Formation of an amorphous (a-) Nb20Ti40Ni40 alloy by rapid quenching and its crystallization behavior were investigated by X-ray diffraction, differential scanning calorimetry and scanning electron microscopy. The B2-TiNi phase was firstly crystallized and the remaining amorphous (a-) phase subsequently decomposed into the bcc-(Nb,Ti) + B2–TiNi phases. The crystallized (c-) Nb20Ti40Ni40 samples obtained by annealing above 1173K were ductile and insusceptible to hydrogen embrittlement between 598 and 673K. Hydrogen permeability at 673K for the a- and c-Nb20Ti40Ni40 alloys were 8.1 x 10−9 and (3.0–4.8) x 10−9molH2/m/s/Pa0.5, respectively. The 673K permeability increased with the increase in the diameter of the bcc-(Nb,Ti) phase, although this led to poor resistance to hydrogen embrittlement. The lower hydrogen permeability of the c-Nb20Ti40Ni40 alloy was due to its lower hydrogen diffusivity. The present work demonstrated that rapid quenching and subsequent annealing were useful to prepare thermally stable Nb–TiNi hydrogen permeation alloy membranes.

Hydrogen Permeation in Rapidly Quenched Amorphous and Crystallized Nb20Ti40Ni40 Alloy Ribbons. K.Ishikawa, Y.Seki, K.Kita, M.Matsuda, M.Nishida, K.Aoki: International Journal of Hydrogen Energy, 2011, 36[2], 1784-92