Internal friction and elastic modulus were measured as function of temperature, strain amplitude and frequency in Al–Mg solid solutions by means of free-decay and forced oscillation torsion pendula. Samples with 4at%Mg were used. The internal friction spectrum, at 100 to 550K, was found to be composed mainly of a low-temperature background between 100 and 400K, which did not depend on temperature, but depended markedly upon the strain amplitude in the range of 5 x 10−6 to 10−4 and of an internal friction peak (at about 440K for 1Hz), which evolves into a rapidly rising background at higher temperature. The mechanical spectroscopy results were analyzed in terms of a solute-dislocation interaction model with variation of the average length of dislocation segments. Furthermore, the activation energies of the peak and high temperature background were found to be close to the activation energy of diffusion of Mg solute atoms in Al. As a consequence, both components could be interpreted by the high temperature dragging of Mg solute atoms by the dislocations.

Study of Solute Atom-Dislocation Interactions in Al–Mg Alloys by Mechanical Spectroscopy. M.Atodiresei, G.Gremaud, R.Schaller: Materials Science and Engineering A, 2006, 442[1-2], 160-4