On low temperature internal friction peaks in deformed metals

The characteristics of the internal friction peaks arising from pinning of dislocations by point defects, and of the Bordoni maxima, are explained without recourse to the concept of kink-formation in terms of small displacements of jogged dislocations, induced by perturbations of the internal stress field. The spectrum of activation energies associated with the Bordoni peak is related to conservative displacements of several types of elementary intersection jogs; the latter present no impediment to dislocation motion at the higher temperatures at which peaks due to point defect pinning of dislocations occur. As the stress perturbations near individual oscillators are uncorrelated, local unpinning can occur at some points without entailing general breakaway of the dislocations.