Abstract
Magnesium alloys have been widely studied for their corrosion behavior in electrolyte environments relevant to battery systems and are being explored for possible use as anode materials owing to their high theoretical capacity and low density. However, a major impediment to their extensive use is hindered by their susceptibility to corrosion, particularly in alkaline electrolytes. This study systematically investigated the effect of tin (Sn) addition on the electrochemical stability of AZ91 magnesium alloys. Specifically, AZ91 alloys were prepared with additions of 3 wt% and 5 wt% Sn (designated as AZ91–3Sn and AZ91–5Sn, respectively) by casting, and their corrosion performance was investigated in two distinct alkaline electrolyte media: 0.5 M KOH and a hybrid 0.5 M NaOH + 0.5 M KOH electrolyte. The phases and morphological features of the as-cast alloys were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). A comprehensive evaluation of the corrosion rate was performed using immersion testing and electrochemical methods, including Tafel polarization, linear sweep voltammetry (LSV), cyclic voltammetry (CV), and chronopotentiometry in a three-electrode system. The findings establish a clear composition-dependent corrosion response, demonstrating that Sn addition significantly affects the phase evolution, passive film integrity, and performance specific to the electrolyte. This study identified an optimal combination of Sn content and electrolyte environment that effectively mitigated anodic dissolution and improved overall electrochemical stability.