Beijing Univ Aeronaut & Astronaut, Sch Mat Sci & Engn, Beijing 100083, Peoples R China
; Chinese Acad Sci, Inst High Energy Phys, Beijing Synchrotron Radiat Lab, Beijing 100039, Peoples R China
The evolution of microstructural parameters (mean size and volume fraction) of precipitates in three types of Al-Zn-Mg-Cu alloys during ageing has been studied by synchrotron-radiation small angle x-ray scattering (SAXS). The influence of Zn content on the precipitation has been analyzed. The results show that the precipitates are in nanometer scale for the three types alloys (A, B, C). The maxima of the precipitate volume fractions for A, B and C increase with Zn content and are about 0.023-0.028, 0.052-0.054 and 0.04 respectively. The evolution of volume fraction at a certain temperature is consistent with the kinetic process of precipitate nucleation, growth and Ostwald ripening.