With the help of an electromagnetic stirring device

alloy melt quenching and EBSD analysis technology

the microstructure of semi-solid AZ91D magnesium alloy stirred by rotative electromagnetic field with various stirring powers was observed.The results showed that primary α-Mg phase in solidification structure of electromagnetic field stirred AZ91D Mg alloy can be obviously refined to fine rosette-like or spheroidal grains

which are proved to be different grains in three-dimension by EBSD analysis.It was found that the higher the stirring power the finer the primary α-Mg phase

and the less the number of the rosette-like grains

and the more the spheroidal grains.The theoretical analysis indicated that the vigorous flow motion of AZ91D Mg alloy melt ensure more uniformly temperature and solute field as well as larger temperature fluctuation resulting in the formation of the microstructure of semi-solid Mg alloy.