CORRELATION BETWEEN STRUCTURE AND HYDRIDING BEHAVIORS IN LAVES PHASES- ZR(MXCR1-X)2, M=FE, NI

In the MgZn2 hexagonal Laves phases, pseudo-binary compounds are prepa red by changing M and Y in the formula: Zr(MxY1-x)2 M = Fe, Ni, Co, V and Y = Cr, Mn, V. Normally there is a linear decrease in the cell vol ume with increasing x. Replacement of Fe by Ni in the same proportion produces an anomalous change in the H-2 equilibrium pressure by refere nce to what can be predicted from the volume change. In fact, Ni subst ituted Laves Phases have the expected properties if the comparative pa rameter is no longer the cell volume but the tetrahedral H-2 host site volume. With this last criteria, both thermodynamic and kinetic param eters can be expressed by linear functions.