Processing of diamond particle dispersed aluminum matrix composites in continuous solid-liquid co-existent state by SPS and their thermal properties

Diamond-particle-dispersed-aluminum (Al) matrix composites were fabricated in a unique fabrication method where continuous solid-liquid co-existent state of the powder mixture of diamond, pure Al and Al-5mass%Si alloy was designed during spark plasma sintering (SPS) process. Microstructures and thermal properties of the composites fabricated in such a way were investigated. The composites can be well consolidated in the temperature range between 773 K and 878 K and scanning electron microscopy detects no reaction at the interface between the diamond particle and the Al matrix. The relative packing density of the diamond-Al composite fabricated was 99% or higher in a volume fraction range of diamond between 35 and 50%. The thermal conductivity of the diamond-Al composite containing 50 vol.% diamond reached 552 W/mK, higher than 95% the theoretical thermal conductivity calculated by 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 diamond particle and the Al matrix in the composite. (C) 2011 Elsevier Ltd. All rights reserved.