Designing highly ductile magnesium alloys: current status and future challenges

In order to reduce oil consumption and avoid fossil fuel-related environmental problems, scientists are always looking for lightweight structural materials that show high performance during both processing and application. Among various candidates, Mg seems to be the most promising. Mg is ∼33, 60, and 75% lighter than Al, Ti, and steel, respectively. However, the vast applications of Mg are impeded due to its intrinsic brittleness at room temperature, which is related to the hexagonal close-packed crystal structure of Mg. In this crystal structure, the limited number of independent slip systems available at room temperature leads to brittle behavior and low fracture toughness. Thus, engineers and scientists all over the world have shown a great deal of interest in fabricating Mg-based materials with improved ductility. In this review, accordingly, the origin of low ductility in pure Mg and the fundamentals of designing highly ductile Mg alloys will be presented and critically discussed. In addition, the recent advances achieved in the field of Mg alloys with high ductility via control of structure and composition will be outlined. Finally, various properties of highly ductile Mg-based materials, including creep, fatigue, corrosion, and formability, will be discussed.