Microstructure and Heat Transfer Performance of Al-9Si-xCu Alloys for Permanent Mold Casting

Author of the article:ZHU Huiying, WENG Wenping, WANG Dongtao, HIROMI Nagaumi, WANG Yajing, HUANG Pengyu

Author's Workplace：School of Iron and Steel, Soochow University, Suzhou 215137, China

Key Words：Al-Si alloy; Cu element; microstructure; thermal conductivity

Abstract：The effect of Cu on the microstructure and heat transfer properties of Al-9Si alloys achieved by water-cooled copper mold casting has been investigated. The results show that the decreasing trend of thermal conductivity with various Cu contents is different. When the Cu content increases from 0 to 0.83%, the presence of Cu in the matrix as a replacement solid solution causes lattice distortion and increases the chance of free electron scattering, deteriorating the thermal conductivity from 164.54 W/(m·K) to 149.02 W/(m·K). As the Cu content increases from 0.83% to 2.00%, the added Cu reaches the saturated state and exists as a Cu-rich phase in the matrix, which has relatively little effect on the thermal conductivity. When the Cu content exceeds 2.65%, Cu-rich phases grow further and decrease in number. The changes in morphology, number and distribution of Cu-rich phases are conducive to free electron transport, thus slowing down the decrease in thermal conductivity with increasing Cu content