Making slurry with fine and spherical solid particles is one of the most important issues in semi-solid process. In this study, we tried to make slurry by applying mechanical vibration, and investigated the effects of the factors of vibration on the size and shape of solid particles. The slurry was prepared by pouring molten AC4CH aluminum alloy into a vibrating metal container, and the vibration conditions of the container were controlled. As a result, the solid particles in the slurry became fine and spherical with increasing acceleration amplitude at the same frequency, or with decreasing frequency and same acceleration amplitude. On the other hand, at the same velocity amplitude and different frequency and acceleration amplitude, the solid particles became dendritic shape with high or low frequency. The solid particles were most fine and spherical at the frequency of 50Hz. The results of calculating the particle diameter and particle roundness showed that the solid particles became fine and spherical with increasing velocity amplitude. Additionally, the shapes of the solid particles were affected by frequency and displacement amplitude. The solid particles in the slurry became fine and spherical with the application of mechanical vibration higher than a certain frequency and displacement amplitude level. Furthermore slurry with sufficient fine and spherical particles could be obtained by applying mechanical vibration with frequency of 50Hz and acceleration amplitude higher than 49.0m/s2.
