Phase and microstructure selection in peritectic alloys close to the limit of constitutional undercooling

Hunziker, O.; Vandyoussefi, M.; Kurz, W.

doi:10.1016/s1359-6454(98)00336-x

Cited by 104 publications

(57 citation statements)

References 11 publications

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“…As mentioned in Ref. 13), the phase transition is supposed to occur only when the nucleation can occur ahead of the growing phase, assuming that the volume ahead of the growing interface is rapidly filled with the nucleating phase with a high nucleation density and growth rate. Reference has also been made to the columnar-to-equiaxed transition in casting and rapid solidification processes 22) which are also induced by the constitutional undercooling ahead of the growing front.…”

Section: Nucleation Conditionsmentioning

confidence: 99%

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Band Structure Formation in Peritectic Fe-Co and Fe-Ni Alloys

Sumida

2003

Mater. Trans.

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In this paper, band structure formation in peritectic Fe-18.0 at%Co and Fe-4.4 at%Ni alloys is reported. Bridgman type directional solidification experiments were performed, and an island band structure was observed in both of these alloys under low velocity solidification conditions. Solid composition profiles along the growth direction in this band region were determined with electron probe measurements. The solute concentration increased during growth, and after an abrupt increase for phase change, it decreased during growth. It then decreased abruptly for the phase change to . Repetition of this process formed bands. Composition profiles calculated by the convection model were compared with these experimental results, suggesting that island bands form by a mechanism similar to that assumed in the model for discrete bands. Furthermore, the nucleation condition in this model was extended. Applying the nucleation constitutional undercooling criterion, a new calculation was developed. The mechanism of band structure formation is discussed in the light of these results.

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Section: Nucleation Conditionsmentioning

confidence: 99%

“…Furthermore, the nucleation condition in this model was extended. The nucleation constitutional undercooling criterion 13) is adopted for creation of a new solid in front of a growing interface. A new calculation is developed, and its results are compared with those of the convection and diffusion models.…”

Section: Introductionmentioning

confidence: 99%

Band Structure Formation in Peritectic Fe-Co and Fe-Ni Alloys

Sumida

2003

Mater. Trans.

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“…This increased velocity may lead to changes in solidification morphology, partitioning, and primary phase selections. [44][45][46][47][48][49] In welds, epitaxial solidification occurs from the heat-affected-zone, the nucleation of solid phase occurs readily.…”

Section: Rapidly Cooled Weld Microstructurementioning

confidence: 99%

Inclusion Formation and Microstructure Evolution in Low Alloy Steel Welds.

Babu

David

2002

ISIJ International

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The paper presents an overview of research performed at Oak Ridge National Laboratory on inclusion-formation, weld-solidification, and solid-state transformations in low-alloy steel welds. The competition between oxide and nitride formation in Fe-C-Al-Mn self-shielded flux-cored arc steel welds was predicted using computational thermodynamics. Nonequilibrium austenite phase selection was monitored in a Fe-CAl-Mn weld using an in situ time-resolved X-ray diffraction technique. The competition between acicular ferrite and bainite formation from austenite was evaluated in Fe-C-Mn steel welds containing small amounts of titanium.KEY WORDS: steel welds; inclusion formation; weld solidification; nonequilibrium phase transformations; bainite; acicular ferrite.

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“…These alloys show a wide variety of microstructures in directional solidification at low speed [1][2][3][4][5][6][7][8][9][10][11][12][13], including regions of primary a, primary b, islands of one phase in the other and coupled growth. It is this latter microstructure that is of most interest here.…”

Section: Introductionmentioning

confidence: 99%

Modeling of peritectic coupled growth in Cu–Sn alloys

Valloton¹,

Dantzig²,

Plapp³

et al. 2013

Acta Materialia

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In directional solidification experiments on hypoperitectic Cu-Sn alloys at low velocity and high thermal gradient, both lamellar and fibrous coupled peritectic growth patterns have been observed. Two phenomena that had not been observed in previous experiments on other alloy systems are investigated here with the help of different modeling approaches. The mean volume fraction of primary phase a, g a , as determined by X-ray microtomography, decreases with solidification distance over the entire length of the coupled zone, but is always much larger than that expected from the equilibrium phase diagram. Moreover, oscillations in g a with a spatial periodicity approximately equal to the lamellar spacing are also observed. The first observation is explained semi-quantitatively by a simple 1D diffusion model, which reveals that the onset of coupled growth occurs during the initial transient of the primary phase planar front growth. A two-dimensional phase-field model is used to monitor the subsequent microstructure evolution, and shows that the lamellar structure exhibits collective 1-k oscillations. In agreement with previous studies, it was found that these oscillations lead to stable coupled growth only for a limited range of the control parameters.

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Phase and microstructure selection in peritectic alloys close to the limit of constitutional undercooling

Cited by 104 publications

References 11 publications

Band Structure Formation in Peritectic Fe-Co and Fe-Ni Alloys

Band Structure Formation in Peritectic Fe-Co and Fe-Ni Alloys

Inclusion Formation and Microstructure Evolution in Low Alloy Steel Welds.

Modeling of peritectic coupled growth in Cu–Sn alloys

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