The decomposition of the motion, of flexible dislocation lines in the Peierls potential of crystals, into 4 classes of almost independent degrees of freedom was considered. It was applied to the calculation of the equilibrium density of kinks in the presence of so-called geometrical kinks. The theory of mechanical relaxation, by kink-pair generation, was generalized so as to include the effects of geometrical kinks and internal stresses. The prediction that non-Debye features of relaxation, such as the so-called extra width of peaks in the temperature dependence of internal friction, should increase with decreasing measuring frequency agreed with experiments on Bordoni relaxation in Cu. In most face-centered cubic metals, kink-pair generation on dislocations with Burgers vectors of a/2<110> running along <110> or <112> gave rise to 2 rather broad relaxation peaks (Bordoni and Niblett–Wilks, respectively). In Al, the relaxation processes of 0°, 60°, 90° and 30° dislocations appeared in 4 well-separated internal-friction maxima. In this sequence, they were attributed to the Bordoni peak, the Niblett–Wilks (so-called subsidiary) peak, the Lax–Filson peak and the Kosugi–Kino peak. A comparison of flow-stress and internal-friction measurements in high-purity refractory body-centered cubic metals confirmed the interpretation of the γ-relaxation in terms of kink-pair generation in a/2<111> screw dislocations. The cores of these dislocations could exist in 2 different configurations, with different slip planes. The {112} configuration was responsible for the γ-relaxation, and the {110} configuration was responsible for the β-relaxation. The existence of 2 distinct core configurations could also account for the difference between reversible and irreversible γ-relaxation in Nb and Ta, and appeared to be the reason for a striking dependence of the α-relaxation upon the deformation temperature. It was proposed that kink-pair formation in non-screw dislocations on {110} planes gave rise to the high-temperature side of the α-relaxation, and that on {112} planes gave rise to the low-temperature side.

Progress and Problems in the Understanding of the Dislocation Relaxation Processes in Metals. A.Seeger: Materials Science and Engineering A, 2004, 370[1-2], 50-66