고온열전재료 $FeSi_2$의 변태거동

Transformation Behaviour of High Temperature Thermoelectric $FeSi_2$

  • 은영효 (연세대학교 공과대학 금속공학과) ;
  • 민병규 (연세대학교 공과대학 금속공학과) ;
  • 이동희 (연세대학교 공과대학 금속공학과)
  • Eun, Young-Hyo (Dept. of Metallurgical Engineering, Yonsei University) ;
  • Min, Byoung-Gue (Dept. of Metallurgical Engineering, Yonsei University) ;
  • Lee, Dong-Hi (Dept. of Metallurgical Engineering, Yonsei University)
  • 발행 : 1995.09.01

초록

In the Fe-Si system, a mixture of a($Fe_{2}Si_5$) - and ${\epsilon}$(FeSi)-composition powders was sintered and heat-treated subsequently at various temperatures and time to get thermoelectric ${\beta}$-phase($FeSi_2$) compacts. The different transformational sequences depending on the heat treating temperature were found through the investigation into phase transformation and microstructural development. That is, a rapid eutectoid decomposition of ${\alpha}{\to}{\beta}+Si$ occurred together with a accompanying slow reaction between the dispersed Si formed by above decomposition and the preexisted ${\epsilon}$ phase at temperatures below $830^{\circ}C$. The unreacted Si and the micropores formed due to the density change upon the transformation coarsened as heat treating time elapsed. At temperatures above $880^{\circ}C$, however, transformation was proceeded by a peritectoid reaction of ${\alpha}+{\epsilon}{\to}{\beta}$. It took at least 200min. to achieve 90% volume fracion of transformed ${\beta}$ phase, and the growth of micro-pores was also observed in this transformational sequence with prolonged heat treating time.

키워드