THE EFFECT OF ANISOTROPIC SURFACE TENSION ON THE LAMELLAR EUTECTIC GROWTH IN DIRECTIONAL SOLIDIFICATION

For the case of small interlamellar spacing relative to the solute diffusion length, the steady spatially periodic lamellar eutectic growth with the anisotropic effect of surface tension in directional solidification is studied by the approach of the interfacial wave (IFW) theory. The anisotropic surface tension is expressed as the fourfold symmetric function. We obtained a family of the uniformly valid asymptotic solutions for the steady lamellar eutectic growth and determined the corresponding interfacial patterns affected by anisotropic surface tension. The analytical solution reveals the anisotropic effect of surface tension on the interface shape of lamellar eutectic growth near the triple point. The temperature distribution at the interface shows a noticeable nonuniformity and there is a thin boundary layer for temperature and concentration near the triple point. As the anisotropic surface tension increases, the interface temperature away from the triple-point increases, whereas near the triple point the interface temperature decreases. Compared with the lamellar eutectic growth with isotropic surface tension, the anisotropic surface tension changes the position of the triple point and accelerates the growth of the lamellar eutectic. The theoretical prediction shows quantitatively consistent with recent experimental data without making any artificial adjustments to parameters.