Why are metal foams stable?

Although metal foams are becoming accepted engineering materials, the reason for their stability in the liquid state is still under dispute. Liquid metal foams contain solid constituents which according to the existing models stabilize foam films by either modifying the curvature of the liquid/gas (L∕G) interfaces, or by forming particle bridges across metallic films and transmitting repulsive “disjoining” forces mechanically. Using high-resolution synchrotron tomography and a quantitative three-dimensional image analysis the authors show that there is little evidence for such curvature changes or particle bridges. The authors conclude that the main stabilizing action must be due to interactions between neighboring particles attached to L∕G interfaces.