No abstract

The PbO–Al2O3 system has been extensively studied in literature. In the present study, experimental work was conducted in which equilibria between phases were investigated under air between 600°C and 800°C by X-ray diffraction. Three intermediate compounds reported in literature were confirmed, which are PbAl12O19 (1PbO:6Al2O3), PbAl2O4 (1:1) and Pb2Al2O5 (2:1). Results support a widely accepted version of the phase diagram in which these compounds exist. On the basis of the results obtained in this study and data considered from literature, a thermodynamic modeling according to the Calphad approach was performed, where all intermediate phases were considered as stoichiometric compounds and where the liquid phase was described by a two-sublattice ionic liquid model. Good agreement has been obtained from thermodynamic optimization in comparison with experimental results.

The present work is dedicated to the description of the pseudo-binary Al 2 O 3 -Bi 2 O 3 and the isothermal section at 600°C of the system Al 2 O 3 -Bi 2 O 3 -PbO according to a Calphad approach. It takes part of the complete description of the complex system Pb-Bi-Fe-(Al,Cr)-O. Such study is of high interest for the nuclear community that aims to develop protective coatings for the MEGAPIE spallation target to prevent the T91 steel from corrosion due to contact with lead-bismuth eutectic liquid.A survey in literature has revealed a discrepancy between equilibrium phases diagrams related to the Al 2 O 3 -Bi 2 O 3 system where four different compounds were reported. Therefore, an experimental reinvestigation of the system was necessary. Samples were prepared from mixtures of powders of high purity at different compositions then annealed at different temperatures. Different techniques were used to characterize the samples: XRD, SEM (EDS and WDS) and DTA. Only two stoichiometric compounds were found to be stable at low temperature, and invariant transformations were determined. The same process was used in case of addition of PbO. A modeling of the binary is also proposed.