par Van Vaerenbergh, Stefan 
;Legros, Jean Claude ;Hennenberg, Marcel
Référence Journal of crystal growth, 158, 3, page (369-376)
Publication Publié, 1996
;Legros, Jean Claude ;Hennenberg, Marcel Référence Journal of crystal growth, 158, 3, page (369-376)
Publication Publié, 1996
Article révisé par les pairs
| Résumé : | The planar growth of directional solidification from a binary melt is analyzed taking into account thermodiffusive transport. Both stable and overstable planar growth regimes are considered in the case of dilute alloys and as far as convective process does not modify the extent of the solute transition zone (the diffusion boundary layer) that appears in the absence of convection. Under such conditions, thermodiffusion appears as a thermophoretic transport process. The extent of the diffusion boundary layer is divided by a factor μc = 1 + DTGl/V, where DT is the thermodiffusion coefficient, Gl the interface thermal gradient in the melt and V the growth rate. The solute profile is modified accordingly. Planar overstable modes under the form of striations, are predicted. They appear with a period of the order of the ratio of the isothermal diffusion coefficient divided by the square of the growth rate. Such instabilities are expected in constitutionally supercooled melts for systems with large positive liquidus slopes and Soret coefficient for a threshold value of the solute concentration. |
