摘要
Al 5083 alloys(5.25 at.% Mg) of different tempers(H131 and H116) were aged at low temperatures(50and 70?C) for 41 months. Scanning transmission electron microscopy(STEM), energy-dispersive X-ray spectroscopy(EDS), and atom probe tomography(APT) were applied to characterize precipitates formed in the sensitized samples. Experimental results revealed that the size of Mg-rich precipitates increased with aging time at 70?C for both alloys. APT results showed that Mg-rich precipitates of different Mg concentrations and morphologies formed in Al matrix and on the interface of Al matrix/pre-existing particles. In addition, a model based on local equilibrium of chemical potential and multi-class precipitates number evolution was adopted to predict the multiphase precipitation process in the Al-Mg binary system. The overall trend of precipitate radius and number density predicted by the model matched well with the experimental results. Moreover, modeling results revealed that nucleation and coarsening occurred faster in Al 5083 H131 than in Al 5083 H116 when aged at same temperature. The high density of dislocations and the pipe diffusion mechanism of dislocations can be used to explain such behavior.
Al 5083 alloys(5.25 at.% Mg) of different tempers(H131 and H116) were aged at low temperatures(50and 70?C) for 41 months. Scanning transmission electron microscopy(STEM), energy-dispersive X-ray spectroscopy(EDS), and atom probe tomography(APT) were applied to characterize precipitates formed in the sensitized samples. Experimental results revealed that the size of Mg-rich precipitates increased with aging time at 70?C for both alloys. APT results showed that Mg-rich precipitates of different Mg concentrations and morphologies formed in Al matrix and on the interface of Al matrix/pre-existing particles. In addition, a model based on local equilibrium of chemical potential and multi-class precipitates number evolution was adopted to predict the multiphase precipitation process in the Al-Mg binary system. The overall trend of precipitate radius and number density predicted by the model matched well with the experimental results. Moreover, modeling results revealed that nucleation and coarsening occurred faster in Al 5083 H131 than in Al 5083 H116 when aged at same temperature. The high density of dislocations and the pipe diffusion mechanism of dislocations can be used to explain such behavior.
基金
supported by Office of Naval Research, Award Number: N000141210507
the Oak Ridge National Laboratory’s High Flux Isotope Reactor, which is sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy
University of Utah USTAR shared facilities support, in part, by the MRSEC Program of NSF under Award No. DMR-1121252
