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.


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    Titel :

    Melt convection effects in the Bridgman crystal growth of an alloy under microgravity conditions


    Beteiligte:
    Simpson, J.E. (Autor:in) / Garimella, S.V. (Autor:in) / Groh, H.C. III de (Autor:in) / Abbaschian, R. (Autor:in)


    Erscheinungsdatum :

    1998


    Format / Umfang :

    10 Seiten, 16 Quellen


    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Print


    Sprache :

    Englisch




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