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.

Plate impact experiments are conducted on aging-treated (AG) and solution-treated (ST) QE22 Mg alloy (Mg-2.5Ag-2.0Nd-0.7Zr) to investigate the effects of precipitates with different sizes on deformation and spall damage properties/mechanisms. The AG alloy contains the micron-scale intermetallic precipitates (δ) at grain boundaries and nano-scale precipitates (γ) in the matrix, while the ST alloy contains only the δ precipitates. Given the γ precipitate strengthening, the dynamic yield stress for the AG alloy (0.173 GPa) is about 40 % higher than that for the ST alloy (0.122 GPa). Upon shock loading, {1012}, {1011} and {1121} deformation twins are observed, and the γ precipitates significantly impede the growth of twins. The spall damage features of both samples are characterized and summarized via two dimensional scanning electron microscopy and three dimensional X-ray computed tomography. The voids/cracks are basically restricted within the δ phase at grain boundaries. In the AG alloy, the additional back-stress from matrix strengthened via γ precipitates suppresses void growth, leading to the less severe spall damage and 20 % higher spall strength (0.58–0.63 GPa) compared to the ST alloy (0.48–0.51 GPa). The present study provides insights into the roles of δ/γ precipitates in dynamic deformation and spallation of QE22 Mg alloy. Nano-scale γ precipitates improve both dynamic yield stress and spall strength, while micron-scale δ precipitates are conducive to the nucleation of spallation voids.

The orientation of precipitates was regulated by an improved twinning-aging-detwinning (TAD) process in Mg-Sn sheets. A structure with specific proportions of dual-precipitates was regulated, significantly enhancing the material’s strength. The formation mechanism of the dual-precipitates was investigated, and the evolution of precipitate orientation was confirmed. A combined SEM, EBSD and TEM method was developed to identify the coupling relationship between complex grain orientation and precipitate orientation. The orientation relationship between precipitates and the matrix could be quantitatively analyzed in the same region. Subsequently, the Orowan model was refined to quantify the strength enhancement effect following the orientation regulation of precipitates. The TAD sample containing dual-precipitates exhibited a 99.1% increase in TYS, equivalent to an increase of 108 MPa, compared to unregulated samples A. According to Orowan calculations, the theoretical strength increment from the three strengthening mechanisms was 113 MPa, closely matching the experimental increment of 108 MPa. Notably, the materials with a specific proportion of the dual-precipitates showed a substantial increase in strength.

The grain-scale tension-compression (T-C) asymmetric slip behavior and geometrically necessary dislocation (GND) density in an aged and twin-free Mg-10Y sheet were statistically studied using slip trace analysis and electron backscatter diffraction (EBSD) analysis. A significantly asymmetric slip activity, i.e., higher tensile slip activity and proportion of non-basal slip, was manifested. Prismatic 〈a〉 (37.1%) and basal 〈a〉 (27.6%) slips dominated the tensile deformation, followed by pyramidal Ⅱ 〈c + a〉 slip (20.0%). While during compression, basal 〈a〉 slip (61.9%) was the most active slip mode, and only 6.9% pyramidal Ⅱ 〈c + a〉 slip was observed. The critical resolved shear stress (CRSS) ratio was estimated based on ~800 sets of the identified slip traces, which suggested that the CRSS_{pyr Ⅱ}/CRSS_bas for compression was ~3 times than that of tension. The pyramidal Ⅱ 〈c + a〉 slip was more active when the slip plane was under tension than under compression, which was consistent with the calculated asymmetric CRSS_{pyr Ⅱ}/CRSS_bas. The activity of multiple slip, cross slip and slip transfer, as well as the GND density were also T-C asymmetric. This work thoughtfully demonstrated the T-C asymmetric slip behavior and plastic heterogeneity in Mg alloys which was believed to be responsible for the macroscopic T-C asymmetry when twinning was absent. The present statistical results are valuable for validating and/or facilitating crystal plasticity simulations.