Dislocation Relaxation Peaks in High-Purity Molybdenum Single Crystals

The internal friction at 25 kHz is investigated between 77 and 300 K on high-purity molybdenum single crystals of different orientations after plastic deformation. After high-temperature deformation the α-peak at 130 K is observed. After low-temperature deformation two damping peaks appear; the α1-peak at 100 K and the α2-peak between 140 and 200 K. The β-peak is observed at 370 K after hydrogen annealing, plastic deformation, and low-temperature annealing. It is suggested that the α1-peak is related to kink-pair formation on non-screw (71°) dislocations and the α2-peak to kink migration on screw dislocations. The α-peak appears as a composed maximum with the two components α1 and α2. The β-peak is attributed to the interaction of hydrogen with screw dislocations.