A thermodynamic database for Ni-base superalloys

A thermodynamic database has been developed for Ni-base superalloys. Following the CALPHAD procedure, it is based on the assessment of thermodynamic behaviour of the relevant constituting sub-systems of the complex system of interest. The current database contains 7 elements: Al, Co, Cr, Ni, Ti, W, Re. The thermodynamics of the gamma and gamma' phases are modelled with a single Gibbs energy function taking into account the crystallographic relation between these two phases. The formalism of the thermodynamic models used is briefly introduced. A few phase diagrams calculated with the current database in assessed binary and ternary systems are presented. Some experiments available in higher order systems are compared with the results of calculations with the current database. The ability of extrapolation of the database is verified for solid state equilibria as well as for solidification behaviour (liquidus temperature and partition ratios). The introduction of Mo and Ta to the current database is in progress. Other elements (Nb, Fe, Zr, Hf, C, B, . . .) are planed to be introduced.