The effect of Fe content on crystal phase and mechanical properties of 6061 aluminium alloy

Abstract

In order to eliminate the adverse effects of impurity element Fe in aluminium alloy, the effects of Fe content on the microstructures and mechanical properties of 6061 aluminium alloy were studied utilizing scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and tensile testing machine. The results show that Fe exists mainly in α-AlFeSi and β-AlFeSi phases. Elemental Fe promotes the generation of fishbone shaped α-AlFeSi phase, while the percentage of needle shaped β-AlFeSi phase gradually decreases. After homogenizing annealing, the Mg2Si phase has been redissolved, and a large amount of Si element exists in the aluminium matrix. With the increase of Fe and Si content, β→α phase transition has been completed, and the fishbone α-AlFeSi phase accumulates at the grain boundary. After the extrusion forming process, the morphology of the α-Al12(MnFe)3Si phase changes from fishbone to granular, and the bulk deposition of α-Al12(MnFe)3Si improves the strength of 6061 aluminium alloy.