| This theoretical study was carried out on the determination of the morphological stability criterion of planar solid-liquid interface. The system of a directional solidification under the nonequilibrium steady-state was defined as a continuous open system and the basic assumptions for the perturbation on the planar interface were introduced in order to analyze the pattern formation. The pattern formation was also interpreted by applying the marginal stability hypothesis. The results obtained can be summarized as follows. 1. The morphological stability criterion was T_mΓω²+ G_L-mG_c $gt; 0 and this could be reduced to the CS criterion. 2. The critical wavelength of perturbation, λ_c, was calculated by applying the marginal stability. From this result, it could be predicted that the shapes of the interface were changed with the wave length of perturbation. 3. It was suggested that the cell size, ℓ, can be limited by the critical wavelength of perturbation. |
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