Experiments on Dendrite Branch Detachment in the Succinonitrile-Camphor Alloy

Sato, Takeshi; Kurz, W.; Ikawa, Katsuya

doi:10.2320/matertrans1960.28.1012

Cited by 49 publications

(42 citation statements)

References 10 publications

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“…The detail for this method has been described in the literature. 10,11) A CCD camera is attached to the optical microscope and in-situ observation of the solidification of organic materials is made and the morphology of the unidirectional solidification is recorded by a DVD recorder. The most part of the alloy in the glass cell is melted and unidirectional solidification is performed from the solid phase.…”

Section: Methodsmentioning

confidence: 99%

Effect of Anisotropy of Surface Energy on the Growth Direction of Solid Phase in Constrained Growth Condition

et al. 2005

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The growth direction of solid phase, which has a great influence on the grain selection, has been investigated. Transparent organic systems, succinonitrile-H 2 O alloy and pivalic acid-H 2 O alloy have been used for unidirectional solidification. Essential parameters of phase diagrams, distribution coefficient of H 2 O (k) and liquidus slope (m) have been determined experimentally. The relationship is analyzed between dimensionless growth velocity (V=V c , where V c is the critical growth velocity for constitutional supercooling) and dimensionless growth direction ( 0 ). The change in 0 with V=V c is common and similar for both alloy systems. 0 increases rapidly at low growth velocity region. Then, 0 increases slowly and approaches unity with increasing V=V c . When the anisotropy of surface energy increases, the growth direction of solid phase becomes close to the preferred growth direction even at low growth velocity region, where cellular interface is observed.

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Section: Methodsmentioning

confidence: 99%

Effect of Anisotropy of Surface Energy on the Growth Direction of Solid Phase in Constrained Growth Condition

et al. 2005

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“…There may be two mechanisms for detachment. First, the fluctuations of temperature and/or concentration fields affect this process as pointed by Sato et al 17) Secondly, the flow directly breaks the secondary dendrite arms mechanicaly. 18) As mentioned before, the forced convection induced by the rotor seems not to affect the movement of pre-equiaxed grains.…”

Section: Development To the Equiaxed Dendritesmentioning

confidence: 99%

Origin of Equiaxed Grains and their Motion in the Liquid Phase

et al. 2003

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In order to investigate the multiplication of equiaxed grains by the forced convection, in-situ observation using a transparent organic substance have been made. The emission of some spherical particles from the columnar zone was observed by a fiber scope installed in an ingot case. These particles are originally the secondary dendrite arms and are detached by the fluctuations of thermal and/or solutal fields and/or mechanical breaking. Then the particles fell down in the liquid along with the natural convection. This event has taken place approximately 30 s before the well-developed equiaxed grains started to form. Therefore, these particles developed to equiaxed dendrites floating around in the liquid.A physical model for formation of equiaxed grains based on the observation has been proposed. The experimental results on the change in multiplication rate with time could be reasonably explained by this physical model.

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“…[27] The large velocity growth will provide a large tip undercooling and creates thinner secondary arms with finer arm neck, consequently these structures are more prone to remelt, than a coarser arm neck. Higher growth rate will also create larger number of secondary arms, thus the condition to enable detachment is increased.…”

Section: ½10mentioning

confidence: 99%

“…For the lower concentration group (27,27.58, and 28 wt pct), solidification started around 25 minutes after cooling from 315.15 K was initiated. The solid appeared along the lateral walls first, under small islands, which developed further until they completely covered the 3 cell's walls (side and bottom walls).…”

Section: Flow and Solidification Stagesmentioning

confidence: 99%

On the Coupling Mechanism of Equiaxed Crystal Generation with the Liquid Flow Driven by Natural Convection During Solidification

Stefan-Kharicha

Kharicha

et al. 2018

Metall Mater Trans A

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The influence of the melt flow on the solidification structure is bilateral. The flow plays an important role in the solidification pattern, via the heat transfer, grain distribution, and segregations. On the other hand, the crystal structure, columnar or equiaxed, impacts the flow, via the thermosolutal convection, the drag force applied by the crystals on the melt flow, etc. As the aim of this research was to further explore the solidification-flow interaction, experiments were conducted in a cast cell (95 * 95 * 30 mm 3 ), in which an ammonium chloride-water solution (between 27 and 31 wt pct NH 4 Cl) was observed as it solidified. The kinetic energy (KE) of the flow and the average flow velocity were calculated throughout the process. Measurements of the volume extension of the mush in the cell and the velocity of the solid front were also taken during the solidification experiment. During the mainly columnar experiments (8 cm liquid height) the flow KE continuously decreased over time. However, during the later series of experiments at higher liquid height (9.5 cm), the flow KE evolution presented a strong peak shortly after the start of solidification. This increase in the total flow KE correlated with the presence of falling equiaxed crystals. Generally, a clear correlation between the strength of the flow and the occurrence of equiaxed crystals was evident. The analysis of the results strongly suggests a fragmentation origin of equiaxed crystals appearing in the melt. The transition from purely columnar growth to a strongly equiaxed rain (CET) was found to be triggered by (a) the magnitude of the coupling between the flow intensity driven by the equiaxed crystals, and (b) the release and transport of the fragments by the same flow recirculating within the mushy zone. Graphical AbstractMIHAELA STEFAN-KHARICHA, ABDELLAH KHARICHA, MENGHUAI WU, and ANDREAS LUDWIG are with the

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Experiments on Dendrite Branch Detachment in the Succinonitrile-Camphor Alloy

Cited by 49 publications

References 10 publications

Effect of Anisotropy of Surface Energy on the Growth Direction of Solid Phase in Constrained Growth Condition

Effect of Anisotropy of Surface Energy on the Growth Direction of Solid Phase in Constrained Growth Condition

Origin of Equiaxed Grains and their Motion in the Liquid Phase

On the Coupling Mechanism of Equiaxed Crystal Generation with the Liquid Flow Driven by Natural Convection During Solidification

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