Hydrogen storage kinetics of as-cast and spun (Mg24Ni10Cu2)100-xNdx (x = 0-20) alloys

(Mg24Ni10Cu2)100-xNdx (x = 0, 5, 10, 15, and 20) alloys with nanocrystalline and amorphous structures were prepared by melt-spinning. X-ray diffraction and high-resolution transmission electron microscopy reveal that the as-spun Nd-free alloy displays an entirely nanocrystalline structure, whereas the as-spun Nd15 alloy, differing from Nd0 alloy, exhibits nanocrystals embedded in an amorphous matrix. This suggests that the addition of Nd facilitates the amorphous formation ability of the alloys. Melt spinning significantly improves the gaseous and electrochemical hydrogen storage kinetics of the alloys. Furthermore, melt spinning enhances the diffusion ability of hydrogen atoms in the alloy, but it impairs the charge-transfer reaction on the surface of the alloy electrode, which gives rise to the high-rate dischargeability of the alloy electrode, first mounting up and then going down with the increase in spinning rate.