Studies of the nobility of phases using scanning Kelvin probe microscopy and its relationship to corrosion behaviour of Ni-Al bronze in chloride media

An as-cast Ni-Al bronze (NAB) was subjected to friction-stir processing. The microstructure, nobility of the phases and corrosion behaviour of the as-cast and friction-stir processed NAB were studied using EPMA, scanning Kelvin probe force microscopy (SKPFM) and SEM, respectively. SKPFM results revealed that the lc phase in the as-cast NAB and the small-sized phases inside beta' in the friction-stir processed NAB exhibited relatively lower nobility. These phases were preferentially corroded in acidic chloride solution but protected in neutral chloride solution. The correlation between the nobility of the phases and the practical corrosion behaviour was also discussed. (C) 2014 Elsevier Ltd. All rights reserved.