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.