Unexpected Planar Dislocation Boundary Formation in FCC Metals Captured by Dark-Field X-ray Microscopy and Continuum Dislocation Dynamics

TL;DR

This study combines dark-field X-ray microscopy and continuum dislocation dynamics to reveal unexpected planar dislocation boundaries in FCC metals, providing new insights into dislocation patterning and validating theoretical models with experimental data.

Contribution

First direct morphological comparison of dislocation patterning models with in situ imaging, demonstrating the predictive power of continuum dislocation dynamics for FCC metals.

Findings

Discovery of planar dislocation boundaries aligned with {111} slip planes

Synthetic contrast images from CDD match experimental observations

Validation of CDD models against in situ DFXM data

Abstract

Validating dislocation patterning models against in situ imaging experiments is a longstanding goal in materials physics. Here, we provide the first direct morphological comparison of such models. Using in situ Dark-Field X-ray Microscopy (DFXM), we map the local orientations in high-purity aluminium deformed along [100] and find unexpected planar dislocation boundaries aligned with {111} slip planes that form prior to the development of a conventional dislocation cell structure. To explain this behaviour, we generate synthetic DFXM contrast images from a continuum dislocation dynamics (CDD) simulation. This mesoscale model, using nickel as a high stacking fault energy (SFE) FCC analogue, independently predicts the formation of the same {111} planar boundary types. This correspondence demonstrates that state-of-the-art CDD and DFXM experimental data can be used synergistically - despite differences in strain rates and length scales - as a practical route for refining continuum theories of plasticity.