Mechanical properties of particle-reinforced aluminium matrix syntactic foams

Abstract

Metal matrix syntactic foams (MMSFs) were produced by low-pressure liquid-state infiltration. AlSi7Mg alloy was used as matrix material, while the filler was a set of ceramic hollow spheres (CHSs) or light-expanded clay agglomerate particles (LECAPs). The matrix was reinforced by Al2O3 (0.6 mm or 1.2 mm nominal size) or SiC (0.4 mm nominal size) particles. The produced samples were investigated structurally (microstructure) and mechanically (standardised compressive tests). According to the microscopic investigations, liquid-state low-pressure infiltration was found to be a suitable method to produce MMSFs with a reinforced matrix. The shape of the engineering stress – strain curves was mainly influenced by the filler. CHS filled MMSFs showed a high stress peak, while LECAP filling ensured a smoother transition from the linear elastic part to the plateau region. The compressive strength of the MMSFs was significantly increased by the reinforcing particles in the matrix. Linear connections were found in the compressive strength and the nominal size of the Al2O3 particle relationships. The plateau strength of the MMSFs and thus the absorbed mechanical energy was decreased by the presence of the reinforcement. The decrement was caused by the stress-concentrating particles and could only be equalised by the stronger SiC particles. The failure modes of the MMSFs were dependent on the filler material.