Metallographic Tomography

For the elucidation of the process-structure-property relationships of materials, 3D information about the microstructure is required. For this purpose, the classical metallographic microsection must be extended in such a way that a stack of superimposed planes is prepared and tomographically assembled to form a micrograph of a volume region.

This task is performed robot-assisted at Fraunhofer IWS. With the RoboMet 3D, the entire metallographic sequence of grinding, polishing, etching and microscopy steps can be automated and repeated many times without the need for operator intervention. The sizes of the examined volumes are typically in the range of cubic centimeters. The distances between the ground sections are freely selectable and the microscopic resolution extends to the limit achievable by light microscopy in the submicrometer range.

The possibilities of structure elucidation with this method go significantly beyond the usual information and resolutions achievable with computed tomography. On this basis, the material structures in metals and other materials can be evaluated and influenced, e.g. for joining technologies, additive manufacturing processes or coatings.

The automated production of metallographic sections enables effective layer-by-layer ablation, preparation and microscopy of material volumes. The layer stack of microscopic images generated in this process – typically in at least 100 planes – enables tomographic imaging with much higher resolution than with X-ray CT. All microstructural details can be imaged that are also representable in classical 2D metallography.