Correlation between microstructure and corrosion and cavitation erosion behaviors of nickel aluminum bronze

Abstract

The microstructure, corrosion and cavitation erosion (CE) behaviors of the as-cast and four different heat treated nickel aluminum bronzes (NABs) in 3.5 wt.% NaCl solution were investigated. The results show that after annealing, β′ transformed into the eutectoid microstructure, and more κIV precipitated from α. Less eutectoid microstructure and more β′ were obtained after normalizing. The quenched NAB mainly consisted of α and β′ phases, and fine, acicular α and κ phases precipitated inside β′ after subsequent aging. The largest proportion of the eutectoid microstructure, which underwent severe selective phase corrosion, was responsible for the lowest corrosion resistance of the annealed NAB. The quenched NAB possessed the most protective film and hence the highest corrosion resistance. The mechanical attack was primarily responsible for the CE damage for the as-cast, annealed and normarlized NABs. The quenched and quenched + aged NABs exhibited superior CE resistance because of the high hardness. The CE−corrosion synergy dominantly caused CE degradation, and it was largely attributed to corrosion-enhanced-CE.