Structure change of Pb-Sn melts explored with the improved internal friction technique

During a continuous heating process, the internal friction of liquid Pb-Sn alloys is measured by an improved torsion pendulum. A peak is observed at the temperature range from 500degreesC to 800degreesC. The position of the peak does not change with frequency. The height of the peak increases with heating rate, but decreases with frequencies. This character is the same as that of solid phase transitions. The position of the peak varies with chemical composition of the alloy. A subsequent peak is observed in liquid non-eutectic alloys. This indicates that the occurrence of structure transition is possible in liquid Pb-Sn alloys. Through differential thermal analysis, it is found that the temperature range is similar for the thermal peak and the internal friction peak in the same sample. This will further confirm that the internal friction peak may originate from structure transition.