Solubility and diffusion of hydrogen in AB2-type Laves phase alloys

Solubility of H2 gas and diffusion of H interstitials were studied in Ti0.1Zr0.9Mn0.9V0.1Fe0.5Ni0.5, (Ti0.1Zr0.9)1.1Mn0.9V0.1Fe0.5Ni0.5 and Ti0.1Zr0.9Mn0.9V0.1Fe0.5Co0.5 alloys with C14 hexagonal structure. Data were taken between 400 and 600 ° C, for H2 gas pressures up to 100 mbar and H concentrations up to 0.012 H atoms per host-metal formula unit (solid solution phase). H2 absorption is exothermic, and the partial enthalpy of solution per H atom is −(210±10) and −(248±10)  meV for the two alloys Ti0.1Zr0.9Mn0.9V0.1Fe0.5Ni0.5 and (Ti0.1Zr0.9)1.1Mn0.9V0.1Fe0.5Ni0.5, respectively. The diffusion coefficient of the H interstitials was determined for all three samples from the kinetics of H2 gas absorption. At 500 ° C, the diffusion coefficients are ∼5×10−5  cm2s−1, with activation energies between 292 and 423 meV.