EXPERIMENTAL STUDY AND A THERMODYNAMIC EVALUATION OF THE Fe-Cr-Mo SYSTEM.

An experimental study of the Fe-Cr-Mo system has been made using a diffusion couple technique. Both ends of a large number of tie-lines have been determined using both an electron microprobe and a scanning electron microscope with energy dispersive X-ray analysis equipment. The isothermal sections at 1223, 1273, 1373, and 1473 K have been constructed from the experimental data and thermodynamic model calculations. The Gibbs energy of the intermetallic phases has been described with a recently developed model for phases with several sublattices. The parameter values describing the Gibbs energy of each individual phase were determined with a computerized optimization technique. The calculated phase diagrams are in satisfactory agreement with the experimental information and allow reasonable extrapolation outside the experimental temperature range.