We have developed two sets of power ultrasonic double vibrating head equipment to prepare semi-solid A356 alloy slurry.Effects of different arrangement way of the double vibrating heads with power of 1 000 and 1 500 W

such as transducer arrangement flow channel and the opposite direction arrangement flow channel apparatus

on microstructure of semi-solid A356 alloy were analyzed.The solidification mechanism of the alloy under ultrasonic power field was approached in a state of movement

and effects of mechanical effects

thermal effects and acoustic stream effects on grain size in the semi-solid A356 alloy were presented.The results show that the refinement and spheroidization of microstructure in the alloy treated is closely related to the arrangement of the vibrating head

where transducer arrangement flow channel is superior to the opposite direction.Microstructure of the alloy on the flow channel exhibits finer as a result of chilling effects and vibration effects during solidification process.The grain become coarse outside flow channel

and the grain is spheroidized due to the co-action of inclined flow channel and ultrasonic.