Session CC - Material Processing.
ORAL session, Sunday afternoon, November 24
Room 1, OnCenter
The cooling and solidification of liquid metal drops falling inside a tube filled with an inert gas have been modeled. Solidification was initiated by homogeneous nucleation, which reflects the containerless conditions. Since the homogeneous nucleation rate is very sensitive to the degree of undercooling, it is important to know precisely the temperature distribution and temperature evolution in the metal drop. The cooling of the drop was modeled using a semi-analytical method and the heat flow in the drop after nucleation was modeled using Green's functions. A relationship was established between the cooling history of the molten drop, i.e.\ the degree of undercooling, and the number of nuclei (proportional to the number of crystals) in the drop after solidification. Since the nucleation rate strongly depends on the solid-liquid interfacial tension, it is possible to establish an upper limiting value for this quantity from comparisons with experiments.