Microstructure and performance of Al-Si alloy with high Si content by high temperature diffusion treatment

Abstract The Al-Si alloy with high Si content was prepared by pressure infiltration. Microstructure observation shows that three-dimensional structure (3D-structure) is obtained from irregular sharp Si particles via high temperature diffusion treatment (HTDT). Flat Si-Al interfaces transform to smooth curves, and Si phases precipitate in Al and Si-Al interface. The bonding of Si-Al interface is improved by HTDT, which improves the mechanical performance of Al-Si alloy. The bending strength of 3D-Al-Si alloy increases by 6% compared with that of Al-Si alloy, but the elastic modulus changes a little. The coefficient of thermal expansion (CTE) of the 3D-Al-Si alloy is 7.7×10 −6 /°C from 20 °C to 100 °C, which decreases by 7% compared with that of Al-Si alloy. However, HTDT has little effect on the thermal conductivity of Al-Si alloy.