Dendritic growth kinetics of undercooled Fe-B alloy melts
2014
In metallic alloys dendritic growth is the major crystal growth mode
controlling the evolution of the microstructure during solidi�cation.
The present work investigates the growth kinetics on pure Fe and Fe-
B alloy melts in order to verify models for dendritic growth in undercooled
melts. In detail, we analyze the e�ect of solute redistribution
and solute trapping on the rapid growth of dilute Fe-1 at.% B alloy
with B showing a small partitioning coe�cient. For in-situ studies on
deeply undercooled melts electromagnetic levitation technique (EML)
is used. The rapid solidi�cation is recorded by a high-speed camera.
Undercoolings from 50 K to 300 K prior to solidi�cation leads to growth
velocities of several cm/s up to m/s. Concerning terrestrial EML the
electromagnetic �eld necessary for levitation induces strong convective
uid
ow inside the melt. To investigate the e�ect of convection on the
growth kinetics experiments on parabolic
ight are carried out under
reduced gravity conditions. The microstructure of the solidi�ed sample
is analyzed by SEM and EBSD. Experimental results will be presented
and discussed in the frame of current models for dendritic growth in
undercooled melts. This research work is supported by DFG contract
HE1601/18 and by ESA under contract 4200020277 and 4200014980.
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