Connectivity of Phases and Growth Mechanisms in Peritectic Alloys Solidified at Low Speed: an X-Ray Tomography Study of Cu-Sn

Rappaz, M.; Kohler, F.; Valloton, J.; Phillion, A.B.; Stampanoni, Marco

doi:10.1007/s11661-009-0118-5

Cited by 18 publications

(10 citation statements)

References 29 publications

(15 reference statements)

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“…4). This observation confirms the overlay growth mechanism evidenced by Kohler et al [11,12,16]: a new band of a does not necessarily needs to nucleate ahead of b, even in a small capillary, but can start from another a part of the specimen which is not in the section plane. After these bands, the various colors of the numerous a-grains present in the matrix of b (which has transformed into an (a + d) eutectoid) reveal that they have different crystallographic orientations.…”

Section: General Features Of the Specimenssupporting

confidence: 88%

“…Using a liquid metal cooling (LMC) Bridgman solidification setup with quench, these authors observed all three of the peritectic microstructures discussed above -lamellae, bands and islands -but their sample showed appreciable convection. Using synchrotron-based X-ray microtomography, Rappaz et al [16] confirmed a new growth mechanism of bands: a-and b-phases can be totally interconnected in three dimensions and bands (or islands) can result from an overlay mechanism, rather than from subsequent nucleation events. When the lateral growth of a new layer is too fast, an instability can lead to the formation of a lamellar structure as for eutectic alloys.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

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Competition of the primary and peritectic phases in hypoperitectic Cu–Sn alloys solidified at low speed in a diffusive regime

2012

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This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. AbstractDirectional solidification experiments on hypoperitectic Cu-Sn alloys have been performed at very low velocity in a high thermal gradient to ensure planar front growth of both phases. The diameter of the sample has been reduced to 500 lm to strongly reduce convection. Lamellar and fibrous peritectic cooperative growth of the primary a-and peritectic b-phases has been observed on length spanning several millimeters. For the first time in a high solidification interval peritectic alloy, a quenched interface of both phases in contact with the liquid has been obtained. An unexpectedly high volume fraction of the primary phase, which furthermore fluctuates over time, has been observed. This is attributed to the transient state of the (a + b) growth front to a steady state and the associated evolution of the large diffusion layer ahead of the solid-liquid interface.

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Section: General Features Of the Specimenssupporting

confidence: 88%

Section: Theoretical Backgroundmentioning

confidence: 99%

Competition of the primary and peritectic phases in hypoperitectic Cu–Sn alloys solidified at low speed in a diffusive regime

2012

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“…In recent years, two lines of development have added new details to this picture. A series of experiments have been performed on the peritectic alloy Cu-Sn [73,74,75]. In comparison to the alloys studied previously, Cu-Sn has a much larger solidification interval, which implies that extremely low growth rates have to be used to avoid morphological instabilities.…”

Section: Peritecticsmentioning

confidence: 99%

“…In order to reduce solutal convection as much as possible, capillary tubes were used. The microstructures were analyzed using standard metallography, EBSD, as well as post mortem X-ray tomography [74] to obtain a three-dimensional view (see Fig. 5).…”

Section: Peritecticsmentioning

confidence: 99%

Eutectic and peritectic solidification patterns

Akamatsu

Plapp

2016

Current Opinion in Solid State and Materials Science

108

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International audienceRecent advances in the understanding of eutectic and peritectic two-phase pattern formation under purely diffusive transport are reviewed. The parallel progress of two key techniques, namely, in-situ experimentation with model, low-melting transparent and metallic alloys in thin and bulk samples, and numerical phase-field simulations, is highlighted. Experiments and simulations are interpreted in the light of the theory of non-equilibrium pattern formation phenomena. Focus is put on microstructure selection and morphological transitions, multiscale patterns in ternary alloys, and the influence of crystallographic effects on pattern formation. Open problems, for example on crystallographic effects, irregular eutectics, and peritectic solidification, are outlined

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“…Finally, it was found in experiments and by boundary integral simulations on the Fe-Ni system that coupled growth is stable only in certain ranges of concentrations and lamellar spacings [10]; at the boundary of this range, stable limit cycles of 1-k oscillations around the steady state were observed. Because of the limited stability, the initiation of coupled growth requires a non-trivial dynamical process, which generally leads to long transients before coupled growth emerges [8,17]. Since it is at present unknown how the stability conditions and the dynamics of the tran-sient depend on the characteristics of the phase diagram, more information on the initiation and stability of coupled growth in other alloy systems is needed.…”

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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Connectivity of Phases and Growth Mechanisms in Peritectic Alloys Solidified at Low Speed: an X-Ray Tomography Study of Cu-Sn

Cited by 18 publications

References 29 publications

Competition of the primary and peritectic phases in hypoperitectic Cu–Sn alloys solidified at low speed in a diffusive regime

Competition of the primary and peritectic phases in hypoperitectic Cu–Sn alloys solidified at low speed in a diffusive regime

Eutectic and peritectic solidification patterns

Modeling of peritectic coupled growth in Cu–Sn alloys

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