5FeSi相由塊狀轉(zhuǎn)變?yōu)榘雸A形態(tài)。共晶硅和金屬間化合物形態(tài)的演變和細(xì)化主要是由空化效應(yīng)引起的固體破碎、均勻的溶質(zhì)分布、均勻的溫度場及共晶生長時間的縮短造成的。;The effect of ultrasonic vibration (USV) on solidification microstructure of Al-11.5Si-4Cu-2Ni-1Mg-0.45Fe (wt%) piston alloy was investigated. Results show that the significant refinement and morphology transformation from strip into compact polygon can be observed for the primary Si in the alloys produced by USV. The enhanced heterogeneous nucleation and shortened growth time caused by the large undercooling which is triggered by cavitation are responsible for the refinement of primary Si. The morphology of eutectic Si gradually develops from long plate into a short plate structure with increasing the ultrasonic power. Meanwhile, the morphology of α-Al5FeSi phases changes from coarsening block shape to half circle. The morphology evolution and refinement of eutectic Si as well as intermetallic particles are mainly due to the fragmentation of solid crystals, homogeneous solute distribution field and temperature field, and shortened eutectic growth time caused by cavitation."/>