Cooperative dehydriding mechanism in a mechanically milled Mg–50 mass% ZrMn2 composite

Structural and hydriding/dehydriding properties of the Mg–50 mass% ZrMn2 composite synthesized by reactive mechanical milling (RMM) method in hydrogen atmosphere are investigated by XRD, SEM/EDS and TG/DTA measurements. The effects of rotational speed and the milling time on the hydriding/dehydriding properties are examined in order to find out the most efficient milling condition for hydrogen storage of the composite. The composite prepared by RMM at 400 rpm for 1 h absorbs hydrogen rapidly at room temperature, where the composite hydride composed of MgH2, Mg and ZrMn2Hx is formed, and desorbs 2.6 mass% hydrogen at around 275 °C without decomposition. Cooperative dehydriding mechanism originated in the elastic interaction between MgH2 and ZrMn2Hx through their interface boundary is proposed for the composite.