Formation of BCC TiFe hydride under high hydrogen pressure

We investigated the hydrogenation of a binary TiFe alloy at 5 GPa and 600 °C by in situ synchrotron radiation X-ray diffraction measurements. After formation of a solid solution of hydrogen in TiFe, an order–disorder phase transition in the metal lattice of TiFe occurred, which yielded a BCC TiFe hydride. The unit cell volume of the BCC hydride increased by 21.0% after the hydrogenation reaction. The volume expansion was larger than that of a γ-hydride TiFeH_1.9 prepared by hydrogenation near ambient conditions.