Fabrication of Mg2NiHx from Mg and Ni chips by hydrogen induced planetary ball milling

For manufacturing Mg2NiHx hydrogen absorbing materials economically, Mg and Ni chips were mechanically alloyed under 2 MPa hydrogen atmosphere by plan etary ball milling. The homogeneous Mg2NiHx was formed after 72 h mechanica l alloying (MA) in both 30:1 and 66:1 BCR (ball to chips mass ratio). The m aximum absorbed hydrogen content of the Mg2NiHx reached 3.9 mass% after 48 h MA in 30:1 BCR and the dehydriding reaction of them started around 473 si milar to 503 K from the result of TG analysis. On the other hand, in 66:1 B CR, the fully hydrogenated alloys were obtained after 96 h MA, the total hy drogen content was 2.25 mass% and the dehydriding temperature was around 45 3 similar to 493 K. The composite phase obtained after 96 h MA in 66:1 BCR is composed of the nanocrystalline and amorphous phases, the structure of w hich seems to be the reason of the improved hydriding and dehydriding kinet ics. It was deduced that the conditions of BCR affected strongly the synthe sis of the Mg2NiHx.