Tailoring the Anodizability and Corrosion Resistance of AlSi Alloys by Microstructural Tuning

Abstract This work investigates the effect of the microstructure of a recycled AlSi10 alloy on its anodizability and corrosion resistance. 14 different cast batches are obtained by modulating casting parameters targeting different microstructures in terms of secondary dendritic arm spacings (SDAS), sizes of the five largest intermetallic precipitates (Aint,5) and average area of a single eutectic Si particle (ASi). Specimens are then anodized and the resulting anodic layers are characterized in terms of thickness, morphology, noise resistance (Rn) and surface impedance by using scanning electrochemical microscopy (SECM). It is shown that as the SDAS and size of intermetallic particles increase, the homogeneity of the anodic layers decreases, which has a relevant impact on the corrosion resistance of anodized specimens.