Fabrication and evaluation of hydriding/dehydriding behaviors of Mg-10 wt.%Ni alloys by rotation-cylinder method

Even if the Mg-Ni alloys have been studied as one of the good lightweight hydrogen storage materials, the alloys have strong difficulties on fabrication process of mass products, until now. The Rotation-Cylinder Method (RCM) was initiated and has been developed to magnesium based composites with moderate rotation under normal atmosphere. In this study, the Mg-(1, 5, 10) wt.%Ni alloys were easily manufactured by RCM and evaluated to hydrogenation properties by Sieverts-type automatic pressure-composition-isotherm (PCI) apparatus at 523, 573 and 623 K. The evolution of microstructure of as-cast specimens appeared to be typical hypoeutectic structure. From the results of backscattered electron imaging (BEI) and energy dispersive X-ray spectrometry (EDS), the difference of composition between alpha-Mg and Ni-rich eutectic region was distinguished clearly. The hydrogenation properties of Mg-Ni alloys depended on the behavior of nickel compositions. The hydrogen capacity of Mg-10 wt.%Ni was 6.0similar to6.2 wt.%, and the plateau pressures were around 0.026, 0.18 and 0.67 MPa at 523, 573 and 623 K, respectively. Finally, in the Mg-Ni alloys produced by the RCM process, alpha-Mg phase was regarded as hydrogen storage system and the eutectic area acted as the catalytic system. (C) 2002 Elsevier Science B V. All rights reserved.