Progress in creep-resistant RE-containing Mg-Al alloys: From micro-mechanisms and composition design to structure-property relationships

Mg-Al based alloys are the dominant commercial magnesium alloys but suffer from inferior creep resistance at elevated temperatures, which strictly limits their application in heat-resistant components. Alloying with rare earth (RE) elements is widely recognized as a critical strategy to enhance their high-temperature performance. This paper systematically reviews the high-temperature creep behavior and strengthening mechanisms of RE-containing Mg-Al alloys. The strengthening mechanism primarily relies on the formation of heat-resistant precipitates and solute segregation. These microstructural features effectively pin dislocations and suppress grain boundary sliding, thereby significantly reducing the creep rate. Following this, current composition design methodologies are highlighted, emphasizing the application of CALPHAD, first-principles calculations, and machine learning. Subsequently, the effects of various RE and alloying elements on microstructural evolution and properties are critically analyzed. Building on the understanding of these strengthening mechanisms, an ideal microstructural architecture tailored for superior creep resistance is proposed, which is distinctly characterized by a robust, thermally stable grain boundary skeleton to suppress grain boundary sliding, coupled with high-density intragranular nano-dispersoids to effectively pin dislocation motion. Furthermore, the influence of processing technologies—casting, heat treatment and thermomechanical processing—on creep performance is summarized. Finally, future development trends are outlined, specifically focusing on innovations in multi-scale integrated computational design, microstructural regulation, and synergistic processing technologies. Such strategies are expected to accelerate the development of next-generation heat-resistant magnesium alloys, satisfying the stringent requirements of aerospace and automotive applications.