The effects of the minority phase on phase separation in Fe–Sn hypermonotectic alloy

Fe–Sn hypermonotectic alloys were solidified by induction heating method and melt spinning technique, and the effects of the minority phases (phase with small volume fraction) on the morphology evolution and phase separation are investigated. Under conventional cooling condition in bulk sample, the layered structure can form when the minority phase is Sn-rich, however, macrosegregation occurs when the minority phase is Fe-rich. Under melt-spun condition, the migrating trace of the Sn-rich globules was captured in the Fe–40at%Sn and Fe–47at%Sn alloy ribbons. The Fe-rich particles maintained near-perfect spherical shape in the Fe–60at%Sn alloy ribbons. The competition of the Manrangoni migration and the different direction Stokes motions of different MP phases is responsible for the layered and macro-segregation microstructure formation when Sn-rich and Fe-rich phase are MPs, respectively. This is confirmed by the microstructure captured in the initial stage under high cooling rate condition during melting spinning process. The results might provide an in-depth insight into the contribution of minority phase on the phase separation process and be helpful to control the microstructure formation under different solidification conditions.

► Different minority phases have different effects on the phase separation process.
► Competition between Mirangoni convection and Stokes motion of MP plays a key role.
► Solidification characteristics at initial stage of phase separation are captured.