Unveiling the Effect of Eutectic Silicon Morphology and Distribution on the Anodizability of a Recycled Cast AlSi10Mg Alloy

The work investigates the effect of eutectic silicon morphology and distribution on the anodizability and corrosion resistance of a recycled cast EN AC‐43 200 (AlSi10 Mg) alloy. A family of specimens combining different eutectic Si morphologies (platelet‐like and spheroidal) with variable secondary dendrite arm spacings (17 µm ≤ SDAS ≤ 38 µm) is produced by tuning the EN AC‐43 200 casting conditions. The samples are then anodized and characterized with several imaging and electrochemical techniques (i.e., optical and electron microscopy, electrochemical noise measurements, and scanning electrochemical microscopy), demonstrating an intriguing correlation between microstructure and corrosion resistance. In particular, it is shown that the corrosion protection capability of anodic layers is higher in those samples possessing reduced SDAS (<26 µm) and small, well‐spheroidized Si particles. The shape and distribution of Si particles are found to play a key role in achieving an anodic layer with good thickness homogeneity and an excellent degree of Si‐particle embedding, leading to high corrosion resistance.