Abstract
This study reports on the phase separation and
solidification behavior of Fe–Cu alloys under microgravity,
utilizing an electrostatic levitation furnace (ELF) aboard the
International Space Station (ISS). Spherical Fe–Cu samples of
varying compositions were first prepared on Earth using an
aerodynamic levitator in an argon atmosphere, then selected
samples were melted and resolidified in space without a
container. Detailed thermal histories were obtained, revealing
distinct cooling plateaus and recalescence events, indicative of
complex solidification dynamics. Microstructural analysis by
electron probe microanalysis showed the formation of a core
shell structure, with Fe-rich phases forming the inner regions and
Cu-rich phases surrounding them, as well as evidence of iron oxide formation likely due to residual
oxygen. The cooling rates and resulting morphologies were found to agree well with phase field
simulations, suggesting that slower cooling in microgravity promotes the development of well-defined
core-shell structures through enhanced droplet movement and mixing. These findings provide new
insights into phase separation and solidification mechanisms in Fe–Cu alloys under microgravity and will
be compared with results from other compositions in future work.
