Hydrogen storage behavior of Mg/Ni layered nanostructured composite materials produced by accumulative fold-forging

An advanced and newly developed severe plastic deformation (SPD) method called accumulative fold-forging (AFF) was applied to produce layered nanostructured MgNi alloys exhibiting superior hydrogen storage capacity. Microstructural developments and storage properties were characterized in depth to correlate the structure and performance of this advanced material. The enhanced hydrogen storage performance of the magnesium-based layered composite material was investigated in comparison to the pristine state by conducting hydrogenation and dehydrogenation testing. It was also shown that the hydrogen uptake and release characteristics can be controlled by adjusting the layered structure or the Mg: Ni stoichiometry ratio. Refining the grain structure of the magnesium alloy down to the nano-scale range (∼400–900 nm) by applying high cycles AFF consolidation to promote creation of multi-million nanometric interfaces led to superior storage performance with a remarkable hydrogen absorption capacity of up to ∼1.425 wt%. X-ray diffraction (XRD) analysis of the hydrogenated products revealed the formation of MgH2 that indicates the dominance of the magnesium matrix for controlling the hydrogen storage behavior of the layered Mg/Ni composite material. Finally, the relationship between the directional hydrogen storage behavior and the induced structural features upon AFF treatment were also established using quantitative characterization and analytical tools.