Relationship between microstructure and hydrogen permeation properties in the multiphase Ni21Ti23Nb56 alloy membranes

The cooling rate has significant effects on the microstructure of Ti-Ni-Nb-based multiphase alloys. In the present study the effect of the microstructure on the hydrogen permeation properties of multiphase Ni21Ti23Nb56 alloy membrane was systematically investigated. Our result suggested a complementary relation between the quantity of the primary bcc-(Ti, Nb) solid solution phase and hydrogen permeation properties. The Ni21Ti23Nb56 alloy with about 70% surface fraction of primary phase bcc-(Nb-Ti) solid solution showed the higher hydrogen permeability value of 7.48 × 10−8 mol/m s Pa1/2 at 450 °C, which is higher in value compared to Ti-Ni-Nb-based multiphase alloys reported in published works. Moreover, comparison between the present experimental data and the literature was analyzed to illustrate the capability of the proposed control of microstructure membrane for the improvement of the hydrogen permeation properties of Ti-Ni-Nb -based multiphase alloys.