Microstructure Aspects of 7075 Al-SiO₂ Composite Foams Produced by Direct Melt Foaming Method

Abstract:

Direct melt foaming method was used to fabricate 7075 Al-SiO₂ composite foams from recycled beverage aluminum cans and SiO₂ waste particles. The microstructures of the produced composite foams revealed typical characteristic features of the conventional foams, where large dark areas (pores), curved cell walls, cell edges, nodes on the cell edges, cell walls and plateau regions were observed. The microstructures of the composite foams showed fine and irregular shape of SiO₂ particles, which were uniformly distributed in the cell wall and plateau region of composite foams. The grain size of α-Al was reduced by the addition of SiO₂, indicating that the refining effect of the SiO₂ is due to heterogeneous nucleation of the α-Al grain by SiO₂ particles or restriction of the α-Al grain growth by the SiO₂ particles, or both. SEM and EDX indicated that the SiO₂ particles reacted with the molten 7075 Al during melting and foaming process, forming MgAl₂O₄, MgO, Al₂O₃ and Mg₂Si.

• Periodical: Key Engineering Materials (Volume 835)
• Pages: 7-12
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.835.7
• Online since: March 2020
• Authors: Atef Daoud*, M.T. Abou El-Khair, Fatma Firouz, Ahmed Lotfy, Essam Ahmed
• Keywords: 7075 Al Alloy, Aluminum Cans, Composite Foams, Microstructures, Silica Particles

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