Korean Journal of Materials Research (한국재료학회지)

Materials Research Society of Korea (한국재료학회)
권호 표지

Phase Transformation During Hot Consolidation and Heat Treatments in Mechanically Alloyed Iron Silicide

기계적 합금화 Iron Silicide의 열간성형 및 열처리에 의한 상변화

  • Eo, Sun-Cheol (Dept. of Materials Science and Engineering/Nano Technology Lab., Chungju National University) ;
  • Kim, Il-Ho (Dept. of Materials Science and Engineering/Nano Technology Lab., Chungju National University) ;
  • Hwang, Seung-Jun (Daejin University) ;
  • Jo, Gyeong-Won (Dept. of Materials Engineering, Chungbuk National University) ;
  • Choe, Jae-Hwa (Dept. of Materials Engineering, Chungbuk National University)
  • 어순철 (충주대학교 재료공학과/나노기술연구소) ;
  • 김일호 (충주대학교 재료공학과/나노기술연구소) ;
  • 황승준 (대진대학교 신소재공학과) ;
  • 조경원 (충북대학교 재료공학과) ;
  • 최재화 (충북대학교 재료공학과)
  • Published : 2001.12.01
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Abstract

An n-type iron$silicide(Fe_{0.98}Co_{0.02}Si_2)$has been produced by mechanical alloying process and consolidated by vacuum hot pressing. Although as-milled powders after 120 hours of milling did not show an alloying progress,${\beta}-FeSi_2$phase transformation was induced by isothermal annealing at$830{\circ}C$for 1 hour, and the fully transformed${\beta}-FeSi_2$phase was obtained after 4 hours of annealing. Near fully dense specimen was obtained after vacuum hot pressing at$ 1100{\circ}C$with a stress of 60MPa. However, as-consolidated iron silicides were consisted of untransformed mixture of ${\Alpha}-Fe_2Si_5$and ${\varepsilon-FeSi$phases. Thus, isothermal annealing has been carried out to induce the transformation to a thermoelectric semiconducting${\beta}-FeSi_2$phase. The condition for${\beta}-FeSi_2$transformation was investigated by utilizing DTA, SEM, and XRD analysis. The phase transformation was shown to be taken place by a vacuum isothermal annealing at$830{\circ}C$and the transformation behaviour was investigated as a function of annealing time. The mechanical properties of${\beta}-FeSi_2$materials before and after isothermal annealing were characterized in this study.

Keywords

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