Diamond-particle-dispersed-aluminum (Al) matrix composites were fabricated in continuous solid-liquid co-existent state by Spark Plasma Sintering (SPS) process from the mixture of diamond powders, pure Al powders and Al-5mass%Si alloy powders. The microstructures and thermal conductivities 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 diamond 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 diamond-Al composite fabricated was 99 % or higher in a volume fraction range of diamond between 45 % and 50 %. Thermal conductivity of the diamond-Al composite containing 50 vol.% diamond reached 552 W/mK, approximately 95 % the theoretical thermal conductivity estimated using Maxwell-Eucken's equation. The coefficient of thermal expansion of the composites fell in the upper line of Kerner model, indicating strong bonding between the diamond particle and the Al matrix in the composite.
