In this study, Al–Cu–Mg–Ag syntactic foams containing Φ2 mm 4605 steel hollow spheres are fabricated via pressure infiltration processing. The effects of ceramic coated hollow spheres and heat treatment on the microstructure and compressive properties of the syntactic foams are investigated. The results reveal that brittle intermetallic layers and needle-like Fe-rich phases lead to brittle fracture of the syntactic foams during compression. However, the ceramic coating hollow spheres effectively suppress the formation of intermetallic layers and Fe-rich phases, resulting in a lower stress drop ratio and a more stable compressive response. T7 aging treatments significantly improve the plateau stress and energy absorption of the syntactic foams, owing to precipitation hardening in the aluminum matrix. Among all specimens, the Al–Cu–Mg–Ag syntactic foam fabricated with coated Φ2 mm 4605 hollow spheres and subjected to T7 aging exhibits the highest specific plateau stress and specific energy absorption.
Hsu et al. (Thu,) studied this question.