Coexistence of adjacent vacancy-ordered and eutectic phases in Al–Cu–Ni alloys

Copper-mould-cast Al-Cu-Ni alloys show adjacent coexistence of in situ grown ordered and eutectic phases. A bimodal microstructure of alpha-Al and eutectic alpha-Al+theta-Al2Cu phases with length-scale hierarchy evolves during solidification. Microstructural analysis through Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) shows the presence of Vacancy-ordered phases (VOPs) with different morphologies in two different compositions.