The origin of nuclei and the refinement mechanism for solidified superalloy IN718 under pulsed magnetic field

The grain refinement effect of a pulsed magnetic field on superalloy IN718 was investigated. The experimental results show that fine equiaxed grains are acquired under the pulsed magnetic field. The refinement effect of the pulsed magnetic field is affected by the mold temperature. And the mixed grains are found in the solidified microstructures under the pulsed magnetic field. The origin of nuclei under the pulsed magnetic field is from the mold wall because of the rough mold surface, the undercooling, and the melt vibration, which all contribute to the refinement of solidified grains.