The solubility and diffusivity of H in the cubic high-temperature phase of the shape-memory alloy were studied, at temperatures of between 500 and 950C, under H gas pressures of up to 1.3bar, and for H/NiTi ratios of up to 0.027. The H was present in interstitial solid solution, and the absorption process was exothermic; with an enthalpy of solution of -0.183eV/Hatom. The diffusion data (figure 24) could be described by the expression:

D (cm2/s) = 4.7 x 10-3exp[-0.48(eV)/kT]

The alloy hydride was produced during experiments which were performed at 500K in a H gas pressure of 150bar.

Hydrogen Solubility and Diffusion in the Shape-Memory Alloy NiTi. R.Schmidt, M.Schlereth, H.Wipf, W.Assmus, M.Müllner: Zeitschrift für Physikalische Chemie, 1989, 164[1], 803-8. See also: Journal of Physics - Condensed Matter, 1989, 1[14], 2473-82