Kinetic cross coupling between non-conserved and conserved fields in phase field models

TL;DR

This paper introduces a phase field model incorporating kinetic cross coupling between non-conserved and conserved fields, bridging microscopic simulations with macroscopic descriptions, and discusses implications for solute trapping.

Contribution

It presents a novel phase field model with Onsager kinetic cross coupling and derives its macroscopic reduction, validated by simulations and relevant for solute trapping phenomena.

Findings

Reduced macroscopic model agrees with phase field simulations

Kinetic cross coupling influences solute trapping

Model provides a general framework for alloy transformations

Abstract

We present a phase field model for isothermal transformations of two component alloys that includes Onsager kinetic cross coupling between the non-conserved phase field and the conserved concentration field. We also provide the reduction of the phase field model to the corresponding macroscopic description of the free boundary problem. The reduction is given in a general form. Additionally we use an explicit example of a phase field model and check that the reduced macroscopic description, in the range of its applicability, is in excellent agreement with direct phase field simulations. The relevance of the newly introduced terms to solute trapping is also discussed.