Deformation Response of Mg-Y Alloys under Dynamic Loading

Weight reduction of automobiles and aircrafts improves fuel economy and reduces greenhouse gas emissions. Use of Mg alloys may allow weight reduction because of their low densities, but adoption is hindered because they exhibit limited ductility at ambient temperatures [1]. In a previous study of fracture toughness in a Mg alloy, crack readily propagated near twin boundaries and resulted in poor durability [2]. It has been shown that pile-up of dislocations at the interface between the matrix and deformation twins caused stress concentration to form cracks [2]. Another study suggested that the ductility of Mg alloys is further limited under dynamic loading due to lowered activity of dislocations [3]. It has also been reported that a Mg-Al-Mn alloy had pronounced mechanical anisotropy at high strain rates of around 1.0 ×103 s-1 [4]. Therefore, the mechanical properties of Mg alloys should be evaluated accurately for applications involving possible dynamic loading.