A thermodynamic database for Ni-base superalloys

A thermodynamic database has been developed for Ni-base superalloys. Follow ing the CALPHAD procedure, it is based on the assessment of thermodynamic b ehaviour 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 s ingle Gibbs energy function taking into account the crystallographic relati on between these two phases. The formalism of the thermodynamic models used is briefly introduced. A few phase diagrams calculated with the current da tabase in assessed binary and ternary systems are presented. Some experimen ts available in higher order systems are compared with the results of calcu lations with the current database. The ability of extrapolation of the data base is verified for solid state equilibria as well as for solidification b ehaviour (liquidus temperature and partition ratios). The introduction of M o and Ta to the current database is in progress. Other elements (Nb, Fe, Zr , Hf, C, B, . . .) are planed to be introduced.