Comparison of Corrosion and Cavitation Erosion Behaviors Between the As-Cast and Friction-Stir-Processed Nickel Aluminum Bronze

An as-cast nickel aluminum bronze (NAB) was treated by friction-stir processing (FSP). Immersion test and electrochemical measurements under cavitation erosion condition were carried out to investigate the long-term and short-term corrosion behaviors of the as-cast and as-FSP NAB. Cavitation erosion tests were conducted in both distilled water and 3.5 wt% sodium chloride (NaCl) solution. The immersion test indicated that the electrochemical impedance of the as-FSP NAB was much higher, while there was little difference between them in the short-term test. The cumulative mass loss of the as-cast NAB was about 1.5 and 2 times as large as that of the as-FSP in distilled water and 3.5 wt% NaCl, respectively. The higher corrosion resistance of the as-FSP was a result of the refined and homogenized microstructure. Improved mechanical properties and fewer galvanic corrosion sites are attributed to the higher cavitation erosion resistance of the as-FSP NAB.