Compressive Properties of Al99.5 Matrix Syntactic Foams Reinforced by SiC Particles in the Matrix

Abstract

Reinforced metal matrix syntactic foams (rMMSFs) were produced by liquid-state, low-pressure vacuum infiltration. Technical purity Al99.5 aluminum alloy was used as the matrix material, and ceramic hollow spheres (CHSs) with Ø2.24±0.13 mm diameter were applied as a filler material. The matrix was reinforced by 0.6 nominal size SiC with seven different volume fractions of the reinforcing material relative to the matrix material’s volume: 0 vol%, 5 vol%, 10 vol%, 15 vol%, 20 vol%, 25 vol%, and 30 vol%, respectively. The samples were investigated structurally and mechanically. Based on the microscopic investigation, the liquid-state, low-pressure vacuum infiltration was found to be a good production method of the rMMSFs; no traces of reactions between the components had been found. Based on the results of the standardized compressive test, the specific compressive strength and specific structural stiffness of rMMSFs were significantly increased for each reinforcement volume fraction, and even a 63.2±8.1% improvement can be achieved in the specific compressive strength compared to the unreinforced (UR) samples. The specific plateau strength and the specific energy absorption were improved with a 15 vol% or above reinforcement volume fraction compared to the UR foams. The decrement was caused by the stress-concentrating particles, and this effect could only be equalized by higher reinforcement content. The failure modes of the MMSFs were dependent on the dual composite properties of rMMSFs. The failure of the reinforced samples was indicated by plastic collapse followed by the appearance of a cleavage band and its widening.