Cellular metallic material
"Metal foam" or "metallic foam" has become a very popular term which is nowadays used for almost any kind of metallic material which contains voids. It might be useful to distinguish various expressions:
These definitions are not mutually exclusive. A foam, e.g., is also a porous and a cellular structure, but a sponge does not necessarily have to contain cells. Moreover, as real materials are imperfect the distinction is sometimes not easy. What, e.g., is a foam with perforated cell walls? Still "cellular" or already a sponge? Looking at the examples shown one can try to classify:
The first picture shows an aluminium foam, the second is a cellular iron-based material with cells extending in one dimension (MER Corp.), the third represents ordinary sintered bronze powders which actually form a metal sponge (instead, however, such structures are rather called "sinter metal" or even "porous metal"), the fourth shows an aluminium sponge, which could also be called cellular if one relaxes the condition that the cells be closed. The fifth shows a nickel sponge (Inco).
As all these materials are interesting from a technological viewpoint the web page metalfoam.net will not be restricted to true "metal foams" but also consider all other types mentioned in this short introduction.