Enhanced mechanical properties of hypoeutectic Al-10Mg2Si cast alloys by Bi addition

In the present work, the influence of Bi on the microstructures, tensile properties, and fracture behavior of the cast Al-10Mg2Si alloys has been systematically investigated. It was found that Bi addition caused a significant modification and refinement efficiency on the eutectic Mg2Si in the cast Al-10Mg2Si alloys. The morphology of the eutectic Mg2Si in the cast alloys transformed from plate-like structure to a thin coral-like and fibrous one, and the mean size and aspect ratio sharply decreased with the increase of Bi content. Bi addition changed the mode of fracture from brittle to ductile due to the presence of a large number of deep and well-distributed dimples, and fine Mg2Si particles embedded in the Al-matrix, resulting in the significant improvement of the tensile properties of the cast Al-10Mg2Si alloys.