Investigation of defect dynamics in Al-Si-Mg polycrystals by simultaneous measurements of internal friction and acoustoplastic effect

摘要

Dynamics of structural defects was investigated in situ during quasistatic deformation of polycrystalline Al-1wt.%Si-0.3wt.%Mg and Al-12wt.%Si-0.3wt.%Mg alloys by means of simultaneous measurements of internal friction and acoustoplastic effect. The alloys were subjected to different heat treatments after quenching: natural ageing at room temperature (T4 treatment) and peak ageing at 433 K for 8 hrs (T6 treatment). This enabled us to study the effect of different microstructure components - solute clusters (for the T4 treatment), GP zones and β″ precipitates (for the T6 treatment), coarse Si particles (for Al-12wt.%Si-0.3wt.%Mg) - on the irreversible and reversible components of dislocation motion under the combined action of oscillatory and quasistatic stress. Based on the data obtained, conclusions have been drawn about microstructural mechanisms of the acoustoplastic effect.