Corrosion behavior of TiZrHfNb high entropy alloy in nitric acid containing halide ions

High-Entropy Alloys (HEAs) are usually composed of five or more elements with equimolar or near equimolar elemental fractions when compared to conventional alloys containing one or two principal elements, and they form single solid solution phase. HEAs exhibit excellent microstructural stability at high temperature with better mechanical properties. In this work, the TiZrHfNbTa alloy was developed and characterized for its corrosion properties in severe environments such as boiling nitric acid, chlorinated nitric acid and fluorinated nitric acid. These severe environments are encountered in the aqueous reprocessing of spent fuels of fast breeder nuclear reactors. The passivation and corrosion mechanism of this TiZrHfNbTa alloy have been discussed based on the Gibbs energies of formation of respective metal oxides, metal chlorides and metal fluorides of the constituent element of the alloy. Further, SEM and XPS investigations were carried out to understand the corrosion behavior of this alloy. (author)