Microstructure Characterization and Properties of Cast Al-Si-Fe-Zn Alloys with High Thermal Conductivity

Recently, demand of die-cast aluminum alloys for manufacturing heat dissipator with high thermal conductivity increases. However, most of the commercial die-cast aluminum alloys yield very low thermal conductivity, far lower than that of pure aluminum for high content of alloying elements. In this paper, Three kinds of low-silicon cast aluminum alloys, Al-(1-2)Si-1Fe-1Zn and Al-1Si-0.2Mg-1Fe-1Zn, are investigated for their potential to obtain the ideal combination of high thermal conductivity and good castability. The work shows that Al-1Si-1Fe-1Zn alloy can achieve a thermal conductivity of 184 W/(m K) under as-cast condition, while Al-1Si-0.2Mg-1Fe-1Zn alloy exhibits slightly lower thermal conductivity but better casting fluidity and mechanical properties, and Al-2Si-1Fe-1Zn alloy shows both poor thermal conductivity and fludity than the others. A proper heat treatment can improve thermal conductivity and mechanical propeties at the same time for Al-1Si-0.2Mg-1Fe-1Zn alloy.