Hydride Formation of Intermetallic Compounds of Titanium-Iron, -Cobalt, -Nickel and -Copper

Abstract

Intermetallic compounds of TiFe, TiCo, Ti2Ni, TiNi, Ti2Cu, TiCu and TiCu, react directly with hydrogen to form the hydrides. The relative partial molar enthalpies of hydrogen for TiFeHo., and TiCoH05 determined from the dissociation isotherms (Figs.2 and 3) are -37 kcalfmol and -3.7 kcal/mol, respectively. Thus, the hydride of TiCo is more stable than that of TiFe. Like TiFeH, , a, stoichiometric compound of TiCoH, has a tetragonal structure with a =6.14 A, c=9.06 A. Below 270°C TiNi forms an interstitial hydride TiNiH"which is more stable than those of TiFe and TiCo, but at about 500°C it decomposes into TiFI, and TiNi3 at the hydrogen pressure of 130 atm. Similar decomposition reaction is also observed when Ti2Ni, Ti2Cu, TiCu and TiCu3 are hydrided. Ti2Cu, TiCu and TiCu3 decompose simply into TiFI, and Cu.