Improvement of Hydrogen Absorption Performance of Mechanically Alloyed Mg<SUB>2</SUB>Ni Powders by Silver Doping

Abstract

In the present study, hydrogen-absorbed Mg2Ni intermetallic powders were prepared by mechanical alloying under an Ar atmosphere. Modification of the Mg2Ni powders was attempted by adding silver (0.5, 1.0, 2.5, and 5.0 at%) into starting elemental powder mixtures. The asmilled powders were examined as a function of milling time by X-ray diffraction and synchrotron X-ray absorption techniques. In addition, the hydrogen absorption performance of the 15 h as-milled powders were evaluated. The experimental results show that (Mg2Ni)100� xAgx powders exhibited a mixture of Mg2Ni, magnesium and nickel solid solutions after 15 h of milling treatment. The maximum hydrogen absorption content and reversible hydrogen content of 15 h as-milled Mg2Ni powders was 3.14 and 2.40 mass%, respectively. An improvement of hydrogen absorption properties can be noticed by doping silver, but the less silver addition the better performance. In the present study, (Mg2Ni)99:5Ag0:5 exhibited the best hydrogen absorption properties where the maximum hydrogen absorption content and reversible hydrogen content was increased significantly to 3.93 and 3.14 mass% respectively. More than 25% improvement of hydrogen absorption for Mg2Ni intermetallic powders was achieved by doping silver. [doi:10.2320/matertrans.48.1113]