Interface characterization and mechanical property of an aluminum matrix syntactic foam with multi-shelled hollow sphere structure

Abstract

The novel aluminum matrix (Al-matrix) syntactic foam with multi-shelled hollow sphere structure (HSS) was fabricated by introducing double-layered 316L-Al2O3 metal-ceramic hollow spheres (M-C HSs) through powder metallurgy method. Microstructure characterization and mechanical properties of multi-shelled HSS have been investigated by XRD, SEM, TEM/EDS and nanoindentation. Quasi-static compressive tests of Al matrix, Al-matrix syntactic foams with Al2O3 HS and M-C HS have been performed. Compressive strength (σ0.2), plateau stress (σp), plateau end strain (εpe), and energy absorption (W50) were used to analyze the effect of multi-shelled HSS in the syntactic foam. The results showed that in multiple interfaces formed in the syntactic foam, main elements diffusion was found in interface between Al2O3 and 316L shells. While, the intermetallic shell formed in interface between 316L shell and Al matrix was composed of Fe4Al13 substrate, and precipitations of Cr phases and Mo-rich phases. Therefore, a “ceramic-metal-intermetallic” multi-shelled HSS was formed in syntactic foam with M-C HS. Compressive strength of the syntactic foam was increased by 8.04% compared with that of syntactic foam with Al2O3 HS, which led to high energy absorption (W50 = 93.28 MJ/m3). Deformation mechanism of multi-shelled HSS has been discussed in this work.