Binary and ternary phase diagrams of lead, bismuth, and lead oxide

The phase diagrams of binary and ternary mixtures of lead (Pb), bismuth (Bi), and lead oxide (PbO) are necessary for the application of Pb-Bi alloys as coolants in nuclear reactors. In this study, the solidus and liquidus temperatures of Pb-Bi, Pb-PbO, Bi-PbO binary mixtures and the liquidus temperature of Pb-Bi-PbO ternary mixture were measured via differential thermal analysis. The eutectic points of the three binary mixtures and the liquidus temperature of ternary mixture were experimentally determined and the effect of PbO on the phase diagram of the Pb-Bi mixture was analyzed. Furthermore, an optimized regular solution model, which showed much better prediction accuracy than the traditional model, was proposed for the phase diagrams of sub-binary and ternary Pb-Bi-PbO mixtures.