THERMODYNAMIC ACTIVITIES AND PARTIAL ENTHALPIES OF MIXING IN THE SOLID-SOLUTION OF FE IN NI3AL

The vaporization of the alloy samples of the compositions (Ni3Al)(1-x) Fe-x (x = 0, 0.01, 0.02, 0.03, 0.04, 0.06, 0.08) was investigated at t emperatures between 1304 to 1698 K by the use of Knudsen effusion mass spectrometry in order to obtain thermodynamic data for the solid solu tion gamma'phase of the type Ni3Al. The partial pressures of Al, Fe, a nd Ni were determined over the samples investigated, Excess partial en thalpies, excess partial entropies, and excess chemical potentials at a temperature of 1473 K resulted for the components in the gamma' solu bility range. New results on the phase boundaries of the gamma' solubi lity range were obtained by the analysis of quenched alloy samples and from the mass spectrometric studies. The results obtained are discuss ed with respect to the solubility behavior of Fe in;the gamma' phase.