Characterization of aluminum alloy microstructures by means of synchrotron X-ray micro-tomography - a simple toolchain for extracting quantitative 3D morphological features

One fundamental topic in metallography is determining relations between microscopic arrangements of phases and defects, and macroscopic properties (such as tensile strength, effective stiffness tensor, effective conductivity, permeability) which are important for materials application. For multiphase materials such as aluminum-silicon alloys our work demonstrates how - in particular - three-dimensional geometric microstructure characteristics, such as particle sphericity, connectivity and contiguity can be measured accurately from 3D X-ray computed tomography scans. This study details a simple yet very effective imaging toolchain for measuring these quantities. By tailoring the three-dimensional morphology of the alloys' phases through composition, cooling and thermo-mechanical treatment one can establish a multidimensional materials database. For a given function and application, such a database would allow for optimized selection of alloy and processing, e.g. using a material which is specifically designed and produced according to its properties. The extraction of meaningful stochastic parameters from 3D CT scans of metallic alloys is therefore highly important.