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Structural and hydrogen storage properties of melt-spun Mg-Ni-Y alloys

: Kalinichenka, S.; Röntzsch, L.; Kieback, B.


International journal of hydrogen energy 34 (2009), No.18, pp.7749-7755
ISSN: 0360-3199
Journal Article
Fraunhofer IFAM, Institutsteil Pulvermetallurgie und Verbundwerkstoffe Dresden ()

Nanocrystalline magnesium-rich Mg-Ni-Y alloys were produced by melt-spinning. They were characterized regarding their microstructure, crystallization behaviour, and cyclic hydrogenation/dehydrogenation properties in view of their application as reversible hydrogen storage materials. Transmission electron microscopy reveals that these alloys consist in the as-spun state of mixtures of nanocrystalline Mg(Ni;Y) grains that are embedded in an amorphous matrix. Differential scanning calorimetry and X-ray diffraction analysis show that these alloys undergo several crystallization steps in the temperature range between 180 and 370 degrees C. It was found that only a few thermal activation cycles of the as-quenched ribbons are required in order to reach excellent hydrogenation/dehydrogenation properties of these alloys. In thermogravimetric analyses using a magnetic suspension balance it could be shown that these alloys can reach reversible gravimetric hydrogen storage densities of up to 5.3 wt.%-H with hydrogenation and dehydrogenation rates of up to 1 wt.%-H/min even at temperatures of 250 degrees C. The structure of the alloys remains nanocrystalline even after several hydrogenation/dehydrogenation cycles.