The solidification of a dilute alloy (bismuth-tin) under Bridgman crystal growth conditions is investigated in support of NASA's MEPHISTO space shuttle flight experiment. Computations are performed in two-dimensions with a uniform grid. The simulation includes the species-concentration, temperature and flow fields, as well as conduction in the ampoule. Fully transient simulations have been performed; no simplifying steady state approximations are used. Results are obtained under microgravity conditions for pure bismuth, and Bi-0.1 at.%Sn and Bi-1.0 at.%Sn alloys. The concentration dependence of the melting temperature is neglected; the solid/liquid interface temperature is assumed to be the melting temperature of pure bismuth for all cases studied. For the Bi-1.0at.%Sn case the results indicate that a secondary convective cell, driven by solutal gradients, forms near the interface. The magnitude of the velocities in this cell increases with time; this causes increasing solute segregation at the solid/liquid interface.
Melt convection effects in the Bridgman crystal growth of an alloy under microgravity conditions
1998
10 Seiten, 16 Quellen
Aufsatz (Konferenz)
Englisch
Study of Bridgman Crystal Growth Process under Microgravity
British Library Conference Proceedings | 1994
|Stability of melt crystal growth under microgravity conditions
Elsevier | 1991
|British Library Conference Proceedings | 2000
|Crystal growth of GaSb under microgravity conditions
Elsevier | 1983
|Thermocapillary Convection Instability in Microgravity Crystal Growth
British Library Online Contents | 1992
|