Multiscale study of the intermittency of plastic deformation by microCT and acoustic emission method in Al-2Mg alloy foam

Ubaid Ahmed1,2, Daniel Šimek1, Michal Knapek2, Tomáš Tayari2, Lukáš Horák2

1FZU, Institute of Physics of the Czech Academy of Sciences, Na Slovance 2, Prague 8,
182 21, Czech Republic

2Matfyz Charles University, Prague, Czech Republic

In this work, we investigate the multiscale characteristics of deformation intermittency in an Al–2Mg alloy foam using a combination of in situ X-ray micro-computed tomography (microCT), digital volume correlation (DVC), and acoustic emission (AE) monitoring during quasi-static loading. The global mechanical response exhibits pronounced serrations in the force–elongation curve, indicating discrete deformation events. AE measurements reveal burst-type acoustic activity occurring during these load fluctuations. Tomographic scans were acquired after each successive load drop, enabling stepwise characterization of the evolving internal structure.

Three-dimensional displacement and strain fields were computed from successive tomographic volumes using DVC. The full-field analysis reveals heterogeneous strain distributions with localized regions of elevated axial strain within the foam structure. These regions are spatially associated with structural rearrangements and local collapse of cell walls observed in the reconstructed volumes.

Comparison between DVC-derived global strain and externally measured strain highlights the influence of system compliance on the apparent macroscopic response, emphasizing the importance of internal strain measurements.

The combined microCT–DVC–AE methodology provides a framework for correlating macroscopic load fluctuations, internal strain heterogeneity, and acoustic activity, contributing to a better understanding of intermittent deformation in cellular metals.