Measurement of Volume Fraction of ${\varepsilon}$ Martensite using Specific Volume Difference in Fe-Mn Based Alloys

Fe-Mn 계 합금에서 비부피 차를 이용한 ${\varepsilon}$ 마르텐사이트의 부피분율 측정

  • Jee, K.K. (Div. of Materials, Korea Institute of Science of Technology) ;
  • Han, J.H. (Div. of Materials, Korea Institute of Science of Technology) ;
  • Jang, W.Y. (Dept. of Metallurgical Engineering, Chosun Univ.)
  • 지광구 (한국과학기술연구원 재료연구부) ;
  • 한준현 (한국과학기술연구원 재료연구부) ;
  • 장우양 (조선대학교 신금속소재공학과)
  • Received : 2003.05.19
  • Published : 2003.07.31

Abstract

In this work, a new way of measuring the volume fraction of e martensite in Fe-based alloys has been proposed. Since the specific volume of ${\varepsilon}$ martensite, depending on alloy composition, is smaller than that of austenite i.e ${\gamma}$ phase, volume expansion takes place during ${\varepsilon}{\rightarrow}{\gamma}$ reverse transformation. As the amount of the volume expansion is proportional to the product of specific volume difference times the volume fraction of ${\varepsilon}$ martensite, the volume fraction of ${\varepsilon}$ martensite can be calculated by measuring the volume expansion and the specific volume difference. Such a relationship was confirmed in Fe-21Mn and Fe-32Mn-6Si alloys which undergo ${\gamma}{\rightarrow}{\varepsilon}$ martensitic transformation on cooling and by cold rolling, respectively. It was also found that the former has isotropic ${\varepsilon}$ martensite while the latter has anisotropic ${\varepsilon}$ martensite.