Mass-spectrometric determination of thermodynamic properties of liquid Co-Cr alloys

Thermodynamic excess functions of Co-Cr alloys in the liquid phase have bee n investigated by Knudsen-cell mass spectrometry in the concentration range 0.2'72-0.605 atomic fraction (at fr.) of Cr in the temperature range 1710- 1860 K. The molar excess Gibbs energies, entropies, and enthalpies as well as the thermodynamic activities of components in the Co-Cr system were obta ined using composition and temperature dependence of the ratio of intensiti es of Co-59 and Cr-52 ions, The results show that subregular solution model would fit the measured data well: (2-parameter thermodynamically adapted p ower (TAP) series: C-n(H) in J/mol: C-1(H) = -18400, C-2(H) = 13000, C-n(S) in J/(mol.K): C-1(S) = -2.5, C-2(S) = 0.2.).