On the amorphization behavior and hydrogenation performance of high-energy ball-milled Mg₂Ni alloys

Amorphous Mg₂Ni alloy was prepared by high energy ball-milling starting with polycrystalline Mg₂Ni which was prepared with the help of a metallurgy method by using a SPEX 8000D mill. The microstructural and phase structure characterization of the prepared materials was performed via scanning electron microscopy, transition electron microscope and X-ray diffraction. The thermal stabilities were investigated by differential scanning calorimetry. The apparent activation energies were determined by means of the Kissinger method. The first and second crystallization reactions take place at ~ 255 C and ~ 410 C, and the corresponding activation energy of crystallization is E_a1 = 276.9 and E_a2 = 382.4 kJ/mol, respectively. At 3 MPa hydrogen pressure and 250 C, the hydrogen absorption capacities of crystalline, partially and fully amorphous Mg₂Ni alloy are 2.0 wt.%, 3.2 wt.% and 3.5 wt.% within 30 min, respectively.