Microstructure evolution of A356 alloy under compound field

Compound field (combination of power ultrasonic field and rotating electromagnetic field) was used to modify the microstructure of A356 alloy. The effect of compound field on the solidification of the A356 alloy was investigated and the obtained samples were characterized by optical microscopy and scanning electron microscopy (SEM). The results showed that: (1) both the primary aluminum and eutectic silicon were significantly refined; (2) the dendritic primary aluminum became spherical, and the plate-like eutectic silicon turned into rod-like during the solidification process under compound field. The mechanism of the microstructure evolution under compound field was also preliminarily discussed. (C) 2009 Elsevier B.V. All rights reserved.