Correlating grain boundary character and composition in 3-dimensions using 4D-scanning precession electron diffraction and atom probe tomography

TL;DR

This study introduces a high-resolution 3D correlation framework combining 4D-SPED and APT to analyze grain boundary structures and compositions in nanocrystalline materials, revealing segregation behaviors of Cu and Si.

Contribution

The paper presents a novel 3D correlative microscopy approach that simultaneously characterizes grain boundary structure and chemistry at the nanoscale.

Findings

Cu segregates mainly along high angle and incoherent twin boundaries.

Si segregates to low angle and incommensurate grain boundaries.

The method enables detailed 3D structure-chemistry analysis of nanomaterials.

Abstract

Grain boundaries are dominant imperfections in nanocrystalline materials that form a complex 3-dimensional (3D) network. Solute segregation to grain boundaries is strongly coupled to the grain boundary character, which governs the stability and macroscopic properties of nanostructured materials. Here, we develop a 3-dimensional transmission electron microscopy and atom probe tomography correlation framework to retrieve the grain boundary character and composition at the highest spatial resolution and chemical sensitivity by correlating four-dimensional scanning precession electron diffraction tomography (4D-SPED) and atom probe tomography (APT) on the same sample. We obtain the 3D grain boundary habit plane network and explore the preferential segregation of Cu and Si in a nanocrystalline Ni-W alloy. The correlation of structural and compositional information reveals that Cu segregates predominantly along high angle grain boundaries and incoherent twin boundaries, whereas Si segregation to low angle and incommensurate grain boundaries is observed. The novel full 3D correlative approach employed in this work opens up new possibilities to explore the 3D crystallographic and compositional nature of nanomaterials. This lays the foundation for both probing the true 3D structure-chemistry at the sub-nanometer scale and, consequentially, tailoring the macroscopic properties of advanced nanomaterials.