Columnar structure and electrochemical anisotropy of a nickel-based superalloy fabricated via laser solid forming

Abstract: Electrochemical anisotropy has drawn substantial attention in the fields of electrochemical dissolution and corrosion, and it is related to the surface energy levels in a single-phase alloy. Here, laser solid forming (LSF) Inconel 718 alloy was found to be a multi-phase alloy with a strong fiber texture. Its horizontal section (HS), in which secondary phases have a tube-like distribution, mainly consists of the (001) crystallographic plane, while a vertical section (VS) with a strip-like secondary phase, consists of the (001) crystal zone. The HS was first measured to be more electrochemically stable but it has a higher anodic dissolution rate than VS in 10 wt% NaNO₃. Contrast analysis indicates that the electrochemical anisotropy can primarily be attributed to the columnar structure. Therefore, researchers should be very careful when using a surface energy model to predict the electrochemical anisotropy of a highly textured alloy. Graphical Abstract: For convenience, the red-colored secondary phases are continuous. Actually, they are continuous or discontinuous. (Color figure online)[Figure not available: see fulltext.].