Hydrogen solubility and permeability of Nb–W–Mo alloy membrane

The alloying effects of molybdenum on the hydrogen solubility, the resistance to hydrogen embrittlement and the hydrogen permeability are investigated for Nb–W–Mo system. It is found that the hydrogen solubility decreases by the addition of molybdenum into Nb–W alloy. As a result, the resistance to hydrogen embrittlement improves by reducing the hydrogen concentration in the alloy. It is demonstrated that Nb–5 mol%W–5 mol%Mo alloy possesses excellent hydrogen permeability without showing any hydrogen embrittlement when used under appropriate hydrogen permeation conditions, i.e., temperature and hydrogen pressures.

Research highlights▶ The concept for alloy design of Nb-based hydrogen permeable membrane has been applied to Nb–W–Mo ternary alloy in order to improve further the resistance to hydrogen embrittlement and hydrogen permeability. ▶ The alloying effects of Mo on the hydriding properties of Nb–W alloy have been elucidated. ▶ The addition of Mo and/or W into niobium improves the resistance to hydrogen embrittlement by reducing the dissolved hydrogen concentration in the alloy. ▶ Nb–W–Mo alloy possesses excellent hydrogen permeability together with strong resistance to hydrogen embrittlement.