Oscillatory morphological stability for rapid directional solidification: Effect of non-linear liquidus and solidus

Incorporating the effect of non-linear liquidus and solidus, an extended morphological stability model, in which both steady cellular and oscillatory modes are considered, was developed for rapid directional solidification. In the modeling, both the solid/liquid interface and the bulk liquid are under local non-equilibrium conditions. The oscillatory mode was analyzed to obtain a general oscillatory absolute stability from which six different models for the oscillatory absolute stability were proposed by adopting different interface kinetic models. A comparative study in Ag-Cu alloys showed that the effect of non-linear liquidus and solidus plays an important role and thus must be considered in the oscillatory stability of a planar interface.