Supercooling, isothermal soaking and liquid phase separation of Cu-Co alloys

In this paper, liquid phase separation of Cu75Co25 and Cu85Co15 alloys has been investigated during isothermal soaking at different supercooling rates . The results reveal that the Liquid phase separation occurring during isot hermal soaking can develop to a relatively large extent compared with conti nuous rapid cooling, resulting in larger quantities and larger sizes of Co- rich particles. The primary dendrites formed at small supercoolings tend to re-dissolve into the Cu-rich liquid and shrink locally in size leading to dendrites that break into segments. These dendrites and their small segment s can collide with each other under the action of the electromagnetic force during high frequency induction heating and accumulate to form large Go-ri ch particles. It is found that whether the Co-rich droplets from the Liquid separation solidify or not depends on the extent of the liquid phase separ ation at fixed temperature. Once the composition of Go-rich liquid reaches to the miscibility gap borderline, solidification can immediately take plac e. (C) 2001 Elsevier Science B.V. All rights reserved.