Microstructure-Property Relationships in an Erbium-Modified Al-Si-Mg Alloy

The effects of erbium (Er) addition at various weight percentages (۰-۰.۶ wt.% at an interval of ۰.۲) on the microstructural characteristics, tensile response and wear properties of as-cast Al-۷.۵Si-۰.۵Mg alloy were evaluated. The microstructure of samples was examined by X-ray diffraction, optical microscopy and scanning electron microscopy. The obtained results demonstrated that the incorporation of erbium obviously decreased the α-Al grain size and eutectic Si, and altered the Si morphology from plate to semi-globular. Further addition of erbium (> ۰.۲ wt.%) did not alter the eutectic morphology and size. Moreover, the Al۳Er phase was also observed in the eutectic region after modification. Out of the erbium contents used, ۰.۲ wt.% erbium showed the best influence on the tensile and wear properties. Compared with those of unmodified specimen, the values of ultimate tensile strength and elongation were enhanced by ۳۱% and ۳۹%, respectively with the introduction of ۰.۲ wt.% erbium. Additionally, a remarkable enhancement in the wear properties was observed with the addition of ۰.۲ wt.% erbium.

Keywords:

Al-Si-Mg alloy , Erbium , Eutectic Si , Microstructure , Tensile properties , Wear