Thermodynamic activities in Zircaloy-4 by mass spectrometry

Thermodynamic activity of tin in Zircaloy-4 has been determined over a temperature range from 1062 to 2315 K. At the lower end of the temperatures, the activities were determined from equilibria between the Zircaloy-4 and tellurium vapor. At the high temperature end, activities were determined by direct vaporization. Chromium and iron activities were determined at two temperatures. Activity coefficients were computed for tin and also the iron and chromium. Activity coefficients for chromium and iron are of the order of unity (2 and 3, respectively), indicative of near ideal behavior in the Zircaloy-4. The activity coefficient of tin, however, is of the order of 10-2 which is indicative of strong attractive forces between the zirconium and tin in Zircalloy-4. (orig.)