Dendrite fragmentation: an experiment-driven simulation

T Cool; P W Voorhees

doi:10.1098/rsta.2017.0213

Dendrite fragmentation: an experiment-driven simulation

Philos Trans A Math Phys Eng Sci. 2018 Feb 28;376(2113):20170213. doi: 10.1098/rsta.2017.0213.

Authors

T Cool¹, P W Voorhees²

Affiliations

¹ Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA.
² Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA p-voorhees@northwestern.edu.

Abstract

The processes leading to the fragmentation of secondary dendrite arms are studied using a three-dimensional Sn dendritic structure that was measured experimentally as an initial condition in a phase-field simulation. The phase-field model replicates the kinetics of the coarsening process seen experimentally. Consistent with the experiment, the simulations of the Sn-rich dendrite show that secondary dendrite arm coalescence is prevalent and that fragmentation is not. The lack of fragmentation is due to the non-axisymmetric morphology and comparatively small spacing of the dendrite arms. A model for the coalescence process is proposed, and, consistent with the model, the radius of the contact region following coalescence increases as t^1/3 We find that small changes in the width and spacing of the dendrite arms can lead to a very different fragmentation-dominated coarsening process. Thus, the alloy system and growth conditions of the dendrite can have a major impact on the fragmentation process.This article is part of the theme issue 'From atomistic interfaces to dendritic patterns'.

Keywords: dendrite; fragmentation; phase-field simulation.