Abstract
In order to develop high hydrogen permeability alloys, structural changes induced by hydrogenation, microstructures and hydrogen permeability Φ were investigated for samples on the straight line connecting the eutectic and the primary phase in the Nb–Ti–Ni phase diagram. Φ was measurable in the alloys containing much amount of the eutectic phase, indicating that the eutectic microstructure suppresses the hydrogen embrittlement. The value of Φ increased with increasing Nb content and the volume fraction of the primary (Nb,Ti) phase. The most Nb-rich Nb68Ti17Ni15 alloy showed the highest Φ of 4.91×10−8 (mol H2m−1 s−1 Pa−0.5) at 673 K, which is 2.5 times higher than that of the Nb39Ti31Ni30 alloy, which has been reported to be highest in the Nb–Ti–Ni alloys. The present work demonstrated that the hydrogen permeable alloys are extended on the straight line connecting the eutectic and the primary phase to the Nb-rich side in the Nb–Ti–Ni system.
