IMC hydrides with high hydrogen dissociation pressure

Hydrogen sorption properties of a large variety of solid solutions on the base of ZrCr2 and TiFe2 intermetallic compounds are studied at pressures up to 300 MPa. Partial substitution of Cr by small amounts of Me = Al, Mn, Mo, Ni and B does not significantly change the H/M ratio of hydrides of the Ti(Cr1-xMex)(2-a) alloys with 0 < a < 0.2, whereas the substitution by Me = Si results in a steep decrease of this ratio. An increase in the concentration of the substituting metal inhibits the transformation of the studied hydrides from the initial Laves phase to a CaF2-type structure with increasing hydrogen pressure at a temperature of -50 degrees C. In the case of the ZrFe2 compound, substituting Zr by Dy and Y, and also substituting Fe by V, Cr, Mn, Ni, Cu and Mo decrease the equilibrium absorption and desorption pressures, unlike Ti substitution for Zr and Co substitution for Fe. Substituting Zr by Dy, Y and Ti, as well as substituting Fe by V, Cr, Ni and Cu decrease the hysteresis between the formation and decomposition pressures of the hydrides. In the case of Zr1-xTix(Fe1-yMey)(2) multicomponent alloys with Me = V and/or Ni, the decomposition pressure varies in a wide range of 0.5-250 MPa. Some of the investigated alloys can be used for designing metal hydride compressors. (C) 2011 Elsevier B.V. All rights reserved.