Emergence of near-boundary segregation zones in face-centered cubic multi-principal element alloys

TL;DR

This study uses simulations to reveal how complex multi-principal element alloys develop near-boundary segregation zones, showing that chemical complexity influences grain boundary phenomena and structural variations.

Contribution

It demonstrates the emergence of near-boundary segregation zones in multi-principal element alloys and compares these phenomena with simpler monatomic systems.

Findings

Fe enrichment near boundaries in complex alloys

Reduced atomic volume in segregated regions

Similar near-boundary effects in simpler Cu systems

Abstract

Grain boundaries have been shown to dramatically influence the behavior of relatively simple materials such as monatomic metals and binary alloys. The increased chemical complexity associated with multi-principal element alloys is hypothesized to lead to new grain boundary phenomena. To explore the relationship between grain boundary structure and chemistry in these materials, hybrid molecular dynamics/Monte Carlo simulations of a faceted {\Sigma}11 <110> tilt boundary, chosen to sample both high- and low-energy boundary configurations, are performed in face-centered cubic CrFeCoNiCu and CrFeCoNi equiatomic alloys. Unexpected enrichment of Fe is discovered in the face-centered cubic regions adjacent to the interface and found to be correlated with a structurally-distinct region of reduced atomic volume. Comparison with the boundary of the same type in monatomic Cu demonstrates that altered near-boundary regions exist in simpler systems as well, with the chemical complexity of the multi-principal element alloys highlighting its existence and importance.