Macrosegregation is a phenomenon that affects the quality of
industrial castings and therefore attracted many research groups for several
decades. Using magnetic stirring during solidification provides a good
opportunity to control the microstructure of the alloys, thus controlling their
physical properties. However, magnetic stirring is often accompanied by a
change in local concentrations, and new structures form, which could harm the
physical properties This chapter highlights the effect of forced melt flow by a
rotating magnetic field (RMF) on the macrostructure of an Al-Si eutectic alloy.
To serve this purpose, Al-12.6wt% Si alloy samples were solidified in a
vertical Bridgman-type furnace equipped with a rotating magnetic inductor to
induce the flow in the melt. The diameter and length of the sample are 8 mm and
120 mm, respectively. The solidification parameters are; The temperature
gradient (G) of 6 K/m, and the solid/liquid front velocity (v) of 0.1 mm/s.
These samples were divided into parts during the solidification process, where
some of these parts were solidified under the effect of RMF stirring while
others were solidified without stirring.
The structure obtained after solidification showed a
distinct impact of stirring by RMF; new phases have been solidified which are
not originally present in the structure before stirring. Besides the eutectic
structure, the new phases are the primary aluminum and the primary silicon. The
Si concentration and the volume fraction of each phase were measured using EDS
and new image processing techniques. The experimental results reveal that
applying the RMF during the solidification has a distinct effect on the
macrostructure of Al-Si eutectic alloys.
Indeed, the RMF provokes macro-segregation, reduces the
amount of eutectic structure, and changes the sample’s Si concentration
distribution.
Finally, it is concluded that The RMF destroys the coupled
growth of the α-Al and Si eutectic phases at the edges and alters the leading
phase from the Si to the α-Al phase.
Kassab Al-Omari,
Institute of Physical Metallurgy, Metal Forming, and Nanotechnology, University of Miskolc, Hungary.
András Roósz,
Institute of Physical Metallurgy, Metal Forming, and Nanotechnology, University of Miskolc, Hungary and HUN REN- University of Miskolc, Materials Science Research Group, Hungary.
Arnold Rónaföldi,
Institute of Physical Metallurgy, Metal Forming, and Nanotechnology, University of Miskolc, Hungary and HUN REN- University of Miskolc, Materials Science Research Group, Hungary.
Mária Svéda,
HUN REN- University of Miskolc, Materials Science Research Group, Hungary.
Zsolt Veres,
Institute of Physical Metallurgy, Metal Forming, and Nanotechnology, University of Miskolc, Hungary and HUN REN- University of Miskolc, Materials Science Research Group, Hungary.
Please see the link here: https://stm.bookpi.org/EMMSMFMSA/article/view/13082
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