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Li X.,Shanghai University | Fautrelle Y.,SIMAP EPM Madylam G INP CNRS | Gagnoud A.,SIMAP EPM Madylam G INP CNRS | Ren Z.,Shanghai University | Moreau R.,SIMAP EPM Madylam G INP CNRS
Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science | Year: 2016

The influences of high magnetic field (up to 12 T) on the morphology of Pb-Sn and Al-Al2Cu lamellar eutectics during directional solidification were investigated. The experimental results indicate that, along with a decrease in eutectic spacing, the banded structure forms at lower growth speeds under high magnetic field and the band spacing decreases as the magnetic field increases. Moreover, the application of a magnetic field enriches the Cu solute in the liquid ahead of the liquid/solid interface during directional solidification of an Al-Al2Cu eutectic alloy. The effects of high magnetic field on the eutectic points of non-ferromagnetic alloys and the stress acting on the eutectic lamellae during directional solidification have been studied. Both thermodynamic evaluation and DTA measurements reveal that the high magnetic field has a negligible effect on the eutectic points of non-ferromagnetic alloys. However, the high magnetic field caused an increase of the nucleation temperature and undercooling. The numerical results indicate that a considerable stress is produced on the eutectic lamellae during directional solidification under high magnetic field. The formation of a banded structure in a lamellar eutectic during directional solidification under high magnetic field may be attributed to both the buildup of the solute in the liquid ahead of the liquid/solid interface and the stress acting on the eutectic lamellae. © 2016 The Minerals, Metals & Materials Society and ASM International


Du D.,Shanghai University | Lu Z.,Shanghai University | Gagnoud A.,SIMAP EPM Madylam G INP CNRS | Fautrelle Y.,SIMAP EPM Madylam G INP CNRS | And 4 more authors.
Journal of Materials Research | Year: 2015

The effects of an axial high magnetic field on the growth of the α-Al dendrites and the alignment of the iron-intermetallics (β-AlSiFe phases) in directionally solidified Al-7 wt% Si and Al-7 wt% Si-1 wt% Fe alloys were investigated experimentally. The results showed that the application of a high magnetic field changed the α-Al dendrite morphology significantly. Indeed, a high magnetic field caused the deformation of the α-Al dendrites and induced the occurrence of the columnar-to-equiaxed transition (CET). It was also found that a high magnetic field was capable of aligning the β-AlSiFe phases with the <001>-crystal direction along the solidification direction. Further, the Seebeck thermoelectric signal at the liquid/solid interface in the Al-7 wt% Si alloys was measured in situ and the results indicated that the value of the Seebeck signal was of the order of 10 μV. The modification of the α-Al dendrite morphology under the magnetic field should be attributed to the thermoelectric magnetic force acting on the α-Al dendrites. The magnetization force may be responsible for the alignment of the β-AlSiFe phases under the magnetic field. © 2015 Materials Research Society.


Li H.,Shanghai University | Du D.,Shanghai University | Gagnoud A.,SIMAP EPM Madylam G INP CNRS | Fautrelle Y.,SIMAP EPM Madylam G INP CNRS | And 2 more authors.
Journal of Materials Research | Year: 2016

Effect of a transverse magnetic field on macrosegregation and growth of primary Al2Cu dendrites in directionally solidified Al–40 wt% Cu alloys was investigated experimentally. The experimental results indicated that the magnetic field caused the formation of channel-like and freckle segregations. It was also found that the application of the magnetic field benefited the growth of primary Al2Cu dendrites and the axial segregation. Moreover, the magnetic field decreased the primary dendrite spacing and the mushy zone length; however these effects weakened with the increase of the magnetic field intensity. The above experimental results should be attributed to the formation of the thermoelectric magnetic convection during directional solidification under the transverse magnetic field. Copyright © Materials Research Society 2016

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