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The effective thermal conductivity of open-pore metal foams in combination with the fluids air and water have been investigated in an extended range in relative density and selection of material. This study is conducted to estimate the influence of the thermal conductivities of the combination “metal foam — fluid” λs and λfl on the effective thermal conductivity λe of the open-pore metal foam. Therefore, open-pore metal foams (ρrel = 12.7 % in average) of different base materials are manufactured by respect of significant differences in the thermal conductivity of their bulk material in a range of 24.80 W × (m × K)−1≤λs≤ 402.13 W × (m × K)−1. These samples are saturated by air and water and the effective thermal conductivities of the corresponding combinations are determined. The thereto used method is a transient one and is based on the theory of inturbide temperature fields. The impact of the fluid type on λe is evaluated and its dependence on λs is identified, resulting in a simple expression for estimating the effective thermal conductivity as a function of λfl, λs and ρrel applicable for air and water.

This work presents open-pore metal foams made by investment casting from several pure metals. The resulting microstructure and its morphology will be characterized and compared to the microstructure of permanent mold cast round specimens. In addition to their manufacture, the preparation of the different samples for microstructural characterization is outlined. Finally, the individual microstructures are analyzed and compared by means of light microscopy and under consideration of relevant parameters. The comparison of metal foam and round specimen microstructures yields significant differences in the microstructural development.

Open-porous metal foams are cellular structures that can be defined, in simplified terms, as interwoven networks of metal ligaments that are surrounded by a fluid (liquid or gaseous). They are characterized by a very low relative density of usually 4 to 12% of the density of a solid composed of an identical base material. As such they have a small volume along with a very large surface area, providing for numerous interesting physical properties with resulting practical applications. A detailed description of the physical properties of these materials essentially requires a characterization of their geometric structure. Within the scope of this work, microsections of these foam structures are captured in a defined depth distance of sz ≤0,5 mm. In the course of the experiment, these microsections are software-converted to binary images. They are optimized in a way that artifact characteristics, which would have a negative effect on the analysis, converge to a minimum. Based hereon, it is now possible to generate realistic 3D models of individual microsections, allowing for a three-dimensional measurement of the material. Furthermore, binary format microsections allow for determining miscellaneous statistical characteristic values of the examined foam structures. Based on these results, it is consequently very easy to draw conclusions on the geometry of large-dimensional foam structures. When varying individual characteristic parameters, such a database also provides the possibility to generate differing geometric structures, which, in turn, provide for a sound basis in order to create scalable simulation models.

Efficient simulation techniques are conceived, amongst other things, for the modelling and visualization of microstructure configurations of materials and structural components in production processes, within a joint research project in which the Karlsruhe, Aalen, and Pforzheim Universities were involved. To this end, it is firstly necessary to determine the structure in all of the three spatial directions (three dimensions) which then will help to establish mathematical simulation algorithms. In the further course of the project, it is also understood that the simulation results are checked up and verified again and again by the respective real structures. These activities indispensably presuppose a precise localization of the structure on several planes and a definition as to what is realized via so-called in-depth microsections. This makes it necessary to develop and optimize techniques both for the exact maintenance of an x-y local constancy and absolutely accurate depth determination (z coordinate). For this purpose, the Pforzheim University formulated a simple metallographic process technology which is aimed at precisely localizing the structures at a well-defined material removal rate. It is on this basis that structural regions can now be detected on several planes at the same location and a sufficient collection of data can be created for the three-dimensional simulations of polycrystalline grain structures.

Low alloy copper-based alloys are mainly used as conductive material in the field of electrical engineering. However, given a good electrical conductivity, they are characterized by low mechanical strength. Due to a low alloy content of currently used copper-magnesium, alloys rank among not precipitable homogeneous solid solutions. As a consequence, increases in strength can only be realized by means of solid solution strengthening and strain hardening. Up to now, the possibility of precipitation hardening remains largely untapped. In order to examine this potential for optimization regarding higher strength and enhanced conductivity, samples with differing Mg contents are prepared and systematically heat treated. This research work has the long-term objective of leaving the laboratory scale in order to make precipitable copper-magnesium alloys applicable for industry.