Interface Faceting-Defaceting Mediated by Disconnections

TL;DR

This paper reveals how elastic interactions between disconnections at crystalline interfaces induce a first-order thermodynamic transition, significantly affecting interface morphology and kinetics, supported by numerical simulations.

Contribution

It introduces a continuum disconnection-based model showing elastic interactions cause a faceting-defaceting transition in interfaces, aligning with experimental observations.

Findings

Elastic interactions lead to a first-order transition.

Interface morphologies are strongly modified by disconnection interactions.

Numerical simulations confirm the impact on interface kinetics and shapes.

Abstract

An intrinsic feature of nearly all internal interfaces in crystalline systems (homo- and hetero-phase) is the presence of disconnections (topological line defects constrained to the interface that have both step and dislocation character). Disconnections play a major role in determining interface thermodynamics and kinetics. We demonstrate that elastic interactions between disconnections lead to a thermodynamic, first-order, finite-temperature, faceting-defaceting transition, in agreement with experiments. These elastic interactions strongly modify equilibrium interface morphologies (compared with those solely determined by anisotropic surface energy) as well as the kinetics and morphologies of migrating interfaces. We demonstrate these phenomena through numerical simulations based upon a general, continuum disconnection-based model for interface thermodynamics and kinetics applied to embedded particles/grains, steady-state interface migration geometries, and nominally flat interfaces.