Estimation of the system free energy of martensite phase in an Fe-Cr-C ternary alloy

Tomonori Kunieda, Masaaki Nakai, Yoshinori Murata, Toshiyuki Koyama, Masahiko Morinaga

Research output: Contribution to journalArticlepeer-review

49 Citations (Scopus)


The system free energy was estimated for the martensite phase of an Fe-Cr-C ternary alloy. The system free energy of the martensite phase is defined as, Gsys=G0+Estr+Esurf, where G 0 is the chemical free energy, Esurf is the interfacial energy for the boundaries in the martensite microstructure, and Estr is the elastic strain energy due to the dislocations in the martensite phase. From the experimental results on SEM/EBSD, the interfacial energy was estimated to be 0.05J/mol for the prior austenite boundary, 0.11 J/mol for the martensite packet boundary and 0.32 J/mol for both the martensite block and the lath boundaries in the asquenched specimen. The total decrement in the interfacial energy accompanying annealing at 873 K for 100 h after quenching was estimated to be about 0.1 J/mol. Also, the elastic strain energy of the asquenched specimen was estimated to be 7.1 J/mol. The total microstructural energy of the martensite phase was about 10 J/mol, which operates as a driving force for the microstructure evolution, e.g., recovery of dislocations and the coarsening of the sub-structures such as martensite-packet, -block and -lath.

Original languageEnglish
Pages (from-to)1909-1914
Number of pages6
JournalIsij International
Issue number12
Publication statusPublished - 2005
Externally publishedYes


  • Dislocation density
  • Heat-resistant steel
  • Interfacial energy
  • Martensite phase
  • Microstructure evolution
  • System free energy

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering
  • Metals and Alloys
  • Materials Chemistry


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