Effect of a High Magnetic Field on the Microstructure of Directionally Solidified NiAl-Cr(Mo)-Si Near-Eutectic Alloy at Different Withdrawal Rates

Abstract:

The effect of a 6T high magnetic field on the microstructure of directionally solidified NiAl-Cr (Mo)-Si near-eutectic alloy was investigated at the withdrawal rates of 2, 10 and 50 μm/s. The results showed that the microstructure evolved from planar eutectic to primary NiAl dendrites + cellular eutectic and then to dendritic eutectic with the increasing withdrawal rate. When the magnetic field was imposed, the well-aligned eutectic lamellae were disturbed and transformed into a wavy one at 2 μm/s. When the withdrawal rate increased to 10 μm/s, the application of the magnetic field destroyed the primary NiAl dendrite array and caused the occurrence of columnar-to-equiaxed transition (CET) of the NiAl dendrites. The volume fraction of primary dendrites also decreased. In addition, the width of intercellular/interdendritic regions decreased in cellular/dendritic eutectic structures when directionally solidified under the magnetic field. The above results should be attributed to the combined action of the thermoelectric magnetic force and the thermoelectric magnetic convection.

• Periodical: Materials Science Forum (Volume 898)
• Pages: 407-412
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.898.407
• Online since: June 2017
• Authors: Huan Liu*, Wei Dong Xuan, Xing Fu Ren, Bao Jun Wang, Jian Bo Yu, Zhong Ming Ren
• Keywords: Directional Solidification, High Magnetic Field, Microstructure, NiAl Intermetallics

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