Relaxation Mechanisms in High Purity 99.999 % Aluminium at Medium Temperatures

Abstract. In this work we have studicd the microstructural conditions for the appearance of the P3 relaxation at about 650K in 99.999 % Aluminium. The experimental behaviour of the P3 peak allows us to conclude that it is linked to a process of dislocation mobility. The internal friction (IF) spectra in A1 5N single crystals was studied by Woirgard et al. [1,2] between 300K and 700K and decomposed in a high temperature background plus three relaxation peaks named Pi, P2 and Pg. These relaxations appear also in bicrystals and an annealing at 673K increases the P2 and P3 relaxations. In polycrystals Woirgard et al. [1,2] observe so high the P2 relaxation that the P1 an