How to see the ‘life’ inside materials
The mechanical properties of materials are to a large extent determined by their interior 3D microstructures. Traditionally, the microstructures have been characterized by microscope techniques, such a light and electron microscopy, and these techniques only reveal the microstructures in 2D. While the microscopy techniques have given an incredible amount of very valuable microstructural information, their 2D nature has also caused misinterpretations, because it for example is not known what is under the surface. There is thus a need for microstructural characterization by non-destructive 3D experimental techniques. Requirements include high penetration power of the order of mm to cm, and high spatial resolution in the order of mm and if also crystallographic information can be obtained, it is an advantage. This calls for diffraction techniques, where only X-rays may fulfil the requirements. Starting around year 2000, there has thus been a lot of focus on the development of such X-ray techniques, first at synchrotron sources and now also at laboratory sources.
In this talk, I will present the development of a series of 3D non-destructive X-ray techniques, and illustrate their potentials by examples from the metallic materials world. This will include seeing grains growing deep in the bulk of an aluminium sample in 4D (x,y,z,time) and relations between an internal crack and the microstructure. I will also try to illustrate how 4D experimental characterization and simulations may support each other, leading to advancements in both the simulation tools and the fundamental understanding of basic phenomena like plastic deformation and annealing.