Analytic model for grain-boundary segregation ener-gies in metal polycrystal

TL;DR

This paper develops an analytic model that predicts grain-boundary segregation energies in metals by unifying physical effects like strain and bonding, aiding alloy design.

Contribution

It introduces a physical-based analytic framework that predicts segregation energies across various solutes and matrices in polycrystals.

Findings

Segregation energies are influenced by Coulombic-like and localized bonding effects.

The model reveals a coupling rule between solutes and matrices for segregation.

The framework aids in designing high-performance alloys.

Abstract

Solute segregation at grain boundaries (GBs) of polycrystals strongly impacts the mechanical properties of metals including strength, fracture, embrittlement, and corrosion. However, the complexity of GB structures and the large chemical space of solutes and matrices impede the understanding of segregation. Herein, we identify a physical-based determinant, by unifying the effects of plastic strain and bonding breaking, for determining the segregation energies at GBs. By further combining with the usual coordination number, atomic radius of solutes and matrices, and cohesive energy of matrices, we build an analytic framework to predict segregation energies of polycrystal GBs across various solutes and matrices. These findings indicate an unusual Coulombic-like and localized nature of the bonding at polycrystal GBs and bulk metallic glasses (BMGs). Our scheme not only uncovers the coupling rule of solutes and matrices for GB segregation in polycrystals, but also provides an effective tool for the design of high-performance alloys.