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Interfacial behavior and impact on the mechanical properties of Mg matrix syntactic foams manufactured by infiltration castingThursday (08.10.2020) 16:30 - 16:50
Metal matrix syntactic foams are representing a relatively novel class of closed-cell metal-ceramic composite foams. They consist of ceramic hollow spheres embedded into a metal matrix for example Al, Mg and steel. In the area of structural materials, the Mg-based metal matrix syntactic foams provide a high potential due to the combination of brittle ceramic hollow spheres with a ductile and low-density Mg matrix. This leads to a higher specific strength compared to other metallic matrices used in syntactic foams. The possibility to change the interface between different ceramics and Mg enables a new way to influence the foams microstructure, resulting in a change of the mechanical properties. Since past studies have only investigated simple combinations of Mg-based matrices and ceramic hollow spheres, there is still a huge research potential to study the impact of different interface formations on the compressive behavior of Mg-based syntactic foams. This work addresses exactly this aspect and investigates the influence of the interface formation on the mechanical properties of these syntactic foams by using different ceramic materials and changing of the production parameters. The syntactic foams are manufactured using pure Mg in combination with alumina and alumina-silica spheres to evaluate the influence of Si on the interface formation within a low-pressure infiltration casting method. Variation of casting parameters as well as the cooling conditions lead to different interfacial behaviors. The resulting change of the interface, microstructure and mechanical behavior are being investigated. The microstructural characterization is being done using light and scanning electron microscopy as well as nanoindentation. The as-gained results from the microstructural characterization are compared with the results of the mechanical testing in order to gain a holistic understanding of the influence of the Mg-Al2O3/SiO2 interface on the mechanical properties of the syntactic foams.