高导热AlSi12Fe铸造铝合金的组织和性能

Microstructure and thermal properties of AlSi12Fe casting aluminum alloy with high thermal conductivity

试验研究了变质元素Sr和Ca对新开发的高导热AlSi12Fe铸造铝合金导热性能的影响,以及工业批量化生产AlSi12Fe铸造铝合金铸锭的组织和性能,并进行了该合金压铸件应用于通信机箱的可行性研究。结果表明:Sr和Ca均能通过对共晶硅的变质作用来提高AlSi12Fe铸造铝合金的热导率,且Sr的改善作用比Ca的更明显,当添加w(Sr)=0.03%0.05%时效果最优;AlSi12Fe铸造铝合金锭横截面各个位置的电导率有所差异,这主要与冷却速率有关,最先冷却凝固位置的α-Al、共晶硅和Fe相更为细小,因而电导率和热导率更好;采用AlSi12Fe铸造铝合金可顺利压铸1.8 mm厚、60 mm高的复杂薄壁通信机箱散热翅片,机箱压铸态的热导率为160 W/(m·K),经时效热处理后热导率可达172 W/(m·K)。

The experiment was carried out to research the effects of modified agents Sr and Ca on the thermal conductivity of newly developed AlSi12Fe cast aluminum alloy with high thermal conductivity,and also the microstructure and properties of the cast ingot of AlSi12Fe aluminum alloy produced in mass production. Then the feasibility was investigated on whether this die cast could be used for communication enclosure. The results show that both Sr and Ca can improve the thermal conductivity of the alloy via modification of eutectic silicon,and Sr plays more significant role than Ca. The best improvement can be obtained when Sr is 300-500 ppm. The electric conductivities are different on different points of the ingot section,mainly related to various cooling rates. The α-Al dendrites,eutectic silicon and Fe-rich phase are finer at the position with higher cooling rate than those with lower. AlSi12Fe cast aluminum alloy can be die cast into complex thin fins of communication enclosure,which is 1. 8 mm thick and 60 mm high. The thermal conductivity of the enclosure is 160 W/（m·K） as die-casting state,while after heat treatment the thermal conductivity can reach 172 W/（m·K）.