A three-dimensional characterization method for the preferentially oriented precipitation of Ω-phase in stress-aged Al-Cu-Mg-Ag single crystal

It is advantageous and necessary to determine the preferentially oriented behavior of precipitates in three-dimensional space. In this study, the Al-Cu-Mg-Ag single crystal was prepared and the microstructure observation along two <011> zone axes was conducted to build three-dimensional precipitation distribution of the Omega-phase during stress aging. Electron back-scattered diffraction (EBSD) was used to determine the orientation of the single crystal, and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM) was used for the microstructure observation. The results showed that the Omega-phase favors precipitation on the habit planes perpendicular to the loading orientation during compressive stress aging. This study provides a novel method to build three-dimensional precipitation distributions of the precipitates, which is the ideal way to evaluate whether the preferentially orientated precipitation of precipitates has been generated.