Effect of ball milling and cold rolling on hydrogen storage properties of nanocrystalline TiV1.6Mn0.4 alloy

The effect of high energy milling and cold rolling on the BCC solid solution TiV1.6Mn0.4 was investigated. The as-cast alloy presented a nanocrystalline structure with a crystallite size of 17 nm. After 5 h of milling a slight reduction of crystallite size was measured and the BCC solid solution lattice parameter was reduced from 3.082 Å to 3.061 Å. Cold rolling also had for effect a reduction of crystallite size and lattice parameter. The main effect of cold rolling was to produce a highly textured alloy along the (2 0 0) Bragg peak. The as-cast alloy could store a maximum of 3.48 wt.% of hydrogen at 423 K and has a reversible capacity of 1.8 wt.%. The ball -milled and cold rolled samples did not absorb hydrogen even after 10 hydrogenation/dehydrogenation cycles. Possible reasons why ball milled and cold rolled samples did not absorb hydrogen are discussed.