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Phase Transformation and Thermoelectric Properties of Fe0.92Mn0.08Si2 Prepared by Mechanical Alloying

기계적 합금화로 제조된 Fe0.92Mn0.08Si2의 상변화 및 열전 특성

  • Kim, Young-Seob (Dept. of Materials Science & Engineering/Nano Technology Lab., Chungju National University) ;
  • Cho, Kyung-Won (Dept. of Materials Science & Engineering/Nano Technology Lab., Chungju National University) ;
  • Kim, Il-Ho (Dept. of Materials Science & Engineering/Nano Technology Lab., Chungju National University) ;
  • Ur, Soon-Chul (Dept. of Materials Science & Engineering/Nano Technology Lab., Chungju National University) ;
  • Lee, Young-Geun (Dept. of Materials Science & Engineering/Nano Technology Lab., Chungju National University)
  • 김영섭 (충주대학교 신소재공학과/나노기술연구소) ;
  • 조경원 (충주대학교 신소재공학과/나노기술연구소) ;
  • 김일호 (충주대학교 신소재공학과/나노기술연구소) ;
  • 어순철 (충주대학교 신소재공학과/나노기술연구소) ;
  • 이영근 (충주대학교 신소재공학과/나노기술연구소)
  • Published : 2003.05.01

Abstract

In an attempt to enhance phase transformation and homogenization of Mn-doped $FeSi_2$, mechanical alloying of elemental powders was applied. Cold pressing and sintering in vacuum were carried out to produce a dense microstructure, and then isothermal annealing was employed to induce a phase transformation to the $\beta$-$FeSi_2$semiconductor. Phase transitions in this alloy system during the process were investigated by using XRD, EDS and SEM. As-milled powders after 100 h of milling were shown to be metastable state. As-sintered iron silicides consisted of untransformed mixture of $\alpha$-$Fe_2$$Si_{5}$and $\varepsilon$-FeSi phases. $\beta$-$FeSi_2$phase transformation was induced by subsequent isothermal annealing at $830^{\circ}C$, and near single phase of $\beta$-$FeSi_2$was obtained after 24 h of annealing. Thermoelectric properties in terms of Seebeck coefficient, and electrical conductivity were evaluated and correlated with phase transformation. Seebeck coefficient electrical resistivity and hardness increased with increasing annealing time due to $\beta$ phase transformation.

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