Partial Differential Equations and Continuum Models of Phase Transitions (Equations aux Derivees Partielles et Modeles Continus de Transitions de Phases).

摘要

Experimental data are analyzed by the light of recent enlightning diffusive theories for the selection of morphological patterns (cells or dendrites) during directional solidification of binary alloys. It is shown that a new unifying formulation of the dispersed available values for the shape parameters naturally appears, which depends only on the segregation coefficient k of solute. Fluid flow in the melt results in a shift from the diffusive branch. By introducing the concept of a diffusive boundary layer ahead of the front, which can be characterized either by its thickness delta or by the effective partition coefficient keff, it is shown how the shape parameters are affected by convection. (JES)