Stability and selection of lamellar eutectic growth with anisotropic surface tension

Abstract

The morphological stability of lamellar eutectic growth with the anisotropic effect of surface tension is studied by means of the interfacial wave (IFW) theory developed by Xu in the 1990s. We solve the related linear eigenvalue problem for the case that the Peclet number is small and the segregation coefficient parameter is close to the unit. The stability criterion of lamellar eutectic growth with the anisotropic surface tension is obtained. The linear stability analysis reveals that the stability of lamellar eutectic growth depends on a stability critical number [Formula: see text]. Similar to the case of isotropic surface tension, the system involves two types of global instability mechanisms: the “exchange of stability” invoked by the non-oscillatory, unstable modes and the “global wave instabilities” invoked by four types of oscillatory unstable modes, namely antisymmetric–antisymmetric (AA-), symmetric–symmetric (SS-), antisymmetric–symmetric (AS-) and symmetric–antisymmetric (SA-) modes. The anisotropic surface tension, by decreasing the corresponding stability critical number [Formula: see text], stabilizes the “exchange of stability” mechanism and “global wave instability” mechanism invoked by AA-, SA- and SS-modes. However, by increasing the corresponding stability critical number [Formula: see text], the anisotropic surface tension destabilizes the “global wave instability” mechanism invoked by AS-mode.