Concurrent γ-Phase Nucleation as a Possible Mechanism of δ-γ Massive-like Phase Transformation in Carbon Steel: Numerical Analysis Based on Effective Interface Energy

• Yoshiya Masato

  Department of Adaptive Machine Systems, Osaka University Nanostructures Research Laboratory, Japan Fine Ceramics Center

• Watanabe Manabu

  Department of Adaptive Machine Systems, Osaka University

• Nakajima Kenta

  Department of Adaptive Machine Systems, Osaka University

• Ueshima Nobufumi

  Department of Adaptive Machine Systems, Osaka University

• Hashimoto Koki

  Department of Adaptive Machine Systems, Osaka University

• Nagira Tomoya

  Department of Adaptive Machine Systems, Osaka University

• Yasuda Hideyuki

  Department of Adaptive Machine Systems, Osaka University Department of Materials Science and Engineering, Kyoto University

書誌事項

タイトル別名

• Concurrent γ-Phase Nucleation as a Possible Mechanism of δ-γ Massive-like Phase Transformation in Carbon Steel: Numerical Analysis Based on Effective Interface Energy

抄録

Effective interface energies of various homo- and hetero-interfaces of iron were calculated with an aid of phase-field modeling, taking into account geometric constraints by competition among grains or interfaces. Calculated effective interface energies for δ/γ, δ/δ, and γ/γ interfaces are 0.56, 0.44 and 0.37 J/m², respectively. Using two simple geometric models for nucleation on or off an interface in the matrix, the optimal shape of a nucleus at a given radius and undercooling, a critical radius and an energy barrier for nucleation for each possible circumstance were numerically calculated. It is found that, although the energy barrier for γ-phase nucleation in homogeneous δ-phase matrix is more than three orders of magnitude greater than that for homogeneous solidification of δ-phase, the γ nucleation on a δ/δ grain boundary in the solidifying matrix suppresses the energy barrier, increasing a nucleation rate. Furthermore, it is found that the γ-phase nucleation on an existing γ nucleus halves undercooling needed with smaller critical radius. This suggests that, once γ nucleation is initiated, then following γ nucleation is promoted by doubled driving force, enabling multiple γ nucleation as in chain reaction. These findings are sufficient to explain experimentally observed phenomena during the δ-γ massive-like phase transformation even if other factors such as solute re-distribution or transformation is neglected.

収録刊行物

• MATERIALS TRANSACTIONS

  MATERIALS TRANSACTIONS 56 (9), 1467-1474, 2015

  公益社団法人 日本金属学会

キーワード

• steel
• concurrent nucleation
• phase transition
• phase field model
• interface energy
• massive transformation

詳細情報

• CRID: 1390001204253147904
• NII論文ID: 130005094796
• NII書誌ID: AA1151294X
• DOI: 10.2320/matertrans.ma201569
• ISSN: 13475320
• ISSN: 13459678
• NDL書誌ID: 026709503
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I026709503
• Web Site: https://www.jstage.jst.go.jp/article/matertrans/56/9/56_MA201569/_pdf
• 本文言語コード: en
• データソース種別:
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