利用挤压铸造制备Ａｌ２Ｏ３／Ａｌ－Ｓｉ合金复合材料，在扫描电子显微镜（ＳＥＭ）上观察了复合材料中的硅相形貌．结果表明Ａｌ２Ｏ３纤维与Ｓｉ相之间存在共格界面，可作为硅相非自发形核的衬底；复合材料中的初生硅可在纤维表面形核生长为颗粒状；复合材料中的纤维在Ａｌ－Ｓｉ共晶体的共生生长过程中，可触发孪晶，导致纤维附近的共晶硅里变质形态． Al2O3 / Al-Si alloy composites were prepared by extrusion casting. The morphology of the silicon phase in the composites was observed by scanning electron microscopy (SEM). The results show that there is a coherent interface between the Al2O3 fiber and the Si phase, which can be used as a substrate for the non-spontaneous nucleation of the silicon phase. The primary silicon in the composite material can nucleate and grow into a granular form on the fiber surface. -Si eutectic symbiosis growth process, can trigger twins, resulting in fiber near the eutectic silicon in the metamorphic state.