With a constant power

frequency and depth of applying vibration

effects of power ultrasonic on nucleation and growth of grain in pure aluminum melt were described by applying ultrasonic at varied temperature ranges with a vibration-transfer tool rod. The results indicate that microstructure of the ultrasonic treated ingot can be significantly refined with average grain size at 77

4

05 μm and increment of isotropic behavior

and the mechanical properties are improved by about 20%. The formation of equiaxed grain is closely dependent on the cavitation effects as a result of creation of amount of nuclei

while microstructure can be greatly refined with the homogeneous distribution of grain by acoustic stream effects as a result of restraining the growth of grain

however

nucleation in the aluminum melt is slightly related to the acoustic stream effects. Microstructure of the pure aluminum can be remarkably refined by cavitation effect combining acoustic stream agitation with increasing in temperature range of applying-vibration. In addition

the action area of power ultrasonic was approached based on solidification structure. It is found that proper applying-temperature is helpful for ultrasonic forming of industrial pure aluminum.