Mesoscopic kinetics of nonequilibrium solidification

Disadvantages of Aziz interface partition model [J. Appl. Phys. 53, 1158 (1 982)] are summarized in this article. Using transition state theory and Max well-Boltzmann distribution law, a mesoscopic solute partition model (MPM) including multilayer interface for dilute solution is put forward. It is sh own that the static interface structure and roughening behavior have signif icant effects on solute partitioning. Both the partition processes of semic onductors and metals can be explained by MPM rationally. The Aziz model is just a particular case of MPM for monolayer interface without roughening be fore complete trapping occurs. Comparisons of MPM with experimental results in Si (As, Ge, Bi, Sn) and Al(Cu, Sn, Ge, In) show pretty good agreement, provided an educated speculation of interface roughening behavior is given. Also in MPM, it is pointed out that interface diffusivity D-i correlates w ith the interface scale. For semiconductors with an atomic sharp solid/liqu id interface, D-i is close to D-L, the diffusivity of bulk liquid. On the o ther hand, for metals with a diffuse interface, D-i can be orders of magnit ude lower than D-L, to some extent estimated by root DSDL, the geometric me an of the diffusivity of bulk solid and liquid. (C) 2000 American Institute of Physics. [S0021-8979(00)05411-6].