Influence of Erbium and Thermal Treatments on the Microstructure and Hardness of Al-Mg-Si Alloy

The influence of Erbium (Er) addition and thermal treatments on the microstructure and hardness of Al-0.5 wt.%Mg-1.0 wt.%Si alloy has been studied. Chemical composition of the alloys was measured by optical emission spectrometry (OES) and x-ray fluorescence (XRF). Microstructural evolution of as-cast, solution-treated, and aged samples were characterized by scanning electron microscope (SEM). The phase identification and elemental distribution were obtained from energy dispersive spectroscopy (EDS). From the microstructure, it was confirmed that solutionization at 570 ͦ C for 15 hours dissolved the Mg 2 Si and Er-rich intermetallics. However, some Fe-rich intermetallics remained after the solution heat treatment. Er addition had a role on the modification of β-AlFeSi and improved the hardness. Er-modified Al-Mg-Si alloy gave a significant improvement in mechanical properties. Therefore, Er is one of the candidate elements that could provide an opportunity for a high-strength Al-Mg-Si alloy.