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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.

In this study, three binary Mg–Ni alloys were prepared by gravity casting (GC) and mechanical alloying combined with spark plasma sintering (SPS). All samples were subjected to electrochemical hydriding in 6 mol/l KOH at 80 °C for 480 min. The structures and phase compositions of the samples were studied by optical and scanning electron microscopy, energy dispersive spectrometry and X-ray diffraction. The concentration of absorbed hydrogen was determined using an optical emission spectrometer with glow discharge for the GC alloys and using a hydrogen analyzer for the SPS alloys. The process of hydrogen evolution was observed by mass spectrometry for SPS alloys. The highest total amount of hydrogen was absorbed by the MgNi26 alloy both for both the GC and SPS alloys. The only hydriding product was MgH 2 in the α- and γ-modification. Compared to commercial powder MgH 2, the decomposition temperature was reduced by more than 200 °C, which can be ascribed to the catalytic effect of Mg 2 Ni and namely to the nanostructured magnesium formed after SPS.