Mechanisms for Synergistically Enhanced Mechanical Properties and Corrosion Resistance in Mg−Al−Sn Alloys

• • Grain refinement from ~50 μm to below 5 μm via RE alloying and rolling delivers a yield strength of 238 MPa and elongation of 23% in ATXM-0.1Y, enabling structural components with improved damage tolerance and weight savings in automotive and aerospace applications. • • Corrosion rate reduction to ~1.7 mm/a for ATXM-0.1Y—an ~80% decrease versus TRC ATXM—directly extends service life in humid environments, lowering maintenance costs and expanding applicability in electronics and transportation. • • Transformation of Al8Mn5 to Al8Mn4RE phases reduces individual galvanic corrosion and strengthens the corrosion product film, providing a dual mitigation strategy that addresses both electrochemical and barrier degradation mechanisms. • • Comparative screening of Sm, Ce, and Y reveals Y as the optimal addition: 238 MPa yield strength, 305 MPa tensile strength, 23% elongation, and 1.7 mm/a corrosion rate, establishing a clear alloying selection criterion for industrial scale-up.