Microstructure and thermal/mechanical properties of hot-extruded aluminum/graphite composites with Al-Si alloy addition

摘要

Al/graphite composites with small amounts of Al-Si alloy were consolidated by spark plasma sintering and hot-extrusion processes. The effect of Al-Si alloy addition on densification behavior, microstructure, thermal conductivity (TC), coefficient of thermal expansion (CTE), and compressive strength has been systematically investigated. The results showed that the addition of Al-Si alloy resulted in improvements in relative density of the composites, interfacial bonding between Al and graphite, and orientation degree of graphite. The composites with Al-Si alloy showed improved TC and reduced CTE values in comparison with those without Al-Si alloy. For example, the 450 degrees C-extruded Al/60 vol% graphite/9 vol% Al-Si composite showed a maximum TC of 297Wm(-1) K-1 and a minimum CTE of 7.95ppmK(-1). Moreover, the hot-extruded Al/graphite composites containing Al-Si alloy exhibited higher compressive strength compared to conventional squeeze-cast composites and hot-extruded composites without Al-Si alloy.