Modelling of phase diagrams and thermodynamic properties using Calphad method – Development of thermodynamic databases

Abstract

The Calphad method is very important method for the modelling of thermodynamic properties and phase diagrams of multicomponent systems. The method is based on a semi-empirical approach and sequential modelling from simpler to more complicated systems. Therefore reliable experimental data are necessary for the description of the thermodynamic and phase properties of unary and binary systems. Basic principles of the method will be described in this paper, especially from the point of view of preparing the reliable theoretical thermodynamic description of simpler systems, which allow reliable prediction and assessment of higher order systems.The thermodynamic data, describing assessed binary and ternary systems are collected in the form of the thermodynamic databases, which allow (together with proper software) the prediction of properties for multicomponent systems corresponding to real materials. The software packages, based on Calphad method, are currently the only theoretical tools, applicable for complex materials as steels, superalloys, etc.The thermodynamic databases and outputs of the theoretical calculations are also important for many other applications and multi-scale simulations. They serve as input for phase field simulations, diffusion processes modelling, phase transformations, material properties and structure morphology development, including the processes on interface.