Kinetic Pathways of Phase Decomposition Using Steepest-Entropy-Ascent Quantum Thermodynamics Modeling. Part II: Phase Separation and Ordering

TL;DR

This paper presents a quantum thermodynamics-based model to predict the kinetics and pathways of phase separation and ordering in alloys, capturing both equilibrium states and dynamic processes.

Contribution

It introduces a steepest-entropy-ascent equation of motion combined with a pseudo-eigenstructure to model atomic ordering and clustering kinetics.

Findings

Successfully predicts stable equilibrium states.

Captures continuous and discontinuous ordering pathways.

Models concurrent phase separation and ordering processes.

Abstract

The kinetics of ordering and concurrent ordering and clustering is analyzed with an equation of motion initially developed to account for dissipative processes in quantum systems. A simplified energy eigenstructure, or pseudo-eigenstructure, is constructed from a static concentration wave method to describe the configuration-dependent energy for atomic ordering and clustering in a binary alloy. This pseudo-eigenstructure is used in conjunction with an equation of motion that follows steepest entropy ascent to calculate the kinetic path that leads to ordering and clustering in a series of hypothetical alloys. By adjusting the thermodynamic solution parameters, it is demonstrated that the model can predict the stable equilibrium state as well as the unique thermodynamic path and kinetics of continuous/discontinuous ordering and concurrent processes of simultaneous ordering and phase separation.