Effect of hollow microspheres on the thermal conductivity, flexural and compressive performance of aluminum matrix composites

This study investigates aluminum matrix composites reinforced with hollow microspheres at volume fractions ranging from 30 vol.% to 60 vol.%, fabricated via gas pressure infiltration. The effects of microspheres on microstructure, thermal conductivity, compressive and flexural properties were systematically examined. Results show that hollow microspheres are uniformly distributed within the matrix with minimal breakage and exhibit excellent interfacial bonding, characterized by the absence of voids or reaction products. As the microspheres content increases, both flexural strength and elastic modulus decrease, primarily due to microsphere fracture and interface debonding. The compressive strength, plateau stress and the energy absorption of hollow microspheres/Al composites also decrease with increasing the content of hollow microspheres. Thermal conductivity also continuously declines with increasing microspheres content. Theoretical modeling reveals that among the evaluated models – including the parallel/series models, differential effective medium (DEM), Maxwell-Garnett, and radiation-corrected DEM – the radiation-corrected DEM model provides the best agreement with experimental thermal conductivity data.