Isotope effect in internal friction peak caused by hydrogen in amorphous Pd-Si

The isotope effect of H and D on the internal friction peak in glassy alloys of Pd80Si20 was studied. The samples were prepared by melt spinning. The strips of about 15 mm long were cut directly from the as-prepared ribbon. The samples were mechanically clamped, and the internal friction and Young's modulus were measured in a vibrating reed apparatus. The annealing of the samples and later on the sorption and desorption of H and D were done in situ. Charging was done under approximately 1.6 atmospheric pressure of H or D at the ambient temperature. The effects of the dissolved H and D atoms were clearly seen in the temperature dependence curve of the interval friction. The maxima were seen around 200 K. The height of an internal friction peak depended generally on the concentration of relaxation centers and the size of the elastic dipole. The relaxation was also seen in the measurement of elastic modulus. The activation energy differed in the case of H and D, and indicated a large isotope effect. (Kato, T.)