Sievert's type apparatus using high pressure autoclave was employed to study the hydrogen storage properties of intermetallic compound FeTi. The effect of the alloying element, Mn, on the hydrogen storage properties of FeTi alloy was investigated by substituting Mn for Fe in FeTi alloy.
The alloy $Fe_{0.98}Ti_{1.02}$ reacted directly with hydrogen to form, in succession, hydrides of the compositions $Fe_{0.98}Ti_{1.02}-H_{1.04}$ and $Fe_{0.98}Ti_{1.02}H_{1.92}$ at 0℃. Both hydrides had dissociation pressure of over 1 atmosphere at 0℃. The relative partial molal enthalpies of hydrogen had the values of -3.11 kcal/g.atom at the composition of $Fe_{0.98}Ti_{1.02}H_{0.8}$ and -3.89 kcal/g.atom at the composition of $Fe_{0.98}Ti_{1.02}H_{1.04}$. The hysteresis effect was observed, the absorption isotherm of pressure vs. composition being about 10 atmospheres higher than the desorption isotherm at the composition of $Fe_{0.98}Ti_{1.02}H_{0.8}$. The Mn alloyed specimen tended to be more easily cracked than FeTi alloy after hydriding. But the addition of Mn in FeTi alloy faciliated activation process without seriously reducing the hydrogen storage capacity of this alloy.
