Structure Determination - Synchrotron Tomography
Synchrotron Tomography images the interior structure of real objects three-dimensionally, non-destructively, and with a high spatial resolution. This allows for a detailed microstructural analysis of many different kinds of materials or small engineering components. In the following some synchrotron tomographic images of metallic foams are pictured. All images were measured at the tomographic facility of the BAMline at the BESSY II synchrotron.
The first picture shows a powder compact (left), containing three different materials. SiC particles (cyan) with an average diameter of about 70 µm are embedded into an aluminium alloy matrix (blue). These silicon carbide particles have almost the same X-ray absorption power as the surrounding matrix.
Nevertheless, the X-ray radiation monochromatized to 25 keV allows us to separate these two phases which is hardly possible using any other kind of conventional tomography. The titanium hydride particles (red) are also easily discernible. Modern visualization tools can be used to represent the results in a convenient way. In the left part of the figure the result of the tomographic picture is displayed.
The second part shows only the titanium hydride particle whereas the rest of the matrix is transparently depictured. The third and the last part of the figure illustrates the separated SiC particles on the sample surface as well as in the material volume.
Short foamed aluminium
Due to the pressing process during the production of the material the short foamed aluminium samples mainly tear apart perpendicular to this pressing direction. The pink particles show the blowing agent TiH2.
Zinc foams (Zn + TiH2)
The two depictured zinc foams were irradiated with an energy of 60 keV. Both samples only differ in the size distribution of the attributed blowing agent particles TiH2. A blowing agent with a mean size larger than 28 µm was used for foaming in the upper figure.
In the lower figure the size distribution was lower than 28 µm. It is obvious that the pore sizes of both of the foams are correlated with the size of the blowing agents.