Nucleation and phase selection in undercooled Fe-Co melt

In order to investigate phase selection between stable and metastable phases upon rapid solidification of Fe₇₀Co₃₀ single-phase alloy, different undercooling experiments were performed. The critical undercooling for forming metastable phase upon spontaneous crystallization was observed as ∼203 K, whereas, it decreased to ∼169 K if artificially triggering was adopted. This can be ascribed to a substantial reduction of the catalytic potency factor f(θ) of bcc phase in the case of triggered nucleation.