Microstructures and mechanical properties of porous coating prepared by micro-arc oxidation on low-elastic-modulus Ti-19Zr-10Nb-1Fe alloy

β-Titanium alloys are well-known for their excellent mechanical properties, making them promising candidates for orthopedic implants. This study investigates the formation of hierarchical porous coatings on a β-Ti alloy, Ti-19Zr-10Nb-1Fe (TZNF), via micro-arc oxidation (MAO) to enhance surface properties. Coatings fabricated under varying voltage conditions were systematically analyzed for their microstructure, chemical composition, and mechanical properties. The results demonstrate that the coating exhibits a hierarchical nano/micro porous structure, with nanopores of 100–800 nm and micropores of 1–9 μm. Increasing the voltage enlarges the average pore size from 2.33 to 5.55 μm, while the surface roughness increases by 40–110 times compared to bare TZNF alloy. XRD analysis confirms the coating is primarily composed of mixed rutile/anatase TiO₂phases, while XPS reveals the presence of trace amounts of B₂O₃. Coating thickness increased with MAO duration, though the growth rate slowed beyond 180 s. The coatings exhibited excellent adhesion strength, with M − 300V achieving the highest bond strength of 37.47 ± 4.67 N. Surface microhardness was enhanced (up to 22.8 % improvement versus substrate). The MAO treatment preserves the substrate's mechanical integrity—a critical factor for enhancing long-term stability in biomedical applications. These findings establish fundamental guidelines for optimizing β-titanium alloy MAO processes, creating new opportunities for biomedical implants and other engineering applications.