ZL201 aluminum alloy semi-solid slurry was prepared by indirect ultrasonic vibration method（IUV）

in which the horn is vibrated under the outside of the metallic cup with alloy melt. Effects of IUV temperature and time on microstructure of the semi-solid slurry as well as primary grain distribution in the slurry under ultrasonic vibration condition were observed was investigated. The results show that after applying the IUV for approximately 60 s on the melt near or above the liquidus temperature

semi-solid slurry with grain shape coefficient of 0.55 and average grain diameter of 70 μm can be prepared. During IUV time within 60 s

grain shape coefficient and average grain diameter are increased with increasing in vibrating time

while the IUV time more than 60 s

shape coefficient is decreased to some extent. The grain distribution in the whole cup is uniform

and the average grain diameter of the top and the bottom is slightly bigger than that in the middle. A large quantity of free grain is observed near the cup wall within 1 to 3 mm to the edge

which indicates that the IUV has high-frequency mechanical vibration effects.