Enhancing Mechanical and Corrosion Properties of Mg–Zn–Mn–Ca–RE Alloy Improved by Combining Extrusion Plus Rolling Process

This study investigates the microstructural evolution, mechanical properties, and corrosion behavior of ZM31, ZMX310, ZMX310‐LaCe, and ZMX310‐LaSm alloys processed by extrusion–rolling (ER). The ER process markedly enhances strength, particularly in ZM31 and ZMX310‐LaSm. The yield strength (YS) of ZM31 increases from 181 to 318 MPa, while that of ZMX310‐LaSm rises from 283 to 358 MPa, with only a slight reduction in elongation. The retained ductility is associated with texture weakening and the formation of a bimodal grain structure, although the latter is regarded as a microstructural feature rather than an independently verified strengthening mechanism. Rare‐earth additions also improve corrosion resistance. ZMX310‐LaCe exhibits the lowest hydrogen evolution rate (HER) of 0.007 mL·cm −2 ·h −1 , approximately 2% of that of ZM31. ZMX310‐LaSm shows a stable and adherent surface film, a single capacitive arc, a higher corrosion potential, and a lower corrosion current density. Overall, ER processing combined with La/Ce or La/Sm alloying synergistically improves the strength and corrosion resistance of Mg–Zn–Mn–Ca alloys.