Heat capacity and phase transition of Zircaloy-4

Heat capacity from 300 K to 1100 K and enthalpy change of the phase transition of Zircaloy-4 between 1080 K and 1270 K were measured with a triple-cell-type differential scanning calorimeter and a twin-type drop calorimeter. Heat capacities measured with these two apparatuses were in good agreement with each other, and they were several % less than the other literature values. They were also in good agreement with the values calculated by assuming the additivity of the contributions of the elements and the values of pure zirconium. On the phase transition, two peaks were observed in the temperature range from 1080 K to 1270 K. The first peak was assigned to a eutectic temperature of the Zr-Fe system or the Zr-Cr system, and the second peak was considered to come from the alpha-beta phase transition of Zr affected by Sn and O. The enthalpy change of the alpha-beta phase transition (Delta H-tr) was determined to he 4.12 +/- 0.35 kJ mol(-1) which was in good agreement with literature values for pure Zr. (C) 1997 Elsevier Science B.V.