Monte Carlo study of the growth of $L1_2$ ordered domains in fcc $A_3B$ binary alloys

TL;DR

This study uses Monte Carlo simulations to analyze the late-stage growth of ordered domains in fcc A3B alloys, comparing atom-atom and vacancy-atom exchange mechanisms and their effects on domain growth anisotropy.

Contribution

It introduces a detailed comparison of two dynamic mechanisms in modeling domain growth and reveals anisotropic growth behavior with atom-atom exchange.

Findings

Anisotropic growth observed with atom-atom exchange.

Single-length scaling observed with vacancy-atom exchange.

Results align with experimental data on Cu3Au.

Abstract

A Monte Carlo study of the late time growth of $L1_2$ ordered domains on a fcc $A_3B$ binary alloy is presented. The energy of the alloy has been modeled by a nearest neighbor interaction Ising hamiltonian. The system exhibits a fourfold degenerated ground-state and two kinds of interfaces separating ordered domains: flat and curved antiphase boundaries. Two different dynamics are used in the simulations: the standard atom-atom exchange mechanism and the more realistic vacancy-atom exchange mechanism. The results obtained by both methods are compared. In particular we study the time evolution of the excess energy, the structure factor and the mean distance between walls. In the case of atom-atom exchange mechanism anisotropic growth has been found: two characteristic lengths are needed in order to describe the evolution. Contrarily, with the vacancy-atom exchange mechanism scaling with a single length holds. Results are contrasted with existing experiments in $Cu_3Au$ and theories for anisotropic growth.