Microstructure and hydrogen permeation of cold rolled and annealed Nb40Ti30Ni30 alloy

The ultimate rolling reduction rate (ru) of the as-cast Nb–TiNi alloys was evaluated by measuring the thickness changes in cold rolled samples. Furthermore, the effects of cold rolling and subsequent anneal on hardness, microstructure, hydrogen permeability (Φ) and hydrogen flux J of the as-cast Nb40Ti30Ni30 alloy (mol%) were examined by a Vickers hardness tester, a scanning electron microscope (SEM), and a mass flow meter, respectively. The value of Φ for the Nb40Ti30Ni30 alloy was reduced with increasing rolling reduction rate and attained to one third of the original one by 50% rolling reduction, but recovered to the original one by anneal at 1373 K for 605 ks. Hydrogen flux J varied inversely proportional to the membrane thickness at 673 K. J of 12 ccH2/cm2/min was attained for the sample with the thickness of 120 μm. The present work has demonstrated that rolling and the subsequent anneal are effective and useful for the preparation of the hydrogen permeation Nb–TiNi alloy membrane.