In-Situ Visualization of Long-Range Defect Interactions at the Edge of Melting

TL;DR

This paper uses advanced X-ray microscopy to directly observe how dislocations in bulk aluminum move and interact near melting, revealing their role in destabilizing the structure at high temperatures and aiding multiscale modeling.

Contribution

It introduces time-resolved dark-field X-ray microscopy for in-situ visualization of dislocation dynamics deep inside bulk materials.

Findings

Dislocations move and interact over hundreds of micrometers.

Weakened binding forces destabilize the structure at 99% melting temperature.

Real-time movies reveal thermally-activated dislocation behavior.

Abstract

Connecting a bulk material's microscopic defects to its macroscopic properties is an age-old problem in materials science. Long-range interactions between dislocations (line defects) are known to play a key role in how materials deform or melt, but we lack the tools to connect these dynamics to the macroscopic properties. We introduce time-resolved dark-field X-ray microscopy to directly visualize how dislocations move and interact over hundreds of micrometers, deep inside bulk aluminum. With real-time movies, we reveal the thermally-activated motion and interactions of dislocations that comprise a boundary, and show how weakened binding forces inhomogeneously destabilize the structure at 99% of the melting temperature. Connecting dynamics of the microstructure to its stability, we provide important opportunities to guide and validate multiscale models that are yet untested.