Microstructure of the Ce-modified in situ Mg2Si/Al-Si-Cu composite

The effect of Ce on primary and eutectic Mg2Si phases in in situ Mg2Si/Al-Si-Cu composite is investigated. The results show that, with the increasing of Ce content, the morphology of primary Mg2Si particulate changed from dendritic or irregular to polygonal shape, and its size decreases from ∼100 to ∼15 μm and then increases to ∼30 μm. The eutectic Mg2Si phase changed from flake-like to chrysanthemum-like, and eutectic Si changed to coral-like morphology. Furthermore, a small amount of Ce-rich compounds in the form of Al7Si3.5Cu3.5Ce1 are formed as a result of Ce additions.