foam metal[¦fōm ′med·əl]
a metal or alloy with a cellular internal structure in which gas is contained in thin-walled metal pockets.
Foam metals are produced by introducing hydrides of various elements, for example, titanium and zirconium, into the molten metal. The hydrogen that is released during the decomposition of the hydride foams the metal, and the resultant cellular structure is fixed by rapid cooling. The properties of foam metals depend on the amount of absorbed gas and on the properties of the starting metal or alloy. Aluminum and magnesium are among the metals that are foamed.
Foam metals are used in thermal insulation and as fillers to impart rigidity to structures.