Passive behavior of nickel-based superalloys prepared by high-deposition-rate laser solid forming additive manufacturing

We report the crystallographic texture and passive behavior of nickel-based superalloys prepared by high-deposition-rate laser solid forming (HDR-LSF) additive manufacturing in deaerated 10 wt.% NaNO₃. The HDR-LSF Alloy 718, mainly composed of columnar grains, is detected to be weakly fiber textured due to the direction changed structure. However, passive current densities on horizontal and vertical sections have no difference and both increase linearly with the electrode potential. Furthermore, the identical steady-state passive current density on both sections is attributed to the same film/solution interface energy. Amorphous structure of the bi-layer film induces the electrochemical activity isotropy regardless of matrix texture.