Modelling of Secondary Dendrite Arms Evolution during Solidification by a Phase-field Method

Qi-Wei Zheng,Tao Jing,Hong-Biao Dong

doi:10.1016/j.matpr.2015.05.063

Qi-Wei Zheng, Tao Jing + Show 1 more

Open Access

https://doi.org/10.1016/j.matpr.2015.05.063

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Abstract

Mechanical property of cast metals is strongly dependent on solidification structure, in particular the secondary dendrite arms spacing. In this study a Phase Field Method was used to simulate the evolution of dendritic structure with coupled heat and solute diffusion during solidification. Coarsening and remelting of the secondary arms were simulated. It is found that (1) the base of the secondary arms doesn’t decrease as coarsening theory predicts and the arms spacing keeps unchanged when the arm grows into a steady state, but the volume of the arms increases; (2) both remelting of secondary arms and coarsening of secondary arms can be observed, which agrees with the coarsening theory and experiment observations.

Highlights

Mechanical property of cast metals is strongly dependent on solidification structure, in particular the secondary dendrite arms spacing[1,2,3]
In this study a Phase Field Method was used to simulate the evolution of dendritic structure with coupled heat and solute diffusion during solidification
The phase-field model we used in our paper is based on the model proposed by Karma[5], in which both heat and solute diffusion are considered, so this method was applied to study the solute distribution in the solidification of a binary alloy in different thermal condition

Summary

Introduction

Mechanical property of cast metals is strongly dependent on solidification structure, in particular the secondary dendrite arms spacing[1,2,3]. Many experimental investigations have revealed that the smaller the secondary arm spacing, the higher the strength of the as-cast metals[4]. Many efforts have been focused on the. Qi-Wei Zheng et al / Materials Today: Proceedings 2S (2015) S466 – S473 mechanism of the secondary aim spacing during solidification, there is no convincing mechanism to explain the spacing. In this study a Phase Field Method was used to simulate the evolution of dendritic structure with coupled heat and solute diffusion during solidification. Mechanism for spacing, including coarsening and remelting of the secondary arms will be reported

Description of Phase Field Model

Simulation and Results

Remelting of secondary arms

Coarsening of secondary arms

Conclusion