Modeling temperature and concentration dependent solid/liquid interfacial energiesWednesday (28.09.2016) 10:15 - 10:30 Part of:
Microstructural evolution during solidification is strongly influenced by the solid/liquid interfacial energy, which thus has a direct impact on the materials properties. Despite its importance, experimental methods for the determination of the interfacial energy are limited to pure substances (maximum supercooling experiments ) or eutectic alloys (dihedral angle  or grain boundary groove method ). The temperature and concentration dependence of the solid/liquid interfacial energy are generally not determined when applying these experimental methods. During solidification of alloys, the temperature of the interface and thus the concentration of the solid and liquid phase at the interface vary with time. If the variation of the interfacial energy during solidification is to be considered, it is at present only accessible by modeling. Models for the prediction of the interfacial energy require the melting enthalpy (e.g. Turnbull ) and/or the melting entropy (Gránásy ) and/or the mixing entropy (Miedema ) as input parameter. For the calculation of temperature and concentration dependent interfacial energies, the change of these thermodynamic entities needs to be considered. CALPHAD-type thermodynamic databases offer the possibility to introduce temperature and concentration dependent values for the calculation of the solid/liquid interfacial energy of alloys in the entire temperature range between liquidus and solidus. Under the assumption of local equilibrium at the solid/liquid interface, different models of the interfacial energy for binary alloys from the literature are extended and employed to calculate the temperature and concentration dependent interfacial energy of binary and multicomponent solid solutions or intermetallic phases, respectively, with their respective liquids. 
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