Effect of longitudinal magnetic field on the microstructure of directionally solidified superalloy DZ417G with different sizes

Abstract

In order to understand the influence of a longitudinal magnetic field on the microstructures of the superalloy DZ417G with different sample sizes, the superalloy DZ417G was directionally solidified under a longitudinal magnetic field. The solidification structures of the alloy with various dimensions of specimen have been investigated. The results showed that the columnar dendrites on the edge of samples were broken and changed into equiaxed dendrites in the magnetic field at the withdrawal velocity of 5 μm/s and temperature gradient of 70°C/cm. Additionally, it was found that equiaxed dendrites area expanded from the edge to the center of sample and the number of freckle-like macrosegregation increased with the size of sample. The columnar to equiaxed transition and freckle-like macrosegregation can be attributed to the thermoelectric magnetic convection (TEMC) induced by the magnetic field in the front of solid/liquid interface during directional solidification. © Right.