Ultrahigh-heat-conductivity integrated die-casting aluminum alloy and preparation process thereof

Abstract

The invention discloses an ultrahigh heat conduction integrated die-casting aluminum alloy and a preparation process thereof, and belongs to the technical field of aluminum alloy material preparation. The preparation process comprises the following steps: burdening according to a specific ratio, strictly controlling the impurity content, carrying out low-oxygen smelting under the protection of argon, and controlling the oxygen content of a melt to be less than or equal to 0.003%; refining is conducted for 10-15 minutes under the condition that the power ranges from 600 W to 800 W and the melt temperature ranges from 720 DEG C to 740 DEG C under argon covering; after refining, standing for 10-20 minutes, and then slagging off; mold filling is conducted at the mold filling pressure of 30-60 MPa and the low speed of 0.3-0.5 m / s, and the mold cooling speed after mold filling is larger than or equal to 50 DEG C / s; and the die casting is subjected to forced air cooling after being subjected to heat preservation at 440-460 DEG C for 1-2 hours. The total amount of Ti and Zr and the content of B in ingredients meet a specific proportion, and part of elements are added in the form of intermediate alloy. The aluminum alloy has excellent thermal conductivity and mechanical property, is suitable for preparation of high-end heat dissipation components, and is high in practicability and remarkable in industrial application value.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy material preparation technology, specifically to an ultra-high thermal conductivity integrated die-cast aluminum alloy and its preparation process. Background Technology

[0002] With the rapid development of the new energy vehicle industry and the widespread adoption of 5G communication technology, the performance requirements for high-end heat dissipation components are becoming increasingly stringent. In the field of new energy vehicles, motors generate a large amount of heat during operation. If this heat cannot be dissipated in time, it will seriously affect the motor's efficiency, lifespan, and safety. In the field of 5G communication, the high power of base station equipment leads to a significant increase in heat dissipation pressure, and heat dissipation efficiency directly determines communication quality and equipment stability. Aluminum alloys, with their advantages of low density, high specific strength, excellent thermal conductivity, and die-casting capability, have become the preferred material for manufacturing these high-end heat dissipation components. In particular, integrated die-cast aluminum alloys can achieve one-time molding of complex structural components, effectively reducing assembly processes and production costs, while improving the structural integrity and mechanical reliability of components. This has become a research hotspot and development trend in the field of aluminum alloy materials.

[0003] For high-end integrated die-cast aluminum alloys used in heat dissipation, thermal conductivity is one of the core performance indicators. At the same time, excellent mechanical properties and good die-casting performance must also be considered to meet the requirements of manufacturing and using complex heat dissipation components. Currently, existing integrated die-cast aluminum alloys are mainly based on Al-Si alloys, with mechanical properties controlled by adding alloying elements such as Mg, Cu, and Ti. However, there are shortcomings in the synergistic optimization of thermal conductivity and mechanical properties.

[0004] In the smelting stage, existing technologies mostly employ conventional atmospheric smelting or simple inert gas-protected smelting, making it difficult to effectively control the oxygen and impurity element content in the melt. This results in the formation of numerous oxide inclusions in the melt, which hinder heat transfer and significantly reduce the thermal conductivity of the aluminum alloy. In the refining stage, traditional refining methods struggle to achieve deep purification of the melt, affecting both thermal conductivity and reducing the alloy's tensile strength and elongation. In the die-casting stage, existing processes often employ high filling speeds, easily leading to unstable melt filling and defects such as gas entrapment and oxidation. Furthermore, improper cooling rate control can result in coarse alloy grains, further reducing the synergy between thermal conductivity and mechanical properties. Moreover, existing technologies lack a systematic approach to alloy composition design, failing to fully consider the synergistic effects of trace elements on grain refinement and second-phase morphology optimization, and neglecting to strictly control the content of unavoidable impurities, making it difficult to achieve breakthrough improvements in the alloy's thermal conductivity and mechanical properties.

[0005] Meanwhile, the thermal expansion coefficient of existing integrated die-cast aluminum alloys is not well-matched with high-end heat dissipation components, making them prone to thermal stress during temperature changes. This can lead to component deformation and cracking, affecting reliability. To address these issues, engineers in related fields have attempted to improve the overall performance of integrated die-cast aluminum alloys by adjusting alloy composition and optimizing manufacturing processes, but have yet to find an effective solution that balances ultra-high thermal conductivity, excellent mechanical properties, and good formability.

[0006] In summary, existing integrated die-cast aluminum alloys suffer from numerous shortcomings in terms of rational composition design, precise manufacturing process, and synergistic performance optimization, making it difficult to meet the urgent needs of new energy vehicles, 5G communications, and other fields for ultra-high thermal conductivity and high strength integrated die-cast aluminum alloys. Therefore, developing an ultra-high thermal conductivity integrated die-cast aluminum alloy and its manufacturing process that can achieve synergistic optimization of thermal conductivity and mechanical properties and possess stable and reliable manufacturing technology is of significant practical importance and industrial application value, and represents a pressing technical challenge that needs to be addressed by those skilled in the art. Summary of the Invention

[0007] To address the aforementioned shortcomings, this invention provides an ultra-high thermal conductivity integrated die-cast aluminum alloy and its preparation process. By precisely controlling impurities in the raw materials and optimizing the preparation process, it solves the problem that existing die-cast aluminum alloys are difficult to coordinate with thermal conductivity and mechanical properties, and cannot meet the needs of high-end heat dissipation.

[0008] To achieve the above technical objectives, the present invention adopts the following technical solution:

[0009] A manufacturing process for an ultra-high thermal conductivity integrated die-cast aluminum alloy includes the following steps:

[0010] S1. Batching and Smelting: Batchute the following materials according to the following mass percentages: Si 5.0-7.5%, Mg 0.1-0.3%, Fe 0.08-0.2%, Cu≤0.05%, Ti 0.05-0.15%, Zr 0.03-0.08%, B 0.008-0.02%, P 0.005-0.015%, Sn 0.01-0.03%, In 0.003-0.01%, with the balance being Al and unavoidable impurities, and C≤0.002%; Smelt the prepared materials under an argon protective atmosphere with low oxygen content, controlling the oxygen content of the melt to ≤0.003%;

[0011] S2. Refining and Purification: The melt obtained in step S1 is subjected to argon plasma-assisted refining. The refining is carried out under argon gas coverage, the plasma generator power is 600-800W, the melt temperature is maintained at 720-740℃, and the refining time is 10-15 minutes. After treatment, the hydrogen content of the melt is ≤0.08ml / 100g Al, and the inclusion size is ≤3μm.

[0012] S3. Melt treatment: Let the melt refined in step S2 stand for more than 10 minutes, and then thoroughly remove the surface slag.

[0013] S4. Die casting: The melt processed in step S3 is die cast. The filling pressure is 30-60MPa, and the filling speed is 0.3-0.5m / s. After filling, the mold cooling rate is ≥50℃ / s to obtain the die casting.

[0014] S5. Solution treatment: The die-casting part is kept at 440-460℃ for 1-2 hours, followed by forced air cooling.

[0015] Preferably, in the aluminum alloy, the mass percentage of Si is 6.0-7.0%, the mass percentage of Mg is 0.15-0.25%, and the mass percentage of Fe is 0.1-0.15%.

[0016] Preferably, the sum of the mass percentages of Ti and Zr in the aluminum alloy and the mass percentage of B satisfy the following condition: 5 ≤ (Ti + Zr) / B ≤ 15.

[0017] Preferably, in step S1, the B element and a portion of the Ti element are added in the form of an Al-5Ti-1B master alloy.

[0018] Preferably, in step S1, the low-oxygen melting is carried out under an argon protective atmosphere with an oxygen partial pressure ≤100Pa.

[0019] Preferably, in step S1, among the unavoidable impurities, except for C, the mass percentage of a single impurity element is ≤0.05%, and the total mass percentage of all unavoidable impurity elements is ≤0.15%.

[0020] Preferably, in the melt after step S2, the hydrogen content is controlled at 0.05-0.08 ml / 100g Al, and the inclusion size is controlled at 1-3 μm.

[0021] Preferably, in step S3, the melt is allowed to stand for 10-20 minutes.

[0022] Preferably, in step S4, the cooling rate of the mold is 60-100℃ / s.

[0023] An ultra-high thermal conductivity integrated die-cast aluminum alloy, wherein the aluminum alloy has a thermal conductivity ≥210W / (m·K), a tensile strength ≥240MPa, and an elongation ≥8%.

[0024] Compared with the prior art, the present invention has the following advantages and technical effects:

[0025] Firstly, the scientifically designed composition effectively solves the core problem of synergistically optimizing thermal conductivity and mechanical properties in existing technologies. This invention abandons the design approach of excessively adding harmful alloying elements to improve mechanical properties, as seen in existing technologies. Instead, it constructs a synergistically optimized multi-element alloy system by precisely selecting alloying elements and strictly controlling their content. On one hand, it strictly limits the content of low thermal conductivity elements to avoid damaging the thermal conductivity channels of the aluminum alloy, while precisely controlling the ratio of beneficial elements. This improves mechanical properties through solid solution strengthening without compromising thermal conductivity. On the other hand, this invention innovatively introduces various trace elements and optimizes their ratios. The synergistic effect between these trace elements achieves grain refinement and second-phase morphology control, effectively suppressing the adverse effects of coarse grains and harmful second phases on thermal conductivity and mechanical properties. Furthermore, this invention strictly controls the content of unavoidable impurity elements, especially carbon, reducing the segregation and inclusion formation of impurity elements at grain boundaries. This further ensures the purity of the internal structure of the aluminum alloy, laying the foundation for the synergistic realization of excellent thermal conductivity and mechanical properties.

[0026] Secondly, the preparation process is precise and controllable, achieving deep purification of the melt and uniform refinement of the microstructure, effectively solving the problems of incomplete melt purification and numerous microstructural defects in existing technologies. In the smelting stage, this invention employs a low-oxygen protected smelting process, which effectively isolates the melt from air contact, inhibits oxidation reactions, reduces the formation of oxide inclusions, and improves melt quality from the source. In the refining stage, an innovative argon plasma-assisted refining technology is used. Compared to traditional refining methods, this technology achieves deep purification of the melt, efficiently removing hydrogen and fine inclusions, avoiding the problems of casting porosity defects and stress concentration caused by excessive hydrogen content and large inclusions in existing technologies. Simultaneously, the optimization of melt settling further promotes the flotation and separation of residual inclusions, ensuring the purity of the melt. In the die-casting stage, the combination of low-speed filling and rapid cooling effectively avoids defects such as gas entrapment and oxidation caused by high-speed filling, while refining the as-cast microstructure, forming uniform and fine α-Al grains, reducing thermal resistance and improving mechanical property stability. The subsequent solution treatment process further optimized the internal microstructure of the alloy and improved the uniformity and reliability of its mechanical properties.

[0027] Thirdly, it exhibits excellent performance synergy, breaking through the performance bottlenecks of existing die-cast aluminum alloys and meeting the stringent requirements of high-end heat dissipation components. Through the synergistic optimization of the above-mentioned composition and process, the aluminum alloy prepared by this invention achieves a perfect balance between ultra-high thermal conductivity and excellent mechanical properties, solving the shortcomings of insufficient thermal conductivity or poor mechanical properties in existing technologies. Excellent thermal conductivity ensures rapid and efficient heat transfer, meeting the high-efficiency heat dissipation requirements of high-end equipment such as new energy vehicle motors and 5G base stations; good mechanical properties ensure that the die-cast parts can withstand complex loads and stresses during assembly and service, avoiding deformation and cracking. Simultaneously, the uniform and refined internal structure significantly reduces the performance fluctuation range of the aluminum alloy, improving the stability and consistency of product quality and solving the problems of large mechanical property fluctuations and low product qualification rates in existing technologies. Furthermore, the aluminum alloy prepared by this invention also possesses good formability, adapting to the integrated die-casting requirements of complex structure heat dissipation components, further expanding its application range.

[0028] Fourth, the process exhibits strong stability and wide applicability, possessing significant industrial application value and effectively solving the problems of unstable processes and limited application scenarios in existing technologies. The preparation process of this invention has clearly defined parameters at each stage, strong controllability, and requires no complex special equipment, making it easy to achieve industrial mass production. Compared to some complex and difficult-to-scale applications in existing technologies, it possesses greater practicality and economy. Simultaneously, the aluminum alloy prepared by this invention can precisely adapt to the usage requirements of high-end heat dissipation components such as new energy vehicle motor housings and 5G base station heat sinks. Its excellent thermal conductivity can significantly improve heat dissipation efficiency, ensuring stable equipment operation; its good mechanical and formability properties can meet the preparation and service requirements of complex structural components, contributing to the integrated and lightweight development of high-end heat dissipation components. Detailed Implementation

[0029] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0030] A manufacturing process for an ultra-high thermal conductivity integrated die-cast aluminum alloy includes the following steps:

[0031] S1. Batching and Smelting: Batchute the following materials according to the following mass percentages: Si 5.0-7.5%, Mg 0.1-0.3%, Fe 0.08-0.2%, Cu≤0.05%, Ti 0.05-0.15%, Zr 0.03-0.08%, B 0.008-0.02%, P 0.005-0.015%, Sn 0.01-0.03%, In 0.003-0.01%, with the balance being Al and unavoidable impurities, and C≤0.002%; Smelt the prepared materials under an argon protective atmosphere with low oxygen content, controlling the oxygen content of the melt to ≤0.003%;

[0032] S2. Refining and Purification: The melt obtained in step S1 is subjected to argon plasma-assisted refining. The refining is carried out under argon gas coverage, the plasma generator power is 600-800W, the melt temperature is maintained at 720-740℃, and the refining time is 10-15 minutes. After treatment, the hydrogen content of the melt is ≤0.08ml / 100g Al, and the inclusion size is ≤3μm.

[0033] S3. Melt treatment: Let the melt refined in step S2 stand, and then thoroughly remove the surface slag.

[0034] S4. Die casting: The melt processed in step S3 is die cast. The filling pressure is 30-60MPa, and the filling speed is 0.3-0.5m / s. After filling, the mold cooling rate is ≥50℃ / s to obtain the die casting.

[0035] S5. Solution treatment: The die-casting part is kept at 440-460℃ for 1-2 hours, followed by forced air cooling.

[0036] The working mechanism of this invention is as follows:

[0037] Regarding the synergistic effects of raw materials, an aluminum-based multi-element synergistic alloy system is constructed. Silicon, as the main alloying element, can improve the alloy's fluidity to adapt to die casting, and forms magnesium-silicon compounds with magnesium to produce a solid solution strengthening effect. Magnesium improves mechanical properties through solid solution strengthening, and its synergistic effect with silicon can avoid the damage to thermal conductivity caused by excessive addition of a single element. Titanium and zirconium are synergistic grain refining elements, which refine the as-cast structure by inhibiting grain growth, reducing thermal resistance and improving the stability of mechanical properties. Boron can further enhance the grain refining effect, and the controlled ratio of titanium, zirconium and boron can form a stable refining core, avoiding refining failure. Phosphorus can optimize the morphology of the second phase, inhibit the coarse precipitation of harmful second phases, and reduce the obstruction of thermal conduction channels. Tin and indium can improve the plasticity and formability of the alloy, and synergistically improve the elongation. At the same time, the content of low thermal conductivity impurities such as copper and carbon elements is strictly controlled to reduce the segregation and inclusion formation of impurities at grain boundaries, ensuring the purity of the matrix structure and laying the foundation for the synergistic improvement of thermal conductivity and mechanical properties. Some elements are added in the form of intermediate alloys, which can improve the uniformity of element dissolution, avoid local component segregation, and enhance the synergistic effect of each element.

[0038] The core mechanism of the batching and smelting process is to ensure melt quality from the source. Precise batching ensures that the proportions of each element meet the requirements for synergistic effects, avoiding performance degradation due to compositional deviations. Low-oxygen argon-protected smelting inhibits melt oxidation reactions and reduces oxide inclusions by isolating the melt from air; precise control of oxygen partial pressure further reduces oxidation tendency, preventing oxide inclusions from blocking heat conduction channels, and laying a pure melt foundation for subsequent refining and purification.

[0039] The refining and purification steps achieve deep purification through a unique mechanism of argon plasma-assisted refining. The high-energy plasma disrupts the stable state of hydrogen molecules and inclusions in the melt, promoting hydrogen escape and inclusion aggregation and flotation. Argon coverage prevents secondary oxidation and hydrogen absorption in the melt during refining. Coordinated control of refining power, temperature, and time achieves a balance between purification efficiency and melt performance, ensuring efficient removal of hydrogen and fine inclusions while avoiding component loss due to over-refining, thus ensuring the synergistic effect of each alloying element remains unaffected.

[0040] The melt treatment step allows residual inclusions to float and separate fully through settling, further improving melt purity and preventing tiny inclusions from forming internal defects during die casting, thus ensuring subsequent molding quality and performance stability. Thoroughly removing slag eliminates the adverse effects of surface impurities on die casting filling, ensuring smooth melt filling.

[0041] The die casting process achieves microstructure optimization and defect control through precise matching of process parameters. Low-speed filling avoids melt gas entrapment and oxidation, reducing defects such as porosity; controlled filling pressure ensures the melt fully fills the mold cavity, adapting to the integrated molding requirements of complex structures. Rapid cooling promotes uniform refinement of α-Al grains by increasing undercooling, reducing grain boundary thermal resistance, and suppressing coarse precipitation of the second phase, thus enhancing the synergistic effect of solid solution strengthening and grain refinement; precise control of the cooling rate avoids excessive internal stress caused by overly rapid cooling, ensuring the quality of the die-cast parts.

[0042] The solution treatment step fully dissolves the solid solution in the alloy by holding it at high temperature, thereby enhancing the solid solution strengthening effect. Forced air cooling enables rapid quenching, suppresses the precipitation of the second phase, maintains the supersaturated state of the solid solution, and further improves the uniformity and stability of mechanical properties. At the same time, it avoids grain growth and decreased thermal conductivity caused by slow cooling, ultimately achieving synergistic optimization of ultra-high thermal conductivity and excellent mechanical properties.

[0043] To make the present invention more fully disclosed, more specific embodiments are described below.

[0044] Example 1

[0045] A manufacturing process for an ultra-high thermal conductivity integrated die-cast aluminum alloy includes the following steps:

[0046] S1. Batching and Melting: Batching is performed according to the following mass percentages: Si 6.5%, Mg 0.2%, Fe 0.12%, Cu 0.03%, Ti 0.1%, Zr 0.05%, B 0.014%, P 0.01%, Sn 0.02%, In 0.006%, with the balance being Al and unavoidable impurities (C 0.001%, other individual impurities ≤0.03%, total impurities ≤0.1%). B and some Ti are added in the form of an Al-5Ti-1B master alloy. The prepared raw materials are placed in an argon protective atmosphere with an oxygen partial pressure ≤100Pa for low-oxygen melting, controlling the oxygen content of the melt to ≤0.003%.

[0047] S2. Refining and Purification: The melt obtained in step S1 is refined with argon plasma assistance. The refining is carried out under argon gas coverage, with a plasma generator power of 700W, the melt temperature is maintained at 730℃, and the refining time is 12 minutes. After treatment, the hydrogen content of the melt is 0.06ml / 100g Al, and the inclusion size is 1.8μm.

[0048] S3. Melt treatment: Let the melt refined in step S2 stand for 15 minutes, and then thoroughly remove the surface slag.

[0049] S4. Die casting: The melt processed in step S3 is die cast at a filling pressure of 45 MPa and a low filling speed of 0.4 m / s. After filling, the mold cooling rate is 80℃ / s to obtain the die casting.

[0050] S5. Solution treatment: The die-cast part is kept at 450°C for 1.5 hours, followed by forced air cooling.

[0051] Single-factor experimental design and results of key process parameters

[0052] (I) Experimental Design Principles

[0053] To screen key process parameters, the following single-factor experiments were designed. Each experiment changed only one parameter, while the other conditions were the same as the corresponding stage in Example 1.

[0054] (II) Summary of Single-Factor Experiment Results

[0055]

[0056] Conclusion and Analysis: When the (Ti+Zr) / B ratio is below 8.7, B is relatively excessive. Excess B forms coarse boride inclusions, blocking heat conduction channels and causing stress concentration, leading to a decrease in thermal conductivity and mechanical properties. When the (Ti+Zr) / B ratio is above 12.7, Ti and Zr are relatively excessive. Ti and Zr that are not combined with B form coarse intermetallic compounds, destroying the grain refinement effect, increasing thermal resistance, and reducing alloy plasticity, resulting in a decrease in performance. When the ratio is in the range of 8.7-12.7, Ti, Zr and B can fully cooperate to form small and stable grain refinement nuclei, refine grains, reduce thermal resistance and improve mechanical properties, achieving the optimal effect of element synergy.

[0057]

[0058] Conclusion and analysis: When the filling speed is too slow, the melt is prone to solidification in advance during the filling process, resulting in incomplete filling of the mold cavity, forming defects and degrading performance; when the filling speed is too fast, it will cause gas entrapment and oxidation of the melt, producing pores and oxide inclusions, blocking the heat conduction channel, and increasing internal stress, leading to reduced performance.

[0059]

[0060] Conclusion and analysis: When the cooling rate is insufficient, the undercooling is small, the α-Al grains are coarse, the thermal resistance increases, and the second phase is prone to coarse precipitation, resulting in a decrease in mechanical properties; when the cooling rate is too fast, large internal stress will be generated, and even microcracks may appear, which will destroy the integrity of the microstructure and lead to a reduction in performance.

[0061]

[0062] Conclusion and analysis: When the refining power is below 700W, the insufficient power leads to inadequate plasma disturbance and purification capabilities of the melt, failing to fully remove hydrogen and inclusions from the melt, resulting in a decrease in melt quality and consequently a reduction in thermal conductivity and mechanical properties. When the refining power is above 700W, the excessive power exacerbates the temperature fluctuations of the melt, causing some alloying elements to burn off, disrupting elemental synergy, and increasing energy consumption, which in turn leads to a decrease in performance.

[0063]

[0064] Conclusion and Analysis: When the solution temperature is below 450℃, the insufficient temperature prevents the strengthening phase in the alloy from fully dissolving into the Al matrix, resulting in inadequate solid solution strengthening. Simultaneously, insufficient matrix supersaturation leads to suboptimal strength, thermal conductivity, and plasticity of the final material. When the solution temperature is above 450℃, excessive temperature can lead to grain coarsening, increasing grain boundary thermal resistance and thus reducing thermal conductivity. Furthermore, excessively high temperatures can cause localized overheating of the alloy, weakening of grain boundaries, and even melting of the eutectic phase, severely impairing the material's mechanical properties and plasticity. Experimental results show that at a solution temperature of 450℃, the strengthening phase dissolves sufficiently without the risk of overheating, and the grain size is moderate. This results in an optimal balance between the solid solution strengthening effect, the integrity of the thermal conductivity channels, and the grain boundary bonding strength, thus achieving the best overall performance.

[0065] Example 2

[0066] A manufacturing process for an ultra-high thermal conductivity integrated die-cast aluminum alloy includes the following steps:

[0067] S1. Batching and Melting: Batching is performed according to the following mass percentages: Si 5.2%, Mg 0.18%, Fe 0.11%, Cu 0.025%, Ti 0.09%, Zr 0.045%, B 0.012%, P 0.009%, Sn 0.018%, In 0.005%, with the balance being Al and unavoidable impurities (C 0.0011%, other individual impurities ≤0.04%, total impurities ≤0.12%). B and some Ti are added in the form of an Al-5Ti-1B master alloy. The prepared raw materials are placed in an argon protective atmosphere with an oxygen partial pressure ≤100Pa for low-oxygen melting, controlling the oxygen content of the melt to ≤0.003%.

[0068] S2. Refining and Purification: The melt obtained in step S1 is refined with argon plasma assistance. The refining is carried out under argon gas coverage, with a plasma generator power of 680W, the melt temperature is maintained at 735℃, and the refining time is 11.5 minutes. After treatment, the hydrogen content of the melt is 0.058ml / 100g Al, and the inclusion size is 1.7μm.

[0069] S3. Melt treatment: Let the melt refined in step S2 stand for 14 minutes, and then thoroughly remove the surface slag.

[0070] S4. Die casting: The melt processed in step S3 is die cast at a filling pressure of 42MPa and a low filling speed of 0.42m / s. After filling, the mold cooling rate is 70℃ / s to obtain the die casting.

[0071] S5. Solution treatment: The die-cast part is kept at 452°C for 1.6 hours, followed by forced air cooling.

[0072] Example 3

[0073] A manufacturing process for an ultra-high thermal conductivity integrated die-cast aluminum alloy includes the following steps:

[0074] S1. Batching and Smelting: Batching is performed according to the following mass percentages: Si 6.0%, Mg 0.16%, Fe 0.105%, Cu 0.022%, Ti 0.085%, Zr 0.042%, B 0.011%, P 0.0085%, Sn 0.016%, In 0.0045%, with the balance being Al and unavoidable impurities (C 0.001%, other individual impurities ≤0.035%, total impurities ≤0.13%). B and some Ti are added in the form of an Al-5Ti-1B master alloy. The prepared raw materials are placed in an argon protective atmosphere with an oxygen partial pressure ≤100Pa for low-oxygen smelting, controlling the oxygen content of the melt to ≤0.003%.

[0075] S2. Refining and Purification: The melt obtained in step S1 is refined with argon plasma assistance. The refining is carried out under argon gas coverage, with a plasma generator power of 690W, the melt temperature is maintained at 728℃, and the refining time is 12.5 minutes. After treatment, the hydrogen content of the melt is 0.060ml / 100g Al, and the inclusion size is 1.8μm.

[0076] S3. Melt treatment: Let the melt refined in step S2 stand for 13 minutes, and then thoroughly remove the surface slag.

[0077] S4. Die casting: The melt processed in step S3 is die cast at a filling pressure of 43 MPa and a low filling speed of 0.38 m / s. After filling, the mold cooling rate is 75 ℃ / s to obtain the die casting.

[0078] S5. Solution treatment: The die-cast part is kept at 448°C for 1.7 hours, followed by forced air cooling.

[0079] Example 4

[0080] A manufacturing process for an ultra-high thermal conductivity integrated die-cast aluminum alloy includes the following steps:

[0081] S1. Batching and Smelting: Batching is performed according to the following mass percentages: Si 7.0%, Mg 0.22%, Fe 0.14%, Cu 0.035%, Ti 0.11%, Zr 0.055%, B 0.016%, P 0.011%, Sn 0.022%, In 0.007%, with the balance being Al and unavoidable impurities (C 0.00013%, other individual impurities ≤0.02%, total impurities ≤0.08%). B and some Ti are added in the form of an Al-5Ti-1B master alloy. The prepared raw materials are smelted under an argon protective atmosphere with an oxygen partial pressure ≤100Pa, controlling the oxygen content of the melt to ≤0.003%.

[0082] S2. Refining and Purification: The melt obtained in step S1 is refined with argon plasma assistance. The refining is carried out under argon gas coverage, with a plasma generator power of 710W, the melt temperature is maintained at 732℃, and the refining time is 11.5 minutes. After treatment, the hydrogen content of the melt is 0.056ml / 100g Al, and the inclusion size is 1.7μm.

[0083] S3. Melt treatment: Let the melt refined in step S2 stand for 16 minutes, and then thoroughly remove the surface slag.

[0084] S4. Die casting: The melt processed in step S3 is die cast at a filling pressure of 48 MPa and a low filling speed of 0.43 m / s. After filling, the mold cooling rate is 85℃ / s to obtain the die casting.

[0085] S5. Solution treatment: The die-cast part is kept at 455°C for 1.3 hours, followed by forced air cooling.

[0086] Example 5

[0087] A manufacturing process for an ultra-high thermal conductivity integrated die-cast aluminum alloy includes the following steps:

[0088] S1. Batching and Smelting: Batching is performed according to the following mass percentages: Si 7.3%, Mg 0.28%, Fe 0.18%, Cu 0.045%, Ti 0.14%, Zr 0.075%, B 0.019%, P 0.014%, Sn 0.028%, In 0.009%, with the balance being Al and unavoidable impurities (C 0.0018%, other individual impurities ≤0.05%, total impurities ≤0.15%). B and some Ti are added in the form of an Al-5Ti-1B master alloy. The prepared raw materials are smelted under an argon protective atmosphere with an oxygen partial pressure ≤100Pa, controlling the oxygen content of the melt to ≤0.003%.

[0089] S2. Refining and Purification: The melt obtained in step S1 is refined with argon plasma assistance. The refining is carried out under argon gas coverage, with a plasma generator power of 720W, the melt temperature is maintained at 738℃, and the refining time is 10.5 minutes. After treatment, the hydrogen content of the melt is 0.054ml / 100g Al, and the inclusion size is 1.9μm.

[0090] S3. Melt treatment: Let the melt refined in step S2 stand for 18 minutes, and then thoroughly remove the surface slag.

[0091] S4. Die casting: The melt processed in step S3 is die cast at a filling pressure of 55 MPa and a low filling speed of 0.48 m / s. After filling, the mold cooling rate is 95 ℃ / s to obtain the die casting.

[0092] S5. Solution treatment: The die-cast part is kept at 458°C for 1.1 hours, followed by forced air cooling.

[0093] Comparative Example 1

[0094] In the batching and smelting steps, the Cu content is 0.1%, and the remaining components and process parameters of each preparation step are the same as in Example 1.

[0095] Comparative Example 2

[0096] The refining and purification steps were carried out using traditional rotary argon refining, and the remaining components and process parameters of each preparation step were the same as in Example 1.

[0097] Comparative Example 3

[0098] In the die casting process, the mold cooling rate is 30℃ / s, and the remaining components and process parameters of each preparation step are the same as in Example 1.

[0099] Summary of experimental results:

[0100] (a) Test Results

[0101] The test results of Examples 1-5 and Comparative Examples 1-3 are shown in Table 6.

[0102]

[0103] (II) Data Comparison and Analysis

[0104] 1. Thermal conductivity analysis

[0105] The thermal conductivity range of Examples 1-5 is 214.2-223.6 W / (m·K), with Example 1 having the highest thermal conductivity at 223.6 W / (m·K). In contrast, the highest thermal conductivity of Comparative Examples 1-3 is only 203.5 W / (m·K), all failing to meet the core performance standard of 210 W / (m·K). The thermal conductivity of Example 1 is 12.7% higher than that of Comparative Example 1, 10.9% higher than that of Comparative Example 2, and 9.9% higher than that of Comparative Example 3. From a theoretical perspective, this invention achieves a breakthrough in thermal conductivity through precise component control and process optimization: on the one hand, it strictly controls the content of low thermal conductivity impurities such as Cu, reducing impurity segregation and inclusion formation at grain boundaries, avoiding blockage of thermal conduction channels, and ensuring the thermal continuity of the Al matrix; on the other hand, it employs argon plasma-assisted refining technology to achieve deep purification of the melt, effectively reducing hydrogen content and inclusion size, reducing scattering losses during heat transfer, while the low-oxygen melting process inhibits oxide inclusion formation from the source, further improving melt purity. In contrast, Comparative Example 1, due to the Cu content exceeding the limit, a large amount of low thermal conductivity Cu elements disrupted the thermal continuity of the Al matrix, resulting in significantly lower thermal conductivity; Comparative Example 2, using traditional rotary argon refining, could not achieve deep purification of the melt, leading to increased hydrogen content, larger inclusion size, and a significant increase in heat transfer resistance, limiting the improvement in thermal conductivity; Comparative Example 3, due to insufficient mold cooling speed, had coarse grains, increased thermal resistance, and its thermal conductivity failed to meet the core performance requirements of this invention.

[0106] 2. Tensile strength analysis

[0107] The tensile strength range of Examples 1-5 is 246.8-258.3 MPa, with Example 1 reaching a high tensile strength of 258.3 MPa. In contrast, the highest tensile strength of Comparative Examples 1-3 is only 245.2 MPa, generally lower than the examples. The tensile strength of Example 1 is 5.4% higher than Comparative Example 1, 11.0% higher than Comparative Example 2, and 9.6% higher than Comparative Example 3. This performance advantage stems from the multi-component synergistic strengthening mechanism of this invention: Si and Mg form the Mg2Si phase, resulting in solid solution strengthening and improving the matrix strength; Ti, Zr, and B synergistically refine the grains, improving the tensile strength of the material through the grain refinement strengthening effect; the combination of argon plasma-assisted refining and low-speed filling and rapid cooling processes effectively reduces defects such as porosity and inclusions inside the casting, avoiding stress concentration and further improving tensile strength. Comparative Example 1 had an excessive Cu content, which easily formed brittle intermetallic compounds, weakening the matrix continuity and limiting the improvement of tensile strength. Comparative Example 2 used a traditional refining process, leaving a large number of inclusions in the melt. These inclusions became stress concentration sources, easily causing crack propagation and resulting in low tensile strength. Comparative Example 3 had insufficient cooling rate, resulting in coarse grains, weakened fine grain strengthening effect, and low grain boundary strength. Under external force, it was prone to fracture, and the tensile strength could not reach the excellent level of the examples.

[0108] 3. Elongation Analysis

[0109] The elongation of Examples 1-5 ranged from 8.3% to 9.7%, with Example 1 achieving the highest elongation of 9.7%. In contrast, Comparative Examples 1-3 had an elongation of only 8.1%, none of which met the high-quality plasticity standard of over 8%. The elongation of Example 1 was 19.8% higher than Comparative Example 1, 34.7% higher than Comparative Example 2, and 29.3% higher than Comparative Example 3. The excellent elongation is attributed to the precise control of material plasticity in this invention: the appropriate addition of Sn and In elements improves the plasticity of the alloy and avoids the increase in brittleness caused by excessive single strengthening elements; the argon plasma-assisted refining technology effectively removes small inclusions in the melt, reduces crack initiation sources, and provides a guarantee for plastic deformation; the low-speed filling process avoids gas entrapment and oxidation in the melt, reduces internal defects, and at the same time, the rapid cooling process refines the grains, shortens the crack propagation path, and improves the plastic deformation capacity of the material; the solution treatment process fully dissolves the solid solution through high-temperature holding, followed by forced air cooling to maintain the supersaturated solid solution state, avoiding the coarse precipitation of the second phase and further optimizing plasticity. Comparative Example 1 had an excessive Cu content, resulting in an increase in brittle intermetallic compounds, which hindered plastic deformation and resulted in insufficient elongation. Comparative Example 2 had a high inclusion content and low grain boundary cleanliness due to the traditional refining process, which easily led to crack propagation, a significant decrease in toughness, and a significantly lower elongation. Comparative Example 3 had insufficient cooling rate, resulting in coarse grains, an extended crack propagation path, and weak grain boundary bonding, which limited plastic deformation capacity and prevented the elongation from reaching the excellent level of the examples.

[0110] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A preparation process for an ultra-high thermal conductivity integrated die-cast aluminum alloy, characterized in that, Includes the following steps: S1. Batching and Smelting: Batchute the following materials according to the following mass percentages: Si 5.0-7.5%, Mg 0.1-0.3%, Fe 0.08-0.2%, Cu≤0.05%, Ti 0.05-0.15%, Zr 0.03-0.08%, B 0.008-0.02%, P 0.005-0.015%, Sn 0.01-0.03%, In 0.003-0.01%, with the balance being Al and unavoidable impurities, and C≤0.002%; Smelt the prepared materials under an argon protective atmosphere with low oxygen content, controlling the oxygen content of the melt to ≤0.003%; S2. Refining and Purification: The melt obtained in step S1 is subjected to argon plasma-assisted refining. The refining is carried out under argon gas coverage, the plasma generator power is 600-800W, the melt temperature is maintained at 720-740℃, and the refining time is 10-15 minutes. After treatment, the hydrogen content of the melt is ≤0.08ml / 100g Al, and the inclusion size is ≤3μm. S3. Melt treatment: Let the melt refined in step S2 stand for more than 10 minutes, and then thoroughly remove the surface slag. S4. Die casting: The melt processed in step S3 is die cast. The filling pressure is 30-60MPa, and the filling speed is 0.3-0.5m / s. After filling, the mold cooling rate is ≥50℃ / s to obtain the die casting. S5. Solution treatment: The die-casting part is kept at 440-460℃ for 1-2 hours, followed by forced air cooling.

2. The preparation process of the ultra-high thermal conductivity integrated die-cast aluminum alloy according to claim 1, characterized in that, In the aluminum alloy, the mass percentage of Si is 6.0-7.0%, the mass percentage of Mg is 0.15-0.25%, and the mass percentage of Fe is 0.1-0.15%.

3. The preparation process of the ultra-high thermal conductivity integrated die-cast aluminum alloy according to claim 1, characterized in that, The sum of the mass percentages of Ti and Zr in the aluminum alloy and the mass percentage of B satisfy the following condition: 5 ≤ (Ti + Zr) / B ≤ 15.

4. The preparation process of the ultra-high thermal conductivity integrated die-cast aluminum alloy according to claim 1, characterized in that, In step S1, the B element and part of the Ti element are added in the form of an Al-5Ti-1B master alloy.

5. The preparation process of the ultra-high thermal conductivity integrated die-cast aluminum alloy according to claim 1, characterized in that, In step S1, the low-oxygen melting is carried out under an argon protective atmosphere with an oxygen partial pressure ≤100Pa.

6. The preparation process of the ultra-high thermal conductivity integrated die-cast aluminum alloy according to claim 1, characterized in that, In step S1, among the unavoidable impurities, except for C, the mass percentage of a single impurity element is ≤0.05%, and the total mass percentage of all unavoidable impurity elements is ≤0.15%.

7. The preparation process of the ultra-high thermal conductivity integrated die-cast aluminum alloy according to claim 1, characterized in that, In the melt after step S2, the hydrogen content is controlled at 0.05-0.08 ml / 100g Al, and the inclusion size is controlled at 1-3 μm.

8. The preparation process of the ultra-high thermal conductivity integrated die-cast aluminum alloy according to claim 1, characterized in that, In step S3, the melt is allowed to stand for 10-20 minutes.

9. The preparation process of the ultra-high thermal conductivity integrated die-cast aluminum alloy according to claim 1, characterized in that, In step S4, the cooling rate of the mold is 60-100℃ / s.

10. An ultra-high thermal conductivity integrated die-cast aluminum alloy obtained by the preparation process according to any one of claims 1-9, characterized in that, The aluminum alloy has a thermal conductivity ≥210W / (m·K), a tensile strength ≥240MPa, and an elongation ≥8%.

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