B2-phase formation and hydriding properties of (Mg_1-xAl_x)Ni (x= 0~0.5)

Crystalline forming abilities of the alloys (Mg_1-xAl_x)Ni were systematically examined by mechanical alloying of Mg-rich compositions ranging from x=0 to x≈0.5. A crystalline phase with small crystallites of B2(CsCl)-type structure was firstly found to be formed in the alloys with x=0.3, 0.4 and 0.5, even in the as-alloyed state. This crystalline phase was thermally stable, and was able to interstitially dissolve hydrogen atoms without any structural transformation. These results indicate that the alloys can be regarded as a new series of hydrogen storage materials in the Mg-Ni system.