Synthesis of Nanostructured TiFe Hydrogen Storage Material by Mechanical Alloying via High‐Pressure Torsion

TiFe as a room‐temperature hydrogen storage material is usually synthesized by ingot casting in the coarse‐grained form, but the ingot needs a thermal activation treatment for hydrogen absorption. Herein, nanograined TiFe is synthesized from the titanium and iron powders by severe plastic deformation (SPD) via the high‐pressure torsion (HPT). The phase transformation to the TiFe intermetallic is confirmed by X‐ray diffraction, hardness measurement, scanning/transmission electron microscopy, and automatic crystal orientation and phase mappings (ASTAR device). It is shown that the HPT‐synthesized TiFe can store hydrogen at room temperature with a reasonable kinetics, but it still needs an activation treatment. A comparison between the current results and those achieved on high activity of HPT‐processed TiFe ingot suggests that a combination of ingot casting and SPD processing is more effective than synthesis by SPD to overcome the activation problem of TiFe.