We will initially summarise the specifications of Dark-Field X-ray Microscopy (DFXM), a diffraction-based synchrotron imaging technique analogous to dark-field TEM [1]. Thanks to an objective lens, it allows to visualise the microstructure and local strain in a slice of a mm3 sample, and this with a spatial resolution on the order of 100 nm, an angular resolution of 0.001°, and a strain resolution of 10-4 [1]. By stacking slices, 3D movies can be filmed e.g., during annealing [2]. However, due to the nature of the technique it can only image one grain and one Bragg reflection at a time. This means that it is usually coupled with coarser grain mapping methods such as 3DXRD to gain a better understanding of the surroundings of the grain of interest [3].

Here we will present work on pure aluminium (AA1090) polycrystals during in-situ tensile deformation. In particular we will present the first work (by any probe) on the subdivision of the cell structure with increasing external load (up to 10% elongation), aiming to understand cell refinement.