HYDROGENATION AND PHASE-STRUCTURE OF TI-FE-V ALLOYS

Hydrogenation behavior and phase structures of some Ti-Fe-V ternary al loys were studied. Three different crystal structures, namely, a bcc, a CsCl-type and a C14 Laves phase structure were found. The atoms in t he C14 Laves phase TiFe2 could be partially substituted by vanadium at oms without changing its structure. It was found that the C14 Laves ph ase structure region was expanded nearly to the center of the Ti-Fe-V ternary phase diagram. Lattice parameters of the alloys increased almo st in proportion with increasing average atomic size of the constituen t elements. It was also found that hydrogen storage capacity at a cons tant pressure increased with increasing the degree of vanadium substit ution. The pressure-composition (P-C) isotherms of the C14 Ti-Fe-V all oys strongly sloped and they had no flat plateau. The storage capacity of C14 Laves phase Ti-Fe-V alloy was optimized to be 1.0 at the chemi cal composition of TiFeV0.7.