The effect of transition metals on hydrogen migration and catalysis in cast Mg-Ni alloys

CHO, Y.H., AMINORROAYA YAMINI, Sima, LIU, H.K. and DAHLE, A.K. (2011). The effect of transition metals on hydrogen migration and catalysis in cast Mg-Ni alloys. International Journal of Hydrogen Energy, 36 (8), 4984-4992.

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Official URL: http://www.sciencedirect.com/science/article/pii/S...
Link to published version:: 10.1016/j.ijhydene.2010.12.090

Abstract

The inexpensive fabrication technique of casting is applied to develop new Mg–Ni based hydrogen storage alloys with improved hydrogen sorption properties. A nanostructured eutectic Mg–Mg2Ni is formed upon solidification which introduces a large area of interfaces along which hydrogen diffusion can occur with high diffusivity. After a few cycles of hydrogenation and dehydrogenation, an ultrafine porous structure formed in the eutectic Mg–Mg2Ni and some cracks developed along the interface between the eutectic and the α-Mg matrix. This indicates that hydrogen atoms introduced into the alloys preferentially migrate along the interfaces in the nanostructured eutectic which enables effective short-range diffusion of hydrogen. Furthermore, transition metals (TMs) such as Nb, Ti and V in the range 240–560 ppm are added directly to molten Mg-10 wt% Ni alloys and are found to form intermetallic compounds with Ni during solidification. The alloys can store 5.6–6.3 wt% hydrogen at 350 °C and 2 MPa. TM-rich intermetallics distributed homogeneously in the cast alloys appear to play a key role in accelerating the nucleation of Mg from MgH2 upon dehydrogenation. This leads to a significant improvement in the hydrogen desorption kinetics.

Item Type: Article
Uncontrolled Keywords: Hydrogen storage; Eutectic Mg–Mg2Ni; Porous structure; Transition metal rich intermetallics; Kinetics
Research Institute, Centre or Group: Materials and Engineering Research Institute > Engineering Research
Identification Number: 10.1016/j.ijhydene.2010.12.090
Depositing User: Sima Aminorroaya Yamini
Date Deposited: 25 Jul 2017 16:01
Last Modified: 25 Jul 2017 16:01
URI: http://shura.shu.ac.uk/id/eprint/15962

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