Synthesis and Characterization of TiFe0.7-xMn0.3Vx (x=0.05, and 0.1) and   Ti1-yTayFe0.7Mn0.3 (y=0.2, and 0.4) Nanostructured Metal Hydrides for Low   Temperature Applications
  Metal hydrides (MH) are often preferred to absorb and desorb hydrogen at ambient temperature and pressure with a high volumetric density. These hydrogen storage alloys create promising prospects for hydrogen storage and can solve the energetic and environmental issues. In the present research work, the goal of our studies is to find the influence of partial substitution of small amounts of vanadium and tantalum on the hydrogenation properties of TiFe0.7-xMn0.3Vx (x=0.05, and 0.1) and Ti1-yTayFe0.7Mn0.3 (y=0.2, and 0.4) alloys, respectively. The nominal compositions of these materials are TiFe0.65Mn0.3V0.05, TiFe0.6Mn0.3V0.1, Ti0.8Ta0.2Fe0.7Mn0.3, and Ti0.6Ta0.4Fe0.7Mn0.3. All samples were synthesized by arc-melting high purity elements under argon atmosphere. The structural and microstructural properties of the samples were studied by using XRD and SEM, respectively, while the corresponding microchemistry was determined by obtaining EDS measurements at specific regions of the samples. Mapping was obtained in order to investigate atomic distribution in microstructure. Moreover, to ensure the associations between the properties and structure, all samples were examined by an optical microscope for accessional characterization. From all these microscopic examinations a variety of photomicrographs were taken with different magnifications. The hydrogenation properties were obtained by using a Magnetic Suspension Balance (Rubotherm). In this equipment, the hydrogen desorption and re-absorption, can be investigated at constant hydrogen pressures in the range of 1 to 20 MPa (flow-through mode). At least 3.43 wt. % of absorbed hydrogen amount was measured while the effect of substitutions was investigated at the same temperature. 
N.G. Anagnostou, S.S. Makridis, E.S. Kikkinides, C.N. Christodoulou   and A.K. Stubos
cond-mat.mtrl-sci