Effect of further precipitate refinement on mechanical properties and corrosion behavior of additively manufactured nickel aluminum bronze

The underwater direct metal deposition (UDMD) technique was employed to investigate the effects of further precipitate refinement on the mechanical and corrosion properties of additively manufactured nickel aluminum bronze (NAB) alloys, with conventional onshore direct metal deposition (DMD) used for comparison. The results demonstrated that both additively manufactured NAB samples exhibited suppressed precipitation of κ_Ⅰ and κ_Ⅳ phases. However, the κ_Ⅲ precipitates in UDMD-processed samples were finer and more uniformly distributed in the interdendritic regions, thereby enhancing the tensile strength compared with DMD-processed samples. NAB alloys prepared by the UDMD process exhibited better corrosion resistance, with the corrosion current reduced by nearly half compared with the DMD process. This enhanced corrosion resistance is attributed to the formation of a denser and more uniform corrosion product film after 30 days of immersion. Moreover, the enhancement in cavitation erosion resistance was limited due to an increase in phase boundaries after precipitate refinement. These findings provide insights into the mechanical and corrosion performance of NAB alloys following continuous refinement in additive manufacturing.