Technical Note: Corrosion and Cavitation Erosion Behaviors of the Thermo-Mechanically Affected Zone (TMAZ) in a Friction Stir Processed Ni-Al Bronze

The microstructure, corrosion, and cavitation erosion behaviors of the thermo-mechanically affected zone (TMAZ) in a friction stir processed Ni-Al bronze were investigated. The TMAZ mainly contained elongated α, refined κ_II, β′, and a small portion of eutectoid microstructure α + κ_III. In 3.5 wt% NaCl solution, both the corrosion and cavitation erosion resistance ranked in the order: the cast substrate < the TMAZ < the stirred zone (SZ). Compared with the cast substrate, the TMAZ suffered less severe corrosion as a result of the reduction of eutectoid microstructure, which was susceptible to corrosion, and it was less severely damaged under cavitation erosion because it possessed higher hardness and exhibited more plastic deformation behavior. The SZ was more corrosion and cavitation erosion resistant than the TMAZ because it had the most homogeneous microstructure.