Effects of minor Zr and Er on microstructure and mechanical properties of pure aluminum

Effects of minor Zr and Er on microstructure and mechanical properties of pure aluminum have been investigated using optical microscopy, electron microscopy, X-ray diffraction and MTS tester. It has been found that addition of 0.2 wt% Zr can refines the grain size of the as-cast alloy due to the formation of primary Al3Zr. However, addition of 0.2 wt% Er only can refine dendritic structure. The addition of Er to pure aluminum can change the morphology and size of Fe-phase of aluminum alloys. The solid solution decomposes to form nanosized secondary Al3Zr, Al3Er and Al3(Zr, Er) precipitates during ageing process. These precipitates can improve strength and the recrystallization resistance. By addition of both Zr and Er to pure aluminum, it can improve the mechanical properties, which is superior to that of pure aluminum, significantly.