Influence of Erbium Addition on the Microstructural Evolution and Tensile Properties of Al/Mg۲Si in-situ Metal Matrix Composites

This study deals with the effects of erbium (Er) addition on the microstructural evolution and tensile properties of Al-Mg۲Si in-situ metal matrix composites. The morphology of primary Mg۲Si and eutectic phases were observed in details using optical microscope and scanning electron microscopy (SEM). The results showed that the increase of Er content has a slight effect on the size and morphology of primary Mg۲Si phases, but the eutectic structure evolves from the coarse structure into the fine one. Also, with Er addition the eutectic mixtures of Al and Mg۲Si with fibrous morphology has been developed instead of the flake like Al-Mg۲Si eutectic microstructure. Meanwhile, Al۳Er phase was observed in the samples containing Er. The ultimate tensile strength (UTS) of the composite changes under the various content of Er. The maximum strength was found at the ۰.۶ wt% Er with the fine eutectic microstructure. The study of SEM micrographs from the fracture surface of composites revealed that Er addition changes the fracture mode from brittle to ductile one with fine dimples. The mechanism of microstructural evolution was discussed in details.

کلیدواژه ها:

In-situ composites ، Al-Mg۲Si metal matrix composite ، Microstructure ، Tensile properties.