The effect of Sc addition on the novel nano-AlCu phase in as-cast Al-5%Cu alloy

Abstract

The effects of Sc addition on the primary α-Al phases and novel nano-AlCu phases were investigated in Al-5%Cu alloys without and with 0.8%Sc. The microstructural evolution was characterized by scanning electron microscopy (SEM) and transmission electron microscope (TEM) with energy dispersive X-ray spectroscopy (EDS). In the study, the novel ribbon nano-AlCu phases were found in as-cast Al-5%Cu alloy and the average length is about 200–300 nm. When 0.8%Sc was added into the Al-5%Cu alloy, the α-Al phases were obviously refined from coarse dendrites to fine equiaxed grains and the average grains size decreased to 29.8 μm. Moreover, the number of nano-AlCu phases significantly increases, but the length and width obviously decrease. In addition, the nano-AlCu phases have a good lattice matching relationship with α-Al phases, which can act as a precursor refining α-Al grains.