Structural and hydrogenation properties of SrAl2−xNix alloys

In this paper, Al was partially substituted by Ni in the Zintl phase alloy SrAl2 and the structural and hydrogenation characteristics of the SrAl2−xNix (0 ≤ x ≤ 0.4) alloys were studied by X-ray diffraction (XRD), scanning electronic microscopy (SEM) and hydrogenation measurements. The alloy consisted of a single Zintl phase of SrAl2 when x = 0. However, partial substitution of Al by Ni resulted in multiphase structure of the alloys. When x = 0.1, the alloy was composed of SrAl2, Sr5Al9, SrAl and AlNi phases. With the increase of x, the amount of SrAl2 and Sr5Al9 phases decreased, while the amount of SrAl and AlNi phases increased. Hydrogenation measurements were made at 473 K under 3 MPa hydrogen pressure. It was interesting to find that the hydriding kinetics of the alloy was improved greatly after Ni substitution, which could be attributed to the catalysis of AlNi phase.