Hydriding–dehydriding cycling behavior of magnesium–nickel–iron oxide alloy

By measuring the absorbed hydrogen quantity as a function of number of cycles, cycling characteristics of the Mg–15 wt%Ni–5 wt%Fe2O3 alloy was investigated. The sample was hydriding–dehydriding cycled 150 times. The absorbed hydrogen quantity decreased as the number of cycles increased from the second to the 150th cycle. The Ha value varied almost linearly with the number of cycles. The degradation rate from n = 1 to n = 100 is 0.01201 wt%/cycle for the hydriding reaction time of 10 min, and 0.00860 wt%/cycle for the hydriding reaction time of 60 min. After the 150th hydriding–dehydriding cycle, Mg, Mg2Ni, Mg(OH)2, MgO, and Fe were observed. The phases were analyzed by Rietveld analysis from the XRD patterns of the Mg–15Ni–5Fe2O3 alloy after 150th hydriding–dehydriding cycles. The crystallite size and strain of Mg were then estimated by Williamson–Hall technique.