Relation Between Bulk and Interface Descriptions of Alloy Solidification

TL;DR

This paper establishes a connection between bulk and interface models of alloy solidification, deriving exact interface expressions and revealing a symmetry that affects Onsager coefficients, especially at low velocities.

Contribution

It introduces a novel derivation linking bulk and interface descriptions for alloy solidification, including exact flux-force relations and symmetry analysis.

Findings

Exact expressions for fluxes and forces at the interface

Discovery of a continuous symmetry at low velocities

Identification of negative friction coefficients in crystallization

Abstract

From a simple bulk model for the one-dimensional steady-state solidification of a dilute binary alloy we derive an interface description, allowing arbitrary values of the growth velocity. Our derivation leads to exact expressions for the fluxes and forces at the interface and for the set of Onsager coefficients. We, moreover, discover a continuous symmetry, which appears in the low-velocity regime, and there deletes the Onsager sign and symmetry properties. An example is the generation of the sometimes negative friction coefficient in the crystallization flux-force relation.