Internal-friction peaks of hydrogen in amorphous and crystalline Co33Zr67

The hydrogen-induced internal-friction spectra, for hydrogen concentrations below 10 at.%, are measured in the different crystallization stages of amorphous Co 33 Zr 67 at various temperatures and frequencies using the vibrating-reed technique. Four internal-friction peaks are observed and analysed with respect to the underlying relaxation mechanisms. Three of them can be attributed to Snoek-type relaxation processes caused by thermally activated jumps of H atoms between neighbouring Zr 4 tetrahedral sites in (i) the amorphous phase, (ii) the grain boundaries of a metastable, nanocrystalline state of cubic CoZr 2 , and (iii) the crystal lattice of the tetragonal CoZr 2 equilibrium phase, respectively. Structural and microstructural implications of these results are outlined.