Effects of ultrasonic treatment on the solidification and mechanical properties of AS31 magnesium alloy were investigated

and its mechanism was described.The results reveal that with the increase of ultrasonic power

the grain size of AS31 magnesium alloy is refined obviously

and the morphology

size and distribution of eutectic Mg

2

Si in the microstructure of the alloy are improved greatly.With the ultrasonic power of 750 W

the eutectic Mg

2

Si phase in the alloy is changed from coarse Chinese script to short rod ones.The average size is reduced from 160μm to 50μm.Meanwhile

the strength and elongation of the alloy reach up to 203 MPa and 3.4%

compared with those of the non-ultrasonic treatment alloy

increased by 25% and 100%

respectively.The fracture analysis of AS31 magnesium alloy without ultrasonic treatment presents cleavage fracture

while the ultrasonic treatment AS31 magnesium alloy presents dimple fracture.