Effect of additives on the phase equilibria related to the E2 1-Fe3AlC intermetalic compound with carbon atom at the interstitial site

Hiroaki Ishii, Seiji Miura, Tetsuo Mohri

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The structure of E21 is a derivative of L12 structure with an interstitial carbon in the body center or the octahedral interstitial site. In the Fe-Al-C ternary system E21-Fe 3AlC intermetallic is known to precipitate in γ-austenite alloys. For the high temperature application, the stability of microstructure is a key issue and the control of the lattice misfit is essential. By adding some elements to Fe-Al-C alloys, the lattice constant can be controlled, and enhancement of the stability of γ-austenite + E21-Fe 3AlC two phase structure is expected. In this study, phase stability and lattice parameter of E21 phase in the (Fe-Mn)-(Al-M)-C system (M=Si, Ge) are investigated. In both systems, no significant changes in microstructures were observed within the composition range of concern. The lattice constant of E21-Fe3AlC phase, however, does not show decrease with the addition of Si or Ge. This result is different from what was expected. By WDS analysis, it was revealed that Si tends to distribute mainly in γ phase, and Ge concentrates in E21-Fe 3AlC phase. It was found that the lattice constants of E2 1 phases are very close to those of L12 structure estimated from the atomic radii of constituent elements which are evaluated from those in binary alloys and compounds. The distribution behavior of Si and Ge can be related to tolerance factor which strongly affects the stability of phases.

Original languageEnglish
Pages (from-to)351-356
Number of pages6
JournalMaterials Research Society Symposium - Proceedings
Publication statusPublished - 2003 Nov 10
EventDefect Properties and Related Phenomena in Intermetallic Alloys - Boston, MA, United States
Duration: 2002 Dec 32002 Dec 5

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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