Effects of particle size on the microstructure and mechanical properties of expanded glass-metal syntactic foams

The effect of particle size on the microstructure and mechanical properties of expanded glass-metal syntactic foams (EG-MSF) was investigated. The foams were fabricated via counter gravity infiltration of a packed bed of recycled expanded glass (EG) particles. The metallic matrix of all foam samples was A356 aluminium. Different particle sizes were considered, i.e. diameters between 1–1.4, 2–2.8 and 4–5.6 mm. The microstructures of EG-MSF were investigated by optical and scanning electron microscopy and the grain size of the aluminium alloy was found to increase with EG particle size. Uni-axial compression testing of EG-MSF indicated that its mechanical properties depend both on foam density and particle size. Smaller particles were found to dampen plateau stress oscillation and improve the energy absorption characteristics of EG-MSF.