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Porous metals and metallic foams are presently the focus of very active research and development activities. There are currently around 150 institutions working on metallic foams worldwide, most of them focussing on their manufacture and characterisation. Various companies are developing and producing these materials which are now being used in numerous industrial applications such as lightweight structures, biomedical implants, filters, electrodes, catalysts, and heat exchangers. This review summarizes recent developments on these materials, with particular emphasis on research presented at the latest International Conference on Porous Metals and Metallic Foams (MetFoam 2007).

Articles you may be interested inAn evaluation of high energy bremsstrahlung background in point-projection x-ray radiography experimentsa) Rev. Sci. Instrum. 83, 10E528 (2012); 10.1063/1.4738649 High-energy, high-resolution x-ray imaging on the Trident short-pulse laser facilitya) Rev. Sci. Instrum. 79, 10E905 (2008); 10.1063/1.2965012Cross-sectional insight in the water evolution and transport in polymer electrolyte fuel cellsThe authors report on in situ investigations of liquid water evolution and transport in an undisturbed operating fuel cell at the microscopic level. Synchrotron x-ray radiography enhances the spatial resolution by two orders of magnitude compared to the state-of-the-art techniques in this field. The primary spots of liquid water formation, their growth, and transport inside the porous gas diffusion material were analyzed; correlations between operating conditions and the dynamics of droplet formation are described. Previous findings from modeling and simulation approaches are confirmed and the applicability for the description of in situ processes of a recently proposed model has been proven.

Structural changes in Li 2 MnO 3 cathode material for rechargeable Li-ion batteries were investigated during the 1 st and 33 rd cycles by X-ray absorption spectroscopy. It is found that both the participation of oxygen anions in redox processes and Li + -H + exchange play an important role in the electrochemistry of Li 2 MnO 3 . During activation, oxygen removal from the material along with Li gives rise to the formation of a layered MnO 2 -type structure, while the presence of protons in the interslab region, as * To whom correspondence should be addressed † Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-

Neutron imaging can provide two- or three-dimensional, spatially resolved images of the internal structure of bulk samples that are not accessible by other techniques, making it a unique tool with many potential applications. The method is now well established and is available at neutron sources worldwide. This review will give a survey of the technique of neutron imaging with a special focus on neutron tomography; the basics of the method as well as the technology of instrumentation will be outlined, and the techniques will be illustrated by representative applications. While the first part of the paper focuses on conventional attenuation contrast imaging, the second part reviews and critically assesses recent methodical developments.

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Liquid metal foam can be generated by creating gas inside a liquid or semi‐liquid metallic melt which has been pre‐treated in a suitable way. Such foams are self‐supporting disordered structures in complete analogy to aqueous foams. The stabilisation mechanism of metallic foams is still not fully understood. In order to facilitate discussion of foam stabilisation the various methods for making such foams are classified with respect to the mode of gas generation and the type of melt used for foaming. Metal foams can be produced by gas injection from an external source or by in‐situ nucleation of gas bubbles in the melt for which various possibilities are known. Melts amenable to foaming range from almost pure molten alloys to melts to which particles have been added, formed by in‐situ reactions or which have been already present in the solid precursor prior to melting. Some of the available experimental evidence for the action of stabilising particles in metallic foams is presented. It is found that although stabilisation seems to be based on the presence of a solid constituent in all the foaming processes, the mechanisms might vary. At present the nature of stabilisation is not yet fully understood and many questions remain open.