COMPUTATION OF PHASE-EQUILIBRIA IN THE FE-NI-CR SYSTEM BASED UPON MASS-SPECTROMETRIC INVESTIGATIONS

Phase diagram calculations require only the differences between the ch emical potentials of the involved phases. This makes it possible to us e even artificial thermodynamic parameter sets which then have to be c orrected by means of additional terms. It is demonstrated that mass sp ectrometric investigations yield a simpler, but more effective algebra ic description of the thermodynamic ternary mixing behavior than the r esults of previous phase diagram assessments: mass spectrometric measu rements in the liquid phase, and in the restricted field of fee-phase in the system Fe-Ni-Cr together with the algebraic descriptions of the three binary boundary systems Fe-Ni, Ni-Cr, and Cr-Fe as reported in previous works make it possible to compute ternary phase equilibria in the system Fe-Ni-Cr, showing better agreement with the experimental p hase equilibria data than the assessments as reported by Kundrat and E lliot, Hillert and Qiu, and Lee. Additional advantage of the mass spec trometric determined molar Gibbs energy is that the description of the magnetic contributions Z(k)(alpha,mag)(T,x(alpha)) has been merely re duced to the expressions of the pure species. (C) 1998 Elsevier Scienc e B.V.