Why does seawater corrosion significantly inhibit the cavitation erosion damage of nickel-aluminum bronze?

The cavitation erosion (CE) and corrosion behaviors of cast and forged Nickel-aluminum bronzes were studied in deionized water and artificial seawater. Surprisingly, their CE mass losses in seawater were obviously less. Similar to forging process, cavitation load could cause α phase to transform into β phase and dislocation to form in subsurface, which were beneficial to improve mechanical properties. β and κ phases were more easily to be dissolved in corrosion tests. However, cavitation heat changed corrosion mechanism and induced formation of a dense oxide film on surface, which could protect materials covered under it and reduce CE damage. • Seawater corrosion had inhibitory effect on CE damage of NABs • The α phase in NAB-Casting underwent martensitic transformation in CE process • A dense oxide film was formed on the surface of NABs after CE in seawater • Cavitation heat changed the corrosion mechanism of NABs in seawater • The CE mass loss of NAB-Forged in seawater decreased by 7 times