Interface energies of hetero- and homo-phase boundaries and their impact on δ-γ Massive-like phase transformations in carbon steel

Masato Yoshiya, Kenta Nakajima, Manabu Watanabe, Nobufumi Ueshima, Tomoya Nagira, Hideyuki Yasuda

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Systematic atomistic simulations of homo- and hetero-phase boundaries have been carried out to quantify interphase boundary energies in iron including δ-phase and γ-phase grain boundaries and δ/γ, δ/liquid and γ/liquid interfaces. Due to structural mismatch between body centered cubic (BCC) and face centered cubic (FCC) structures of the δ and γ phases, the minimum interface energy of the δ/γ interface is as high as 0.41 J/m2, much higher than the minimum interface energies of the δ/δ and γ/γ homo-phase interfaces, which are zero, suggesting that the high interface energy is one of the key factors that lead to the massive-like phase transformation from the δ phase to the γ phase observed by in situ radiography. Although the minimum δ/γ interface energy is not significantly higher than the δ/liquid interface energy that determines the δ nucleation upon solidification, it is yet high enough for the small entropy change upon the phase transformation to inhibit γ nucleation at a given critical radius until more than one orders of magnitude higher undercooling is achieved according to the classical theory of homogeneous nucleation.

Original languageEnglish
Pages (from-to)1461-1466
Number of pages6
JournalMaterials Transactions
Volume56
Issue number9
DOIs
Publication statusPublished - 2015 Jan 1

Keywords

  • Atomistic simulation
  • Carbon steel
  • Grain boundaries
  • Interface energy
  • Nucleation
  • Phase transformation

ASJC Scopus subject areas

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

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