INTERNAL FRICTION PEAKS IN AMORPHOUS Pd₈₀Si₂₀ ALLOYS

Abstract
Two internal friction peaks were observed in amorphous Pd₈₀Si₂₀ alloys with a conventional torsion pendulum in ascending temperatures. The peak temperature of Peak I (˜390°C) was found to be independent of the frequency used but very sensitive to the heating rate of the specimen. The height of this peak increased with the decrease of frequency. The peak temperature of Peak II (546-562°C) changed with frequency as well as with heating rate. Both peaks disappeared during cooling from 600°C to room temperature and they did not reappear when the same specimen was again heated up to 600°C. Differential scanning calorimetric measurements showed a single exothermal peak at 400°C and from the shape of this peak the temperature of crystallization may be defined at 392°C which corresponds to the peak temperature of the internal friction Peak I. The phase transition in the temperature range of Peak II is "athermal" and its behaviour and mechanism are more complicated.