Transport modes during crystal growth in a centrifuge

Arnold, William A.; Wilcox, William R.; Carlson, F. M.; Chait, Arnon; Regel, L. L.

doi:10.1016/0022-0248(92)90201-s

Cited by 51 publications

(10 citation statements)

References 7 publications

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“…In general, the solution obtained this way will not satisfy Eq. (11). To obtain an estimate of the displacement between the interface and the melting-point isotherm, we use a first order Taylor's expansion of the temperature field about the current axial position of the interface, thereby obtaining…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Three-dimensional imperfections in a model vertical Bridgman growth system for cadmium zinc telluride

Yeckel

Compère

Pandy

et al. 2004

Journal of Crystal Growth

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Section: Methodsmentioning

confidence: 99%

“…Arnold et al [11] performed three-dimensional calculations to study semiconductor melt flows induced during a centrifugal crystal growth experiment. Yao and co-workers [12,13] considered threedimensional, steady-state heat transfer and flow during the horizontal Bridgman growth of succinonitrile.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional imperfections in a model vertical Bridgman growth system for cadmium zinc telluride

Yeckel

Compère

Pandy

et al. 2004

Journal of Crystal Growth

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“…More recently Sayre and Riahi [3] investigated non-oscillatory instabilities of the liquid and mushy regions during solidification of binary alloys under a high gravity environment, where it was assumed that the solidification system was placed in a centrifuge basket [4] whose rotation axis was inclined with respect to the high gravity vector. The high gravity vector was also assumed to be anti-parallel to the direction of the solidification growth rate.…”

Section: Introductionmentioning

confidence: 99%

Oscillatory instabilities of the liquid and mushy layers during solidification of alloys under rotational constraint

Sayre

Riahi

1997

Acta Mechanica

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Summary. Linear flow instabilities due to oscillatory disturbances of the liquid and mushy regions during solidification of binary alloys are investigated under a rotational constraint where the rotation axis is inclined to gravity vector. Results of stability analyses and numerical computations for a preferred centrifugal mode of general oscillatory disturbances at zero and non-zero rotation rates are determined which provide information about the preference of oscillatory flow and its role on the solidification system as modified by the rotational effects. The main results are due to a preferred oscillatory mode of convection which is more significant for non-zero rotation case and is restricted mostly to the mushy region. The preferred oscillatory mode of convection is a traveling wave in the presence of rotation, but it is a standing wave in the absence of rotation. The results for different Prandtl numbers indicate that the freckles formation tendency for metallic alloys is less than that for aqueous solutions. Freckles are imperfections that reduce the quality of the solidified materials.

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“…Secondly, the samples are mounted on a gondola with a free swing configuration, so that the plane of rotation of the sample is not horizontal, but parallel to the resultant of terrestrial gravity and centrifugal acceleration acting in the centre of gravity of the gondola. For these reasons, forecasting the outcome for a real case study including all these aspects is not trivial, since complex flow patterns, such as helicoidal ones [43], might develop in the samples. Therefore, the necessity of a further development of a 3D model is undeniable.…”

Section: Solidification On Centrifugementioning

confidence: 99%

Influence of natural and forced gravity conditions during directional columnar solidification

Battaglioli

Robinson

McFadden

2018

International Journal of Heat and Mass Transfer

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In a recent study, the present authors reported an analysis of a transient process of directional solidification of TiAl alloys in the absence of convection [Battaglioli et al., 2017]. The adopted front tracking model, also coupled with indirect methods for predicting columnar to equiaxed transition (CET), showed how the development of different grain regions, namely axial columnar, radial columnar and equiaxed, depends on process parameters such as temperature distribution and applied cooling rates, as well as on properties such as the degree of inoculation of the melt and nucleation undercooling required for equiaxed growth. In this paper, the previous front tracking model is significantly developed, by including the solution of Navier-Stokes equations in order to predict thermal convection in the liquid region as well as in the columnar mush (treated as an isotropic porous medium). This improvement is introduced with the aim to investigate TiAl alloys solidification under different gravity conditions. Accordingly, the simulation setup employed in the study reproduces the one used in experimental campaigns carried out on the MAXUS 9 sounding rocket (microgravity) and on ESA's Large Diameter Centrifuge (hypergravity), within the framework of ESA's GRADECET (Gravity Dependence of CET in TiAl alloys) project. The ability of the model in predicting thermal convection is demonstrated by considering several case studies. Results show that the evolution of fluid flow patterns in the samples depends on the external forces considered, combined to the transient change of axial and radial temperature gradients that occur during the solidification process. A parametric study of the directional solidification process on a centrifuge is performed by changing the value of the centrifuge arm and rotation rate and results are compared to predictions derived from nondimensional considerations.

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Transport modes during crystal growth in a centrifuge

Cited by 51 publications

References 7 publications

Three-dimensional imperfections in a model vertical Bridgman growth system for cadmium zinc telluride

Three-dimensional imperfections in a model vertical Bridgman growth system for cadmium zinc telluride

Oscillatory instabilities of the liquid and mushy layers during solidification of alloys under rotational constraint

Influence of natural and forced gravity conditions during directional columnar solidification

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