Traveling Waves Induced by Sweeping Flows on Solidification Interfaces

TL;DR

This study experimentally demonstrates that controlled sweeping flows induce large-scale traveling waves on solidification interfaces, causing repetitive striations and influencing microstructure development in alloy solidification.

Contribution

It provides the first experimental evidence linking sweeping flows to traveling wave formation on solidification interfaces in alloys.

Findings

Large-scale traveling waves are induced by flow-solidification coupling.

Two distinct traveling wave modes are observed and characterized.

Flow causes downstream microstructure inclination and sidebranch development.

Abstract

Solidification of alloys in a thermal gradient usually involves the generation of flows by thermal or thermosolutal convection. We experimentally study their effects on the dynamics of a solidification interface by inducing a controlled sweeping flow in a directional solidification device. Flow is induced in the sample from an external thermosiphon. Downstream inclination of microstructures and downstream sidebranch development are observed. However, the major outcome is the evidence of large scale travelling waves on the solidification interface. They are induced by the coupling between solidification and flow and yield repetitive striations of the solid phase. Two waves are observed and characterized.