Effect of a high magnetic field on solidification structure in directionally solidified NiAl-Cr(Mo)-Hf eutectic alloy

The effect of a high magnetic field on the microstructure in directionally solidified NiAl-Cr(Mo)-Hf eutectic alloy was investigated experimentally. The obtained results indicated that the application of the magnetic field caused the degeneration of the regular lamellar eutectic structure and induced the columnar-to-equiaxed transition (CET) of eutectic dendrites. In addition, the magnetic field modified the macroscopic solid-liquid interface shape and decreased the volume fraction of the Heusler phase. Furthermore, the amplitude and distribution of the thermoelectric magnetic force (TEMF) and thermoelectric magnetic convection (TEMC) in NiAl-Cr(Mo) eutectic alloy during directional solidification under a high magnetic field were studied by numerical simulation at different scales. It was found that the abovementioned results should be attributed to the coupling effects between the TEMC and TEMF. Besides, present work may provide a new method for modification of eutectic morphology during directional solidification under a high magnetic field.