Identifying interatomic potentials for the accurate modeling of interfacial segregation and structural transitions

TL;DR

This study evaluates four interatomic potentials for the Cu-Zr system to identify which accurately model interfacial segregation and structural transitions, validated against experimental data, and extends findings to the Ni-Zr system.

Contribution

The paper systematically assesses interatomic potentials for modeling interface phenomena, highlighting the importance of enthalpy of mixing and bond energies for accurate simulations.

Findings

Potentials that match experimental segregation behavior reproduce enthalpy of mixing.

Certain potentials accurately predict nanoscale amorphous complexions.

Identified a reliable potential for Ni-Zr capable of modeling amorphous complexions.

Abstract

Chemical segregation and structural transitions at interfaces are important nanoscale phenomena, making them natural targets for atomistic modeling, yet interatomic potentials must be fit to secondary physical properties. To isolate the important factors that interatomic potentials must capture in order to accurately model such behavior, the performance of four interatomic potentials was evaluated for the Cu-Zr system, with experimental observations used to provide validation. While experimental results show strong Zr segregation to grain boundary regions and the formation of nanoscale amorphous complexions at high temperatures and/or dopant compositions, a variety of disparate behaviors can be observed in hybrid Monte Carlo/molecular dynamics simulations of doping, depending on the chosen potential. The potentials that are able to recreate the correct behavior accurately reproduce the enthalpy of mixing as well as the bond energies, providing a roadmap for the exploration of interfacial phenomena with atomistic modeling. Finally, we use our observations to find a reliable potential for the Ni-Zr system and show that this alloy should also be able to sustain amorphous complexions.