Kinetics of the δ/γ interface in the massive-like transformation in Fe-0.3C-0.6Mn-0.3Si alloys

Nishimura, Tomohiro; Morishita, Kohei; Nagira, Tomoya; Yoshiya, Masato; Yasuda, Hideyuki

doi:10.1088/1757-899x/84/1/012062

Cited by 22 publications

(23 citation statements)

References 11 publications

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“…The X-ray imaging techniques were also applied to observe solidification of Fe-based alloys. [9][10][11][12][13] According to the time-resolved and in-situ observations of Fe-C alloys, 12,13) nucleation of γ phase hardly occurred at or below the peritectic temperature and consequently undercooled δ phase remained even in a single γ phase region on the equilibrium phase diagram. Then, δ phase massively transformed to γ phase in the solid state (referred to as the massive-like transformation).…”

Section: Introductionmentioning

confidence: 99%

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Selection of the Massive-like δ-γ Transformation due to Nucleation of Metastable δ Phase in Fe-18 Mass%Cr-Ni Alloys with Ni Contents of 8, 11, 14 and 20 Mass%

et al. 2019

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Section: Introductionmentioning

confidence: 99%

“…[15][16][17] As far as the observations of solidification in Fe-C alloys are concerned, the massive-like transformation is a preferred transformation mode for the undercooled δ phase in carbon steel. The massive-like transformation 12,13) was characterized by following points:…”

Section: Introductionmentioning

confidence: 99%

Selection of the Massive-like δ-γ Transformation due to Nucleation of Metastable δ Phase in Fe-18 Mass%Cr-Ni Alloys with Ni Contents of 8, 11, 14 and 20 Mass%

et al. 2019

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“…The time-resolved and in-situ observations for steel 15,16) showed that the δ -γ transformation was proceeded by a massive-like transformation. The massive-like transformation was also confirmed by the observations with a confocal laser scanning microscope.…”

Section: Time-resolved and In-situ Observation Of δ -γ Transformationmentioning

confidence: 99%

“…[7][8][9][10][11] In addition, radiography has also been developed to observe solidification phenomena at temperatures above 1 500°C for Fe-based alloys. [12][13][14][15][16]…”

Section: Introductionmentioning

confidence: 99%

Time-resolved and In-situ Observation of δ–γ Transformation during Unidirectional Solidification in Fe–C Alloys

et al. 2020

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Time-resolved and in-situ observations using synchrotron radiation X-rays successfully proved that a massive-like transformation, in which the γ phase was produced through the solid-solid transformation and partitioning of substitute elements such as Mn and Si at the δ-γ interface was negligible, was selected in the unidirectional solidification of 0.3 mass% C steel at a pulling rate of 50 μm/s. The massive-like transformation produced fine γ grains near the front of the δ-γ interface. The coarse γ grains also grew behind the fine γ grains along the temperature gradient. Distance between the δ-γ front and the advancing front of coarse γ grains was as short as 200 μm. Namely, the fine γ grains disappeared within 10 s owing to growth of coarse γ grains. In addition, the observation of the δ-γ interface confirmed that a transition from the diffusion-controlled γ growth to the massive-like γ growth occurred at a growth velocity of 5 μm/s. Thus, the massive-like transformation is dominantly selected in the carbon steel during conventional solidification processes.

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“…In fact, recent in situ observations of the ¤/£ massive-like transformation with higher temporal resolution have revealed that not only the growing front of the £ phase is wavy but also its advancement is far from uniform, 45,46) implying a nucleation-controlled phase transformation.…”

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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

et al. 2015

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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 ¤/£, ¤/¤, and £/£ interfaces are 0.56, 0.44 and 0.37 J/m 2 , 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 £-phase nucleation in homogeneous ¤-phase matrix is more than three orders of magnitude greater than that for homogeneous solidification of ¤-phase, the £ nucleation on a ¤/¤ grain boundary in the solidifying matrix suppresses the energy barrier, increasing a nucleation rate. Furthermore, it is found that the £-phase nucleation on an existing £ nucleus halves undercooling needed with smaller critical radius. This suggests that, once £ nucleation is initiated, then following £ nucleation is promoted by doubled driving force, enabling multiple £ nucleation as in chain reaction. These findings are sufficient to explain experimentally observed phenomena during the ¤-£ massive-like phase transformation even if other factors such as solute re-distribution or transformation is neglected.

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Kinetics of the δ/γ interface in the massive-like transformation in Fe-0.3C-0.6Mn-0.3Si alloys

Cited by 22 publications

References 11 publications

Selection of the Massive-like <i>δ</i>-<i>γ</i> Transformation due to Nucleation of Metastable <i>δ</i> Phase in Fe-18 Mass%Cr-Ni Alloys with Ni Contents of 8, 11, 14 and 20 Mass%

Selection of the Massive-like <i>δ</i>-<i>γ</i> Transformation due to Nucleation of Metastable <i>δ</i> Phase in Fe-18 Mass%Cr-Ni Alloys with Ni Contents of 8, 11, 14 and 20 Mass%

Time-resolved and <i>In-situ</i> Observation of <i>δ</i>–<i>γ</i> Transformation during Unidirectional Solidification in Fe–C Alloys

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

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Kinetics of the δ/γ interface in the massive-like transformation in Fe-0.3C-0.6Mn-0.3Si alloys

Cited by 22 publications

References 11 publications

Selection of the Massive-like <i>δ</i>-<i>γ</i> Transformation due to Nucleation of Metastable <i>δ</i> Phase in Fe-18 Mass%Cr-Ni Alloys with Ni Contents of 8, 11, 14 and 20 Mass%

Selection of the Massive-like <i>δ</i>-<i>γ</i> Transformation due to Nucleation of Metastable <i>δ</i> Phase in Fe-18 Mass%Cr-Ni Alloys with Ni Contents of 8, 11, 14 and 20 Mass%

Time-resolved and <i>In-situ</i> Observation of <i>δ</i>–<i>γ</i> Transformation during Unidirectional Solidification in Fe–C Alloys

Concurrent &gamma;-Phase Nucleation as a Possible Mechanism of &delta;-&gamma; Massive-like Phase Transformation in Carbon Steel: Numerical Analysis Based on Effective Interface Energy

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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