Correlated process of phase separation and microstructure evolution of ternary Co-Cu-Pb alloy

Abstract

The phase separation and rapid solidification of liquid ternary Co45Cu42Pb13 immiscible alloy have been investigated under both bulk undercooling and containerless processing conditions. The undercooled bulk alloy is solidified as a vertical two-layer structure, whereas the containerlessly solidified alloy droplet is characterized by core-shell structures. The dendritic growth velocity of primary α(Co) phase shows a power-law relation to undercooling and achieves a maximum of 1.52 m/s at the undercooling of 112 K. The Pb content is always enriched in Cu-rich zone and depleted in Co-rich zone. Numerical analyses indicate that the Stokes motion, solutal Marangoni convection, thermal Marangoni convection, and interfacial energy play the main roles in the correlated process of macrosegregation evolution and microstructure formation.