Hydriding kinetic properties in massive Zr(AlxCo1-x)2 samples as a function of the Al content

The hydriding kinetics of the Zr(AlxCo1-x)(2) (0.1less than or equal toxless than or equal to0.5) system was monitored for massive rectangular parallelepiped samples utilizing hydrogen pressures up to 80 atm and temperatures between 238 K and 293 K. The use of temperatures higher than 20 degreesC was restricted in most cases due to the appearance of self-heating effects. The experimental data were fit to a shrinking core model. The apparent activation energies, E-a, for each composition are derived from the temperature dependence of the reaction rate constants at given P/P-eq ratios, where P is the applied experimental hydrogen pressure and P-eq is the equilibrium pressure at a given temperature. A minimum of E-a was detected for the x=0.25 compound. Similar behavior has been also observed in other Al-containing pseudobinary compounds, but it seems that this effect is most prominent in the Zr(AlxCo1-x), system. (C) 2002 Elsevier Science B.V. All rights reserved.