An investigation on the effect of heat treatment on the compression behavior of aluminum matrix syntactic foam fabricated by sandwich infiltration casting

In this research, syntactic foams including Al-7075 matrix and 2-4 mm low-cost pumice particles were manufactured via a novel casting method called as sandwich infiltration. According to physical evaluations, thanks to extremely porous structure of pumice, density values of the fabricated foams varied between 1.42 and 1.61 g/cm³. Porosity values were between 40.62% and 47.39%. Microstructural observations showed that there was a perfect infiltration between Al matrix and pumice particles because of correct process optimization (process pressure of 0.1 MPa, matrix melting temperature of 720°C and filler pre-temperature of 500°C). Furthermore, T6 treatment was applied to samples to comprehend effect of the aging on mechanical properties. The results indicated that there was an affirmative relation between the heat treatment and quasi-static compressive properties of the fabricated foams. The highest compressive strength, plateau stress and energy absorption values were measured as 64.4 MPa, 74.3 MPa and 34 MJ/m³ for heat treated samples. It was also observed that although the highest energy efficiency of 0.89 was calculated for heat treated sample, there was no relation between the heat treatment and efficiency. As for failure modes, as-cast samples exhibited ductile barreling characteristic whereas T6 treated foams indicated brittle v-shape fracture.