Reaction of Zircaloy-4 with tellurium under different oxygen potentials

Corrosion behavior of Zircaloy-4 has been studied under different oxygen potentials and tellurium vapor pressures. The oxygen potential was controlled by buffer over the range of −600 to −430 kJ/mol. Under the condition of oxygen potential of less than −500 kJ/mol with coexisting tellurium vapor, duplex corrosion layers were formed on the surface of Zircaloy-4 specimens, which consisted of zirconium telluride and zirconium oxide. The thickness of corrosion layer was increased with tellurium vapor pressure. For the oxygen potential over −430 kJ/mol, only zirconium oxide was observed on the specimen surface regardless of coexistence of tellurium vapor.