Handbook on Lead-bismuth Eutectic Alloy and Lead Properties, Materials Compatibility, Thermal-hydraulics and Technologies

3.2 Enthalpies, entropies (solid and liquid state) – free energy and entropy of mixing The heats of formation of six solid Pb-Bi alloys have been measured at 400 K in a liquid lead solution calorimeter by P. Roy, et al. They found that these alloys obey Kopp’s law of additivity and the heats of formation are therefore temperature independent. The lead and bismuth used in these experiments were reported to be of 99.999% pure. With their results, they calculated integral free energies and entropies of formation for solid Pb-Bi alloys at 400 K as a function of the Pb content.