High-thermal-conductivity aluminum alloy and preparation method thereof

Abstract

The invention relates to a high-thermal-conductivity aluminum alloy and a preparation method thereof. The high-thermal-conductivity aluminum alloy comprises the following elements of, by mass, 5.5%-6.5% of Si, 0.4%-0.8% of Fe, 0.05%-0.3% of Mg, 0.02%-0.04% of Sr, 0.005%-0.015% of B, 0.002%-0.008% of Be and the balance Al. On the basis of balancing the flowing property, the mechanical property and the heat-conducting property, B and Be elements are creatively added, and an external field treatment mode is combined, so that a fine spherical crystal structure is obtained, and the microstructure uniformity, the flowing property of the slurry and the heat-conducting property are synergistically improved. Meanwhile, a two-stage aging process is creatively introduced, so that the heat-conducting property is further improved. Compared with the prior art, the prepared aluminum alloy material is more uniform in microstructure after external field treatment, and meanwhile, the B-containing phase and the two-stage aging process are introduced, so that the heat-conducting property of the alloy is remarkably improved.

Description

Technical Field

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

[0002] The development of the communications industry from 4G to 5G has resulted in a 2.5-3.5-fold increase in base station power. The increase in power has led to a surge in heat generation, and existing aluminum alloys can no longer meet the needs of 5G high-power radiator shells. Since the thermal conductivity of pure aluminum is 237W / (m·K), the addition of alloying elements further reduces the thermal conductivity. Therefore, the thermal conductivity of cast aluminum alloys is generally lower than 200W / (m·K). Currently, commercial Al-Si-based high thermal conductivity materials are mainly Al-8Si, with a thermal conductivity of 140-160W / (m·K), which can meet the heat dissipation and die-casting formability requirements of 4G heat dissipation shells. The large radiator shell material for 5G communications is mainly based on alloy systems with higher Si content. Among them, patent CN115948682A discloses a high thermal conductivity aluminum alloy material for large heat dissipation cavities of 5G communications and a rheological die-casting molding method thereof. The thermal conductivity of the prepared material reaches 193W / (m·K). However, it still cannot meet the higher power requirements of small heat sinks in special 5G application scenarios. Therefore, it is still necessary to further develop materials with higher thermal conductivity based on existing materials to meet the application of specific small thin-walled heat sinks. Summary of the invention

[0003] In order to solve the above problems in the prior art, the present invention provides a high thermal conductivity aluminum alloy and a preparation method thereof.

[0004] In order to achieve the above object, the main technical solutions adopted by the present invention include:

[0005] A high thermal conductivity aluminum alloy, wherein the weight percentages of the components are as follows: Si 5.5-6.5%, Fe 0.4-0.8%, Mg 0.05-0.3%, Sr 0.02-0.04%, B 0.005-0.015%, Be 0.002-0.008%, the content of each impurity element is less than 0.005%, the total impurity element content is less than 0.05%, and the balance is Al.

[0006] A method for preparing a high thermal conductivity aluminum alloy comprises the following steps:

[0007] S1 melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be and ordinary aluminum ingots are prepared according to the target composition, heated to 720-730℃, cooled to 680-700℃ after complete melting, and then pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0008] Preferably, the temperature of adding pure magnesium in step S1 is controlled at 690° C., which can minimize the burning loss of magnesium element and achieve precise control of Mg content.

[0009] S2 refining: heat to 740-760℃, add 0.1-0.3% mass fraction of RE refining agent, stir for 3-7 minutes to make it react completely with the melt, and let it stand for 10-15 minutes;

[0010] Preferably, in step S2, the refining agent is added at a temperature of 750°C, and the RE refining agent is added at a mass percentage of 0.2%, and stirred for 5 minutes to obtain a better refining and degassing effect. The mass percentage of 0.2% is calculated according to the mass of the aluminum melt obtained in step S1.

[0011] S3 modification: After refining, the temperature is lowered to 710-720℃ and then Sr element is added in the form of Al-10Sr master alloy. Then, it is stirred for 3-5 minutes to make it completely melted and then subjected to rotary spraying of inert gas. After standing, a high-purity melt is obtained or cast into an alloy ingot for standby use;

[0012] S4 external field treatment: After remelting the high purity melt or alloy ingot, keep it at 690-710℃. The alloy melt is treated under the action of external field before die casting to further improve the flow and filling ability of the alloy.

[0013] Preferably, in step S4, melt treatment under the action of an external field is performed before die-casting, mainly including one or two of mechanical stirring, electromagnetic stirring, ultrasonic treatment and gas disturbance.

[0014] S5 die casting: After the external field treatment, the melt temperature is maintained at 610-630℃, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged to further improve the thermal conductivity.

[0015] Preferably, in step S5, the thermal conductivity performance of the casting obtained by the double-stage aging process (250°C-2h+350°C-0.5h) is significantly higher than that of the single-stage aging process (250°C-2h).

[0016] The beneficial effects of the present invention are as follows: on the basis of balancing the flow properties, mechanical properties and thermal conductivity, the invention creatively adds B and Be elements and combines external field treatment to obtain a fine spherical crystal structure, thereby achieving a synergistic improvement in microstructure uniformity, slurry flow properties and thermal conductivity. At the same time, a two-stage aging process is creatively introduced to further improve thermal conductivity. Compared with the prior art, the aluminum alloy material prepared by the present invention has a more uniform microstructure after external field treatment, and at the same time introduces a B-containing phase and a two-stage aging process, which significantly improves the thermal conductivity of the alloy. The preparation method is simple, has good process stability, and has a high degree of process controllability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 is a microscopic photograph of a casting prepared from the alloy of Example 1 of the present invention;

[0019] Figure 2 This is the influence of the change of Si element content on thermal conductivity in the present invention;

[0020] Figure 3 This is the influence of the change of Mg element content on thermal conductivity in the present invention;

[0021] Figure 4 This is the influence of the change of Fe element content on thermal conductivity in the present invention;

[0022] Figure 5 This is a comparison of the ingot structure photographs before Sr is added during the smelting process of Example 2 of the present invention;

[0023] Figure 6 This is a comparison of the ingot structure photographs after Sr was added during the smelting process in Example 2 of the present invention;

[0024] Figure 7 It is a microstructure diagram without external field in comparative example 1 of the present invention;

[0025] Figure 8 It is a microstructure diagram with an external field in Example 3 of the present invention;

[0026] Fig. 9 It is the tensile property curve of the typical alloy in Example 2 of the present invention. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] Embodiment 1:

[0029] The chemical composition (mass percentage) of the high thermal conductivity die-casting aluminum alloy material of this embodiment is: 5.5% Si, 0.1 Mg, 0.4% Fe, 0.04% Sr, 0.01% B, 0.005% Be, other inevitable impurities are less than 0.005%, and the rest is Al.

[0030] The aluminum alloy material preparation method involved in this embodiment is:

[0031] (1) Melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be and ordinary aluminum ingots are prepared according to the target composition, heated to 720°C, cooled to 690°C after complete melting, and then pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0032] (2) Refining: Heat to 750°C, add 0.1% by mass of RE refining agent, stir for 5 minutes to allow it to react completely with the melt, and let stand for 15 minutes;

[0033] (3) Modification: After refining, the temperature is lowered to 710°C and Sr element is added in the form of Al-10Sr master alloy. The mixture is then stirred for 5 minutes to completely melt and then subjected to rotary inert gas injection. After standing, a high-purity melt is obtained.

[0034] (4) Field treatment: After remelting the high purity melt, keep it at 690℃. The alloy melt is treated under mechanical stirring before die casting to further improve the alloy's flow and filling ability.

[0035] (5) Die casting: After mechanical stirring, the melt temperature is maintained at 610°C, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged at 250°C-2h+350°C-0.5h.

[0036] The tensile properties and thermal conductivity test results of the die-cast aluminum alloy obtained in this Example 1 are shown in Table 2.

[0037] Embodiment 2:

[0038] The chemical composition (mass percentage) of the high thermal conductivity die-casting aluminum alloy material of this embodiment is: 6% Si, 0.1 Mg, 0.4% Fe, 0.04% Sr, 0.01% B, 0.005% Be, other inevitable impurities are less than 0.005%, and the rest is Al.

[0039] The aluminum alloy material preparation method involved in this embodiment is:

[0040] (1) Melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be and ordinary aluminum ingots are prepared according to the target composition, heated to 720°C, cooled to 690°C after complete melting, and then pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0041] (2) Refining: Heat to 750°C, add 0.1% by mass of RE refining agent, stir for 5 minutes to allow it to react completely with the melt, and let stand for 15 minutes;

[0042] (3) Modification: After refining, the temperature is lowered to 710°C and Sr element is added in the form of Al-10Sr master alloy. The alloy is then stirred for 5 minutes to completely melt and then subjected to rotary inert gas injection. After standing, a high-purity melt is obtained for standby use.

[0043] (4) Field treatment: After remelting the high purity melt, keep it at 690℃. The alloy melt is treated under mechanical stirring before die casting to further improve the alloy's flow and filling ability.

[0044] (5) Die casting: After mechanical stirring, the melt temperature is maintained at 610°C, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged at 250°C-2h+350°C-0.5h.

[0045] The tensile properties and thermal conductivity test results of the die-cast aluminum alloy obtained in this Example 2 are shown in Table 2.

[0046] Embodiment 3:

[0047] The chemical composition (mass percentage) of the high thermal conductivity die-casting aluminum alloy material of this embodiment is: 6.5% Si, 0.1 Mg, 0.4% Fe, 0.04% Sr, 0.01% B, 0.005% Be, other inevitable impurities are less than 0.005%, and the rest is Al.

[0048] The aluminum alloy material preparation method involved in this embodiment is:

[0049] (1) Melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be, ordinary aluminum ingots, and pure magnesium ingots are prepared according to the target composition, heated to 720°C, and after being completely melted, cooled to 690°C, and pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0050] (2) Refining: Heat to 750°C, add 0.1% by mass of RE refining agent, stir for 5 minutes to allow it to react completely with the melt, and let stand for 15 minutes;

[0051] (3) Modification: After refining, the temperature is lowered to 710°C and Sr element is added in the form of Al-10Sr master alloy. The alloy is then stirred for 5 minutes to completely melt and then subjected to rotary spraying of inert gas. After standing, a high purity melt is obtained for standby use.

[0052] (4) Field treatment: After remelting the high purity melt, keep it at 690℃. The alloy melt is subjected to electromagnetic stirring before die casting to further improve the alloy's flow and filling ability.

[0053] (5) Die casting: After electromagnetic stirring, the melt temperature is maintained at 610°C, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged at 250°C-2h+350°C-0.5h.

[0054] The tensile properties and thermal conductivity test results of the die-cast aluminum alloy obtained in this Example 3 are shown in Table 2.

[0055] Embodiment 4:

[0056] The chemical composition (mass percentage) of the high thermal conductivity die-casting aluminum alloy material of this embodiment is: 6.5% Si, 0.05% Mg, 0.6% Fe, 0.02% Sr, 0.010% B, 0.005% Be, other inevitable impurities are less than 0.005%, and the rest is Al.

[0057] The aluminum alloy material preparation method involved in this embodiment is:

[0058] (1) Melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be and ordinary aluminum ingots are prepared according to the target composition, heated to 725°C, cooled to 690°C after complete melting, and then pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0059] (2) Refining: Heat to 740°C, add 0.1% by mass of RE refining agent, stir for 5 minutes to allow it to react completely with the melt, and let stand for 15 minutes;

[0060] (3) Modification: After refining, the temperature is lowered to 715°C and Sr element is added in the form of Al-10Sr master alloy. The alloy is then stirred for 5 minutes to completely melt and then subjected to rotary inert gas injection. After standing, a high-purity melt is obtained for standby use.

[0061] (4) Field treatment: After remelting the high-purity melt, keep it at 700°C. The alloy melt is treated under mechanical stirring before die casting to further improve the alloy's flow and filling ability.

[0062] (5) Die casting: After mechanical stirring, the melt temperature is maintained at 620°C, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged at 250°C-2h+350°C-0.5h.

[0063] The tensile properties and thermal conductivity test results of the die-cast aluminum alloy obtained in this Example 4 are shown in Table 2.

[0064] Embodiment 5:

[0065] The chemical composition (mass percentage) of the high thermal conductivity die-casting aluminum alloy material of this embodiment is: 6.5% Si, 0.15% Mg, 0.6% Fe, 0.02% Sr, 0.010% B, 0.005% Be, other inevitable impurities are less than 0.005%, and the rest is Al.

[0066] The aluminum alloy material preparation method involved in this embodiment is:

[0067] (1) Melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be and ordinary aluminum ingots are prepared according to the target composition, heated to 725°C, cooled to 690°C after complete melting, and then pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0068] (2) Refining: Heat to 740°C, add 0.1% by mass of RE refining agent, stir for 5 minutes to allow it to react completely with the melt, and let stand for 15 minutes;

[0069] (3) Modification: After refining, the temperature is lowered to 715°C and Sr element is added in the form of Al-10Sr master alloy. The alloy is then stirred for 5 minutes to completely melt and then subjected to rotary inert gas injection. After standing, a high-purity melt is obtained for standby use.

[0070] (4) Field treatment: After remelting the high-purity melt, keep it at 700°C. The alloy melt is treated under mechanical stirring before die casting to further improve the alloy's flow and filling ability.

[0071] (5) Die casting: After mechanical stirring, the melt temperature is maintained at 620°C, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged at 250°C-2h+350°C-0.5h.

[0072] The tensile properties and thermal conductivity test results of the die-cast aluminum alloy obtained in this Example 5 are shown in Table 2.

[0073] Embodiment 6:

[0074] The chemical composition (mass percentage) of the high thermal conductivity die-casting aluminum alloy material of this embodiment is: 6.5% Si, 0.30 Mg, 0.6% Fe, 0.02% Sr, 0.010% B, 0.005% Be, other inevitable impurities are less than 0.005%, and the rest is Al.

[0075] The aluminum alloy material preparation method involved in this embodiment is:

[0076] (1) Melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be and ordinary aluminum ingots are prepared according to the target composition, heated to 725°C, cooled to 690°C after complete melting, and then pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0077] (2) Refining: Heat to 740°C, add 0.1% by mass of RE refining agent, stir for 5 minutes to allow it to react completely with the melt, and let stand for 15 minutes;

[0078] (3) Modification: After refining, the temperature is lowered to 715°C and Sr element is added in the form of Al-10Sr master alloy. The alloy is then stirred for 5 minutes to completely melt and then subjected to rotary inert gas injection. After standing, a high-purity melt is obtained for standby use.

[0079] (4) Field treatment: After remelting the high-purity melt, keep it at 700°C. The alloy melt is treated under mechanical stirring before die casting to further improve the alloy's flow and filling ability.

[0080] (5) Die casting: After mechanical stirring, the melt temperature is maintained at 620°C, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged at 250°C-2h+350°C-0.5h.

[0081] The tensile properties and thermal conductivity test results of the die-cast aluminum alloy obtained in this Example 6 are shown in Table 2.

[0082] According to Examples 4-6, the Mg content has a great influence on the strength and thermal conductivity of the alloy. When the Mg content is lower than 0.05%, the tensile strength is low and cannot meet the strength requirements of small radiators. Further increasing the Mg content, although the strength is improved, the thermal conductivity tends to decrease and cannot meet the requirements of high thermal conductivity.

[0083] Embodiment 7:

[0084] The chemical composition (mass percentage) of the high thermal conductivity die-casting aluminum alloy material of this embodiment is: 6.0% Si, 0.15% Mg, 0.4% Fe, 0.02% Sr, 0.010% B, 0.005% Be, other inevitable impurities are less than 0.005%, and the rest is Al.

[0085] The aluminum alloy material preparation method involved in this embodiment is:

[0086] (1) Melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be and ordinary aluminum ingots are prepared according to the target composition, heated to 730°C, cooled to 680°C after complete melting, and then pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0087] (2) Refining: Heat to 760°C, add 0.1% by mass of RE refining agent, stir for 5 minutes to allow it to react completely with the melt, and let stand for 15 minutes;

[0088] (3) Modification: After refining, the temperature is lowered to 720°C and Sr element is added in the form of Al-10Sr master alloy. The alloy is then stirred for 5 minutes to completely melt and then subjected to rotary inert gas injection. After standing, a high-purity melt is obtained for standby use.

[0089] (4) Field treatment: After remelting the high purity melt, keep it at 710℃. The alloy melt is treated under mechanical stirring before die casting to further improve the alloy's flow and filling ability.

[0090] (5) Die casting: After mechanical stirring, the melt temperature is maintained at 630°C, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged at 250°C-2h+350°C-0.5h.

[0091] The tensile properties and thermal conductivity test results of the die-cast aluminum alloy obtained in this Example 7 are shown in Table 2.

[0092] Embodiment 8:

[0093] The chemical composition (mass percentage) of the high thermal conductivity die-casting aluminum alloy material of this embodiment is: 6.0% Si, 0.15% Mg, 0.6% Fe, 0.02% Sr, 0.010% B, 0.005% Be, other inevitable impurities are less than 0.005%, and the rest is Al.

[0094] The aluminum alloy material preparation method involved in this embodiment is:

[0095] (1) Melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be and ordinary aluminum ingots are prepared according to the target composition, heated to 730°C, cooled to 680°C after complete melting, and then pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0096] (2) Refining: Heat to 760°C, add 0.1% by mass of RE refining agent, stir for 5 minutes to allow it to react completely with the melt, and let stand for 15 minutes;

[0097] (3) Modification: After refining, the temperature is lowered to 720°C and Sr element is added in the form of Al-10Sr master alloy. The alloy is then stirred for 5 minutes to completely melt and then subjected to rotary inert gas injection. After standing, a high-purity melt is obtained for standby use.

[0098] (4) Field treatment: After remelting the high purity melt, keep it at 710℃. The alloy melt is treated under mechanical stirring before die casting to further improve the alloy's flow and filling ability.

[0099] (5) Die casting: After mechanical stirring, the melt temperature is maintained at 630°C, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged at 250°C-2h+350°C-0.5h.

[0100] The tensile properties and thermal conductivity test results of the die-cast aluminum alloy obtained in this Example 8 are shown in Table 2.

[0101] Embodiment 9:

[0102] The chemical composition (mass percentage) of the high thermal conductivity die-casting aluminum alloy material of this embodiment is: 6.0% Si, 0.15% Mg, 0.8% Fe, 0.02% Sr, 0.010% B, 0.005% Be, other inevitable impurities are less than 0.005%, and the rest is Al.

[0103] The aluminum alloy material preparation method involved in this embodiment is:

[0104] (1) Melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be and ordinary aluminum ingots are prepared according to the target composition, heated to 730°C, cooled to 680°C after complete melting, and then pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0105] (2) Refining: Heat to 760°C, add 0.1% by mass of RE refining agent, stir for 5 minutes to allow it to react completely with the melt, and let stand for 15 minutes;

[0106] (3) Modification: After refining, the temperature is lowered to 720°C and Sr element is added in the form of Al-10Sr master alloy. The alloy is then stirred for 5 minutes to completely melt and then subjected to rotary inert gas injection. After standing, a high-purity melt is obtained for standby use.

[0107] (4) Field treatment: After remelting the high purity melt, keep it at 710℃. The alloy melt is treated under mechanical stirring before die casting to further improve the alloy's flow and filling ability.

[0108] (5) Die casting: After mechanical stirring, the melt temperature is maintained at 630°C, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged at 250°C-2h+350°C-0.5h.

[0109] The tensile properties and thermal conductivity test results of the die-cast aluminum alloy obtained in this Example 9 are shown in Table 2.

[0110] As shown in Examples 7-9, the increase in Fe content has a greater impact on the elongation of the alloy, and the elongation of the alloy decreases significantly. When it is lower than 0.4%, the alloy tends to stick to the mold and the thin-walled product cannot be demolded. When it is higher than 0.8%, the elongation deteriorates seriously, which easily leads to substandard mechanical properties. The effect on thermal conductivity is relatively weak.

[0111] Embodiment 10:

[0112] The chemical composition (mass percentage) of the high thermal conductivity die-casting aluminum alloy material of this embodiment is: 6.0% Si, 0.15% Mg, 0.8% Fe, 0.03% Sr, 0.010% B, 0.005% Be, other inevitable impurities are less than 0.005%, and the rest is Al.

[0113] The aluminum alloy material preparation method involved in this embodiment is:

[0114] (1) Melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be and ordinary aluminum ingots are prepared according to the target composition, heated to 725°C, cooled to 690°C after complete melting, and then pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0115] (2) Refining: Heat to 750°C, add 0.1% by mass of RE refining agent, stir for 5 minutes to allow it to react completely with the melt, and let stand for 15 minutes;

[0116] (3) Modification: After refining, the temperature is lowered to 715°C and Sr element is added in the form of Al-10Sr master alloy. The alloy is then stirred for 5 minutes to completely melt and then subjected to rotary inert gas injection. After standing, a high-purity melt is obtained for standby use.

[0117] (4) External field treatment: The high purity melt is kept at 695°C, and the alloy melt is treated under electromagnetic stirring before die casting to further improve the alloy's flow and filling ability;

[0118] (5) Die casting: After electromagnetic stirring, the melt temperature is maintained at 620°C, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged at 250°C-2h+350°C-0.5h.

[0119] The tensile properties and thermal conductivity test results of the die-cast aluminum alloy obtained in this Example 10 are shown in Table 2.

[0120] Embodiment 11:

[0121] The chemical composition (mass percentage) of the high thermal conductivity die-casting aluminum alloy material of this embodiment is: 6.0% Si, 0.15% Mg, 0.8% Fe, 0.04% Sr, 0.010% B, 0.005% Be, other inevitable impurities are less than 0.005%, and the rest is Al.

[0122] The aluminum alloy material preparation method involved in this embodiment is:

[0123] (1) Melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be and ordinary aluminum ingots are prepared according to the target composition, heated to 725°C, cooled to 690°C after complete melting, and then pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0124] (2) Refining: Heat to 750°C, add 0.1% by mass of RE refining agent, stir for 5 minutes to allow it to react completely with the melt, and let stand for 15 minutes;

[0125] (3) Modification: After refining, the temperature is lowered to 715°C and Sr element is added in the form of Al-10Sr master alloy. The alloy is then stirred for 5 minutes to completely melt and then subjected to rotary inert gas injection. After standing, a high-purity melt is obtained for standby use.

[0126] (4) External field treatment: The high purity melt is kept at 695°C, and the alloy melt is treated under electromagnetic stirring before die casting to further improve the alloy's flow and filling ability;

[0127] (5) Die casting: After electromagnetic stirring, the melt temperature is maintained at 620°C, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged at 250°C-2h+350°C-0.5h.

[0128] The tensile properties and thermal conductivity test results of the die-cast aluminum alloy obtained in this Example 11 are shown in Table 2.

[0129] Referring to Examples 10-11, the increase in Sr content improves the elongation and thermal conductivity of the alloy by transforming the needle-like or lamellar eutectic Si into a fibrous structure. However, excessive Sr addition (>0.04%) easily leads to gas absorption during the smelting process, increases the gas content, and causes a decrease in thermal conductivity, which is not conducive to process stability control; when the Sr content is lower than 0.02%, it is easy to cause the Sr content to weaken the modification effect on the eutectic Si, and thus fail to achieve effective modification and refinement.

[0130] Embodiment 12:

[0131] The chemical composition (mass percentage) of the high thermal conductivity die-casting aluminum alloy material of this embodiment is: 5.5% Si, 0.3Mg, 0.6% Fe, 0.04% Sr, 0.005% B, 0.002% Be, other inevitable impurities are less than 0.005%, and the rest is Al.

[0132] The aluminum alloy material preparation method involved in this embodiment is:

[0133] (1) Melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be and ordinary aluminum ingots are prepared according to the target composition, heated to 720°C, cooled to 690°C after complete melting, and then pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0134] (2) Refining: Heat to 750°C, add 0.1% by mass of RE refining agent, stir for 5 minutes to allow it to react completely with the melt, and let stand for 15 minutes;

[0135] (3) Modification: After refining, the temperature is lowered to 720°C and Sr element is added in the form of Al-10Sr master alloy. The alloy is then stirred for 5 minutes to completely melt and then subjected to rotary inert gas injection. After standing, a high-purity melt is obtained for standby use.

[0136] (4) External field treatment: The high-purity melt is kept at 700°C, and the alloy melt is subjected to melt treatment under electromagnetic stirring before die casting to further improve the alloy's flow and filling ability;

[0137] (5) Die casting: After electromagnetic stirring, the melt temperature is maintained at 620°C, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged at 250°C-2h+350°C-0.5h.

[0138] The tensile properties and thermal conductivity test results of the die-cast aluminum alloy obtained in this Example 12 are shown in Table 2.

[0139] Embodiment 13:

[0140] The chemical composition (mass percentage) of the high thermal conductivity die-casting aluminum alloy material of this embodiment is: 5.5% Si, 0.3Mg, 0.6% Fe, 0.04% Sr, 0.010% B, 0.002% Be, other inevitable impurities are less than 0.005%, and the rest is Al.

[0141] The aluminum alloy material preparation method involved in this embodiment is:

[0142] (1) Melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be and ordinary aluminum ingots are prepared according to the target composition, heated to 720°C, cooled to 690°C after complete melting, and then pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0143] (2) Refining: Heat to 750°C, add 0.1% by mass of RE refining agent, stir for 5 minutes to allow it to react completely with the melt, and let stand for 15 minutes;

[0144] (3) Modification: After refining, the temperature is lowered to 720°C and Sr element is added in the form of Al-10Sr master alloy. The alloy is then stirred for 5 minutes to completely melt and then subjected to rotary inert gas injection. After standing, a high-purity melt is obtained for standby use.

[0145] (4) External field treatment: The high-purity melt is kept at 700°C, and the alloy melt is subjected to melt treatment under electromagnetic stirring before die casting to further improve the alloy's flow and filling ability;

[0146] (5) Die casting: After electromagnetic stirring, the melt temperature is maintained at 620°C, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged at 250°C-2h+350°C-0.5h.

[0147] The tensile properties and thermal conductivity test results of the die-cast aluminum alloy obtained in this Example 13 are shown in Table 2.

[0148] Embodiment 14:

[0149] The chemical composition (mass percentage) of the high thermal conductivity die-casting aluminum alloy material of this embodiment is: 5.5% Si, 0.3Mg, 0.6% Fe, 0.04% Sr, 0.015% B, 0.002% Be, other inevitable impurities are less than 0.005%, and the rest is Al.

[0150] The aluminum alloy material preparation method involved in this embodiment is:

[0151] (1) Melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be and ordinary aluminum ingots are prepared according to the target composition, heated to 720°C, cooled to 690°C after complete melting, and then pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0152] (2) Refining: Heat to 750°C, add 0.1% by mass of RE refining agent, stir for 5 minutes to allow it to react completely with the melt, and let stand for 15 minutes;

[0153] (3) Modification: After refining, the temperature is lowered to 720°C and Sr element is added in the form of Al-10Sr master alloy. The alloy is then stirred for 5 minutes to completely melt and then subjected to rotary inert gas injection. After standing, a high-purity melt is obtained for standby use.

[0154] (4) External field treatment: The high-purity melt is kept at 700°C, and the alloy melt is subjected to melt treatment under electromagnetic stirring before die casting to further improve the alloy's flow and filling ability;

[0155] (5) Die casting: After electromagnetic stirring, the melt temperature is maintained at 620°C, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged at 250°C-2h+350°C-0.5h.

[0156] The tensile properties and thermal conductivity test results of the die-cast aluminum alloy obtained in this Example 14 are shown in Table 2.

[0157] Referring to Examples 12-14, the B content increases through interaction with Si. Due to the thin-walled characteristics of small heat sinks, the B element can significantly refine the eutectic Si phase under rapid cooling conditions. In alloys with Sr composite additions, the eutectic Si phase can be more effectively improved, thereby improving the elongation and thermal conductivity.

[0158] Embodiment 15:

[0159] The chemical composition (mass percentage) of the high thermal conductivity die-casting aluminum alloy material of this embodiment is: 5.5% Si, 0.3Mg, 0.6% Fe, 0.03% Sr, 0.01% B, 0.002% Be, other inevitable impurities are less than 0.005%, and the rest is Al.

[0160] The aluminum alloy material preparation method involved in this embodiment is:

[0161] (1) Melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be and ordinary aluminum ingots are prepared according to the target composition, heated to 720°C, cooled to 690°C after complete melting, and then pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0162] (2) Refining: Heat to 750°C, add 0.1% by mass of RE refining agent, stir for 5 minutes to allow it to react completely with the melt, and let stand for 15 minutes;

[0163] (3) Modification: After refining, the temperature is lowered to 720°C and Sr element is added in the form of Al-10Sr master alloy. The alloy is then stirred for 5 minutes to completely melt and then subjected to rotary inert gas injection. After standing, a high-purity melt is obtained for standby use.

[0164] (4) External field treatment: The high-purity melt is kept at 700°C, and the alloy melt is subjected to melt treatment under electromagnetic stirring before die casting to further improve the alloy's flow and filling ability;

[0165] (5) Die casting: After electromagnetic stirring, the melt temperature is maintained at 620°C, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged at 250°C-2h+350°C-0.5h.

[0166] The tensile properties and thermal conductivity test results of the die-cast aluminum alloy obtained in this Example 15 are shown in Table 2.

[0167] Embodiment 16:

[0168] The chemical composition (mass percentage) of the high thermal conductivity die-casting aluminum alloy material of this embodiment is: 5.5% Si, 0.3Mg, 0.6% Fe, 0.03% Sr, 0.010% B, 0.005% Be, other inevitable impurities are less than 0.005%, and the rest is Al.

[0169] The aluminum alloy material preparation method involved in this embodiment is:

[0170] (1) Melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be and ordinary aluminum ingots are prepared according to the target composition, heated to 720°C, cooled to 690°C after complete melting, and then pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0171] (2) Refining: Heat to 750°C, add 0.1% by mass of RE refining agent, stir for 5 minutes to allow it to react completely with the melt, and let stand for 15 minutes;

[0172] (3) Modification: After refining, the temperature is lowered to 720°C and Sr element is added in the form of Al-10Sr master alloy. The alloy is then stirred for 5 minutes to completely melt and then subjected to rotary inert gas injection. After standing, a high purity melt is obtained and is ready for use.

[0173] (4) Field treatment: The high-purity melt is kept at 700°C, and the alloy melt is treated under mechanical stirring before die casting to further improve the alloy's flow and filling ability;

[0174] (5) Die casting: After mechanical stirring, the melt temperature is maintained at 620°C, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged at 250°C-2h+350°C-0.5h.

[0175] The tensile properties and thermal conductivity test results of the die-cast aluminum alloy obtained in this Example 16 are shown in Table 2.

[0176] Embodiment 17:

[0177] The chemical composition (mass percentage) of the high thermal conductivity die-casting aluminum alloy material of this embodiment is: 5.5% Si, 0.3Mg, 0.6% Fe, 0.03% Sr, 0.01% B, 0.008% Be, other inevitable impurities are less than 0.005%, and the rest is Al.

[0178] The aluminum alloy material preparation method involved in this embodiment is:

[0179] (1) Melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be and ordinary aluminum ingots are prepared according to the target composition, heated to 720°C, cooled to 690°C after complete melting, and then pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0180] (2) Refining: Heat to 750°C, add 0.1% by mass of RE refining agent, stir for 5 minutes to allow it to react completely with the melt, and let stand for 15 minutes;

[0181] (3) Modification: After refining, the temperature is lowered to 720°C and Sr element is added in the form of Al-10Sr master alloy. The alloy is then stirred for 5 minutes to completely melt and then subjected to rotary inert gas injection. After standing, a high-purity melt is obtained for standby use.

[0182] (4) Field treatment: The high-purity melt is kept at 700°C, and the alloy melt is treated under mechanical stirring before die casting to further improve the alloy's flow and filling ability;

[0183] (5) Die casting: After mechanical stirring, the melt temperature is maintained at 620°C, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged at 250°C-2h+350°C-0.5h.

[0184] The tensile properties and thermal conductivity test results of the die-cast aluminum alloy obtained in this Example 17 are shown in Table 2.

[0185] Referring to Examples 15-17, the increase in Be content is mainly due to the formation of an oxide film on the surface of the melt, which prevents the melt from reacting with air, thereby significantly reducing the gas content in the melt, thereby improving the purity of the melt, thereby increasing the thermal conductivity of the finished product.

[0186] Comparative Example 1:

[0187] The chemical composition (mass percentage) of the high thermal conductivity die-casting aluminum alloy material of this embodiment is: 6.5% Si, 0.1 Mg, 0.4% Fe, 0.04% Sr, 0.01% B, 0.005% Be, other inevitable impurities are less than 0.005%, and the rest is Al.

[0188] The aluminum alloy material preparation method involved in this embodiment is:

[0189] (1) Melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be and ordinary aluminum ingots are prepared according to the target composition, heated to 720°C, cooled to 690°C after complete melting, and then pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0190] (2) Refining: Heat to 750°C, add 0.1% by mass of RE refining agent, stir for 5 minutes to allow it to react completely with the melt, and let stand for 15 minutes;

[0191] (3) Modification: After refining, the temperature is lowered to 710°C and Sr element is added in the form of Al-10Sr master alloy. The alloy is then stirred for 5 minutes to completely melt and then subjected to rotary spraying of inert gas. After standing, a high purity melt is obtained for standby use.

[0192] (4) Die casting: The high purity melt is kept at 690℃, then transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged at 250℃-2h+350℃-0.5h.

[0193] The tensile properties and thermal conductivity test results of the die-cast aluminum alloy obtained in this comparative example 1 are shown in Table 2, and the microstructure comparison diagram is shown in Figure 4 . It can be seen that after adding the external field treatment of electromagnetic stirring, the white α-Al phase transforms from dendrites without external field treatment to spherical crystals, and the structure becomes finer and more uniform, which improves the flow and filling resistance. Thereby significantly reducing casting defects. The thermal conductivity of the alloy is very sensitive to defects. Therefore, after external field treatment, casting defects can be significantly reduced, thereby improving thermal conductivity. The elongation of comparative example 1 in Table 2 is poor, mainly because the lack of external field treatment leads to more air entrainment during the filling process, and even the subsequent heat treatment cannot reach a thermal conductivity of 200W / mK.

[0194] Comparative Example 2:

[0195] The chemical composition (mass percentage) of the high thermal conductivity die-casting aluminum alloy material of this embodiment is: 5.5% Si, 0.3Mg, 0.6% Fe, 0.04% Sr, 0.015% B, 0.002% Be, other inevitable impurities are less than 0.005%, and the rest is Al.

[0196] The aluminum alloy material preparation method involved in this embodiment is:

[0197] (1) Melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be and ordinary aluminum ingots are prepared according to the target composition, heated to 720°C, cooled to 690°C after complete melting, and then pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0198] (2) Refining: Heat to 750°C, add 0.1% by mass of RE refining agent, stir for 5 minutes to allow it to react completely with the melt, and let stand for 15 minutes;

[0199] (3) Modification: After refining, the temperature is lowered to 710°C and Sr element is added in the form of Al-10Sr master alloy, followed by stirring for 5 minutes to make it completely melted and then subjected to rotary spraying of inert gas treatment. After standing, a high-purity melt is obtained or cast into an alloy ingot for standby use;

[0200] (4) External field treatment: After remelting the high-purity melt or alloy ingot, keep it at 690°C. The alloy melt is treated under the action of an external field before die casting to further improve the flow and filling ability of the alloy;

[0201] (5) Die casting: After the external treatment, the melt temperature is maintained at 610°C, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged at 250°C-0.5h.

[0202] The thermal conductivity test results of the die-cast aluminum alloy obtained in this comparative example 2 are shown in Table 2.

[0203] Comparative Example 3:

[0204] The chemical composition (mass percentage) of the high thermal conductivity die-casting aluminum alloy material of this embodiment is: 5.5% Si, 0.3Mg, 0.6% Fe, 0.04% Sr, 0.015% B, 0.002% Be, other inevitable impurities are less than 0.005%, and the rest is Al.

[0205] The aluminum alloy material preparation method involved in this embodiment is:

[0206] (1) Melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be and ordinary aluminum ingots are prepared according to the target composition, heated to 720°C, cooled to 690°C after complete melting, and then pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0207] (2) Refining: Heat to 750°C, add 0.1% by mass of RE refining agent, stir for 5 minutes to allow it to react completely with the melt, and let stand for 15 minutes;

[0208] (3) Modification: After refining, the temperature is lowered to 710°C and Sr element is added in the form of Al-10Sr master alloy. The alloy is then stirred for 5 minutes to completely melt and then subjected to rotary inert gas injection. After standing, a high-purity melt is obtained for standby use.

[0209] (4) Field treatment: The high-purity melt is kept at 690°C, and the alloy melt is treated under mechanical stirring before die casting to further improve the alloy's flow and filling ability;

[0210] (5) Die casting: After mechanical stirring, the melt temperature is maintained at 610°C, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged at 250°C for 2h.

[0211] The thermal conductivity test results of the die-cast aluminum alloy obtained in this comparative example 3 are shown in Table 2.

[0212] Comparative Example 4:

[0213] The chemical composition (mass percentage) of the high thermal conductivity die-casting aluminum alloy material of this embodiment is: 5.5% Si, 0.3Mg, 0.6% Fe, 0.04% Sr, 0.015% B, 0.002% Be, other inevitable impurities are less than 0.005%, and the rest is Al.

[0214] The aluminum alloy material preparation method involved in this embodiment is:

[0215] (1) Melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be and ordinary aluminum ingots are prepared according to the target composition, heated to 720°C, cooled to 690°C after complete melting, and then pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0216] (2) Refining: Heat to 750°C, add 0.1% by mass of RE refining agent, stir for 5 minutes to allow it to react completely with the melt, and let stand for 15 minutes;

[0217] (3) Modification: After refining, the temperature is lowered to 710°C and Sr element is added in the form of Al-10Sr master alloy. The alloy is then stirred for 5 minutes to completely melt and then subjected to rotary inert gas injection. After standing, a high-purity melt is obtained for standby use.

[0218] (4) External field treatment: The high purity melt is kept at 690°C, and the alloy melt is treated under the action of an external field before die casting to further improve the alloy's flow and filling ability;

[0219] (5) Die casting: After field treatment, the melt temperature is maintained at 610°C, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged at 250°C-0.5h+350°C-0.25h.

[0220] The thermal conductivity test results of the die-cast aluminum alloy obtained in this comparative example 4 are shown in Table 2.

[0221] Comparative Example 5:

[0222] The chemical composition (mass percentage) of the high thermal conductivity die-casting aluminum alloy material of this embodiment is: 5.5% Si, 0.3Mg, 0.6% Fe, 0.04% Sr, 0.015% B, 0.002% Be, other inevitable impurities are less than 0.005%, and the rest is Al.

[0223] The aluminum alloy material preparation method involved in this embodiment is:

[0224] (1) Melting: Al-20Si, Al-20Fe, Al-3B, Al-3Be and ordinary aluminum ingots are prepared according to the target composition, heated to 720°C, cooled to 690°C after complete melting, and then pure Mg is quickly pressed into the melt through a bell jar and kept warm for 30 minutes;

[0225] (2) Refining: Heat to 750°C, add 0.1% by mass of RE refining agent, stir for 5 minutes to allow it to react completely with the melt, and let stand for 15 minutes;

[0226] (3) Modification: After refining, the temperature is lowered to 710°C and Sr element is added in the form of Al-10Sr master alloy, followed by stirring for 5 minutes to make it completely melted and then subjected to rotary spraying of inert gas treatment. After standing, a high-purity melt is obtained or cast into an alloy ingot for standby use;

[0227] (4) External field treatment: After remelting the high-purity melt or alloy ingot, keep it at 690°C. The alloy melt is treated under the action of an external field before die casting to further improve the flow and filling ability of the alloy;

[0228] (5) Die casting: After field treatment, the melt temperature is maintained at 610°C, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, the aluminum alloy casting is obtained. The aluminum alloy casting is artificially aged at 250°C-0.5h+350°C-1h.

[0229] The thermal conductivity test results of the die-cast aluminum alloy obtained in this comparative example 5 are shown in Table 2.

[0230] The process differences between Example 14 and Comparative Examples 2-5 are selected for comparison.

[0231]

[0232]

[0233] The purpose of the double-stage aging treatment is to completely precipitate the atoms dissolved in the aluminum matrix at a low temperature of 250°C. At this time, the α-Al phase is relatively pure and easier to conduct electricity. However, the nanophase is relatively small and dispersed at this temperature. Further increasing the temperature to 350°C can further coarsen the nanophase and dissolve it back, reducing the scattering effect of the dispersed nanophase on electrons, phonons, etc. that affect thermal conductivity, thereby improving thermal conductivity. Although high-temperature aging will sacrifice some strength, it can ensure higher thermal conductivity.

[0234] Table 1 Chemical composition of Examples 1-17 and Comparative Examples 1-5 (wt.%)

[0235]

[0236]

[0237] Table 2 Test results of tensile properties and thermal conductivity of die-cast aluminum alloys obtained in Examples 1 to 17 of the present invention and Comparative Examples 1 to 5

[0238]

[0239]

[0240] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention's specification and drawings, or directly or indirectly applied in related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A high thermal conductivity aluminum alloy, characterized in that: The steel comprises the following elements in mass percentage: Si 5.5-6.5%, Fe 0.4-0.8%, Mg 0.05-0.3%, Sr 0.02-0.04%, B 0.005-0.015%, Be 0.002-0.008%, and the balance is Al.

2. The high thermal conductivity aluminum alloy according to claim 1, characterized in that: It also contains unavoidable impurity elements, each of which contains less than 0.005% of the total impurity elements and less than 0.05%.

3. A method for preparing a high thermal conductivity aluminum alloy as claimed in any one of claims 1 to 2, characterized in that: The following steps are involved: S1: Melting: aluminum silicon, aluminum iron, aluminum boron, aluminum beryllium master alloy and ordinary aluminum ingot are formulated according to the target composition, heated to 720-730℃, cooled to 680-700℃ after complete melting, and then pure Mg element is added and kept warm for 30 minutes; S2: Refining, heating to 740-760°C, adding 0.1-0.3% by mass of RE refining agent, stirring for 3-7 minutes to allow it to react completely with the melt, and standing for 10-15 minutes; S3: Modification: After refining, the temperature is lowered to 710-720℃, and then Sr element is added in the form of Al-10Sr master alloy, followed by stirring for 3-5 minutes to make it completely melted, and then rotating and spraying inert gas treatment is performed. After standing, a high-purity melt is obtained or cast into an alloy ingot for standby use; S4: External field treatment: After remelting the high purity melt or alloy ingot, keep it at 690-710℃. The alloy melt is treated under the action of external field before die casting to further improve the flow and filling ability of the alloy. S5: Die casting. After field treatment, the melt temperature is maintained at 610-630°C, and then the melt is transferred to the barrel of the die casting machine for die casting. Finally, aluminum alloy castings are obtained. The aluminum alloy castings are artificially aged to further improve thermal conductivity.

4. The method for preparing a high thermal conductivity aluminum alloy according to claim 3, characterized in that: In step S1, the aluminum-silicon master alloy is Al-20Si; the aluminum-iron master alloy is Al-20Fe; the aluminum-boron master alloy is Al-3B; and the aluminum-beryllium master alloy is Al-3Be.

5. The method for preparing a high thermal conductivity aluminum alloy according to claim 3, characterized in that: In the step S1, the temperature of adding pure magnesium is controlled at 690° C., which can minimize the burning loss of magnesium element and achieve accurate control of Mg content.

6. The method for preparing a high thermal conductivity aluminum alloy according to claim 3, characterized in that: In the step S2, the adding temperature of the refining agent is 750° C., and the RE refining agent is added at a mass percentage of 0.2%, and stirring is performed for 5 minutes.

7. The method for preparing a high thermal conductivity aluminum alloy according to claim 3, characterized in that: The melt processing method under the external field described in step S4 is one or more of mechanical stirring, electromagnetic stirring, ultrasonic processing or gas disturbance.

8. The method for preparing a high thermal conductivity aluminum alloy according to claim 3, characterized in that: The artificial aging treatment in step S5 is a double-stage aging treatment of 250° C. for 0.5-2 h and 350° C. for 0.25-1 h, and after the aging heat treatment, the mixture is naturally cooled to room temperature in the air.

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