Dealloying of a Nickel–Aluminum Bronze Impeller
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A brackish water pump impeller was replaced after 4 years of service, while its predecessor lasted over 40 years. The subsequent failure investigation determined that the nickel–aluminum bronze (NAB) impeller was not properly heat treated, which made the impeller susceptible to aluminum dealloying. The dealloying corrosion was exacerbated by erosion, because the pump was slightly oversized. This investigation recommended proper heat treatment of NAB alloys that are to be used in salt water or brackish service. Additionally, the investigation recommended closer evaluation of new pumps to ensure that they are properly sized.
KeywordsDealloying Nickel–aluminum bronze Impeller Corrosion Seawater
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