Yuji Ohishi1, Shingo Okajima1, Yoshinobu Miyazaki1, Hiroaki Muta1, Ken Kurosaki1 and Shinsuke Yamanaka1,2
1Graduate School of Engineering, Osaka University, Suita 565-0871
In the present study, we synthesized composite material composed of Si and β-FeSi2 by self-assembly process. In this process, mesoscale α-FeSi2 and Si crystals were formed by rapidly solidifying Fe-Si alloys with eutectic composition (Fe:Si=26:74) using melt spinning. Nanoscale β-FeSi2 and Si crystals were formed by subsequent heat treatment by eutectoid decomposition from α-FeSi2 to β-FeSi2 and Si. Scanning electron microscope observation showed that two kinds of Si precipitates were formed in the β-FeSi2 matrix: Si particle with a diameter of 100–200 nm and Si nanoscale lamellar plates with a thickness of about 50 nm. The thermal conductivity of the composite was significantly reduced compared to the effective thermal conductivity of Si and β-FeSi2 composite calculated based on effective medium approximation. This result indicates that the thermal conductivity was reduced by enhanced phonon scattering by the formed nanostructure.
thermal conductivity, eutectic reaction, eutectoid decomposition
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