Effect of a high axial magnetic field on the structure of directionally solidified Al–Si alloys

• Published in: Journal of materials research Vol. 30; no. 8; pp. 1043 - 1055
• Main Authors: Du, Dafan, Lu, Zhenyuan, Gagnoud, Annie, Fautrelle, Yves, Ren, Zhongming, Lu, Xionggang, Moreau, Rene, Li, Xi
• Format: Journal Article
• Language: English
• Published: New York, USA Cambridge University Press 28.04.2015; Springer International Publishing; Springer Nature B.V
• Subjects: Alloys; Aluminum alloys; Analysis; Applied and Technical Physics; Biomaterials; Directional solidification; Inorganic Chemistry; Intermetallic compounds; Magnetic fields; Magnetism; Materials Engineering; Materials research; Materials Science; Mechanical properties; Morphology; Nanotechnology; Solids; Studies; Al–Si alloys; high magnetic field; directional solidification; solidification structure
• ISSN: 0884-2914; 2044-5326
• DOI: 10.1557/jmr.2015.55

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 -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.