Improvement of hydrogen absorption performances of mechanically alloyed Mg₂Ni powders by water cooling

In the present study, Mg₂Ni intermetallic powders were prepared by mechanical alloying from elemental magnesium and nickel under an Ar atmosphere with or without water cooling treatments. Two different cooling temperature ranges were used to modify the hydrogen absorption properties of the intermetallic Mg₂Ni. The powders milled with or without water cooling were examined as a function of milling time by X-ray diffractometry. Then the hydrogen absorption performance of the 15 h as-milled powders were evaluated. The experimental results show that all the as-milled Mg₂Ni powders exhibited a mixture of Mg₂Ni, magnesium and nickel solid solutions. The maximum hydrogen absorption content of 15 h as-milled Mg ₂Ni powders was increased from 3.14 mass% to 3.83 mass% by cooling treatment in a temperature range of 264-267 K. The reversible hydrogenation content was also increased from 2.40 mass% to 3.03 mass% in the same cooling temperature range. More than 20% improvement of hydrogen absorption for Mg ₂Ni intermetallic powders was achieved by water cooling treatment.