Space flight data from the Isothermal Dendritic Growth Experiment

Glicksman, M.E.; Koss, M. B.; Bushnell, L.T.; LaCombe, J. C.; Winsa, E.

doi:10.1016/0273-1177(95)00156-9

Cited by 9 publications

(4 citation statements)

References 12 publications

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“…For a better comparison with these theories, a series of experiments called the Isolated Dendritic Growth Experiment (IDGE) were conducted during flights of the Space Shuttle [5][6][7][8]. For practical purposes (low melting point, transparent), pure succinonitrile (SCN) was used in many of these crystallization experiments.…”

Section: Introductionmentioning

confidence: 99%

Effects of nonlinear interfacial kinetics and interfacial thermal resistance in planar solidification

2012

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Large temperature discontinuities were recently measured at a solid-liquid interface during heat transport processes. These observations suggest that when heat flows between two phases, the interface is not well characterized by assuming thermal equilibrium. This can be of importance in rapid solidification processes. In this paper we consider a planar front model that solidifies from its undercooled melt. We use a generalized interfacial boundary condition that includes nonlinear kinetic effects and allows for a temperature discontinuity. The effects of the new boundary condition on the solidification rates and the temperature profile are reported as a function of time. Our analysis shows that the undercooling regime where constant phase-front velocities are observed at steady states (traveling-wave solutions) are unaffected by the new boundary conditions. These solutions arise when the Stephan number is larger than 1. On the other hand, the solidification rates and the steady-state velocities are greatly affected by the assumed conditions at the interface. Incorporation of an interface thermal resistance, or Kapitza resistance, generates temperature discontinuities at the interface, leads to reduced solidification rates and the Mullins-Sekerka instability arises at longer wavelengths deformation of the planar front.

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Section: Introductionmentioning

confidence: 99%

Effects of nonlinear interfacial kinetics and interfacial thermal resistance in planar solidification

2012

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“…USMP-2, À3, and À4 collectively yielded growth kinetic and morphological data on ultra-pure SCN and PVA from more than 350 experiments. [43] Low-earth orbit (LEO) provides a nearly ideal microgravity environment that eliminates all vestiges of buoyant, or natural, convection in the melt during solidification.…”

Section: E Testing Current Theories Of Dendritic Growthmentioning

confidence: 99%

Mechanism of Dendritic Branching

Glicksman

2011

Metall Mater Trans A

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Theories of dendritic growth currently ascribe pattern details to extrinsic perturbations or other stochastic causalities, such as selective amplification of noise and marginal stability. These theories apply capillarity physics as a boundary condition on the transport fields in the melt that conduct the latent heat and/or move solute rejected during solidification. Predictions based on these theories conflict with the best quantitative experiments on model solidification systems. Moreover, neither the observed branching patterns nor other characteristics of dendrites formed in different molten materials are distinguished by these approaches, making their integration with casting and microstructure models of limited value. The case of solidification from a pure melt is reexamined, allowing instead the capillary temperature distribution along a prescribed sharp interface to act as a weak energy field. As such, the Gibbs-Thomson equilibrium temperature is shown to be much more than a boundary condition on the transport field; it acts, in fact, as an independent energy field during crystal growth and produces profound effects not recognized heretofore. Specifically, one may determine by energy conservation that weak normal fluxes are released along the interface, which either increase or decrease slightly the local rate of freezing. Those responses initiate rotation of the interface at specific locations determined by the surface energy and the shape. Interface rotations with proper chirality, or rotation sense, couple to the external transport field and amplify locally as side branches. A precision integral equation solver confirms through dynamic simulations that interface rotation occurs at the predicted locations. Rotations points repeat episodically as a pattern evolves until the dendrite assumes a dynamic shape allowing a synchronous limit cycle, from which the classic repeating dendritic pattern develops. Interface rotation is the fundamental mechanism responsible for dendritic branching.

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“…Consequently, experiments have been designed to suppress natural convection under microgravity conditions [1] or by using thin samples [2]. Dendritic growth under pure diffusive conditions has been experimentally and numerically studied [3][4][5][6][7]. The effect of natural convection on dendritic growth was investigated in experiments [8,9] and simulations [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Columnar dendritic solidification of TiAl under diffusive and hypergravity conditions investigated by phase-field simulations

Viardin

Zollinger

Sturz

et al. 2020

Computational Materials Science

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Based on 2D phase-field simulations including fluid flow driven by natural convection, columnar dendritic growth of the β-solidifying Ti-48 at%Al alloy is characterised for different gravity levels ranging from 0 to ±15g. Depending on the direction of the gravity g with respect to the growth direction, different flow regimes emerge which show stable or unstable dendritic growth dynamics. When gravity and growth directions are parallel, the dendrite tips experience downward melt flow and individual dendrites grow in a stable manner with a rather small modification of the operating state. When gravity and growth directions are antiparallel, the impact on the operating state is larger. Eventually, at higher gravity levels the upward melt flow around the dendrite tips "destabilises" the dendritic morphology resulting in tip splitting, branching and local changes in the apparent dendrite growth direction which is an alternative mechanism for the adjustment of the primary dendrite arm spacing in addition to tertiary arm formation.

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Space flight data from the Isothermal Dendritic Growth Experiment

Cited by 9 publications

References 12 publications

Effects of nonlinear interfacial kinetics and interfacial thermal resistance in planar solidification

Effects of nonlinear interfacial kinetics and interfacial thermal resistance in planar solidification

Mechanism of Dendritic Branching

Columnar dendritic solidification of TiAl under diffusive and hypergravity conditions investigated by phase-field simulations

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