast aluminum alloy according to claim 4, characterized in that: In step (2), during the first stage of smelting, intermittent mechanical stirring is performed, stirring is performed every 30 minutes, and each stirring time is 10 to 20 minutes; in step (4), during the second stage of smelting, intermittent mechanical stirring is performed, stirring is performed every 30 minutes, and each stirring time is 5 to 15 minutes.

6. The method for preparing a high thermal conductivity die-cast aluminum alloy according to claim 4, characterized in that: The primary refining and the secondary refining both use a mixed gas made by mixing high-purity argon, high-purity nitrogen and high-purity chlorine, in which the high-purity argon with a concentration of 99.99% accounts for 90%, the high-purity nitrogen with a concentration of 99.99% accounts for 9%, and the high-purity chlorine with a concentration of 99.99% accounts for 1%.

7. The method for preparing a high thermal conductivity die-cast aluminum alloy according to claim 4, characterized in that: In step (6), the first filter plate of the double-stage filtration is 60 mesh, and the second filter plate is 80 mesh; the furnace temperature of the melt D is 680-720°C.

8. A die-casting method for preparing a radiator, characterized in that: The following steps are involved: S1. The high thermal conductivity die-casting aluminum alloy according to any one of claims 1 to 3 is charged into an aluminum melting furnace and stirred and remelted at 740 to 800° C. to obtain an alloy melt; S2. The alloy melt obtained in step S1 is refined at 700-740° C. for 10-30 minutes, then allowed to stand and slag removed, and then the alloy melt is kept warm at 680-760° C. for standby use, and the alloy melt is transferred to a cold chamber die-casting machine by a mechanical arm for die-casting, and a radiator die-casting is obtained after cooling.

9. The die-casting method for preparing a heat sink according to claim 8, characterized in that: The refining process in step S1 uses a mixed gas made by mixing high-purity argon with a concentration of 99.99%, high-purity nitrogen with a concentration of 99.99% and high-purity chlorine with a concentration of 99.99%, wherein the high-purity argon accounts for 90%, the high-purity nitrogen accounts for 9%, and the high-purity chlorine accounts for 1%.

10. The die-casting method for preparing a heat sink according to claim 8, characterized in that: The die casting in step S2 refers to high pressure die casting, during which the first stage injection speed is 0.1-0.3 m / s, the second stage injection speed is 0.2-1.0 m / s, the third stage injection speed is 2.5-8 m / s, the die casting pressure is 40-80 MPa, and the pressure is maintained for 8-35 seconds.

Images