Hydrogen solubility and diffusion studies of Zr-based AB<inf>2</inf> alloys and sol-gel encapsulated AB<inf>2</inf> alloy particles

Hydrogen solubility and hydrogen diffusion coefficients have been studied in Ti0.1Zr0.9(Mn0.9V0.1)1.1Fe0.5Ni0.5, Ti0.1Zr0.9Mn0.9V0.1Fe0.55Ni0.55 and (Ti0.1Zr0.9)1.1Mn0.9V0.1Fe0.5Co0.5 in the temperature range 450-650 °C with hydrogen gas pressure up to 100 mbar and hydrogen concentration up to 0.03 hydrogen atoms per formula unit. H2 absorption is exothermic, and the values of partial enthalpy of solution per H atom are in the range from -370 ± 10 meV to -466 ± 50 meV. The silica embedded AB2 alloy particles have been prepared by sol-gel technique. P-C isotherms of encapsulated AB2 alloy particles have been obtained in the pressure and temperature ranges 0-30 bar and 30-100 °C, respectively. Diffusion of H interstitials in sol-gel encapsulated Ti0.1Zr0.9Mn0.9V0.1Fe0.5Ni0.5, (Ti0.1Zr0.9)1.1Mn0.9V0.1Fe0.5Ni0.5 and (Ti0.1Zr0.9)1.1Mn0.9V0.1Fe0.5Co0.5 alloy particles have been studied between 500 and 650 °C with H2 gas pressure up to 100 mbar and H concentration up to 0.014 H atoms per formula unit. Diffusion coefficient (D) of H interstitials has been determined for all these samples from the kinetics of hydrogen absorption. The activation energies have been calculated from temperature dependence of diffusion coefficient and the values are in the range 416 ± 15-897 ± 50 meV. © 2006 Elsevier Ltd. All rights reserved.