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Because of its low density, storage of hydrogen in the gaseous and liquids states possess technical and economic challenges. One practical solution for utilizing hydrogen in vehicles with proton-exchange fuel cells membranes is storing hydrogen in metal hydrides. Magnesium hydride (MgH2) remains the best hydrogen storage material due to its high hydrogen capacity and low cost of production. Due to its high activation energy and poor hydrogen sorption/desorption kinetics at moderate temperatures, the pure form of MgH2 is usually mechanically treated by high-energy ball mills and catalyzed with different types of catalysts. These steps are necessary for destabilizing MgH2 to enhance its kinetics behaviors. In the present work, we used a small mole fractions (5 wt.%) of metallic glassy of Zr70Ni20Pd10 powders as a new enhancement agent to improve its hydrogenation/dehydrogenation behaviors of MgH2. This short-range ordered material led to lower the decomposition temperature of MgH2 and its activation energy by about 121 °C and 51 kJ/mol, respectively. Complete hydrogenation/dehydrogenation processes were successfully achieved to charge/discharge about 6 wt.%H2 at 100 °C/200 °C within 1.18 min/3.8 min, respectively. In addition, this new nanocomposite system shows high performance of achieving continuous 100 hydrogen charging/discharging cycles without degradation.

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We have found that a cyclic crystalline–amorphous phase transformation can occur in Co75Ti25 alloy powder when subjected to ball milling. The results have shown that a single amorphous phase of Co75Ti25 is obtained after 11 ks of mechanical alloying (MA) time. This amorphous phase transforms into a new metastable phase of bcc-Co3Ti upon milling for 86 ks. The bcc-Co3Ti is thermally stable and does not transform to any other phase(s) upon heating up to 1300 K. It however returns to the same amorphous phase of Co75Ti25 upon milling for 360 ks. Further milling leads to the formation of crystalline and/or amorphous phases depending on the MA time.

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