Mechanical spectroscopy of Al-Mg alloys

The internal friction of deformed, annealed, and quenched Al-Mg alloys with Mg contents of 0-12 wt % has been studied as a function of temperature. The measurements have been performed in the range of 25-580A degrees C at 0.3-30 Hz using a DMA Q800 TA Instruments dynamic mechanical analyzer at the maximum amplitude of deformation E >(0) = 5 x 10(-5). In annealed alloys with Mg contents up to 5 %, a relaxation IF peak with activation parameters (activation energy H a parts per thousand 1.7-2.1 eV) has been detected. In alloys with 8-12% Mg, this relaxation peak is absent and, at a lower temperature, another IF peak appears (with an activation energy H of about 1 eV), which is interpreted as the Zener peak in terms of the combination of activation parameters. The article discusses the nature of these peaks and the influence of alloying on the relaxation mechanisms. In cold-worked alloys, an IF pseudo-peak takes place, which is related to the recrystallization of samples, and its temperature position in the alloys that contain more than 5% Mg depends not only on the degree of deformation, but also on the dissolution temperature of the beta phase.