Outstanding shortening of the activation process stage for a TiFe-based hydrogen storage alloy

Hydrogen solid storage in intermetallic compounds has attracted great attention in the recent decades; TiFe-based metal hydride is one of the most important candidate materials to hold atomic hydrogen because of its significant storage capacity (about 1.9 wt. %) and its moderate operating pressure and temperature. The main hindrance to an effective and large use of this metal forming hydride is the difficult activation process i.e. the initial hydriding attempt. In this paper an experimental study about the first hydrogenation process of TiFe_0.9Mn_0.1 is carried out with a Sievert apparatus. At first, powder fabrication protocol then materials and methods used for the experimental characterizations are described. Secondly, a literature survey is presented about the activation processes of TiFe based alloys. Finally experimental results, discussions and conclusions are exposed. Those results lead to a comparison between the hydrogenation behaviors of two TiFe_0.9Mn_0.1 powder types: the 'as received' powder and the same powder after a thermo-chemical treatment. A wide improvement in the hydrogen activation response is noticed when the powder is submitted to this thermo-chemical treatment under specific operating conditions of gas pressure, temperature and time-duration. Plotted PCI curves and XRD patterns demonstrate that the material bulk is not affected by this thermo-chemical treatment. Then, the operating conditions are optimized, and SEM visualizations are performed in order to point out the effects of the treatment on the surface properties of TiFe_0.9Mn_0.1 particles. At the end, a conclusion summarizes the main results and outlines the perspectives of such thermo-chemical treatment.