A new internal friction peak has been observed around 125°C (| = 1 Hz) in AlMg specimens twisted and subsequently annealed at an elevated temperature. This peak appears only when internal friction measurements are taken at descending temperatures. It does not appear in the case of tensile deformation and the peak is suppressed by subsequent tensile deformation. The activation energy is found to be 0.7 ± 0.1 eV and τ0 is 10-8 s. The peak is very sensitive to application of a small bias-stress. It is assumed that the mechanism of this peak is the stress-induced re-orientation of an <100 > split interstitials or dumbbell of MgMg atoms enhanced by the stress field of moving dislocation kinks in aluminium.
|Number of pages||7|
|Journal||Acta Metallurgica et Materialia|
|State||Published - May 1991|