Composition Patterning in Systems Driven by Competing Dynamics

TL;DR

This paper investigates how competing thermally-driven diffusion and externally imposed atomic exchanges influence pattern formation in alloys, revealing conditions for stabilizing labyrinthine structures and potential applications in nanoscale material engineering.

Contribution

It introduces a Cahn-Hilliard-type model demonstrating how finite-range, athermal exchanges can stabilize complex patterns in alloys under irradiation.

Findings

Labyrinthine patterns form when exchange range exceeds a critical value.

Steady-state patterns depend on the frequency of external exchanges.

Ion beams can be used to control nanoscale features in materials.

Abstract

We study an alloy system where short-ranged, thermally-driven diffusion competes with externally imposed, finite-ranged, athermal atomic exchanges, as is the case in alloys under irradiation. Using a Cahn-Hilliard-type approach, we show that when the range of these exchanges exceeds a critical value, labyrinthine concentration patterns at a mesoscopic scale can be stabilized. Furthermore, these steady-state patterns appear only for a window of the frequency of forced exchanges. Our results suggest that ion beams may provide a novel route to stabilize and tune the size of nanoscale structural features in materials.