During the cooling process of an Al-Bi monotectic alloy melt, the homogeneous liquid phase transforms into two immiscible liquid phases. Under conventional gravity casting conditions, a solidification microstructure with severe macroscopic segregation easily forms in Al-Bi monotectic alloys, which limits their industrial application. Therefore, it is necessary to effectively control the solidification microstructure (refinement and homogenization) of Al-Bi monotectic alloys. In recent years, researchers have conducted extensive studies on how to improve or avoid the segregation microstructure of Al-Bi and other monotectic alloys, such as rapid solidification, the application of external fields and the addition of third elements. Among them, the addition of third elements is most likely to achieve low-cost and scalable preparation of Al-Bi based monotectic alloys with fine and uniform microstructures. In this regard, this paper mainly reviews the research progress on the addition of third elements, such as alloying elements, Al-(Ti)-(B) systems and ceramic particles, to Al-Bi based monotectic alloys. It can be concluded that the third element containing ceramic particles can effectively refine and homogenize the Bi rich phase in the Al-Bi based alloy. This related research is highly important for

achieving large-scale industrial applications of Al-Bi based monotectic alloys.