An investigation was carried out to study the effect of the microstructure of nickel-aluminum-bronze alloy (UNS C95520) on its cavitation corrosion behavior in seawater, using a 20-kHz ultrasonic induced cavitation facility. Cavitation tests were made under free corrosion conditions as a function of exposure time in natural seawater for this alloy. Optical and scanning electron microscopy showed that UNS C95520 immersed in stagnant seawater suffered from selective corrosion of the copper-rich α phase at boundaries with intermetallic κ precipitates. The κ precipitates and precipitate-free zones did not suffer corrosion. Cavitation made the surface of this alloy very rough, with large cavities or pits, ductile tearing, and corrosion of the boundaries of the α columnar grains. In addition, the number of cavities and their size have increased with exposure time. Selective phase corrosion and cavitation stresses were considered the causes of the cracks observed.

Subject
Scanning electron microscopy, Cavitation, Test methods, Materials, Metal surfaces, Microstructure, Precipitates, Microcracks, Roughness, Seawater, Corrosion attacks, Alloys, Grain
Keywords:
Cavitation, corrosion, intermetallic, microstructure, seawater
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2018
Association for Materials Protection and Performance (AMPP)
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