PIV study of directional solidification of a binary metal alloy analogue

Abstract

Flows driven by double-diffusive convection during alloy solidification strongly influence the macroscopic solute redistribution, localized remelting and solidification rates which play a dominant role in determining the mechanical, electrical and thermal properties of the final product. This experimental study is carried out to investigate the effect of initial concentration and initial cavity height on the development of double-diffusive convection and on the real-time solidification interface growth during solidification of aqueous sodium chloride solution in a top-cooled rectangular cavity. Aqueous sodium chloride solution is widely used as an analogues model system for most of the alloys to study their solidification behaviour because of its transparency that enables the flow visualization using optical techniques. In the present work, particle image velocimetry (PIV) method is used for the velocity measurement during solidification. PIV measurements show that on increasing the initial concentration and the initial cavity height, the strength of the convection flow increases. The evolution of solidification is also captured using a high-speed (HS) camera. The images captured during solidification indicates that the wavy interface formed due to remelting phenomena caused by double-diffusive convection. Further, we also noticed that the solidification rate decreases by increasing the initial concentration and decreasing the initial cavity height.