Microstructural formation of semi-solid AZ91D alloy stirred by electromagnetic field

Weimin Mao, Zisheng Zhen, Hongtao Chen, and Xueyou Zhong Materials Science and Engineering School, University of Science and Technology Beijing, Beijing 100083, China

摘 要：<正>With the help of an electromagnetic stirring device, alloy melt quenching and EBSD （electron back scatter diffraction） analysis technology, the microstructure of the semi-solid AZ91D magnesium alloy slurry stirred by rotational electromagnetic field under different stirring power conditions has been studied. The results show that the size of primary a-Mg phase is reduced obviously when the solidifying alloy melt is stirred by rotational electromagnetic field, moreover, the primary a-Mg grains are changed to fine rosette grains or spherical grains which are proved to belong to the different grains in three-dimension by the EBSD analysis technology. The results also show that the stirring power is an important processing parameter in the preparation of the semi-solid AZ91D magnesium alloy slurry. The larger the stirring power, the finer the primary a-Mg grains, the less the rosette primary a-Mg grains, and the more the spherical primary a-Mg grains. Theoretical analysis indicates that a stronger flow motion leads to a more even temperature field and solute field and a stronger man-made temperature fluctuation in the alloy melt so that the specially fine rosette and/or spherical primary a-Mg grains are formed in the semi-solid AZ91D magnesium alloy slurry.

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