The H mass density of bcc Ti35Cr65-xVx alloys (x = 18, 22) was investigated as a function of pressure at various temperatures by tracing P-C isotherms from which the formation enthalpy of the γ hydride was derived (ΔH = -392kJ/mol for Ti35Cr43V22 and ΔH = -35kJ/mol for Ti35Cr47V18). Internal friction measurements revealed the existence of a broad H Snoek-type relaxation at around 150K (f ≅ 1kHz), which was used to deduce the H mobility. Combined Snoek and high-temperature absorption data indicated that:

Ti35Cr47V18:      D(m2/s) = 4 x 10-7exp[-0.32(eV)/kT]

and Ti35Cr43V22:      D(m2/s) = 2 x 10-7exp[-0.34(eV)/kT]

X-ray diffraction patterns confirmed the fcc lattice structure of the hydride while differential scanning calorimetry and thermal desorption spectroscopy data exhibited peaks which were attributed to structural transitions of the hydrides.

Hydrogen-Storage Capacities and H Diffusion in BCC TiVCr Alloys. G.Mazzolai, B.Coluzzi, A.Biscarini, F.M.Mazzolai, A.Tuissi, F.Agresti, S.L.Russo, A.Maddalena, P.Palade, G.Principi: Journal of Alloys and Compounds, 2008, 466[1-2], 133-9