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The evolution of microstructure parameters (precipitate size and volume fraction) for two types of AI-Zn-Mg-Cu alloys (7075 and 7055) during aging has been studied by synchrotron-radiation small angle X-ray scattering (SAXS). The results show that the precipitates are only a few nanometers for both alloys ageing even at higher temperature of 160℃for 72 h (4.44 and 5.82 nm, respectively). The maximum of the precipitate volume fraction increases with in creasing Zn content and is about 0.023-0.028 and 0.052-0.054, respectively. The coarsening of precipitate is consistent with LSW (Lifshitz-Slyozov-Wagner) model even at the initial stage where volume fraction is still varying. The activation energy of coarsening regime has been determined to be about 1.22±0.02 eV and 1.25±0.02 eV for alloys 7075 and 7055, respectively.
The evolution of microstructure parameters (precipitate size and volume fraction) for two types of AI-Zn-Mg-Cu alloys (7075 and 7055) during aging has been studied by synchrotron-radiation small angle X-ray scattering (SAXS). show that the precipitates are only a few nanometers for both alloys aging even at a higher temperature of 160 ° C for 72 h (4.44 and 5.82 nm, respectively). The maximum of the precipitate volume fraction increases with creasing Zn content and is about 0.023- 0.028 and 0.052-0.054, respectively. The coarsening of precipitate is consistent with LSW (Lifshitz-Slyozov-Wagner) model even at the initial stage where volume fraction is still varying. The activation energy of coarsening regime has been determined to be about 1.22 ± 0.02 eV and 1.25 ± 0.02 eV for alloys 7075 and 7055, respectively.