Influence of minor La addition on the solidification, aging behaviors and the tensile properties of Al-Mg-Si alloys

The influence of rare earth on the microstructures as well as properties of Al and its alloys has attracted great attention recently. However, contradictory results always were reported, some previous studies found that rare earth promoted the increment of the tensile properties of Al alloy, some other researchers though rare earth had no significant effect on the tensile properties or decreased the tensile properties. In the present work, the effects of minor rare earth element La on the solidification, aging behaviors and the tensile properties of Al-Mg-Si alloys have investigated by thermal analysis, microstructural characterizations and properties tests. The results demonstrate that the ultimate tensile strength and yield strength of Al-Mg-Si alloy can be increased by adding minor rare earth La. The effect mechanism of La has also been explored, it indicates that minor La enhances the strength of the Al-Mg-Si alloy by decreasing grain size and promoting the precipitation of (Mg, Si) phase. This study provides a way for manufacturing Al-Mg-Si alloys with excellent mechanical properties.