The local corrosion behavior of additive manufactured AlSiMg specimens was studied using the SEM and SKPFM techniques. A morphological characterization of corroded areas revealed that crystallographic pitting developed in the aluminium grains inside the melt pool borders, from where corrosion spread to adjacent zones. The local Volta potential analysis showed that there is a close relation between the cellular grain size and the potential difference between the silicon and the aluminium phase. SKPFM measurements explained why the melt pool borders were more severely attacked by corrosion than other regions in the surface of the AM specimens. In regions with larger and coarser microstructures, greater potential difference between the phases was found, which represents a higher driving force for galvanic corrosion.

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The galvanostatic anodizing behavior of additive manufactured (AM) Al-Si10-Mg alloy was studied in H2SO4 electrolyte. The analysis of the voltage vs time response was complemented with a systematic characterization of the anodic oxide layer using a variety of techniques. In addition, a cast alloy of approximately the same chemical composition as that of the AM specimens was used as a reference in this study. Significant differences were found in the voltage-time characteristics of the samples analyzed. Besides, an anisotropic anodizing behavior was observed in the additive manufactured specimens. Due to the fine silicon microstructure present in the additive manufactured samples, the anodic oxide growth was much more obstructed than for the cast alloy. Nevertheless, even though the oxide layer was generally thinner in the AM samples for the same conditions and anodizing time, a much more continuous and uniform oxide layer was found in the additive manufactured specimens compared to the cast alloy. The porous structure was found to be greatly affected by the fine distribution of the silicon phase in the AM parts.

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