Abstract: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 strengthσband yield strengthσ0.2just increase a little when the content of Sc is lower than 0.2%; when the content reaches 0.3% 0.4%,σbandσ0.2slightly decrease; butσband σ0.2rise 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 theα(Al) solid solution; when the Sc content is in the range of 0.3% 0.5%, only a part of Sc exists in theα-Al solid solution, the rest appears in two ways: one is that Sc and Al form Al3Sc which can strengthen the alloy, and the other, Sc interacts with Al and Cu to form AlCuSc phase.

Key words: Sc; Al-Cu alloy; microstructure; mechanical properties