at 563.4◦C for addition of 0.107 wt% Bi, which then increasedto 570.4◦C for 0.187 wt% Bi indicating an unmodified condition.With further Bi additions, no change in the TGwas observed.Microstructural examination clearly revealed that with increasingBi concentration to 0.157 wt%, the Si structure exhibits a partiallymodified morphology (Fig. 9b). With the addition of 0.187 wt% Bi,the Si appears to have lost its modified morphology and exhibitedflake-like structure associated with unmodified alloys (Fig. 9c).