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

Abstract

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 α-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 6.0∼6.2 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, α-Mg phase was regarded as hydrogen storage system and the eutectic area acted as the catalytic system.