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Proceedings Paper

Effects of gravity on the double-diffusive convection during directional solidification of a nondilute alloy with application to HgCdTe
Author(s): Andris V. Bune; Donald C. Gillies; Sandor L. Lehoczky
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Paper Abstract

A general 2D and 3D finite element model of non-dilute alloy solidification was used to simulate growth of HgCdTe in terrestrial and microgravity conditions. Verification of the 3D model was undertaken by comparison with previously published result on convection in an inclined cylinder. For low growth velocities, plane front solidification occurs. The location and the shape of the interface were determined using melting temperatures obtained from the HgCdTe liquids curve. The low thermal conductivity of the solid HgCdTe causes a thermal short circuit through the ampoule walls, resulting in curved isotherms in the vicinity of the interface. Double-diffusive convection in the melt is caused by radial temperature gradients and by material density inversion due to the combined effects of composition and temperature. Cooling from below and the rejection at the solid-melt interface of the heavier HgTe-rich solute each tend to reduce convection. Because of these complicating factors, dimensional rather than non-dimensional modeling was performed. The predicted interface shape is in agreement with one obtained experimentally by quenching.

Paper Details

Date Published: 6 July 1999
PDF: 6 pages
Proc. SPIE 3792, Materials Research in Low Gravity II, (6 July 1999); doi: 10.1117/12.351276
Show Author Affiliations
Andris V. Bune, Universities' Space Research Association (United States)
Donald C. Gillies, NASA Marshall Space Flight Ctr. (United States)
Sandor L. Lehoczky, NASA Marshall Space Flight Ctr. (United States)

Published in SPIE Proceedings Vol. 3792:
Materials Research in Low Gravity II
Narayanan Ramachandran, Editor(s)

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