The microstructure and tensile property of the hypoeutectic Al-Si alloy with and without microalloying of Sc and Zr were studied by means of the optical microscope (OM), Transmission electron microscopy (TEM) and the tensile test. The focus of this work is the effect of microalloying and tensile deformation on the internal structure (i.e. nanoscale precipitates and the stacking faults) in eutectic Si phase. The results show that the nanoscale precipitates are evident in eutectic Si phase in Al-Si alloy without any special heat treatment or modification. The additions of Sc and Zr into the Al-Si alloy increased the size of the nano precipitates, and significantly promoted the formation of the stacking faults inside the eutectic Si phase. Moreover, the eutectic Si phase experienced twinning deformation during the tensile deformation of the Al-Si based alloy, and this twinning deformation was more pronounced with increasing the tensile strength of the Al-Si based alloy. It is proposed that the deformation of the eutectic Si phase also contributed to the property and the ductility of the Al-Si based alloy.

通过光学显微镜（OM），透射电子显微镜（TEM）和拉伸试验研究了具有和不具有Sc和Zr微合金化的亚共晶Al-Si合金的组织和拉伸性能。这项工作的重点是微合金化和拉伸变形对共晶Si相内部结构（即纳米级析出物和堆垛层错）的影响。结果表明，在不进行任何特殊热处理或改性的情况下，Al-Si合金的共晶Si相中明显存在纳米级析出物。在Al-Si合金中添加Sc和Zr会增加纳米析出物的尺寸，并显着促进了共晶Si相内部堆垛层错的形成。此外，共晶Si相在Al-Si基合金的拉伸变形过程中经历孪生变形，并且该孪生变形随着Al-Si基合金的拉伸强度的增加而更加明显。提出共晶Si相的变形也有助于Al-Si基合金的性能和延展性。