Eleventh International Conference on Internal Friction and Ultrasonic Attenuation in Solids
J. Phys. IV France 06 (1996) C8-39-C8-42
Anelasticity of Polycrystalline Yttrium at Low Concentrations of H and OG. Cannelli1, R. Cantelli2, F. Cordero3, F. Trequattrini2 and A. Sermoneta2
1 Dipartimento di Fisica, Università della Calabria, 87036 Arcavacata di Rende (CS), Italy
2 Dipartimento di Fisica, Università di Roma "La Sapienza", Piazzale A. Moro, 00185 Roma, Italy
3 Istituto di Acustica "O.M. Corbino", Consiglio Nazionale delle Ricerche, Via Cassia 1216, 00189 Roma, Italy
In order to clarify the nature of the numerous thermally activated processes occurring in yttrium, the anelastic relaxation spectrum of polycrystalline samples has ben investigated between 1.1 and 600 K in the kHz range, by varying the concentration of interstitial hydrogen and oxygen and in presence of plastic deformation. Besides the main dissipation peak around 300 K due to the formation /dissolution of H pairs and the peak at liquid He temperature attributed to H tunnelling, four processes have been observed. The processes below 300 K can be interpreted by mechanisms involving hydrogen trapped by oxygen, and dislocations dragging interstitial H, whilst the large relaxation observed around 450 K has to be ascribed to oxygen motion in solid solution.
© EDP Sciences 1996