ON THE STRUCTURAL AND HYDROGEN DESORPTION PROPERTIES OF THE ZR(CR1-XCUX)2 ALLOYS

X-ray powder diffraction studies of the Zr(Cr1-xCux)2 system revealed the existence of a single-phase region up to the composition Zr(Cr0.5Cu0.5)2. All the ternary alloys crystallize with a Friauf-Laves structure of the MgCu2 type, differing from the binary compound ZrCr2 which exhibits polymorphism and crystallizes with the hexagonal structure of the MgZn2 type and the cubic structure of the MgCu2 type. It was also found that single-phase alloys react readily with hydrogen to form hydrides having 2-3 hydrogen atoms per formula unit under a hydrogen pressure of 1.0 MPa at room temperature. Pressure-composition hydrogen desorption isotherms were determined over the temperature range 296-473 K. In general, the dissociation equilibrium pressure increases and hydrogen capacity decreases with increasing copper content. The hydrogen sorption properties of the systems described in this paper and of similar systems based on ZrCr2 are briefly discussed.