The Influence of Gravity on the Solidification of Monotectic and Near Monotectic Cu-Pb Alloys

Bergman, Alexander; Carlberg, Torbjörn; Fredriksson, Hasse; Stjerndahl, J.

doi:10.1557/proc-9-579

Cited by 2 publications

(1 citation statement)

References 4 publications

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“…Rogers and Davis [1], Ratke [2] and Markworth and Gelles [3] treated the collision and coagulation statistics of droplets. Fredriksson and co-workers [4,5], Ahlborn et al [6] and Uebber and Ratke [7] have analysed the microstructure evolution in Zn-Bi, Al-In and Al-Pb and Zn-Pb respectively (for a recent overview see [8]). Just recently, Ratke and co-workers solved the problem of microstructure evolution under the common action of nucleation, growth and Stokes settlement for a system of constant temperature and constant supersaturation [9,10] and also for a cooling situation under reduced gravity conditions in which only thermocapillary or Marangoni motion instead of Stokes motion had to be considered [11,12].…”

Section: Introductionmentioning

confidence: 99%

Microstructure evolution of immiscible alloys during cooling through the miscibility gap

Zhao¹,

Ratke²,

Feuerbacher³

1998

Modelling Simul. Mater. Sci. Eng.

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A numerical model is developed describing the very fast process of microstructure evolution under the common action of nucleation and diffusional growth of minority phase droplets during cooling of a hypermonotectic alloy through the miscibility gap. The model is validated comparing it with an analytical solution obtained with some simplifying assumptions and then applied to predict the microstructure evolution in Al-Pb alloy in a real casting situation. The numerical model reflects the real physical processes well and also yields some general relations applicable to other immiscible alloys.

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Section: Introductionmentioning

confidence: 99%

Microstructure evolution of immiscible alloys during cooling through the miscibility gap

Zhao¹,

Ratke²,

Feuerbacher³

1998

Modelling Simul. Mater. Sci. Eng.

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The axisymmetric thermocapillary motion of a fluid particle in a tube

1991

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The thermocapillary migration of a fluid particle in a tube, owing to an imposed axial temperature gradient, is studied theoretically for the case of steady, axisymmetric, creeping, translation in the absence of thermal convection and fluid particle distortion from sphericity, and for an insulated tube. Formulated with these assumptions, the migration is a linear Stokes flow which is separable into two fixed-fluid particle flow idealizations. One is the fluid motion in a quiescent continuous phase, owing only to the thermocapillary surface stress. This stress causes fluid streaming which exerts a lift force on the fluid particle in the direction of the warmer fluid described by a lift coefficient. The second idealization is uniform flow in the absence of thermocapillary forces. The force on the fluid particle owing to this flow represents the hydrodynamic resistance to the forward motion of the fluid particle in the presence of the tube wall, and is described in terms of a drag coefficient. Numerical solutions for the lift and drag coefficients are obtained by a boundary collocation technique.The migration velocity in the tube relative to that under identical conditions in an infinite medium is computed from the ratio of the lift and drag coefficients. The calculations show that for a fixed ratio of the sphere to the tube diameter, as the conductivity of the fluid particle phase decreases relative to that of the continuous phase, a greater proportion of energy is conducted through the gap between the insulated tube wall and the fluid particle. This conduction pattern creates a larger surface temperature gradient, and causes the relative migration velocity to increase. The enhancement in migration for decreasing fluid particle conductivity at a fixed ratio of the sphere to the tube diameter becomes more pronounced as the later ratio increases and the surface gradient intensifies. However, as the gap distance between the sphere and the tube decreases, hydrodynamic retarding forces develop, and these forces are overriding in the sense that the relative migration velocity in the tube decreases monotonically from the value of one as the gap thickness decreases, and therefore the migration velocity in the tube never exceeds the value in an infinite medium.

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The Influence of Gravity on the Solidification of Monotectic and Near Monotectic Cu-Pb Alloys

Cited by 2 publications

References 4 publications

Microstructure evolution of immiscible alloys during cooling through the miscibility gap

Microstructure evolution of immiscible alloys during cooling through the miscibility gap

The axisymmetric thermocapillary motion of a fluid particle in a tube

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