Microstructure and mechanical properties of low-rare-earth magnesium alloy sheets processed by hot working and aging

Magnesium alloys have gained increasing interest as lightweight structural materials owing to their high specific strength, excellent damping capacity, and electromagnetic shielding performance. Nevertheless, their relatively low strength, limited fatigue resistance, and inadequate high-temperature performance continue to restrict their wider application in aerospace and transportation. In this study, a low-rare-earth (LRE) magnesium alloy sheet was developed by alloying commercial AZ31B with a WE43 master alloy, followed by hot rolling and T5 aging treatment. The microstructure and phase composition were characterized using various microscopy and spectroscopic methods. The addition of rare earth (RE) elements resulted in the formation of Al 2 Y-containing precipitates, which may contribute to grain refinement and strengthening. However, their strengthening effect could not be quantitatively evaluated in the present study. Compared with AZ31B-H24, the LRE-Mg-T5 alloy exhibited improved yield strength (YS, 278 MPa) and ultimate tensile strength (UTS, 315 MPa), while maintaining acceptable ductility (8%). High-cycle fatigue (HCF) testing indicated a fatigue limit of approximately 124 MPa, and creep tests conducted at 473 K under 50 MPa revealed an extended secondary creep stage exceeding 250 h. These results suggest that the combined effects of LRE alloying and T5 aging can enhance the mechanical performance and high-temperature stability of AZ-based magnesium alloys, providing a cost-effective alternative to conventional high-RE alloys such as WE43.