Time dependent interface stability during rapid solidification

The destabilization of a planar solid/liquid interface during resolidificat ion of the molten surface layer of Si-Sn alloys is investigated. Experiment al data are compared with the results of a transient numerical stability an alysis. In that analysis the time evolution of an infinitesimal sinusoidal perturbation of a planar interface is investigated. For this the concentrat ion profile in the melt as well as the temperature distributions in the mel t and solid are divided into a base state and a state due to the perturbati on. The highly nonuniform Sn profiles implanted in (100) silicon samples se rve as initial conditions for the numerical calculations. Deviations from t hermal equilibrium at the solid/liquid interface are considered. The critic al concentration for breakdown is calculated as a function of solidificatio n velocity and compared with the results of the analytical analysis of Hunt ley and Davis [Acta Metall. Mater. 41, 2025 (1993)]. It is further investig ated whether an analytical steady-state stability analysis can be used to a pproximately describe the experiments considered. (C) 1999 American Institu te of Physics. [S0021- 8979(99)00620-9].