KINETIC-STUDY OF THE HYDROGEN ABSORPTION IN THE ZR(ALXFE1-X)2 SYSTEM

The hydriding kinetic behavior of Zr(AlxFe1-x)2, 0.5 less-than-or-equal-to x less-than-or-equal-to 0.75, specimens was examined at pressures up to 70 atm and temperatures up to 573 K. Quantitative information was obtained only for Zr(Al0.5Fe0.5)2 and partly for Zr(Al0.6Fe0.4)2. The results were interpreted in terms of a constant velocity movement of the hydride-metal boundary. A significant increase of the hydrogenation activation energy was found for Zr(Al0.5Fe0.5)2 and Zr(Al0.6Fe0.4)2 with respect to the previously investigated Zr(Al0.2Fe0.8)2. This was manifested by a corresponding two order magnitude decrease of the hydride propagation velocities at room temperature. We regard the variation in hydriding kinetics, stability and hydrogen capacity across the Zr(AlxFe1-x)2-H2 system as an indication of a possible kinetic effect on the hydrogen absorption in the Al-rich compounds.