Sluggish dendrite growth in substantially undercooled liquid Fe-Sb alloy

Dendrite growth within substantially undercooled liquid alloys is usually characterised by a very high growth velocity, even over 100 m/s. Here we report that dendrite growth becomes quite sluggish in a highly undercooled liquid Fe-8.5wt.%Sb alloy because it has a broad solidification temperature range of 412 K. The measured growth velocity of the dendritic -Fe phase increases up to a maximum of only 1.38 m/s at 301 K undercooling. If this liquid alloy is undercooled further by 390 K (0.22TL), the dendrite growth velocity decreases gradually. A structural morphology transition from a coarse dendrite to an equiaxed grain takes place once undercooling exceeds 73 K. Energy dispersive spectroscopy analyses of the solute distribution reveal that solute trapping depends mainly on the actual dendrite growth velocity rather than the degree of undercooling.