Hydrogenation properties of ball-milled MgH2–10wt%Mg17Al12 composite

As-cast Mg17Al12 alloy was prepared by induction melting method, and then ball-milled with MgH2 for 50 h to obtain MgH2–10wt% Mg17Al12 composite. The structure and morphology of the composite were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS). XRD results showed that MgH2 decomposed partly during ball milling. Ball-milled Mg17Al12 alloy could absorb hydrogen at the temperatures over 473 K and desorb hydrogen at 613 K. The MgH2–10wt% Mg17Al12 composite showed rapid H-absorption rate and higher H-capacity with good activation properties, compared with ball-milled MgH2. With the increase in hydriding temperature, the maximum hydrogen absorption capacity of MgH2–10wt% Mg17Al12 composite increased from 1.12 wt% at 393 K to 6.50 wt% at 473 K. The favorable hydrogenation performance of the MgH2–10wt% Mg17Al12 composite was mainly attributed to the synergistic effect of the catalytic efficiency of Mg17Al12 alloy and defects on the surface and/or in the interior of Mg formed during ball milling process.