Microstructure Evolution of A356 Alloy Under Modification by Antimony

Abstract

The effects of antimony (Sb) addition on the microstructure properties of Solidified A356 alloy were investigated. A356–X wt. %Sb (X = 0, 0.1, 0.2 and 0.3) alloys were fabricated using by the permanent mold process. Two different approaches to modification by solidification process have been pursued physically induced and chemically stimulated. The physical relies mainly on the use of external field, such as ultrasonic vibration, while the chemical rout depends primarily on addition of element, which is the subject of this research work. Antimony was used to modify the microstructure of A356 alloy. The effect of addition level of antimony on the solidification of the A356 alloy was investigated and the obtained samples were characterized by optical microscopy, scanning electron microscopy (SEM) and EDS X-ray analysis (EDS). The results showed that: 1)both the dendritic α-Al solid solution and eutectic silicon were significantly modified; 2) the dendritic primary aluminium became globular, and the plate-like or big spherical eutectic silicon turned into fibrous shape and small spheres during the solidification process. The mechanism of the microstructure evolution under inoculated by Sb element was also preliminarily discussed.