Novel multicomponent magnesium alloys: High strength-elongation synergy and PEO-driven corrosion resistance

• Two magnesium-based multicomponent alloys Mg-0.1Ag-0.15Ca-0.2Ce-0.1Mn-0.1Sn-0.2Sr-0.5Zn (wt.%) (MA) and Mg₈₂(CaMnZn)₁₅Sn₂(AgCeSr)₁ (at.%) (HEA) were studied. • The MA alloy exhibited high strength (203 MPa) and elongation (21 %), making it suitable for load-bearing orthopedic applications. • PEO-treated MA alloy showed superior corrosion resistance with an i corr of 1.24 × 10⁻⁸ A/cm² in SBF. • When immersed in SBF, the PEO-coated MA alloy facilitated the formation of an apatite layer with a Ca/P ratio of 1.66, confirming its enhanced osteoconductivity for bone regeneration. This study investigates the innovative approach of utilizing multiple alloying elements at micro-alloying levels to enhance solution strengthening and their contrasting behaviour in higher compositions leading to intermetallic formation. Two magnesium-based alloys were developed: a high entropy alloy (HEA) Mg 82 (CaMnZn) 15 Sn 2 (AgCeSr) 1 (at.%) and a micro-alloy (MA) Mg-0.1Ag-0.15Ca-0.2Ce-0.1Mn-0.1Sn-0.2Sr-0.5Zn (wt.%). The micro-alloy demonstrated exceptional mechanical performance, achieving a tensile strength of 203 MPa and an impressive elongation to failure of 21 %, underscoring its potential for load-bearing applications. To enhance surface properties and corrosion resistance, plasma electrolytic oxidation (PEO) treatment was applied, resulting in significantly improved surface hardness and corrosion resistance. Notably, the PEO-treated micro-alloy achieved a corrosion current density (icorr) of 1.24 × 10⁻⁸ A/cm² in simulated body fluid (SBF), indicative of its superior degradation resistance. Bioactivity evaluations further revealed a stable pH profile and a near-stoichiometric Ca/P ratio of 1.66 on the PEO-coated micro-alloy surface, confirming its enhanced osteoconductivity and potential for biomedical applications. This work establishes a foundation for advancing magnesium-based alloys tailored for orthopaedic implants and other biomedical devices.