The mechanical response of ceramic microballoon reinforced aluminum matrix composites under compressive loading

Abstract An investigation is performed on the mechanical response of a family of ceramic microballoon reinforced aluminum matrix composites under both uniaxial compression and constrained die compression loadings. The key material parameters that are varied are the matrix strength and the ratio of wall thickness t to radius R of the microballoons. Uniaxial compressive failure initiates at relatively small strains (≈1–2%) and occurs through a process of crushing and collapse of the material within a localized deformation band. Under constrained die conditions, localization is suppressed and the flow stress increases monotonically with increasing strain. The latter response is well described by Gurson's constitutive law for plastic yielding of porous ductile metals, with an effective strength that depends on the relative wall thickness, t/R. Furthermore, the energy absorption capacity (≈60–70 MJ/m3) is extremely high in comparison with values that are typical of metal foams. The results suggest that the microballoon composites may be attractive for applications requiring a high resistance to penetration by projectiles or other forms of local intrusion, in combination with a high compressive strength.