A Quantitative Study on the Interaction Between Silicon Content and Heat Treatment on Thermal Conductivity of Al-Si Binary Alloys

In this study, the room temperature thermal conductivities and microstructures of Al-Si binary alloys in as-cast, low-temperature annealing state and solid solution state are investigated. The experimental results show that annealing treatment increases the thermal conductivities of these alloys because of the decreasing Si concentration in α-Al matrix, which is determined by EPMA. The effect of solution treatment on the thermal conductivity of Al-xSi (0 ≤ x ≤ 12) alloys can be divided into two stages. When the Si content is less than 3 wt%, the thermal conductivities of solution treated specimens are lower than that of as-cast, which is mainly attributed to the increase in Si concentration. However, solution treatment improves the thermal conductivities of Al-xSi (x > 3) alloys owing to the spheroidization of Si phase. Quantitative study is conducted on the effect of Si element on thermal conductivity of as-cast Al-xSi alloys. The thermal conductivities of Al-xSi alloys are fitted using modified Series and Maxwell models based on the Si concentration in α-Al matrix, distribution and volume fractions of Si phases. The modified structural models provide a better fit to the measured thermal conductivity data.