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As the lightest structural metal and one of the most abundant metallic elements on earth, magnesium (Mg) has been used as an “industrial metal” for lightweighting in the transportation and electronics industries, in addition to other traditional applications in aluminum alloying, steel desulfurization and protective anodes. In recent years, research has shown significant potential for Mg to become a “technology metal” in a variety of new applications from energy storage/battery to biomedical products. However, global Mg production has shown steady but moderate growth in the last three decades. Mg applications as an industry metal are still limited due to some sustainability concerns of primary Mg production, as well as a number of technical issues related to the structural and corrosion performance of commercial Mg alloys. New Mg applications as an industrial or technology metal face tremendous technical challenges, which have been reflected in the intensified global research efforts in the last twenty years. This paper will review some past and present applications, and discuss future opportunities and challenges for Mg research and applications for the global Mg community.

In order to develop high strength Mg-Gd-Y-Zn alloys, key experiments coupled with CALPHAD (CALculation of PHAse Diagrams) calculations were carried out in the current work to provide critical understanding of this important alloy system. Three Mg-10Gd-xY-yZn (x = 4 or 5, y = 3 or 5, wt.%) were mapped on Mg-Gd-Y-Zn phase diagrams for phase equilibria and microstructure investigation. Electron microscopy was performed for phase identification and phase fraction determination in as-cast and solution treated conditions. In all three alloys, the major phases were Mg-matrix and long period stacking order (LPSO) 14H phase. With ST at 400 and 500 °C, the phase fraction of LPSO 14H increased, particularly the fine lamellar morphology in the Mg matrix. The as-cast and 400 °C Mg10Gd5Y3Zn samples had Mg5(Gd,Y) present. At 500 °C, Mg5(Gd,Y) is not stable and transforms into LPSO 14H. The Mg10Gd5Y5Zn alloy included the W-Phase, which showed a reduction in phase fraction with solution treatment. These experimental results were used to validate and improve the thermodynamic database of the Mg-Gd-Y-Zn system. Thermodynamic calculations using the improved database can well describe the available experimental results and make accurate predictions to guide the development of promising high-strength Mg-Gd-Y-Zn alloys.

The stacking fault energy is connected to the response of crystals to deformation. Here the authors report a computational study in a model NiCo system to demonstrate the key importance of the dislocation/solute interaction for the accurate assessment of stacking fault energy in alloys beyond dilute limit.

Medium entropy alloy CoCrNi has better mechanical properties than high entropy alloys such as CrMnFeCoNi, but why that is remains unclear. Here, the authors show that a nanostructured phase at lattice defects in CoCrNi causes its extraordinary properties, while it is magnetically frustrated and suppressed in CrMnFeCoNi.