Investigation of the Melt Flow on Solidified Structure by a Levitation Technique Using Alternative and Static Magnetic Fields

Abstract

A levitation method using the simultaneous imposition of an alternating field and a static magnetic field was applied to study effect of the melt flow on the microstructure of Cu, Cu-1at%Ag alloys, a middle carbon steel alloys and Fe-10at%Ni alloys solidified from the undercooled melt. Convection in the levitated melts was remarkably reduced when the imposed static magnetic field exceeded 1T. Reduction of the melt flow did not affect the nucleation temperature, but caused the morphological transition from the equiaxed grains to the columnar grains for the Cu-Ag, the steel and the Fe-Ni alloys. The experimental results indicated that the melt flow in the mushy region caused the dendrite fragmentation and consequently resulted in formation of the equiaxed grains at the low undercooling region.