Microstructure of Hydrogenated Magnesium–Nickel Eutectic Alloy Based Composites and its Changes during Hydrogen Absorption/Desorption Cycling

In this work, we studied phase composition, hydrogen desorption kinetics and microstructural topology of hydrogen-sorbing composite materials prepared by ball milling under hydrogen of the powders of Mg 89 Ni 11 eutectic alloy without and with additive of graphene-like material (GLM). It was shown that in both cases the reproducible fast desorption kinetics were achieved after the fifth dehydrogenation—re-hydrogenation cycle. Using transmission electron microscopy, selected area electron diffraction, and the effect of MgH 2 radiolysis it was found that after seven hydrogenation–dehydrogenation cycles the material retains a highly dispersed microstructure: in the regions with a cross-sectional area of 1 micron in the size there are grains of Mg and Mg 2 Ni hydride-forming phases that are in direct contact, that favors the hydrogen sorption performance of the material.