Effect of Alternating Magnetic Field on Solidification Microstructure of 7050 Aluminium Alloy

The effect of alternating magnetic field frequency on the meniscus,microstructure and element distribution of the static formed ingots of minitype square billet of 7050 aluminium alloy.The results indicate that the meniscus of melt was higher when the frequency of the alternating magnetic field was 777 Hz.The grains were coarse without the alternating magnetic field.There were obvious coarse second-phases in square billets.But the microstructure of square billets was composed of small and symmetrically equiaxed grains with the alternating magnetic field,and they distributed as reticulation.The grains were obviously refined from 171 μm in the absence of the alternating magnetic field to 121-128 μm in the presence of the alternating magnetic field.The elements of the alloy were partly burnt out.The distribution of Mg,Zn,Cu was relatively uniform when the frequency of the alternating magnetic field was 777 Hz.