2018 Volume 58 Issue 5 Pages 899-904
The effect of a steady magnetic field (SMF) on microsegregation in the Al-4.5mass%Cu alloy during equiaxed solidification was investigated experimentally. It was found that the amount of microsegregation increased with increasing the SMF intensity at the same cooling rate. The variation of the microsegregation level with the SMF intensity at different cooling rates showed the consistent tendency. The effect of the change in various factors such as diffusivity in the solid phase, dendrite coarsening and undercooling on the microsegregation behavior was analyzed. The reduction of diffusivity in the solid phase in the SMF increased the microsegregation level. The increase in average nucleation undercooling of primary Al phase in the SMF, which was examined by the differential thermal analysis (DTA), led to decrease the amount of microsegregation. The enhancement of coarsening kinetics in the SMF increased the microsegregation level. Under the combined action of various factors, it was found that the increase in microsegregation in the range of the cooling rates under investigation was mainly attributed to the increase of the secondary dendrite arm spacing (SDAS) and the decrease in solid diffusion coefficient induced by the SMF.
