Enhanced Corrosion Resistance of Plasma Electrolytic Oxidation Coatings on Ti–Mg Binary Materials

In response to the demand for lightweight materials in aerospace, automotive, and biomedical applications, Ti–Mg binary alloys offer a promising balance between the corrosion resistance of titanium and the low density of magnesium. Due to the limited solubility of Ti and Mg, bulk alloys are produced using powder metallurgy techniques, including high-energy ball milling, cold compaction, and hot isostatic pressing. Plasma electrolytic oxidation (PEO) is applied to improve corrosion performance. All compositions develop homogeneous ceramic bilayer coatings, with a porous outer layer and a compact barrier layer up to four orders of magnitude more resistive, effectively limiting ion diffusion at the substrate interface. Corrosion resistance, assessed via electrochemical impedance spectroscopy and hydrogen evolution, confirms significantly lower degradation rates for coated samples compared to bare alloys. Ti33 exhibits the highest corrosion resistance in both layers. Surface morphology varies with composition, showing pancake-, volcano-, and nodule-like porosities that influence protective behavior. These findings demonstrate that combining nonconventional processing with PEO treatment enables the fabrication of corrosion-resistant Ti–Mg materials, expanding their potential for biomedical implants and lightweight structural components.