Structural and hydriding studies of Ca(Al1−xNix)2 alloys

The phase relations and hydriding characteristics of the Ca(Al1−xNix)2 (x = 0, 0.1, 0.2, 0.3 and 0.4) alloys were studied. It was found that partially substituting Al by Ni in CaAl2 alloy leads to the co-existence of multiple phases. When x = 0.1, 0.2 and 0.3, the alloys consist of C15, Ca13Al14 and NiAl phases. The amount of the C15 phase decreases with the increase of x. Further increasing x to 0.4, the C15 phase disappears entirely and the alloy contains Ca8Al3, NiAl and Ca. The partial substitution of Al by Ni cannot effectively improve the hydrogen storage properties of CaAl2 because the lattice parameter of the C15 phase decreases slightly after the substitution.