"Nucleation When Diffusion Becomes Important: A Tale of Two Fluxes"Professor Ken Kelton , Department of Physics - Washington University [Host: Joseph Poon]
ABSTRACT:
The classical theory of nucleation does not properly describe nucleation
processes when long-range diffusion becomes competitive with the
interfacial processes. A new model is presented for time-dependent
homogeneous nucleation in condensed phases, which takes account of the
coupled fluxes of interfacial attachment and long-range diffusion.
Numerical solutions from this new model show that the time-dependent
nucleation rates scale with the dominant mobility and that the
steady-state rates and induction times frequently differ significantly
from values predicted by the classical theory. Surprisingly, the
composition of the region of the parent phase near sub-critical crystal
clusters is shifted toward that of the new phase. Consequences are
discussed for solid state precipitation and the crystallization of
Al-rare earth metallic glasses.
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Condensed Matter Seminar Thursday, October 12, 2000 4:00 PM Physics Building, Room 204 Note special time. Note special room. |
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