Synchronously Improving the Thermal Conductivity and Mechanical Properties of Al–Si–Fe–Mg–Cu–Zn Alloy Die Castings Through Ultrasonic-Assisted Rheoforming
Synchronously Improving the Thermal Conductivity and Mechanical Properties of Al–Si–Fe–Mg–Cu–Zn Alloy Die Castings Through Ultrasonic-Assisted Rheoforming
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DOI：
10.1007/s40195-021-01231-3
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发表时间：
2021-05
期刊：
影响因子：
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通讯作者：
M. Qi;Y. Kang;Jingyuan Li;Yuzhao Xu;Jicheng Wang;Gunan Li;Aisen Liu
中科院分区：
文献类型：
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作者：
M. Qi;Y. Kang;Jingyuan Li;Yuzhao Xu;Jicheng Wang;Gunan Li;Aisen Liu
采用超声振动辅助风冷搅拌棒工艺（ACSR + UV）高效制备了质量大于40 kg的大体积半固态浆料。研制了一种低成本、高导热、高塑性、中等强度的Al-Si-Fe-Mg-Cu-Zn压铸合金。该合金通过ACSR + UV流变压铸（ACSR + UV R-DC）工艺用于制造5G基站的大型薄壁零件。研究了ACSR + UV R-DC合金的显微组织、孔隙率、力学性能、断裂行为和导热性能，并与传统压铸（T-DC）和ACSR R-DC合金进行了比较。分析了ACSR + UV R-DC合金组织细化、力学性能和导热性能提高的机理。结果表明，ACSR + UV工艺由于形核面积的增加和空化气泡的产生，提高了熔体的形核速率。在声流和机械搅拌的联合作用下，熔体内部也产生了径向和轴向强制对流，从而使熔体组成场和温度场均匀化。因此，ACSR + UV R-DC工艺不仅细化了初生α-Al（α1-Al）、共晶硅和次生α-Al（α2-Al），而且显著改善了β-Al 5 FeSi相的形貌和分布。ACSR + UV R-DC合金的力学性能高于T-DC合金和ACSR R-DC合金。与T-DC合金相比，ACSR + UV R-DC合金的抗拉强度、伸长率和屈服强度分别提高了34%、122%和19%。这是因为ACSR + UV R-DC技术使合金具有高密度、细小的球形α1-Al晶粒和细小均匀的β相的特征，从而改善了合金的断裂行为。ACSR + UV R-DC合金的热导率为184 W/（mK），比T-DC和ACSR R-DC合金分别提高了10.2%和3.4%。这是因为ACSR + UV R-DC合金中细化的共晶硅和β相有利于电子更容易流过共晶区，并且孔隙率的降低增加了热传导的有效面积。
An ultrasonic vibration-assisted air-cooled stirring rod process (ACSR + UV) was used to efficiently prepare a large-volume semisolid slurry with a mass of more than 40 kg. A low-cost Al–Si–Fe–Mg–Cu–Zn die-casted alloy with high thermal conductivity, high plasticity and medium strength was developed. The alloy was used to manufacture large, thin-walled parts for 5G base stations by using the ACSR + UV rheological die-casting (ACSR + UV R-DC) process. Investigations were performed on the microstructure, porosity, mechanical properties, fracture behaviour and thermal conductivity of the ACSR + UV R-DC alloy, which was then compared to traditionally die-casted (T-DC) and ACSR R-DC alloys. The mechanisms for the microstructural refinement and enhancement of the mechanical and thermal conductivity performances of the ACSR + UV R-DC alloy were also analysed. The results showed that the ACSR + UV process increased the nucleation rate of the melt due to the increase in the nucleation area and the generation of cavitation bubbles. A radial- and an axial-forced convection was also generated inside the melt under the combined effects of acoustic flow and mechanical stirring, thereby homogenising the melt composition field and the temperature field. Therefore, the ACSR + UV R-DC process not only refined the primaryα-Al (α1-Al), the eutectic silicon and the secondaryα-Al (α2-Al), but also greatly improved the morphology and the distribution of theβ-Al5FeSi phase. The mechanical properties of the ACSR + UV R-DC alloy were higher than those of the T-DC and the ACSR R-DC alloys. Compared to the T-DC alloy, the ultimate tensile strength, elongation and yield strength of the ACSR + UV R-DC alloy were increased by 34%, 122% and 19%, respectively. This was because the ACSR + UV R-DC technique gave the alloy the characteristics of high density, fine sphericalα1-Al grain and a fine and uniformβ-phase, which improved the fracture behaviour of the alloy. The thermal conductivity of the ACSR + UV R-DC alloy was 184 W/(m K), which was 10.2% and 3.4% higher than that of T-DC and ACSR R-DC alloys, respectively. This was because the refined eutectic silicon andβphases in the ACSR + UV R-DC alloy facilitated an easier electron flow through the eutectic region, and the decrease in porosity increased the effective area of heat conduction.