Electrochemical hydriding of Mg-Ni alloys compacted by spark plasma sintering

In this study, three binary Mg-Ni alloys were prepared by gravity casting (GC) and mechanical alloying combined with spark plasma sintering (SPS). All samples were subjected to electrochemical hydriding in 6 mol/l KOH at 80 °C for 480 min. The structures and phase compositions of the samples were studied by optical and scanning electron microscopy, energy dispersive spectrometry and X-ray diffraction. The concentration of absorbed hydrogen was determined using an optical emission spectrometer with glow discharge for the GC alloys and using a hydrogen analyzer for the SPS alloys. The process of hydrogen evolution was observed by mass spectrometry for SPS alloys. The highest total amount of hydrogen was absorbed by the MgNi26 alloy both for both the GC and SPS alloys. The only hydriding product was MgH2 in the α- and γ-modification. Compared to commercial powder MgH2, the decomposition temperature was reduced by more than 200 °C, which can be ascribed to the catalytic effect of Mg2Ni and namely to the nanostructured magnesium formed after SPS.