Structural and hydrogenation properties of SrAl_2-xNi_x alloys

In this paper, Al was partially substituted by Ni in the Zintl phase alloy SrAl₂ and the structural and hydrogenation characteristics of the SrAl_2-xNi_x (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 SrAl ₂, 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.