Hydrogen-storage properties of gravity cast and melt spun Mg–Ni–Nb2O5 alloys

95%(gravity cast Mg–23.5Ni)–-5%Nb2O5 alloy was prepared by horizontal ball milling in n-hexane of gravity cast Mg–23.5wt%Ni with Spex milled Nb2O5. Melt spun Mg–23.5wt%Ni after heat treatment at 523 K for 1 h was also ground by planetary ball milling with finer Nb2O5 prepared by milling with NaCl. The activated 90%(melt spun Mg–23.5Ni)–10%Nb2O5 alloy shows higher hydriding and dehydriding rates than the activated 95%(gravity cast Mg–23.5Ni)–5%Nb2O5 alloy, thanks to the homogeneous distribution of fine Mg2Ni phase in melt spun Mg–23.5Ni and the finer Nb2O5 addition to melt spun Mg–23.5Ni, which leads to the effective diminution of the Mg particle size. The activated 90%(ms Mg–23.5Ni)–10%Nb2O5 alloy absorbs 4.70 wt%H at 573 K under 12 bar H2 for 10 min, and desorbs 4.75 wt%H at 573 K under 1.0 bar H2 for 25 min.