General concept for a stability analysis of a planar interface under rapidsolidification conditions in multi-component alloy systems

Stability analysis of a growing planar solid/liquid interface is not only i mportant for predicting the limit of constitutional supercooling, V-C, or t he limit of absolute stability, V-abs, but also for the formulation of the so-called marginal stability criterion. This criterion is widely used as an approximate theory for dendritic growth. In this paper, a general concept is introduced which allows analysis of the stability of a planar solid/liqu id interface in technical, i.e. multi-component alloys. Capillarity and kin etic effects, and off-equilibrium thermodynamics are taken into account by solving an adequate non-linear system of equations. It is shown that dendri te tip radii and dendrite tip temperatures can be estimated as a function o f growth rate and temperature gradient for multi-component alloys. For this the solution of a second linear system of equations coming from the genera l stability analysis is necessary. (C) 2001 Published by Elsevier Science B .V.