HYDROGEN ABSORBING-DESORBING PROPERTIES AND CRYSTAL-STRUCTURE OF THE ZR-TI-NI-MN-V AB(2) LAVES PHASE ALLOYS

The effect of the substitution of Ti for the Zr (A) site and V for the Mn (B) site of ZrNi1.3Mn0.7 on the hydrogen absorbing-desorbing properties and crystal structure was studied by measuring pressure-composition (PC) isotherms at 313 K and by X-ray powder diffraction measurements. There exist three phases, the C14 and C15 Laves phases and the BCC solid solution phase in twelve alloys studied (Zr1-xTixNi1.3Mn0.7-yVy, x = 0, 0.1, 0.2, 0.5; y = 0, 0.1, 0.2, 0.4, 0.7). The lattice parameter of the alloys containing the C15 Laves phase decreased as Ti (A-site) content was increased; contrarily it increased as V (B-site) content was increased. The PC isotherms of the alloys with the C15 Laves phase indicated that the equilibrium plateau pressure increased with increasing Ti content, but decreased with increasing V content. The hysteresis observed in the PC isotherm was reduced by substitution of Ti and V in the A and B sites, respectively.