arXiv subjects

Felix Frankus

Publications and source records attributed to Felix Frankus.

3 recordsLinked to original sources

arXiv2026

Revealing Dislocation Interactions Controlling Mechanical Properties of Metals

During plastic deformation, metals change shape while continuously becoming stronger. The microscopic origin of these processes lies in the proliferation and movement of line defects, dislocations, and the subsequent self-organisation and pinning of dislocations on lattice imperfections, including other dislocations. The nature of these multiscale processes has remained elusive because in situ observations have not been feasible. We present 3D movies of how dislocations pile up near an obstacle, deeply within a mm-sized pure Al sample and during tensile deformation. Cross-slip is found to provide a mechanism for the dislocations to escape the pile-up, leading to pronounced intermittent behaviour. Such data support a new generation of dislocation dynamics and micro-mechanics modelling.

cond-mat.mtrl-sci↗

arXiv2026

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

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.

cond-mat.mtrl-sci↗

arXiv2024

Observing formation and evolution of dislocation cells during plastic deformation

During plastic deformation of metals and alloys, dislocations self-organise in cells, which subsequently continuously decrease in size. How and when these processes take place has remained elusive, because observations of the structural dynamics in the bulk have not been feasible. We here present X-ray diffraction microscopy movies of the structural evolution during tensile deformation of a mm-sized aluminium (111) single crystal. The formation and subsequent development of 40,000 cells are visualised. We reveal that cells form in a stochastic and isotropic manner already at 1% strain. We show that the cell size and dislocation density distributions are log-normal and bi-modal Gaussian distributions, respectively, throughout. This insight leads to an interpretation of the formation and evolution steps in terms of universal stochastic multiplicative processes. This work will guide dislocation dynamics modelling, as it provides unique results on cell formation.

cond-mat.mtrl-sci↗