In-situ experimental investigations of the morphological characteristics of plumes and chimneys formed during the directional solidification of a binary alloy

Abstract The defects such as freckles formed during the directional solidification of binary alloys severely affect performance cast products. phenomenon freckle formation is strongly influenced by convective flows generated solidification. rejection solute at solid/liquid interface induces concentration gradients in liquid. These combination with existing temperature gradients, may induce buoyancy-driven convection mushy zone (plumes) and parent liquid region (fingers). As evolves, small chimneys are formed, which leads to discrete plumes interdendritic have a very complex flow structure structural compositional heterogeneities final product. current study an effort investigate morphological characteristics alloy For this, controlled experiments bottom-cooled rectangular cavity analogue transparent aqua ammonia system (NH 4 Cl + 74 wt% H 2 O) performed. Particle Image Velocimetry (PIV), High Speed (HS) imaging thermocouples measurement techniques used for real-time field, solidified dynamics local course dynamical nature captured morphology (shape, size, spacings, etc.) (velocity magnitude, shape, quantified. phase-locking 180° phase difference due coupling between nearby observed. Also, evolution double-diffusive layers (DDLs) critical value thermal Rayleigh number onset DDLs estimated.