持続型固−液共存状態を利用した放熱用金属基複合材料の緻密化および高性能化プロセスの開発

概要

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Diamond-particle-dispersed-aluminum (Al) matrix composites were fabricated in a unique fabrication method where continuous solid-liquid coexistent 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 798 K and 876 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-Euckens equation. The coefficient of thermal expansion of the composites falls in the upper line of Kerners model, indicating strong bonding between the diamond particle and the Al matrix in the composite. Based on the experimental results obtained in the present study, densification process in continuous solid-liquid co-existent state is considered to be a quite effective methodology for enhancing performance of heat dissipative metal matrix composites.