Thermal Properties of Al/AlN Composites Fabricated in Continuous Solid-Liquid Co-Existent State by SPS

Aluminum nitride (AlN)-particle-dispersed-aluminum (Al) matrix composites were fabricated by Spark Plasma Sintering (SPS) process from the mixture of AlN powders, Al powders and Al-5mass%Si powders. The microstructures, thermal conductivities and thermal expansions of the composites fabricated were examined. These composites were all well consolidated by heating at a temperature range between 798 K and 876 K for 1.56 ks during SPS process. No reaction at the interface between the AlN particle and the Al matrix was observed by scanning electron microscopy for the composites fabricated under the sintering conditions employed in the present study. The relative packing density of the Al/AlN composite fabricated was almost 100 % in a volume fraction range of AlN between 40 % and 60 %. Thermal conductivity of the Al/AlN composite was higher than 180 W/mK at the AlN fraction range between 40 and 65 vol.%, approximately 90 % the theoretical thermal conductivity estimated using Maxwell-Eucken's equation. The coefficient of thermal expansion of the composites falls in the upper line of Kerner's model, indicating strong bonding between the AlN particle and the Al matrix in the composite.