Effects of microstructure on the hydrogen storage properties of the melt-spun Mg-5Ni-3La (at.%) alloys

Nanocrystalline and amorphous microstructures prepared by rapid solidification (RS) processing are effective in improving the absorption/desorption kinetics of the Mg-based hydrogen storage alloys. In this paper, the as-cast, nanocrystalline and amorphous Mg-5Ni-3La (at.%) alloys were prepared, and effects of microstructure on the hydrogen storage properties of the alloys were studied. The nanocrystalline and amorphous Mg-5Ni-3La (at.%) alloys show better absorption/desorption kinetics than that of the as-cast alloy due to the smaller grain size and more grain boundaries. The values of ΔH (enthalpy) for the Mg-H2 system of the nanocrystalline and amorphous alloys are −74.0 ± 1.2 kJ mol−1 and -66.1 ± 3.4 kJ mol−1, respectively, which are significantly lower compared to that of the as-cast alloy (−77.7 ± 0.3 kJ mol−1). •The nanocrystalline and amorphous Mg-5Ni-3La alloys are obtained by rapid solidification process.•The nanocrystalline alloy has the highest hydrogen storage capacity (5.9–6.0 wt%).•Smaller grain size and more grain boundaries are responsible for faster hydriding kinetics.