Effects of hydrogen on Ni47Ti44Nb9 shape memory alloy

The effect of hydrogen on the transformation characteristic and microstructure of NiTiNb shape memory alloy was investigated. Samples were charged with hydrogen by electrolysis for different time. DSC results showed that new reversible transformation peaks around 110°C appeared, and the transformation enthalpies of the thermal peaks increased with the increasing charging time. They had a narrow hysteresis (almost 5°C) which was quite a novel characteristic for large hysteresis NiTiNb alloy. X ray diffraction (XRD) results illustrated that the {110} diffraction peak of the b-Nb phase shifted to lower angles with a corresponding lattice parameter increased from 2.3356 Å to 2.4427 Å (corresponding to nearly 14% of volume increase), while the lattice parameter of the {110}_B2 diffraction peak of NiTi alloy increased from 2.1361 Å to 2.1453 Å (corresponding to just 1.3% of volume increase).