Secondary Grain Boundary Dislocations Alter Segregation Energy Spectra

TL;DR

This study reveals that secondary grain boundary dislocations significantly influence segregation energy spectra in materials, offering new avenues for designing advanced alloys by leveraging these topologically-necessary defects.

Contribution

It demonstrates that secondary GB dislocations can have a stronger effect on segregation than defect-free boundaries, using nanoscale tomography in a Fe-W alloy.

Findings

Secondary GB dislocations alter segregation energy spectra.

Dislocations can have a stronger effect than defect-free GBs.

Potential for new material design strategies.

Abstract

Grain boundaries (GBs) trigger structure-specific chemical segregation of solute atoms. According to the three-dimensional (3D) topology of grains, GBs - although defined as planar defects - cannot be free of curvature. This implies formation of topologically-necessary arrays of secondary GB dislocations. We report here that these pattern-forming secondary GB dislocations can have an additional and, in some cases, even a much stronger effect on GB segregation than defect-free GBs. Using nanoscale correlative tomography combining crystallography and chemical analysis, we quantified the relationship between secondary GB dislocations and their segregation energy spectra for a model Fe-W alloy. This discovery unlocks new design opportunities for advanced materials, leveraging the additional degrees of freedom provided by topologically-necessary secondary GB dislocations to modulate segregation.