Atomistic modeling of interfacial segregation and structural transitions in ternary alloys

TL;DR

This study uses hybrid simulations to explore how dopants segregate and induce structural changes at grain boundaries in ternary alloys, revealing synergistic effects and conditions for amorphous film formation.

Contribution

It extends grain boundary segregation analysis from binary to ternary alloys, uncovering new behaviors and mechanisms in dopant interactions and structural transitions.

Findings

Different solutes prefer distinct segregation sites in Al-Zr-Cu.

Site competition occurs in Cu-Zr-Ag, affecting segregation.

Ternary systems can form thicker amorphous intergranular films by adjusting solute ratios.

Abstract

Grain boundary engineering via dopant segregation can dramatically change the properties of a material. For metallic systems, most current studies concerning interfacial segregation and subsequent transitions of grain boundary structure are limited to binary alloys, yet many important alloy systems contain more than one type of dopant. In this work, hybrid Monte Carlo/molecular dynamics simulations are performed to investigate the behavior of dopants at interfaces in two model ternary alloy systems: Cu-Zr-Ag and Al-Zr-Cu. Trends in boundary segregation are studied, as well as the propensity for the grain boundary structure to become disordered at high temperature and doping concentration. For Al-Zr-Cu, we find that the two solutes prefer to occupy different sites at the grain boundary, leading to a synergistic doping effect. Alternatively, for Cu-Zr-Ag, there is site competition because the preferred segregation sites are the same. Finally, we find that thicker amorphous intergranular films can be formed in ternary systems by controlling the concentration ratio of different solute elements.