Influence of the infiltration pressure on the structure and properties of replicated aluminium foams

Replicated pure aluminium foams are produced by infiltrating identical preforms of 400 μm NaCl particles packed to 75% relative density, varying the metal infiltration pressure to vary the metal foam relative density between 15% and 25%. As the infiltration pressure is increased, small finger-like protrusions appear on the foam struts; these lower the foam permeability to fluid flow. The compressive mechanical properties of the foams, namely Young's modulus and yield stress, increase steadily with increasing relative density. Taken together, the data indicate that it is the gradual ingress of metal into narrow gaps between neighbouring particles that governs the evolution of foam properties with increasing infiltration pressure.