Thermodynamic assessment of the LiF-NiF2, NaF-NiF2 and KF-NiF2 systems

摘要

Using the modified quasi-chemical model in the quadruplet approximation, three new thermodynamic assessments of binary systems useful for the detailed operational design of the Molten Salt Reactor are presented: AF-NiF2 (A = Li, Na, K). These systems are particularly relevant for the study of the molten salt-structural materials interaction, as the salt containment is made of a Ni-based alloy. Using powder X-ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC), new experimental data were gathered for two of these systems, LiF-NiF2 and KF-NiF2, and compared to previous experimental assessments. Our data have confirmed the formation of a (Li1-2xNix)F solid solution. The three thermodynamic models show a very good agreement with the experimental data. The melting point of NiF2 was measured for the first time to be T = (1629 +/- 5) K, and the thermal expansion coefficient for Li2NiF4 was found to be alpha = 27.6.10(-6) K-1 in the temperature range T = (298-773) K. (C) 2018 The Authors. Published by Elsevier Ltd.