Magnesium (Mg) alloys typically exhibit anisotropic mechanical behaviors due to their hexagonal close-packed (hcp) crystal structures, often leading to tension-compression asymmetries. Understanding of the asymmetrical and related deformation mechanisms is crucial for their structural applications, particularly in the lightweight transportation industries. Nevertheless, the underlying deformation mechanisms (e.g., slip versus twinning) at each deformation stage during tension and compression have not been fully understood. In this study, we employed tensile and compressive tests on extruded Al and Mn containing Mg alloy, i.e., an AM alloy Mg-0.6Mn-0.5Al-0.5Zn-0.4Ca, during the synchrotron X-ray diffraction. Our results show that distinct deformation behaviors and mechanisms in tension and compression are associated with the strong texture in the extruded samples: (i) The tensile deformation is dominated by dislocation slips, with activation of non-basal 〈a〉 and 〈c + a〉 slip, but deformation twinning is suppressed. (ii) The compressive deformation shows early-stage tensile twinning, followed by dislocation slips. Twinning induces grain reorientation, leading to significant lattice strain evolution aligned with the texture. The pronounced tension-compression asymmetry is attributed to the favorable shear stress direction formed in the twinning system during compression, which facilitates the activation of tensile twins. During tension, the strain hardening rate (SHR) drops significantly after yielding due to limited activated slip systems. In contrast, the samples under compression exhibit significant increases in SHR after yielding. During compression, dislocation multiplication dominates the initial strain hardening, while twinning progressively contributes more significantly than dislocation slip at higher strains. This study improves our understanding of the tension-compression and strain hardening asymmetries in extruded AM Mg alloys.

It is one concern of the researchers how magnesium (Mg) alloys solidify under different conditions and how their microstructure evolves during solidification, and what are the relationship between the macroscopic properties and various microstructures. Such issues are difficult to be revealed through experiments only, especially for the newly developed Mg alloys, for which there is a lack of more systematic and mature system. However, multi-scale modeling and simulation can promote and deepen our understanding of the microstructure and its deformation mechanism. In this paper, we review and summarize the recent research progress of numerical simulation of Mg alloys in forming and microstructure, namely casting, extrusion, rolling, and welding, using crystal plasticity finite element (CPFEM) and molecular dynamics (DM) methods. Besides, the methods and innovations of modeling are also summarized. Lastly, the paper discusses the development prospects and challenges of the numerical simulation in the field of Mg alloys.