Interfacial microstructure and compressive properties of Al-Mg syntactic foam reinforced with glass cenospheres

Glass cenospheres/Al syntactic foams are successfully produced with about 50% volume fraction using pressure infiltration process. The interfacial reactions between glass cenospheres and Al-Mg alloys (5A03 with 3wt% Mg and 5A06 with 6wt% Mg) have been deeply studied. The MgAl2O4 crystals produced by the reaction of 2Al((l))+Mg-(l)+2SiO(2(s)) -> 2MgAl(2)O(4(s)) + 2Si((s)) are the main reaction products in the size of similar to 100 nm and the reaction layer is about 800 nm thick. The interfacial reaction region is composed of a large amount of MgAl2O4 uniformly coating on the glass cenospheres due to the spherical structure of cenosphere. Si is believed to diffuse through the grain boundaries between the MgAl2O4 crystals and aggregate on the surface of the reaction zone. With the increase of Mg content in matrix such as 5A06 alloy, Si formed above transforms into Mg2Si by the reaction of 2 Mg-(l) + Si-(s) -> Mg2Si(s). The compressive strength of composites increases With the increase of Mg content which is not only contributed to the improved strength of matrix but the suitable interfacial reaction coating and the forming of Mg2Si in matrix. (C) 2015 Elsevier B.V. All rights reserved.