Internal friction sensitivity to precipitation in Al-12 wt% Mg alloy

Abstract In order to improve the understanding of the sensibility of the internal friction phenomena to different stages of precipitation in Al-Mg alloys, the ageing effect of a supersaturated solid solution on the Temperature Dependent Internal Friction (TDIF) spectra has been studied. The research showed that the dissolution of the β phase and the transfer of Mg atoms to a solid solution and the formation of β′ metastable phase have an effect on internal friction. Thus, it was proved that the precipitation or the dissolution of β phase plays an important role in the anelasticity of Al-Mg alloys. A detailed TDIF analysis revealed the sensibility of the internal friction technique to the formation of semi-coherent and non-coherent phases (β′ and β) but it is not sensitive enough to the formation of coherent phases (GP zones). Several observations on the nature and the shape of the precipitates are also discussed.