The effects of different contents of Sc
addition on the microstructures and properties of the Al 4%Cu alloy were studied
by tensile properties measurement, optical microscope, X ray diffraction analysis, scanning electron microscope (SEM) and energy spectrum analysis. The experimental results show that rare earth element Sc is capable of refining the dendritic structure of the Al 4%Cu alloy, the tensile strength σ b and yield strength σ 0.2 just increase a little when the content of Sc is lower than 0.2%; when the content reaches 0.3%0.4%, σ b and σ 0.2 slightly decrease; but σ b and σ 0.2 rise again when the Sc content is 0.5%, though both of them are lower than those of the Al 4%Cu alloy without Sc
addition. However, Sc addition has little influence on the elongation of the Al 4%Cu alloy. Adding Sc to the Al 4%Cu alloy, when the amount of Sc is lower than 0.2%, Sc mostly exists in the α (Al) solid solution; when the Sc content is in the range of 0.3%0.5%, only a part of Sc exists in the α Al solid solution, the rest appears in two ways: one is that Sc and Al form Al 3Sc which can strengthen the alloy, and the other, Sc interacts with Al and Cu to form AlCuSc phase.