CONSTITUTION AND THERMODYNAMICS OF FE-PR ALLOYS

The thermodynamic properties of Fe-Pr alloys have been determined betw een 923 and 1073 K by emf measurements on galvanic cells using CaF2 as a solid electrolyte. The activity of Pr in iron-rich solid solution a lloys shows positive deviations from ideality. The Gibbs energy of the intermetallic compound Fe17Pr2 was determined to be -1,28 [kJ/mol ato ms] at 1073 K. The phase relations of the Fe-Pr system have been exami ned by X-ray diffraction and DTA. Optimized descriptions of the phase diagram and the thermodynamic functions of the Fe-Pr system have been obtained from experimental thermodynamic and phase diagram data using a computer program based on the least squares method. Optimized and ex perimental data are in excellent agreement.