High-pressure hydrogen loading in Ti₄₅Zr₃₈Ni₁₇ amorphous and quasicrystal powders synthesized by mechanical alloying

Amorphous and icosahedral phase (i-phase) powders, synthesized directly by mechanical alloying (MA) and after subsequent annealing, respectively, are hydrogenated at a temperature of 573 K and an initial pressure of 3.8 MPa. The i-phase powder contains a Ti₂Ni-type phase (fcc structure, lattice parameter, a = 1.23 nm) as a minor phase. Hydrogen cycling for the i-phase powder decreases the coherence length and enhances the formation of an fcc hydride phase, namely (Ti, Zr)H₂. The amorphous powder, which transforms to the fcc hydride after hydrogenation, is transformed primarily into a Ti₂Ni-type crystal phase and a small amount of the i-phase after hydrogen desorption. Hydrogen cycling and mechanical alloying in a hydrogen gas atmosphere dramatically reduces the loading time of hydrogen for both the i-phase and the amorphous powders.