High precision measurement of torsion fiber internal friction at cryogenic temperatures

The vibrating reed technique has been used to investigate the Zr69.5Cu12Ni11Al7.5 glass forming alloy. The phase transformations of the material, as can be seen through the changes of the resonance frequency of the sample as a function of temperature, have been studied and the results have been compared with TEM and DSC measurements confirming the development, above Tg, of a metastable quasicrystalline state prior to crystallisation. Hydrogen-induced damping peaks were then observed in the different phases of the material with particular attention to the quasicrystalline state, where it seems that the microscopic reorientation mechanism responsible for the internal friction peaks should be similar to the one already known in the amorphous phase (hydrogen jumps between tetrahedral sites). Shortly after crystallisation, three damping peaks were observed, two of which are attributed to relaxation processes (Zener-type or intercrystalline Gorsky effect) taking place in the tetragonal CuZr2 phase.