Mechanical energy losses due to the movement of dislocations in molybdenum at high temperatures (0.3Tm)

Damping measurements were performed, at around 1 Hz, in high purity single crystalline molybdenum from room temperature up to 1273 K. The results showed that the intensity of the damping peak at around 840-1050 K depended on the degree of plastic deformation at room temperature. Moreover the peak temperature and activation energy of this relaxation increased with the temperature of the previous annealing of the sample, and was independent of the crystal orientation. In addition, once the damping peak appeared after annealing, the damping values were independent of the amplitude of oscillation. Possible physical mechanisms involving dislocations interaction are discussed.