Kinetics of Joint Ordering and Decomposition in Binary Alloys

TL;DR

This study uses computer simulations to analyze the kinetics of phase segregation, ordering, and decomposition in binary alloys, revealing distinct scaling behaviors and morphology dependencies based on composition.

Contribution

It provides new insights into the dynamic processes and scaling laws governing ordering and decomposition in alloy systems through detailed simulation analysis.

Findings

Both ordering and decomposition obey scaling rules in late-stage coarsening.

Characteristic length growth follows a power law with time, modified by a constant.

Domain morphology depends on minority component concentration, indicating boundary wetting phenomena.

Abstract

We study phase segregation in a model alloy undergoing both ordering and decomposition, using computer simulations of Kawasaki exchange dynamics on a square lattice. Following a quench into the miscibility gap we observe an early stage in which ordering develops while the composition remains almost uniform. Then decomposition starts with segregation into ordered and disordered phases. The two spherically averaged structure functions, related to decomposition and to ordering, were both observed to obey scaling rules in the late coarsening stage where the time increase of the characteristic lengths was consistent with $a(t^{1/3} + b)$. While $a$ was similar for ordering and decomposition at low concentration of the minority component, it showed an increase (decrease) with concentration for ordering (decomposition). The domain morphology was found to depend on the concentration of the minority component, in a way that suggests a wetting of antiphase boundaries in the ordered domains by the disordered phase.