The mechanical vibration was applied on the AZ91 Dmagnesium alloy prepared by the expendable pattern shell casting

and effects of pouring temperature

vibration frequency and amplitude on microstructure of AZ91 D magnesium alloy prepared were investigated.The results show that the dendritic structure is reduced significantly by the mechanical vibration

and microstructure of AZ91 D magnesium alloy is refined with decreasing in the pouring temperatures

however

over-low pouring temperature is weaken to mechanical vibration to play the best effect

and a favourable microstructure of AZ91 D magnesium alloy can be observed at 730 ℃

and grains exhibit equiaxed structure.With the increase of vibration frequency

the microstructure of AZ91 D magnesium alloy is refined gradually.When the vibration frequency is 100 Hz

grain size of the primaryαphase is only 166.4μm

and theβphase is distributed in form of fine granular shape.The microstructure of AZ91 D magnesium alloy can be refined with the decrease of the vibration amplitude.When the amplitude is 1.0mm

the fine and spherical grain can be prepared.