In the field of materials science, it is common to relate mechanical or physical behaviour to microstructure in order to optimize materials. Usually the observation of the microstructure is made using an optical or electronic microscope to obtain images in two dimensions. However, the measurable parameters in 2D are limited and often the techniques involved to obtain these images are destructive. Thanks to X-ray micro-tomography it is possible to overcome these two difficulties. The purpose of this article is to show the enormous contribution of this tool in the understanding and the modelling of some physical phenomena involved in aluminium alloys.