Pumice/aluminium syntactic foam

A novel filler material is introduced to produce high strength metal-matrix syntactic foam. Packed beds of pumice particles, a low-cost natural porous volcanic glass, with the size range of 2.8-4 mm were infiltrated with molten aluminium alloy. The resulting syntactic foams were subjected to microstructural observations and chemical analysis. Furthermore, quasi-static compression testing was applied on heat treated samples. The material strength and the deformation mechanism under compressive loading of the pumice particles and foams were investigated. The results indicate that there is a limited chemical reaction between the particles and matrix. The pumice particles considerably enhance the strength of the foam and result in an average plateau stress of 68.25 MPa and specific energy absorption of 24.8 MJ/m3. Pumice particles show higher strength in the direction of tubular pores. The mechanical anisotropy of pumice particles is likely to cause a slight variation in the directional properties of the foams.