Measurement of hydrogen permeability of pure Nb and its alloys by electrochemical method

Niobium metal is one of the promising materials for hydrogen permeable membranes because of the highest hydrogen permeability among the 5A group metals including V and Ta. In the present study, using a limiting current method, the hydrogen permeability was measured precisely for the first time with pure Nb and Nb-5 mol%M binary alloys. Here, M were 4d transition metals, Zr, Mo, Ru and Pd. The measured hydrogen permeability of pure Nb agreed well with the value calculated from the diffusion coefficient and the hydrogen solubility. Also, it was found that the hydrogen permeability of niobium increased by the addition of Zr and Pd, but decreased by the addition of Mo and Ru.